ORCID Profile
0000-0002-4289-444X
Current Organisation
University of Adelaide
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Genetic Development (Incl. Sex Determination) | Cell Development (Incl. Cell Division And Apoptosis) | Neurogenetics | Biochemistry and Cell Biology | Gene Expression | Physiology | Physiology Not Elsewhere Classified | Genetics | Cell Neurochemistry | Animal Physiology—Systems |
ANZSRC Socio-Economic Objective (SEO)
Nervous system and disorders | Behavioural and cognitive sciences | Clinical health not specific to particular organs, diseases and conditions | Blood disorders | Skin and related disorders | Livestock not elsewhere classified | Endocrine organs and diseases (incl. diabetes) | Biological sciences
Related Links
Publications
Alzheimer disease: Amyloidogenesis, the presenilins and animal models
Publisher: Elsevier BV
Date: 03-2007
DOI: 10.1016/J.BBADIS.2006.12.001
Abstract: Alzheimer's disease is the most prevalent form of dementia. Neuropathogenesis is proposed to be a result of the accumulation of amyloid beta peptides in the brain together with oxidative stress mechanisms and neuroinflammation. The presenilin proteins are central to the gamma-secretase cleavage of the amyloid prescursor protein (APP), releasing the amyloid beta peptide. Point mutations in the presenilin genes lead to cases of familial Alzheimer's disease by increasing APP cleavage resulting in excess amyloid beta formation. This review discusses the molecular mechanism of Alzheimer's disease with a focus on the presenilin genes. Alternative splicing of transcripts from these genes and how these may function in several disease states is discussed. There is an emphasis on the importance of animal models in elucidating the molecular mechanisms behind the development of Alzheimer's disease and how the zebrafish, Danio rerio, can be used as a model organism for analysis of presenilin function and Alzheimer's disease pathogenesis.
Contribution of mGluR and Fmr1 functional pathways to neurite morphogenesis, craniofacial development and fragile X syndrome
Publisher: Oxford University Press (OUP)
Date: 25-10-2006
DOI: 10.1093/HMG/DDL422
Abstract: Fragile X Syndrome is a leading heritable cause of mental retardation that results from the loss of FMR1 gene function. Studies in mouse and Drosophila model organisms have been critical in understanding many aspects of the loss of function of the FMR1 gene in the human syndrome. Here, we establish that the zebrafish is a useful model organism for the study of the human fragile X syndrome and can be used to examine phenotypes that are difficult or inaccessible to observation in other model organisms. Using morpholino knockdown of the fmr1 gene, we observed abnormal axonal branching of Rohon-Beard and trigeminal ganglion neurons and guidance and defasciculation defects in the lateral longitudinal fasciculus. We demonstrate that this axonal branching defect can be rescued by treatment with MPEP [2-methyl-6-(phenylethynyl) pyridine]. This is consistent with an interaction between mGluR signalling and fmr1 function in neurite morphogenesis. We also describe novel findings of abnormalities in the abundance of trigeminal ganglion neurons and of craniofacial abnormalities apparently due to dysmorphic cartilage formation. These abnormalities may be related to a role for fmr1 in neural crest cell specification and possibly in migration.
A familial Alzheimer's disease-like mutation in the zebrafish presenilin 1 gene affects brain energy production
Publisher: Cold Spring Harbor Laboratory
Date: 06-02-2019
DOI: 10.1101/542134
Abstract: To prevent or ameliorate Alzheimer's disease (AD) we must understand its molecular basis. AD develops over decades but detailed molecular analysis of AD brains is limited to postmortem tissue where the stresses initiating the disease may be obscured by compensatory responses and neurodegenerative processes. Rare, dominant mutations in a small number of genes, but particularly the gene PRESENILIN 1 ( PSEN1 ), drive early onset of familial AD (EOfAD). Numerous transgenic models of AD have been constructed in mouse and other organisms, but transcriptomic analysis of these models has raised serious doubts regarding their representation of the disease state. Since we lack clarity regarding the molecular mechanism(s) underlying AD, we posit that the most valid approach is to model the human EOfAD genetic state as closely as possible. Therefore, we sought to analyse brains from zebrafish heterozygous for a single, EOfAD-like mutation in their PSEN1 -orthologous gene, psen1 . We previously introduced an EOfAD-like mutation (Q96_K97del) into the endogenous psen1 gene of zebrafish. Here, we analysed transcriptomes of young adult (6-month-old) entire brains from a family of heterozygous mutant and wild type sibling fish. Gene ontology (GO) analysis revealed effects on mitochondria, particularly ATP synthesis, and on ATP-dependent processes including vacuolar acidification.
Accelerated brain aging towards transcriptional inversion in a zebrafish model of familial Alzheimer’s disease
Publisher: Cold Spring Harbor Laboratory
Date: 09-02-2018
DOI: 10.1101/262162
Abstract: Alzheimer’s disease (AD) develops silently over decades. We cannot easily access and analyse pre-symptomatic brains, so the earliest molecular changes that initiate AD remain unclear. Previously, we demonstrated that the genes mutated in early-onset, dominantly-inherited familial forms of AD (fAD) are evolving particularly rapidly in mice and rats. Fortunately, some non-mammalian vertebrates such as the zebrafish preserve fAD-relevant transcript isoforms of the PRESENILIN ( PSEN1 and PSEN2 ) genes that these rodents have lost. Zebrafish are powerful vertebrate genetic models for many human diseases, but no genetic model of fAD in zebrafish currently exists. We edited the zebrafish genome to model the unique, protein-truncating fAD mutation of human PSEN2 , K115fs. Analysing the brain transcriptome and proteome of young (6-month-old) and aged, infertile (24-month-old) wild type and heterozygous fAD-like mutant female sibling zebrafish supports accelerated brain aging and increased glucocorticoid signalling in young fAD-like fish, leading to a transcriptional ‘inversion’ into glucocorticoid resistance and vast changes in biological pathways in aged, infertile fAD-like fish. Notably, one of these changes involving microglia-associated immune responses regulated by the ETS transcription factor family is preserved between our zebrafish fAD model and human early-onset AD. Importantly, these changes occur before obvious histopathology and likely in the absence of Aβ. Our results support the contributions of early metabolic and oxidative stresses to immune and stress responses favouring AD pathogenesis and highlight the value of our fAD-like zebrafish genetic model for elucidating early changes in the brain that promote AD pathogenesis. The success of our approach has important implications for future modelling of AD.
Distinct and regulated expression of Notch receptors in hematopoietic lineages and during myeloid differentiation
Publisher: Wiley
Date: 11-2001
DOI: 10.1002/1521-4141(200111)31:11<3240::AID-IMMU3240>3.0.CO;2-E
Abstract: Hematopoietic development is a delicate balance of cell fate decisions in multipotent cells between self-renewal and differentiation. In multiple developmental systems, the Notch receptors are important factors regulating these processes. Hematopoietic progenitor cells have been shown to express Notch1, and studies with an activated intracellular form has revealed a functional role. To assess the function of other Notch members in hematopoiesis, we investigated the expression pattern of Notch1, Notch2, and Notch3 in hematopoietic lineages at the level of RNA and protein. We demonstrate that Notch1 and Notch2 are expressed in multiple lineages, and that Notch1 in particular appears to be regulated during myeloid differentiation. Notch1 was up-regulated and expressed at high levels in adherent macrophages. Mast cells expressed only low levels of Notch1 mRNA whereas Notch2 mRNA was highly expressed. In addition we could detect Notch3 mRNA and protein in cell lines representing mast cell progenitors. These expression patterns imply that the different Notch genes may have very distinct functions during hematopoiesis, and that Notch3 could be a specific regulator of mast cell development. The finding that Notch1 was up-regulated in the adherent cells developing from a multipotent progenitor cell line suggests that this protein may posses dual functions in hematopoiesis, i.e. at the stage of cell fate decision, and at the maturation stage of monocytes when adhesion to the specific microenvironment is accomplished.
Generation and PCR Screening of Bacteriophage λ Sublibraries Enriched for Rare Clones the Sublibrary Method)
Publisher: Humana Press
Date: 2002
Complementary and combinatorial patterns of Notch gene family expression during early mouse development
Publisher: Elsevier BV
Date: 11-1995
DOI: 10.1016/0925-4773(95)00451-3
Abstract: The Drosophila Notch gene encodes a transmembrane receptor involved in the regulation of cell fate. It exerts its effect by lateral specification, inductive signaling and is also important for cell adhesion and axonal pathfinding. In this report we analyse the expression of the three mammalian Notch homologues during early mouse development by in situ hybridization. The Notch 1, 2 and 3 genes show dynamic and complex expression patterns, in particular during gastrulation and somitogenesis and in early nervous system formation. During gastrulation, the Notch genes are expressed in non-overlapping, successive patterns. Notch 3 is widely expressed in both ectoderm and mesoderm. Notch 2 is then expressed in the node, notochord and neural groove while Notch 1 becomes highly expressed in presomitic mesoderm. As somitogenesis begins, Notch 2 expression is activated in newly forming somites while Notch 3 is activated in mature somites. Various neural crest cell populations and ectodermal placode cells can be defined by expression of specific combinations of Notch genes. All three Notch genes are expressed within cells of the dorsal neural tube at E9.5, although neural crest cells that have begun migrating all show distinct patterns of Notch expression. Finally, Notch 1 expression is observed not only in placodes, but also in cells migrating from placodes to the site of the ganglia anlagen. This expression pattern may be analogous to Notch expression in the peripheral nervous system of Drosophila, suggesting that mammalian Notch genes may also be involved in axonal pathfinding.
