Biology subjects

Jedamzick, J.

Publications and source records attributed to Jedamzick, J..

3 recordsLinked to original sources

bioRxiv2023

Complete male-to-female sex reversal in XY mice lacking the miR-17~92 cluster

In mammals, sex determination is controlled by antagonistic gene cascades operating in embryonic undifferentiated gonads1 2. The expression of the Y-linked gene SRY is sufficient to trigger the testicular pathway, whereas its absence in XX embryos leads to ovarian differentiation3 4 5. Despite this strong genetic component, the involvement of non-coding regulation in determining mammalian sex remains unclear6. 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. Time-course analyses revealed that Sry is heterochronically expressed, showing a delay in XY miR-17[~]92 knockout gonads, which subsequently activate the ovarian genetic program. Bulk and single cell RNA-seq analyses showed that Sertoli cell differentiation is reduced, delayed and unable to sustain the testicular fate. This disrupted differentiation results from a transient state of sex ambiguity in pre-supporting cells, which is later resolved towards the ovarian fate. Consistent with known mechanisms of miRNA-mediated gene regulation, the expression of miR-17[~]92 target genes is not stabilized in undifferentiated XY mutant gonads, affecting concomitantly the fine regulation of gene networks with critical roles in developing gonads. Our results demonstrate that microRNAs are key components for mammalian sex determination, controlling the timing of Sry expression and Sertoli cell differentiation.

developmental biology↗

bioRxiv2022

Sex-determining 3D regulatory hubs revealed by genome spatial auto-correlation analysis

Mammalian sex is determined by opposing networks of ovarian and testicular genes that are well characterized. However, its epigenetic regulation is still largely unknown, thus limiting our understanding of a fundamental process for species propagation. Here we explore the 3D chromatin landscape of sex determination in vivo, by profiling FACS-sorted embryonic mouse gonadal populations, prior and after sex determination, in both sexes. We integrate Hi-C with ChIP-seq experiments using METALoci, a novel genome spatial auto-correlation analysis that identifies 3D enhancer hubs across the genome. We uncover a prominent rewiring of chromatin interactions during sex determination, affecting the enhancer hubs of hundreds of genes that display temporal- and sex-specific expression. Moreover, the identification of the 3D enhancer hubs allows the reconstruction of regulatory networks, revealing key transcription factors involved in sex determination. By combining predictive approaches and validations in transgenic mice we identify a novel Fgf9 regulatory hub, deletion of which results in male-to-female sex reversal with the upregulation of ovarian-specific markers and the initiation of meiosis. Thus, spatial auto-correlation analysis is an effective strategy to identify regulatory networks associated to biological processes and to further characterize the functional role of the 3D genome.

developmental biology↗

bioRxiv2021

In vivo dissection of a clustered-CTCF domain boundary reveals developmental principles of regulatory insulation

Vertebrate genomes organize into topologically associating domains (TADs), delimited by boundaries that insulate regulatory elements from non-target genes. However, how boundary function is established is not well understood. Here, we combine genome-wide analyses and transgenic mouse assays to dissect the regulatory logic of clustered-CTCF boundaries in vivo, interrogating their function at multiple levels: chromatin interactions, transcription and phenotypes. Individual CTCF binding sites (CBS) deletions revealed that the characteristics of specific sites can outweigh other factors like CBS number and orientation. Combined deletions demonstrated that CBS cooperate redundantly and provide boundary robustness. We show that divergent CBS signatures are not strictly required for effective insulation and that chromatin loops formed by non-convergently oriented sites could be mediated by a loop interference mechanism. Further, we observe that insulation strength constitutes a quantitative modulator of gene expression and phenotypes. Our results highlight the modular nature of boundaries and their control over developmental processes.

developmental biology↗