Masayuki Shimada got his Ph.D. degree from Graduate School of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan, in 2003. He worked as Visiting Researcher in the Department of Molecular & Cellular Biology, Baylor College of Medicine, Houston, Texas, USA (worked with JoAnne S. Richards, Ph.D.), from 2004 to 2005. Shimada currently serves as an Associate Professor at Laboratory of Reproductive Endocrinology, Graduate School of Biosphere Science, Hiroshima University, Hiroshima, Japan. His special field is ovarian endocrinology, especially ovulation. He investigated how to regulate ovulation by LH surge. He identified the expression of EGF like factors, Areg, Ereg, Btc, and Nrg1 in granulosa cells after LH surge. EGF like factors act on cumulus cells to induce not only the target gene expressions but also modification of focal adhesion complexes. Both changes are required to accumulate hyaluronan rich matrix among cumulus cells, called cumulus expansion during ovulation process. Interestingly, the large molecule hyaluronan rich matrix is degradated to small fragments during fertilization process. The small fragments stimulate cumulus cells via Toll like receptor (TLR) dependent manner. TLRs expressed on cumulus cells are involved in the expression and secession of chemokine families that act on their receptors expressed on sperm. The stimuli are required for the induction of sperm capacitation. Thus, cumulus cells are unique niche type cells that have specific roles in oocyte maturation and fertilization.
Biography Updated on 7 February 2013