Developmental mRNA Expression of Cellular Retinoic Acid Binding Protein l and l in Rat

ABSTRACT

PURPOSE: Retinoic acid (RA) is well known as a potent teratogenic agent in both deficiency and excess. Cellular retinoic acid binding proteins (CRABPs) are involved in RA. We carried this study in order to determine the possible relations of CRABPs with RA-induced teratogenesis through observation of the expression patterns of CRABP l and ll in developing rats. METHODS: 35S-labeled RNA probes were synthesized using SP6-RNA polymerase in CRABP l and T7-polymerase in CRABP ll. The distribution of CRABP l and ll transcripts analyzed by in situ hybridization of rat embryosections from day 12 to 19, and postnatal brains from day 1 to 14. RESULTS: The CRABP ll transcripts were more widely distributed than CRABPl distribution, however, the relative level of CRABPl transcripts were higher than CRABP ll. The CRABP l mRNA transcripts showed its highest expression on the 16th day of gestation and these distribution correlated well with structures known to be targets of RA-induced teratogenesis. CRABP ll transcripts were expressed in brain vesicle, spinal cord, head, face, tongue and genital tubercle and also found in the structures which are not involved in RA-induced teratogenesis. CONCLUSION: These results suggest the possible involvement of both CRABPs in the RA-induced teratogenesis. However, CRABP l may have more specific roles than CRABP ll which may play a role through a different mechanism.