Pasteurella multocida Toxin-induced Activation of RhoA Is Mediated via Two Families of Gα Proteins, Gαq and Gα12/13

• Published in: The Journal of biological chemistry 2005-11, Vol.280 (44), p.36701-36707
• Main Authors: Orth, Joachim H.C., Lang, Simona, Taniguchi, Masatoshi, Aktories, Klaus
• Format: Article
• Language: English
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M507203200

Pasteurella multocida toxin (PMT) is a potent mitogen, which is known to activate phospholipase Cβ by stimulating the α-subunit of the heterotrimeric G protein Gq. PMT also activates RhoA and RhoA-dependent pathways. Using YM-254890, a specific inhibitor of Gq/11, we studied whether activation of RhoA involves G proteins other than Gq/11. YM-254890 inhibited PMT or muscarinic M3-receptor-mediated stimulation of phospholipase Cβ 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 Gαq/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 G13GA, indicating involvement of Gα12/13 in the PMT effect on RhoA. In Gα12/13 gene-deficient cells, PMT-induced stimulation of RhoA, luciferase activity, and ERK phosphorylation were blocked by YM-254890, indicating the involvement of Gq. Infection with a virus harboring the gene of Gα13 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 Gαq and indicate that, in addition to Gαq, the Gα12/13 G proteins are targets of PMT.