The fusing ability of sperm is bestowed by CD9-containing vesicles released from eggs in mice.
Membrane fusion is an essential step in the encounter of two nuclei from sex cells-sperm and egg-in fertilization. However, aside from the involvement of two molecules, CD9 and Izumo, the mechanism of fusion remains unclear. Here, we show that sperm-egg fusion is mediated by vesicles containing CD9 that are released from the egg and interact with sperm. We demonstrate that the CD9(-/-) eggs, which have a defective sperm-fusing ability, have impaired release of CD9-containing vesicles. We investigate the fusion-facilitating activity of CD9-containing vesicles by examining the fusion of sperm to CD9(-/-) eggs with the aid of exogenous CD9-containing vesicles. Moreover, we show, by examining the fusion of sperm to CD9(-/-) eggs, that hamster eggs have a similar fusing ability as mouse eggs. The CD9-containing vesicle release from unfertilized eggs provides insight into the mechanism required for fusion with sperm.
Miyado
Kenji
K
National Center for Child Health and Development, 2-10-1 Okura, Setagaya, Tokyo 157-8535, Japan. kmiyado@nch.go.jp
Yoshida
Keiichi
K
Yamagata
Kazuo
K
Sakakibara
Keiichi
K
Okabe
Masaru
M
Wang
Xiaobiao
X
Miyamoto
Kiyoko
K
Akutsu
Hidenori
H
Kondo
Takahiko
T
Takahashi
Yuji
Y
Ban
Tadanobu
T
Ito
Chizuru
C
Toshimori
Kiyotaka
K
Nakamura
Akihiro
A
Ito
Masahiko
M
Miyado
Mami
M
Mekada
Eisuke
E
Umezawa
Akihiro
A
D000818:Animals; D015703:Antigens, CD / Q000378:metabolism*; D005260:Female; D005306:Fertilization; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008297:Male; D008562:Membrane Glycoproteins / Q000172:deficiency / Q000378:metabolism*; D051379:Mice; D010063:Ovum / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D022142:Secretory Vesicles / Q000378:metabolism* / Q000648:ultrastructure; D013084:Sperm-Ovum Interactions / Q000502:physiology*; D013094:Spermatozoa / Q000166:cytology*; D060245:Tetraspanin 29
D015703:Antigens, CD; C554870:Cd9 protein, mouse; D008562:Membrane Glycoproteins; D011993:Recombinant Fusion Proteins; D060245:Tetraspanin 29; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins