Journal of Cellular Biochemistry

Mechanisms underlying the inhibition of murine sperm capacitation by the seminal protein, SPINKL

Authors

  • Huan-Chin Tseng,

    1. Department of Medical Research, Mackay Memorial Hospital, Tamshui, New Taipei City, Taiwan
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  • Robert Kuo-Kuang Lee,

    1. Department of Medical Research, Mackay Memorial Hospital, Tamshui, New Taipei City, Taiwan
    2. Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan
    3. Department of Obstetrics and Gynecology, Taipei Medical University, Taipei, Taiwan
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  • Yuh-Ming Hwu,

    1. Department of Medical Research, Mackay Memorial Hospital, Tamshui, New Taipei City, Taiwan
    2. Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan
    3. Mackay Medicine, Nursing and Management College, Taipei, Taiwan
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  • Chung-Hao Lu,

    1. Department of Medical Research, Mackay Memorial Hospital, Tamshui, New Taipei City, Taiwan
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  • Ming-Huei Lin,

    1. Department of Medical Research, Mackay Memorial Hospital, Tamshui, New Taipei City, Taiwan
    2. Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan
    3. Mackay Medicine, Nursing and Management College, Taipei, Taiwan
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  • Sheng-Hsiang Li

    Corresponding author
    1. Department of Medical Research, Mackay Memorial Hospital, Tamshui, New Taipei City, Taiwan
    2. Mackay Medicine, Nursing and Management College, Taipei, Taiwan
    • Department of Medical Research, Mackay Memorial Hospital, Tamshui 251, New Taipei City, Taiwan.
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  • Huan-Chin Tseng and Robert Kuo-Kuang Lee contributed equally to this work.

Abstract

SPINKL, a serine protease inhibitor kazal-type-like protein initially found in mouse seminal vesicle secretions, possesses structurally conserved six-cysteine residues of the kazal-type serine protease inhibitor family. However, it has no inhibitory activity against serine proteases. Previously, it was found to have the ability to suppress murine sperm capacitation in vitro. Herein, we investigated the mechanisms underlying the suppressive effect of SPINKL on sperm capacitation. Three in vitro capacitation-enhancing agents, including bovine serum albumin (BSA), methyl-beta-cyclodextrin (MBCD), and dibutyryl cyclic AMP (dbcAMP), coupled with 3-isobutyl-1-methylxanthine (IBMX), were used to evaluate the influence of SPINKL on capacitation signaling. Preincubation of sperm with SPINKL suppressed BSA- and MBCD-induced sperm capacitation by blocking three upstream signals of capacitation that is the cholesterol efflux from sperm plasma membranes, extracellular calcium ion influx into sperm, and increases in intracellular cAMP. Moreover, SPINKL also inhibited downstream signal transduction of capacitation since it suppressed dbcAMP/IBMX and N6-phenyl cAMP (6-Phe-cAMP)-activated cAMP-dependent protein kinase-associated protein tyrosine phosphorylation. Such inhibition is probably mediated by attenuation of SRC tyrosine kinase activity. Furthermore, SPINKL could not reverse capacitation once sperm had been capacitated by capacitation-enhancing agents or capacitated in vivo in the oviduct. SPINKL bound to sperm existed in the uterus but had disappeared from sperm in the oviduct during the sperm's transit through the female reproductive tract. Therefore, SPINKL may serve as an uncapacitation factor in the uterus to prevent sperm from precocious capacitation and the subsequent acrosome reaction and thus preserve the fertilization ability of sperm. J. Cell. Biochem. 114: 888–898, 2013. © 2012 Wiley Periodicals, Inc.

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