ORCID Profile
0000-0001-7532-1747
Current Organisation
Monash University
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Publisher: The Company of Biologists
Date: 2020
DOI: 10.1242/DMM.042218
Abstract: Cleft lip and palate are common birth defects resulting from failure of the facial processes to fuse during development. The mammalian grainyhead-like (Grhl1-3) genes play key roles in a number of tissue fusion processes including neurulation, epidermal wound healing and eyelid fusion. One family member, Grhl2, is expressed in the epithelial lining of the first pharyngeal arch in mice at embryonic day (E) 10.5, prompting analysis of the role of this factor in palatogenesis. Grhl2-null mice die at E11.5 with neural tube defects and a cleft face phenotype, precluding analysis of palatal fusion at later stage of development. However, the first pharyngeal arch of Grhl2 null embryos manifests dysregulation of transcription factors that drive epithelial-mesenchymal transition (EMT). The aberrant expression of these genes is associated with a shift in RNA splicing patterns that favours generation of mesenchymal isoforms of numerous regulators. Driving the EMT perturbation is loss of expression of the EMT-suppressing transcription factors Ovol1 and Ovol2, which are direct GRHL2 targets. The expression of the miR-200 family of microRNAs, also GRHL2 targets, is similarly reduced, resulting in a 56-fold upregulation of Zeb1 expression, a major driver of mesenchymal cellular identity. The critical role of GRHL2 in mediating cleft palate in Zeb1−/− mice is evident, with rescue of both palatal and facial fusion seen in Grhl2−/− Zeb1−/− embryos. These findings highlight the delicate balance between GRHL2/ZEB1 and epithelial/mesenchymal cellular identity that is essential for normal closure of the palate and face. Perturbation of this pathway may underlie cleft palate in some patients.
Publisher: Elsevier BV
Date: 12-2016
Publisher: Public Library of Science (PLoS)
Date: 09-12-2019
Publisher: Rockefeller University Press
Date: 09-08-2016
DOI: 10.1084/JEM.20161903
Abstract: In the thymus, hematopoietic progenitors commit to the T cell lineage and undergo sequential differentiation to generate erse T cell subsets, including major histocompatibility complex (MHC)–restricted αβ T cell receptor (TCR) T cells and non–MHC-restricted γδ TCR T cells. The factors controlling precursor commitment and their subsequent maturation and specification into αβ TCR versus γδ TCR T cells remain unclear. Here, we show that the tyrosine phosphatase PTPN2 attenuates STAT5 (signal transducer and activator of transcription 5) signaling to regulate T cell lineage commitment and SRC family kinase LCK and STAT5 signaling to regulate αβ TCR versus γδ TCR T cell development. Our findings identify PTPN2 as an important regulator of critical checkpoints that dictate the commitment of multipotent precursors to the T cell lineage and their subsequent maturation into αβ TCR or γδ TCR T cells.
Publisher: Elsevier BV
Date: 02-2010
Publisher: Wiley
Date: 12-04-2021
DOI: 10.1111/VDE.12956
Abstract: There has been selective pressure to maintain a skin barrier since terrestrial animals evolved 360 million years ago. These animals acquired an unique integumentary system with a keratinized, stratified, squamous epithelium surface barrier. The barrier protects against dehydration and entry of microbes and toxins. The skin barrier centres on the stratum corneum layer of the epidermis and consists of cornified envelopes cemented by the intercorneocyte lipid matrix. Multiple components of the barrier undergo cross‐linking by transglutaminase (TGM) enzymes, while keratins provide additional mechanical strength. Cellular tight junctions also are crucial for barrier integrity. The grainyhead‐like (GRHL) transcription factors regulate the formation and maintenance of the integument in erse species. GRHL3 is essential for formation of the skin barrier during embryonic development, whereas GRHL1 maintains the skin barrier postnatally. This is achieved by transactivation of Tgm1 and Tgm5 , respectively. In addition to its barrier function, GRHL3 plays key roles in wound repair and as an epidermal tumour suppressor. In its former role, GRHL3 activates the planar cell polarity signalling pathway to mediate wound healing by providing directional migration cues. In squamous epithelium, GRHL3 regulates the balance between proliferation and differentiation, and its loss induces squamous cell carcinoma (SCC). In the skin, this is mediated through increased expression of MIR21 , which reduces the expression levels of GRHL3 and its direct target, PTEN , leading to activation of the PI3K‐AKT signalling pathway. These data position the GRHL family as master regulators of epidermal homeostasis across a vast gulf of evolutionary history.
Publisher: Portland Press Ltd.
Date: 27-09-2016
DOI: 10.1042/BCJ20160571
Abstract: Mutations in myosin VI have been associated with autosomal-recessive (DFNB37) and autosomal-dominant (DFNA22) deafness in humans. Here, we characterise an myosin VI nonsense mutation (R1166X) that was identified in a family with hereditary hearing loss in Pakistan. This mutation leads to the deletion of the C-terminal 120 amino acids of the myosin VI cargo-binding domain, which includes the WWY-binding motif for the adaptor proteins LMTK2, Tom1 as well as Dab2. Interestingly, compromising myosin VI vesicle-binding ability by expressing myosin VI with the R1166X mutation or with single point mutations in the adaptor-binding sites leads to increased F-actin binding of this myosin in vitro and in vivo. As our results highlight the importance of cargo attachment for regulating actin binding to the motor domain, we perform a detailed characterisation of adaptor protein binding and identify single amino acids within myosin VI required for binding to cargo adaptors. We not only show that the adaptor proteins can directly interact with the cargo-binding tail of myosin VI, but our in vitro studies also suggest that multiple adaptor proteins can bind simultaneously to non-overlapping sites in the myosin VI tail. In conclusion, our characterisation of the human myosin VI deafness mutant (R1166X) suggests that defects in cargo binding may leave myosin VI in a primed/activated state with an increased actin-binding ability.
Publisher: Elsevier BV
Date: 11-2018
Location: Pakistan
Start Date: 2009
End Date: 2009
Funder: British Council
View Funded ActivityStart Date: 2010
End Date: 2012
Funder: Higher Education Commission, Pakistan
View Funded Activity