Biology subjects

Bellefroid, E.

Publications and source records attributed to Bellefroid, E..

3 recordsLinked to original sources

bioRxiv2025

AAV-mediated overexpression of Prdm12 in knee-innervating afferents reduces inflammatory joint pain and neuronal hyperexcitability in mice

Inflammatory joint pain features in numerous musculoskeletal disorders that affect millions globally. The Prdm12 gene encodes a conserved zinc finger transcriptional regulator expressed selectively in the nervous system. In humans, PRDM12 mutations can cause congenital insensitivity to pain (CIP) or midface toddler excoriation syndrome (MiTES). Prdm12 is prominently expressed in developing somatosensory ganglia, where it plays a crucial role in nociceptive neuron development, its expression being maintained in mature C-LTMRs (C-low threshold mechanoreceptors) and nociceptive neurons. Despite enhanced understanding of Prdm12s role in neuronal excitability and pain behavior, the impact of Prdm12 overexpression in mature nociceptive neurons has not been explored. Here, we conducted intravenous injection of AAV-PHP.S viral vectors encoding Prdm12-GFP (Prdm12-AAV) or GFP alone (Control-AAV), observing no overt changes in mouse behavior. When examining the properties of Prdm12 overexpressing sensory neurons in vitro, we observed an increase in rheobase alongside decreased neuronal responses to capsaicin and ATP, indicating a downregulation of TRPV1 and P2X ion channels activity, respectively. We next conducted intraarticular administration of viral constructs in female mice to determine how Prdm12 overexpression in knee-innervating sensory neurons alters their excitability and influences inflammatory joint pain induced by intraarticular administration of complete Freunds adjuvant (CFA). Prdm12 overexpression in knee-innervating neurons decreased inflammation-induced changes in digging and weight bearing, prevented inflammation-induced neuronal hyperexcitability, and decreased macroscopic voltage-gated ion channel conductance. Our findings illustrate that Prdm12 overexpression strongly modulates neuronal excitability in adult animals, highlighting its importance in pain perception and its potential as an analgesic target. SummaryOverexpression of the transcriptional regulator Prdm12 in knee-innervating neurons of mice reduces inflammatory joint pain and counteracts inflammation-induced neuronal hyperexcitability.

neuroscience↗

bioRxiv2024

Novel insights into Emx2 and Dmrta2 cooperation during cortex development and evidence for Dmrta2 function in choroid plexus

Early dorsal telencephalon development is coordinated by an interplay of transcription factors that exhibit a graded expression pattern in neural progenitors. How they function together to orchestrate cortical development remains largely unknown. The Emx2 and Dmrta2 genes encode TFs that are expressed in a similar caudomedialhigh/ rostrolaterallowgradient in the ventricular zone of the developing dorsal telencephalon with, in the medial pallium, Dmrta2 but not Emx2 expressed in the developing choroid plexus. Their constitutive loss has been shown to impart similar cortical abnormalities, and their combined deletion exacerbates the phenotypes, suggesting possible cooperation during cortex development. In this study, we utilized molecular and genetic approaches to dissect how Emx2 functions with Dmrta2 during cortical development. Our results show that while they regulate a similar set of genes, their common direct targets are limited but include key regulators of cortical development. Identification of the interaction partners of Emx2 suggests that it coordinates with the LIM-domain binding protein Ldb1 to execute the activation and repression of some of its downstream targets. Finally, while Emx2 is known to suppress choroid plexus development, we also provide evidence that Dmrta2 is in contrast required for choroid plexus since in its absence in medial telencephalic progenitors, mice develop hydrocephalous postnatally, a phenotype that appears to be due to a compromised cytoarchitecture. Together, these data indicate that Emx2 and Dmrta2 have similar but also distinct functions in telencephalon development and provide the first insights into Emx2 mechanism of action. SIGNIFICANCE STATEMENTEmx2 and Dmrta2 encode transcription factors that generate similar phenotypes upon their loss in the developing cortex suggesting possible cooperation. Here we explored how Emx2 functions with Dmrta2 during cortical development. Results obtained indicate that Emx2 directly regulates with Dmrta2 only a few genes, some coding for key cortical determinants and that Emx2 utilizes the Ldb1 cofactor for the regulation of some of its targets. Results also suggest that, unlike Emx2 which suppresses choroid plexus development, Dmrta2 is required for choroid plexus as its loss in medial telencephalic progenitors leads to hydrocephalus. Together, our results reveal that Emx2 and Dmrta2 have similar but also distinct functions during telencephalon development and provide novel insights into the mechanism of action of Emx2.

neuroscience↗

bioRxiv2021

Systematic mapping of rRNA 2'-O methylation during frog development and involvement of the methyltransferase Fibrillarin in eye and craniofacial development in Xenopus laevis

Ribosomes are essential nanomachines responsible for protein production. Although ribosomes are present in every living cell, ribosome biogenesis dysfunction diseases, called ribosomopathies, impact particular tissues specifically. Here, we evaluate the importance of the box C/D snoRNA-associated ribosomal RNA methyltransferase fibrillarin (Fbl) in the early embryonic development of Xenopus laevis. We report that in developing embryos, the neural plate, neural crest cells (NCCs), and NCC derivatives are rich in fbl transcripts. Fbl knockdown leads to striking morphological defects affecting the eyes and craniofacial skeleton, due to lack of NCC survival caused by massive p53-dependent apoptosis. Fbl is required for efficient pre-rRNA processing and 18S rRNA production, which explains the early developmental defects. Using RiboMethSeq, we systematically reinvestigated ribosomal RNA 2-O methylation in X. laevis, confirming all 89 previously mapped sites and identifying 15 novel putative positions in 18S and 28S rRNA. Twenty-three positions, including 10 of the new ones, were validated orthogonally by low dNTP primer extension. Bioinformatic screening of the X. laevis transcriptome revealed candidate box C/D snoRNAs for all methylated positions. Mapping of 2-O methylation at six developmental stages in individual embryos indicated a trend towards reduced methylation at specific positions during development. We conclude that fibrillarin knockdown in early Xenopus embryos causes reduced production of functional ribosomal subunits, thus impairing NCC formation and migration. AUTHOR SUMMARYRibosomes are essential nanomachines responsible for protein production in all cells. Ribosomopathies are diseases caused by improper ribosome formation due to mutations in ribosomal proteins or ribosome assembly factors. Such diseases primarily affect the brain and blood, and it is unclear how malfunctioning of a process as general as ribosome formation can lead to tissue-specific diseases. Here we have examined how fibrillarin, an enzyme which modifies ribosomal RNA by adding methyl groups at specific sites, affects early embryonic development in the frog Xenopus laevis. We have revealed its importance in the maturation of cells forming an embryonic structure called the neural crest. Fibrillarin depletion leads to reduced eye size and abnormal head shape, reminiscent of other conditions such as Treacher Collins syndrome. Molecularly, the observed phenotypes are explainable by increased p53-dependent programmed cell death triggered by inhibition of certain pre-rRNA processing steps. Our systematic investigation of the ribosomal RNA 2-O methylation repertoire across development has further revealed hypomodification at a late stage of development, which might play a role in late developmental transitions involving differential translation by compositionally different ribosomes.

developmental biology↗