Increased interaction of connexin43 with zonula occludens-1 during inhibition of gap junctions by G protein-coupled receptor agonists |
| |
Authors: | Tencé Martine Ezan Pascal Amigou Edwige Giaume Christian |
| |
Affiliation: | College de France, Center for Interdisciplinary Research in Biology (CIRB), CNRS UMR 7241, INSERM U1050, Paris, F-75005, France |
| |
Abstract: | Astrocytes are extensively coupled through gap junctions (GJs) that are composed of channels mostly constituted by connexin43 (Cx43). This astroglial gap junctional intercellular communication (GJIC) allows propagation of ions and signaling molecules critical for neuronal activity and survival. It is drastically inhibited by a short-term exposure to endothelin-1 (ET-1) or to sphingosine-1-phosphate (S1P), both compounds being inflammatory mediators acting through activation of GTP-binding protein-coupled receptors (GPCRs). Previously, we have identified the GTPases G(i/o) and Rho as key actors in the process of S1P-induced inhibition. Here, we asked whether similar mechanisms underlied the effects of ET-1 and S1P by investigating changes in the phosphorylation status of Cx43 and in the molecular associations of Cx43 with zonula occludens (ZO) proteins and occludin. We showed that the inhibitory effect of ET-1 on GJIC was entirely dependent on the activation of G(i/o) but not on Rho and Rho-associated kinase. Both ET-1 and S1P induced dephosphorylation of Cx43 located at GJs through a process mediated by G(i/o) and calcineurin. Thanks to co-immunoprecipitation approaches, we found that a population of Cx43 (likely junctional Cx43) was associated to ZO-1-ZO-2-occludin multiprotein complexes and that acute treatments of astrocytes with ET-1 or S1P induced a G(i/o)-dependent increase in the amount of Cx43 linked to these complexes. As a whole, this study identifies a new mechanism of GJIC regulation in which two GPCR agonists dynamically alter interactions of Cx43 with its molecular partners. |
| |
Keywords: | BSA, bovine serum albumin C, carboxyl Cx, connexin Cx43, connexin43 DG, deoxyglucose ET, endothelin ERK, extracellular signal-regulated kinase G, GTP-binding protein GJ, gap junction GJIC, gap junctional intercellular communication GPCR, GTP-binding protein coupled-receptor HRP, horse-radish peroxidase IgG, immunoglobulin G IP, immunoprecipitation LPA, lysophosphatidic acid MAPK, mitogen-activated protein kinase MTT, thiazolyl blue tetrazolium bromide PKC, protein kinase C PTX, pertussis toxin PP, phosphatase ROCK, Rho-associated kinase SDS-PAGE, sodium dodecylsulfate-polyacrylamide gel electrophoresis S1P, sphingosine-1-phosphate TRITC, tetramethylrhodamine isothiocyanate TBST, Tris-buffered saline/Tween TJ, tight junction ZO, zonula occludens |
本文献已被 ScienceDirect PubMed 等数据库收录! |
|