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
Hepatic Oxidative Stress, PTPs & STAT Signalling In Obesity
Funder
National Health and Medical Research Council
Funding Amount
$1,086,547.00
Summary
Obesity is increasing at an alarming rate worldwide and is a leading cause of morbidity and mortality. Obesity is causally linked to the development of insulin resistance, a prelude to type 2 diabetes. In this proposal we will define a novel liver centric mechanism by which insulin resistance and oxidative stress may promote the development of morbid obesity, type 2 diabetes and liver disease.
Regulation Of Hypothalamic Insulin & Leptin Signalling By TCPTP
Funder
National Health and Medical Research Council
Funding Amount
$758,504.00
Summary
Insulin & leptin signal in the brain to lower blood glucose, suppress food intake, increase activity & increase energy expenditure. Obesity diminishes the abilities of insulin & leptin to signal. This proposal will determine if the enzyme TCPTP terminates insulin & leptin signaling in the brain. Our studies will provide insight into the molecular causes of obesity & may identify a novel therapeutic target for the treatment of obesity & type 2 diabetes.
Regulation Of Insulin Sensitivity By Reactive Oxygen Species
Funder
National Health and Medical Research Council
Funding Amount
$564,644.00
Summary
In morbid obesity and type 2 diabetes chronic levels of reactive oxygen species (ROS) are detrimental and diminish insulin's ability to maintain normal blood glucose levels. Paradoxically, ROS also promote insulin action by inhibiting enzymes known as protein tyrosine phosphatases (PTPs). This proposal will determine whether the promotion of ROS for the inhibition of PTPs early in the progression of type 2 diabetes may be of therapeutic benefit.
Validating A New Model For Growth Hormone Receptor Activation
Funder
National Health and Medical Research Council
Funding Amount
$472,500.00
Summary
Growth hormone is an important hormone therapeutic for treating dwarfism. Recently, many new therapeutic applications for growth hormone have been discovered, particularly in relation to its anabolic actions. These include post surgery recovery, enhanced bone fracture healing, Crohns disease, dilated cardiomyopathy, infertility and ageing. The hormone exerts these actions through its receptor, which is a class1 cytokine receptor, similar to many receptors important in regulating immunity, inflam ....Growth hormone is an important hormone therapeutic for treating dwarfism. Recently, many new therapeutic applications for growth hormone have been discovered, particularly in relation to its anabolic actions. These include post surgery recovery, enhanced bone fracture healing, Crohns disease, dilated cardiomyopathy, infertility and ageing. The hormone exerts these actions through its receptor, which is a class1 cytokine receptor, similar to many receptors important in regulating immunity, inflammation, metabolism and cancers. In principle, if we can find out how the GH receptor works, this information would help in designing drugs to treat many immune and inflammatory disorders. With current NHMRC support we have developed a model which describes how GH activates the receptor at a molecular level. The model involves two pre-associated receptors at the cell surface binding to the hormone, with the result that the receptors are rotated relative to each other, and this brings the two JAK2 signalling units attached tothe receptor inside the cell into alignment, so they can activate each other. We can activate the receptor without hormone by artificially rotating it. This model is a prediction based on several techniques, but lacks proof of rotation. There are also a number of issues relating to the need for rigidity in the receptors, so the torque can be transmitted into the cell, since many believe there is no rigidity just above the membrane. We predict there is , but need to prove this. This information is vital for designing small orally active mimics of growth hormone, and for developing GH antagonists, likely to be useful for breast and colon cancer. Finally, we have evidence that the specificity of receptor signalling can be changed by mutating the outer part of the receptor (novel). We believe this can be used to change the activity spectrum of GH, hence decrease side effects, by developing analogs which activate one pathway or the other.Read moreRead less
Constitutive Activation Of The Growth Hormone Receptor
Funder
National Health and Medical Research Council
Funding Amount
$566,277.00
Summary
Growth hormone regulates growth, metabolism, bone, stem cells and longevity, and cancer. These actions are mediated by the GH receptor, and here we seek to understand how it is activated by the hormone through receptor constructs which are active without hormone, to different degrees. We will use these to elucidate its signaling properties, its ability to promote cancer, to grow muscle, and whether cases of giantism and cancer are a consequence of the activating mutations we have identified.