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Gelatinase A and membrane-type matrix metalloproteinases 1 and 2 are responsible for follicle rupture during ovulation in the medaka.

Ogiwara K, Takano N, Shinohara M, Murakami M, Takahashi T

Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan.

Identification of the hydrolytic enzymes involved in follicle rupture during vertebrate ovulation remains a central challenge for research in reproductive biology. Here, we report a previously uncharacterized approach to this problem by using an in vitro ovulation system in the medaka, Oryzias latipes, which is a small freshwater teleost. We found that follicle rupture in the medaka ovary involves the cooperation of at least three matrix metalloproteinases (MMPs), together with the tissue inhibitor of metalloproteinase-2b protein. We determined the discrete roles of each of these proteins during follicle rupture. Our results indicated that gelatinase A induces the hydrolysis of type IV collagen constituting the basement membrane, membrane-type 2 MMP degrades type I collagen present in the theca cell layer, and MT1-MMP and the tissue inhibitor of metalloproteinase-2b are involved in the production and regulation of gelatinase A. These findings will help clarify the mechanism of follicle wall degradation during ovulation in mammalian species.

Published 15 June 2005 in Proc Natl Acad Sci U S A, 102(24): 8442-7.
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