The rat sperm proteome characterized via IPG strip prefractionation and LC‐MS/MS identification

Abstract

Proteomics represents a powerful tool for the analysis of mammalian spermatozoa, since these terminally differentiated cells are transcriptionally inactive and exhibit a limited dynamic range of protein expression. Here we report the identification of 5123 peptides, leading to 829 unambiguous and 2215 redundant gene products found to be present within rat spermatozoa derived from the cauda epididymis. Bioinformatics demonstrated that 60 proteins appeared to be specifically expressed in the genitourinary tract, including pyruvate dehydrogenase 1, ropporin, testis-specific serine kinase 4, testis-specific transporter, and retinol dehydrogenase 14. We also identified eight members of the ADAM family, seven of which have previously been detected in spermatozoa (ADAM2, -3, -4, -5, -6, -7, and -30) while ADAM34 has been identified in the sperm proteome for the first time. Approximately 21 gene products were found to possess isomerase activity including peptidylprolyl cis/trans isomerases that are known to be involved in germ cell differentiation and protein disulfide isomerases that have been implicated in sperm-oocyte fusion. Furthermore, 51 gene products clustered into ion-transporter activity. This inventory of gene products, the first ever 2-D LC-MS/MS analysis of rat spermatozoa, will be invaluable in directing future research into the molecular mechanisms that drive these highly specialized cells.

Effects of Lunasia amara Blanco (Sanrego) on Male Fertility: A Preliminary Study on Sperm Proteomic Analysis

“…During fertilization, asparaginase plays a role in the glycosylation of ZP3 protein, which refers to a sperm receptor involved in sperm-oocyte binding. ZP3 will then induce the acrosomal reaction that enables the sperm plasma membrane to fuse with oolema (Baker et al, 2008). These findings signify that the improved fertility of sanrego-treated rats could also be due to the increased expression of Sp17 and asparaginase proteins.…”

“…The level of sperm motility required in the female reproductive tract is determined by ODF2, PGK2, LDHC, DNAJB13, Sp17, and tubulin. As the sperm comes in contact with zona pellucida, asparaginase has a significant function in the formation of glycoprotein needed for sperm-zona pellucida binding (Baker et al, 2008). Other than that, Sp17 is crucial in acrosomal reaction and membrane fusion between sperm and oocyte.…”

The ’omics revolution and our understanding of sperm cell biology

“…The answer may lie in the proteomic analysis of the rat sperm cells. 27 Herein, a non-redundant peptide hit (i.e., a peptide that only matches to one isoform), was found for the catalytic subunit of PKAb. Hence, it is tempting to speculate that while the PKAa global knockout produced sperm that were essentially immotile, this is more likely a developmental defect, rather than the involvement of any of the PKAa isoforms in motility activation per se.…”

“…Since the addition of anti-HSP60 or -HSP90 antibodies did not inhibit sperm-zona pellucida binding, the authors have speculated that HSPs on the sperm surface are involved in formation of a complex, which is ultimately responsible for zona pellucida interaction. 35 Apart from the human, other large scale studies utilizing LC-MS have been performed on rat 27 mouse, 26 bull 36 and fruit fly 37 sperm cells. An analysis of the 'common' proteins present within these species (common being found in at least two species) has been performed.…”

“…26 Furthermore, HSP60 has been detected in other species. 19,26,27 Why do sperm carry around so many HSPs within their proteome? And, as is the case for HSP70 and HSP90, why are they expressed at such high levels?…”