Dataset Information

Inhibition of G?i activity by G?? is mediated by PI 3-kinase-?- and cSrc-dependent tyrosine phosphorylation of G?i and recruitment of RGS12.

ABSTRACT: Others and we have characterized several G??-dependent effectors in smooth muscle, including G protein-coupled receptor kinase 2 (GRK2), PLC?3, and phosphatidylinositol (PI) 3-kinase-?, and have identified various signaling targets downstream of PI 3-kinase-?, including cSrc, integrin-linked kinase, and Rac1-Cdc42/p21-activated kinase/p38 MAP kinase. This study identified a novel mechanism whereby G?? acting via PI 3-kinase-? and cSrc exerts an inhibitory influence on G?i activity. The Gi2-coupled ?-opioid receptor agonist d-penicillamine (2,5)-enkephalin (DPDPE) activated cSrc, stimulated tyrosine phosphorylation of G?i2, and induced regulator of G protein signaling 12 (RGS12) association; all three events were blocked by PI 3-kinase (LY294002) and cSrc (PP2) inhibitors and by expression of the COOH-terminal sequence of GRK2-(495-689), a G??-scavenging peptide. Inhibition of forskolin-stimulated cAMP and muscle relaxation by DPDPE was augmented by PP2, LY294002, and a selective PI 3-kinase-? inhibitor, AS-605420. Expression of tyrosine-deficient (Y69F, Y231F, or Y321F) G?i2 mutant or knockdown of RGS12 blocked G?i2 phosphorylation and G?i2-RGS12 association and caused greater inhibition of cAMP. Parallel studies using somatostatin, cyclopentyl adenosine, or ACh to activate, respectively, Gi1-coupled somatostatin (sstr3) receptors, and Gi3-coupled adenosine A1 or muscarinic m2 receptors elicited cSrc activation, G?i1 or G?i3 phosphorylation, G?i1-RGS12 or G?i3-RGS12 association, and inhibition of cAMP. Inhibition of cAMP and muscle relaxation was greatly increased by AS-605240 and PP2. The results demonstrate that G??-dependent tyrosine phosphorylation of G?i1/2/3 by cSrc facilitated recruitment of RGS12, a G?i-specific RGS protein with a unique phosphotyrosine-binding domain, resulting in rapid deactivation of G?i and facilitation of smooth muscle relaxation.

SUBMITTER: Huang J

PROVIDER: S-EPMC4010651 | biostudies-literature | 2014 May

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Inhibition of Gαi activity by Gβγ is mediated by PI 3-kinase-γ- and cSrc-dependent tyrosine phosphorylation of Gαi and recruitment of RGS12.

Huang Jiean J Nalli Ancy D AD Mahavadi Sunila S Kumar Divya P DP Murthy Karnam S KS

American journal of physiology. Gastrointestinal and liver physiology 20140227 9

Others and we have characterized several Gβγ-dependent effectors in smooth muscle, including G protein-coupled receptor kinase 2 (GRK2), PLCβ3, and phosphatidylinositol (PI) 3-kinase-γ, and have identified various signaling targets downstream of PI 3-kinase-γ, including cSrc, integrin-linked kinase, and Rac1-Cdc42/p21-activated kinase/p38 MAP kinase. This study identified a novel mechanism whereby Gβγ acting via PI 3-kinase-γ and cSrc exerts an inhibitory influence on Gαi activity. The Gi2-coupl ...[more]

PMID: 24578342

Similar Datasets

Project description:Bone homeostasis intimately relies on the balance between osteoblasts (OBs) and osteoclasts (OCs). Our previous studies have revealed that regulator of G protein signaling protein 12 (Rgs12), the largest protein in the Rgs super family, is essential for osteoclastogenesis from hematopoietic cells and OC precursors. However, how Rgs12 regulates OB differentiation and function is still unknown. To understand that, we generated an OB-targeted Rgs12 conditional knockout (CKO) mice model by crossing Rgs12fl/fl mice with Osterix (Osx)-Cre transgenic mice. We found that Rgs12 was highly expressed in both OB precursor cells (OPCs) and OBs of wild-type (WT) mice, and gradually increased during OB differentiation, whereas Rgs12-CKO mice (OsxCre/+ ; Rgs12fl/fl ) exhibited a dramatic decrease in both trabecular and cortical bone mass, with reduced numbers of OBs and increased apoptotic cell population. Loss of Rgs12 in OPCs in vitro significantly inhibited OB differentiation and the expression of OB marker genes, resulting in suppression of OB maturation and mineralization. Further mechanism study showed that deletion of Rgs12 in OPCs significantly inhibited guanosine triphosphatase (GTPase) activity and cyclic adenosine monophosphate (cAMP) level, and impaired Calcium (Ca2+ ) oscillations via restraints of major Ca2+ entry sources (extracellular Ca2+ influx and intracellular Ca2+ release from endoplasmic reticulum), partially contributed by the blockage of L-type Ca2+ channel mediated Ca2+ influx. Downstream mediator extracellular signal-related protein kinase (ERK) was found inactive in OBs of OsxCre/+ ; Rgs12fl/fl mice and in OPCs after Rgs12 deletion, whereas application of pertussis toxin (PTX) or overexpression of Rgs12 could rescue the defective OB differentiation via restoration of ERK phosphorylation. Our findings reveal that Rgs12 is an important regulator during osteogenesis and highlight Rgs12 as a potential therapeutic target for bone disorders. © 2018 American Society for Bone and Mineral Research.

Dataset Information

Inhibition of G?i activity by G?? is mediated by PI 3-kinase-?- and cSrc-dependent tyrosine phosphorylation of G?i and recruitment of RGS12.

Publications

Inhibition of Gαi activity by Gβγ is mediated by PI 3-kinase-γ- and cSrc-dependent tyrosine phosphorylation of Gαi and recruitment of RGS12.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets