Novel Upstream Regulatory And Down-stream Signaling Mechanisms Of The Src-family Protein Kinases
Funder
National Health and Medical Research Council
Funding Amount
$363,639.00
Summary
Normal cell growth and division are governed by the balanced action of two groups of enzymes - the enzymes encoded by the proto-oncogenes (precursors of cancer-causing genes) and the tumour suppressor genes. Abnormalities in the regulation of these enzymes cause cancer. Indeed, over-stimulation of a group of proto-oncogenic enzymes called the Src-family kinases (SFKs) is the major contributing factor to most human cancers. In this application, we propose to study how inactivation of SFKs by thei ....Normal cell growth and division are governed by the balanced action of two groups of enzymes - the enzymes encoded by the proto-oncogenes (precursors of cancer-causing genes) and the tumour suppressor genes. Abnormalities in the regulation of these enzymes cause cancer. Indeed, over-stimulation of a group of proto-oncogenic enzymes called the Src-family kinases (SFKs) is the major contributing factor to most human cancers. In this application, we propose to study how inactivation of SFKs by their native inhibitor CHK suppresses cancer formation and how over-stimulation of SFKs causes cancer. Exactly how CHK inactivates SFKs remains unclear. Recently, we discovered a novel mechanism employed by CHK to inhibit SFKs. In this mechanism, CHK binds to SFKs tightly and the binding alone is sufficient to completely shut down SFK activity. As this novel inhibitory mechanism of CHK can be exploited for the development of synthetic SFK inhibitors for cancer treatment, we propose to unravel how CHK tightly binds to SFKs and how the binding inhibits the cancer-promoting activity of SFKs. How over-stimulation of SFKs induces the development of human cancer has been an important outstanding question in cancer research. Recently, we and two groups of researchers in Texas achieved breakthroughs in answering this question. The Texan groups discovered that the over-stimulated SFKs cause cancer by shutting down the anti-tumour activity of a tumour suppressor called PTEN. We complemented their findings by discovering how SFKs shut down PTEN activity - SFKs shut down PTEN activity by a chemical modification process called phosphorylation. In this application, we propose to study how SFKs modify PTEN and how phosphorylation shuts down the tumour suppressor activity of PTEN. In summary, our studies will benefit the development of two types of anti-cancer therapeutics: (i) those mimicking CHK binding and inhibition of SFKs, and (ii) those interfering with phosphorylation of PTEN by SFKs.Read moreRead less
During reverse transcription, the positive-strand HIV-1 RNA genome is converted into a double-stranded DNA copy which can be permanently insert into the host cell genome. Our laboratory and others have shown that reverse transcription requires a complex array of molecules, which includes the viral RNA. These RNA can be organised into elaborate structures that have only been partially defined. Genetic experiments have revealed that one of these RNA structures, called TAR, is required for optimal ....During reverse transcription, the positive-strand HIV-1 RNA genome is converted into a double-stranded DNA copy which can be permanently insert into the host cell genome. Our laboratory and others have shown that reverse transcription requires a complex array of molecules, which includes the viral RNA. These RNA can be organised into elaborate structures that have only been partially defined. Genetic experiments have revealed that one of these RNA structures, called TAR, is required for optimal initiation of reverse transcription (the first step of reverse transcription), but the precise mechanism is unknown. Recent advances in our laboratory have enabled a comprehensive study of the role played by TAR RNA in reverse transcription. Our leading hypotheses regarding the mechanism is required that TAR interacts with other RNA sequences or Reverse transcriptase in the initiation complex so that the reaction is optimal. This proposal will investigate these two leading hypotheses. Given the enormity of the HIV pandemic and the many recent reports from the United States that most patient isolated virus is resistant to at least one antiretroviral drug, these studies have as an outcome the identification and characterisation of important new key molecules towards which antiretroviral strategies can be designed.Read moreRead less
