Biomarkers Of Male Infertility Research Articles

Metabolic profiling putatively identifies plasma biomarkers of male infertility using UPLC-ESI-IT-TOFMS.

Male infertility has become a global health problem. Currently, the diagnosis of male infertility depends on the results of semen quality or requires invasive surgical intervention. The process is complex and time-consuming. Metabolomics is an emerging platform with unique advantages in disease diagnosis and pathological mechanism research. In this study, ultra-performance liquid chromatography-electrospray ionization-ion trap-time of flight mass spectrometry (UPLC-ESI-IT-TOFMS) combined with chemometrics methods was used to discover potential biomarkers of male infertility based on non-targeted plasma metabolomics. Plasma samples from healthy controls (HC, n = 43) and various types of infertile patients, i.e., patients having oligozoospermia (OS, n = 36), asthenospermia (AS, n = 56) and erectile dysfunction (ED, n = 45) were analyzed by UPLC-ESI-IT-TOFMS. Principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were performed. The results of OPLS-DA showed that HCs could be discriminated from infertile patients including OS (R2 = 0.903, Q2 = 0.617, AUC = 0.992), AS (R2 = 0.985, Q2 = 0.658, AUC = 0.999) or ED (R2 = 0.942, Q2 = 0.500, AUC = 0.998). Some potential biomarkers were successfully discovered by variable selection methods and variable important in the projection (VIP) in combination with the T-test. Statistical significance was set at p < 0.05; the Benjamini–Hochberg false discovery rate was used to reduce type 1 errors resulting from multiple comparisons. The identified biomarkers were associated with energy consumption, hormone regulation and antioxidant defenses in spermatogenesis. To elucidate the pathophysiology of male infertility, relative metabolic pathways were studied. It was found that male infertility is closely related to disturbed phospholipid metabolism, amino acid metabolism, steroid hormone biosynthesis metabolism, metabolism of fatty acids and products of carnitine acylation, and purine and pyrimidine metabolisms. Plasma metabolomics provides a novel strategy for the diagnosis of male infertility and offers a new insight to study pathogenesis mechanism.

Soluble protein fraction of human seminal plasma

Human seminal plasma (SP) is a complex fluid where sperm cells are bathed. Until recently, SP was simply retained a spermatozoa transport medium with nourishing functions. Growing evidences are nowadays recognizing it as a main actor “on the stage” of reproduction: SP orchestrates the synchronized cascade of events that make spermatozoa able to fertilize and modulates male and female reproductive fitness in physiological and in pathological states.Despite all SP studies have focused on “whole” SP or on its extracellular vesicles, to obtain an in-depth functional comprehension of SP, also the merely vesicle-free SP (vf-SP) soluble fraction deserves consideration. Here we present the first vf-SP functional proteomic study applying 2-DE, MALDI-TOF MS, and cluster and pathway analyses.Our work evidenced the occurrence of few unique proteins in vf-SP and an unexpected high heterogeneity of their corresponding protein species, conceivably derived by massive co- and/or post-translational modification events. Generated nets and clusters revealed tight functional correlations among identified proteins as well as their involvement in key functions for spermatozoa support and fertilization. Moreover, since SP is released by urogenital tissues and glands, our work may pave the way to the evaluation of vf-SP expression-profiles in diagnosing pathological processes in the secreting tissues. Biological significanceSeminal plasma vesicles are emerging as rich reservoirs of biomarkers for male infertility and urogenital disorders. Our proteomic approach to human SP diverges from the general trend in SP characterization, investigating not sperm extracellular vesicles but rather the vesicle-depleted SP fraction. Here we discussed how also SP soluble fraction may be considered actively involved in spermatozoa maturation, and we suggested that vf-SP protein profile may offer a precious overview on spermatogenesis, epididymal maturation, ancillary gland functionality, and sperm quality, thus highlighting its potentiality as a biomarker source in man health and reproduction.The present work provided the first 2-DE reference map of the so far underestimated vf-SP and an innovative and comprehensive functional-overview of its proteins. Obtained data may concur to clarify biochemical and molecular processes that the in fieri and the ejaculated semen undergoes as well as how semen properties can affect fertility or may reflect genital disorders.This paper is dedicated to the memory of Dr Riccardo Focarelli, associated professor in Comparative Anatomy and Glycobiology at the Dpt. of Life Sciences, Siena University, to acknowledge his fundamental contribution to the design of this study and in recognition of his distinguished research legacy.

