Pasteurella multocida toxin-induced activation of RhoA is mediated via two families of G{alpha} proteins, G{alpha}q and G{alpha}12/13.
Pasteurella multocida toxin (PMT) is a potent mitogen, which is known to activate phospholipase Cbeta by stimulating the alpha-subunit of the heterotrimeric G protein G(q). PMT also activates RhoA and RhoA-dependent pathways. Using YM-254890, a specific inhibitor of G(q/11), we studied whether activation of RhoA involves G proteins other than G(q/11). YM-254890 inhibited PMT or muscarinic M3-receptor-mediated stimulation of phospholipase Cbeta at similar concentrations in HEK293m3 cells. In these cells, PMT-induced RhoA activation and enhancement of RhoA-dependent luciferase activity were partially inhibited by YM-254890. In Galpha(q/11)-deficient fibroblasts, PMT induced activation of RhoA, increase in RhoA-dependent luciferase activity, and increase in ERK phosphorylation. None of these effects were influenced by YM-254890. However, RhoA activation by PMT was inhibited by RGS2, RGS16, lscRGS, and dominant negative G(13)(GA), indicating involvement of Galpha(12/13) in the PMT effect on RhoA. In Galpha(12/13) gene-deficient cells, PMT-induced stimulation of RhoA, luciferase activity, and ERK phosphorylation were blocked by YM-254890, indicating the involvement of G(q). Infection with a virus harboring the gene of Galpha(13) reconstituted the increase in RhoA-dependent luciferase activity by PMT even in the presence of YM-254890. The data show that YM-254890 is able to block PMT activation of Galpha(q) and indicate that, in addition to Galpha(q), the Galpha(12/13) G proteins are targets of PMT.
Orth
Joachim H C
JH
Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Albert-Ludwigs Universität Freiburg, D-79104 Freiburg, Germany.
Lang
Simona
S
Taniguchi
Masatoshi
M
Aktories
Klaus
K
D000818:Animals; D001426:Bacterial Proteins / Q000494:pharmacology*; D001427:Bacterial Toxins / Q000494:pharmacology*; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000187:drug effects*; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D044365:GTP-Binding Protein alpha Subunits, G12-G13 / Q000235:genetics / Q000502:physiology*; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000235:genetics / Q000502:physiology*; D006801:Humans; D015151:Immunoblotting; D007295:Inositol Phosphates / Q000378:metabolism; D007527:Isoenzymes / Q000378:metabolism; D007668:Kidney / Q000378:metabolism; D008156:Luciferases / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D016979:Pasteurella multocida / Q000378:metabolism; D010456:Peptides, Cyclic / Q000494:pharmacology; D054799:Phospholipase C beta; D010766:Phosphorylation; D010957:Plasmids; D043587:Receptor, Muscarinic M3 / Q000378:metabolism; D012190:Retroviridae / Q000235:genetics; D010738:Type C Phospholipases / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*
D001426:Bacterial Proteins; D001427:Bacterial Toxins; D007295:Inositol Phosphates; D007527:Isoenzymes; C062258:Pasteurella multocida toxin; D010456:Peptides, Cyclic; D043587:Receptor, Muscarinic M3; C475455:YM-254890; D008156:Luciferases; D048052:Mitogen-Activated Protein Kinase 3; D010738:Type C Phospholipases; D054799:Phospholipase C beta; D044365:GTP-Binding Protein alpha Subunits, G12-G13; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D020742:rhoA GTP-Binding Protein