ORCID Profile
0000-0003-1163-9902
Current Organisation
Peter MacCallum Cancer Centre
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Publisher: Elsevier BV
Date: 03-2007
Publisher: Proceedings of the National Academy of Sciences
Date: 24-07-2007
Abstract: Condensins are ubiquitously expressed multiprotein complexes that are important for chromosome condensation and epigenetic regulation of gene transcription, but whose specific roles in vertebrates are poorly understood. We describe a mouse strain, nessy, isolated during an ethylnitrosourea screen for recessive immunological mutations. The nessy mouse has a defect in T lymphocyte development that decreases circulating T cell numbers, increases their expression of the activation/memory marker CD44, and dramatically decreases the numbers of CD4 + CD8 + thymocytes and their immediate DN4 precursors. A missense mutation in an unusual alternatively spliced first exon of the kleisin β gene, a member of the condensin II complex, was shown to be responsible and act in a T cell-autonomous manner. Despite the ubiquitous expression and role of condensins, kleisin β nes/nes mice were viable, fertile, and showed no defects even in the parallel pathway of B cell lymphocyte differentiation. These data define a unique lineage-specific requirement for kleisin β in mammalian T cell differentiation.
Publisher: Public Library of Science (PLoS)
Date: 26-10-2012
Publisher: Elsevier BV
Date: 2013
DOI: 10.1016/J.JIM.2012.10.012
Abstract: Establishing CD8(+) T cell cultures has been empirical and the published methods have been largely in idual laboratory based. In this study, we optimized culturing conditions and show that IL-2 concentration is the most critical factor for the success of establishing CD8(+) T cell cultures. High IL-2 concentration encouraged T cells to non-specifically proliferate, express a B cell marker, B220, and undergo apoptosis. These cells also lose typical irregular T cell morphology and are incapable of sustaining long-term cultures. Using tetramer and intracellular cytokine assessments, we further demonstrated that many antigen-specific T cells have been rendered nonfunctional when expanded under high IL-2 concentration. When IL-2 is used in the correct range, B220-mediated cell depletion greatly enhanced the success rate of such T cell cultures.
Publisher: Springer Science and Business Media LLC
Date: 06-2007
DOI: 10.1038/NATURE05875
Abstract: Accumulation of DNA damage leading to adult stem cell exhaustion has been proposed to be a principal mechanism of ageing. Here we address this question by taking advantage of the highly specific role of DNA ligase IV in the repair of DNA double-strand breaks by non-homologous end-joining, and by the discovery of a unique mouse strain with a hypomorphic Lig4(Y288C) mutation. The Lig4(Y288C) mouse, identified by means of a mutagenesis screening programme, is a mouse model for human LIG4 syndrome, showing immunodeficiency and growth retardation. Diminished DNA double-strand break repair in the Lig4(Y288C) strain causes a progressive loss of haematopoietic stem cells and bone marrow cellularity during ageing, and severely impairs stem cell function in tissue culture and transplantation. The sensitivity of haematopoietic stem cells to non-homologous end-joining deficiency is therefore a key determinant of their ability to maintain themselves against physiological stress over time and to withstand culture and transplantation.
Publisher: Elsevier BV
Date: 12-2007
Publisher: Proceedings of the National Academy of Sciences
Date: 29-03-2010
Abstract: MHC class I molecules function to display peptides generated from cellular and pathogen gene products for immune surveillance by CD8 + T cells. Cells typically express ∼100,000 class I molecules, or ∼1 per 30,000 cellular proteins. Given “one protein, one peptide” representation, immunosurveillance would be heavily biased toward the most abundant cell proteins. Cells use several mechanisms to prevent this, including the predominant use of defective ribosomal products (DRiPs) to generate peptides from nascent proteins and, as we show here, compartmentalization of DRiP peptide generation to prevent competition from abundant cytosolic peptides. This provides an explanation for the exquisite ability of T cells to recognize peptides generated from otherwise undetected gene products.
Publisher: Rockefeller University Press
Date: 09-04-2007
DOI: 10.1084/JEM.20061923
Abstract: Immunological memory is characterized by heightened immunoglobulin (Ig) G antibody production caused in part by enhanced plasma cell formation conferred by conserved transmembrane and cytoplasmic segments in isotype-switched IgG B cell receptors. We tested the hypothesis that the IgG tail enhances intracellular B cell antigen receptor (BCR) signaling responses to antigen by analyzing B cells from Ig transgenic mice with IgM receptors or chimeric IgMG receptors containing the IgG tail segment. The IgG tail segment enhanced intracellular calcium responses but not tyrosine or extracellular signal–related kinase (ERK) phosphorylation. Biochemical analysis and crosses to CD22-deficient mice established that IgG tail enhancement of calcium and antibody responses, as well as marginal zone B cell formation, was not due to diminished CD22 phosphorylation or inhibitory function. Microarray profiling showed no evidence for enhanced signaling by the IgG tail for calcium/calcineurin, ERK, or nuclear factor κB response genes and little evidence for any enhanced gene induction. Instead, almost half of the antigen-induced gene response in IgM B cells was diminished 50–90% by the IgG tail segment. These findings suggest a novel “less-is-more” hypothesis to explain how switching to IgG enhances B cell memory responses, whereby decreased BCR signaling to genes that oppose marginal zone and plasma cell differentiation enhances the formation of these key cell types.
Publisher: Wiley
Date: 06-01-2015
DOI: 10.1038/ICB.2014.113
Abstract: T-cell repertoire is selected according to self peptide-MHC (major histocompatibility complex) complexes in the thymus. Although most peripheral T cells recognize specific pathogen-derived peptides complexed to self-MHC exclusively, some possess cross-reactivity to other self or foreign peptides presented by self-MHC molecules a phenomenon often termed T-cell receptor (TCR) promiscuity or degeneracy. TCR promiscuity has been attributed to various autoimmune conditions. On the other hand, it is considered a mechanism for a relatively limited TCR repertoire to deal with a potentially much larger antigenic peptide repertoire. Such property has also been utilized to bypass self-tolerance for cancer vaccine development. Although many studies explored such degeneracy for peptide of the same length, few studies reported such properties for peptides of different length. In this study, we finely characterized the CD8(+) T-cell response specific for a 11mer peptide derived from influenza A viral polymerase basic protein 2. The short-term T-cell line, despite possessing highly biased TCR, was able to react with multiple peptides of different length sharing the same core sequence. Out data clearly showed the importance of detailed and quantitative assessments for such T-cell specificity. Our data also emphasize the importance of biochemical demonstration of the naturally presented minimal peptide.
Publisher: Wiley
Date: 12-2014
Abstract: Vertebrates have evolved to express major histocompatibility complexes (MHCs) that present peptides of the intra-cellular proteome for immunosurveillance against viruses and tumor. The MHC class I (MHC-I) processing and presentation pathway allows for scrutiny of all cellular proteins and peptides by CD8(+) cytotoxic T cells. The proteasome is part of the specialised machinery that degrades proteins down to peptides with the correct sequence for MHC-I binding. However, much conjecture lies as to how the various proteasome isoforms and their active subunits create antigenic peptides, and if the specialised immunoproteasome solely performs this job. In this issue of the European Journal of Immunology, Mishto et al. [Eur. J. Immunol. 2014. 44: 3508-3521] address this question through systematic biochemical peptide degradation studies and provide new insights into the functions of proteasome β-subunits.
Publisher: The American Association of Immunologists
Date: 11-2007
Publisher: Public Library of Science (PLoS)
Date: 04-06-2013
Publisher: Springer Science and Business Media LLC
Date: 24-06-2021
DOI: 10.1038/S41467-021-24273-8
Abstract: The concept that extracellular vesicles (EVs) from the diet can be absorbed by the intestinal tract of the consuming organism, be bioavailable in various organs, and in-turn exert phenotypic changes is highly debatable. Here, we isolate EVs from both raw and commercial bovine milk and characterize them by electron microscopy, nanoparticle tracking analysis, western blotting, quantitative proteomics and small RNA sequencing analysis. Orally administered bovine milk-derived EVs survive the harsh degrading conditions of the gut, in mice, and is subsequently detected in multiple organs. Milk-derived EVs orally administered to mice implanted with colorectal and breast cancer cells reduce the primary tumor burden. Intriguingly, despite the reduction in primary tumor growth, milk-derived EVs accelerate metastasis in breast and pancreatic cancer mouse models. Proteomic and biochemical analysis reveal the induction of senescence and epithelial-to-mesenchymal transition in cancer cells upon treatment with milk-derived EVs. Timing of EV administration is critical as oral administration after resection of the primary tumor reverses the pro-metastatic effects of milk-derived EVs in breast cancer models. Taken together, our study provides context-based and opposing roles of milk-derived EVs as metastasis inducers and suppressors.
