Biology subjects

Bensaid, M.

Publications and source records attributed to Bensaid, M..

3 recordsLinked to original sources

bioRxiv2022

AUTS2 expression within mammalian lineage: a predictor of neural networks involved in Autism Spectrum Disorders

Autism susceptibility gene 2 (AUTS2) is a neurodevelopmental regulator associated with an autosomal dominant neurological syndrome with ASD-like (Autism Spectrum Disorder-like) features. The AUTS2 syndrome phenotype includes borderline to severe intellectual disability (ID), microcephaly and mild dysmorphic traits. Specific ASD-like features, including obsessive or ritualistic behaviours, are frequently displayed, although sociability is largely unaffected. Syndrome severity is worse when mutations are present in the 3 region (exons 9-19) of the AUTS2 gene. AUTS2 is also associated with alcohol consumption, heroin dependence, schizophrenia and dyslexia, using GWAS studies. Our working hypothesis is that AUTS2 expression during mammalian evolution can be instrumental to predict phenotypes linked to the disease. For that, we studied brain In Situ Hybridization (ISH) data in mouse, marmoset, human embryo and fetuses and sequences data of Neanderthal, Denisovan and modern humans. Developmental mouse brain expression is found in neocortex, hippocampus, thalamus, tegmentum and cerebellum suggesting a link linked with cognition, stereotypies and perseverative behaviors. Expression in amygdala and claustrum found in marmoset extend these phenotypes to anxiety and higher-order cognitive processes. In human embryos (8 weeks) and fetuses (15- and 19-weeks), we found AUTS2 expression in similar regions but also in medial, lateral and caudal ganglionic eminence, that are involved in the diversity of interneurons found in neocortex, hippocampus and striatum. Sequence comparison of AUTS2 locus in Neanderthal, Denisova and modern human reveals novel sites in regulatory regions of AUTS2. Altogether, these results suggest that ISH distribution along mammals is a novel phenotype-related biomarker useful for translational research.

neuroscience↗

bioRxiv2022

AUTS2 gene dosage affects synaptic AMPA receptors via a local dendritic spine AUTS2-TTC3-AKT-mTORC1 signaling dysfunction

The Human 1.2-Mb AUTS2 locus on chromosome 7q11.22 encodes a 1259-aa full-length protein, and a 711-aa C-terminal isoform. Functions of these AUTS2 proteins are only partly known. The major traits found in patients displaying AUTS2 locus mutations are Intellectual Disabilities, microcephaly attention deficit hyperactivity disorder (ADHD) (54%), and autistic traits. Furthermore, AUTS2 common variants were recently found associated to alcohol consumption and dyslexia using GWAS approaches. Auts2 localizes mainly in cell nuclei. We evidenced by super-resolution that Auts2 is present in dendritic spines. Auts2 interacts with Ttc3, the Akt2 E3 ligase, and negatively regulates Akt2 ubiquitination. Auts2 haploinsufficiency affects Akt/mTorc1 pathway with a decrease in AMPA and NMDA receptor subunits and in synaptic currents. Akt2 injection in postsynaptic neurons is sufficient to reverse changes in synaptic currents generated by Auts2 haploinsufficiency. Using chromosome engineering based on targeted meiotic recombination, we generated two mouse models with Auts2 locus deletion and duplication. Deleted Auts2 locus mice display stereotypies (rearing), perseveration and abnormal recognition memory. Duplicated Auts2 locus mice display similar perseveration and abnormal recognition memory but also a decrease in cued and contextual fear memory. Gene dosage induce changes in brain sub-region neuronal networks. In the thalamo-lateral amygdala pathway linked to cued fear memory, we found synaptic impairments linked to AMPA receptors, with a specific decrease in pAKT/total AKT ratio in duplicated Auts2 mice. Altogether, our study thereby provides a novel mechanistic and potentially therapeutic understanding of synaptic AKT/mTORC1 deregulated signaling and its related behavioral and cognitive phenotypes.

neuroscience↗

bioRxiv2019

Multi-hit autism genomic architecture evidenced from consanguineous families with involvement of FEZF2 and mutations in high-risk genes

Autism Spectrum Disorders (ASDs) are a heterogeneous collection of neurodevelopmental disorders with a strong genetic basis. Recent studies identified that a single hit of either a de novo or transmitted gene-disrupting, or likely gene-disrupting, mutation in a subset of 65 strongly associated genes can be sufficient to generate an ASD phenotype. We took advantage of consanguineous families with an ASD proband to evaluate this model. By a genome-wide homozygosity mapping of ten families with eleven children displaying ASD, we identified a linkage region of 133 kb in five families at the 3p14.2 locus that includes FEZF2 with a LOD score of 5.8 suggesting a founder effect. Sequencing FEZF2 revealed a common deletion of four codons. However, the damaging FEZF2 mutation did not appear to be sufficient to induce the disease as non-affected parents also carry the mutation and, similarly, Fezf2 knockout mouse embryos electroporated with the mutant human FEZF2 construct did not display any obvious defects in the corticospinal tract, a pathway whose development depends on FEZF2. We extended the genetic analysis of these five FEZF2-linked families versus five FEZF2 non-linked families by studying de novo and transmitted copy number variation (CNV) and performing Whole Exome Sequencing (WES). We identified damaging mutations in the subset of 65 genes strongly associated with ASD whose co-expression analysis suggests an impact on the prefrontal cortex during the mid-fetal periods. From these results, we propose that both FEZF2 deletion and multiple hits in the repertoire of these 65 genes are necessary to generate an ASD phenotype.\n\nSignificance StatementThe human neocortex is a highly organized laminar structure with neuron positioning and identity of deep-layer cortical neurons that depend on key transcription factors, such as FEZF2, SATB2, TSHZ3 and TBR1. These genes have a specific spatio-temporal pattern of expression in human midfetal deep cortical projection neurons and display mutations in patients with Autism Spectrum Disorder (ASD). Here, we identified a linkage region involving FEZF2 gene in five consanguineous families with an ASD proband. For these FEZF2-allele linked probands, we identified a four-codon deletion in FEZF2 and damaging mutations in other high-risk ASD genes, that exhibit regional and cell type-specific convergence in neocortical deep-layer excitatory neurons, suggesting a multi-hit genomic architecture of ASD in these consanguineous families.

neuroscience↗