Regulation Of ADAMTS-5 Activity By Keratan Sulphate-binding Exosites
Funder
National Health and Medical Research Council
Funding Amount
$213,342.00
Summary
Arthritis and musculoskeletal conditions are the predominant cause of disability in Australia. The burden of arthritis is felt not only by patients, their families and carers, but also the labour market and the national economy. There is a pressing need to identify new targets for design of inexpensive arthritis therapies. The TNF antagonists have proved effective in managing rheumatoid arthritis (RA), but they are expensive, administered by injection, and in general, only prescribed in Australi ....Arthritis and musculoskeletal conditions are the predominant cause of disability in Australia. The burden of arthritis is felt not only by patients, their families and carers, but also the labour market and the national economy. There is a pressing need to identify new targets for design of inexpensive arthritis therapies. The TNF antagonists have proved effective in managing rheumatoid arthritis (RA), but they are expensive, administered by injection, and in general, only prescribed in Australia for patients who respond poorly to DMARDs. Their long-term efficacy and safety is not yet determined. There are no treatments for osteoarthritis (OA), the disease that occurs more frequently with age and is characterised by destruction of cartilage and aggrecan. New drugs that protect against aggrecan breakdown are urgently needed for OA and they would also be valuable adjunct therapies to the DMARDs for treatment of RA. We have discovered that the major aggrecan-degrading enzyme is ADAMTS-5. ADAMTS-5 is, therefore, a potential target for arthritis therapies. Unfortunately, drugs targeting the active site of ADAMTS-5 are predicted to fail, given the wide tissue distribution of ADAMTS-5, the high level of homology between the active site of ADAMTS enzymes and matrix metalloproteinases (MMPs), and the notorious failure of MMP active site inhibitors in clinical trials. The aim of this project is to determine whether ancillary domains of ADAMTS-5 are a viable alternative target to the active site. We have evidence to suggest that keratan sulphate, which is covalently attached to the aggrecan core protein, can modulate aggrecan cleavage by ADAMTS enzymes. We aim to identify opportunities for developing antagonists that block keratan sulphate binding, or keratan sulphate analogues that block enzyme binding to its substrate. The data will inform the pharmaceutical industry on new directions for modulating aggrecanolysis by ADAMTS-5.Read moreRead less
Identifying A Novel Aggrecanase In Mouse Cartilage
Funder
National Health and Medical Research Council
Funding Amount
$299,227.00
Summary
Destructive enzymes degrade cartilage in arthritis. Aggrecan is a major structural molecule that gives cartilage its cushioning properties, and aggrecan is also destroyed by harmful enzymes in arthritis. We have discovered a new enzyme that degrades aggrecan. This project aims to identify and study this new enzyme, and to determine its role in aggrecan degradation.
Cartilage Destruction In Joint Disease: Studies With ADAMTS-4 And ADAMTS-5 Deficient Mice
Funder
National Health and Medical Research Council
Funding Amount
$540,600.00
Summary
In healthy joints the proteoglycan, aggrecan, gives cartilage compressive resilience to permit weight bearing, but in disease aggrecan is degraded by ADAMTS enzymes. The challenges to the field are to determine which ADAMTS is involved, when these enzymes are active and precisely where they come from. We hypothesise that ADAMTS-4 and-or ADAMTS-5 is involved in cartilage pathology. To test this hypothesis we aim to [1] Generate mice containing mutant ADAMTS-4 and-or -5 in all cells, or [2] in car ....In healthy joints the proteoglycan, aggrecan, gives cartilage compressive resilience to permit weight bearing, but in disease aggrecan is degraded by ADAMTS enzymes. The challenges to the field are to determine which ADAMTS is involved, when these enzymes are active and precisely where they come from. We hypothesise that ADAMTS-4 and-or ADAMTS-5 is involved in cartilage pathology. To test this hypothesis we aim to [1] Generate mice containing mutant ADAMTS-4 and-or -5 in all cells, or [2] in cartilage cells only. [3] Analyse mutant mice for changes in skeletal architecture, changes in ADAMTS mRNA and protein, and changes in aggrecan breakdown products. [4] Assess disease severity in mutant mice in in vivo models of joint disease. We already have mice with ADAMTS-4, or -5, mutated in all tissues and we are generating the double mutants now. We will also generate single and double mutants with dysfunctional enzymes in cartilage only. We will examine skeletal structure by histology and X-ray at all ages and monitor for expression of ADAMTS-1 and -9 to detect any compensatory over-production of other potential 'aggrecanases'. We will also do co-culture experiments in which cartilage and synovial cells from combinations of mutant and control mice will be incubated together to determine whether synovial ADAMTS can penetrate and degrade aggrecan in cartilage. Finally we will induce arthritis in mutant and control mice and monitor them to detect differences in the time of disease onset, the rate of disease progression and overall disease severity. A comparison of whole-mouse with cartilage only mutants in the in vivo models will complement the in vitro co-culture studies and determine whether other joint tissues such as synovium and joint capsule can also produce ADAMTS enzymes that destroy cartilage. This is not known. Together these experiments will reveal if, where and when ADAMTS-4 and-or -5 are active, and whether indeed they are the best targets for drug development.Read moreRead less
Mechanisms Underlying The Biochemical Activity Of Scabrosin Esters And Other Epipolythiodioxopiperazine Toxins.
