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Shear stress induces G?q/11 activation independently of G protein-coupled receptor activation in endothelial cells.

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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Shear stress induces Gα<sub>q/11</sub> activation independently of G protein-coupled receptor activation in endothelial cells.

Dela Paz Nathaniel G NG Melchior Benoît B Frangos John A JA

American journal of physiology. Cell physiology 20170201 4

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 ...[more]

PMID: 28148497

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Project description:Background & aimsProliferation, differentiation, and morphogenesis of the intestinal epithelium are tightly regulated by a number of molecular pathways. Coordinated action of intestine is achieved by gastrointestinal hormones, most of which exert these actions through G-protein-coupled receptors. We herein investigated the role of Gαq/11-mediated signaling in intestinal homeostasis.MethodsIntestinal tissues from control (Gnaqflox/floxGna11+/+ ), Int-Gq knock-out (KO) (VilCre+/-Gnaqflox/floxGna11+/+ ), G11 KO (Gnaqflox/floxGna11-/- ), and Int-Gq/G11 double knock-out (DKO) (VilCre+/-Gnaqflox/floxGna11-/- ) mice were examined by microscopy, transmission electron microscopy, and immunohistochemistry. The effect of Gαq/11-mediated signaling was studied in the cell lineage, proliferation, and apoptosis. Dextran sodium sulfate (DSS) colitis was induced to study the role of Gαq/11 in colon.ResultsPaneth cells were enlarged, increased in number, and mislocalized in Int-Gq/G11 DKO small intestine. Paneth cells also reacted with PAS and Muc2 antibody, indicating an intermediate character of Paneth and goblet cells. The nuclear β-catenin, T-cell factor 1, and Sox9 expression were reduced severely in the crypt base of Int-Gq/G11 DKO intestine. Proliferation was activated in the crypt base and apoptosis was enhanced along the crypt. Int-Gq/G11 DKO mice were susceptible to DSS colitis. Proliferation was inhibited in the crypt of unaffected and regenerative areas. Cystic crypts, periodic acid-Schiff-positive cells, and Muc2-positive cells were unusually observed in the ulcerative region.ConclusionsThe Gαq/11-mediated pathway plays a pivotal role in the preservation of intestinal homeostasis, especially in Paneth cell maturation and positioning. Wnt/β-catenin signaling was reduced significantly in the crypt base in Gαq/G11-deficient mice, resulting in the defective maturation of Paneth cells, induction of differentiation toward goblet cells, and susceptibility to DSS colitis.

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Dataset Information

Shear stress induces G?q/11 activation independently of G protein-coupled receptor activation in endothelial cells.

Publications

Shear stress induces Gα<sub>q/11</sub> activation independently of G protein-coupled receptor activation in endothelial cells.

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