Alterations of N-ethylmaleimide-sensitive atpase following transient cerebral ischemia

Abstract

Neuronal repair following injury requires recruitment of large amounts of membranous proteins into synaptic and other cell membranes, which is carried out by the fusion of transport vesicles to their target membranes. A critical molecule responsible for assemblage of membranous proteins is N-ethylmaleimide-sensitive factor (NSF) which is an ATPase. To study whether NSF is involved in ischemic neurological deficits and delayed neuronal death, we investigated alterations of NSF after transient cerebral ischemia by means of biochemical methods, as well as confocal and electron microscopy. We found that transient cerebral ischemia induced depletion of free NSF and concomitantly relocalization of NSF into the Triton X-100-insoluble fraction including postsynaptic densities in CA1neurons during the postischemic period. The NSF alterations are accompanied by accumulation of large quantities of intracellular vesicles in CA1 neurons that are undergoing delayed neuronal death after transient cerebral ischemia. Therefore, permanent depletion of free NSF and relocalization of NSF into the Triton X-100-insoluble fraction may disable the vesicle fusion machinery necessary for repair of synaptic injury, and ultimately leads to synaptic dysfunction and delayed neuronal death in CA1 neurons after transient cerebral ischemia.