The potential role of microRNAs in regulating gonadal sex differentiation in the chicken embryo

Abstract

Differential gene expression regulates tissue morphogenesis. The embryonic gonad is a good example, where the developmental decision to become an ovary or testis is governed by female-or male-specific gene expression. A number of genes have now been identified that control gonadal sex differentiation. However, the potential role of microRNAs (miRNAs) in ovarian and testicular pathways is unknown. In this review, we summarise our current understanding of gonadal differentiation and the possible involvement of miRNAs, using the chicken embryo as a model system. Chickens and other birds have a ZZ/ZW sex chromosome system, in which the female, ZW, is the heterogametic sex, and the male, ZZ, is homogametic (opposite to mammals). The Z-linked DMRT1 gene is thought to direct testis differentiation during embryonic life via a dosage-based mechanism. The conserved SOX9 gene is also likely to play a key role in testis formation. No master ovary determinant has yet been defined, but the autosomal FOXL2 and Aromatase genes are considered central. No miRNAs have been definitively shown to play a role in embryonic gonadal development in chickens or any other vertebrate species. Using next generation sequencing, we carried out an expression-based screen for miRNAs expressed in embryonic chicken gonads at the time of sexual differentiation. A number of miRNAs were identified, including several that showed sexually dimorphic expression. We validated a subset of miRNAs by qRT-PCR, and prediction algorithms were used to identify potential targets.Chromosome Res

Genome-Wide Identification of CBX2 Targets: Insights in the Human Sex Development Network

“…We also identified CBX2 binding near a considerable number of genes encoding microRNAs, implying a possible still undiscovered role of microRNAs in human sex development, similarly to what has been shown for microRNAs and testicular proteome in mice (28), as well as in gonadal sex differentiation in chicken embryos (29). Further characterization of the impact of CBX2 activation on microRNAs and their potential involvement in sexual development in humans is essential.…”

Characterization and differential expression of microRNAs in the ovaries of pregnant and non-pregnant goats (Capra hircus)

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