Identification of <i>miR‐34c‐5p</i> as a potential regulatory molecule associated with testicular development of black goat

The growth and maturation of Sertoli cells (SCs) are important part of testicular development and miRNAs are considered as novel regulatory molecules involved in it. Here we systematically screened and analyzed the key miRNAs participating in testicular development of black goat, as well as identified underlying mechanism of candidate mRNAs that contributed to spermatogenesis. The miRNA transcriptional profiles of testicular tissues at 3 days old (D3), 30 days old (D30), 90 days old (D90), and 180 days old (D180) were constructed and comparative analyzed. Results showed that the most differentially expressed (DE) miRNAs were found between the testicular tissues of D30 and D90 black goats. Moreover, the predicted target genes of DE miRNAs were mainly enriched in biological processes including cell proliferation, cell composition and enriched in signaling pathways including p53, FoxO, and PI3K-Akt. The top one DE miRNA (miR-34c-5p), which significantly highly expressed in the testis of D90 when compared to that of D30, was mainly located within SCs and targeted to IGF1R. By performing miR-34c-5p overexpression and RNA interference, we found that the function of miR-34c-5p in SCs was inhibited cell proliferation, increased apoptosis rate, and significantly reduced the expression of growth factors (CXCL12, BMP4, GDNF, and IGF1). In summary, our study suggests that miR-34c-5p can serve as a potential target for regulation of testicular development and a reference marker of puberty applied to black goat genetic breeding.