Store-operated Ca2+ entry and gonadotropin-induced [Ca2+]i rises in porcine cumulus cells
Abstract
The costs of assisted reproductive technologies in humans and domestic animals are high and outcomes are often unsuccessful. Increasing our understanding the mechanisms which control oocyte maturation, developmental competence and fertilization will enhance the potential to increase efficiency of assisted reproductive technologies. Oscillatory calcium (Ca2+) signals in the oocyte are known to influence development. We have focused on store-operated Ca2+ entry (SOCE) in oocytes during fertilization and the roles of Orai1, a Ca2+ channel protein in the plasma membrane, and Stim1, a Ca2+ sensing protein in the endoplasmic reticulum. The underlying mechanisms by which bidirectional communication between the oocyte and surrounding cumulus cells (CC) contributes to maturation of the oocyte are not completely understood. Objectives of these studies are to 1) confirm presence of Stim1 and Orai1 proteins in porcine CCs; and 2) verify and characterize SOCE in CC. The presence of Orai1 and Stim1 in porcine cumulus cells was detected using immunoblotting and immunocytochemistry. Functional SOCE was confirmed and characterized by monitoring changes in intracellular free Ca2+ concentration [Ca2+]i in cultured CC in response to Ca2+ pump inhibitors and gonadotropins. These studies will provide the basis for understanding Ca2+ signaling in cumulus cells. Further studies will be needed to determine if Orai1 and Stim1 are mediators of the observed changes in [Ca2+] i in CC and if resultant Ca2+ signals are transmitted to and have an effect on oocyte maturation or fertilization. This project was supported by Agriculture and Food Research Initiative Competitive Grant no. 2011-67015-30006 from the USDA National Institute of Food and Agriculture.
Degree
M.S.
Advisors
Jaeger, Purdue University.
Subject Area
Cellular biology
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