Regulated expression of inhibitor of apoptosis protein 3 in the rat corpus luteum.
We sought to investigate the role inhibitor of apoptosis proteins (IAPs) play in the life cycle of the corpus luteum (CL) of the rat. We isolated two clones with amino acid homology to rat IAP2 (BIRC 3) and three to rat IAP3 (rIAP3; BIRC 4). The expression of rIAP3 mRNA was examined in the rat CL during and after pregnancy, in Day 8 pregnant rats after 24-h treatment of gonadotropin-releasing hormone-agonist (GnRH-Ag), and in a CL organ culture model of spontaneous apoptosis in the absence of tropic support with and without superoxide dismutase. We used real-time RT-PCR to quantitate rIAP3 mRNA expression. Interestingly, a significant reduction in rIAP3 levels was seen at the time of CL regression in the course of natural pregnancy and the GnRH-Ag model. Surprisingly, rIAP3 mRNA levels in the CL organ culture model of spontaneous apoptosis failed to show significant changes, although TUNEL (terminal deoxynucleotide transferase-mediated dUTP nick end-labeling) reaction showed 30%-40% of the cells undergoing DNA fragmentation after 2 h in culture. In situ hybridization revealed that rIAP3 expression was localized to the cytoplasm of luteal and granulosa cells. These data clearly demonstrate both the presence of IAPs in the rat CL and the regulation of rIAP3 during in vivo apoptotic cell death, indicating a role for IAPs in the maintenance of CL function and demise.
Lareu
Ricky R
RR
School of Anatomy and Human Biology, The University of Western Australia, Crawley, Western Australia 6009, Australia.
Lacher
Markus D
MD
Bradley
Cara K
CK
Sridaran
Rajagopala
R
Friis
Robert R
RR
Dharmarajan
Arun M
AM
D000818:Animals; D015152:Blotting, Northern; D003001:Cloning, Molecular; D003338:Corpus Luteum / Q000378:metabolism*; D005260:Female; D017403:In Situ Hybridization; D020287:In Situ Nick-End Labeling; D051034:Inhibitor of Apoptosis Proteins; D003341:Luteolysis / Q000502:physiology; D009924:Organ Culture Techniques; D011247:Pregnancy; D014176:Protein Biosynthesis; D011506:Proteins; D012313:RNA / Q000096:biosynthesis; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013482:Superoxide Dismutase / Q000378:metabolism
D051034:Inhibitor of Apoptosis Proteins; D011506:Proteins; C494837:Xiap protein, rat; D012313:RNA; D013482:Superoxide Dismutase