SPINKL, a Kazal-type serine protease inhibitor-like protein purified from mouse seminal vesicle fluid, is able to inhibit sperm capacitation.
We report a secreted serine protease inhibitor Kazal-type-like (SPINKL) protein. The SPINKL protein was purified from mouse seminal vesicle secretions through a series of steps, including ion-exchange chromatography on a diethylaminoethyl-Sephacel column, gel filtration on a Sephadex G-75 column, and ion-exchange HPLC on a Q strong anion exchange column. Further analysis identified several SPINKL proteins with various N-linked carbohydrates. The SPINKL protein has six conserved cysteine residues that are nearly identical to those of members of the SPINK protein family. It was noted that the SPINKL protein showed no inhibitory activities against common serine proteases such as trypsin, chymotrypsin, subtilisin, or elastase. Spinkl mRNA and SPINKL proteins were found to be primarily expressed in seminal vesicles. Immunohistochemistry revealed that the SPINKL protein occurred in the luminal fluid and mucosal epithelium of the seminal vesicles and was regulated by testosterone. The SPINKL protein was able to bind onto sperm and enhance sperm motility. Also, it was able to suppress BSA-stimulated sperm capacitation and block sperm-oocyte interactions in vitro, suggesting that SPINKL may be a decapacitation factor.
Lin
Ming-Huei
MH
Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Mackay Medicine, Nursing and Management College, Taipei, Taiwan.
Lee
Robert Kuo-Kuang
RK
Hwu
Yuh-Ming
YM
Lu
Chung-Hao
CH
Chu
Shian-Ling
SL
Chen
Ying-Jie
YJ
Chang
Wei-Chao
WC
Li
Sheng-Hsiang
SH
D020101:Acrosome Reaction / Q000187:drug effects; D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western / Q000379:methods; D001826:Body Fluids / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D005298:Fertility / Q000187:drug effects; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D053491:Proteinase Inhibitory Proteins, Secretory / Q000235:genetics / Q000302:isolation & purification* / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis; D012669:Seminal Vesicles / Q000737:chemistry*; D016415:Sequence Alignment; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013075:Sperm Capacitation / Q000187:drug effects*; D013094:Spermatozoa / Q000187:drug effects*
D053491:Proteinase Inhibitory Proteins, Secretory; D012333:RNA, Messenger; D015842:Serine Proteinase Inhibitors; C533878:serine protease inhibitor Kazal-type-like protein, mouse