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

Male infertility evaluation is mainly based on semen analysis. Thus, identification of additional diagnostic methods is valuable. The aim of this study was to analyse the sperm proteome of infertile men to identify the underlying mechanisms and reliable diagnostic biomarkers. This cross-sectional study consisted of 16 infertile men and seven proven fertile men. An LC-MS/MS approach was performed in five pooled samples of each group (proven fertile men, primary infertility and secondary infertility). Differentially expressed proteins were used for functional enrichment analyses, and the most central proteins involved in altered functions in both infertile groups and the testis-specific proteins were validated using Western blotting and immunocytochemistry. In total, 1,305 sperm proteins were identified, of which 102 were underexpressed and 15 were overexpressed proteins in both infertile groups. Underexpressed proteins were mostly related to protein post-translational modification and folding, especially BAG6, HSPA2 and SPA17. Validation analysis revealed an underexpression of BAG6 in infertile men, whereas HSPA2 and SPA17 expressions did not differ between the groups. No differences were observed in the sperm localisation of these proteins. An overexpression of HIST1H2BA-a testis-specific protein-was observed in both proteomic approaches. Therefore, BAG6 and HIST1H2BA are potential candidates for male infertility biomarkers.

Protamines ratio (P1/P2) in spermatozoa as biomarker for male infertility

Protamines ratio (P1/P2) in spermatozoa as biomarker for male infertility

Sperm DNA damage has a negative effect on early embryonic development following in vitro fertilization.

Sperm DNA damage is recognized as an important biomarker of male infertility. To investigate this, sperm DNA damage was assessed by the sperm chromatin dispersion (SCD) test in semen and motile spermatozoa harvested by combined density gradient centrifugation (DGC) and swim-up in 161 couples undergoing in vitro fertilization (IVF). Semen analysis and sperm DNA damage results were compared between couples who did or did not achieve pregnancy. The sperm DNA damage level was significantly different between the two groups (P < 0.05) and was negatively correlated with IVF outcomes. Logistic regression analysis confirmed that it was an independent predictor for achieving clinical pregnancy. The effects of different levels of sperm DNA damage on IVF outcomes were also compared. There were significant differences in day 3 embryo quality, blastocyst formation rate, and implantation and pregnancy rates (P < 0.05), but not in the basic fertilization rate between the two groups. Thus, sperm DNA damage as measured by the SCD appears useful for predicting the clinical pregnancy rate following IVF.

Systematic characterization of human testis-specific actin capping protein β3 as a possible biomarker for male infertility.

