Progressive renal and vascular disease: pivotal role of the AT2 receptor

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Diabetes and renal disease are commonly associated with a range of vascular complications. I have been investigating a particular hormone system known as the renin-angiotensin system in promoting kidney and vascular complications in various diseases including diabetes. This system is a pathway which ultimately generates a hormone called angiotensin II which has many actions which could be harmful to the kidney and blood vessels. The importance of this hormone system has been demonstrated by the beneficial effects particularly on the kidney of drugs which block this pathway. It has been demonstrated that angiotensin II acts via 2 different receptors, the AT1 and AT2 subtypes. Initially the AT1 receptor was viewed to mediate most of the biological effects of angiotensin II. However, as demonstrated by our own and other groups, the AT2 receptor may play a role in mediating various effects of angiotensin II particularly in disease states. We have identified expression of this receptor in the adult kidney and in the vessel wall which may be upregulated in various disease states. The status of the AT2 receptor is not well characterised in diabetes and many other kidney diseases and this proposal will address this issue in a comprehensive manner by evaluating various sites of injury in diabetes including the kidney and vascular tree. This proporsal includes different approach to moduate this receptor involving drug blockers and animal model where this receptoris either deleted or overexpressed. These studies potentially have major implications for the management of diabetic and renal complications. It remains to be determined if the AT2 receptor confers beneficial or deleterious effects in diabetic nephropathy or other renal diseases, if these effects vary among the various organs to be studied and whether AT2 receptor antagonists may themselves be of therapeutic value in individuals at high risk of kidney and vascular disease such as people with diabetes.