Aicardi Syndrome Is a Genetically Heterogeneous Disorder
Publisher: MDPI AG
Date: 31-07-2023
Abstract: Aicardi Syndrome (AIC) is a rare neurodevelopmental disorder recognized by the classical triad of agenesis of the corpus callosum, chorioretinal lacunae and infantile epileptic spasms syndrome. The diagnostic criteria of AIC were revised in 2005 to include additional phenotypes that are frequently observed in this patient group. AIC has been traditionally considered as X-linked and male lethal because it almost exclusively affects females. Despite numerous genetic and genomic investigations on AIC, a unifying X-linked cause has not been identified. Here, we performed exome and genome sequencing of 10 females with AIC or suspected AIC based on current criteria. We identified a unique de novo variant, each in different genes: KMT2B, SLF1, SMARCB1, SZT2 and WNT8B, in five of these females. Notably, genomic analyses of coding and non-coding single nucleotide variants, short tandem repeats and structural variation highlighted a distinct lack of X-linked candidate genes. We assessed the likely pathogenicity of our candidate autosomal variants using the TOPflash assay for WNT8B and morpholino knockdown in zebrafish (Danio rerio) embryos for other candidates. We show expression of Wnt8b and Slf1 are restricted to clinically relevant cortical tissues during mouse development. Our findings suggest that AIC is genetically heterogeneous with implicated genes converging on molecular pathways central to cortical development.
A Rapid Apoptosis Assay Measuring Relative Acridine Orange Fluorescence in Zebrafish Embryos
Publisher: Mary Ann Liebert Inc
Date: 08-2007
Abstract: The ability to easily analyze apoptosis is important in studies of molecular cell biology and to evaluate the relative toxicity of different treatments or environments. This is particularly the case when substances such as morpholino oligonucleotides are injected into embryos, as such treatments can cause widespread, complex patterns of apoptosis. Zebrafish embryos are well suited for cell biological and environmental toxicity analyses, but the need remains for a simple method that can analyze levels of apoptosis in a statistically significant number of embryos. Here we present a "group fluorescence" method for rapid, large-scale analysis of relative levels of apoptosis based on densitometric techniques.
Transcriptome analysis indicates dominant effects on ribosome and mitochondrial function of a premature termination codon mutation in the zebrafish gene psen2
Publisher: Cold Spring Harbor Laboratory
Date: 20-04-2020
DOI: 10.1101/2020.04.20.050815
Abstract: PRESENILIN 2 ( PSEN2 ) is one of the genes mutated in early onset familial Alzheimer’s disease (EOfAD). PSEN2 shares significant amino acid sequence identity with another EOfAD-related gene PRESENILIN 1 ( PSEN1 ), and partial functional redundancy is seen between these two genes. However, the complete range of functions of PSEN1 and PSEN2 is not yet understood. In this study, we performed targeted mutagenesis of the zebrafish psen2 gene to generate a premature termination codon close downstream of the translation start with the intention of creating a null mutation. Homozygotes for this mutation, psen2 S4Ter , are viable and fertile, and adults do not show any gross pigmentation defects, arguing against significant loss of γ-secretase activity. Also, assessment of the numbers of Dorsal Longitudinal Ascending (DoLA) interneurons that are responsive to psen2 but not psen1 activity during embryogenesis did not reveal decreased psen2 function. Transcripts containing the S4Ter mutation show no evidence of destabilization by nonsense-mediated decay. Forced expression in zebrafish embryos of fusions of psen2 S4Ter 5’ mRNA sequences with sequence encoding enhanced green fluorescent protein (EGFP) indicated that the psen2 S4Ter mutation permits utilization of cryptic, novel downstream translation start codons. These likely initiate translation of N-terminally truncated Psen2 proteins that obey the “reading frame preservation rule” of PRESENILIN EOfAD mutations. Transcriptome analysis of entire brains from a 6-month-old family of wild type, heterozygous and homozygous psen2 S4Ter female siblings revealed profoundly dominant effects on gene expression likely indicating changes in ribosomal, mitochondrial, and anion transport functions.
Independent and cooperative action of Psen2 with Psen1 in zebrafish embryos
Publisher: Elsevier BV
Date: 10-2009
DOI: 10.1016/J.YEXCR.2009.06.023
Abstract: Presenilin1 (PSEN1) and presenilin2 (PSEN2) are involved in the processing of type-1 transmembrane proteins including the amyloid precursor protein (APP), Notch and several others. PSEN1 has been shown to be crucial for proteolytic cleavage of Notch in developing animal embryos. Mouse embryos lacking Psen1 function show disturbed neurogenesis and somite formation, resembling Notch pathway mutants. However, loss of Psen2 activity reveals only a minor phenotype. Zebrafish embryos are a valuable tool for analysis of the molecular genetic control of cell differentiation since endogenous gene expression can be modulated in subtle and complex ways to give a phenotypic readout. Using injection of morpholino antisense oligonucleotides to inhibit protein translation in zebrafish embryos, we show that reduced Psen2 activity decreases the number of melanocytes in the trunk but not in the cranial area at 2 days post fertilisation (dpf). Reduced Psen2 activity apparently reduces Notch signalling resulting in perturbed spinal neurogenin1 (neurog1) expression, neurogenesis and trunk and tail neural crest development. Similar effects are seen for reduced Psen1 activity. These results suggest that Psen2 plays a more prominent role in Notch signalling and embryo development in zebrafish than in mammals. Intriguingly, decreased Psen2 activity increases the number of Dorsal Longitudinal Ascending (DoLA) interneurons in the spinal cord while decreased Psen1 activity has no effect. However, the effect on DoLAs of reduced Psen2 can be ameliorated by Psen1 loss. The effects of changes in Psen2 activity on DoLA interneurons and other cells in zebrafish embryos provide bioassays for more detailed dissection of Psen2 function.
The Peak of the Oil Age – Analyzing the world oil production Reference Scenario in World Energy Outlook 2008
Publisher: Elsevier BV
Date: 03-2010
Transcriptome analysis indicates dominant effects on ribosome and mitochondrial function of a premature termination codon mutation in the zebrafish gene psen2
Publisher: Public Library of Science (PLoS)
Date: 13-07-2020
The Human NOTCH1, 2, and 3 Genes Are Located at Chromosome Positions 9q34, 1p13-p11, and 19p13.2-p13.1 in Regions of Neoplasia-Associated Translocation
Publisher: Elsevier BV
Date: 11-1994
Abstract: In Drosophila the Notch gene controls differentiation to various cell fates in many tissues. Three mammalian Notch homologs have recently been identified: Notch 1, 2, and 3. All three homologs are very highly conserved relative to the Drosophila Notch gene, which suggests that they are important for cell differentiation in mammals. This notion is supported by the previous finding of a truncated, translocated form of the human NOTCH1 gene (formerly TAN1) in three cases of leukemia. Given this genetic link between NOTCH1 and tumor formation, it is of interest to establish the chromosomal positions of the other two homologs. We report the identification of cosmid clones for the human NOTCH1, 2, and 3 genes. These clones were used as probes in fluorescence in situ hybridization to human metaphase chromosomes, and the results, combined with data from somatic cell hybrid panels, show that the NOTCH2 and 3 genes are located at positions 1p13-p11 and 19p13.2-p13.1, respectively, which are regions of neoplasia-associated translocation.
Zebrafish models of Mucopolysaccharidosis types IIIA, B, & C show hyperactivity and changes in oligodendrocyte state
Publisher: Cold Spring Harbor Laboratory
Date: 03-08-2023
DOI: 10.1101/2023.08.02.550904
Abstract: Sanfilippo syndrome childhood dementia, also known as mucopolysaccharidosis type III (MPS III), is a rare inherited lysosomal storage disorder. Subtypes of MPS III are caused by deficiencies in one of four enzymes required for degradation of the glycosaminoglycan heparan sulfate (HS). An inability to degrade HS leads to progressive neurodegeneration and death in the second or third decades of life. Knowledge of MPS III pathogenesis is incomplete, and no effective therapies exist. We generated the hypomorphic mutations sgsh S387Lfs , naglu A603Efs and hgsnat G577Sfs in the endogenous zebrafish genes orthologous to human SGSH , NAGLU , and HGSNAT that are loci for mutations causing MPS III subtypes MPS IIIA, B and C respectively. Our models display the primary MPS III disease signature of significant brain accumulation of HS, while behavioural analyses support hyperactivity phenotypes. Brain transcriptome analysis revealed changes related to lysosomal, glycosaminoglycan, immune system and iron homeostasis biology in all three models but also distinct differences in brain transcriptome state between models. The transcriptome analysis also indicated marked disturbance of the oligodendrocyte cell state in the brains of MPS IIIA, B and C zebrafish, supporting that effects on this cell type are an early and consistent characteristic of MPS III. Overall, our zebrafish models recapture key characteristics of the human disease and phenotypes seen in mouse models. Our models will allow exploitation of the zebrafish’s extreme fecundity and accessible anatomy to dissect the pathological mechanisms both common and ergent between the MPS IIIA, B, and C subtypes.