Is actin capping protein (CP) β3 involved in human spermatogenesis and male infertility? Human CPβ3 (hCPβ3) is expressed in testis, changes its localization dynamically during spermatogenesis, and has some association with male infertility. The testis-specific α subunit of CP (CPα3) was previously identified in human, and mutations in the cpα3 gene in mouse were shown to induce malformation of the sperm head and male infertility. However, CPβ3, which is considered to be a heterodimeric counterpart of CPα3, has been neither characterized in human nor reported in association with male infertility. To confirm the existence of CPβ3 in human testis, fresh semen samples from proven fertile men were analyzed. To investigate protein expression during spermatogenesis, cryopreserved testis obtained from men with obstructive azoospermia were examined by immunofluorescent analysis. To assess the association of CP with male infertility, we compared protein expression of human CPα3 (hCPα3) and hCPβ3 using immunofluorescent analysis of cryopreserved sperm between men with normozoospermia (volunteers: Normo group, n = 20) and infertile men with oligozoospermia and/or asthenozoospermia (O + A group, n = 21). The tissue-specific expression of hCPβ3 was investigated by RT-PCR and Western blot analysis. To investigate whether hCPα3 and hCPβ3 form a heterodimer, a tandem expression vector containing hcpα3 tagged with monomeric red fluorescent protein 1 and hcpβ3 tagged with enhanced green fluorescent protein in a single plasmid was constructed and analyzed by co-immunoprecipitation (Co-IP) assay. The protein expression profiles of hCPα3 and hCPβ3 during spermatogenesis were examined by immunohistochemical analysis using human spermatogenic cells. The protein expressions of hCPα3 and hCPβ3 in sperm were compared between the Normo and O + A groups by immunohistochemical analysis. RT-PCR showed that mRNA of hcpβ3 was expressed exclusively in testis. Western blot analysis detected hCPβ3 with anti-bovine CPβ3 antibody. Co-IP assay with recombinant protein showed that hCPα3 and hCPβ3 form a protein complex. At each step during spermatogenesis, the cellular localization of hCPβ3 changed dynamically. In spermatogonia, hCPβ3 showed a slight signal in cytoplasm. hCPβ3 expression was conspicuous mainly from spermatocytes, and hCPβ3 localization dynamically migrated from cytoplasm to the acrosomal cap and acrosome. In mature spermatozoa, hCPβ3 accumulated in the postacrosomal region and less so at the midpiece of the tail. Double-staining analysis revealed that hCPα3 localization was identical to hCPβ3 at every step in the spermatogenic cells. Most spermatozoa from the Normo group were stained homogenously by both hCPα3 and hCPβ3. In contrast, significantly more spermatozoa in the O + A versus Normo group showed heterogeneous or lack of staining for either hCPα3 or hCPβ3 (abnormal staining) (P < 0.001). The percentage of abnormal staining was higher in the O + A group (52.4 ± 3.0%) than in the Normo group (31.2 ± 2.5%). Even by confining the observations to morphologically normal spermatozoa selected in accordance with David's criteria, the percentage of abnormal staining was still higher in the O + A group (39.9 ± 2.9%) versus the Normo group (22.5 ± 2.1%) (P < 0.001). hCPβ3 in conjunction with hCPα3 seemed to play an important role in spermatogenesis and may be associated with male infertility. Not applicable. Owing to the difficulty of collecting fresh samples of human testis, we used cryopreserved samples from testicular sperm extraction. To examine the interaction of spermatogenic cells or localization in seminiferous tubules, fresh testis sample of healthy males are ideal. The altered expression of hCPα3 and hCPβ3 may not only be a cause of male infertility but also a prognostic factor for the results of ART. They may be useful biomarkers to determine the fertilization ability of human sperm in ART. This work was supported by a Grant-in-Aid for Young Scientists (B) from the Japan Society for the Promotion of Science (JP16K20133). The authors declare no competing interests.

Seminal biomarkers for the evaluation of male infertility.

For men struggling to conceive with their partners, diagnostic tools are limited and often consist of only a standard semen analysis. This baseline test serves as a crude estimation of male fertility, leaving patients and clinicians in need of additional diagnostic biomarkers. Seminal fluid contains the highest concentration of molecules from the male reproductive glands, therefore, this review focuses on current and novel seminal biomarkers in certain male infertility scenarios, including natural fertility, differentiating azoospermia etiologies, and predicting assisted reproductive technique success. Currently available tests include antisperm antibody assays, DNA fragmentation index, sperm fluorescence in situ hybridization, and other historical sperm functional tests. The poor diagnostic ability of current assays has led to continued efforts to find more predictive biomarkers. Emerging research in the fields of genomics, epigenetics, proteomics, transcriptomics, and metabolomics holds promise for the development of novel male infertility biomarkers. Seminal protein-based assays of TEX101, ECM1, and ACRV1 are already available or under final development for clinical use. Additional panels of DNA, RNA, proteins, or metabolites are being explored as we attempt to understand the pathophysiologic processes of male infertility. Future ventures will need to continue data integration and validation for the development of clinically useful infertility biomarkers to aid in male infertility diagnosis, treatment, and counseling.

