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Cancer Cell death Cell cycle Cytoskeleton Exo/endocytosis Differentiation Division Organelles Signalling Stem cells Trafficking
Cell Biology International (2007) 31, 374–381 (Printed in Great Britain)
Mechanosensitive channel activity and F-actin organization in cholesterol-depleted human leukaemia cells
Elena Morachevskaya, Anastasiya Sudarikova and Yuri Negulyaev*
Institute of Cytology, Russian Academy of Sciences, Tikhoretsky Avenue 4, St. Petersburg 194064, Russian Federation


Abstract

This study focuses on the functional role of cellular cholesterol in the regulation of mechanosensitive cation channels activated by stretch in human leukaemia K562 cells. The patch-clamp method was employed to examine the effect of methyl-β-cyclodextrin (MβCD), a synthetic cholesterol-sequestering agent, on stretch-activated single currents. We found that cholesterol-depleting treatment with MβCD resulted in a suppression of the activity of mechanosensitive channels without a change in the unitary conductance. The probability that the channel was open significantly decreased after treatment with MβCD. Fluorescent microscopy revealed F-actin reorganization, possibly involving actin assembly, after incubation of the cells with MβCD. We suggest that suppression of mechanosensitive channel activation in cholesterol-depleted leukaemia cells is due to F-actin rearrangement, presumably induced by lipid raft destruction. Our observations are consistent with the notion that stretch-activated cation channels in eukaryotic cells are regulated by the membrane–cytoskeleton complex rather than by tension developed purely in the lipid bilayer.


Key words: Mechanosensitive channel, Human leukaemia cell, Actin cytoskeleton, Cholesterol, Methyl-β-cyclodextrin.

*Corresponding author. Tel./fax: +7 812 297 1497.


doi:10.1016/j.cellbi.2007.01.024


ISSN Print: 1065-6995
ISSN Electronic: 1095-8355
Published by Portland Press Limited on behalf of the International Federation for Cell Biology (IFCB)