Human Connexin Channel Specificity of Classical and New Gap Junction Inhibitors

Abstract

Connexins are transmembrane proteins involved in gap junction intercellular communication. They present cell-and tissue-specific expression, with own electric and metabolic coupling specificities. These proteins are involved in numerous physiological processes in the brain and among them neuronal synchronization and trafficking of glucose. Such proteins are also described as being misregulated in various pathologies in the central nervous system. Thus, connexin blockers have been proposed as pharmacological tools to dissect these implications. However, such approaches lack accurate characterization of known inhibitors toward gap junction isoform specificity. In addition, those compounds are limited to few chemical classes and exhibit other activities, for example, an anti-inflammatory effect. The aims of this study were to evaluate the selectivity of described inhibitors and to enrich this pharmacopeia by new chemical classes. In this study, we present the specificity of published inhibitors toward several connexin isoforms expressed in the brain. Furthermore, after a screening of compounds using cellular models, we identified seven new inhibitors, with high functional reversibility and different relative selectivity toward isoforms. They constitute new chemical classes of connexin modulators completing those previously described. These new inhibitors might also provide new insights in understanding numerous pathophysiological processes involving gap junctions.

Potentiation of Amitriptyline Anti-Hyperalgesic-Like Action By Astroglial Connexin 43 Inhibition in Neuropathic Rats

“…After a 24 h exposure to mefloquine (MEFLO) at 0.5 μM, Cx43-mediated astrocyte coupling assessed from LY fluorescence spreading was significantly reduced (Fig. 1A,B; P  < 0.001, One-way ANOVA, Newman-Keuls test), as expected from GJC inhibition by this drug3031. Under the same conditions, amitriptyline (AMIT) was also found to inhibit Cx43-mediated astrocyte coupling in a concentration-dependent manner: by 22% (n = 4) at 5 μM, 27% (n = 5) at 10 μM, 58% (n = 4) at 20 μM (Fig.…”

“…Then, using the validated model of neuropathic pain that consists of unilateral ligation of the sciatic nerve in rats29, we explored whether partial Cx43 channels blockade by mefloquine, a potent connexin blocker3031, could interfere with the anti-hyperalgesic-like action of amitriptyline. Finally, whether pharmacokinetic and/or pharmacodynamic interactions accounted for the modulatory effect of mefloquine on amitriptyline-induced effect was investigated using relevant HPLC and real time RT-qPCR quantifications.…”

The Left-Right Pitx2 Pathway Drives Organ-Specific Arterial and Lymphatic Development in the Intestine

“…To uncouple arterial function from the Pitx2-driven Cxcr4/Cxcl12 axis we specifically blocked arteriogenesis with a validated Gja5 blocker, quinidine (Picoli et al, 2012). As expected, no Gja5 -positive 1°LA formed in quinidine-beaded embryos (HH24, Fig.…”

Neurochemical and electrical modulation of the locus coeruleus: contribution to CO2drive to breathe

“…Gap junctions are formed by proteins that create intercellular channels; these transmembrane pores facilitate the direct exchange of small molecules, metabolites, adenosine triphosphate (ATP) and ions between cells in direct contact (Hooper and Subak-Sharpe, 1981; Loewenstein, 1981; Picoli et al, 2012). These channels are composed by a combination of two hemichannels (connexons), each connexon containing a group of six proteins called connexins (Cx).…”

“…These channels are composed by a combination of two hemichannels (connexons), each connexon containing a group of six proteins called connexins (Cx). These proteins fold in a hexameric structure creating a hydrophilic channel that connects the cytosol of neighboring cells (Davidson and Baumgarten, 1988; Solomon and Dean, 2002; Picoli et al, 2012). …”