Shear stress induces G?q/11 activation independently of G protein-coupled receptor activation in endothelial cells.
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ABSTRACT: Mechanochemical signal transduction occurs when mechanical forces, such as fluid shear stress, are converted into biochemical responses within the cell. The molecular mechanisms by which endothelial cells (ECs) sense/transduce shear stress into biological signals, including the nature of the mechanosensor, are still unclear. G proteins and G protein-coupled receptors (GPCRs) have been postulated independently to mediate mechanotransduction. In this study, we used in situ proximity ligation assay (PLA) to investigate the role of a specific GPCR/G?q/11 pair in EC shear stress-induced mechanotransduction. We demonstrated that sphingosine 1-phosphate (S1P) stimulation causes a rapid dissociation at 0.5 min of G?q/11 from its receptor S1P3, followed by an increased association within 2 min of GPCR kinase-2 (GRK2) and ?-arrestin-1/2 with S1P3 in human coronary artery ECs, which are consistent with GPCR/G?q/11 activation and receptor desensitization/internalization. The G protein activator AlF4 resulted in increased dissociation of G?q/11 from S1P3, but no increase in association between S1P3 and either GRK2 or ?-arrestin-1/2. The G protein inhibitor guanosine 5'-(?-thio) diphosphate (GDP-?-S) and the S1P3 antagonist VPC23019 both prevented S1P-induced activation. Shear stress also caused the rapid activation within 7 s of S1P3/G?q/11 There were no increased associations between S1P3 and GRK2 or S1P3 and ?-arrestin-1/2 until 5 min. GDP-?-S, but not VPC23019, prevented dissociation of G?q/11 from S1P3 in response to shear stress. Shear stress did not induce rapid dephosphorylation of ?-arrestin-1 or rapid internalization of S1P3, indicating no GPCR activation. These findings suggest that G?q/11 participates in the sensing/transducing of shear stress independently of GPCR activation in ECs.
SUBMITTER: Dela Paz NG
PROVIDER: S-EPMC5407018 | biostudies-literature | 2017 Apr
REPOSITORIES: biostudies-literature
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