Human Sperm Tail Proteome Suggests New Endogenous Metabolic Pathways

Abstract

Proteomic studies are contributing greatly to our understanding of the sperm cell, and more detailed descriptions are expected to clarify additional cellular and molecular sperm attributes. The aim of this study was to characterize the subcellular proteome of the human sperm tail and, hopefully, identify less concentrated proteins (not found in whole cell proteome studies). Specifically, we were interested in characterizing the sperm metabolic proteome and gaining new insights into the sperm metabolism issue. Sperm were isolated from normozoospermic semen samples and depleted of any contaminating leukocytes. Tail fractions were obtained by means of sonication followed by sucrose-gradient ultracentrifugation, and their purity was confirmed via various techniques. Liquid chromatography and tandem mass spectrometry of isolated sperm tail peptides resulted in the identification of 1049 proteins, more than half of which had not been previously described in human sperm. The categorization of proteins according to their function revealed two main groups: proteins related to metabolism and energy production (26%), and proteins related to sperm tail structure and motility (11%). Interestingly, a great proportion of the metabolic proteome (24%) comprised enzymes involved in lipid metabolism, including enzymes for mitochondrial beta-oxidation. Unexpectedly, we also identified various peroxisomal proteins, some of which are known to be involved in the oxidation of very long chain fatty acids. Analysis of our data using Reactome suggests that both mitochondrial and peroxisomal pathways might indeed be active in sperm, and that the use of fatty acids as fuel might be more preponderant than previously thought. In addition, incubation of sperm with the fatty acid oxidation inhibitor etomoxir resulted in a significant decrease in sperm motility. Contradicting a common concept in the literature, we suggest that the male gamete might have the capacity to obtain energy from endogenous pools, and thus to adapt to putative exogenous fluctuations. Molecular &

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

“…In their recent proteomic studies of sperm, Baker et al (2013) and Amaral et al(2013) identified the proteins belonging to normal sperm head and tail domains [14,19].…”

“…The strong correlation between progressively motile spermatozoa and IVF success rates is well-proven [13]. A recent study on human sperm proteome demonstrated that some proteins of sperm tail could potentially contribute to embryo quality [14].…”

Unraveling the sperm proteome and post-genomic pathways associated with sperm nuclear DNA fragmentation

“…Triacylglycerols are a source of fatty acids, which are also important for sperm metabolism [70,71]. Amaral et al [72] have shown the association between the inhibition of a variety of enzymes involved with fatty acid beta oxidation and decreased human sperm motility, demonstrating its importance to sperm motility. In our study, the conserved protein Glyceraldehyde-3-Phosphate Dehydrogenase, testis-specific (GAPDHS), a glycolytic enzyme of the fibrous sheath involved with sperm motility [73], was involved with this function, in addition to spermatid development.…”

Identification of endogenous metabolites in human sperm cells using proton nuclear magnetic resonance (1H-NMR) spectroscopy and gas chromatography-mass spectrometry (GC-MS)

“…The identification of the metabolites and proteins as main determinants of the expression of the genomes and transcriptomes as also influenced by environmental cues, represents a first step to understand the normal composition and physiology of cells and tissues and their dysfunction associated with pathological states (Jodar et al, 2012;Wishart et al, 2013;Castillo et al, 2014a,b). In the case of the human spermatozoon, over 6000 proteins have been identified using mass spectrometry (MS), representing about 80% of the estimated proteome of this cell (Oliva et al, , 2009Amaral et al, 2013Amaral et al, , 2014aBaker et al, 2013;Azpiazu et al, 2014). However, and in *Correction added on 26 May 2015, after first online publication: article title corrected.…”