Vascular smooth muscle cells (VSMC) in the healthy adult arterial wall are a highlydifferentiated cell type with low levels of proliferation. However, when activated these cells can undergo a phenotypic change to become proliferative, migratory and excrete higher levels of extra-cellular matrix. While this cellular change is an essential element of the adaptable vasculature, excessive proliferation of VSMC underpins the development of a number of disease states, including atherosclerosis and restenosis after balloon angioplasty. The activation of VSMC is dependent on intracellular signalling pathways broadly altering gene expression. A key feature of this process is the initial potent regulation of transcription factors such as Egr-1, c-Jun and Ets-1, which then drive further transcriptional changes resulting in phenotypic change. The aim of this thesis was to discover novel genes, particularly transcription factors, regulated early upon stimulation and to characterise their contribution to the activation of VSMC. A key stimulus for activation of VSMC is the release of fibroblast growth factor 2 (FGF-2). A microarray used to explore the effects of FGF-2 exposure demonstrated the extensive nature of transcriptional modulation. In addition, it highlighted a number of transcription factors that were not previously described in VSMC: p8, ATF-4 and SHARP-2. In particular, SHARP-2 was potently upregulated and was reconfirmed in animal models of vascular injury. The subsequent contribution these factors make to VSMC activation was also demonstrated. p8 strongly induced VSMC proliferation, while ATF-4 contributed to cytokine production and SHARP-2 potently downregulated VSMC differentiation markers. A second area that was explored related to a gene known as YRDC, which was found to be upregulated upon stimulation of VSMC. YRDC is highly conserved across almost all cellular life, however its function remains unknown. A number of novel splice variants of YRDC were discovered and demonstrated to be differentially regulated in VSMC upon stimulation. Further work to commence characterising its function showed that it interacts with key ribosomal proteins and most likely plays a role in regulating translation. The discovery of the relevance of these genes to vascular biology in addition to their transcriptional regulation makes an important contribution to increasing our understanding of the molecular mechanisms behind vascular remodelling.
| Identifer | oai:union.ndltd.org:ADTP/222272 |
| Date | January 2006 |
| Creators | Peden, Ryan Stephen, Medical Sciences, Faculty of Medicine, UNSW |
| Publisher | Awarded by:University of New South Wales. School of Medical Sciences |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | Copyright Ryan Stephen Peden, http://unsworks.unsw.edu.au/copyright |
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