Disruption of actin cytoskeleton causes internalization ofCav1.3 (alpha 1D) L-type calcium channels in salamander retinalneurons

[摘要] Purpose: To study the influence of actin cytoskeletonreorganization on the subcellular distribution of Cav1.3 L-typeCa2+ channels in salamander retinal third-order neurons.Methods: Immunocytochemistry with confocal microscopy wasused to demonstrate internalization of the Cav1.3 isoform ofL-type voltage-gated Ca2+ channels in third-order retinal neurons.A specificity of antibody was confirmed with Western blotting and incontrol experiments preabsorbing antibody wit its respective peptide.Whole-cell patch clamp technique was applied to record L-type currentsfrom ganglion cells in slice preparations in the presence of N- and P/Qtype Ca2+ channel blockers.Results: A high level of Cav1.3 labeling was present incone photoreceptor terminals in the outer plexiform layer (OPL), asaggregates of puncta. Punctate Cav1.3 labeling was evidentthroughout the IPL and around the cell bodies in the outer nuclear(ONL), inner nuclear (INL) and on somas and axons of ganglion cellslabeled with rhodamine-conjugated dextran. Doubly labeled sections forsynaptophysin and Cav1.3 revealed colocalization in the OPL andIPL. Depolymerization of the actin cytoskeleton caused adynamin-dependent internalization of Cav1.3 but not Cav1.2subtype of voltage-gated Ca2+ channels in dissociated neurons. Inganglion cells, the inhibition of L-type Ca2+ currents by F-actindisrupters was mediated by Ca2+ channel internalization. Treatmentwith cytochalasin D protected retinal neurons against kainate-inducedexcitotoxicity.Conclusions: Actin cytoskeleton dynamics plays an importantrole in the regulation of subcellular distribution and function ofCav1.3 L-type Ca2+ channels in salamander retinal neurons.Ca2+-dependent actin depolymerization may serve as a negativefeedback mechanism to reduce excessive Ca2+ influx and therebyprotect neurons against glutamate-induced excitotoxicity.

[学科分类] 生物化学/生物物理