The influence of extracellular-regulated kinases (ERKs) on granulosa cell fate in the bovine follicle

Each year, infertility in cows costs the dairy industry over $400 million. This project is focused on the onset of follicular atresia in cows; the process by which the egg-bearing follicles die prematurely and can lead to infertility. The cellular mechanisms that influence programmed cell death, or apoptosis, of bovine granulosa cells (bGCs) within follicles are being investigated. In general, the extra-cellular regulated kinases (ERKs) are intracellular signaling proteins believed to influence the proliferation, survival, and differentiation of cells. In the context of follicular atresia, however, the relationship between the onset of apoptosis of bGCs and the effects of ERKs is relatively unknown. In the present study we are utilizing a constitutively active mitogen activated protein kinase (MEK1) to upregulate ERKs in bGCs, and then determine the effect on bGC sensitivity to apoptosis. Cultured bGCs were genetically modified via transduction using a constitutively active MEK1 adenovirus. Currently we are verifying the efficiency of viral transduction, overexpression of MEK-1, and downstream activation of ERK by flow cytometry and immunoblotting. Preliminary results indicate a lack of MEK1 up-regulation in transduced bGCs. Subsequent experiments will focus on optimizing adenovirus transfection in order to test the hypothesis that upregulated ERKs prevent cytokine-induced apoptosis of bGC. Supported by USDA Grant #2013-67016-21071 and the UNH Agricultural Experiment Station