title: SERPINE2, a serine protease inhibitor extensively expressed in adult male mouse reproductive tissues, may serve as a murine sperm decapacitation factor.
abstract: SERPINE2, one of the potent serine protease inhibitors that modulates the activity of plasminogen activator and thrombin, is implicated in many biological processes. In the present study, we purified SERPINE2 from mouse seminal vesicle secretion (SVS), using liquid chromatography and identified it by liquid chromatography/tandem mass spectrometry, and it showed potent inhibitory activity against the urokinase-type plasminogen activator. SERPINE2 was expressed predominantly in seminal vesicles among murine male reproductive tissues. It was immunolocalized to the SVS and mucosal epithelium of the seminal vesicle, epididymis, coagulating gland, and vas deferens. In the testes, SERPINE2 was immunostained in spermatogonia, spermatocytes, spermatids, Leydig cells, and spermatozoa. SERPINE2 was also detected on the acrosomal cap of testicular and epididymal sperm and was suggested to be an intrinsic sperm surface protein. The purified SERPINE2 protein could bind to epididymal sperm. A prominent amount of SERPINE2 was detected on ejaculated and oviductal spermatozoa. Nevertheless, SERPINE2 was detected predominantly on uncapacitated sperm, indicating that SERPINE2 is lost before initiation of the capacitation process. Moreover, SERPINE2 could inhibit in vitro bovine serum albumin-induced sperm capacitation and prevent sperm binding to the egg, thus blocking fertilization. It acts through preventing cholesterol efflux, one of the initiation events of capacitation, from the sperm. These findings suggest that the SERPINE2 protein may play a role as a sperm decapacitation factor.
authors.affiliation: Department of Medical Research, Mackay Memorial Hospital, Taipei, Taiwan, ROC.
authors.forename: Chung-Hao
authors.initials: CH
authors.lastname: Lu
authors.forename: Robert Kuo-Kuang
authors.initials: RK
authors.lastname: Lee
authors.forename: Yuh-Ming
authors.initials: YM
authors.lastname: Hwu
authors.forename: Shian-Ling
authors.initials: SL
authors.lastname: Chu
authors.forename: Ying-Jie
authors.initials: YJ
authors.lastname: Chen
authors.forename: Wei-Chao
authors.initials: WC
authors.lastname: Chang
authors.forename: Shau-Ping
authors.initials: SP
authors.lastname: Lin
authors.forename: Sheng-Hsiang
authors.initials: SH
authors.lastname: Li
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D054337:Cell Dedifferentiation / Q000187:drug effects / Q000502:physiology; D004542:Ejaculation; D005837:Genitalia, Male / Q000166:cytology / Q000378:metabolism*; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D008969:Molecular Sequence Data; D011485:Protein Binding; D012098:Reproduction / Q000502:physiology; D012661:Semen / Q000166:cytology / Q000378:metabolism; D015842:Serine Proteinase Inhibitors / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology; D058258:Serpin E2 / Q000302:isolation & purification / Q000378:metabolism* / Q000494:pharmacology / Q000502:physiology*; D013075:Sperm Capacitation / Q000187:drug effects / Q000502:physiology; D014018:Tissue Distribution
chemical_list: D015842:Serine Proteinase Inhibitors; D058258:Serpin E2; C511869:Serpine2 protein, mouse