Proteomics-based study on asthenozoospermia: differential expression of proteasome alpha complex

Abstract

With a view to understand the molecular basis of sperm motility, we have tried to establish the human sperm proteome by two-dimensional PAGE MALDI MS/MS analysis. We report identification of 75 different proteins in the human spermatozoa. Comparative proteome analysis was carried out for asthenozoospermic and normozoospermic patients to understand the molecular basis of sperm motility. Analysis revealed eight proteins (including one unidentified) with altered intensity between the groups. Differential proteins distributed into three functional groups: 'energy and metabolism' (triose-phosphate isomerase, glycerol kinase 2, testis specific isoform and succinyl-CoA:3-ketoacid co-enzyme A transferase 1, mitochondrial precursor); 'movement and organization' (tubulin beta 2C and tektin 1) and 'protein turnover, folding and stress response' (proteasome alpha 3 subunit and heat shock-related 70 kDa protein 2). It was interesting to note that although the proteins falling in the functional group of 'energy and metabolism' are higher in the asthenozoospermic patients, the other two functional groups contain proteins, which are higher in the normozoospermic samples. Validation of results carried out for proteasome alpha 3 subunit by immunoblotting and confocal microscopy, confirmed significant changes in intensity of proteasome alpha 3 subunit in asthenozoospermic samples when compared with normozoospermic controls. Significant positive correlation too was found between proteasome alpha 3 subunit levels and rapid, linear progressive motility of the spermatozoa. In our understanding, this data would contribute appreciably to the presently limited information available about the proteins implicated in human sperm motility.

A multi-faceted approach to understanding male infertility: gene mutations, molecular defects and assisted reproductive techniques (ART)

“…Thacker et al, [217], found that four unique proteins including semenogelin II precursor, prolactin-induced protein, clusterin isoform 1, and PSA isoform 1 preproprotein were predominantly present in the semen of healthy men. In another study based on 2D SDS-PAGE followed by MALDI MS/MS analysis, Siva et al, [214] confirmed significant changes in intensity of proteasome alpha-3 subunit in asthenozoospermic samples when compared with normozoospermic controls. Significant positive correlation was found between proteasome alpha-3 subunit levels and rapid, linear progressive motility of the spermatozoa.…”

“…Approximately 403 different proteins have also been identified from the isolated sperm nuclei, the most prominent among them being the histones. Majority of sperm proteins have been functionally categorized as those involved in sperm movement and structural organization (34 %), energy and metabolism (27 %), stress response, protein folding and protein turnover (22 %), signaling and transport (8 %) and antioxidant activity (6 %) [214]. The others are essential in the capacitation of the spermatozoa, modulation of the immune responses in the uterus, formation of the tubal sperm reservoir and finally in both the sperm-zona pellucida (ZP) interaction and sperm and egg fusion.…”

Proteomics of spermatogenesis: from protein lists to understanding the regulation of male fertility and infertility

“…49 Among these findings, those relating to triosephosphate isomerase were recently validated by Siva et al. 50 Their study used the same strategy to analyse differentially expressed proteins in asthenozoospermic patients, and eight proteins with higher triosephosphate isomerase were identified in patients. We propose that in the case of reduced motile sperm, the overexpression of this enzyme may have been a compensatory reaction.…”

“…In the other studies, 50,51 asthenozoospermic samples were defined as those with 25% progressive motility (grade A) or 50% motile sperm (grades A1B). The samples in our study 49 were from patients with severe asthenozoospermia, and we think that the proteins identified represent clinically relevant molecular targets for sperm motility that will provide a better understanding of male infertility.…”

A proteomic analysis on human sperm tail: comparison between normozoospermia and asthenozoospermia

“…Proteins related to sperm function have been categorized into five groups: 1) sperm movement and structural organization; 2) energy and metabolism; 3) stress response and turn over proteins; 4) signaling and transport proteins; and 5) proteins with antioxidant activity [9]. The altered amounts of these proteins are involved in infertility conditions such as globozoospermia (round-headed sperm) [10], varicocele [11], and oligozoospermia [12].…”