Sequence of zebrafish fibulin-1 and its expression in developing heart and other embryonic organs
Publisher: Springer Science and Business Media LLC
Date: 04-11-1997
Abstract: Using a homology-based cDNA cloning strategy we have identified a member of the fibulin family in the zebrafish Danio rerio. The deduced sequence of this protein is highly homologous to mammalian fibulins. Two variants of this protein have been identified and they were found to correspond to variants C and D of mammalian fibulin-1. RT-PCR showed that variant C is expressed as early as the blastula period, whereas variant D was first detected during gastrulation. By in situ hybridization with a probe detecting both variants, fibulin-1 could first be detected during the late gastrula period. During the segmentation period, fibulin-1 transcripts are restricted to the most posterior presomitic mesoderm and to cells lying at the lateral boundary of the embryo proper and the yolk. Subsequently, whilst the tail is budding and elongating, fibulin-1 transcripts are localized in the most posterior part of the extending tail tip and in the region of somite formation. At the early hatching period, highly restricted expression of fibulin-1 mRNA is observed in the heart at the region where the valves are forming. Fibulin-1 mRNA is also present in the mesenchymal cells underlying the apical ectodermal ridge in the pectoral fins and in the inner three quarters of the tail fin. In addition, high levels of fibulin-1 expression are seen in the developing swim bladder, which by rapid contraction and expansion regulates swimming altitude. It is thus notable that fibulin-1 is prominently expressed in regions where tissue compartments are continuously moving in relation to each other. These and previous observations of expression of fibulins in heart valves in mouse and chicken suggest that fibulins evolved as specialized extracellular matrix components for tissues involved in continuous stretching both during embryogenesis and at later stages.
Brain transcriptome analysis of a familial Alzheimer's disease-like mutation in the zebrafish presenilin 1 gene implies effects on energy production
Publisher: Springer Science and Business Media LLC
Date: 03-05-2019
Models of Alzheimer’s Disease
Publisher: Elsevier
Date: 2013
A Zebrafish Melanophore Model of Amyloidβ Toxicity
Publisher: Mary Ann Liebert Inc
Date: 06-2010
Abstract: Reliable animal models are required to facilitate the understanding of neurodegenerative pathways in Alzheimer's disease. Animal models can also be employed to search for disease-modifying drugs. The embryos and larvae of zebrafish are particularly advantageous for this purpose. For Alzheimer's disease, drugs that can ameliorate amyloid beta (A beta) toxicity have therapeutic and/or prophylactic potential. We attempted to generate a zebrafish model of A beta toxicity that would be viable and fertile but have a highly visible pigmentation phenotype in larvae. The larvae could then be arrayed in microtiter plates to screen compound libraries for drugs acting to reduce A beta toxicity. We used the promoter of the zebrafish mitfa (nacre) gene to drive expression of the pathological 42 amino acid species of human A beta, A beta(42), specifically in the highly visible melanophores (melanocytes) of transgenic zebrafish. However, the transgenic fish only showed an aberrant pigment phenotype in adults at the advanced age of 16 months. Nevertheless, our results show that alteration of zebrafish pigment pattern may be useful for analysis of toxic peptide action.
Iron Responsive Element (IRE)-mediated responses to iron dyshomeostasis in Alzheimer’s disease
Publisher: Cold Spring Harbor Laboratory
Date: 03-05-2020
DOI: 10.1101/2020.05.01.071498
Abstract: Iron trafficking and accumulation is associated with Alzheimer’s disease (AD) pathogenesis. However, the role of iron dyshomeostasis in early disease stages is uncertain. Currently, gene expression changes indicative of iron dyshomeostasis are not well characterized, making it difficult to explore these in existing datasets. To identify sets of genes predicted to contain Iron Responsive Elements (IREs) and use these to explore possible iron dyshomeostasis-associated gene expression responses in AD. Comprehensive sets of genes containing predicted IRE or IRE-like motifs in their 3’ or 5’ untranslated regions (UTRs) were identified in human, mouse, and zebrafish reference transcriptomes. Further analyses focusing on these genes were applied to a range of cultured cell, human, mouse, and zebrafish gene expression datasets. IRE gene sets are sufficiently sensitive to distinguish not only between iron overload and deficiency in cultured cells, but also between AD and other pathological brain conditions. Notably, changes in IRE transcript abundance are amongst the earliest observable changes in zebrafish familial AD (fAD)-like brains, preceding other AD-typical pathologies such as inflammatory changes. Unexpectedly, while some IREs in the 3’ untranslated regions of transcripts show significantly increased stability under iron deficiency in line with current assumptions, many such transcripts instead display decreased stability, indicating that this is not a generalizable paradigm. Our results reveal IRE gene expression changes as early markers of the pathogenic process in fAD and are consistent with iron dyshomeostasis as an important driver of this disease. Our work demonstrates how differences in the stability of IRE- containing transcripts can be used to explore and compare iron dyshomeostasis-associated gene expression responses across different species, tissues, and conditions.
Zebrafish aplnra functions in epiboly
Publisher: Springer Science and Business Media LLC
Date: 19-11-2009
Abstract: The zebrafish, Danio rerio , possesses the paralogous genes aplnra and aplnrb that are duplicates of an ancestral orthologue of the human APLNR gene encoding a G-protein coupled receptor that binds the peptide ligand APELIN and is required for normal cardiovascular function. aplnrb is required for migration of cells contributing to heart development in zebrafish embryos. aplnra is transcribed in a complex pattern during early development but its function in embryogenesis is largely unknown. Blockage of translation of aplnra mRNA in zebrafish embryos results in retarded or failed epiboly with the blastoderm apparently disconnected from the nuclei of the yolk syncytial layer. Gastrulation is also defective. Failure of correct tail extension is observed with ectopic structures resembling somites positioned dorsal to the spinal cord. aplnra , unlike its duplicate aplnrb , is essential for normal epiboly, although this function appears to be independent of signalling activated by zebrafish Apelin. The defects in epiboly caused by loss of aplnra activity appear, at least partially, to be due to a requirement for aplnra activity in the yolk syncytial layer.
Cryptic organisation within an apparently irregular rostrocaudal distribution of interneurons in the embryonic zebrafish spinal cord
Publisher: Elsevier BV
Date: 11-2010
DOI: 10.1016/J.YEXCR.2010.06.020
Abstract: The molecules and mechanisms involved in patterning the dorsoventral axis of the developing vertebrate spinal cord have been investigated extensively and many are well known. Conversely, knowledge of mechanisms patterning cellular distributions along the rostrocaudal axis is relatively more restricted. Much is known about the rostrocaudal distribution of motoneurons and spinal cord cells derived from neural crest but there is little known about the rostrocaudal patterning of most of the other spinal cord neurons. Here we report data from our analyses of the distribution of dorsal longitudinal ascending (DoLA) interneurons in the developing zebrafish spinal cord. We show that, although apparently distributed irregularly, these cells have cryptic organisation. We present a novel cell-labelling technique that reveals that DoLA interneurons migrate rostrally along the dorsal longitudinal fasciculus of the spinal cord during development. This cell-labelling strategy may be useful for in vivo analysis of factors controlling neuron migration in the central nervous system. Additionally, we show that DoLA interneurons persist in the developing spinal cord for longer than previously reported. These findings illustrate the need to investigate factors and mechanisms that determine "irregular" patterns of cell distribution, particularly in the central nervous system but also in other tissues of developing embryos.
Evolutionary analysis of vertebrate Notch genes
Publisher: Springer Science and Business Media LLC
Date: 07-2001
Abstract: We have conducted an evolutionary analysis of Notch genes of the vertebrates Danio rerio and Mus musculus to examine the expansion and ersification of the Notch family during vertebrate evolution. The existence of multiple Notch genes in vertebrate genomes suggests that the increase in Notch signaling pathways may be necessary for the additional complexity observed in the vertebrate body plan. However, orthology relationships within the vertebrate Notch family indicate that biological functions are not fixed within orthologous groups. Phylogenetic reconstruction of the vertebrate Notch family suggests that the zebrafish notch1a and 1b genes resulted from a duplication occurring around the time of the teleost/mammalian ergence. There is also evidence that the mouse Notch4 gene is the result of a rapid ergence from a Notch3-like gene. Investigation of the ankyrin repeat region sequences showed there to be little evidence for gene conversion events between repeat units. However, relationships between repeats 2-5 suggest that these repeats are the result of a tandem duplication of a dual repeat unit. Selective pressure on maintenance of ankyrin repeat sequences indicated by relationships between the repeats suggests that specific repeats are responsible for particular biological activities, a finding consistent with mutational studies of the Caenorhabditis elegans gene glp-1. Sequence similarities between the ankyrin repeats and the region immediately C-terminal of the repeats further suggests that this region may be involved in the modulation of ankyrin repeat function.
Nonspecific, Nested Suppression PCR Method for Isolation of Unknown Flanking DNA (Cold-Start Method)
Publisher: Humana Press
Date: 2002
Zebrafish as a tool in Alzheimer's disease research
Publisher: Elsevier BV
Date: 03-2011
DOI: 10.1016/J.BBADIS.2010.09.012
Abstract: Alzheimer's disease is the most prevalent form of neurodegenerative disease. Despite many years of intensive research our understanding of the molecular events leading to this pathology is far from complete. No effective treatments have been defined and questions surround the validity and utility of existing animal models. The zebrafish (and, in particular, its embryos) is a malleable and accessible model possessing a vertebrate neural structure and genome. Zebrafish genes orthologous to those mutated in human familial Alzheimer's disease have been defined. Work in zebrafish has permitted discovery of unique characteristics of these genes that would have been difficult to observe with other models. In this brief review we give an overview of Alzheimer's disease and transgenic animal models before examining the current contribution of zebrafish to this research area. This article is part of a Special Issue entitled Zebrafish Models of Neurological Diseases.
Evolutionary and Expression Analysis of the Zebrafish Deubiquitylating Enzyme, Usp9
Publisher: Mary Ann Liebert Inc
Date: 08-2007
Abstract: Mouse Usp9x/Fam (fat facets in mouse) and its Drosophila ortholog faf (fat facets) encode substrate-specific deubiquitylating enzymes and are essential for early embryonic development. The zebrafish (Danio rerio) is a powerful tool for studying embryonic gene expression patterns and function, and to that end, we sought to characterize the zebrafish Usp9 ortholog. Zebrafish usp9 was identified from database searches, and the predicted Usp9 protein is very highly conserved in mouse (90% identical and 94% similar) over its entire length. Phylogenetic analysis indicated that vertebrate Usp9s are highly clustered and separate from the USP9Y and Drosophila forms. We examined the developmental expression of usp9 from fertilization to 2 days postfertilization. usp9 is initially expressed ubiquitously but later restricted to the cephalic central nervous system, the developing lens, distal tips of the pectoral fin bud, and migrating endoderm. The extraordinary level of conservation between the mouse and zebrafish genes, coupled with equivalent expression patterns, makes zebrafish an appropriate complementary system for the study of usp9 in development.
