ABSTRACT
Mammalian sex determination is controlled by antagonistic gene cascades operating in embryonic undifferentiated gonads. The expression of the Y-linked gene SRY is sufficient to trigger the testicular pathway, whereas its absence in XX embryos leads to ovarian differentiation. Yet, the potential involvement of non-coding regulation in this process remains unclear. Here we show that the deletion of a single microRNA cluster, miR-17~92, induces complete primary male-to-female sex reversal in XY mice. Sry expression is delayed in XY knockout gonads, which develop as ovaries. Sertoli cell differentiation is reduced, delayed and unable to sustain testicular development. Pre-supporting cells in mutant gonads undergo a transient state of sex ambiguity which is subsequently resolved towards the ovarian fate. The miR-17~92 predicted target genes are upregulated, affecting the fine regulation of gene networks controlling gonad development. Thus, microRNAs emerge as key components for mammalian sex determination, controlling Sry expression timing and Sertoli cell differentiation.
Subject(s)
Cell Differentiation , MicroRNAs , Ovary , Sertoli Cells , Sex Determination Processes , Sex-Determining Region Y Protein , Testis , Animals , MicroRNAs/genetics , MicroRNAs/metabolism , Female , Male , Sertoli Cells/metabolism , Sertoli Cells/cytology , Mice , Ovary/metabolism , Testis/metabolism , Sex-Determining Region Y Protein/genetics , Sex-Determining Region Y Protein/metabolism , Cell Differentiation/genetics , Sex Determination Processes/genetics , Gene Expression Regulation, Developmental , Mice, Knockout , Sex Differentiation/genetics , Disorders of Sex Development/genetics , Gonads/metabolismABSTRACT
Three-dimensional (3D)-chromatin organization is critical for proper enhancer-promoter communication and, therefore, for a precise execution of the transcriptional programs governing cellular processes. The emergence of Chromosome Conformation Capture (3C) methods, in particular Hi-C, has allowed the investigation of chromatin interactions on a genome-wide scale, revealing the existence of overlapping molecular mechanisms that we are just starting to decipher. Therefore, disentangling Hi-C signal into these individual components is essential to provide meaningful biological data interpretation. Here, we discuss emerging views on the molecular forces shaping the genome in 3D, with a focus on their respective contributions and interdependence. We discuss Hi-C data at both population and single-cell levels, thus providing criteria to interpret genomic function in the 3D-nuclear space.
