Serine Protease Inhibitor SERPINE2 Reversibly Modulates Murine Sperm Capacitation.

Sheng-Hsiang Li,Robert Lee,Yuh-Ming Hwu,Chung-Hao Lu,Ling-Yu Yeh,Ming-Huei Lin

doi:10.3390/ijms19051520

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. In addition, the acrosome reaction of capacitated sperm was inhibited after 90 min of incubation with SERPINE2. Oviductal sperm was readily induced to undergo the acrosome reaction using the A23187 ionophore; however, the acrosome reaction was significantly reduced after incubation with SERPINE2 for 60 and 120 min. These findings suggested that SERPINE2 prevented as well as reversed sperm capacitation in vitro. It also prevented the acrosome reaction in in vivo-capacitated sperm isolated from the oviduct. Thus, SERPINE2 could reversibly modulate murine sperm capacitation.

Highlights

IntroductionCapacitation, a physiological process in the sperm, was first described in the early 1950s [1,2], in which the sperm resides in the female reproductive tract until it gains the ability to fertilize an egg. Capacitation, a physiological process in the sperm, was first described in the early 1950s [1,2], in which the sperm resides in the female reproductive tract until it gains the ability to fertilize an egg
Capacitation, a physiological process in the sperm, was first described in the early 1950s [1,2], in which the sperm resides in the female reproductive tract until it gains the ability to fertilize an egg.It is a complex change and is believed to be initiated by the removal of cholesterol from the sperm plasma membrane [3,4,5,6], leading to changes in the membrane structure and fluidity and increase in the permeability of the sperm for calcium and bicarbonate ions
The seminal plasma is a mixture of secretions from the male accessory sexual glands, mainly containing seminal vesicle secretions

Summary

Introduction

Capacitation, a physiological process in the sperm, was first described in the early 1950s [1,2], in which the sperm resides in the female reproductive tract until it gains the ability to fertilize an egg. Capacitation, a physiological process in the sperm, was first described in the early 1950s [1,2], in which the sperm resides in the female reproductive tract until it gains the ability to fertilize an egg It is a complex change and is believed to be initiated by the removal of cholesterol from the sperm plasma membrane [3,4,5,6], leading to changes in the membrane structure and fluidity and increase in the permeability of the sperm for calcium and bicarbonate ions. A series of downstream signaling occurs, including an increase in the levels of sperm intracellular calcium ion ([Ca2+ ]i ) and pH, thereby activating adenylyl cyclase and leading to an increase in the intracellular levels of cyclic AMP (cAMP). The activation of cAMP-dependent protein kinase induces tyrosine phosphorylation of a subset of sperm proteins [7]. It has been shown to reverse sperm capacitation [8]

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Conclusion