Publisher: Springer Science and Business Media LLC
Date: 2007
Publisher: Public Library of Science (PLoS)
Date: 2007
Publisher: Elsevier BV
Date: 04-2006
DOI: 10.1016/J.BBRC.2006.02.032
Abstract: The biochemical differences between simple steatosis, a benign liver disease, and non-alcoholic steatohepatitis, which leads to cirrhosis, are unclear. Fat aussie is an obese mouse strain with a truncating mutation (foz) in the Alms1 gene. Chow-fed female foz/foz mice develop obesity, diabetes, and simple steatosis. We fed foz/foz and wildtype mice a high-fat diet. Foz/foz mice developed serum ALT elevation and severe steatohepatitis with hepatocyte ballooning, inflammation, and fibrosis wildtype mice showed simple steatosis. Biochemical pathways favoring hepatocellular lipid accumulation (fatty acid uptake lipogenesis) and lipid disposal (fatty acid beta-oxidation triglyceride egress) were both induced by high-fat feeding in wildtype but not foz/foz mice. The resulting extremely high hepatic triglyceride levels were associated with induction of mitochondrial uncoupling protein-2 and adipocyte-specific fatty acid binding protein-2, but not cytochrome P4502e1 or lipid peroxidation. In this model of metabolic syndrome, transition of steatosis to steatohepatitis was associated with hypoadiponectinemia, a mediator of hepatic fatty acid disposal pathways.
Publisher: American Society of Hematology
Date: 03-2008
DOI: 10.1182/BLOOD-2007-03-080994
Abstract: Activin-A is a transforming growth factor-β (TGF-β) superfamily member that plays a pivotal role in many developmental and reproductive processes. It is also involved in neuroprotection, apoptosis of tumor and some immune cells, wound healing, and cancer. Its role as an immune-regulating protein has not previously been described. Here we demonstrate for the first time that activin-A has potent autocrine effects on the capacity of human dendritic cells (DCs) to stimulate immune responses. Human monocyte-derived DCs (MoDCs) and the CD1c+ and CD123+ peripheral blood DC populations express both activin-A and the type I and II activin receptors. Furthermore, MoDCs and CD1c+ myeloid DCs rapidly secrete high levels of activin-A after exposure to bacteria, specific toll-like receptor (TLR) ligands, or CD40 ligand (CD40L). Blocking autocrine activin-A signaling in DCs using its antagonist, follistatin, enhanced DC cytokine (IL-6, IL-10, IL-12p70, and tumor necrosis factor-α [TNF-α]) and chemokine (IL-8, IP-10, RANTES, and MCP-1) production during CD40L stimulation, but not TLR-4 ligation. Moreover, antagonizing DC-derived activin-A resulted in significantly enhanced expansion of viral antigen-specific effector CD8+ T cells. These findings establish an immune-regulatory role for activin-A in DCs, highlighting the potential of antagonizing activin-A signaling in vivo to enhance vaccine immunogenicity.
Publisher: Wiley
Date: 05-12-2013
Abstract: CD4(+) CD25(+) FoxP3(+) naturally occurring regulatory T (Treg) cells play a crucial role in the maintenance of immune tolerance and in preventing autoimmune pathology. Interventions that expand Treg cells are highly desirable, as they may offer novel treatment options in a variety of autoimmune and transplantation settings. Paralleling previous preclinical studies, we demonstrate here that administration of the hematopoietic growth factor Flt3L to human subjects increases the frequency and absolute number of Treg cells, and reduces the ratio of CD8(+) T cells to Treg cells in the peripheral blood. The increase in Treg cells was due to enhanced Treg-cell proliferation rather than release of Treg cells from the thymus. Further studies revealed that Flt3L-induced proliferation of Treg cells was an indirect effect that occurred via the interaction of Treg cells with the Flt3L-expanded pool of CD1c(+) myeloid dendritic cells. On the basis of these findings, Flt3L may represent a promising agent for promoting immune tolerance in a variety of clinical settings.
