Sperm proteomic changes associated with early embryo quality after ICSI.

RESEARCH QUESTION: Do alterations of human sperm protein profile affect embryo quality? DESIGN: Sperm proteins from 27 infertile couples undergoing intracytoplasmic sperm injection (ICSI) were extracted and digested. The resulting peptides were labelled using tandem mass tags, separated by two-dimensional liquid chromatography, and identified and quantified using tandem mass spectrometry. Subsequently, sperm protein and peptide abundance were statistically analysed for correlation with ICSI-derived embryo quality in the subset of idiopathic infertile couples. Detected correlations were further assessed in the subset of infertile patients with a known factor. RESULTS: The abundance of 18 individual sperm proteins was found to correlate with embryo quality after ICSI. Of note, a high percentage of poor-quality ICSI-derived embryos was associated with alterations in several components of the eight-membered chaperonin-containing T-complex, which plays an important role in the folding of many essential proteins. Additionally, the abundance of sperm proteins with known functions in embryogenesis, such as RUBVL1, also correlated with early embryo quality (r = -0.547; P = 0.028). Some of the correlations found in this study were validated using either proteomic data from infertile patients with a known factor or data from similar published studies. Analysis at the peptide level revealed the association of some correlations with specific post-translational modifications or isoforms. CONCLUSIONS: Our results support the hypothesis that the sperm proteome plays a role in early embryogenesis. Moreover, several sperm proteins have emerged as potential biomarkers that could predict the outcome of in-vitro assisted reproductive technologies, leading to the possibility of improved diagnosis of couples with idiopathic infertility.

Identification of proteins involved in human sperm motility using high-throughput differential proteomics.

Mammalian sperm motility is a prerequisite for in vivo fertilization, and alterations in this parameter are commonly observed in infertile males. However, we still do not have a complete understanding of the molecular mechanisms controlling it. The aim of this study was to identify proteins involved in human sperm motility deficiency by using TMT protein labeling and LC-MS/MS. Two complementary approaches were used: comparison between sperm samples differing in motility (asthenozoospermic versus normozoospermic) and comparison between sperm subpopulations of fractionated normozoospermic samples differing in motility (non-migrated versus migrated). LC-MS/MS resulted in the identification of 1157 and 887 proteins in the first and second approaches, respectively. Remarkably, similar proteomic alterations were detected in the two experiments, with 80 proteins differentially expressed in the two groups of samples and 93 differentially expressed in the two groups of subpopulations. The differential proteins were analyzed by GO, cellular pathways, and clustering analyses and resulted in the identification of core deregulated proteins and pathways associated with sperm motility dysfunction. These included proteins associated with energetic metabolism, protein folding/degradation, vesicle trafficking, and the cytoskeleton. Contrary to what is usually accepted, the outcomes support the hypothesis that several metabolic pathways (notably, mitochondrial-related ones) contribute toward regulating sperm motility.