Angiotensin II type 2 receptor is expressed in human sperm cells and is involved in sperm motility

To investigate the presence of angiotensin II type 2 receptor (AT2R) in human spermatozoa and its implication in sperm fertility status. We carried out expression assays for AT2R by reverse transcription-polymerase chain reaction, Western blot, immunofluorescence, and flow cytometry techniques in human sperm cells. Percentage of AT2R-positive sperm cells was analyzed by flow cytometry. Assisted reproduction unit and academic research laboratory. Ninety-seven human semen samples from the Clínica IVI Bilbao. All samples were examined and classified according to World Health Organization guidelines. Spermatozoa were isolated from semen on discontinuous colloidal silica gradient (45%-90%) and swim-up techniques. Presence and location of the AT2R in spermatozoa and percentage of AT2R-positive sperm cells measured by flow cytometry. We demonstrated the existence of AT2R and its transcript in human sperm by Western blot and reverse transcription-polymerase chain reaction. Immunofluorescence studies showed that AT2R is mainly located at the equatorial segment of the sperm head. The AT2R levels were associated with sperm motility parameters. Particularly, we found a significant positive correlation between AT2R and spermatozoa with progressive motility grade and a significant negative correlation with immotile spermatozoa, both in fresh semen samples and in prepared sperm cells. Regarding pathologic studies, the levels of AT2R measured by flow cytometry were lower in spermatozoa of asthenozoospermic men than in normozoospermic controls. Angiotensin II type 2 receptor is present in human semen and may be involved in the control of sperm motility. In-depth understanding of the proteins involved in sperm motility can help to elucidate the role of these proteins in male infertility as well as to establish new biomarkers for male infertility.

Immunocapture-Selected Reaction Monitoring Screening Facilitates the Development of ELISA for the Measurement of Native TEX101 in Biological Fluids*

Monoclonal antibodies that bind the native conformation of proteins are indispensable reagents for the development of immunoassays, production of therapeutic antibodies and delineating protein interaction networks by affinity purification-mass spectrometry. Antibodies generated against short peptides, protein fragments, or even full length recombinant proteins may not bind the native protein form in biological fluids, thus limiting their utility. Here, we report the application of immunocapture coupled with selected reaction monitoring measurements (immunocapture-SRM), in the rapid screening of hybridoma culture supernatants for monoclonal antibodies that bind the native protein conformation. We produced mouse monoclonal antibodies, which detect in human serum or seminal plasma the native form of the human testis-expressed sequence 101 (TEX101) protein-a recently proposed biomarker of male infertility. Pairing of two monoclonal antibodies against unique TEX101 epitopes led to the development of an ELISA for the measurement of TEX101 in seminal plasma (limit of detection: 20 pg/ml) and serum (limit of detection: 40 pg/ml). Measurements of matched seminal plasma samples, obtained from men pre- and post-vasectomy, confirmed the absolute diagnostic specificity and sensitivity of TEX101 for noninvasive identification of physical obstructions in the male reproductive tract. Measurement of male and female serum samples revealed undetectable levels of TEX101 in the systemic circulation of healthy individuals. Immunocapture-SRM screening may facilitate development of monoclonal antibodies and immunoassays against native forms of challenging protein targets.

High Quality RNA in Semen and Sperm: Isolation, Analysis and Potential Application in Clinical Testing

Male infertility is a complex health condition. To our knowledge there are no molecular biomarkers of male infertility. Sperm RNA is a potential biomarker for detecting sperm abnormalities and viability at infertility clinics. However, RNA use is hindered by its inconsistent quantity, quality, multiple cell types in semen and condensed sperm structure. We tested the usefulness of high quality RNA isolated from mature sperm and whole semen by our protocol, which reduces RNA degradation by maintaining semen and protocol components at 37 C and decreasing processing time. We isolated RNA from 83 whole semen samples, 18 samples of motile sperm prepared by the swim-up protocol and 18 of sperm prepared by the standard Percoll gradient method. Electrophoretic and spectral analysis of RNA revealed high quality 18S and 28S rRNAs in 71 of 83 whole semen samples (86%) and 15 of 18 mature sperm swim-up samples (83%). However, high quality RNA was isolated from only 7 of 18 Percoll gradient sperm samples (39%). Interestingly quantitative reverse transcriptase-polymerase chain reaction analysis of 4 somatic and 10 germ cell markers showed that whole semen and swim-up samples had similar RNA profiles. RNA sequencing revealed that most encoded proteins were involved in mature sperm function, regulation of DNA replication, transcription, translation, cell cycle and embryo development. We believe that semen and sperm specific RNAs are highly informative biomarkers for germ cell stages and somatic cell contribution. Therefore, these RNAs could be valuable diagnostic indicators of sperm survival, fertilization and early embryogenesis, and could serve as a predictor of the in vitro fertilization prognosis.

