Vancamp, P. | Search bioRxiv

bioRxiv2025

Maternal protein restriction alters chromatin accessibility in neuroprogenitors of the fetal hypothalamus of rats.

Maternal protein restriction (PR) is a risk factor for altered fetal neurodevelopment and an increased susceptibility to neurometabolic disorders later in life. Although structural and transcriptomic changes in the developing hypothalamus have been reported in PR-exposed offspring, the underlying regulatory mechanisms remain unclear. We hypothesized that maternal PR alters chromatin accessibility in hypothalamic neuroprogenitor cells, thereby disrupting gene regulation critical for cell fate specification. We performed ATAC-seq on hypothalamic neuroprogenitors isolated at gestational day 17 from rat fetuses that were exposed to an isocaloric PR diet. We identified 312 differentially accessible chromatin regions, including reduced accessibility near genes encoding Major Histocompatibility Complex class I (MHC-I) proteins, amino acid transporters and proteins involved in neuronal differentiation and synaptic signaling. Motif enrichment analysis revealed reduced accessibility at FOS/JUN and DBP binding sites in PR samples, alongside enrichment of Kruppel-like transcription factor motifs in more accessible regions. RNA-seq on neurospheres generated from these progenitors identified 91 differentially expressed genes, enriched in pathways related to cell proliferation, protein-lipid metabolism, and apoptosis. Mapping these genes onto previously generated single-cell RNA-seq data associated several of them with specific neuroprogenitor subpopulations. With the exception of two genes (RT1-A2 and Nav2), the differential ATAC-seq peaks did not correspond to a statistically significant difference in neighboring gene expression levels. Our preliminary findings suggest that maternal PR alters the chromatin landscape of fetal hypothalamic progenitors, potentially disrupting key developmental trajectories, representing a mechanism of fetal programming of metabolic dysfunction.

developmental biology↗

bioRxiv2020

ZIKA virus effects on neuroprogenitors are exacerbated by the main pyriproxyfen metabolite via thyroid hormone signaling disruption

North-Eastern Brazil saw intensive application of the insecticide pyriproxyfen (PPF) during the microcephaly outbreak caused by Zika virus (ZIKV). ZIKV requires the neural RNA-binding protein Musashi-1 to replicate. TH represses MSI1. Being a suspected TH disruptor, we hypothesized that co-exposure to the main metabolite of PPF, 4-OH-PPF, would exacerbate ZIKV effects through increased MSI1 expression. This was tested using in vitro mouse neurospheres and an in vivo TH signaling reporter model, Xenopus laevis. TH signaling was decreased by 4-OH-PPF in both models. In mouse-derived neurospheres the metabolite reduced neuroprogenitor proliferation as well as markers of neuronal differentiation. The results demonstrated that 4-OH-PPF significantly induced MSI1 at both the mRNA and protein level, as well as Fasn mRNA. Other TH target genes were also significantly modified. Importantly, several key genes implicated in neuroprogenitor fate and commitment were not dysregulated by 4-OH-PPF alone, but were in combination with ZIKV infection. These included the neuroprogenitor markers Nestin, Egfr, Gfap, Dlx2 and Dcx. Unexpectedly, 4-OH-PPF decreased ZIKV replication, although only at the fourth and last day of incubation, and RNA copy numbers stayed within the same order of magnitude. However, intracellular RNA content of neuroprogenitors was significantly decreased in the combined presence of the PPF metabolite and ZIKV. We conclude that 4-OH-PPF interferes with TH action in vivo and in vitro, inhibiting neuroprogenitor proliferation. In the presence of ZIKV, TH signaling pathways crucial for cortical development are significantly impacted. This provides another example of viral effects that are exacerbated by drug or pesticide use. Significance statementIn 2015, an increase in children born with unusually small heads (microcephaly) in North-Eastern Brazil was linked to infection with the ZIKA virus. An insecticide with thyroid hormone disruptive properties was used in the same areas. We investigated whether simultaneous exposure to the insecticide could increase viral susceptibility. The main metabolite 4-OH-PPF dysregulated thyroid hormone signaling pathways crucial for brain development in both models used. Neural stem cells proliferated less and contained more Musashi-1, a protein the virus needs to replicate. Infecting stem cells pre-exposed to the endocrine disruptor did not amplify viral replication, but aggravated expression of genes implicated in brain development. Our results suggest the insecticide is particularly deleterious to brain development in areas with ZIKA virus prevalence.

neuroscience↗