Characterization and Developmental Expression of the Amphioxus Homolog of Notch (AmphiNotch): Evolutionary Conservation of Multiple Expression Domains in Amphioxus and Vertebrates
Publisher: Elsevier BV
Date: 05-2001
The evolved divergence of γ-secretase-susceptibility of homologous proteins Ngfrb and Nradd in zebrafish
Publisher: Springer Science and Business Media LLC
Date: 12-2021
DOI: 10.1186/S13104-021-05876-2
Abstract: NGFR 75NTR and NRADD/NRH proteins are closely related structurally and are encoded by genes that arose from a duplication event early in vertebrate evolution. The transmembrane domain (TMD) of NGFR is cleaved by γ-secretase but there is conflicting data around the susceptibility to γ-secretase cleavage of NRADD proteins. If NGFR and NRADD show differential susceptibility to γ-secretase, then they can be used to dissect the structural constraints determining substrate susceptibility. We sought to test this differential susceptibility. We developed labelled, lumenally-truncated forms of zebrafish Ngfrb and Nradd and a chimeric protein in which the TMD of Nradd was replaced with the TMD of Ngfrb. We expressed these in zebrafish embryos to test their susceptibility to γ-secretase cleavage by monitoring their stability using western immunoblotting. Inhibition of γ-secretase activity using DAPT increased the stability of only the Ngfrb construct. Our results support that only NGFR is cleaved by γ-secretase. Either NGFR evolved γ-secretase-susceptibility since its creation by gene duplication, or NRADD evolved to be refractory to γ-secretase. Protein structure outside of the TMD of NGFR is likely required for susceptibility to γ-secretase.
Transgenic Zebrafish Recapitulating tbx16 Gene Early Developmental Expression
Publisher: Public Library of Science (PLoS)
Date: 24-06-2011
Comparative analysis of Alzheimer’s disease knock-in model brain transcriptomes implies changes to energy metabolism as a causative pathogenic stress
Publisher: Cold Spring Harbor Laboratory
Date: 17-02-2021
DOI: 10.1101/2021.02.16.431539
Abstract: Energy production is the most fundamentally important cellular activity supporting all other functions, particularly in highly active organs such as brains. Here, we summarise transcriptome analyses of young adult (pre-disease) brains from a collection of eleven early-onset familial Alzheimer’s disease (EOfAD)-like and non-EOfAD-like mutations in three zebrafish genes. The one cellular activity consistently predicted as affected by only the EOfAD-like mutations is oxidative phosphorylation that produces most of the brain’s energy. All the mutations were predicted to affect protein synthesis. We extended our analysis to knock-in mouse models of APOE alleles and found the same effect for the late onset Alzheimer’s disease risk allele ɛ4. Our results support a common molecular basis for initiation of the pathological processes leading to both early and late onset forms of Alzheimer’s disease and illustrate the utility of both zebrafish and knock-in, single EOfAD mutation models for understanding the causes of this disease.
HMGA1 zebrafish co-orthologue hmga1b can modulate p53-dependent cellular responses but is unable to control the alternative splicing of psen1
Publisher: Cold Spring Harbor Laboratory
Date: 02-01-2018
DOI: 10.1101/241927
Abstract: The HIGH MOBILITY GROUP AT-HOOK 1 (HMGA1) family of chromatin-binding proteins plays important roles in cellular responses to low oxygen. HMGA1 proteins regulate gene activity both in the nucleus and within mitochondria. They are expressed mainly during embryogenesis and their upregulation in cancerous cells indicates poor prognosis. The human HMGA1a isoform is upregulated under hypoxia via oxidative stress-dependent signalling and can then bind nascent transcripts of the familial Alzheimer’s disease gene PSEN2 to regulate alternative splicing to produce the truncated PSEN2 protein isoform PS2V. Zebrafish where hmga1a expression is induced by hypoxia to control splicing of the psen1 gene to produce the PS2V-equivalent isoform PS1IV. Zebrafish possess a second gene with apparent HMGA1 orthology, hmga1b. Here we investigate the predicted structure of Hmga1b protein and demonstrate it to be co-orthologous to human HMGA1 and most similar in structure to human isoform HMGA1c. We show that forced over-expression of either hmga1a or hmga1b mRNA can suppress the action of the cytotoxin hydroxyurea in stimulating cell death and transcription of the genes mdm2 and cdkn1a that, in humans, are controlled by p53. Our experimental data support an important role for HMGA1 proteins in modulation of p53-dependent responses and illuminate the evolutionary subfunctionalisation.
The evolutionary relationships of zebrafish genes tbx6 , tbx16 / spadetail and mga
Publisher: Springer Science and Business Media LLC
Date: 10-2003
DOI: 10.1007/S00427-003-0348-2
Abstract: The T-box (Tbx) genes encode a family of transcription factors required for development of vertebrate embryos. In an attempt to discover human orthologues of the zebrafish (Danio rerio) tbx6 and tbx16/spadetail genes, we found that the most similar human (Homo sapiens) gene is the orthologue of mouse (Mus musculus) Mga (MAX gene associated). We have identified the zebrafish orthologue of Mga using analyses of sequence similarity and the orthologies of syntenic genes. Zebrafish mga maps close to dtk (developmental receptor tyrosine kinase), the orthologue of human TYRO3 (TYRO3 protein tyrosine kinase). Like its human and mouse orthologues, zebrafish mga lacks the three conserved introns within the T-box coding sequences that are characteristic of the vertebrate T-box gene family. This suggests that these genes are derived from an ancient reverse transcription event. The human genome does not appear to possess orthologues of zebrafish tbx6 or tbx16/spadetail.
Robust homeostasis of Presenilin1 protein levels by transcript regulation
Publisher: Elsevier BV
Date: 06-2012
DOI: 10.1016/J.NEULET.2012.04.064
Abstract: The Presenilin proteins are essential facilitators of numerous developmental and cell signaling pathways. Point mutations in the human PRESENILIN genes (including mutations affecting splicing) have been linked to familial Alzheimer's disease. Zebrafish possess orthologues of the human PRESENILIN1 and PRESENILIN2 genes. We previously investigated forced aberrant splicing of zebrafish presenilin1 and discovered that high levels of incorporation into spliced transcripts of the intron cognate with human PRESENILIN1 intron 8 resulted in little or no change in Presenilin1 protein level and no identifiable embryonic phenotype. We now demonstrate that zebrafish embryos maintain relatively stable levels of normal Presenilin1 transcript and protein despite accumulating large amounts of aberrantly spliced presenilin1 transcript. We also show that increasing the levels of Presenilin1 protein decreases normal presenilin1 transcription. These two independent lines of evidence and the fact that blockage of Presenilin1 translation increases presenilin1 transcription support that regulation of presenilin1 transcript levels plays a major role in the homeostasis of Presenilin1 protein levels, presumably via a feedback mechanism that monitors the levels of Presenilin1 protein.
Differential allelic representation (DAR) identifies candidate eQTLs and improves transcriptome analysis
Publisher: Cold Spring Harbor Laboratory
Date: 02-03-2023
DOI: 10.1101/2023.03.02.530865
Abstract: In comparisons between mutant and wild-type genotypes, transcriptome analysis can reveal the direct impacts of a mutation, together with the homeostatic responses of the biological system. Recent studies have highlighted that, when homozygous mutations are studied in non-isogenic backgrounds, genes from the same chromosome as a mutation often appear over-represented among differentially expressed (DE) genes. One hypothesis suggests that DE genes chromosomally linked to a mutation may not reflect true biological responses to the mutation but, instead, result from differences in representation of expression quantitative trait loci (eQTLs) between s le groups selected on the basis of mutant or wild-type genotype. This is problematic when inclusion of spurious DE genes in a functional enrichment study results in incorrect inferences of mutation effect. Here we show that chromosomally co-located differentially expressed genes (CC-DEGs) can also be observed in analyses of dominant mutations in heterozygotes. We define a method and a metric to quantify, in RNA-sequencing data, localised differential allelic representation (DAR) between groups of s les subject to differential expression analysis. We show how the DAR metric can predict regions prone to eQTL-driven differential expression, and how it can improve functional enrichment analyses through gene exclusion or weighting of gene-level rankings. Advantageously, this improved ability to identify probable eQTLs also reveals ex les of CC-DEGs that are likely to be functionally related to a mutant phenotype. This supports a long-standing prediction that selection for advantageous linkage disequilibrium influences chromosome evolution. By comparing the genomes of zebrafish ( Danio rerio ) and medaka ( Oryzias latipes ), a teleost with a conserved ancestral karyotype, we find possible ex les of chromosomal aggregation of CC-DEGs during evolution of the zebrafish lineage. The DAR metric provides a solid foundation for addressing the eQTL issue in new and existing datasets because it relies solely on RNA-sequencing data.
