Functional implications of membrane modification with semenogelins for inhibition of sperm motility in humans

Abstract

Semenogelin I and II (Sgs) are the major component of human semen coagulum. The protein is rapidly cleaved after ejaculation by a prostate-specific antigen, resulting in liquefaction of the semen coagulum and the progressive release of motile spermatozoa. Sgs inhibit human sperm motility; however, there is currently no information on its effect on the sperm membrane. This study investigated the role of Sgs on human sperm motility through regulation of membrane potential and membrane permeability. Fresh semen samples were obtained from normozoospermic volunteers, and studies were conducted using motile cells selected using the swim-up method. Sgs changed the characteristics of sperm motion from circular to straightforward as evaluated by a computer-assisted motility analyzer, and all parameters were decreased more than 2.5 mg/mL. The results demonstrate that Sgs treatment immediately hyperpolarized the membrane potential of swim-up-selected sperm, changed the membrane structure, and time-dependently increased membrane permeability, as determined through flow cytometric analysis. The biphasic effects of Sgs were time- and dose-dependent and partially reversible. In addition, a monoclonal antibody against Sgs showed positive binding to cell membrane proteins in fixed cells, observed with confocal fluorescence microscopy. These results demonstrate that Sgs modifies the membrane structure, indirectly inhibiting motility, and provides suggestions for a therapy for male infertility through selection of a functional sperm population using Sgs.

Electroejaculation and semen buffer evaluation in the microbat Carollia perspicillata

“…Semenogelin is a protein that mechanically traps spermatozoa and inhibits sperm motility and capacitation [17]. The addition of trypsin, a serine protease, in the seminal extender can precipitate the dissolution of the sperm coagulum [18][19][20].…”

Association of Seminal Plasma Motility Inhibitors/Semenogelins with Sperm in Asthenozoospermia-Infertile Men

“…Sgs and/or their degradation products may be natural regulators of sperm motility [18,19] and capacitation [20] . Previously, we revealed that the SPMI/Sg content of seminal plasma was negatively correlated with sperm motility in normal subjects [21] .…”

Relationship between Semenogelins bound to human sperm and other semen parameters and pregnancy outcomes

“…Such a tendency was not observed in any of the other parameters, including the proportion of SEMG+. Although the precise molecular mechanism underlying the controlling fertilizing capacity of sperm in vivo have not been revealed, the role of SEMGs on sperm were well studied and proved to control motility and capacitation [ 8 , 16 – 18 ]. Moreover, according to our analysis in knockout mice, seminal vesicle secretion 2 (SVS2), an orthologue of SEMGs, is essential for in vivo fertilization [ 13 ].…”