title: Mechanosensitive channel activity and F-actin organization in cholesterol-depleted human leukaemia cells.
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-beta-cyclodextrin (MbetaCD), a synthetic cholesterol-sequestering agent, on stretch-activated single currents. We found that cholesterol-depleting treatment with MbetaCD 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 MbetaCD. Fluorescent microscopy revealed F-actin reorganization, possibly involving actin assembly, after incubation of the cells with MbetaCD. 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.
authors.affiliation: Institute of Cytology, Russian Academy of Sciences, Tikhoretsky Avenue 4, St. Petersburg 194064, Russian Federation.
authors.forename: Elena
authors.initials: E
authors.lastname: Morachevskaya
authors.forename: Anastasiya
authors.initials: A
authors.lastname: Sudarikova
authors.forename: Yuri
authors.initials: Y
authors.lastname: Negulyaev
mesh_terms: D000199:Actins / Q000378:metabolism*; D002784:Cholesterol / Q000172:deficiency*; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism*; D020014:K562 Cells / Q000187:drug effects / Q000378:metabolism; D007938:Leukemia / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D047392:beta-Cyclodextrins / Q000494:pharmacology*
chemical_list: D000199:Actins; D007473:Ion Channels; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D002784:Cholesterol