International Journal of Molecular Sciences Article Serine Protease Inhibitor SERPINE2 Reversibly Modulates Murine Sperm Capacitation Sheng-Hsiang Li 1,2, Yuh-Ming Hwu 1,2,3,4, Chung-Hao Lu 3, Ming-Huei Lin 2,3, Ling-Yu Yeh 1 and Robert Kuo-Kuang Lee 1,3,5,* 1 Department of Medical Research, Mackay Memorial Hospital, Tamsui District, New Taipei City 251, Taiwan;
[email protected] (S.-H.L.);
[email protected] (Y.-M.H.);
[email protected] (L.-Y.Y.) 2 Mackay Junior College of Medicine, Nursing, and Management, Beitou District, Taipei City 112, Taiwan;
[email protected] 3 Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei City 104, Taiwan;
[email protected] 4 Mackay Medical College, Sanzhi District, New Taipei City 252, Taiwan 5 Department of Obstetrics and Gynecology, Taipei Medical University, Taipei City 110, Taiwan * Correspondence:
[email protected]; Tel.: +886-2-2543-3535 Received: 2 May 2018; Accepted: 17 May 2018; Published: 19 May 2018 Abstract: SERPINE2 (serpin peptidase inhibitor, clade E, member 2), predominantly expressed in the seminal vesicle, can inhibit murine sperm capacitation, suggesting its role as a sperm decapacitation factor (DF). A characteristic of DF is its ability to reverse the capacitation process. Here, we investigated whether SERPINE2 can reversibly modulate sperm capacitation. Immunocytochemical staining revealed that SERPINE2 was bound onto both capacitated and uncapacitated sperm. It reversed the increase in BSA-induced sperm protein tyrosine phosphorylation levels. The effective dose and incubation time were found to be >0.1 mg/mL and >60 min, respectively. Calcium ion levels in the capacitated sperm were reduced to a level similar to that in uncapacitated sperm after 90 min of incubation with SERPINE2.