Publisher: The American Association of Immunologists
Date: 07-2013
Abstract: The three proteasome subunits with proteolytic activity are encoded by standard or immunoproteasome genes. Many proteasomes expressed by normal cells and cells exposed to cytokines are “mixed”, that is, contain both standard and immunoproteasome subunits. Using a panel of 38 defined influenza A virus–derived epitopes recognized by C57BL/6 mouse CD8+ T cells, we used mice with targeted disruption of β1i, β2i, or β5i/β2i genes to examine the contribution of mixed proteasomes to the immunodominance hierarchy of antiviral CD8+ T cells. We show that each immunoproteasome subunit has large effects on the primary and recall immunodominance hierarchies due to modulating both the available T cell repertoire and generation of in idual epitopes as determined both biochemically and kinetically in Ag presentation assays. These findings indicate that mixed proteasomes function to enhance the ersity of peptides and support a broad CD8+ T cell response.
Publisher: Elsevier BV
Date: 06-2008
Publisher: Elsevier BV
Date: 2012
Publisher: The American Association of Immunologists
Date: 15-05-2017
Abstract: CD8+ T cell immunosurveillance is based on recognizing oligopeptides presented by MHC class I molecules. Despite decades of study, the importance of protein ubiquitylation to peptide generation remains uncertain. In this study, we examined the ability of MLN7243, a recently described ubiquitin-activating enzyme E1 inhibitor, to block overall cytosolic peptide generation and generation of specific peptides from vaccinia- and influenza A virus–encoded proteins. We show that MLN7243 rapidly inhibits ubiquitylation in a variety of cell lines and can profoundly reduce the generation of cytosolic peptides. Kinetic analysis of specific peptide generation reveals that ubiquitylation of defective ribosomal products is rate limiting in generating class I peptide complexes. More generally, our findings demonstrate that the requirement for ubiquitylation in MHC class I–restricted Ag processing varies with class I allomorph, cell type, source protein, and peptide context. Thus, ubiquitin-dependent and -independent pathways robustly contribute to MHC class I–based immunosurveillance.
Publisher: Proceedings of the National Academy of Sciences
Date: 11-05-2011
Abstract: Immunodominant T-cell responses are important for virus clearance. However, the identification of immunodominant T-cell peptide + HLA glycoprotein epitopes has been hindered by the extent of HLA polymorphism and the limitations of predictive algorithms. A simple, systematic approach has been used here to screen for immunodominant CD8 + T-cell specificities. The analysis targeted healthy HLA-A2 + donors to allow comparison with responses to the well-studied influenza matrix protein 1 epitope. Although influenza matrix protein 1 was consistently detected in all in idual s les in our study, the response to this epitope was only immunodominant in three of eight, whereas for the other five, prominent CD8 + T-cell responses tended to focus on various peptides from the influenza nucleoprotein that were not presented by HLA-A2. Importantly, with the four immunodominant T-cell epitopes identified here, only one would have been detected by the current prediction programs. The other three peptides would have been either considered too long or classified as not containing typical HLA binding motifs. Our data stress the importance of systematic analysis for discovering HLA-dependent, immunodominant CD8 + T-cell epitopes derived from viruses and tumors. Focusing on HLA-A2 and predictive algorithms may be too limiting as we seek to develop targeted immunotherapy and vaccine strategies that depend on T cell-mediated immunity.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 16-06-2006
Publisher: Springer Science and Business Media LLC
Date: 15-01-2021
Publisher: Springer Science and Business Media LLC
Date: 08-11-2007
DOI: 10.1038/NATURE06253
Abstract: Immune responses are normally targeted against microbial pathogens and not self-antigens by mechanisms that are only partly understood. Here we define a newly discovered pathway that prevents autoimmunity by limiting the levels on T lymphocytes of aco-stimulatory receptor, the inducible T-cell co-stimulator(ICOS). In sanroque mice homozygous for an M199R mutation in the ROQ domain of Roquin (also known as Rc3h1), increased Icos expression on T cells causes the accumulation of lymphocytes that is associated with a lupus-like autoimmune syndrome. Roquin normally limits Icos expression by promoting the degradation of Icos messenger RNA.A conserved segment in the unusually long ICOS 3' untranslated mRNA is essential for regulation by Roquin. This segment comprises a 47-base-pair minimal region complementary to T-cell-expressed microRNAs including miR-101, the repressive activity of which is disrupted by base-pair inversions predicted to abrogate miR-101 binding. These findings illuminate a critical post-transcriptional pathway within T cells that regulates lymphocyte accumulation and autoimmunity, and highlights the therapeutic potential of partially antagonising the ICOS pathway.