Investigation Of The Role Of The GPIb/V/IX-filamin-1 Interaction In Regulating Platelet Function In Vivo
Funder
National Health and Medical Research Council
Funding Amount
$267,750.00
Summary
Platelets play an essential role in blood clotting and blod vessel repair. Upon injury to a blood vessel, platelets rapidly adhere to the area of damage where they undergo dramatic changes in their shape and internal structure that facilitates spreading over the area of injury and subsequent formation of a stable blood clot. Our research studies are aimed at understanding more closely the factors that regulate the adhesiveness of platelets, since this is an important determinant not only in norm ....Platelets play an essential role in blood clotting and blod vessel repair. Upon injury to a blood vessel, platelets rapidly adhere to the area of damage where they undergo dramatic changes in their shape and internal structure that facilitates spreading over the area of injury and subsequent formation of a stable blood clot. Our research studies are aimed at understanding more closely the factors that regulate the adhesiveness of platelets, since this is an important determinant not only in normal blood clot formation but also in the development of harmful blood clots (thrombosis) associated with the development of diseases such as heart attack and stroke. Our particular focus is on the interaction between adhesion receptors on the surface of the platelet and components of the intracellular platelet structure referred to as the cytoskeleton and how this interaction might regulate the reactivity of platelets and their ability to adhere to blood vessels. We believe this may be an important mechanism that regulates platelet adhesion and notmal blood clotting.Read moreRead less
The Mechanism Of Tat-enhanced Reverse Transcription In HIV-1
Funder
National Health and Medical Research Council
Funding Amount
$282,750.00
Summary
During reverse transcription, the positive-strand HIV-1 RNA genome is converted into a double-stranded DNA copy which can be permanently insert into the host cell genome. Many HIV-1 proteins including Tat contribute to the efficiency of reverse transcription. There are two competing hypotheses to explain how Tat enhances reverse transcription. The indirect mechanism hypothesis holds that Tat-enhanced reverse transcription is due to the combined effects of the Tat-induced expression of cellular g ....During reverse transcription, the positive-strand HIV-1 RNA genome is converted into a double-stranded DNA copy which can be permanently insert into the host cell genome. Many HIV-1 proteins including Tat contribute to the efficiency of reverse transcription. There are two competing hypotheses to explain how Tat enhances reverse transcription. The indirect mechanism hypothesis holds that Tat-enhanced reverse transcription is due to the combined effects of the Tat-induced expression of cellular genes. The direct mechanism hypothesis is that Tat functions directly during RTN, implying it is a virion protein. Our recent genetic and biochemical data provide strong evidence that a novel form of Tat, which we call vTat, has a direct role in RTN. This proposal will investigate these two leading hypotheses. Given the enormity of the HIV pandemic and the many recent reports from the United States that most patient isolated virus is resistant to at least one antiretroviral drug, these studies have as an outcome the identification and characterisation of important new key molecules towards which antiretroviral strategies can be designed.Read moreRead less
Examination Of The Molecular Pharmacology Of Anthracyclines Induced Via Their Interaction With Iron
Funder
National Health and Medical Research Council
Funding Amount
$618,401.00
Summary
Anthracyclines are highly effective anti-cancer drugs, but their use is limited by toxic effects on the heart. This is thought to be due to these drugs directly binding iron (Fe). Indeed, we showed that anthracyclines induced marked changes in the way heart cells utilise Fe (DR1-3, 38; Mol. Pharmacol. 2002, 2003, 2004, 2005). We were the first to show that anthracyclines prevent Fe release from the criticial Fe storage protein ferritin. This prevents the use of Fe for vital processes eg. DNA and ....Anthracyclines are highly effective anti-cancer drugs, but their use is limited by toxic effects on the heart. This is thought to be due to these drugs directly binding iron (Fe). Indeed, we showed that anthracyclines induced marked changes in the way heart cells utilise Fe (DR1-3, 38; Mol. Pharmacol. 