Dataset Information

Buffalo sperm surface proteome profiling reveals an intricate relationship between innate immunity and reproduction.

ABSTRACT:

Background

Low conception rate (CR) despite insemination with morphologically normal spermatozoa is a common reproductive restraint that limits buffalo productivity. This accounts for a significant loss to the farmers and the dairy industry, especially in agriculture-based economies. The immune-related proteins on the sperm surface are known to regulate fertility by assisting the spermatozoa in their survival and performance in the female reproductive tract (FRT). Regardless of their importance, very few studies have specifically catalogued the buffalo sperm surface proteome. The study was designed to determine the identity of sperm surface proteins and to ascertain if the epididymal expressed beta-defensins (BDs), implicated in male fertility, are translated and applied onto buffalo sperm surface along with other immune-related proteins.

Results

The raw mass spectra data searched against an in-house generated proteome database from UniProt using Comet search engine identified more than 300 proteins on the ejaculated buffalo sperm surface which were bound either by non-covalent (ionic) interactions or by a glycosylphosphatidylinositol (GPI) anchor. The singular enrichment analysis (SEA) revealed that most of these proteins were extracellular with varied binding activities and were involved in either immune or reproductive processes. Flow cytometry using six FITC-labelled lectins confirmed the prediction of glycosylation of these proteins. Several beta-defensins (BDs), the anti-microbial peptides including the BuBD-129 and 126 were also identified amongst other buffalo sperm surface proteins. The presence of these proteins was subsequently confirmed by RT-qPCR, immunofluorescence and in vitro fertilization (IVF) experiments.

Conclusions

The surface of the buffalo spermatozoa is heavily glycosylated because of the epididymal secreted (glyco) proteins like BDs and the GPI-anchored proteins (GPI-APs). The glycosylation pattern of buffalo sperm-surface, however, could be perturbed in the presence of elevated salt concentration or incubation with PI-PLC. The identification of numerous BDs on the sperm surface strengthens our hypothesis that the buffalo BDs (BuBDs) assist the spermatozoa either in their survival or in performance in the FRT. Our results suggest that BuBD-129 is a sperm-surface BD that could have a role in buffalo sperm function. Further studies elucidating its exact physiological function are required to better understand its role in the regulation of male fertility.

SUBMITTER: Batra V

PROVIDER: S-EPMC8235841 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Male factors account for approximately 40% of all infertility. Conventional semen analysis focus on seminal physicochemical property and spermatozoa morphology. They yield no information concerning the functional competence of the spermatozoa(Petrunkina et al., 2007). Owning to the essential role of proteins in the reproductive process, comprehensive and systematic identification of proteome is critical to gain new insights into spermatogenesis and infertility. Recent advances in mass spectrometry have allowed the identification of hundreds to thousands of protein in spermatozoa(Oliva et al., 2008; Amaral et al., 2014; Codina et al., 2015). In major domestic mammalian species, global spermatozoa proteomic profiles have been described in rodents(Baker et al., 2008a; Baker et al., 2008b) and bovine(Peddinti et al., 2008). Meanwhile, lacking of new protein synthesis in spermatozoa supports the current view that the regulation of sperm maturation is controlled by exogenous proteins(O'Rand et al., 2011) (e.g., during epididymal transit). Among the seminal plasma proteins, The human seminal plasma has been comprehensively described (Pilch and Mann, 2006; Batruch et al., 2011; Milardi et al., 2012; Milardi et al., 2013; Sharma et al., 2013). In domestic animal species, some studies performing a systematic analysis on using high throughput proteomics have been performed(Kelly et al., 2006; Moura et al., 2007; Souza et al., 2012; Druart et al., 2013; Soleilhavoup et al., 2014). Buffalos (Bubalus bubalis) are adapted to hot–humid tropical climatic conditions, but have low reproductive efficiency. The low sperm motility maybe contributed to protein components variation of spermatozoa and seminal plasma. The composition of buffalo spermatozoa and buffalo seminal plasma (BSP) remains unknown. Proteomic study would be beneficial to the elucidation of the roles of sperm and BSP proteins in regulation of maturation, motility and fertilization. As such, the aim of the current study was to extensively characterize the differentially expressed protein of buffalo spermatozoa and seminal plasma using a comparative proteomics.