Convergent NMDA receptor—Pannexin1 signaling pathways regulate the interaction of CaMKII with Connexin-36

Abstract

Ca2+/calmodulin-dependent protein kinase II (CaMKII) binding and phosphorylation of mammalian connexin-36 (Cx36) potentiate electrical coupling. To explain the molecular mechanism of how Cx36 modifies plasticity at gap junctions, we investigated the roles of ionotropic N-methyl-D-aspartate receptors and pannexin1 (Panx1) channels in regulating Cx36 binding to CaMKII. Pharmacological interference and site-directed mutagenesis of protein interaction sites shows that NMDA receptor activation opens Cx36 channels, causing the Cx36- CaMKII binding complex to adopt a compact conformation. Ectopic Panx1 expression in a Panx1 knock-down cell line is required to restore CaMKII mediated opening of Cx36. Furthermore, blocking of Src-family kinase activation of Panx1 is sufficient to prevent the opening of Cx36 channels. Our research demonstrates that the efficacy of Cx36 channels requires convergent calcium-dependent signaling processes in which activation of ionotropic N-methyl-D-aspartate receptor, Src-family kinase, and Pannexin1 open Cx36. Our results add to the best of our knowledge a new twist to mounting evidence for molecular communication between these core components of electrical and chemical synapses.

ER-resident STIM1/2 couples Ca 2+ entry by NMDA receptors to pannexin-1 activation

“…Alternatively, each mechanism may be favored by activation of NMDARs having distinct GluN2 subunit composition (e.g., GluN2A vs. GluN2B). More recently, Panx1 activation in response to NMDAR stimulation has been implicated in crosstalk between glutamatergic and electrical transmission via gap junctions ( 55 ). Collectively, this suggests an important role of Panx1 as a connecting point and downstream effector of NMDAR-mediated physiological and pathological functions.…”

Asymmetric Dimethylarginine Protects Neurons from Oxygen Glucose Deprivation Insult by Modulating Connexin-36 Expression

“…We did not know the mechanism underlying the effect of ADMA on cx-36 expression in this work. According to previous studies, the potential regulator of cx-36 expression or function included CaMKII pathway [ 45 ], group II metabotropic glutamate receptors (mGluRs) pathway, and cAMP-dependent protein kinase-dependent signaling pathway [ 40 ]. However, we have no idea whether these pathways are also involved in the regulation of ADMA on cx-36, and we also do not know if there is any other pathway.…”

Panx1 Ablation Aggravates Oxidative Stress and Cell Death by Altering AMPK/mTOR signaling Pathways and the Composition of Synapses in the Zebrafish

“…Panx1 channel blockage with the mimetic peptide 10 Panx1 increases the synaptic level of endocannabinoids (eCB) and the activation of cannabinoid receptors type 1 (CB1Rs), decreasing hippocampal GABAergic efficacy and shifting excitation/inhibition (E/I) balance toward excitation and facilitating the induction of long-term potentiation 73 . Further, we have reported a pathway that connects NMDA receptor signaling to the opening of electrical synapse protein Cx36 via Panx1 and CaMK2a, suggesting active participation of Panx1 in modulating both chemical and electrical synapse function by using a shared molecular machinery 74 .…”

“…Collectively, these studies demonstrate a regulatory role for Panx1 in modulating balance toward excitation and facilitating the induction of long-term potentiation 73 . Further, we have reported a pathway that connects NMDA receptor signaling to the opening of electrical synapse protein Cx36 via Panx1 and CaMK2a, suggesting active participation of Panx1 in modulating both chemical and electrical synapse function by using a shared molecular machinery 74 .…”