Publisher: Wiley
Date: 20-03-2007
Abstract: Genetic variants of interleukin 2 (IL-2) and its receptor are associated with murine and human susceptibility to Type 1 diabetes, yet the role of IL-2 in controlling pancreatic islet-reactive T cells is unknown. Here, we develop a model where IL-2 deficiency precipitates a breakdown of self-tolerance and progression to diabetes, and its action upon diabetogenic islet-specific CD4 T cells can be tracked. We find that IL-2 is not required for Aire-dependent thymic clonal deletion of high-avidity diabetogenic clones, but is essential for thymic formation of islet-specific Foxp3-expressing CD4 T cells. The absence of IL-2 results in the expansion of low-avidity Foxp3(-) islet-reactive CD4 T cells. The mechanism by which IL-2 prevents diabetes is therefore through the establishment of a repertoire of islet-reactive Foxp3(+) T cells within the thymus, and limitation of the peripheral activation of low-avidity islet-reactive T cells that normally escape thymic negative selection.
Publisher: Informa UK Limited
Date: 02-04-2015
Publisher: American Society of Hematology
Date: 12-2006
DOI: 10.1182/BLOOD-2006-02-004531
Abstract: Despite the importance of thymic stromal cells to T-cell development, relatively little is known about their biology. Here, we use single-cell analysis of stromal cells to analyze extensive changes in the number and composition of thymic stroma throughout life, revealing a surprisingly dynamic population. Phenotypic progression of thymic epithelial subsets was assessed at high resolution in young mice to provide a developmental framework. The cellular and molecular requirements of adult epithelium were studied, using various mutant mice to demonstrate new cross talk checkpoints dependent on RelB in the cortex and CD40 in the medulla. With the use of Ki67 and BrdU labeling, the turnover of thymic epithelium was found to be rapid, but then diminished on thymic involution. The various defects in stromal turnover and composition that accompanied involution were rapidly reversed following sex steroid ablation. Unexpectedly, mature cortical and medullary epithelium showed a potent capacity to stimulate naive T cells, comparable to that of thymic dendritic cells. Overall, these studies show that the thymic stroma is a surprisingly dynamic population and may have a more direct role in negative selection than previously thought.
Publisher: Springer US
Date: 2007
Publisher: American Society for Microbiology
Date: 15-10-2014
DOI: 10.1128/JVI.01631-14
Abstract: Antigen-specific CD4 + T cells are essential for effective virus-specific host responses, with recent human challenge studies (in volunteers) establishing their importance for influenza A virus (IAV)-specific immunity. However, while many IAV CD4 + T cell epitopes have been identified, few are known to stimulate immunodominant CD4 + T cell responses. Moreover, much remains unclear concerning the major antigen(s) responded to by the human CD4 + T cells and the extents and magnitudes of these responses. We initiated a systematic screen of immunodominant CD4 + T cell responses to IAV in healthy in iduals. Using in vitro expanded-multispecificity IAV-specific T cell lines and in idual IAV protein antigens produced by recombinant vaccinia viruses, we found that the internal matrix protein 1 (M1) and nucleoprotein (NP) were the immunodominant targets of CD4 + T cell responses. Ten epitopes derived from M1 and NP were definitively characterized. Furthermore, epitope sequence conservation analysis established that immunodominance correlated with an increased frequency of mutations, reflecting the fact that these prominent epitopes are under greater selective pressure. Such evidence that particular CD4 + T cells are important for protection/recovery is of value for the development of novel IAV vaccines and for our understanding of different profiles of susceptibility to these major pathogens. IMPORTANCE Influenza virus causes half a million deaths annually. CD4 + T cell responses have been shown to be important for protection against influenza and for recovery. CD4 + T cell responses are also critical for efficient CD8 + T cell response and antibody response. As immunodominant T cells generally play a more important role, characterizing these immunodominant responses is critical for influenza vaccine development. We show here that the internal matrix protein 1 (M1) and nucleoprotein (NP), rather than the surface proteins reported previously, are the immunodominant targets of CD4 + T cell responses. Interestingly, these immunodominant epitope regions accumulated many mutations over time, which likely indicates increased immune pressure. These findings have significant implications for the design of T cell-based influenza vaccines.
