Effect of Insulin-Like Growth Factor-1 (IGF-1) on the expression of NFκB and cFLIP in Bovine Granulosa Cells

Infertility, often attributed to follicular atresia, is a growing problem in the agricultural industry. Programmed cell death, also known as apoptosis, is a contributing factor of follicular atresia. It occurs in both the granulosa cells and the oocyte that comprise ovarian follicles. Here, mechanisms influencing the process of apoptosis, via the death receptor Fas, were explored using bovine granulosa cells (bGCs) because Fas-induced apoptosis is a plausible mechanism of follicular atresia. Cell culture techniques, optimized for bGCs, were developed and used throughout the current study. In brief, cultures of bGCs were exposed to Fas ligand (100ng/mL) for 24 hrs. This induced cell death, as measured by MTS assay (p=0.024, n=3 experiments). Subsequent experiments in which doses of insulin-like growth factor-1 (IGF-1) were co-administered indicated that 100ng/ml IGF-1 provides the greatest protection against Fas-induced apoptosis (p= 0.001, n=3 experiments). Currently, we are testing the hypothesis that IGF-1 protects bGCs from Fas-induced apoptosis by stimulating the expression of cellular FLICE-like inhibitory protein (cFLIP) and the activation of nuclear factor-κB (NFκB), two molecules thought to protect granulosa cells from apoptosis. IGF-1-stimulated expression of cFLIP and NFκB will be assessed by immunoblots and in-cell western assays. This project was supported by the Hamel Center for Undergraduate Research (SD) and USDA grant no. 2013-67016-21071 (DHT)