scholarly journals Evidence of a common mechanism of disassembly of adherens junctions through Gα13 targeting of VE-cadherin

2014 ◽  
Vol 211 (3) ◽  
pp. 579-591 ◽  
Author(s):  
Haixia Gong ◽  
Xiaopei Gao ◽  
Shaoting Feng ◽  
M. Rizwan Siddiqui ◽  
Alexander Garcia ◽  
...  
Keyword(s):  
G Protein ◽  
Adherens Junctions ◽  
Common Mechanism ◽  
Binding Motif ◽  
P120 Catenin ◽  
Unique Role ◽  
Proinflammatory Mediators ◽  
The Stability ◽  
G Protein Coupled

The heterotrimeric G protein Gα13 transduces signals from G protein–coupled receptors (GPCRs) to induce cell spreading, differentiation, migration, and cell polarity. Here, we describe a novel GPCR-independent function of Gα13 in regulating the stability of endothelial cell adherens junctions (AJs). We observed that the oxidant H2O2, which is released in response to multiple proinflammatory mediators, induced the interaction of Gα13 with VE-cadherin. Gα13 binding to VE-cadherin in turn induced Src activation and VE-cadherin phosphorylation at Tyr 658, the p120-catenin binding site thought to be responsible for VE-cadherin internalization. Inhibition of Gα13–VE-cadherin interaction using an interfering peptide derived from the Gα13 binding motif on VE-cadherin abrogated the disruption of AJs in response to inflammatory mediators. These studies identify a unique role of Gα13 binding to VE-cadherin in mediating VE-cadherin internalization and endothelial barrier disruption and inflammation.

scholarly journals Distinct phosphorylation sites in a prototypical GPCR differently orchestrate β-arrestin interaction, trafficking, and signaling

2020 ◽  
Vol 6 (37) ◽  
pp. eabb8368 ◽  
Author(s):  
Hemlata Dwivedi-Agnihotri ◽  
Madhu Chaturvedi ◽  
Mithu Baidya ◽  
Tomasz Maciej Stepniewski ◽  
Shubhi Pandey ◽  
...  
Keyword(s):  
G Protein ◽  
Phosphorylation Site ◽  
Dynamics Simulation ◽  
Phosphorylation Sites ◽  
Functional Responses ◽  
Biased Signaling ◽  
The Stability ◽  
G Protein Coupled ◽  
Structural Aspects

Agonist-induced phosphorylation of G protein–coupled receptors (GPCRs) is a key determinant for their interaction with β-arrestins (βarrs) and subsequent functional responses. Therefore, it is important to decipher the contribution and interplay of different receptor phosphorylation sites in governing βarr interaction and functional outcomes. Here, we find that several phosphorylation sites in the human vasopressin receptor (V2R), positioned either individually or in clusters, differentially contribute to βarr recruitment, trafficking, and ERK1/2 activation. Even a single phosphorylation site in V2R, suitably positioned to cross-talk with a key residue in βarrs, has a decisive contribution in βarr recruitment, and its mutation results in strong G-protein bias. Molecular dynamics simulation provides mechanistic insights into the pivotal role of this key phosphorylation site in governing the stability of βarr interaction and regulating the interdomain rotation in βarrs. Our findings uncover important structural aspects to better understand the framework of GPCR-βarr interaction and biased signaling.

scholarly journals The Role of G Protein-Coupled Receptors in the Right Ventricle in Pulmonary Hypertension

2018 ◽  
Vol 5 ◽  
Author(s):  
Gayathri Viswanathan ◽  
Argen Mamazhakypov ◽  
Ralph T. Schermuly ◽  
Sudarshan Rajagopal
Keyword(s):  
Pulmonary Hypertension ◽  
Right Ventricle ◽  
G Protein ◽  
G Protein Coupled Receptors ◽  
The Right ◽  
G Protein Coupled

Sustained muscle contraction induced by agonists, growth factors, and Ca2+ mediated by distinct PKC isozymes

2000 ◽  
Vol 279 (1) ◽  
pp. G201-G210 ◽  
Author(s):  
K. S. Murthy ◽  
J. R. Grider ◽  
J. F. Kuemmerle ◽  
G. M. Makhlouf
Keyword(s):  
Growth Factors ◽  
G Protein ◽  
Muscle Cells ◽  
Sustained Contraction ◽  
Calphostin C ◽  
Epidermal Growth ◽  
Pkc Isozymes ◽  
G Protein Coupled ◽  
Pkc Activation

The role of protein kinase C (PKC) in sustained contraction was examined in intestinal circular and longitudinal muscle cells. Initial contraction induced by agonists (CCK-8 and neuromedin C) was abolished by 1) inhibitors of Ca2+ mobilization (neomycin and dimethyleicosadienoic acid), 2) calmidazolium, and 3) myosin light chain (MLC) kinase (MLCK) inhibitor KT-5926. In contrast, sustained contraction was not affected by these inhibitors but was abolished by 1) the PKC inhibitors chelerythrine and calphostin C, 2) PKC-ε antibody, and 3) a pseudosubstrate PKC-ε inhibitor. GDPβS abolished both initial and sustained contraction, whereas a Gαq/11 antibody inhibited only initial contraction, implying that sustained contraction was dependent on activation of a distinct G protein. Sustained contraction induced by epidermal growth factor was inhibited by calphostin C, PKC-α,β,γ antibody, and a pseudosubstrate PKC-α inhibitor. Ca2+ (0.4 μM) induced an initial contraction in permeabilized muscle cells that was blocked by calmodulin and MLCK inhibitors and a sustained contraction that was blocked by calphostin C and a PKC-α,β,γ antibody. Thus initial contraction induced by Ca2+, agonists, and growth factors is mediated by MLCK, whereas sustained contraction is mediated by specific Ca2+-dependent and -independent PKC isozymes. G protein-coupled receptors are linked to PKC activation via distinct G proteins.

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