P53 IS ASSOCIATED WITH THE NUCLEAR-ENVELOPE IN MOUSE TESTIS

p53 has been postulated to play a role in meiosis as well as in the re gulation of germ cell numbers by apoptosis. This study investigated th e subcellular localization of p53 in the testis, including conditions known to induce germ cell apoptosis. Western blot analysis showed that p53 was enriched in the nuclear envelope fraction, and confocal micro scopy confirmed that p53 was associated with the nuclear envelope of g erm cells. Exposure of the testis to heat stress induced translocation of p53 into the nucleus. Nuclear envelope binding provides an optimal site for rapid entry of p53 into the nucleus, where it may act as a D NA-binding protein to induce apoptosis or cell cycle arrest in respons e to appropriate stimuli. The nuclear envelope sequestration of p53 al so provides a framework to understand how mitosis and meiosis in the t estis may proceed despite high intracellular concentration of p53. (C) 1997 Academic Press.