Mechanically evoked 5-hydroxytryptamine release is mediated by caveolin-associated cholesterol rich membrane domains.
5-Hydroxytryptamine (5-HT) from enterochromaffin cells activates neural reflexes that govern intestinal motility and secretion. Mechanical stimulation of human enterochromaffin cell-derived BON cells activates a G alpha q-signalling pathway coupled to 5-HT release. Molecular mechanisms identifying elements of mechanosensory transduction are unknown. The aim of this study was to determine the role of caveolin and caveolin-associated cholesterol rich microdomains in mechanically stimulated 5-HT release from BON cells. Caveolin-1 transcripts and immunofluorescence were found in BON cells. In the static state, caveolins-1 and -2 co-precipitated with G alpha q in cholesterol rich cell fractions, but not with G alpha s, G alpha i/o and G beta. Mechanical stimulation transiently uncoupled G alpha q from caveolin-1 and increased 5-HT release. Disassembly of caveolin-associated membrane microdomains by filipin or by cholesterol depletion with methyl-beta-cyclodextrin decreased mechanically evoked 5-HT release. These results suggest that caveolin and caveolin-associated cholesterol rich membrane microdomains are key regulators in mechanically evoked 5-HT release from enterochromaffin cells.
Kim
M
M
Department of Surgery, Rhode Island Hospital, Brown Medical School, Providence, Rhode Island, USA.
Christofi
F L
FL
Xue
J
J
Robinson
J M
JM
Cooke
H J
HJ
D021941:Caveolae / Q000378:metabolism*; D051242:Caveolin 1 / Q000032:analysis; D002462:Cell Membrane / Q000378:metabolism*; D002478:Cells, Cultured; D002784:Cholesterol / Q000032:analysis; D004759:Enterochromaffin Cells / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D006801:Humans; D008563:Membrane Lipids / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012701:Serotonin / Q000378:metabolism*; D015398:Signal Transduction
D051242:Caveolin 1; D008563:Membrane Lipids; D012701:Serotonin; D002784:Cholesterol