Acute loss of Cell–Cell Communication Caused by G Protein–coupled Receptors: A Critical Role for c-Src

Abstract

Gap junctions mediate cell–cell communication in almost all tissues, but little is known about their regulation by physiological stimuli. Using a novel single-electrode technique, together with dye coupling studies, we show that in cells expressing gap junction protein connexin43, cell–cell communication is rapidly disrupted by G protein–coupled receptor agonists, notably lysophosphatidic acid, thrombin, and neuropeptides. In the continuous presence of agonist, junctional communication fully recovers within 1–2 h of receptor stimulation. In contrast, a desensitization-defective G protein–coupled receptor mediates prolonged uncoupling, indicating that recovery of communication is controlled, at least in part, by receptor desensitization. Agonist-induced gap junction closure consistently follows inositol lipid breakdown and membrane depolarization and coincides with Rho-mediated cytoskeletal remodeling. However, we find that gap junction closure is independent of Ca2+, protein kinase C, mitogen-activated protein kinase, or membrane potential, and requires neither Rho nor Ras activation. Gap junction closure is prevented by tyrphostins, by dominant-negative c-Src, and in Src-deficient cells. Thus, G protein–coupled receptors use a Src tyrosine kinase pathway to transiently inhibit connexin43-based cell–cell communication.

The effects of connexin phosphorylation on gap junctional communication

“…The c-Src tyrosine kinase has been implicated in the ability of G protein-coupled receptors to induce the disruption of Cx43-mediated gap junctional communication (Postma et al, 1998). In this work, downstream signaling initiated by G protein-coupled receptors activated by lysophosphatidic acid and thrombin were independent of Ca 2+ mobilization and the activation of PKC, MAP kinase, Rho, or Ras.…”

Inhibition of the production of endothelium‐derived hyperpolarizing factor by cannabinoid receptor agonists

“…Anandamide has been reported to inhibit gap junction conductance and dye permeability in astrocytes in a pertussis toxin-sensitive manner (Venance et al, 1995;Schmilinsky-Fluri et al, 1997). Moreover, cell-cell communication in connexin 43-expressing cells is rapidly and transiently disturbed by G protein-coupled receptors (Postma et al, 1998) via a process involving the activation of p60 Src . Other indications that CB1 agonists interfere with gap junction conductance can be indirectly inferred from observations that MAP kinases are involved in the regulation of connexin 43-based cell-cell communication (Kanemitsu & Lau, 1993) and that anandamide (Wartmann et al, 1995) and HU 210 (authors unpublished observations) can activate MAP kinase in cells expressing the CB1 receptor.…”

β-arrestin2 mediates β-2 adrenergic receptor signaling inducing prostate cancer cell progression

“…It was the first identified and the essential protein tyrosine kinase (34,35), which could modulate various cellular functions including proliferation, survival, adhesion, and migration (33). Many GPCRs are able to stimulate tyrosine phosphorylation, increase Src family tyrosine kinases activity (36)(37)(38)(39). c-Src could switch β2AR from adenylyl cyclase coupling to Ras activation and its downstream effectors, MAPK pathway (40,41).…”