Type 2 diabetes represents an escalating global health problem. In Australia 7.2% of the population has diabetes but an additional 16% have difficulty handling glucose, a problem which frequently precedes the development of diabetes. Resistance of tissues to the action of insulin is an essential pre-requisite for type 2 diabetes but is also closely associated with the syndrome of obesity, dyslipidaemia, hypertension and cardiovascular diseases (Syndrome X). Genetic factors combined with a high c ....Type 2 diabetes represents an escalating global health problem. In Australia 7.2% of the population has diabetes but an additional 16% have difficulty handling glucose, a problem which frequently precedes the development of diabetes. Resistance of tissues to the action of insulin is an essential pre-requisite for type 2 diabetes but is also closely associated with the syndrome of obesity, dyslipidaemia, hypertension and cardiovascular diseases (Syndrome X). Genetic factors combined with a high caloric intake and a sedentary lifestyle are together responsible for the development of insulin resistance. From evidence that we and others have obtained in recent years it is evident that an important mediator of insulin resistance is the amount of fat which accumulates in muscle and liver. One way in which this abnormality seems to cause insulin resistance is through interference with the normal signalling mechanism which causes increased glucose metabolism in response to insulin. While experiments in cell systems have identified some candidate molecules that may be involved, a need exists to demonstrate whether their dysregulation actually causes the insulin resistance in the whole animal or human, or are merely associated with it. We will use novel techniques to manipulate the levels of one of these candidate genes, protein kinase B-Akt, and its regulators in the muscle of rodents. We will then examine the effects of these manipulations on insulin resistance using a combination of metabolic and molecular tests. Building upon earlier work we will also determine how important different subtypes of this molecule are for both normal and abnormal insulin-glucose metabolism, and whether these molecules or others in the pathway are more important in insulin resistance. This knowledge will be invaluable in tailoring specific novel treatment strategies or drugs for prevention or treatment of insulin resistance, and thus reducing the burden of type 2 diabetes and Syndrome X.Read moreRead less
Regulation Of Insulin Signalling & Glucose Homeostasis By Protein Tyrosine Phosphatases
Funder
National Health and Medical Research Council
Funding Amount
$503,776.00
Summary
Type 2 diabetes has reached epidemic proportions afflicting roughly 6% of the adult population in Western society. Although the underlying genetic causes and the associated pathological symptoms are heterogenous, a common feature is high blood glucose due to peripheral insulin resistance. The molecular basis of insulin resistance is believed to be attributable to defects in insulin receptor (IR) signalling. The IR is a protein tyrosine kinase that phosphorylates itself and downstream substrates ....Type 2 diabetes has reached epidemic proportions afflicting roughly 6% of the adult population in Western society. Although the underlying genetic causes and the associated pathological symptoms are heterogenous, a common feature is high blood glucose due to peripheral insulin resistance. The molecular basis of insulin resistance is believed to be attributable to defects in insulin receptor (IR) signalling. The IR is a protein tyrosine kinase that phosphorylates itself and downstream substrates on tyrosine in response to insulin. Protein tyrosine phosphatases (PTPs) that dephosphorylate the IR and its substrates might be important targets for therapeutic intervention in type 2 diabetes; inhibition of specific PTPs may allow for enhanced insulin-induced signalling to alleviate insulin resistance. This proposal will examine the roles of PTPs and in particular TCPTP in IR signalling in vivo. Our studies will shed light on the molecular mechanisms of IR regulation and function and may provide important insights into novel strategies for enhancing insulin sensitivity in type 2 diabetes.Read moreRead less