Publisher: The American Association of Immunologists
Date: 15-10-2006
DOI: 10.4049/JIMMUNOL.177.8.5155
Abstract: Coligation of CD21 with BCR on the surface of B cells provides a costimulatory signal essential for efficient Ab responses to T-dependent Ags. To achieve this, Ag must be directly linked to C3 fragments, but how this occurs in vivo is not fully understood. Using BCR transgenic mice, we demonstrated that C3 was deposited on the surface of B cells following both high- and moderate-affinity Ag binding. This was dependent on the specific binding of IgM to the BCR-bound Ag and can occur independently of soluble immune complex formation. Based on these data, we propose a novel model in which immune complexes can form directly on the surface of the B cell following Ag binding. This model has implications for our understanding of B lymphocyte activation.
Publisher: Elsevier BV
Date: 07-2007
DOI: 10.1016/J.CELL.2007.06.033
Abstract: In the immune system, many tolerance checkpoints exist to prevent self-antigens from stimulating the relentless growth of self-reactive B and T lymphocytes. The genes and molecular pathways underpinning these checkpoints overlap with those involved in tumor suppression. As with an inherited predisposition to cancer, inherited defects in self-tolerance genes typically precipitate autoimmune disease stochastically after a latent phase. Multiple mutations, inherited and somatic, may be needed before a self-reactive clone bypasses sequential tolerance checkpoints resulting in the emergence of autoimmune disease.
Publisher: Wiley
Date: 03-03-2015
Abstract: Differentiation of CD8(+) T lymphocytes into effector and memory cells is key for an adequate immune response and relies on complex interplay of pathways that convey signals from the cell surface to the nucleus. In this study, we investigated the proteome of four cytotoxic T-cell subtypes naïve, recently activated effector, effector, and memory cells. Cells were fractionated into membrane, cytosol, soluble nuclear, chromatin-bound, and cytoskeletal compartments. Following LC-MS/MS analysis, identified peptides were analyzed via MaxQuant. Compartment fractionation and gel-LC-MS separation resulted in 2399 proteins identified in total. Comparison between the different subsets resulted in 146 significantly regulated proteins for naïve and effector cells, followed by 116 for activated, and 55 for memory cells. Besides Granzyme B signaling (for activated and/ or effector cells vs. naïve cells), the most prominent changes occurred in the TCA cycle and aspartate degradation. These changes suggest that correct balancing of metabolism is key for differentiation processes. All MS data have been deposited in the ProteomeXchange with identifier PXD001065 (ataset/PXD001065).
Publisher: The American Association of Immunologists
Date: 15-04-2010
Abstract: Proteasomes are multisubunit proteases that initiate degradation of many Ags presented by MHC class I molecules. Vertebrates express alternate forms of each of the three catalytic proteasome subunits: standard subunits, and immunosubunits, which are constitutively expressed by APCs and are induced in other cell types by exposure to cytokines. The assembly of mixed proteasomes containing standard subunits and immunosubunits is regulated in a tissue specific manner. In this study, we report that the presence of mixed proteasomes in immune cells in LMP2−/− mice compromises multiple components that contribute to the generation of antiviral Ab responses, including splenic B cell numbers, survival and function of adoptively transferred B cells, Th cell function, and dendritic cell secretion of IL-6, TNF-α, IL-1β, and type I IFNs. These defects did not result from compromised overall protein degradation, rather they were associated with altered NF-κB activity. These findings demonstrate an important role for immunoproteasomes in immune cell function beyond their contribution to Ag processing.
Location: Australia
No related grants have been discovered for Damien Zanker.