Funder
National Health and Medical Research Council
Funding Amount
$256,527.00
Summary
Fungi produce a variety of chemicals which are toxic to animals. The fungi have probably developed the ability to synthesize and secrete these toxins as part of a chemical defence mechanism and-or in order to limit other microbial life forms because of nutrient competition. Some of these toxins will selectively kill microbes such as bacteria and other fungi as well as simpler life forms such as viruses, which can cause pathological changes to human beings. Fungal toxins may also be useful for co ....Fungi produce a variety of chemicals which are toxic to animals. The fungi have probably developed the ability to synthesize and secrete these toxins as part of a chemical defence mechanism and-or in order to limit other microbial life forms because of nutrient competition. Some of these toxins will selectively kill microbes such as bacteria and other fungi as well as simpler life forms such as viruses, which can cause pathological changes to human beings. Fungal toxins may also be useful for control of proliferative diseases such as cancer. Because fungi have had many millions of years to select for the most efficient toxins, they have been a valuable source of potent toxins for study. Some of these toxins are now in use clinically to treat human diseases ie penicillin and cyclosporin A. A fundamental understanding of fungal toxins is important to ensure the availability of new drugs to combat resistant strains of bacteria and to provide clues for the synthesis of new drugs to treat cancer which can also develop resistance to currently used drugs.Read moreRead less
Snapshots of an enzyme in action: structural and mechanistic studies on the catalytic cycle of Escherichia coli ketol-acid reductoisomerase. Enzymes are required for almost every process that occurs in a living organism. For this reason, understanding how enzymes work is essential if we are to understand life itself. In this project we will investigate the enzyme KARI by capturing a series of snapshots of its atomic structure as it progresses through its working cycle. In addition, we will make ....Snapshots of an enzyme in action: structural and mechanistic studies on the catalytic cycle of Escherichia coli ketol-acid reductoisomerase. Enzymes are required for almost every process that occurs in a living organism. For this reason, understanding how enzymes work is essential if we are to understand life itself. In this project we will investigate the enzyme KARI by capturing a series of snapshots of its atomic structure as it progresses through its working cycle. In addition, we will make a series of small alterations to the atomic structure that will allow us to understand how the individual parts work together.Read moreRead less
Structure and inhibition of acetohydroxyacid synthase. Acetohydroxyacid synthase (AHAS) has been identified as the target for several widely used herbicides known as the sulfonylureas and imidazolinones. World-wide, these two herbicides account for $US2 billion in annual sales. The aim is to determine the three-dimensional structure of AHAS from several sources and in complex with these herbicides. Furthermore, AHAS appears to be an excellent target for the development of antibacterial compounds ....Structure and inhibition of acetohydroxyacid synthase. Acetohydroxyacid synthase (AHAS) has been identified as the target for several widely used herbicides known as the sulfonylureas and imidazolinones. World-wide, these two herbicides account for $US2 billion in annual sales. The aim is to determine the three-dimensional structure of AHAS from several sources and in complex with these herbicides. Furthermore, AHAS appears to be an excellent target for the development of antibacterial compounds and fungicides. Knowledge of the three dimensional structures of these enzymes will be important in the rational design of more effective inhibitors with improved selectivity.Read moreRead less