| First Author | Artamonov MV | Year | 2013 |
| Journal | J Biol Chem | Volume | 288 |
| Issue | 47 | Pages | 34030-40 |
| PubMed ID | 24106280 | Mgi Jnum | J:204980 |
| Mgi Id | MGI:5543839 | Doi | 10.1074/jbc.M113.514596 |
| Citation | Artamonov MV, et al. (2013) Agonist-induced Ca2+ sensitization in smooth muscle: redundancy of Rho guanine nucleotide exchange factors (RhoGEFs) and response kinetics, a caged compound study. J Biol Chem 288(47):34030-40 |
| abstractText | Many agonists, acting through G-protein-coupled receptors and Galpha subunits of the heterotrimeric G-proteins, induce contraction of smooth muscle through an increase of [Ca(2+)]i as well as activation of the RhoA/RhoA-activated kinase pathway that amplifies the contractile force, a phenomenon known as Ca(2+) sensitization. Galpha12/13 subunits are known to activate the regulator of G-protein signaling-like family of guanine nucleotide exchange factors (RhoGEFs), which includes PDZ-RhoGEF (PRG) and leukemia-associated RhoGEF (LARG). However, their contributions to Ca(2+)-sensitized force are not well understood. Using permeabilized blood vessels from PRG(-/-) mice and a new method to silence LARG in organ-cultured blood vessels, we show that both RhoGEFs are activated by the physiologically and pathophysiologically important thromboxane A2 and endothelin-1 receptors. The co-activation is the result of direct and independent activation of both RhoGEFs as well as their co-recruitment due to heterodimerization. The isolated recombinant C-terminal domain of PRG, which is responsible for heterodimerization with LARG, strongly inhibited Ca(2+)-sensitized force. We used photolysis of caged phenylephrine, caged guanosine 5'-O-(thiotriphosphate) (GTPgammaS) in solution, and caged GTPgammaS or caged GTP loaded on the RhoA.RhoGDI complex to show that the recruitment and activation of RhoGEFs is the cause of a significant time lag between the initial Ca(2+) transient and phasic force components and the onset of Ca(2+)-sensitized force. |
