Differential abundances of four forms of Binder of SPerm 1 in the seminal plasma of Bos taurus indicus bulls with different patterns of semen freezability

Abstract

The Binder of SPerm 1 (BSP1) protein is involved in the fertilization and semen cryopreservation processes and is described to be both beneficial and detrimental to sperm. Previously, the relationship of BSP1 with freezability events has not been completely understood. The objective of this work was to determine the differential abundance of the forms of the BSP1 protein in cryopreserved seminal plasma of Bos taurus indicus bulls with different patterns of semen freezability using proteomics. A wide cohort of adult bulls with high genetic value from an artificial insemination center was used as donors of high quality, fresh semen. Nine bulls presenting different patterns of semen freezability were selected. Two-dimensional gel electrophoresis showed differential abundance in a group of seven protein spots in the frozen/thawed seminal plasma from the bulls, ranging from 15 to 17 kDa, with pI values from 4.6 to 5.8. Four of these spots were confirmed to be BSP1 using mass spectrometry, proteomics, biochemical, and computational analysis (Tukey's test at P < 0.05). The protein spot weighing 15.52 ± 0.53 kDa with a pI value of 5.78 ± 0.12 is highlighted by its high abundance in bulls with low semen freezability and its absence in bulls presenting high semen freezability. This is the first report showing that more than two forms of BSP1 are found in the seminal plasma of Nelore adult bulls and not all animals have a similar abundance of each BSP1 form. Different BSP1 forms may be involved in different events of fertilization and the cryopreservation process.

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

“…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].…”

“…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].…”

“…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]. According to Sarsaii et al [22], approximately 52% of the SP protein spots detected after cryopreservation were represented by four major protein fractions with diferent molecular weights, and 10 proteins, identiied by mass spectrometry, were major bovine SP proteins.…”

“…Irrespective of the thawing procedure of frozen semen, it was reported that there was an increase in the expression levels of a few proteins, such as clusterin (CLU), histone H4 (HIST1H4A), and L-xylulose reductase (DCXR), whereas there was a decrease in the expression levels of several proteins, including apoptosis-inducing factor 1-mitochondrial (AIFM1), carbonic anhydrase 2 (CA2), acrosin (ACR), phosphoglycerate mutase 2 (PGAM2), inositol monophosphatase 1 (IMPA1), calmodulin (CALM1), cytochrome (CYC2), and NADH-cytochrome b5 reductase2 (CYB5R2) [43]. Besides the efect upon the sperm membrane protein P25b, an acrosome membrane-coating protein, cryopreservation causes a signiicant loss of several sperm-coating proteins, resulting in reduced post-thaw semen quality [10,[22][23][24][39][40][41][42][43][44][45]. It appears that the cryo-induced decrease in the levels of sperm proteins is probably atributed to protein degradation, membrane damage due to osmotic stress, and the subsequent freezing-thawing causing the elux of intracellular sperm constituents [6,43].…”

Sazonalidade e qualidade do sêmen fresco e criopreservado de touros Pantaneiro e Nelore

“…Animais submetido a altas temperaturas têm queda na fertilidade pois o seu parênquima testicular entra em um quadro de hipóxia e consequente degeneração, que por sua vez leva a maiores níveis de estresse oxidativo no ejaculado, aumento de defeitos espermáticos, queda na motilidade, entre outros (Nichi et al, 2006;Magalhães Jr et al, 2016).…”