ANALYSIS OF APOPTOSIS AND EXPRESSION OF BCL-2 GENE FAMILY MEMBERS IN THE HUMAN AND BABOON OVARY

Recent data support a role for apoptosis, under tight regulatory contr ol by bcl-2, oxidative stress response, tumor suppressor, and GASP gen e family members, in mediating granulosa cell demise during follicular atresia in the rodent and avian ovary. Herein we evaluated the occurr ence of apoptosis in the human and baboon ovary relative to follicular health status, and analyzed expression of several cell death genes in these tissues. In situ localization of DNA strand breaks in fixed hum an and baboon ovarian tissue sections indicated that apoptosis was ess entially restricted to granulosa cells of atretic antral follicles, Bi ochemical analysis of DNA oligonucleosomes in individual follicles iso lated from baboon ovaries during the ovulatory phase revealed the pres ence of apoptotic DNA fragments in subordinate but not dominant follic les, thus substantiating the in situ labeling studies. Messenger RNA t ranscripts encoded by the bar death susceptibility gene, the bcl-x(lon g) survival gene, the bcl-x(short) pro-apoptosis gene, the p53 tumor s uppressor gene, and two members of the CASP gene family (CASP-2/lch-1, CASP-3/CPP32), were detected by Northern blot analysis of total RNA p repared either from human ovaries or from Percoll-purified granulosa-l utein cells obtained from patients undergoing assisted reproductive te chnologies. Lastly, immunohistochemical localization of the BAX death- susceptibility protein in the human ovary revealed abundant expression in granulosa cells of early atretic follicles, whereas BAX protein wa s extremely low or non-detectable in healthy or grossly-atretic follic les. We conclude that apoptosis occurs during, and is probably respons ible for, follicular atresia in the human and baboon ovary. Moreover, apoptosis in the human ovary is likely controlled by altered expressio n of the same cohort of cell death regulatory factors recently implica ted as primary determinants of apoptosis induction or suppression in t he rodent ovary.