Rapid, non-genomic vascular actions of genistein involves a G-protein coupled receptor

Abstract

Background: Genistein enhances endothelial function in a receptor-mediated manner. The present studies were designed to identify the putative receptor and related signaling pathways in the rapid vascular actions of genistein. Methods: Isometric tension was measured in isolated aortic rings from 32-weeksROGPDOHVSRQWDQHRXVO\K\SHUWHQVLYH UDWV (VWURJHQ UHFHSWRU Į HVWURJHQ UHFHSWRU Į HVWURJHQ UHFHSWRU Į DQG* SURWHLQ FRXSOHG UHFHSWRU LGHQWLILHG DVWKH SRWHQWLDO candidates of the putative receptor, were cloned and expressed using a cell-free expression system (MembraneMax Protein Expression Kit). Results: Genistein acutely potentiated acetylcholine-induced relaxation. This effect was insensitive to the transcription and translation inhibitors, actinomycin D and cycloheximide respectively. The potentiation of acetylcholine and A23187-induced relaxation by genistein ZDVLQKLELWHG E\1) DQG*3 DQWDJRQLVW $ WKH VHOHFWLYH*i/o and Gq Į VXEXQLW DQWDJRQLVWV UHVSHFWLYHO\ EXWQRWE\1) DVHOHFWLYH*sĮ VXEXQLWDQWDJRQLVW ,QRUGHU to identify the putative receptors, the cDNA of candidates were successfully amplified IURP0&) FHOOXVLQJ3&5DQGIXUWKHUFORQHGLQWRWKHH[SUHVVLRQYHFWRU S(;3 17 7232 ZKLFKZDVFRQ¿UPHGE\VHTXHQFLQJ 6ROXEOHUHFHSWRUSURWHLQVZHUHH[SUHVVHGin vitro ZKRVHPROHFXODUVL]HVZHUHFRQ¿UPHGE\:HVWHUQEORWWLQJDQGSXUL¿HG IRUXVHLQ radioligand binding assay. Conclusion: Our results demonstrate that rapid effect of genistein in potentiating UHOD[DWLRQLVQRQ JHQRPLFDQG*Įi DQG*Įq EXWQRW*Įs, were involved in the effect of genistein in potentiating acetylcholine and A23187-induced relaxations. Involvement of G-proteins suggests that genistein exerts its effect through a putative G-protein coupled receptor. Radioligand binding assays will be performed to confirm the identity of this putative receptor.