Abstract: 407

SURVIVIN, A NOVEL ANTI-APOPTOSIS GENE, IS EXPRESSED IN THE RAT OVARY.

Randy Wade¹ , Celina Zerbinatti¹ , Dario Altieri² , Cheryl Dyer¹
Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, USA ¹
Department of Pathology, Yale University School of Medicine, New Haven, Connecticut, USA ²

Apoptosis is the mechanism that drives follicular atresia, but relatively little is known about the mechanisms which protect theca and interstitial cells (TIC) from apoptosis. A family of proteins that prevent apoptosis are termed Inhibitor of Apoptosis Proteins (IAPs). Four members of the IAP family have been found in ovarian extracts. Expression of two of these four IAPs is regulated by gonadotropin stimulation and IAPs are highly expressed in the surviving theca compartment of atretic follicles. A novel member of the IAP family has been discovered and called survivin for its putative role in suppressing apoptosis. Survivin is a 16.5kDa, intracellular protein that has sequence homology to other members of the IAP family. Survivin is highly expressed in apoptosis-regulated fetal tissues, adult tissues that commonly express other anti-apoptosis genes such as bcl-2, and in all of the most common types of cancer. To test survivin’s potential role in follicular atresia, we used polyclonal and monoclonal antibodies and detected survivin in immunoblot analysis of protein lysates from adult, cycling rat tissues. To establish that survivin is expressed in TIC, we used ovaries from immature, hypophysectomized (hypox) rats, because the loss of gonadotropins results in extensive follicular atresia. Four days post-hypox, the ovaries were removed and the TIC were isolated and cultured with luteinizing hormone (LH). Fluorescence immunocytochemistry demonstrated that TIC express survivin and its expression appears to increase with LH stimulation. We suggest that TIC survivin expression protects the cells from apoptosis and contributes to successful theca transition into secondary interstitial cells.

    This abstract is being presented on Monday, August 2 at 2:30 PM at Todd 125.