A role for a TIMP-3-sensitive, Zn(2+)-dependent metalloprotease in mammalian gamete membrane fusion.
During fertilization, sperm and egg plasma membranes adhere and then fuse by a mechanism that is not well understood. Zinc metalloproteases are necessary for some intercellular fusion events, for instance, cell-cell fusion in yeast. In this study we tested the effects of class-specific and family-specific protease inhibitors on mouse gamete fusion. Capacitated, acrosome-reacted sperm and zona-free eggs were used in assays designed to define the effects of inhibitors on sperm-egg plasma membrane binding or fusion. Inhibitors of the aspartic, cysteine, and serine protease classes had no effect on sperm-egg binding or fusion. Both a synthetic metalloprotease substrate (succinyl-Ala-Ala-Phe-amidomethylcoumarin) and the zinc chelator 1,10-phenanthroline inhibited sperm-egg fusion but did not decrease sperm-egg binding. The fusion-inhibition effect of phenanthroline was reversible and activity of the inhibitable zinc metalloprotease was shown to be required during a short time window, the first 15 min after insemination. Tissue inhibitor of metalloprotease-3 and Ro 31-9790, specific inhibitors of zinc metalloproteases in the matrixin and adamalysin families, also inhibited sperm-egg fusion but not sperm-egg binding. These data indicate a role in gamete fusion for one or more zinc metalloproteases of the matrixin and/or adamalysin families that act after plasma membrane binding and before sperm-egg membrane fusion.
Correa
L M
LM
Section of Molecular and Cellular Biology, University of California at Davis, 95616, USA.
Cho
C
C
Myles
D G
DG
Primakoff
P
P
D000818:Animals; D005260:Female; D008297:Male; D008666:Metalloendopeptidases / Q000502:physiology*; D051379:Mice; D008813:Mice, Inbred ICR; D013084:Sperm-Ovum Interactions; D019717:Tissue Inhibitor of Metalloproteinase-3 / Q000502:physiology*; D015032:Zinc
D019717:Tissue Inhibitor of Metalloproteinase-3; D008666:Metalloendopeptidases; D015032:Zinc