Differentiating the effects of Cx36 and E-cadherin for proper insulin secretion of MIN6 cells

Exp Cell Res. 2004 Apr 1;294(2):379-91. doi: 10.1016/j.yexcr.2003.12.007.

Abstract

Connexins have been implicated in many cell functions, even though in most cases it is still unclear whether these functions may actually be mediated by other proteins that are secondarily affected by connexin changes. Secretory systems provide useful models in which to tackle this central question. Primary pancreatic beta-cells and insulin-producing lines are connected by gap junction channels made of Cx36. Using stable transfection of an antisense Cx36 cDNA, we have previously obtained clones of MIN6 cells that featured a markedly reduced expression of Cx36 and impaired insulin secretion. Here, we first show that this change also resulted in loss of E-cadherin and occludin expression, thus preventing the attribution of the secretory defects to a specific type of membrane protein. To investigate this question, we have now restored the expression of either Cx36 or E-cadherin in the Cx36 antisense-transfected cells. We show that a lentivirus-mediated transduction efficiently restored Cx36 expression in MIN6 cells and allowed for expression of variable levels of this protein. We further document that adequate but not excessive levels of Cx36 allowed for recover of normal insulin secretion in response to various secretagogues. Finally, we demonstrate that restoration of normal E-cadherin expression was not able to achieve the same secretory correction. The data demonstrate that Cx36, but not E-cadherin, is necessary to control specific steps of beta-cell secretion.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Cadherins / genetics
  • Cadherins / metabolism*
  • Cell Adhesion / genetics
  • Cell Communication / genetics
  • Cell Line, Tumor
  • Connexins / genetics
  • Connexins / metabolism*
  • DNA, Antisense / genetics
  • Dogs
  • Down-Regulation / genetics
  • Gap Junctions / genetics
  • Gap Junctions / metabolism*
  • Gap Junctions / ultrastructure
  • Gene Expression Regulation / genetics
  • Insulin / metabolism*
  • Insulin Secretion
  • Islets of Langerhans / metabolism*
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism
  • Membrane Proteins / ultrastructure
  • Mice
  • Microscopy, Electron, Scanning
  • Occludin
  • Tight Junctions / genetics
  • Tight Junctions / metabolism
  • Transfection

Substances

  • Cadherins
  • Connexins
  • DNA, Antisense
  • Insulin
  • Membrane Proteins
  • Occludin
  • Ocln protein, mouse
  • connexin 36