Cholesterol modulates acetylcholine receptor organization and stability at the cell membrane

BAIER JAVIER,; KELLNER; VIRGINA BORRONI,; WILLIG; GARBUS INGRID,; HELL SW; BARRANTES FRANCISCO

Cancun

Congreso; 21st Biennial Meeting of the International Society for Neurochemistry y 38th Annual Meeting of the American Society for Neurochemistry; 2007

American Society for Neurochemistry

The effect of cholesterol (Chol) on acetylcholine receptor (AChR)supramolecular organization has been studied by a combinationof approaches using the clonal cell line CHO-K1/A5, amammalian cell line stably expressing adult murine AChR.Acute (30 min, 371C) exposure to methy-beta-cyclodextrin,commonly used as a diagnostic tool of endocytic mechanisms,dramatically accelerated AChR internalization from the cellsurface. From a functional point of view, gain-of-functionchanges were observed in single-channel recordings upon Choldepletion. Wide-field and confocal microscopy disclosed AChRsubmicron-sized (240?280 nm) domains that remain stable over aperiod of hours at the cell membrane. Stimulated emissiondepletion (STED) fluorescence microscopy resolved the domainsinto AChR ??nanoclusters?? with a peak size distribution ofB55 nm. Cyclodextrin-mediated Chol depletion resulted in asmaller number of nanoclusters with larger size, and changes innanocluster distribution on larger scales (0.5?3.5microns). Cholcontent at the plasmalemma is postulated to modulate cell-surfaceorganization and stability of receptor domains, and fine-tune receptor channel function to temporarily compensate for acuteAChR loss from the cell-surface.