Mechanisms of ASIC-mediated neuronal injury

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Abstract Ischemic stroke is a leading cause of death and long-term disability. Current drug treatment is limited to tPA, which has a low success rate and potentially severe side effects. Acidosis is a common feature of neurological disorders such as brain ischemia, and it has been shown to play a critical role in stroke. The mechanisms, however, remained elusive. The discovery that protons activate a distinct family of cation channels, the acid-sensing ion channels (ASICs), has shed new light on acid-signaling and acidosis-mediated brain injury. The studies in our laboratories in the past 10 years have provided convincing evidence suggesting that activation of ASIC1a contributes markedly to acidosis-mediated ischemic brain injury. Following our initial report, others have demonstrated an important role for ASIC1a activation in spinal cord injury, traumatic brain injury, and axon degeneration. Thus, ASIC1a represents a novel therapeutic target. Despite its well-established role in neurological disorders, the detailed mechanisms underlying ASIC1a-mediated neuronal injury in stroke remain unclear. We now have strong evidence suggesting that, besides the well-documented Ca2+ toxicity, a combination of increased ASIC1a surface expression, Zn2+ toxicity, and an ion conducting independent cell death pathway participate in ASIC-mediated neuronal injury in ischemia. The objective of this application is to investigate the detailed molecular mechanisms and pathways underlying ASIC-mediated neuronal injury. Given the limitations of currently available pharmacological inhibitors that target these channels, e.g. the non-specificity of amiloride and large molecule nature of PcTX1, the proposed studies may disclose novel and alternative therapeutic strategies for ischemic brain injury.