Seminal vesicle secretion 2 (SVS2) is a protein secreted by the mouse seminal vesicle. We previously demonstrated that SVS2 regulates fertilization in mice; SVS2 is attached to a ganglioside GM1 on the plasma membrane of the sperm head and inhibits sperm capacitation in in vitro fertilization as a decapacitation factor. Furthermore, male mice lacking SVS2 display prominently reduced fertility in vivo, which indicates that SVS2 protects spermatozoa from some spermicidal attack in the uterus. In this study, we tried to investigate the mechanisms by which SVS2 controls in vivo sperm capacitation. SVS2-deficient males that mated with wild-type partners resulted in decreased cholesterol levels on ejaculated sperm in the uterine cavity. SVS2 prevented cholesterol efflux from the sperm plasma membrane and incorporated liberated cholesterol in the sperm plasma membrane, thereby reversibly preventing the induction of sperm capacitation by bovine serum albumin and methyl-beta-cyclodextrin in vitro. SVS2 enters the uterus and the uterotubal junction, arresting sperm capacitation in this area. Therefore, our results show that SVS2 keeps sterols on the sperm plasma membrane and plays a key role in unlocking sperm capacitation in vivo.
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13 November 2014
Seminal Vesicle Secretion 2 Acts as a Protectant of Sperm Sterols and Prevents Ectopic Sperm Capacitation in Mice
Naoya Araki,
György Trencsényi,
Zoárd T. Krasznai,
Enikő Nizsalóczki,
Ayako Sakamoto,
Natsuko Kawano,
Kenji Miyado,
Kaoru Yoshida,
Manabu Yoshida
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Biology of Reproduction
Vol. 92 • No. 1
January 2015
Vol. 92 • No. 1
January 2015
cholesterol efflux
seminal plasma
sperm capacitation
SVS2