Induction of Epididymal Boar Sperm Capacitation by pB1 and BSP-A1/-A2 Proteins, Members of the BSP Protein Family1

Abstract

A family of proteins designated BSP-A1, BSP-A2, BSP-A3, and BSP-30-kDa, collectively called BSP (bovine seminal plasma) proteins, constitute the major protein fraction of bull seminal plasma. BSP proteins can stimulate sperm capacitation by inducing cholesterol and phospholipid efflux from sperm. Boar seminal plasma contains one homologous protein of the BSP family, named pB1; however, its physiological role is still unknown. In the current study, we report a novel method to purify pB1 from boar seminal plasma by chondroitin sulfate B-affinity chromatography and reverse-phase-high performance liquid chromatography. We also studied the effect of pB1, BSP-A1/-A2, and whole boar seminal plasma on boar sperm capacitation. Boar epididymal sperm were washed, preincubated in noncapacitating medium containing pB1 (0, 2.5, 5, 10 or 20 microg/ml), BSP-A1/-A2 (0 or 20 microg/ml) proteins, or whole seminal plasma (0, 250, 500, or 1000 microg/ml), then washed and incubated in capacitating medium. Acrosomal integrity was assessed by chlortetracycline staining. The status of sperm capacitation was evaluated by the capacity of sperm to undergo the acrosome reaction initiated by the addition of the calcium ionophore, A23187. The pB1 and BSP-A1/-A2 proteins increased epididymal sperm capacitation as compared with control (sperm preincubated without proteins). This effect reached a maximum level at 10 microg/ml pB1 and at 20 microg/ml BSP-A1/-A2 (2.3- and 2.2-fold higher than control, respectively). Whole boar seminal plasma did not induce sperm capacitation. In addition, pB1 bound to boar epididymal sperm and was lost during capacitation. These results indicate that BSP proteins and their homologs in other species induce sperm capacitation in a similar way.

SL15: A seminal plasma‐derived lectin from the sperm of llama (Lama glama)

“…Seminal plasma‐derived heparin‐binding proteins that associate with ejaculated sperm are common in other species (Feng, Mehta, El‐Assal, Wu, & Besner, ; Mader, Smyth, Marshall, & Hoskin, ), including Binder of sperm (BSP) proteins in bulls (Manjunath & Sairam, ), goats (Villemure, Lazure, & Manjunath, ), pigs (Lusignan, Bergeron, Crete, Lazure, & Manjunath, ), horses (Calvete et al, ), and bison (Boisvert, Bergeron, Lazure, & Manjunath, ). BSP interacts with heparin through its two fibronectin type II domains (Feng et al, ).…”

Seminal Plasma Proteins as Modulators of the Sperm Function and Their Application in Sperm Biotechnologies

“…2007). Similarly, pB1, a member of the BSP family in porcine, was able to potentiate the capacitation of boar epididymal sperm, which suggests that the mechanism of action of this protein family during sperm capacitation could be conserved among species (Lusignan et al. 2007).…”

Sperm surface changes and physiological consequences induced by sperm handling and storage

“…However, AQN-3 has also been shown to be involved in the binding of capacitated boar spermatozoa to the zona pellucida , indicating that release of seminal plasma factors from the sperm surface is not a straightforward process. Moreover, the heparin-binding BSP protein, pB1, has also been shown to stimulate capacitation of epididymal boar spermatozoa by inducing cholesterol and phospholipid efflux from the sperm membrane (Lusignan et al 2007), which has been extensively documented with bull BSP proteins. Incubation of highly diluted boar spermatozoa (extended to a level that mimicked sex-sorting: 0.3-1!10 6 sperm/ml) with heparin-binding proteins was detrimental to in vitro sperm function (Centurion et al 2003), causing a timeand dose-dependent decrease in the motility, viability and mitochondrial integrity of spermatozoa.…”