Major Proteins of Bovine Seminal Plasma Modulate Sperm Capacitation by High-Density Lipoprotein1

Abstract

Bovine seminal plasma (BSP) contains four similar proteins secreted by the seminal vesicles, designated BSP-A1, -A2, -A3, and -30 kDa. These proteins bind to choline phospholipids on the surface of the sperm after ejaculation. These BSP proteins also interact with heparin, apolipoprotein A-I (apoA-I) and apoA-I associated with high-density lipoprotein (HDL). The HDL and heparin present in the female reproductive tract have been implicated in sperm capacitation and the acrosome reaction (AR). This study was undertaken to determine whether or not these BSP proteins and HDL could modulate the capacitation of sperm, and to determine the combined effect of HDL and heparin on capacitation. Washed bovine epididymal sperm were preincubated in buffer containing BSP proteins, washed, and incubated with lipoproteins (HDL, and low- and very low-density lipoproteins) or liposomes with or without apoA-I in the presence or absence of heparin. The percentage of capacitated sperm was evaluated after the AR was induced with lysophosphatidylcholine. HDL alone (160 microg/ml) after an 8-h incubation stimulated the AR of epididymal sperm. The percentage of HDL-enhanced AR further increased when sperm were preincubated with BSP proteins. ApoA-I-liposomes stimulated the AR more rapidly (5 h, 160 microg/ml) than HDL. When sperm were preincubated with BSP proteins, the percentage of apoA-I-enhanced AR further increased. In contrast, when liposomes without apoA-I or when low- or very low-density lipoproteins or lipoprotein-depleted serum was used, no significant increase in the AR was detected with or without BSP proteins. When heparin and HDL or apoA-I-liposomes were used together, their combined effects on the AR were not additive. These results indicate that BSP proteins modulate the process of capacitation induced by heparin, HDL, and apoA-I-liposomes.

Biochemical and seminal parameters of lambs fed palm kernel cake under grazing system

“…This is the major lipoprotein fraction carrying cholesterol from periferic tissues to liver. Moreover, HDL plays a key role in the male reproductive system, which is associated with sperm capacitation and the acrosome reaction (Therien et al, 1997). Sitmo (2014) reported means of HDL in rams ranging from 46.10 to 71 mg dL −1 .…”

Characterization of proteins in cryopreserved and non-cryopreserved seminal plasma of dairy bulls of dif-fering fertility

“…Abundant low molecular weight bovine seminal plasma proteins were replaced during cryopreservation by high molecular weight extender-derived chicken structural proteins. Major bovine seminal plasma proteins PDC-109 (BSP-A1/A2), BSP-A3 and BSP-30 kDa play important roles in fertility by maintaining sperm in an appropriate state in the female tract until the oocyte reaches the site of fertilization [10][11][12][13]. It is unclear whether the effect of processing that decreased the abundance of these BSP proteins by more than half would render them ineffective in preventing premature capacitation and acrosome reaction of sperm from normal fertility bulls in the female tract.…”

Improving bovine semen diluents: insights from the male and female reproductive tracts, and the potential relevance of cervical mucins

“…Free seminal BSP proteins may leave sperm susceptible to damage during cryopreservation by stimulating efflux of cholesterol and phospholipid from the sperm plasma membrane (Thérien et al, 1997). Srivastava et al (2012) employed an innovative method to sequester BSP1 from the semen during collection.…”