Redistribution of connexin 43 by cAMP: a mechanism for growth control in adrenal cells.

In order to investigate the regulation of connexin distribution in rapidly growing cells, we evaluated the effects of dibutyryl cyclic adenosine monophosphate (DbcAMP) treatment on the cellular location of endogenous connexin 43 (Cx43) in an adrenal tumor cell population. Polyclonal antibodies to Cx43 and a Cx43 green fluorescent fusion protein (Cx43-GFP) were used to localize Cx43 gap junction protein in plaques at sites of cell-cell contact and in spherical packets within the cytoplasm. Treatment with DbcAMP significantly decreased the number and size of packets within the cytoplasm, and significantly increased surface gap junction plaque size. These data support the theory that cAMP can influence the availability of gap junction protein at the points of cell contact where it is required for cell-cell communication, and thus has the potential to be an important regulator of adrenal tumor cell proliferation.