Connexin 30.2 is expressed in mouse pancreatic beta cells.

Nowadays, connexin (Cx) 36 is considered the sole gap junction protein expressed in pancreatic beta cells. In the present research we investigated the expression of Cx30.2 mRNA and protein in mouse pancreatic islets. Cx30.2 mRNA and protein were identified in isolated islet preparations by qRT-PCR and Western blot, respectively. Immunohistochemical analysis showed that insulin-positive cells were stained for Cx30.2. Confocal images from double-labeled pancreatic sections revealed that Cx30.2 and Cx36 fluorescence co-localize at junctional membranes in islets from most pancreases. Abundant Cx30.2 tiny reactive spots were also found in cell cytoplasms. In beta cells cultured with stimulatory glucose concentrations, Cx30.2 was localized in both cytoplasms and cell membranes. In addition, Cx30.2 reactivity was localized at junctional membranes of endothelial or cluster of differentiation 31 (CD31) positive cells. Moreover, a significant reduction of Cx30.2 mRNA was found in islets preparations incubated for 24h in 22mM as compared with 3.3mM glucose. Therefore, it is concluded that Cx30.2 is expressed in beta and vascular endothelial cells of mouse pancreatic islets.