Identification of the X-linked germ cell specific miRNAs (XmiRs) and their functions.
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ABSTRACT: MicroRNAs (miRNAs) play a critical role in multiple aspects of biology. Dicer, an RNase III endonuclease, is essential for the biogenesis of miRNAs, and the germ cell-specific Dicer1 knockout mouse shows severe defects in gametogenesis. How miRNAs regulate germ cell development is still not fully understood. In this study, we identified germ cell-specific miRNAs (miR-741-3p, miR-871-3p, miR-880-3p) by analyzing published RNA-seq data of mouse. These miRNA genes are contiguously located on the X chromosome near other miRNA genes. We named them X chromosome-linked miRNAs (XmiRs). To elucidate the functions of XmiRs, we generated knockout mice of these miRNA genes using the CRISPR/Cas9-mediated genome editing system. Although no histological abnormalities were observed in testes of F0 mice in which each miRNA gene was disrupted, a deletion covering miR-871 and miR-880 or covering all XmiRs (?XmiRs) resulted in arrested spermatogenesis in meiosis in a few seminiferous tubules, indicating their redundant functions in spermatogenesis. Among candidate targets of XmiRs, we found increased expression of a gene encoding a WNT receptor, FZD4, in ?XmiRs testis compared with that in wildtype testis. miR-871-3p and miR-880-3p repressed the expression of Fzd4 via the 3'-untranslated region of its mRNA. In addition, downstream genes of the WNT/?-catenin pathway were upregulated in ?XmiRs testis. We also found that miR-871, miR-880, and Fzd4 were expressed in spermatogonia, spermatocytes and spermatids, and overexpression of miR-871 and miR-880 in germ stem cells in culture repressed their increase in number and Fzd4 expression. Previous studies indicated that the WNT/?-catenin pathway enhances and represses proliferation and differentiation of spermatogonia, respectively, and our results consistently showed that stable ?-catenin enhanced GSC number. In addition, stable ?-catenin partially rescued reduced GSC number by overexpression of miR-871 and miR-880. The results together suggest that miR-871 and miR-880 cooperatively regulate the WNT/?-catenin pathway during testicular germ cell development.
SUBMITTER: Ota H
PROVIDER: S-EPMC6358104 | biostudies-literature | 2019
REPOSITORIES: biostudies-literature
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