BackgroundThe molecular mechanisms implicated in regionalized gene expression in the human epididymis have not yet been fully elucidated. Interestingly, more than 200 microRNAs (miRNAs) have been identified in the human epididymis and could be involved in the regulation of mRNA stability and post-transcriptional expression in this organ.MethodsUsing a miRNA microarray approach, we investigated the correlation between miRNA signatures and gene expression profiles found in three distinct regions (caput, corpus and cauda) of human epididymides from 3 donors. In silico prediction of transcript miRNA targets was performed using TargetScan and Miranda software's. FHCE1 immortalized epididymal cell lines were cotransfected with mimic microRNAs and plasmid constructs containing the 3′UTR of predicted target genes downstream of the luciferase gene.ResultsWe identified 35 miRNAs differentially expressed in the distinct segments of the epididymis (fold change ≥2, P-value≤0.01). Among these miRNAs, miR-890, miR-892a, miR-892b, miR-891a, miR-891b belonging to the same epididymis-enriched cluster located on the X chromosome, are significantly more expressed in the corpus and cauda regions than in the caput. Interestingly, a strong negative correlation (r = −0,89, P-value≤0.001) was found between the pattern of expression of miR-892b and its potential mRNA target Esrrg (Estrogen Related Receptor Gamma) and with miR-145 and Cldn10 mRNA (r = −0,92, P-value≤0.001). We confirmed that miR-145 and miR-892b inhibit the expression of the luciferase reporter via Cldn10 and Esrrg 3′ UTRs, respectively.ConclusionOur study shows that the expression of miRNAs is segmented along the human epididymis and correlates with the pattern of target gene expression in different regions. Therefore, epididymal miRNAs may be in control of the maintenance of gene expression profile in the epididymis, which dictates segment-specific secretion of proteins and establishes physiological compartments that directly or indirectly affect sperm maturation and fertility.

BackgroundTEX101 is a cell membrane protein exclusively expressed by testicular germ cells and shed into seminal plasma. We previously verified human TEX101 as a biomarker for the differential diagnosis of azoospermia, and developed a first-of-its-kind TEX101 ELISA. To demonstrate the clinical utility of TEX101, in this work we aimed at evaluating ELISA performance in a large population of fertile, subfertile, and infertile men.MethodsMass spectrometry, size-exclusion chromatography, ultracentrifugation, and immunohistochemistry were used to characterize TEX101 protein as an analyte in seminal plasma. Using the optimized protocol for seminal plasma pretreatment, TEX101 was measured by ELISA in 805 seminal plasma samples.ResultsWe demonstrated that TEX101 was present in seminal plasma mostly in a free soluble form and that its small fraction was associated with seminal microvesicles. TEX101 median values were estimated in healthy, fertile pre-vasectomy men (5436 ng/mL, N = 64) and in patients with unexplained infertility (4967 ng/mL, N = 277), oligospermia (450 ng/mL, N = 270), and azoospermia (0.5 ng/mL, N = 137). Fertile post-vasectomy men (N = 57) and patients with Sertoli cell-only syndrome (N = 13) and obstructive azoospermia (N = 36) had undetectable levels of TEX101 (≤0.5 ng/mL). A cut-off value of 0.9 ng/mL provided 100% sensitivity at 100% specificity for distinguishing pre- and post-vasectomy men. The combination of a concentration of TEX101 > 0.9 ng/mL and epididymis-specific protein ECM1 > 2.3 μg/mL provided 81% sensitivity at 100% specificity for differentiating between non-obstructive and obstructive azoospermia, thus eliminating the majority of diagnostic testicular biopsies. In addition, a cut-off value of ≥0.6 ng/mL provided 73% sensitivity at 64% specificity for predicting sperm or spermatid retrieval in patients with non-obstructive azoospermia.ConclusionsWe demonstrated the clinical utility of TEX101 ELISA as a test to evaluate vasectomy success, to stratify azoospermia forms, and to better select patients for sperm retrieval.Electronic supplementary materialThe online version of this article (doi:10.1186/s12916-017-0817-5) contains supplementary material, which is available to authorized users.

Background: The epididymis is the hallmark of all vertebrate species practicing internal fertilization. While the functions of the epididymis are well documented in laboratory rodents and some domestic animals, the structure and functions of the epididymis in humans remain poorly documented. Objectives: Using human tissues obtained with the collaboration of our local organ transplantation program, the histology, cell types, and three-dimensional organization of the excurrent duct were investigated. Microarrays were performed to determine the gene expression pattern along the human epididymis. Materials and methods: The histology of longitudinal sections of the proximal epididymis was described, and immunohistochemistry using specific antibodies was used to characterize cell types of the efferent duct and caput epididymis epithelia. The epididymis was divided into eight segments permitting gene profiling by microarray and gene ontology analysis. Results: The proximal region of the human epididymis is formed exclusively by efferent ducts. These ducts form a complex histological structure particularly at the junction of the efferent ducts and caput epididymis. The efferent ducts exhibit a specific cellular signature when compared with the adjacent epididymis tubule. Efferent duct gene expression is not segmented and is dedicated to cilium differentiation and movement. The gene expression pattern of the caput segment is homogeneous and specialized in defense and immune responses and fertilization. Discussion: In murine species, the epididymis is segmented into the initial segment, caput, corpus, and cauda regions, whereas in humans, the proximal region is formed by efferent ducts. The caput tubules have their own histological organization with a welldefined gene expression pattern. The distal corpus and cauda epididymis are distinct by a limited number of differentially expressed genes. Conclusions: Knowledge of epididymis functions and structure obtained using laboratory species should be extrapolated to humans with caution.

According to the critical role played by miRNAs in all biological systems, we believe that miRNA changes occurring upstream and downstream of the vasectomy site may be related to the reduced fertility outcome reported following surgically successful vasectomy reversal. This study may provide new tools for predicting vasovasostomy success and open avenues for the identification of the molecular players involved in male infertility.