Developmental regulation of the bcl-2 family during spermatogenesis: Insights into the sterility of bcl-w-/- male mice

Expression of bcl-w, a close relative of bcl-2 is essential for male fertil ity in mice. Although the initial wave of spermatogenesis in bcl-w-/- mice proceeds normally until 3-4 weeks of age, adults fail to produce sperm. To clarify why bcl-w is essential for adult but not juvenile spermatogenesis, we investigated the expression pattern of eight bcl-2 family members. We fo und that both the level and pattern of expression varied in different cell types during juvenile and adult spermatogenesis, Anti-apoptotic genes bcl-w , bcl-2 and bcl-x(L) were all expressed in spermatogonia during juvenile sp ermatogenesis, but only bcl-w was detected in spermatogonia of adult mice. A similar shift was evident in Sertoli cells. This developmental regulation may co-ordinate physiological germ cell apoptosis in wild type mice and ac count for the time of onset for pathological germ cell apoptosis in bcl-w-/ - animals.