Biology subjects

Dhellemmes, M.

Publications and source records attributed to Dhellemmes, M..

3 recordsLinked to original sources

bioRxiv2026

Rspo1 dependent WNT signaling safeguards ovarian development by suppressing androgen signaling

Embryonic ovarian development requires high levels of WNT/B-catenin signaling yet the molecular basis of this requirement remains unclear. Mutations in the WNT potentiator RSPO1 impair ovarian development in both mouse and human, leading to gonadal masculinization in XX individuals. Here, we show that RSPO1 acts within a restricted developmental window at the onset of ovarian differentiation and that its absence triggers precocious androgen signaling in the developing ovaries. Moreover, androgen receptor inhibition rescues ovarian development in Rspo1 mutant mice. Our findings identify RSPO1/WNT/B-catenin signaling as an essential pathway that suppresses androgen signaling to ensure proper ovarian development in mouse.

developmental biology↗

bioRxiv2024

NR2F2 is required in the embryonic testis for Fetal Leydig Cell development

Male genital development in XY mammalian fetuses is triggered by the action of hormones, including testosterone, secreted by the developing testes. Defects in this process are a cause for Differences in Sex Development (DSD), one of the most common congenital abnormalities in humans. Fetal Leydig Cells (FLC) play a central role for the synthesis of masculinizing hormones in the developing testes. Yet, the genetic cascade controlling their differentiation is poorly understood. Here we investigate the role of the orphan nuclear receptor NR2F2 (COUP-TFII) in FLC development. We report that NR2F2 is expressed in interstitial progenitor cells of the mouse embryonic testes and is downregulated upon their differentiation into FLC. By using two mouse models for conditional mutation of Nr2f2 in the developing testes, we demonstrate that NR2F2 is required for testis morphogenesis and FLC development. NR2F2 acts in interstitial progenitors to regulate the initiation and progression of FLC differentiation. These results establish NR2F2 as an essential regulator of FLC development and steroid hormone synthesis in the mouse fetal testis and provide an entry point to understand the etiology of 46, XY DSD associated with pathogenic NR2F2 variants.

developmental biology↗

bioRxiv2021

Oligogenic heterozygous inheritance of sperm abnormalities in mouse

Male infertility is an important health concern that is expected to have a major genetic etiology. Although high-throughput sequencing has linked gene defects to more than 50% of rare and severe sperm anomalies, less than 20% of common and moderate forms are explained. We hypothesized that this low success rate could at least be partly due to oligogenic defects - the accumulation of several rare heterozygous variants in distinct, but functionally connected, genes. Here, we compared fertility and sperm parameters in male mice harboring one to four heterozygous truncating mutations of genes linked to multiple morphological anomalies of the flagellum (MMAF) syndrome. Results indicated progressively deteriorating sperm morphology and motility with increasing numbers of heterozygous mutations. This first evidence of oligogenic inheritance in failed spermatogenesis strongly suggests that oligogenic heterozygosity could explain a significant proportion of asthenoteratozoospermia cases. The findings presented pave the way to further studies in mice and man.

genetics↗