Seminal plasma as a diagnostic fluid for male reproductive system disorders

Molecular biomarkers hold promise to advance the noninvasive diagnosis of male reproductive system disorders and facilitate the identification and management of these conditions through screening, early diagnosis and more accurate prognosis. Seminal plasma has great potential as a proximal fluid for protein biomarker discovery and as a clinical sample for noninvasive diagnostics. The seminal plasma proteome contains thousands of proteins and includes a large number of tissue-specific proteins that might accurately indicate a pathological process in the tissue of origin. Potential protein biomarkers for male reproductive system disorders are more abundant in seminal plasma than in blood serum or urine, and, therefore, are more easily identified and quantified in semen by mass spectrometry and other techniques. These methods have enabled elaboration of the composition of the seminal plasma proteome and the tissue specificity of seminal plasma proteins. Strategies have been developed to discover protein biomarkers in seminal plasma through integrated 'omics' approaches. Biomarkers of male infertility and prostate cancer are now emerging, and it is evident that seminal plasma has the potential to complement other diagnostic tools available in urology clinics.

Expressions of miR-15a and its target gene HSPA1B in the spermatozoa of patients with varicocele

Hyperthermia and oxidative stresses are the two central elements contributing to varicocele-related sperm damage. Growing evidence indicates that microRNAs (miRNAs) are involved in the regulation of the heat and oxidative stress responses. In this study, we analyzed the expressions of several stress-related miRNAs in the sperm and found that the expression of miR-15a was significantly decreased in patients with varicocele compared with the control. Furthermore, miR-15a repressed the expression of HSPA1B, which is a typical stress-induced chaperone protein, through directly binding its 3'-UTR. The expressions of miR-15a and HSPA1B exhibited an inverse correlation in sperm. Our results provide a valuable insight into the varicocele-related sperm impairment and male infertility, and may help to develop potential therapeutic targets and novel biomarkers for male infertility.

Identification of microRNAs predominately derived from testis and epididymis in human seminal plasma

ObjectivesAiming to develop potential noninvasive biomarkers for male infertility, the present study is designed to identify cell-free seminal piRNAs (PIWI-interacting RNA), and microRNAs predominately derived from testis and epididymis in human semen, which is secreted from the male accessory reproductive organs. Design and methodsThe ejaculate of successfully vasectomized men does not contain any secretion from the testis or epididymis. We screened cell-free seminal piRNAs, and microRNAs that predominately derived from testis/epididymis by comparing Solexa sequencing of seminal RNA of normozoospermic donors and vasectomized men, followed by quantitative PCR validation in individuals. ResultsTotally 84 seminal microRNAs exhibited levels >4-fold higher in normozoospermic donors than in vasectomized men. Subsequent quantitative PCR validation in individuals confirmed 61 microRNAs predominately secreted from testis/epididymis. Of these miRNAs, the lowest level in normozoospermic donors is ≥2-fold (24 miRNAs) or 0–2-fold (37 miRNAs) more than the highest level in vasectomized men. Interestingly, 28 microRNAs, which contain 5 microRNA clusters (18 microRNAs), reside on the X-chromosome. Some microRNAs have been shown or predicted to target important genes in spermatogenesis or sperm maturation. At least 995 seminal piRNAs were identified in normozoospermic donors while were absent in vasectomized men. ConclusionsThe present study identified cell-free seminal piRNAs, and microRNAs that predominately derived from testis and epididymis. These small noncoding RNAs might be useful noninvasive epigenetic markers for human male infertility researches on revealing the etiology and physiopathological status of impaired sperm production and maturation.