Motch A and Motch B—Two Mouse Notch Homologues Coexpressed in a Wide Variety of Tissues
Publisher: Elsevier BV
Date: 02-1993
Abstract: Notch is one of the neurogenic genes of Drosophila controlling the decision between ectodermal and neural fate for cells in the early embryo. We have used a polymerase chain reaction (PCR)-based strategy to identify cDNA clones representing two mouse homologues to the Drosophila Notch gene. One of the genes, Motch A, is the mouse orthologue to the previously cloned Notch genes in Xenopus, rat, and man. The other gene, Motch B, is more distantly related to the characterized vertebrate Notch genes, but of equal homology to the Drosophila Notch as is Motch A, and therefore represents a distinct branch of a vertebrate Notch gene family. The Motch A and Motch B branches probably arose by gene duplication early in vertebrate evolution. Both Motch A and Motch B retain the same principal structure, encode mRNAs of approximately 10 kilobases, are expressed during mouse embryogenesis, and have largely overlapping expression patterns in adult tissues. We discuss possible consequences of expressing two closely related Notch homologues in the same set of tissues in terms of cell-cell signaling and differentiation control.
Discriminatory Frontier policy
Publisher: Springer Science and Business Media LLC
Date: 07-1995
DOI: 10.1038/376012B0
An Alternative View of Familial Alzheimer’s Disease Genetics
Publisher: MDPI AG
Date: 23-04-2023
DOI: 10.20944/PREPRINTS202303.0476.V2
Abstract: Probabilistic and parsimony-based arguments regarding available genetics data are used to propose that Hardy and Higgin& rsquo s amyloid cascade hypothesis is valid but is commonly interpreted too narrowly to support, incorrectly, the primacy of the amyloid beta peptide (A& beta ) in driving Alzheimer& rsquo s disease pathogenesis. Instead, increased activity of the & beta CTF (C99) fragment of APP is likely the critical pathogenic determinant altered by mutations in the APP gene. This model is consistent with the regulation of APP mRNA translation via its 5& rsquo iron responsive element (IRE). Similar arguments support that the pathological effects of familial Alzheimer& rsquo s disease mutations in the genes PSEN1 and PSEN2 are not exerted directly via changes in APP cleavage to produce different ratios of A& beta length. Rather, these mutations likely affect the stability of presenilin holoprotein and/or & gamma -secretase multimers with consequences for & gamma -secretase activity and other important cellular functions. All fAD mutations in APP, PSEN1, and PSEN2 likely find unity of pathological mechanism in their actions on endolysosomal acidification and mitochondrial function, with detrimental effects on iron homeostasis and promotion of & seudo-hypoxia& being of central importance. A& beta production is enhanced and distorted by oxidative stress and accumulates due to decreased lysosomal function. It may act as a disease-associated molecular pattern (DAMP) enhancing oxidative stress-driven neuroinflammation during the cognitive phase of the disease. We also discuss fascinating, but largely ignored, data on presenilin biology that may be important in understanding presenilins& rsquo central role in familial Alzheimer& rsquo s disease.
An Alternative View of Familial Alzheimer’s Disease Genetics
Publisher: MDPI AG
Date: 28-03-2023
DOI: 10.20944/PREPRINTS202303.0476.V1
Abstract: A probabilistic and parsimony-based view of available genetics data is presented to argue that Hardy and Higgins& rsquo amyloid cascade hypothesis is valid but is commonly misinterpreted to support, incorrectly, the primacy of the amyloid beta peptide (A& beta ) in driving Alzheimer& rsquo s disease pathogenesis. Similar means are used to argue that the pathological effects of familial Alzheimer& rsquo s disease mutations in the genes PSEN1 and PSEN2 are not exerted directly via changes in APP cleavage to produce different ratios of A& beta length. Instead, increase in the activity of the bCTF (C99) fragment of APP is likely the critical pathogenic determinant altered by mutations in the APP gene. This model is consistent with the regulation of APP mRNA translation via its 5& rsquo iron responsive element (IRE). Familial Alzheimer& rsquo s disease (fAD) mutations in PSEN1 and PSEN2 likely affect the stability of presenilin holoprotein and/or & gamma -secretase multimers with consequences for & gamma -secretase activity and other important cellular functions. All fAD mutations in APP, PSEN1, and PSEN2 likely find unity of pathological mechanism in their actions on endolysosomal acidification and mitochondrial function, with detrimental effects on iron homeostasis and promotion of & seudo-hypoxia& being of central importance. A& beta production is enhanced and distorted by oxidative stress and accumulates due to decreased lysosomal function. It may act as a disease-associated molecular pattern (DAMP) enhancing oxidative stress-driven neuroinflammation during the cognitive phase of the disease. We also discuss fascinating, but largely ignored, data on presenilin biology that may be important in understanding presenilins& rsquo central role in familial Alzheimer& rsquo s disease.
Nestin mRNA expression correlates with the central nervous system progenitor cell state in many, but not all, regions of developing central nervous system
Publisher: Elsevier BV
Date: 1995
DOI: 10.1016/0165-3806(94)00162-S
Abstract: Nestin is a recently discovered intermediate filament (IF) gene. Nestin expression has been extensively used as a marker for central nervous system (CNS) progenitor cells in different contexts, based on observations indicating a correlation between nestin expression and this cell type in vivo. To evaluate this correlation in more detail nestin mRNA expression in developing and adult mouse CNS was analysed by in situ hybridization. We find that nestin is expressed from embryonic day (E) 7.75 and that expression is detected in many proliferating CNS regions: at E10.5 nestin is expressed in cells of both the rostral and caudal neural tube, including the radial glial cells at E15.5 and postnatal day (P) 0 expression is observed largely in the developing cerebellum and in the ventricular and subventricular areas of the developing telencephalon. Furthermore, the transition from a proliferating to a post-mitotic cell state is accompanied by a rapid decrease in nestin mRNA for motor neurons in the ventral spinal cord and for neurons in the marginal layer of developing telencephalon. In contrast to these data we observe two proliferating areas, the olfactory epithelium and the precursor cells of the hippoc al granule neurons, which do not express nestin at detectable levels. Thus, nestin mRNA expression correlates with many, but not all, regions of proliferating CNS progenitor cells. In addition to its temporal and spatial regulation nestin expression also appears to be regulated at the level of subcellular mRNA localization: in columnar neuroepithelial and radial glial cells nestin mRNA is predominantly localized to the pial endfeet.
Expression of Notch 1, 2 and 3 is regulated by epithelial-mesenchymal interactions and retinoic acid in the developing mouse tooth and associated with determination of ameloblast cell fate.
Publisher: Rockefeller University Press
Date: 15-07-1995
Abstract: Notch 1, Notch 2, and Notch 3 are three highly conserved mammalian homologues of the Drosophila Notch gene, which encodes a transmembrane protein important for various cell fate decisions during development. Little is yet known about regulation of mammalian Notch gene expression, and this issue has been addressed in the developing rodent tooth during normal morphogenesis and after experimental manipulation. Notch 1, 2, and 3 genes show distinct cell-type specific expression patterns. Most notably, Notch expression is absent in epithelial cells in close contact with mesenchyme, which may be important for acquisition of the ameloblast fate. This reveals a previously unknown prepatterning of dental epithelium at early stages, and suggests that mesenchyme negatively regulates Notch expression in epithelium. This hypothesis has been tested in homo- and heterotypic explant experiments in vitro. The data show that Notch expression is downregulated in dental epithelial cells juxtaposed to mesenchyme, indicating that dental epithelium needs a mesenchyme-derived signal in order to maintain the downregulation of Notch. Finally, Notch expression in dental mesenchyme is upregulated in a region surrounding beads soaked in retinoic acid (50-100 micrograms/ml) but not in fibroblast growth factor-2 (100-250 micrograms/ml). The response to retinoic acid was seen in explants of 11-12-d old mouse embryos but not in older embryos. These data suggest that Notch genes may be involved in mediating some of the biological effects of retinoic acid during normal development and after teratogenic exposure.
Evolutionary analysis of vertebrate Notch genes
Publisher: Springer Science and Business Media LLC
Date: 04-2002
Huntingtin-deficient zebrafish exhibit defects in iron utilization and development.
Publisher: Oxford University Press (OUP)
Date: 13-06-2007
DOI: 10.1093/HMG/DDM138
Abstract: Huntington's disease (HD) is one of nine neurodegenerative disorders caused by expansion of CAG repeats encoding polyglutamine in their respective, otherwise apparently unrelated proteins. Despite these proteins having widespread and overlapping expression patterns in the brain, a specific and unique subset of neurons exhibits particular vulnerability in each disease. It has been hypothesized that perturbation of normal protein function contributes to the specificity of neuronal vulnerability however, the normal biological functions of many of these proteins including the HD gene product, Huntingtin (Htt), are unclear. To explore the roles of Htt, we have used antisense morpholino oligonucleotides to observe the effects of Htt deficiency in early zebrafish development. Knockdown of Htt expression resulted in a variety of developmental defects. Most notably, Htt-deficient zebrafish had hypochromic blood due to decreased hemoglobin production, despite the presence of iron within blood cells. Furthermore, transferrin receptor 1 transcripts were increased, suggesting cellular iron starvation. Provision of iron to the cytoplasm in a bio-available form restored hemoglobin production in Htt-deficient embryos. Since erythroid cells acquire iron via receptor-mediated endocytosis of transferrin, these results suggest a role for Htt in making endocytosed iron accessible for cellular utilization. Iron is required for oxidative energy production, and defects in iron homeostasis and energy metabolism are features of HD pathogenesis that are most pronounced in the major region of neurodegeneration. It is therefore plausible that perturbation of Htt's normal role in the iron pathway (by polyglutamine tract expansion) contributes to HD pathology, and particularly to its neuronal specificity.
