Biology subjects

Drouot, N.

Publications and source records attributed to Drouot, N..

3 recordsLinked to original sources

bioRxiv2026

FMRP controls diacylglycerol-dependent neuronal activity by mediating m6A-regulated translation efficiency

Fragile X syndrome (FXS), a leading inherited cause of intellectual developmental disorder and autism, results from loss of the RNA-binding protein FMRP. Loss of FMRP causes excessive neuronal protein synthesis contributing to widespread functional disturbances, yet the mechanisms linking FMRP to specific mRNA targets remain unclear. We show that FMRP promotes translation of the brain mRNA DGK{kappa} by binding mA-modified repetitive RNA motifs, thereby relieving a translational block encoded within its sequence. FMRP loss sharply reduces neuronal DGK{kappa}, and DGK{kappa} depletion alone reproduces hallmark FXS phenotypes, including hyperactivity, compulsive behavior, overgrowth, dendritic spine abnormalities, overactivated diacylglycerol signaling and increased protein synthesis. These findings identify DGK{kappa} as a key effector of FMRP function and establish a regulatory axis where mA RNA modification modulates neuronal translation. This work defines new principles of translational control in neurodevelopmental disorders and positions DGK{kappa} as a central driver of FXS pathogenesis.

molecular biology↗

bioRxiv2022

Molecular consequences of PQBP1 deficiency, involved in the X-linked Renpenning syndrome

Mutations in the PQBP1 gene (polyglutamine-binding protein 1) are responsible for a syndromic X-linked form of intellectual disability (XLID), the Renpenning syndrome. PQBP1 encodes a protein that plays a role in the regulation of gene expression, splicing and mRNA translation. To investigate the consequences of variants in PQBP1, we performed transcriptomic studies in 1) patients lymphoblastoid cell lines (LCL) carrying pathogenic variants in PQBP1 and 2) in human neural stem cells (hNSC) knocked-down (KD) for PQBP1. This led to the identification of a hundred dysregulated genes. In particular, we identified an increase in the expression of a non-canonical isoform of another XLID gene, UPF3B. UPF3B plays a crucial role during neurodevelopment by coding for an important actor of the nonsense mRNA mediated decay (NMD) system involved in regulation of protein translation, however, the exact function of the non-canonical isoform,UPF3B_S, is currently unknown. In order to investigate the role of UPF3B_S isoform, we compared the protein interactome of UPF3B_S to the canonical isoform (UPF3B_L). We confirmed that, on the contrary to UPF3B_L, UPF3B_S does not interact with the UPF2/UPF1 complex while it still interacts with exon junction complexes (EJC). However, no notable decrease of NMD pathways was observed in patients LCL or in hNSC KD for PQBP1. We identified several additional protein interactors specific to UPF3B_S. Moreover, we used the increase of UPF3B_S mRNA as a molecular marker to test the pathogenicity of variants of unknown clinical significance identified in individuals with ID in PQPB1. We analyzed patients LCL mRNA as well as blood mRNA samples and performed complementation studies in HeLa cells by overexpressing Wild-type and mutant PQBP1 cDNA. We showed that all these three approaches were efficient to test the effect of variants, at least for variants affecting the CTD domain of the protein. In conclusion, our study provides information on how PQBP1 deficiency may affect the expression of genes and isoforms, such as UPF3B. This informs about the pathological mechanisms involved in Renpenning syndrome but also allows to propose a functional test for variants of unknown significance identified in PQBP1.

genetics↗

bioRxiv2019

Highly clustered de novo frameshift variants in the neuronal splicing factor NOVA2 result in a specific abnormal C terminal part and cause a severe form of intellectual disability with autistic features.

The Neuro-Oncological Ventral Antigen 2 NOVA2 protein is a major factor regulating neuron specific alternative splicing, previously associated with an acquired neurologic condition, the paraneoplastic opsoclonus-myoclonus ataxia (POMA). We report here six individuals with de novo frameshift variants in the NOVA2 gene affected with a severe neurodevelopmental disorder characterized by intellectual disability (ID), motor and speech delay, autistic features, hypotonia, feeding difficulties, spasticity or ataxic gait and abnormal brain MRI. The six variants lead to the same reading frame, adding a common 133 aa long proline rich C-terminus part instead of the last KH RNA binding domain. We detected forty-one genes differentially spliced after NOVA2 inactivation in human neural cells. The mutant NOVA2 protein shows decreased ability to bind a target RNA, to regulate specific splicing events and to rescue the phenotype of altered retinotectal axonal pathfinding induced by loss of NOVA2 ortholog in zebrafish. Our results suggest a partial loss-of-function mechanism rather than a full heterozygous loss of function, although a specific contribution of the novel C terminal extension cannot be excluded on the basis of the genetic findings.

genetics↗