Receptor-dependent RhoA activation in G12/G13-deficient cells: genetic evidence for an involvement of Gq/G11.
The small GTPase RhoA is involved in the regulation of various cellular functions like the remodeling of the actin cytoskeleton and the induction of transcriptional activity. G-protein-coupled receptors (GPCRs), which are able to activate Gq/G11 and G12/G13 are major upstream regulators of RhoA activity, and G12/G13 have been shown to couple GPCRs to the activation of Rho by regulating the activity of a subfamily of RhoGEF proteins. However, the possible contribution of Gq/G11 to the regulation of RhoA activity via GPCRs is controversial. We have used a genetic approach to study the role of heterotrimeric G-proteins in the activation of RhoA via endogenous GPCRs. In pertussis toxin-treated Galpha12/Galpha13-deficient as well as in Galphaq/Galpha11-deficient mouse embryonic fibroblasts (MEFs), in which coupling of receptors is restricted to Gq/G11 and G12/G13, respectively, receptor activation results in Rho activation. Rho activation induced by receptor agonists via Gq/G11 occurs with lower potency than Rho activation via G12/G13. Activation of RhoA via Gq/G11 is not affected by the phospholipase-C blocker U73122 or the Ca2+-chelator BAPTA, but can be blocked by a dominant-negative mutant of the RhoGEF protein LARG. Our data clearly show that G12/G13 as well as Gq/G11 alone can couple GPCRs to the rapid activation of RhoA. Gq/G11-mediated RhoA activation occurs independently of phospholipase C-beta and appears to involve LARG.
Vogt
Stephan
S
Institute of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany.
Grosse
Robert
R
Schultz
Günter
G
Offermanns
Stefan
S
D000818:Animals; D001920:Bradykinin / Q000494:pharmacology; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000172:deficiency* / Q000502:physiology; D004622:Embryo, Mammalian; D004789:Enzyme Activation; D005347:Fibroblasts / Q000378:metabolism; D044365:GTP-Binding Protein alpha Subunits, G12-G13; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D015870:Gene Expression; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000502:physiology; D020962:Heterotrimeric GTP-Binding Proteins / Q000172:deficiency* / Q000502:physiology*; D007527:Isoenzymes / Q000378:metabolism; D008246:Lysophospholipids / Q000494:pharmacology; D051379:Mice; D018345:Mice, Knockout; D054799:Phospholipase C beta; D018002:Receptors, Bradykinin / Q000235:genetics; D011956:Receptors, Cell Surface / Q000235:genetics / Q000502:physiology*; D043562:Receptors, G-Protein-Coupled; D049368:Receptors, Lysophosphatidic Acid; D018179:Receptors, Thrombin / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D064067:Rho Guanine Nucleotide Exchange Factors; D013917:Thrombin / Q000494:pharmacology; D014162:Transfection; D010738:Type C Phospholipases / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*
C577223:Arhgef12 protein, mouse; D004268:DNA-Binding Proteins; D020662:Guanine Nucleotide Exchange Factors; D007527:Isoenzymes; D008246:Lysophospholipids; D018002:Receptors, Bradykinin; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D049368:Receptors, Lysophosphatidic Acid; D018179:Receptors, Thrombin; D064067:Rho Guanine Nucleotide Exchange Factors; D010738:Type C Phospholipases; D054799:Phospholipase C beta; D013917:Thrombin; D044365:GTP-Binding Protein alpha Subunits, G12-G13; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D020962:Heterotrimeric GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein; D001920:Bradykinin