"c-Src tyrosine kinase, a critical component for 5-HT2A receptor

ONG LU,; ABDERRAHMANE ALIOUA,; YOGESH KUMAR,; PALLOB KUNDU,; MANSOUREH EGHBALI,; NOELIA V. WEISSTAUB,; JAY A. GINGRICH,; ENRICO STEFANI,; LIGIA TORO

THE JOURNAL OF PHYSIOLOGY

Año: 2008

0022-3751

Serotonin (5-HT) receptors (5-HTRs) play critical roles in brain and cardiovascular functions. Inthe vasculature, 5-HT induces potent vasoconstrictions, which in aorta are mainly mediated byactivation of 5-HT2AR subtype. We previously proposed that one signaling mechanism of 5-HTinduced vasoconstriction could be c-Src, a member of the Src tyrosine kinase family. We nowprovide evidence for c-Src central role in 5-HT2AR mediated contraction. Inhibiting Src kinaseactivity with 10 μM PP2 prior contraction, resulted in ~90% to 99% inhibition of 5-HT or of α-methyl-5-HT (5-HT2R agonist)-induced contractions. In contrast, PP2-pretreatment only partiallyinhibited thromboxane A2 mimetic U46619- and angiotensin II-induced contractions, and had nosignificant action on phenylephrine-induced contractions. 5-HT increased Src kinase activity andPP2-sensitive tyrosine-phosphorylated proteins. As expected for c-Src identity, PP2 pretreatmentinhibited 5-HT-induced contraction with an IC50 of ~1 μM. Ketanserin (10 nM), a 5-HT2Aantagonist but not antagonists of 5-HT2BR (100 nM SB204741) or 5-HT2CR (20 nM RS102221)prevented 5-HT-induced contractions mimicking PP2 and pointing 5-HT2AR as the majorreceptor subtype coupled to c-Src. In HEK 293T cells, c-Src and 5-HT2AR were reciprocally coimmunoprecipitatedand colocalized at the cell periphery. Finally, 5-HT-induced Src activity wasunaffected by inhibition of Rho kinase, supporting a role of c-Src upstream Rho kinase. Togetherthe results highlight c-Src activation as one of the early and pivotal mechanisms in 5-HT2ARcontractile signaling in aorta.