Expression localization of Bmi1 in mice testis.

B cell-specific Moloney murine leukaemia virus integration site 1 (Bmi1), known as the first functional member of PcG (Polycomb Group) family, is supposed to be a key regulator of stem cell self-proliferation. In this study, we investigated its expression in testis and its impact on spermatogonia proliferation for better understanding of its role in spermatogenesis. Results showed that Bmi1 was expressed in undifferentiated spermatogonia (A(s), A(pr) and A(al) spermatogonia). Overexpression of BMI1 could promote spermatogonia proliferation, while repression of endogenous Bmi1 by RNAi resulted in inhibition of the proliferation.