Immunocytochemical localization of connexin 43 and E-cadherin in I-407 cells mediated by cAMP

The formation of gap junction and the expression of E-cadherin were studied by immunocytochemistry in a cultured intestinal-407 (I-407) cell colonies. These cells scarcely expressed connexin 43 (Cx43) and E-cadherin at a non- stimulated condition. When the cells were stimulated with forskolin and Ro- 20-1724, a strong correlation was found between immunocytochemical staining of E-cadherin and that of Cx43 at cell-to-cell contact areas. The length o f E-cadherin-positive contact areas increased with time in the stimulated c ondition. On the other hand, the number of gap junctional plaques in the E- cadherin-expressed areas increased significantly 2 to 8 hr after the stimul ation and remained the same level until 24 hr. Both immunostainings were mo re intense in the central area of the colony than in the peripheral area. S ince the administration of forskolin and Ro-20-1724 has been known to eleva te cAMP level, these results suggest that (1) the expression of both E-cadh erin and gap junctions in cell-to-cell contact is induced by the elevation of cAMP and (2) the effect of cAMP varies by the location of cells in the c olony which may reflect the state of cell differentiation.