Probing Central And Peripheral Calcium Channel Sybtypes With Novel Omega Conotoxins
Funder
National Health and Medical Research Council
Funding Amount
$383,168.00
Summary
New toxins including omega-conotoxin CVID have been discovered from fish eating cone snails found on the Great Barrier Reef. These toxins discriminate between ion channel receptors on nerve cells that allow calcium ions to enter the cell and nerve transmission to continue. Of great importance is the fact that CVID specifically and potently blocks nerves that transmit pain responses. This project is involved with understanding the nolecular basis for this action with the goal of underpinning the ....New toxins including omega-conotoxin CVID have been discovered from fish eating cone snails found on the Great Barrier Reef. These toxins discriminate between ion channel receptors on nerve cells that allow calcium ions to enter the cell and nerve transmission to continue. Of great importance is the fact that CVID specifically and potently blocks nerves that transmit pain responses. This project is involved with understanding the nolecular basis for this action with the goal of underpinning the design of even more selective agents that will ameliorate pain while reducing side effects.Read moreRead less
Mimicking Protein Surfaces With Cyclic Peptides: W-conotoxin GVIA Mimics As Novel Analgesic And Neuroprotective Agents
Funder
National Health and Medical Research Council
Funding Amount
$216,412.00
Summary
The omega-conotoxins are small polypeptides (of around 25 residues) cross-linked by three disulfide bonds. At least two of these, omega-conotoxins GVIA and MVIIA, are potent and selective blockers of N-type voltage-gated calcium channels. Administered to the CNS via an intrathecal catheter, MVIIA and GVIA are analgesic in acute, chronic and neuropathic pain models, and protective following ischaemia-induced neuronal injury, such as occurs following stroke. They do not suffer from the development ....The omega-conotoxins are small polypeptides (of around 25 residues) cross-linked by three disulfide bonds. At least two of these, omega-conotoxins GVIA and MVIIA, are potent and selective blockers of N-type voltage-gated calcium channels. Administered to the CNS via an intrathecal catheter, MVIIA and GVIA are analgesic in acute, chronic and neuropathic pain models, and protective following ischaemia-induced neuronal injury, such as occurs following stroke. They do not suffer from the development of tolerance, in contrast with the opioids, such as morphine, which lose their analgesic potency over time and have undesirable side effects. We have determined the three-dimensional structure of GVIA and mapped onto that structure its calcium channel binding surface. This information is a starting point for the structure-based design of truncated and stabilised peptidic analogues of GVIA, which should have several advantages over the native polypeptides as candidates for the treatment of chronic pain and ischaemia-induced neuronal damage. In the course of this work we shall also generate a range of libraries of experimentally determined and predicted structures based on small, cyclic peptides. These libraries will be valuable tools for mimicking key functional regions of protein surfaces in small molecules that are easily (and cheaply) synthesised and have potentially favourable bioavailability. Thus, this project will also increase our understanding of the attributes of small cyclic peptides as mimics of functionally important protein surfaces and provide valuable tools for the design and evaluation of such peptides.Read moreRead less
Controlling the concentration of calcium inside cells is extremely important for normal cell function. For example, a brief increase in calcium concentration inside muscle cells is essential for muscle contraction and the normal heart beat. This calcium is kept stored in sacs inside cells and is rapidly released when needed through calcium channels known as ryanodine receptors. We have discovered that some proteins (glutathione transferases and intracellular chloride channel proteins) inside cel ....Controlling the concentration of calcium inside cells is extremely important for normal cell function. For example, a brief increase in calcium concentration inside muscle cells is essential for muscle contraction and the normal heart beat. This calcium is kept stored in sacs inside cells and is rapidly released when needed through calcium channels known as ryanodine receptors. We have discovered that some proteins (glutathione transferases and intracellular chloride channel proteins) inside cells can affect how much calcium flows through these calcium channels. The proteins were thought to have other functions and our discovery of their effect on ryanodine receptor calcium channels has caused considerable excitement. We now plan to explore how they do this. We will mutate specific regions of the proteins to discover which regions are important and which are not. We will also look at whether closely related proteins have similar effects. The new class of ion channel modulator that we are studying has the capacity to alter not only respiration, movement and cardiac contraction, but also other aspects cardiovascular function, neuronal activity and immune responses. Understanding the way in which soluble proteins can interact with ion channels may reveal a novel target for drugs that affect ryanodine receptor calcium channel function and allow the rational design of specific drugs to regulate ion channels or ion channel modulators.Read moreRead less