Retinoic acid inhibits junctional communication between animal cells

Retinoic acid inhibits junctional communication between a varietyof vertebrate cell types in culture. It reduces the intercellulartransfer of ³H-nucleotides between Syrian hamster kidney fibroblasts(BHK 21/13), Chinese hamster lung fibro-blasts (V79), rat liverepithelial cells (BRL), Swiss mouse embryo fibroblasts (3T3),rainbow trout gonadal fibroblasts (RTG2) and Xenopus embryofibroblasts (Xen). It also reduces metabolic cooperation betweenhypoxanthine-guanine phosphoribosyl transferase deficient mutantand wild-type BHK cells. The inhibition is rapid (intercellulartransfer of iontophoretically injected Lucifer Yellow CH betweenBRL cells is completely blocked after the cells have been exposedto 10^–4 M retinoic acid for 5 min), and is fully reversedwhen the drug is removed. Based on these results and the observationthat the amount of gap junctional protein isolated from cellsgrown in the presence of retinoic acid for 1 h is the same andafter 24 h is increased (1.3- to 3.1-fold) compared with theamount isolated from untreated cells, we suggest that the inhibitoryeffect is mediated by the reversible closure of junctional channels.