The protein tyrosine phosphatase Pez regulates TGFβ, epithelial-mesenchymal transition, and organ development
Publisher: Rockefeller University Press
Date: 24-09-2007
Abstract: Epithelial–mesenchymal transition (EMT), crucial during embryogenesis for new tissue and organ formation, is also considered to be a prerequisite to cancer metastasis. We report here that the protein tyrosine phosphatase Pez is expressed transiently in discrete locations in developing brain, heart, pharyngeal arches, and somites in zebrafish embryos. We also find that Pez knock-down results in defects in these organs, indicating a crucial role in organogenesis. Overexpression of Pez in epithelial MDCK cells causes EMT, with a drastic change in cell morphology and function that is accompanied by changes in gene expression typical of EMT. Transfection of Pez induced TGFβ signaling, critical in developmental EMT with a likely role also in oncogenic EMT. In zebrafish, TGFβ3 is co- expressed with Pez in a number of tissues and its expression was lost from these tissues when Pez expression was knocked down. Together, our data suggest Pez plays a crucial role in organogenesis by inducing TGFβ and EMT.
Expression Analysis of a Tyrosinase Promoter Sequence in Zebrafish
Publisher: Wiley
Date: 05-03-2003
DOI: 10.1034/J.1600-0749.2003.00002.X
Abstract: Sequence comparisons and functional analysis of the 5' upstream regions of tyrosinase genes have revealed the importance of cis-regulatory elements acting to control the spatiotemporal expression of tyrosinase in the melanocytes and retinal pigmented epithelium of developing embryos. To date there are no reports addressing the control of tyrosinase gene transcription in zebrafish, a vertebrate model organism of increasing importance. To exploit the tyrosinase gene as a marker in zebrafish we set out to clone its promoter and analyse its regulation during embryogenesis. Amplification of a zebrafish tyrosinase complementary DNA fragment by reverse transcriptase polymerase chain reaction allowed us to isolate and sequence a 1041 nt genomic DNA fragment that includes a transcription initiation site and 73 nt of the open reading frame. Bioinformatic analysis of this genomic sequence revealed five E-box motifs, including one CATGTG type E-box present in a putative initiation region. These are conserved positive regulatory elements in vertebrate tyrosinase promoters. We show that a region of 814 nt upstream from the translation start site of the zebrafish tyrosinase gene can drive expression in retinal pigmented epithelium in transiently transgenic zebrafish embryos but that its activity is not restricted to melanin-producing cells. This region is unable to drive transcription in human melanoma cell lines. Ectopic expression from this zebrafish tyrosinase promoter fragment is probably due to the absence of positive and negative cis-regulatory elements, such as a tyrosinase distal element, which is known to function as a pigment cell-specific enhancer.
Synthesis in Escherichia coli of the major glycoprotein of human rotavirus: analysis of the antigenic regions
Publisher: Elsevier BV
Date: 12-1989
DOI: 10.1016/0378-1119(89)90141-8
Abstract: Various regions of the gene encoding the major neutralization antigen, VP7, of human rotavirus have been expressed in Escherichia coli, as N-terminal fusions to beta-galactosidase under the control of the lac promoter. We have determined that the fusion products of two clones containing regions AB (aa 69-158) and ABC (aa 69-319) were antigenic, reacting with antibodies raised against whole virus. When guinea pigs were immunized with fusion protein purified by monoclonal antibody affinity columns, no neutralizing or virus-binding antibodies were detected, but antibodies binding to denatured VP7 were present.
Scientists need to confront economists about peak oil
Publisher: Springer Science and Business Media LLC
Date: 03-2007
DOI: 10.1038/446257B
PRESENILIN 1mutations causing early-onset familial Alzheimer’s disease or familial acne inversa differ in their effects on genes facilitating energy metabolism and signal transduction
Publisher: Cold Spring Harbor Laboratory
Date: 27-01-2021
DOI: 10.1101/2021.01.26.428321
Abstract: The most common cause of early-onset familial Alzheimer’s disease (EOfAD) is mutations in PRESENILIN 1 ( PSEN1 ) allowing production of mRNAs encoding full-length, but mutant, proteins. In contrast, a single known frameshift mutation in PSEN1 causes familial acne inversa (fAI) without EOfAD. The molecular consequences of heterozygosity for these mutation types, and how they cause completely different diseases, remains largely unexplored. To analyse brain transcriptomes of young adult zebrafish to identify similarities and differences in the effects of heterozygosity for psen1 mutations causing EOfAD or fAI. RNA sequencing was performed on mRNA isolated from the brains of a single family of 6-month-old zebrafish siblings either wild type or possessing a single, heterozygous EOfAD-like or fAI-like mutation in their endogenous psen1 gene. Both mutations downregulate genes encoding ribosomal subunits, and upregulate genes involved in inflammation. Genes involved in energy metabolism appeared significantly affected only by the EOfAD-like mutation, while genes involved in Notch, Wnt and neurotrophin signalling pathways appeared significantly affected only by the fAI-like mutation. However, investigation of direct transcriptional targets of Notch signalling revealed possible increases in γ-secretase activity due to heterozygosity for either psen1 mutation. Transcriptional adaptation due to the fAI-like frameshift mutation was evident. We observed both similar and contrasting effects on brain transcriptomes of the heterozygous EOfAD-like and fAI-like mutations. The contrasting effects may illuminate how these mutation types cause distinct diseases.
Differential effects of loss of park7 activity on Iron Responsive Element (IRE) gene sets: Implications for the role of iron dyshomeostasis in the pathophysiology of Parkinson’s disease
Publisher: Cold Spring Harbor Laboratory
Date: 27-03-2021
DOI: 10.1101/2021.03.25.437102
Abstract: Mutation of the gene PARK7 ( DJ1 ) causes monogenic autosomal recessive Parkinson’s disease (PD) in humans. Subsequent alterations of PARK7 protein function lead to mitochondrial dysfunction, a major element in PD pathology. Homozygous mutants for the PARK7 -orthologous genes in zebrafish, park7 , show changes to gene expression in the oxidative phosphorylation pathway, supporting that disruption of energy production is a key feature of neurodegeneration in PD. Iron is critical for normal mitochondrial function, and we have previously used bioinformatic analysis of IRE-bearing transcripts in brain transcriptomes to find evidence supporting the existence of iron dyshomeostasis in Alzheimer’s disease. Here, we analysed IRE-bearing transcripts in the transcriptome data from homozygous park7 −/− mutant zebrafish brains. We found that the set of genes with “high quality” IREs in their 5’ untranslated regions (UTRs, the HQ5’IRE gene set) was significantly altered in these 4-month-old park7 −/− brains. However, sets of genes with IREs in their 3’ UTRs appeared unaffected. The effects on HQ5’IRE genes are possibly driven by iron dyshomeostasis and/or oxidative stress, but illuminate the existence of currently unknown mechanisms with differential overall effects on 5’ and 3’ IREs.
Expression of three zebrafish orthologs of human FMR1-related genes and their phylogenetic relationships
Publisher: Springer Science and Business Media LLC
Date: 17-09-2004
DOI: 10.1007/S00427-004-0438-9
Abstract: The human fragile X mental retardation syndrome is caused by expansions of a CGG repeat in the FMR1 gene. FXR1 and FXR2 are autosomal paralogs of FMR1. The products of the three genes, FMRP, FXR1P, and FXR2P, respectively, belong to a family of RNA-binding proteins. While the FMR1-related gene family is well described in human, mouse and Drosophila, little is known about zebrafish (Danio rerio) orthologs of these genes. Here we collate the known FMR1-related gene sequences from zebrafish, examine their regions of structural conservation, and define their orthologies with the human genes. We demonstrate that zebrafish possess only three FMR1-related genes, fmr1, fxr1 and fxr2, and these are orthologous to the human FMR1, FXR1 and FXR2 genes respectively. We examine the spatiotemporal pattern of transcription of the zebrafish genes from 0 hours post fertilisation (hpf) until 24 hpf. Expression of fmr1, fxr1 and fxr2 is widespread throughout this time. However, relative to surrounding tissues, expression of fxr2 is raised in adaxial and somitic cells by 12 hpf while fxr1 expression is high in the anterior of the embryo, and is raised in adaxial cells by 12 hpf. Distinct patterns (and levels) of expression are seen for the different genes later in development. At 24 hpf, fxr1 and fxr2 transcripts show complex distribution patterns in somites. The expression of the FMR1-related gene family in zebrafish tissues is broadly consistent with expression in mouse and human, supporting the idea that zebrafish should be an excellent model organism in which to study the functions of the vertebrate FMR1-related gene family.
Peeking at Peak Oil
Publisher: Springer New York
Date: 2012
A hyperactive sleeping beauty transposase enhances transgenesis in zebrafish embryos
Publisher: Springer Science and Business Media LLC
Date: 04-11-2010
The novel Notch homologue mouse Notch 3 lacks specific epidermal growth factor-repeats and is expressed in proliferating neuroepithelium
Publisher: Elsevier BV
Date: 05-1994
DOI: 10.1016/0925-4773(94)90081-7
Abstract: In Drosophila, the Notch gene is pivotal for cell fate decisions at many stages of development and, in particular, during the formation of the nervous system. Absence of Notch results in the generation of excessive numbers of neural cells at the expense of epidermal cells. Two previously identified mammalian Notch homologous encode all the principal features of the Drosophila gene, e.g. 36 EGF-repeats and 3 Notch/lin-12 repeats extracellularly and 6 intracellular cdc10/SWI6 repeats. We report here the characterisation of a third mammalian homologue, mouse Notch 3, which shares the same remarkable conservation relative to the Drosophila gene as the two previously identified homologues, but with three important distinctions. First, Notch 3 specifically lacks the equivalent of EGF-repeat 21 second, it lacks an EGF-repeat-sized region comprising parts of EGF-repeats 2 and 3 and third, it encodes a considerably shorter intracellular domain. The Notch 3 gene is expressed at high levels in proliferating neuroepithelium and expression is downregulated at later stages. The expression patterns of the Notch 1, 2 and 3 genes are quite distinct during central nervous system (CNS) development, and all possible combinations of expression, i.e. none, one, two, or all three genes, are seen, suggesting a combinatorial code of Notch function in mammals. Considering the predominantly early expression in CNS and its distinct structural features, the Notch 3 gene is likely to contribute significantly to vertebrate Notch function during CNS development.
