IMMUNOLOCALIZATION OF RETINOIC ACID RECEPTORS IN RAT, MOUSE AND HUMANOVARY AND UTERUS

We raised an antibody against a synthetic peptide corresponding to ami no acids 155-174 of human retinoic acid receptor alpha (RAR-alpha), Th e sequence is highly homologous in all RARs and their isoforms. When m ouse and human RARs (alpha, beta and gamma) expressed in Cos cell were analysed with immunoblot, all receptors gave a specific 51 K signal. Mouse RAR-gamma gave an additional signal corresponding to 58 K. In hu man teratocarcinoma cells (F9) both 51 and 58 K molecule sizes were de tected. The RAR expression in F9 cells was slightly down-regulated in charcoal-stripped culture medium and returned to normal level after re tinoic acid treatment. The 51 K protein was found in all ovarian and u terine samples, but the quantity of the 58 K protein varied in differe nt species and organs, being highest in the mouse uterus and the rat a nd human ovary. Using immunohistochemistry the RARs were found in the nuclear compartment. In the rat uterus, positive immunoreaction was fo und mainly in the nuclei of epithelial, uterine glandular and stromal cells. In the rat ovary, positive reaction was found in the nuclei of germinal epithelial, follicular and stromal cells.