RETINOIC ACID MODULATES GAP JUNCTIONAL PERMEABILITY - A COMPARATIVE-STUDY OF DYE SPREADING AND IONIC COUPLING IN CULTURED-CELLS

All-trans retinoic acid (RA), which was recently identified as a morphogen, affects gap junctional permeability in a dose- and time-dependent manner. In five different established mammalian cell lines (FL, BRL, BICR/M1Rk, HEL37, BT5C1) 100 μmol/liter RA reduced Lucifer yellow spreading within 30 min to 20-50% of the control. Ionic coupling, however, remained almost unaffected under the same conditions. Freezefractured membranes of untreated and RA-treated cells were similar with regard to frequency and sizes of gap junction plaques. With concentrations of less than 10 μmol/liter RA the dye spreading increased significantly in the human amniotic cell line FL, pointing to a possible modulatory effect of RA on junctional communication. © 1991.