A New Paradigm For SWI/SNF Chromatin Function; The ATPase Dependent Remodeler Is A Component Of The MeCP2 Complex
Funder
National Health and Medical Research Council
Funding Amount
$254,250.00
Summary
DNA methylation is a major determinant in the epigenetic silencing of many genes. The mechanisms underlying that targeting of DNA methylation and the consequence, that is, transcriptional silencing are relevant to human development and disease. Examples of the significance of alterations in the controls of DNA methylation and histone deacetylation in human disease include mental retardation (fragile X syndrome, Rett syndrome) and carcinogenesis. Evidence is emerging that a family of methylation ....DNA methylation is a major determinant in the epigenetic silencing of many genes. The mechanisms underlying that targeting of DNA methylation and the consequence, that is, transcriptional silencing are relevant to human development and disease. Examples of the significance of alterations in the controls of DNA methylation and histone deacetylation in human disease include mental retardation (fragile X syndrome, Rett syndrome) and carcinogenesis. Evidence is emerging that a family of methylation specific (methyl-CpG binding domain, MBD) proteins have the capacity to bind to methylated sequences and repress transcription. The mechanisms that target CpG methylation however still remain unclear. Furthermore, it is becoming increasingly evident that methyl-CpG binding proteins are not alone in silencing transcription and other epigenetic components are thought to influence transcription (namely, SWI-SNF activation complex). This grant proposal concentrates on our most recent work which demonstrates a new molecular mechanism of transcriptional repression extending the mechanism mediated by MeCP2. Our results are the first to show that the human SWI-SNF ATPase complex is a transcriptional repressor and is identified as part of the MeCP2-histone deacetylase repressor complex. This data extends the mechanistic link between DNA methylation, chromatin remodelling and transcriptional regulation. More importantly, the experimental findings could lead to a re-examination of the mechanistic basis behind MeCP2 transcriptional repression and epigenetic modification. Our findings suggest a new paradigm for SWI-SNF as a component of the MeCP2 methylation dependent silencing complex.Read moreRead less
Myoendothelial Gap Junctions: Their Composition And Role In Vasodilator Responses Attributed To EDHF
Funder
National Health and Medical Research Council
Funding Amount
$282,750.00
Summary
Cardiovascular disease, including coronary heart disease and stroke, continues to be the major cause of death in Australia and hypertension is a significant risk factor. The endothelium, which lines blood vessels of all sizes, is critical to the control of blood flow to the organs of the body. Endothelial cells release factors which can cause blood vessels to constrict or to relax, thus decreasing or increasing blood flow, respectively. Under normal conditions, the endothelium is more important ....Cardiovascular disease, including coronary heart disease and stroke, continues to be the major cause of death in Australia and hypertension is a significant risk factor. The endothelium, which lines blood vessels of all sizes, is critical to the control of blood flow to the organs of the body. Endothelial cells release factors which can cause blood vessels to constrict or to relax, thus decreasing or increasing blood flow, respectively. Under normal conditions, the endothelium is more important as a source of relaxing factors, while under hypertensive conditions, the balance is shifted in favour of the release of constricting factors. Thus, restoration of the vasodilatory function of the endothelium is seen as an important new therapeutic target in the treatment of vascular disorders. Present data suggests that the action of one of the major endothelial derived vasodilatory factors, the so-called endothelium-derived hyperpolarizing factor, EDHF, requires the presence of particular structures within the vascular wall, but little is known about the molecules of which they are comprised. We have identified two unique situations, during development and during hypertension, when these structures are present in vessels in which they are absent in normal adults. We will use gene microarrays to identify the specific molecules involved in these structures and use physiological studies to test the role of these proteins and structures in vasodilatory responses. The results of these studies may identify new targets for therapeutic intervention to restore the action of EDHF in hypertension.Read moreRead less
Early Events In Arteriolar Remodeling: Adaptation To Prolonged Vasoconstriction
Funder
National Health and Medical Research Council
Funding Amount
$415,750.00
Summary
Small arteries, while acutely responding to their environment with changes in diameter to regulate local blood flow and pressure, also undergo structural adaptation or remodelling. These events occur over a range of time-frames and involve both non-genetically and genetically regulated events. Thus a contractile event, while initially decreasing vessel diameter, also activates longer time frame processes which can span from rearrangment of cellular junctions-contacts to overt structural changes ....Small arteries, while acutely responding to their environment with changes in diameter to regulate local blood flow and pressure, also undergo structural adaptation or remodelling. These events occur over a range of time-frames and involve both non-genetically and genetically regulated events. Thus a contractile event, while initially decreasing vessel diameter, also activates longer time frame processes which can span from rearrangment of cellular junctions-contacts to overt structural changes within the vessel wall (for example thickening of the muscle layer). These adaptive processes may enable the forces of contraction to be maintained without continued energy expenditure and damage to the vessel per se. However, they can also contribute to long-term alterations in the control of blood pressure and perhaps contribute to states of hypertension as well as other common vascular diseases. For these studies we will use arterioles, isolated by microsurgical techniques, together with sophisticated computer and video-based approaches. These techniques allow arterioles to be studied under controlled conditions and relevant biochemical measurements performed. We will also use a cell model where cultured cells will be studied after defined periods of mechanical stimulation (for example stretch). Cells will be probed using a novel microscopic technique (atomic force microscopy) which enables the cell membrane to be studied with respect to changes in composition as well as physical characteristics (for example stiffness). The studies are relevant to our understanding of the normal adaptive processes occurring within blood vessels to control blood flow and pressure. The studies are also of direct relevance to our understanding of common vascular disease states including hypertension, complications of diabetes and chronic inflammatory disorders.Read moreRead less
Essential Roles Of RNA Polymerase II Transcription And DNA Damage Response Pathway In The Maintenance Of Centromere Chromatin Assembly
Funder
National Health and Medical Research Council
Funding Amount
$601,224.00
Summary
A centromere is a region of DNA typically found near the middle of a chromosome where two identical sister chromatids come in contact. It is involved in cell division as the point of attachment to the mitotic spindle. Defective centromeres can result in genome instability, infertility and development of cancers. This work involves a study into how the identity of a centromere is maintained and inherited after each cell division. This has significant implication in the understanding of cell growt ....A centromere is a region of DNA typically found near the middle of a chromosome where two identical sister chromatids come in contact. It is involved in cell division as the point of attachment to the mitotic spindle. Defective centromeres can result in genome instability, infertility and development of cancers. This work involves a study into how the identity of a centromere is maintained and inherited after each cell division. This has significant implication in the understanding of cell growth and cancer development.Read moreRead less
Epigenetic Regulation Of Telomere Chromatin And Genome Stability
Funder
National Health and Medical Research Council
Funding Amount
$633,447.00
Summary
Telomeres are structures at the end of the chromosomes that impact cell replication. 15% of cancers, called ALT cancers, show telomere instability, increased DNA damage and are frequently mutated for the ATRX gene. ALT cancers have poor prognosis, due to the limited understanding of ALT cancer activation. This study aims to create a model of ALT activation to uncover the mechanisms that control ALT tumourigenesis. This could lead to potential ALT-specific diagnostic and therapeutic tools.