|
||
Original Article |
6ß1 and Is CD9-dependent
Correspondence to: Diana G. Myles, Department of Molecular and Cellular Biology, University of California Davis, One Shields Avenue, Davis, CA 96516. Tel:(530) 752-1553 Fax:(530) 752-7522 E-mail:dgmyles{at}ucdavis.edu.
Previous results, based on inhibition of fertilization by an anti
6 integrin mAb (GoH3), suggest that the
6ß1 integrin on mouse eggs functions as the receptor for sperm (Almeida, E.A., A.P. Huovila, A.E. Sutherland, L.E. Stephens, P.G. Calarco, L.M. Shaw, A.M. Mercurio, A. Sonnenberg, P. Primakoff, D.G. Myles, and J.M. White. 1995. Cell. 81:10951104). Because the egg surface tetraspanin CD9 is essential for gamete fusion (Kaji, K., S. Oda, T. Shikano, T. Ohnuki, Y. Uematsu, J. Sakagami, N. Tada, S. Miyazaki, and A. Kudo. 2000. Nat. Genet. 24:279282; Le Naour, F., E. Rubinstein, C. Jasmin, M. Prenant, and C. Boucheix. 2000. Science. 287:319321; Miyado, K., G. Yamada, S. Yamada, H. Hasuwa, Y. Nakamura, F. Ryu, K. Suzuki, K. Kosai, K. Inoue, A. Ogura, M. Okabe, and E. Mekada. 2000. Science. 287:321324) and CD9 is known to associate with integrins, recent models of gamete fusion have posited that egg CD9 acts in association with
6ß1 in fusion (Chen, M.S., K.S. Tung, S.A. Coonrod, Y. Takahashi, D. Bigler, A. Chang, Y. Yamashita, P.W. Kincade, J.C. Herr, and J.M. White. 1999. Proc. Natl. Acad. Sci. USA. 96:1183011835; Kaji, K., S. Oda, T. Shikano, T. Ohnuki, Y. Uematsu, J. Sakagami, N. Tada, S. Miyazaki, and A. Kudo. 2000. Nat. Genet. 24:279282; Le Naour, F., E. Rubinstein, C. Jasmin, M. Prenant, and C. Boucheix. 2000. Science. 287:319321; Miyado, K., G. Yamada, S. Yamada, H. Hasuwa, Y. Nakamura, F. Ryu, K. Su- zuki, K. Kosai, K. Inoue, A. Ogura, M. Okabe, and E. Mekada. 2000. Science. 287:321324). Using eggs from cultured ovaries of mice lacking the
6 integrin subunit, we found that the fertilization rate, fertilization index, and sperm binding were not impaired compared with wild-type or heterozygous controls. Furthermore, a reexamination of antibody inhibition, using an assay that better simulates in vivo fertilization conditions, revealed no inhibition of fusion by the GoH3 mAb. We also found that an anti-CD9 mAb completely blocks sperm fusion with either wild-type eggs or eggs lacking
6ß1. Based on these results, we conclude that the
6ß1 integrin is not essential for spermegg fusion, and we suggest a new model in which CD9 acts by itself, or interacts with egg protein(s) other than
6ß1, to function in spermegg fusion.
Key Words: spermegg fusion, tetraspanin, membrane adhesion, oocyte, ovarian cultare
This article has been cited by other articles:
|
|