Biology subjects

Attie-Bitach, T.

Publications and source records attributed to Attie-Bitach, T..

4 recordsLinked to original sources

bioRxiv2025

De novo heterozygous variants in EHMT2 genocopy Kleefstra syndrome via loss of G9a methyltransferase activity

EHMT1 and EHMT2 genes encode human euchromatin histone lysine methyltransferase 1 and 2 (EHMT1 alias GLP; EHMT2 alias G9a) that form heteromeric GLP/G9a complexes with essential roles in epigenetic regulation of gene expression. While EHMT1 haploinsufficiency has been established as the cause of Kleefstra syndrome 1, the pathogenesis of G9a dysfunction in human disease remains largely unknown. We identified seven de novo EHMT2 variants in patients with clinical presentation, episignatures, histone modifications and transcriptomic profiles similar to those of Kleefstra syndrome 1. In vitro studies revealed that these variants encode for structurally stable G9a proteins that are catalytically incompetent due to aberrant interactions either with histone H3 tail or with S-adenosylmethionine. Heterozygous mice carrying a patient-derived variant exhibited growth retardation, facial/skull dysmorphia and aberrant behavior. Here we report pathogenic EHMT2 variants that likely exert dominant-negative effect on GLP/G9a complexes and thus genocopy the EHMT1 haploinsufficiency via a distinct molecular mechanism, defining an autosomal dominant EHMT2-related Kleefstra syndrome.

genetics↗

bioRxiv2022

A cell fate decision map reveals abundant direct neurogenesis in the human developing neocortex

The human neocortex has undergone strong evolutionary expansion, largely due to an increased progenitor population, the basal radial glial (bRG) cells. These cells are responsible for the production of a diversity of cell types, but the successive cell fate decisions taken by individual progenitors remains unknown. Here, we developed a semi-automated live/fixed correlative imaging method to generate a map of bRG cell division modes in early fetal tissue and cerebral organoids. Through the analysis of over 1,000 dividing progenitors, we show that bRG cells undergo abundant symmetric amplifying divisions, followed by frequent direct neurogenic divisions, bypassing intermediate progenitors. These direct neurogenic divisions are more abundant in the upper part of the subventricular zone. We furthermore demonstrate asymmetric Notch activation in the self-renewing daughter cells, independently of basal fiber inheritance. Our results reveal a remarkable conservation of fate decisions in cerebral organoids, supporting their value as models of early human neurogenesis.

developmental biology↗

bioRxiv2021

TALPID3/KIAA0586 regulates multiple aspects of neuromuscular patterning during gastrointestinal development in animal models and human

TALPID3/KIAA0586 is an evolutionary conserved protein, which plays an essential role in protein trafficking. Its role during gastrointestinal (GI) and enteric nervous system (ENS) development has not been studied previously. Here, we analysed chicken, mouse and human embryonic GI tissues with TALPID3 mutations. The GI tract of TALPID3 chicken embryos was shortened and malformed. Histologically, the gut smooth muscle was mispatterned and enteric neural crest cells were scattered throughout the gut wall. Analysis of the Hedgehog pathway and gut extracellular matrix provided causative reasons for these defects. Interestingly, chicken intra-species grafting experiments and a conditional knockout mouse model showed that ENS formation did not require TALPID3, but was dependent on correct environmental cues. Surprisingly, the lack of TALPID3 in enteric neural crest cells (ENCC) affected smooth muscle and epithelial development in a non cell-autonomous manner. Analysis of human gut fetal tissues with a KIAA0586 mutation showed strikingly similar findings compared to the animal models demonstrating conservation of TALPID3 and its necessary role in human GI tract development and patterning

developmental biology↗

bioRxiv2018

Integrated Clinical and Omics Approach to Rare Diseases: Novel Genes and Oligogenic Inheritance in Holoprosencephaly

PurposeHoloprosencephaly (HPE) is a pathology of forebrain development characterized by high phenotypic and locus heterogeneity. Seventeen genes are known so far in HPE but the understanding of its genetic architecture remains to be refined. Here, we investigated the oligogenic nature of HPE resulting from accumulation of variants in different relevant genes.\n\nMethodsExome data from 29 patients diagnosed with HPE and 51 relatives from 26 unrelated families were analyzed. Standard variant classification approach was improved with a gene prioritization strategy based on clinical ontologies and gene co-expression networks. Clinical phenotyping and exploration of cross-species similarities were further performed on a family-by-family basis.\n\nResultsWe identified 232 rare deleterious variants in HPE patients representing 180 genes significantly associated with key pathways of forebrain development including Sonic Hedgehog (SHH) and Primary Cilia. Oligogenic events were observed in 10 families and involved novel HPE genes including recurrently mutated genes (FAT1, NDST1, COL2A1 and SCUBE2) and genes implicated in cilia function.\n\nConclusionsThis study reports novel HPE-relevant genes and reveals the existence of oligogenic cases resulting from several mutations in SHH-related genes. It also underlines that integrating clinical phenotyping in genetic studies will improve the identification of causal variants in rare disorders.

genetics↗