Poster abstracts
Poster number 13 submitted by Cameron Ford
Acid Sensing Ion Channel 1a and Mitochondrial Function
Cameron Ford (Neuroscience Graduate Program, The Ohio State University), Candice Askwith (Department of Neuroscience, The Ohio State University)
Abstract:
The acid-sensing ion channels (ASICs) contribute to normal brain function and promote neuronal death in mouse models of stroke, traumatic brain injury, and multiple sclerosis. In these models, interventions targeting ASIC1a have prolonged time windows of neuroprotection. To fully capitalize on the therapeutic potential of ASIC1a, the molecular mechanisms mediating ASIC-dependent neuroprotection must be uncovered. The most established model of ASIC1a-dependent death involves acidosis-dependent activation of ASIC1a on the plasma membrane and induction of abnormal signaling cascades. Others, however, have shown the importance of ASIC1a in the regulation of mitochondrial function and have proposed ASIC1a is a mitochondrial ion channel. To investigate this, we tested the role of ASIC1a in mitochondrial activity in cultured neurons and neuron-derived cells. We found that ASIC1a expression impacts H2O2-mediated cell death (which is acidosis-independent). A direct link to mitochondrial function was observed with seahorse metabolic analysis showing that ASIC1a overexpression decreased ATP production, basal respiration, and maximal respiration. These effects were dependent on the N-terminal intracellular region of ASIC1a. We also investigated the effect of ASIC1a on isolated mitochondrial function. In isolated preparations of brain mitochondria, mice with disruption of ASIC1a showed enhanced sensitivity to mitochondrial Ca2+ overload and increased production of reactive oxygen species. These results indicate that ASIC1a can control mitochondrial function. To investigate how this is occurring, we performed subcellular fractionation followed by western blot analysis. We found little ASIC1a signal detected in ultra-pure mitochondrial fractions, however, we found abundant ASIC1a signal in the mitochondria-associated endoplasmic reticulum membrane (MAM). This is a unique localization for ASIC1a and suggests ASIC1a is controlling mitochondrial function through the MAM. Dysregulation of the MAM is a feature of many of the pathological models involving ASIC1a thus uncovering how MAM localized ASIC1a controls mitochondrial function represents a novel therapeutic avenue.
Keywords: ASIC, Mitochondria , MAM