Tumor Necrosis Factor (TNF) Receptor Type 2 Is an Important Mediator of TNF alpha Function in the Mouse Ovary

• Published in: Biology of reproduction Vol. 76; no. 2; pp. 224 - 231
• Main Authors: Greenfeld, Chuck R, Roby, Katherine F, Pepling, Melissa E, Babus, Janice K, Terranova, Paul F, Flaws, Jodi Anne
• Format: Journal Article
• Language: English
• Published: Madison, WI Society for the Study of Reproduction, Inc 01.02.2007; Society for the Study of Reproduction
• Subjects: Animals; Animals, Newborn; Biological and medical sciences; Cell Death - physiology; Female; Fundamental and applied biological sciences. Psychology; Hormone metabolism and regulation; Mammalian female genital system; Mice - metabolism; Mice, Inbred C57BL; Mice, Knockout; Morphology. Physiology; Oocytes - metabolism; Oocytes - physiology; Organ Culture Techniques; Ovarian Follicle - growth & development; Ovary - cytology; Ovary - metabolism; Protein Isoforms - metabolism; Receptors, Tumor Necrosis Factor, Type II - metabolism; Tumor Necrosis Factor-alpha - metabolism; Vertebrates: reproduction; follicle; Cytokine; Rodentia; Ovary; Vertebrata; Reproduction; follicular development; Mammalia; Mouse; Cell death; Tumor necrosis factor; Animal; Female genital system; Development; Apoptosis; Biological receptor
• ISSN: 0006-3363; 1529-7268
• DOI: 10.1095/biolreprod.106.055509

It is believed that a finite pool of primordial follicles is established during embryonic and neonatal life. At birth, the mouse ovary consists of clusters of interconnected oocytes surrounded by pregranulosa cells. Shortly after birth these structures, termed germ cell cysts or nests (GCN), break down to facilitate primordial follicle formation. Tumor necrosis factor alpha (TNF) is a widely expressed protein with myriad functions. TNF is expressed in the ovary and may regulate GCN breakdown in rats. We investigated whether it participates in GCN breakdown and follicle formation in mice by using an in vitro ovary culture system as well as mutant animal models. We found that TNF and both receptors (TNFRSF1A and TNFRSF1B) are expressed in neonatal mouse ovaries and that TNF promotes oocyte death in neonatal ovaries in vitro. However, deletion of either receptor did not affect follicle endowment, suggesting that TNF does not regulate GCN breakdown in vivo. Tnfrsf1b deletion led to an apparent acceleration of follicular growth and a concomitant expansion of the primordial follicle population. This expansion of the primordial follicle population does not appear to be due to decreased primordial follicle atresia, although this cannot be ruled out completely. This study demonstrates that mouse oocytes express both TNF receptors and are sensitive to TNF-induced death. Additionally, TNFRSF1B is demonstrated to be an important mediator of TNF function in the mouse ovary and an important regulator of folliculogenesis.