Selective neuronal requirement for huntingtin in the developing zebrafish.
Publisher: Oxford University Press (OUP)
Date: 29-09-2009
DOI: 10.1093/HMG/DDP455
Regular care and maintenance of a Zebrafish (Danio rerio) laboratory: An introduction
Publisher: MyJove Corporation
Date: 18-11-2012
DOI: 10.3791/4196
The identity and distribution of neural cells expressing the mesodermal determinant spadetail
Publisher: Springer Science and Business Media LLC
Date: 18-07-2002
Abstract: The spadetail (spt) gene of zebrafish is expressed in presomitic mesoderm and in neural cells previously suggested to be Rohon-Beard neurons. The mechanism(s) generating the apparently irregular rostrocaudal distribution of spt-expressing cells in the developing CNS is unknown. spt-expressing neural cells co-express huC, a marker of neurons. These cells also co-express the genes islet-1, -2 and -3 but not valentino. The islet-1 gene expression, irregular distribution and dorsolateral position of spt-expressing cells in the developing CNS are characteristic of dorsal longitudinal ascending (DoLA) interneurons. Shortly after their birth, these neurons extend processes rostrally into which spt mRNA is transported. At 24 hours post fertilisation(hpf), spt-expressing neurons occur most frequently at rostral levels caudal of the 5th-formed somite pair. There is no apparent bias in the number of spt-expressing cells on the left or right sides of embryos. Extended staining for spt-transcription reveals expression in the dorsocaudal cells of somites at the same dorsoventral level as the spt-expressing neurons. There is frequent juxtaposition of spt-expression in newly formed somites and in neurons. This suggests that both types of spt-expressing cell respond to a common positional cue or that neurons expressing spt are patterned irregularly by flanking somitic mesoderm. spt-expressing cells in the developing CNS appear to be DoLA interneurons. The irregular distribution of these cells along the rostrocaudal axis of the spinal cord may be due to "inefficient" patterning of neural spt expression by a signal(s) from flanking, regularly distributed somites also expressing spt.
Accelerated loss of hypoxia response in zebrafish with familial Alzheimer’s disease-like mutation of Presenilin 1
Publisher: Cold Spring Harbor Laboratory
Date: 21-01-2019
DOI: 10.1101/526277
Abstract: Ageing is the major risk factor for Alzheimer’s disease (AD), a condition involving brain hypoxia. The majority of early onset familial AD (EOfAD) cases involve dominant mutations in the gene PSEN1. PSEN1 null mutations do not cause EOfAD. We exploited putative hypomorphic and EOfAD-like mutations in the zebrafish psen1 gene to explore the effects of age and genotype on brain responses to acute hypoxia. Both mutations accelerate age-dependent changes in hypoxia-sensitive gene expression supporting that ageing is necessary, but insufficient, for AD occurrence. Curiously, the responses to acute hypoxia become inverted in extremely aged fish. This is associated with an apparent inability to upregulate glycolysis. Wild type PSEN1 allele expression is reduced in post-mortem brains of human EOfAD mutation carriers (and extremely aged fish), possibly contributing to EOfAD pathogenesis. We also observed that age-dependent loss of HIF1 stabilisation under hypoxia is a phenomenon conserved across vertebrate classes.
pHAPE: a plasmid for production of DNA size marker ladders for gel electrophoresis
Publisher: Cold Spring Harbor Laboratory
Date: 04-11-2022
DOI: 10.1101/2022.11.04.515137
Abstract: DNA size markers (also known as “molecular weight markers” or “DNA ladders”) are an essential tool when using gel electrophoresis to identify and purify nucleic acids. However, the cost of these DNA ladders is not insignificant and, over time, impinges on the funds available for research and training in molecular biology. Here, we describe a method for the generation of “pHAPE”, a plasmid from which a variety of DNA ladders can be generated via simple restriction enzyme digestions. The pHAPE plasmid can be generated by mutagenesis of the commonly used pBluescript II SK+ phagemid followed by insertion of a custom 7,141 bp sequence (made up of three smaller fragments). Our use of pHAPE allows us some small relief from the ever-rising costs of performing molecular biology experiments (“Don’t worry, pHAPE”).
Mining the Data on Coal
Publisher: American Association for the Advancement of Science (AAAS)
Date: 15-05-2009
Identification and expression analysis of the zebrafish orthologues of the mammalian MAP1LC3 gene family
Publisher: Elsevier BV
Date: 10-2014
DOI: 10.1016/J.YEXCR.2014.07.014
Abstract: Autophagy is the principle pathway within cells involved in clearing damaged proteins and organelles. Therefore autophagy is necessary to maintain the turnover balance of peptides and homoeostasis. Autophagy occurs at basal levels under normal conditions but can be upregulated by chemical inducers or stress conditions. The zebrafish (Danio rerio) serves as a versatile tool to understand the functions of genes implicated in autophagy. We report the identification of the zebrafish orthologues of mammalian genes MAP1LC3A (map1lc3a) and MAP1LC3B (map1lc3b) by phylogenetic and conserved synteny analysis and we examine their expression during embryonic development. The zebrafish map1lc3a and map1lc3b genes both show maternally contributed transcripts in early embryogenesis. However, levels of map1lc3a transcript steadily increase until at least 120h post-fertilisation while the levels of map1lc3b show a more variable pattern across developmental time. We have also validated the LC3I ratio/LC3I immunoblot autophagy assay in the presence of chloroquine (a lysosomal proteolysis inhibitor). We found that the LC3II/LC3I ratio is significantly increased in the presence of sodium azide with chloroquine supporting that hypoxia induces autophagy in zebrafish. This was supported by our qPCR assay that showed increased map1lc3a transcript levels in the presence of sodium azide. In contrast, levels of map1lc3b transcripts were reduced in the presence of rapamycin but the decrease in the presence of sodium azide did not reach statistical significance. Our study supports the use of zebrafish for analysing the interplay between hypoxia, development and autophagy.
Multiple learning and administrative advantages when an advanced course in genetics adopted a “flipped-classroom” format with continuous, online assessment
Publisher: Center for Open Science
Date: 05-05-2021
Abstract: We instituted a flipped-classroom learning environment for teaching advanced undergraduate genetics that consisted of pre-recorded lecture material followed by face to face workshops. Student engagement was promoted, and learning reinforced, by a recursive arrangement of electronically delivered formative and summative multiple choice question assessment in every workshop instead of a final end of semester examination. Our teaching approach dramatically increased student attendance, and student engagement with instructors. It simplified examination administration, and adapted easily to the online-only requirements of the SARS-CoV2 pandemic of 2020. The majority of student feedback regarding the revised learning format was positive.
Expression of the Notch 3 intracellular domain in mouse central nervous system progenitor cells is lethal and leads to disturbed neural tube development
Publisher: Elsevier BV
Date: 10-1996
DOI: 10.1016/0925-4773(96)00589-8
Abstract: Notch-like receptors are found in organisms ranging from nematodes to mammals. In Drosophila, Notch plays a key role in cell fate decisions in the early nervous system. In this report we analyse the effects of excess Notch 3 activity in central nervous system (CNS) progenitor cells. A mutated Notch gene encoding the intracellular domain of mouse Notch 3 transcribed from the nestin promoter was expressed in CNS progenitor cells in transgenic mice. This mutation resulted in a phenotypic series of neural tube defects in embryonic day 10.5-12.5 embryos and proved lethal to embryos beyond this age. In the milder phenotype the neural tube displayed a zig-zag morphology and the CNS was slightly enlarged. More severely affected embryos showed a lack of closure of the anterior neural pore, resulting in the externalization of neural tissue and the complete collapse of the third and fourth ventricles. The expanded ventricular zone of the neuroepithelium, a correspondingly enlarged area of nestin expression, and an increase in the number of proliferating cells in the neural tube suggested that these phenotypes resulted from an expanded CNS progenitor cell population. These data provide support in vivo for the notion that Notch activity plays a role in mammalian CNS development and may be required to guide CNS progenitor cells in their choice between continued proliferation or neuronal differentiation.
pHAPE: a plasmid for production of DNA size marker ladders for gel electrophoresis
Publisher: Oxford University Press (OUP)
Date: 2023
DOI: 10.1093/BIOMETHODS/BPAD015
Abstract: DNA size markers (also known as ‘molecular weight markers’ or ‘DNA ladders’) are an essential tool when using gel electrophoresis to identify and purify nucleic acids. However, the cost of these DNA ladders is not insignificant and, over time, impinges on the funds available for research and training in molecular biology. Here, we describe a method for the generation of ‘pHAPE’, a plasmid from which a variety of DNA ladders can be generated via simple restriction enzyme digestions. The pHAPE plasmid can be generated by mutagenesis of the commonly used pBluescript II SK+ phagemid followed by insertion of a 7141 bp sequence (comprised of three smaller, synthetic fragments). Our use of pHAPE allows us some small relief from the ever-rising costs of performing molecular biology experiments (‘Don’t worry, pHAPE’).