Functional proteomic analysis of seminal plasma proteins in men with various semen parameters

BackgroundAlterations at the molecular level in spermatozoa and seminal plasma can affect male fertility. The objective of this study was to determine if analysis of differential expression of proteins in varying semen parameters can serve as potential biomarkers for male infertility.MethodsThe differential expression of proteins in the seminal plasma of men based on sperm count and morphology were examined utilizing proteomic tools. Subjects were categorized based on sperm concentration and morphology into 4 groups: 1) normal sperm count and normal morphology (NN); 2) normal sperm count and abnormal morphology (NA); 3) oligozoospermia and normal morphology (ON); and 4) oligozoospermia and abnormal morphology (OA). Proteomic analysis was performed by LC-MS/MS followed by functional bioinformatics analysis. Protein distribution in the NA, ON and OA groups was compared with that of the NN group.ResultsTwenty proteins were differentially expressed among the 4 groups. Among the unique proteins identified, 3 were downregulated in the NA group, 1 in the ON group and 1 in the OA group while 2 were upregulated in the ON and OA groups. The functional analysis 1) identified biological regulation as the major processes affected and 2) determined that most of the identified proteins were of extracellular origin.ConclusionsWe have identified proteins that are over-or underexpressed in the seminal plasma of men with poor sperm quality. The distinct presence of some of the proteins may serve as potential biomarkers and provide insight into the mechanistic role played by these proteins in male infertility. Further studies using Western Blot analysis are required to validate these findings.

Genome-wide promoter methylation profile of human testis and epididymis: identified from cell-free seminal DNA

BackgroundDNA methylation analysis is useful for investigation of male fertility in mammals, whereas the reliance on tissues limits the research on human. We have previously found the presence of high concentration of cell-free seminal DNA (cfsDNA) in human semen. We proposed that some testis and epididymis-specific methylated promoters could be detected in human cfsDNA, and thus hold promise as noninvasive epigenetic biomarkers for male infertility, of which most cases are caused by defects in testicular sperm production or epididymal sperm maturation.ResultsThe ejaculate of successfully vasectomized men does not contain any secretion from testis and epididymis. Here we compared genome-wide promoter methylation profiles in cfsDNA between health donors and post-vasectomy men. Promoters of 367 testis and epididymis-specific hypomethylated genes and 134 hypermethylated genes were identified. Subsequent validation by Methyl-DNA immunoprecipitation and MethyLight analysis confirmed the result of promoter microarray. Gene Ontology analysis revealed many genes involved in male reproduction.ConclusionWe detected the testis and epididymis-specific methylated promoters in human cfsDNA, which may be used for noninvasive epigenetic biomarkers for the study and diagnosis of male infertility.

Human Seminal Plasma Proteome Study: a Search for Male Infertility Biomarkers

Seminal plasma is a potential source of biomarkers for many disorders of the male reproductive system including male infertility. Knowledge of the peptide and protein components of seminal fluid is accumulating especially with the appearance of high-throughput MS-based techniques. Of special interest in the field of male infertility biomarkers, is the identification and characterization of differentially expressed proteins in seminal plasma of men with normal and impaired spermatogenesis. However, the data obtained until now is still quite heterogeneous and with small percentage of overlap between independent studies. Extensive comparative analysis of seminal plasma proteome is still needed in order to establish a potential link between seminal plasma proteins and male infertility.

Identification of genital tract markers in the human seminal plasma using an integrative genomics approach

