EXPRESSION OF P53 IN NORMAL AND GAMMA-IRRADIATED RAT TESTIS SUGGESTS A ROLE FOR P53 IN MEIOTIC RECOMBINATION AND REPAIR

In testis, the expression of tumor suppressor protein p53 is stronger than in other tissues suggesting a role for it in spermatogenesis. We have studied the expression of p53 in both unirradiated and gamma-irra diated rat testis using the stage-specific model of rat seminiferous e pithelium, Our results show that p53 is expressed during meiosis in no rmal rat spermatogenesis and its expression is localized to the prelep totene-early pachytene spermatocytes. The most prominent expression is in zygotene - early pachytene spermatocytes (stages XIII-I of seminif erous epithelium). After irradiation p53 levels increased in a time an d a dose-dependent manner being highest with the doses of 6.0 and 12.0 Gy and 4 h after irradiation, This increase occurs in the same cells that normally express elevated levels of p53. These results support th e view that p53 is involved in meiosis of the male rat and we suggest that p53 has a role in recombinational processes and/or formation of t he synaptonemal complex. We also demonstrate that p53 takes part in th e response of primary spermatocytes to gamma-irradiation induced DNA d amage.