ギャップ結合とタイト結合との関連

抄録

It is thought that gap junctions may be closely associated with tight junctions. However, the mechanisms are still undefined. We found that Cx32 but not Cx26 was closely related to tight junctional proteins in primary cultured rat hepatocytes (Exp. Cell Res. 263, 193-201, 2001) and that Cx32 formation and/or Cx32-mediated intercellular communication could induce expression and function of tight junctions in a mouse hepatic cell line (Exp. Cell Res. 276, 40-51, 2002). When we performed cDNA microarray analysis of Cx32-transfectants, compared to parental cells derived from Cx32-deficient hepatocytes, an increase in expression of membrane-associated guanylate kinase with inverted orientation -1 (MAGI-1), which is known to be localized at adherens and tight junction regions, was observed (Cell Tissue Res. 319, 341-347, 2005). More recently, we performed to express short interfering RNA (siRNA) for Cx32 in primary cultured rat hepatocytes which highly expressed Cx32 and tight junction proteins and examined changes in expression of tight junction proteins and activated MAP-kinase. Down-regulation of Cx32 was associated with a decrease of claudin-1 and an increase of claudin-2. Furthermore, up-regulation of phosphorylated MAP-kinase was observed by the siRNA. Cx32 expression may in part regulate expression of tight junctions through the signal transduction pathway such as MAP-kinase. [J Physiol Sci. 2006;56 Suppl:S28]