Contents lists available at ScienceDirect Acta Histochemica journal homepage: www.elsevier.com/locate/acthis Connexin 30.2 is expressed in exocrine vascular endothelial and ductal epithelial cells throughout pancreatic postnatal development C. Coronel-Cruz a , I. Sánchez a , B. Hernández-Tellez a , V. Rodríguez-Mata a , E. Pinzón-Estrada b , A. Castell-Rodríguez a , E.M. Pérez-Armendariz a,c, ⁎ a Departamento de Biología Celular y Tisular, Facultad de Medicina, Universidad Nacional Autónoma de México, Av. Universidad 3000, circuito interior, s/n, Ciudad Universitaria, CDMX, C.P., 04510, México b Bioterio, Facultad de Medicina, Universidad Nacional Autónoma de México, Av. Universidad 3000, circuito interior, s/n, Ciudad Universitaria, CDMX, C.P., 04510, México c Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Av. Universidad 3000, circuito interior, s/n, Ciudad Universitaria, CDMX, C.P., 04510, México ARTICLE INFO Keywords: Connexin 30.2 Endothelial and smooth muscle vascular cells Epithelial ductal cells Gap junctions Exocrine pancreas ABSTRACT Previously we have demonstrated that the GJ protein connexin 30.2 (Cx30.2) is expressed in pancreatic beta cells and endothelial cells (ECs) of the islet. In the present study, we address whether Cx30.2 is expressed in the exocrine pancreas, including its vascular system. For this, adult mouse pancreatic sections were double labeled with specific antibodies against Cx30.2 and CD31, an endothelial cell marker, or with anti-α-actin smooth muscle, a smooth muscle cell (SMC) marker or anti-mucin-1, a marker of epithelial ductal cells, using im- munofluorescence (IF) studies. Cx30.2-IF hot spots were found at junctional membranes of exocrine ECs and SMCs of blood vessels. Furthermore, Cx30.2 was localized in mucin-1 positive cells or epithelial ductal cells. Using immunohistochemistry (IHC) studies, it was found that in vessels and ducts of different diameters, Cx30.2 was also expressed in these cell types. In addition, it was found that Cx30.2 is already expressed in these cell types in pancreatic sections of 3, 14 and 21 days postpartum. Moreover, this cell specific pattern of expression was also found in the adult rat, hamster and guinea pig pancreas. Expression of Cx30.2 mRNA and protein in the pancreas of all these species was confirmed by RT-PCR and Western blot studies. Overall, our results suggest that intercellular coupling mediated by Cx30.2 intercellular channels may synchronize the functional activity of ECs and SMCs of vascular cells, as well as of epithelial ductal cells after birth. 1. Introduction Gap junctions (GJ) are conglomerates of intercellular channels, which allow the direct transfer of ions and second messengers between neighboring cells. In vertebrates, the intercellular channels are mainly formed by the connexin (Cx) protein family. The connexins (Cxs) be- long to a family of homologous transmembrane proteins formed by 20 genes in the mouse and 21 in humans. Cx proteins have a specific cell distribution (Willecke et al., 2002). Each hemichannel is formed by six subunits of one or more Cx subtype (s) (Saez et al., 2010). Two hemi- channels form an intercellular channel. Functional properties of chan- nels and hemichannels depend on their molecular composition (Verselis and Srinivas, 2013). It has been shown that the Cx family of proteins is critical for cell function and tissue development (see below) as well as being involved in human pathology (Dobrowolski and Willecke, 2009; Saez et al., 2003; Wei et al., 2004). In the vascular system, locally, both endothelial cells (ECs) and peri- vascular or mural contractile cells, including smooth muscle cells (SMCs) and pericytes, contribute to the modulation of vasomotor tone (Schmidt et al., 2008). All blood vessels have an internal tunic formed by a monolayer of ECs (Richards et al., 2010). This layer is surrounded by a medium tunic that includes one or more layers of SMCs distributed helically and perpendicular to the ECs (Brisset et al., 2009). It is well known that vascular cells communicate through inter- cellular channels. GJ have been found in ECs of the rat basilar artery by ultrastructural studies (Haddock et al., 2006). Furthermore, inter- cellular transfer of DAPI between ECs from rat retina capillaries was found using the scrape loading technique (Manasson et al., 2013). In addition, in the isolated descending vasa recta vessels of the rat kidney medulla, Lucifer Yellow (LY) microinjected into one of the ECs transfers https://doi.org/10.1016/j.acthis.2018.06.007 Received 23 January 2018; Received in revised form 10 June 2018; Accepted 29 June 2018 ⁎ Corresponding author at: Laboratorio de sinapsis eléctricas, Departamento de Biología Celular y Tisular and Departamento de Fisiología, Torre de Investigación, 6to piso, Facultad de Medicina, Universidad Nacional Autónoma de México, Av. Universidad 3000, Ciudad Universitaria, CDMX, C.P., 04510, México. E-mail address: emperezarmendariz@comunidad.unam.mx (E.M. Pérez-Armendariz). Acta Histochemica 120 (2018) 558–565 0065-1281/ © 2018 Elsevier GmbH. All rights reserved. T