Protein Tyrosine Phosphatases In The Regulation Of Insulin Receptor Signalling And Glucose Uptake
Funder
National Health and Medical Research Council
Funding Amount
$425,250.00
Summary
The key pathological feature of type II diabetes is the lack of cellular response to normal levels of circulating insulin. Insulin binding to its cell surface transmembrane receptor initiates a cascade of events known as cellular signalling that results in amongst other things in the uptake of glucose. Protein tyrosine phosphatases (PTPs) are key negative regulators of insulin-induced signalling events and their inhibition with broad based chemical inhibitors can mimic several actions of insulin ....The key pathological feature of type II diabetes is the lack of cellular response to normal levels of circulating insulin. Insulin binding to its cell surface transmembrane receptor initiates a cascade of events known as cellular signalling that results in amongst other things in the uptake of glucose. Protein tyrosine phosphatases (PTPs) are key negative regulators of insulin-induced signalling events and their inhibition with broad based chemical inhibitors can mimic several actions of insulin and lower blood glucose levels in both normal and diabetic rats. This proposal will examine the roles of PTPs and in particular TCPTP and PTP1B in insulin receptor-mediated signalling and glucose uptake. Moreover we will explore the role of TCPTP in alternate insulin receptor-independent processes for glucose uptake. Our studies will shed light on processes important for the regulation of glucose uptake. Moreover our studies may lead to the development of drugs capable of inhibiting PTPs such as TCPTP, that may allow for enhanced glucose uptake and have therapeutic use in the treatment of type II diabetes.Read moreRead less
Regulation And Function Of The Protein Tyrosine Phosphatase TCPTP In Mitosis
Funder
National Health and Medical Research Council
Funding Amount
$455,250.00
Summary
The cell cycle is a universal process by which cells reproduce and it underlies the growth and development of all living organisms. The most important events of the cell cycle concern the replication of chromosomal DNA during S phase and the separation of replicated DNA into progeny cells at mitosis. Mitosis is morphologically the most dynamic phase of the cell cycle and involves the precise coordination of many processes that are governed by reversible protein phosphorylation. Protein phosphata ....The cell cycle is a universal process by which cells reproduce and it underlies the growth and development of all living organisms. The most important events of the cell cycle concern the replication of chromosomal DNA during S phase and the separation of replicated DNA into progeny cells at mitosis. Mitosis is morphologically the most dynamic phase of the cell cycle and involves the precise coordination of many processes that are governed by reversible protein phosphorylation. Protein phosphatases play an important role in reversible protein phosphorylation and they are essential for mitosis. This grant proposal is focused on understanding the regulation and function of protein phosphatases in mitosis. Our studies will provide novel insight into processes mediating mitosis and may lead to the development of alternative strategies for treating cancer.Read moreRead less
Breast cancer is the most frequent malignancy among women, with an estimated 1 million new cases per year worldwide. A family of enzymes known as protein tyrosine kinases (PTKs) are fundamental in the initiation and progression of tumour growth and they are frequently hyperactivated in breast cancer. This proposal will examine whether inactivation of the enzyme known as TCPTP contributes to PTK hyperactivation and tumorigenicity in breast cancer.
Tyrosine Kinases And Phosphatases In Cell Cycle Checkpoint Responses
Funder
National Health and Medical Research Council
Funding Amount
$513,946.00
Summary
In order for an organism to grow and develop, the cells that make up the tissues and organs need to undergo a process of cellular division, wherein individual cells grow and then divide into two cells. During this process of cellular growth and division the entire genome needs to be duplicated (this occurs during S-phase) and then divided equally into the two daughter cells. In S-phase several so-called 'checkpoint' mechanisms exist which ensure that this occurs in an orderly and precise manner. ....In order for an organism to grow and develop, the cells that make up the tissues and organs need to undergo a process of cellular division, wherein individual cells grow and then divide into two cells. During this process of cellular growth and division the entire genome needs to be duplicated (this occurs during S-phase) and then divided equally into the two daughter cells. In S-phase several so-called 'checkpoint' mechanisms exist which ensure that this occurs in an orderly and precise manner. The so-called 'DNA replication checkpoint' delays S-phase progression in response to 'replication stresses' that may otherwise cause DNA damage. Protein tyrosine kinases (PTKs) are hyperactivated in many human solid tumours and blood malignancies contributing to varied aspects of tumour progression. Our preliminary studies indicate that the inactivation of PTKs by protein tyrosine phosphatases may be essential for the suppression of S-phase progression in response to replication stress. Our goal is to understand the molecular mechanisms by which PTKs and tyrosine phosphatases contribute to S-phase checkpoints. Our studies will provide important insights into DNA replication stress-induced checkpoint responses in mammals and identify unprecedented mechanisms by which hyperactivated PTKs may contribute to tumour development.Read moreRead less
Functional Characterization Of A Signaling Complex Between Receptor Protein Tyrosine Phosphatase-k And E-cadherin.
Funder
National Health and Medical Research Council
Funding Amount
$227,036.00
Summary
Contact between cells in the body controls many aspects of cellular function, including cell adhesion, cell movenments, and the architecture of organs. These contacts involve many different kinds of molecules, such as adhesion molecules, proteins that link the cell surface to the cytoskeleton, and many signaling molecules that participate in cellular recognition. It has become increasingly clear that these different molecules interact with one another and that these interactions are functionally ....Contact between cells in the body controls many aspects of cellular function, including cell adhesion, cell movenments, and the architecture of organs. These contacts involve many different kinds of molecules, such as adhesion molecules, proteins that link the cell surface to the cytoskeleton, and many signaling molecules that participate in cellular recognition. It has become increasingly clear that these different molecules interact with one another and that these interactions are functionally important. In this proposal we will study the association between a signaling molecule, the receptor tyrosine phosphatase RPTPk, and a cell-cell adhesion molecule, E-cadherin. RPTPk removes phosphate molecules from tyrosines, an important event that controls many signaling processes; E-cadherin is a major adhesion molecule responsible for cell-cell contact and patterning, and whose dysfunction is involved in tumor invasion. My collaborators and I have recently demonstrated that RPTPk and E-cadherin bind to one another, but the function of this association is unclear. I will test the general hypothesis that these molecules form a signaling complex, that can regulate both the activity of RPTPk and the adhesive function of E-cadherin to ultimately control the way in which cells associate with one another. This work will make an important contribution to our understanding of how cells signal to one another, and provide insights into how cell-cell adhesion and recognition may be perturbed in disease conditions, such as tumor progression.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
T cells play a central role in the immune response. The primary event in T cell activation is the triggering of a specific T cell receptor (TCR). Our studies will examine whether the protein TCPTP antagonises TCR-instigated T cell responses. Our studies may provide important new insights into alternative approaches for manipulating T cell-mediated immune responses in diseased states.
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.