Functional aspects of seminal plasma and sperm proteins and their potential as molecularmarkers of fertility

Abstract

Molecular components of sperm and in the media surrounding them influence bull fertility. Given this concept, proteins of the seminal plasma modulate crucial functions and events of reproduction, such as sperm motility and capacitation, cell protection, acrosome reaction, fertilization and embryonic development. Sperm proteins are also important for successful fertilization, egg activation and embryo development. Empirical associations between seminal and sperm proteins and fertility in the bovine indicate that these proteins are potential molecular markers of the male reproductive status.

Markers for Sperm Freezability and Relevance of Transcriptome Studies in Semen Cryopreservation: A Review

“…The protein constellation of the SP and sperm cells, and their distinct subcompartments have been well documented in a numerous animal species, using a plethora of proteomicbased techniques [6,37,38]. While some speciic sperm protein markers facilitating good semen freezability have been identiied [10,24,39,40], their function depends on the presence of mRNA that can be translated into proteins in the spermatozoa. Moreover, the diferential expression paterns of certain classes of SP and sperm proteins following cryopreservation have been used as markers for semen freezability [3,6,10,[39][40][41][42][43][44].…”

“…While some speciic sperm protein markers facilitating good semen freezability have been identiied [10,24,39,40], their function depends on the presence of mRNA that can be translated into proteins in the spermatozoa. Moreover, the diferential expression paterns of certain classes of SP and sperm proteins following cryopreservation have been used as markers for semen freezability [3,6,10,[39][40][41][42][43][44]. Regarding boar semen, the physiological functions of SP and sperm proteins and their associations with freezability have been summarized in recent reviews by Yeste [3,10].…”

“…In the bull, higher concentrations of a 26-kDa SP protein, known as lipocalin-type prostaglandin D synthase (L-PGDS), and a 13-kDa acidic seminal luid protein (aSFP) were associated with high-fertility bulls, suggesting the importance of these proteins as freezability markers [41]. Moreover, a fertilityassociated protein, osteopontin (OPN), an acidic glycoprotein occurring in the bovine SP, has been shown to induce capacitation and improve viability of spermatozoa by inhibiting the apoptotic pathways [39,41]. Bovine SP proteins, collectively known as binder of sperm (BSP) proteins (BSP1, BSP 3, and BSP 5), bind to choline phospholipids in the sperm plasma membrane and are implicated in semen freezability [22,39,41,42].…”

“…Moreover, a fertilityassociated protein, osteopontin (OPN), an acidic glycoprotein occurring in the bovine SP, has been shown to induce capacitation and improve viability of spermatozoa by inhibiting the apoptotic pathways [39,41]. Bovine SP proteins, collectively known as binder of sperm (BSP) proteins (BSP1, BSP 3, and BSP 5), bind to choline phospholipids in the sperm plasma membrane and are implicated in semen freezability [22,39,41,42]. Recently, it has been conirmed that BSP1, one of the most abundantly expressed BSP proteins (representing approximately 25-47% of the total proteins in bovine SP), consists of four molecular forms that have varying cryoprotective efects on the bull spermatozoa [42].…”

“…In boar sperm extracts, the levels of outer dense iber 2 (ODF2), A-kinase-anchoring protein 3 or 4 (AKAP3; AKAP4), heatshock protein 90 (HSP90AA1), voltage-dependent anion channel 2 (VDAC2), acrosin-binding protein (ACRBP), and triosephosphate isomerase 1 (TP1) activities were associated with semen freezability [10,40]. Furthermore, ODFs provide a stable and elastic structure to the lagellum of the spermatozoon, supporting its movement and protecting it during the epididymal transit and ejaculation [36,39,40]. The ODF2 seems to be essential to ODF assembly, and its overexpression in frozen-thawed boar spermatozoa was associated with reduced post-thaw semen quality [40].…”