ABSTRACT
Male factors account for 40% of infertility cases. The identification of differentially expressed proteins on spermatozoa from fertile and infertile men can help in the elucidation of the molecular basis of male infertility. The aim of this study was to compare sperm proteomes from 3 different groups: fertile men, normozoospermic men consulting for infertility, and normozoospermic men with an impaired capacity for fertilization (IVF-failure). We used differential proteomics with isobaric tags for relative and absolute quantitation (iTRAQ) labeling, and LC-MS analysis to identify proteins that are differentially expressed. A total of 348 unique proteins were identified and quantified. The analysis identified 33 proteins that were differentially expressed in the IVF-failure group vs the fertile group. Comparison of the infertile and fertile groups revealed that 18 proteins appeared to be differentially expressed. Four proteins were similarly altered in the IVF-failure and infertile groups: semenogelin 1 (SEMG1), prolactin-induced protein (PIP), glyceraldehyde-3-phosphate dehydrogenase (GAPDHS), and phosphoglycerate kinase 2 (PGK2). These protein markers were selected for validation using multiple reactions monitoring mass spectrometry (MRM-MS) and further confirmed by Western blot analysis. Overall, these results suggest that a panel of proteins may be used as biomarkers for future studies of infertility.
Subject(s)
Infertility, Male/metabolism , Proteome/metabolism , Proteomics/methods , Spermatozoa/metabolism , Biomarkers/metabolism , Blotting, Western , Carrier Proteins/metabolism , Chromatography, Liquid , Glyceraldehyde-3-Phosphate Dehydrogenases/metabolism , Glycoproteins/metabolism , Humans , Infertility, Male/diagnosis , Isoenzymes/metabolism , Isotope Labeling/methods , Male , Mass Spectrometry , Membrane Transport Proteins , Phosphoglycerate Kinase/metabolism , Protein Interaction Maps , Seminal Vesicle Secretory Proteins/metabolismABSTRACT
OBJECTIVE: To investigate the presence of cysteine-rich secretory protein 1 (CRISP1) in seminal plasma as a means of distinguishing between obstructive azoospermia (OA) and nonobstructive azoospermia (NOA). DESIGN: Seminal plasma from normospermic donors (n = 45) and azoospermic donors (n = 80) was examined to determine CRISP1 levels. Neutral alpha-glucosidase (NAG) enzymatic activity was measured for comparison with CRISP1 levels. SETTING: Research unit of an academic medical center. PATIENT(S): Normospermic and azoospermic donors from the clinical andrology laboratory of the centre hospitalier universitaire de Québec and from Mount Sinai Hospital. INTERVENTION(S): Seminal CRISP1 measurement by Western blot analysis. Neutral alpha-glucosidase activity was evaluated by a photometric method. MAIN OUTCOME MEASURE(S): Seminal plasma CRISP1 levels, NAG activity, cutoff value, sensitivity, and specificity. RESULT(S): All seminal plasma samples from normospermic and nonobstructive azoospermic donors were CRISP1 positive, whereas CRISP1 was absent or present at low levels in samples from patients with OA. A significant correlation between seminal CRISP1 levels and NAG activity was found in azoospermic semen samples. The cutoff point to distinguish between donors with NOA or OA was established at 0.655 (relative intensity). At this threshold, specificity was 85% and sensitivity was 92%. CONCLUSION(S): Seminal CRISP1 combined with NAG activity can potentially distinguish between OA and NOA.