List of Contributors
Publisher: Elsevier
Date: 2013
Three novel Notch genes in zebrafish: implications for vertebrate Notch gene evolution and function
Publisher: Springer Science and Business Media LLC
Date: 05-1997
Abstract: Notch genes encode transmembrane receptors that interact with numerous signal transduction pathways and are essential for animal development. To facilitate analysis of vertebrate Notch gene function, we isolated cDNA fragments of three novel Notch genes from zebrafish (Danio rerio), Notch1b, Notch5 and Notch6. Notch1b is a second zebrafish Notch1 gene. From analysis of the Notch1b sequence we argue that the various vertebrate Notch gene subfamilies encode receptors with different signalling specificities. Notch5 and Notch6 represent novel vertebrate Notch gene subfamilies. Remarkably, Notch1b lacks expression in presomitic mesoderm, Notch5 is expressed in a metameric pattern within the presomitic mesoderm whilst Notch6 expression is excluded from the nervous system. The expression patterns of these genes suggest important roles in gastrulation, somitogenesis, tail bud extension, myogenesis, heart development and neurogenesis. We discuss the implications of our observations for Notch gene evolution and function.
Tyrosinase gene expression in zebrafish embryos
Publisher: Springer Science and Business Media LLC
Date: 02-04-2001
Abstract: The enzyme tyrosinase is required for the conversion of tyrosine into the pigment melanin. Thus, tyrosinase gene expression is a useful marker for studying the differentiation of melanin-expressing cells during embryogenesis. We describe the spatiotemporal pattern of transcription of the tyrosinase gene and the presence of active enzyme in whole embryos of the zebrafish, Danio rerio. At 16.5 h post-fertilisation the tyrosinase gene is transcribed in the dorsal extremity of the developing retinal pigment epithelium, approximately 7 h before visible pigmentation. Shortly thereafter, transcription in neural crest-derived melanocytes is first observed dorsolateral to the mesencephalon and diencephalon and the posterior hindbrain/anterior spinal cord. A wave of gene activation and cell migration is then observed moving towards the posterior of the animal. DOPA staining for tyrosinase activity shows the presence of active enzyme in embryos at least 3 h before visible pigmentation.
Brain transcriptomes of zebrafish and mouse Alzheimer's disease knock-in models imply early disrupted energy metabolism
Publisher: The Company of Biologists
Date: 2022
DOI: 10.1242/DMM.049187
Abstract: Energy production is the most fundamentally important cellular activity supporting all other functions, particularly in highly active organs, such as brains. Here, we summarise transcriptome analyses of young adult (pre-disease) brains from a collection of 11 early-onset familial Alzheimer's disease (EOFAD)-like and non-EOFAD-like mutations in three zebrafish genes. The one cellular activity consistently predicted as affected by only the EOFAD-like mutations is oxidative phosphorylation, which produces most of the energy of the brain. All the mutations were predicted to affect protein synthesis. We extended our analysis to knock-in mouse models of APOE alleles and found the same effect for the late onset Alzheimer's disease risk allele ε4. Our results support a common molecular basis for the initiation of the pathological processes leading to both early and late onset forms of Alzheimer's disease, and illustrate the utility of zebrafish and knock-in single EOFAD mutation models for understanding the causes of this disease.
Transcriptome analysis of a protein-truncating mutation in sortilin-related receptor 1 associated with early-onset familial Alzheimer’s disease indicates effects on mitochondrial and ribosome function in young-adult zebrafish brains
Publisher: Cold Spring Harbor Laboratory
Date: 04-09-2020
DOI: 10.1101/2020.09.03.282277
Abstract: The early cellular stresses which eventually lead to Alzheimer’s disease (AD) remain poorly understood because we cannot access living, asymptomatic human AD brains for detailed molecular analyses. Sortilin-related receptor 1 ( SORL1 ) encodes a multi-domain receptor protein genetically associated with both rare, early-onset familial AD (EOfAD) and common, sporadic late-onset AD (LOAD). SORL1 has been shown to play a role in the trafficking of the amyloid β A4 precursor protein (APP) which is cleaved proteolytically to form one of the pathological hallmarks of AD, amyloid β (Aβ) peptide. However, the other functions of SORL1 are less well understood. Here, we employed a reverse genetics approach to characterise the effect of an EOfAD mutation in SORL1 using zebrafish as a model organism. We performed targeted mutagenesis to generate an EOfAD-like mutation in the zebrafish orthologue of SORL1 , and performed RNA-sequencing on mRNA isolated from a family of fish either heterozygous for the EOfAD-like mutation or their wild type siblings and identified subtle effects on the expression of genes which likely indicate changes in mitochondrial and ribosomal function. These changes appear to be independent of changes to expression of APP-related proteins in zebrafish, and mitochondrial content.
In-Frame and Frameshift Mutations in Zebrafish Presenilin 2 Affect Different Cellular Functions in Young Adult Brains
Publisher: Cold Spring Harbor Laboratory
Date: 22-11-2021
DOI: 10.1101/2020.11.21.392761
Abstract: Mutations in PRESENILIN 2 ( PSEN2 ) cause early disease onset familial Alzheimer’s disease (EOfAD) but their mode of action remains elusive. One consistent observation for all PRESENILIN gene mutations causing EOfAD is that a transcript is produced with a reading frame terminated by the normal stop codon – the “reading frame preservation rule”. Mutations that do not obey this rule do not cause the disease. The reasons for this are debated. A frameshift mutation ( psen2 N140fs ) and a reading frame-preserving mutation ( psen2 T141_L142delinsMISLISV ) were previously isolated during genome editing directed at the N140 codon of zebrafish psen2 (equivalent to N141 of human PSEN2 ). We mated a pair of fish heterozygous for each mutation to generate a family of siblings including wild type and heterozygous mutant genotypes. Transcriptomes from young adult (6 months) brains of these genotypes were analysed. Bioinformatics techniques were used to predict cellular functions affected by heterozygosity for each mutation. The reading frame preserving mutation uniquely caused subtle, but statistically significant, changes to expression of genes involved in oxidative phosphorylation, long term potentiation and the cell cycle. The frameshift mutation uniquely affected genes involved in Notch and MAPK signalling, extracellular matrix receptor interactions and focal adhesion. Both mutations affected ribosomal protein gene expression but in opposite directions. A frameshift and frame-preserving mutation at the same position in zebrafish psen2 cause discrete effects. Changes in oxidative phosphorylation, long term potentiation and the cell cycle may promote EOfAD pathogenesis in humans.
Identification and expression analysis of the zebrafish orthologue of Klotho
Publisher: Springer Science and Business Media LLC
Date: 03-07-2011
DOI: 10.1007/S00427-011-0367-3
Abstract: Klotho is an aging suppressor gene. In mice, loss of Klotho function causes accelerated aging while increased Klotho expression increases longevity. This study aimed to identify and characterize the orthologue of Klotho in zebrafish, a powerful model organism for the investigation of development and human disease. Zebrafish klotho was identified by a bioinformatics approach, and cloning and sequencing of klotho cDNA confirmed the in silico analysis. The zebrafish Klotho protein has a structure similar to human and mouse Klotho, but it lacks an apparent secretory signal sequence. We can find no evidence of an alternative transcript isoform lacking the transmembrane domain coding sequence as seen in mammals. RT-PCR revealed the expression of klotho during embryonic development and in a wider variety of adult tissues than in mouse. Quantitative real-time RT-PCR demonstrated the relative gene expression profile of zebrafish Klotho during embryogenesis and in adult tissues. In situ hybridization showed an apparently diffuse signal of klotho mRNA expression in the adult zebrafish testis.
[P37]: A critical role for huntingtin in neural development
Publisher: Wiley
Date: 16-11-2006
Analysis of insulin-degrading enzyme (IDE) expression and function in zebrafish embryos
Publisher: Wiley
Date: 07-2012
Interference with splicing of Presenilin transcripts has potent dominant negative effects on Presenilin activity
Publisher: Oxford University Press (OUP)
Date: 02-11-2007
DOI: 10.1093/HMG/DDM317
Abstract: Missense mutations in the PRESENILIN1 (PSEN1) gene frequently underlie familial Alzheimer's disease (FAD). Nonsense and most splicing mutations result in the synthesis of truncated peptides, and it has been assumed that truncated PSEN1 protein is functionless so that heterozygotes for these mutations are unaffected. Some FAD mutations affecting PSEN1 mRNA splicing cause loss of exon 8 or 9 sequences while maintaining the reading frame. We attempted to model these exon-loss mutations in zebrafish embryos by injecting morpholino antisense oligonucleotides (morpholinos) directed against splice acceptor sites in zebrafish psen1 transcripts. However, this produced cryptic changes in splicing potentially forming mRNAs encoding truncated presenilin proteins. Aberrant splicing in the region between exons 6 and 8 produces potent dominant negative effects on Psen1 protein activity, including Notch signalling, and causes a hydrocephalus phenotype. Reductions in Psen1 activity feedback positively to increase psen1 transcription through a mechanism apparently independent of gamma-secretase. We present evidence that the dominant negative effects are mediated through production of truncated Psen1 peptides that interfere with the normal activity of both Psen1 and Psen2. Mutations causing such truncations would be dominant lethal in embryo development. Somatic cellular changes in ageing cells that interfere with PSEN1 splicing, or otherwise cause protein truncation, might contribute to sporadic Alzheimer's disease, cancer and other diseases.
Related Organisations
Council For National Academic Awards
Location: United Kingdom of Great Britain and Northern Ireland
Related Funding Activities
Discovery Projects - Grant ID: DP0773105
Start Date: 2007
End Date: 12-2011
Amount: $263,000.00
Funder: Australian Research Council
View Funded ActivityLinkage Infrastructure, Equipment And Facilities - Grant ID: LE0347607
Start Date: 2002
End Date: 12-2003
Amount: $306,000.00
Funder: Australian Research Council
View Funded ActivityResearch Networks - Grant ID: RN0457079
Start Date: 09-2004
End Date: 08-2009
Amount: $1,500,000.00
Funder: Australian Research Council
View Funded Activity