Possible germ cell-Sertoli cell interactions are critical for establishing appropriate expression levels for the Sertoli cell-specific MicroRNA, miR-202-5p, in human testis

Background: To examine human microRNA expression in fertile men and subsequently to compare expression patterns of miRNAs in fertile and infertile men, specifically men with Sertoli Cell Only (SCO) histopathology. Methods: Testicular tissues from men with azoospermia and SCO, as well as those of men with normal spermatogenesis, were analyzed. MicroRNA was isolated using the miRCURY (TM) RNA Purification Kit. A miRCURY LNA (TM) Universal RT system was used for detection of microRNA by quantitative real-time PCR. MicroRNA localization was performed by in situ hybridizations (ISH) on formalin-fixed paraffin embedded (FFPE) tissue utilizing miRCURY LNA (TM) microRNA ISH technology. Statistical analysis was performed by GenEx V5.0. Results: MicroRNA expression was determined for 13 normal fertile men and 5 men with the confirmed diagnosis of diffuse SCO. MiR-202-5p expression was reduced by 17-fold (P < 0.00001) in tissue from SCO men compared to normal. MiR-34c-5p was reduced by 346-fold (P < 0.00001), miR-10b was reduced 18-fold (P < 0.00001), miR-191 was reduced 20-fold (P = 0.001) and miR-126 was reduced 40-fold (P < 0.00001)) in tissues from SCO compared to normal fertile men. Using ISH, miR-202-5p was localized to Sertoli cells of men with normal spermatogenesis, but not in the Sertoli cells of men with SCO. Conclusion: Number of miRNAs are differentially expressed in normal fertile men compared to men with SCO. MicroRNA-202-5p is localized to Sertoli cells and its expression dramatically differs between fertile men and men whose germ cells are depleted, suggesting a novel interaction for regulating microRNA expression between the somatic and germ cell components of the seminiferous epithelium.