RhoA exerts a permissive effect on volume-regulated anion channels in vascular endothelial cells.
Cell swelling triggers in most cell types an outwardly rectifying anion current, I(Cl,swell), via volume-regulated anion channels (VRACs). We have previously demonstrated in calf pulmonary artery endothelial (CPAE) cells that inhibition of the Rho/Rho kinase/myosin light chain phosphorylation pathway reduces the swelling-dependent activation of I(Cl,swell). However, these experiments did not allow us to discriminate between a direct activator role or a permissive effect. We now show that the Rho pathway did not affect VRAC activity if this pathway was activated by transfecting CPAE cells with constitutively active isoforms of Galpha (a Rho activating heterotrimeric G protein subunit), Rho, or Rho kinase. Furthermore, biochemical and morphological analysis failed to demonstrate activation of the Rho pathway during hypotonic cell swelling. Finally, manipulating the Rho pathway with either guanosine 5'-O-(3-thiotriphosphate) or C3 exoenzyme had no effect on VRACs in caveolin-1-expressing Caco-2 cells. We conclude that the Rho pathway exerts a permissive effect on VRACs in CPAE cells, i.e., swelling-induced opening of VRACs requires a functional Rho pathway, but not an activation of the Rho pathway.
Carton
Iris
I
Laboratory of Physiology, Katholieke Universiteit Leuven, Campus Gasthuisberg, B-3000 Leuven, Belgium.
Trouet
Dominique
D
Hermans
Diane
D
Barth
Holger
H
Aktories
Klaus
K
Droogmans
Guy
G
Jorgensen
Nanna K
NK
Hoffmann
Else K
EK
Nilius
Bernd
B
Eggermont
Jan
J
D000818:Animals; D000838:Anions / Q000378:metabolism*; D018938:Caco-2 Cells; D002417:Cattle; D051242:Caveolin 1; D022461:Caveolins / Q000494:pharmacology; D002478:Cells, Cultured; D018118:Chloride Channels / Q000502:physiology; D004268:DNA-Binding Proteins / Q000502:physiology; D004730:Endothelium, Vascular / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D044365:GTP-Binding Protein alpha Subunits, G12-G13; D006801:Humans; D007038:Hypotonic Solutions / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins; D007473:Ion Channels / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000502:physiology; D020741:rho GTP-Binding Proteins / Q000502:physiology; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein / Q000502:physiology*
D000838:Anions; C495540:CAV1 protein, human; D051242:Caveolin 1; D022461:Caveolins; D018118:Chloride Channels; D004268:DNA-Binding Proteins; D007038:Hypotonic Solutions; D047908:Intracellular Signaling Peptides and Proteins; D007473:Ion Channels; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D044365:GTP-Binding Protein alpha Subunits, G12-G13; D020741:rho GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein