INDUCTION OF GAP JUNCTIONAL COMMUNICATION BY 4-OXORETINOIC ACID GENERATED FROM ITS PRECURSOR CANTHAXANTHIN

The activity of 4-oxoretinoic acid as an inducer of gap junctional com munication was investigated in C3H/10T1/2 murine fibroblasts. Two isom ers of this retinoid, all-trans- and 13-cis-4-oxoretinoic acid, enhanc e gap junctional communication. This is accompanied by increased expre ssion of connexin43 mRNA. Decomposition fractions of canthaxanthin wer e isolated by preparative high-performance liquid chromatography and s hown to be active in the cell-cell communication assay. Two of the dec omposition compounds were identified as all-trans- and 13-cis-4-oxoret inoic acid. Therefore, it is concluded that the biological activity of canthaxanthin regarding cell-cell communication is at least in part d ue to the formation of active decomposition products such as 4-oxoreti noic acid. (C) 1995 Academic Press, Inc.