Major protein alterations in spermatozoa from infertile men with unilateral varicocele

Abstract

BackgroundThe etiology of varicocele, a common cause of male factor infertility, remains unclear. Proteomic changes responsible for the underlying pathology of unilateral varicocele have not been evaluated. The objective of this prospective study was to employ proteomic techniques and bioinformatic tools to identify and analyze proteins of interest in infertile men with unilateral varicocele.MethodsSpermatozoa from infertile men with unilateral varicocele (n = 5) and from fertile men (control; n = 5) were pooled in two groups respectively. Proteins were extracted and separated by 1-D SDS-PAGE. Bands were digested and identified on a LTQ-Orbitrap Elite hybrid mass spectrometer system. Bioinformatic analysis identified the pathways and functions of the differentially expressed proteins (DEP).ResultsSperm concentration, motility and morphology were lower, and reactive oxygen species levels were higher in unilateral varicocele patients compared to healthy controls. The total number of proteins identified were 1055, 1010 and 1042 in the fertile group, and 795, 713 and 763 proteins in the unilateral varicocele group. Of the 369 DEP between both groups, 120 proteins were unique to the fertile group and 38 proteins were unique to the unilateral varicocele group. Compared to the control group, 114 proteins were overexpressed while 97 proteins were underexpressed in the unilateral varicocele group. We have identified 29 proteins of interest that are involved in spermatogenesis and other fundamental reproductive events such as sperm maturation, acquisition of sperm motility, hyperactivation, capacitation, acrosome reaction and fertilization. The major functional pathways of the 359 DEP related to the unilateral varicocele group involve metabolism, disease, immune system, gene expression, signal transduction and apoptosis. Functional annotations showed that unilateral varicocele mostly affected small molecule biochemistry and post-translational modification proteins. Proteins expressed uniquely in the unilateral varicocele group were cysteine-rich secretory protein 2 precursor (CRISP2) and arginase-2 (ARG2).ConclusionsThe expression of these proteins of interest are altered and possibly functionally compromised in infertile men with unilateral varicocele. If validated, these proteins may lead to potential biomarker(s) and help better understand the mechanism involved in the pathophysiology of unilateral varicocele in infertile men.Electronic supplementary materialThe online version of this article (doi:10.1186/s12958-015-0007-2) contains supplementary material, which is available to authorized users.

Towards the identification of reliable sperm biomarkers for male infertility: A sperm proteomic approach

“…Thus, the overall underexpression of sperm proteins related to PTM and folding in men with primary and secondary infertility may indicate an alteration in these processes in male infertility, but more studies are needed to confirm this finding. Similar results were also observed in infertile men with varicocele (Agarwal, Sharma, Durairajanayagam, Ayaz, et al., ; Agarwal, Sharma, Durairajanayagam, Cui, et al., ), asthenozoospermia (Amaral et al., ; Siva et al., ) and sperm DNA fragmentation (Intasqui et al., ), corroborating our data. Of all the proteins related to protein PTM and folding, HSPA2, BAG6 and SPA17 were selected for validation due to their central role in these pathways.…”

“…It has been hypothesised that the sperm protein profile in infertile men is altered, and some researchers have assessed these profiles in several male infertility conditions including varicocele (Agarwal, Sharma, Samanta, Durairajanayagam, & Sabanegh, ; Agarwal, Sharma, Durairajanayagam, Ayaz, et al., ; Agarwal, Sharma, Durairajanayagam, et al., ; Hosseinifar et al., ), obesity (Kriegel et al., ; Liu et al., ), smoking (Chen et al., ), failed fertilisation after assisted reproduction techniques (ART; Frapsauce et al., ; Legare et al., ; Pixton et al., ), asthenozoospermia (Amaral et al., ; Hashemitabar, Sabbagh, Orazizadeh, Ghadiri, & Bahmanzadeh, ; Liu et al., ; Martinez‐Heredia, de Mateo, Vidal‐Taboada, Ballesca, & Oliva, ; Parte et al., ; Shen, Wang, Liang, & He, ; Siva et al., ; Zhao et al., ) and idiopathic infertility (Legare et al., ; McReynolds et al., ; Xu et al., ). Sperm protein profiles have also been evaluated in men with semen oxidative stress (Ayaz et al., ; Sharma et al., ) and sperm DNA fragmentation (Intasqui et al., ; de Mateo et al., ), which are common causes of male infertility.…”

Sperm and Seminal Plasma Proteomics: Molecular Changes Associated with Varicocele-Mediated Male Infertility

“…Acetylation-associated proteins involved in fertilization and acrosome reaction (TALDO1: transaldolase 1, HIST1H2B: histone cluster 1 H2B family mem-ber B, GNPDA1: glucosamine-6-phosphate isomerase 1), apoptosis and DNA damage (HSP90AB1: heat shock protein 90 alpha family class B member 1, PPP5C: protein phosphatase 5 catalytic subunit, RUVBL: RuvBlike proteins), mitochondrial dysfunction and oxidative stress (SDHA: succinate dehydrogenase, PRDX1: peroxiredoxin 1 and GSHR: glutathione reductase) have been proposed as post-translational protein biomarkers in varicocele patients [62]. The list of potential sperm biomarkers in varicocele patients based on fertilization, motility and morphology, DNA damage, oxidative stress, and mitochondrial dysfunction are presented in Table 1 [25,26,54,57,58,[60][61][62][63][64][65][66][67].…”

Sperm RNA elements as markers of health

“…The discovery of ODF2 as a hub essential SRE is significant, because homo-and heterozygous knockout animal models of ODF2 result in preimplantation lethality and defects in sperm tail development, respectively [Lee 2012;Salmon et al 2006]. Altered ODF2 levels have been observed in other human male reproductive diseases, including globozoospermia and unilateral varicocele [Agarwal et al 2015b;Liao et al 2009]. The ODF2 protein is currently being validated as a sperm biomarker of male fertility or infertility [Agarwal et al 2016].…”

“…it is already a biomarker for other male reproductive diseases [Agarwal et al 2015b;Liao et al 2009]. GO enrichment of transcripts correlated with the three hub transcripts revealed terms associated with mature sperm, including acetylation, exosomes, and RNA binding.…”