Can protein biomarkers of the male genital tract be identified in human seminal plasma? We identified potential biomarkers for each of the organs participating in the secretions of the human seminal plasma. The seminal plasma fulfills critical functions for fertility by providing spermatozoa with a protective milieu, promoting their final maturation and modulating the immune responsiveness of the female reproductive tract. It is also considered to be a promising source of biomarkers of male infertility and/or pathologies of the male genital tract. This study combines proteomic analyses of normal seminal plasma together with transcriptomic gene expression profiling of human healthy tissues. Non-liquefied seminal plasma proteins from a healthy donor were prefractionated using two sequential Proteominer™ libraries. Eight subproteome fractions were collected, trypsin digested and subjected to three successive mass spectrometry analyses for peptide characterization. The list of identified proteins was compared with and merged with other available data sets of the human seminal plasma proteome. The expression of corresponding genes was then investigated using tissue transcriptome profiles to determine where, along the male reproductive tract, these proteins were produced. Finally, tissue specificity of a selected subset of biomarker candidates was validated on human tissues. We first performed a proteomic analysis of the human seminal plasma and identified 699 proteins. By comparing our protein list with other previous proteomic data sets, we found that 2545 unique proteins have been described so far in the human seminal plasma. We then profiled their expression at the gene level and identified 83 testis, 42 epididymis, 7 seminal vesicle and 17 prostate candidate protein markers. For a subset of testis-specific candidates, i.e. TKTL1, LDHC and PGK2, we further validated their germ cell expression and demonstrated that such markers could distinguish between semen from fertile and infertile men. While some of the markers we identified are well-known tissue-specific products, further dedicated studies to validate the biomarker status of new candidates will be required. Additionally, whether or not the abundance of these proteins is indeed decreased in some specific pathological situations remains to be determined. Using an integrative genomics approach, we identified biomarker candidates for each of the organs participating in the seminal plasma production. In this study, we essentially focused on germ cell markers and their potential application for the diagnosis of male infertility. Other types of markers also deserve a focused attention given their potential predictive value for various reproductive disorders, notably for prostate cancers. This work was supported by the Proteomics Core Facility at Biogenouest and was funded by Conseil Régional de Bretagne, IBiSA and Agence de la Biomédecine grants. The authors declare that there exists a competing financial interest in this work that is related to a patent application on the use of identified germ cell-specific proteins in an antibody-based assay (Fertichip™) to predict the successful testicular biopsy outcomes in human non-obstructive azoospermia.

P55 Nuclear organisation in spermatozoa, a potential biomarker for male infertility?

P55 Nuclear organisation in spermatozoa, a potential biomarker for male infertility?

The role of molecular chaperones in spermatogenesis and the post-testicular maturation of mammalian spermatozoa

Spermatogenesis culminates in production of one of the most highly differentiated cells in biology, the spermatozoon. The gametes that emerge from the testes are, however, functionally immature and only acquire full functionality once they have completed a process of post-testicular maturation in the epididymis and female reproductive tract. Remarkably, this acquisition of sperm function occurs while these cells are transcriptionally and translationally silent and is therefore highly dependent on post-translational modifications to their existing protein complement. In this review, we consider the emerging roles of several prominent molecular chaperone families in orchestrating both the morphological differentiation of male germ cells during spermatogenesis and their functional transformation during sperm maturation. Journal databases were searched using key words, including chaperone, heat shock protein, testes, spermatogenesis, spermatozoa, epididymal maturation, capacitation and fertilization. In the past two decades, molecular chaperones have been acknowledged to play key roles in controlling both the morphological transformation of germ cells during spermatogenesis and the post-testicular maturation of these cells as they transit the male and female reproductive tracts. Furthermore, there is mounting evidence that aberrant chaperone expression may be a major contributing factor to the defective sperm function seen in many cases of male infertility. Molecular chaperones are critically involved in all phases of sperm development. Targeted disruption of these proteins has the ability to arrest spermatogenesis, compromise sperm maturation and inhibit fertilization. These proteins therefore hold considerable promise as targets for novel contraceptive strategies and as diagnostic biomarkers for male infertility.

Differential proteomics of human seminal plasma: A potential target for searching male infertility marker proteins

The clinical fertility tests, available in the market, fail to define the exact cause of male infertility in almost half of the cases and point toward a crucial need of developing better ways of infertility investigations. The protein biomarkers may help us toward better understanding of unknown cases of male infertility that, in turn, can guide us to find better therapeutic solutions. Many clinical attempts have been made to identify biomarkers of male infertility in sperm proteome but only few studies have targeted seminal plasma. Human seminal plasma is a rich source of proteins that are essentially required for development of sperm and successful fertilization. This viewpoint article highlights the importance of human seminal plasma proteome in reproductive physiology and suggests that differential proteomics integrated with functional analysis may help us in searching potential biomarkers of male infertility.