Role of Dicer1-dependent microRNAs in the paracrine control of epididymal gene expression

Dicer1 is an endoribonuclease involved in the biogenesis of functional microRNAs (miRNAs). These small non-coding RNAs are important regulators of the posttranscriptional gene expression and participate to the control of male fertility. Knowing that 1) Dicer1-dependent factors are needed for proper sperm maturation in the epididymis, and that 2) miRNAs are potent mediators of intercellular communication in most biological systems, we investigated the role of Dicer1 dependent-miRNAs produced from the proximal epididymis (initial segment/caput) on the paracrine regulation of epididymal gene expression in the distal epididymis regions (i.e. corpus and cauda). To this aim, we performed comparative microarray and ANOVA analyses on control vs. Defb41iCre/wt;Dicer1fl/fl mice in which functional Dicer1 is absent from the principal cells of the proximal epididymis. We identified 21 and 16 transcripts, including Prostate And Testis Expressed 4 protein and the Zn-alpha 2-glycoprotein, that display significant expression level changes in the corpus and cauda regions, respectively (Fold change >2 or <-2; p<0.001). In addition, 154 miRNAs, including miR- 210, miR-672, miR-191 and miR-204, show a significantly impaired biogenesis in the absence of Dicer1 from the proximal epididymis (Fold change>2 or <-2; p<0.01). These miRNAs are secreted via extracellular vesicles derived from DC2 epididymal principal cell line, and their expression correlates with target transcripts involved in important biological pathways, as evidenced by in silico analysis. These observations suggest that Dicer1-dependent miRNAs could act as potent paracrine regulators of epididymal functions (i.e. control of sperm motility, ciliogenesis) and may contribute to the infertility phenotype observed in the Defb41iCre/wt;Dicer1fl/fl mouse model. These findings open new avenues for the identification of molecular targets important to male fertility control.

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