2002, 2003, 2004, 2005). We were the first to show that anthracyclines prevent Fe release from the criticial Fe storage protein ferritin. This prevents the use of Fe for vital processes eg. DNA and haem synthesis. Hence, this effect probably contributes to the cytotoxic activity of anthracyclines on the heart. We showed that novel drugs developed in my lab that bind Fe called chelators show high activity in animals (DR4) and prevent anthracycline-mediated Fe accumulation in ferritin. Importantly, Fe chelators have been shown to inhibit anthracycline-mediated cardiotoxicity. Indeed, the clinically used cardioprotective agent, ICRF-187, is actually an Fe chelator (5, DR6). However, ICRF-187 is not totally successful in terms of its cardioprotective effects and can cause myelosuppression (5, DR6). While the clinically used chelator, desferrioxamine (DFO), can prevent anthracycline-mediated cardiotoxicity, its poor membrane permeability limits its effectiveness. Our chelators are highly permeable and overcome the disadvantages of DFO (DR4). Thus, they are vital to examine for preventing anthracycline-mediated cardiotoxicity. In this proposal we will examine the changes in Fe metabolism induced by anthracyclines and test the hypothesis that novel Fe chelators may prevent the cardiotoxicity of these agents. We also aim to be the first to assess if preparation of anthracyclines which cannot bind iron prevents their cardiotoxicity. This will be done by preparing metal complexes of these drugs which prevent Fe-binding eg. anthracycline-zinc complexes. These studies are important for the development of less cardiotoxic forms of these very useful anti-tumour agents.Read moreRead less
Control Of CD4 Function By Disulphide-Bond Switching
Funder
National Health and Medical Research Council
Funding Amount
$252,761.00
Summary
CD4 is a cell-surface protein that has two functions in the human body, a good one and a bad one. Its good function is as a checkpoint for development of the immune system and for response of the immune system to infection. It helps immune cells known as T cells to recognize and dispose of a foreign particle in the body. Its bad function is that it is one of two proteins that enable the HIV virus to enter and destroy immune cells. The HIV virus binds to CD4 on immune cells, which leads to fusion ....CD4 is a cell-surface protein that has two functions in the human body, a good one and a bad one. Its good function is as a checkpoint for development of the immune system and for response of the immune system to infection. It helps immune cells known as T cells to recognize and dispose of a foreign particle in the body. Its bad function is that it is one of two proteins that enable the HIV virus to enter and destroy immune cells. The HIV virus binds to CD4 on immune cells, which leads to fusion of the viral and immune cell surfaces and entry of the virus into the cell. Once inside the immune cell the virus reproduces itself and goes on to kill more immune cells. AIDS results when too many immune cells are killed. We have discovered that CD4 exists in three different forms on the immune cell surface; an oxidized, reduced or dimeric form. These different forms result from a molecular switch we discovered in CD4. We have suggested that the good and bad functions of CD4 are mediated by different forms of CD4. The good function is mediated by dimeric CD4, while the bad function is mediated by reduced CD4. The purpose of this application is to test this hypothesis. If we are correct then our findings will have significant implications for our understanding of how the immune system responds to a foreign invader and how HIV-AIDS destroys the immune system. This knowledge could be used to develop drugs that suppress the immune system when required, such as in organ transplantation, and that fight HIV-AIDS.Read moreRead less
Investigating The Mechanisms Of Regulation Of Mycobacterial Cell Wall Biosynthesis
Funder
National Health and Medical Research Council
Funding Amount
$597,349.00
Summary
Tuberculosis (TB) kills around two million people each year while the causative bacterial species, Mycobacterium tuberculosis, infects one-third of the entire human population. An alarmingly high rate of TB exists in Australia's indigenous population. This proposal aims to identify and characterise essential processes involved in synthesis of the outer coat of the bacterium which are potential targets for new drugs for the treatment of this devastating disease.