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Kreimer A, Ashuach T, Inoue F, Khodaverdian A, Deng C, Yosef N, Ahituv N. Massively parallel reporter perturbation assays uncover temporal regulatory architecture during neural differentiation. Nat Commun 2022; 13:1504. [PMID: 35315433 PMCID: PMC8938438 DOI: 10.1038/s41467-022-28659-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 02/04/2022] [Indexed: 02/08/2023] Open
Abstract
Gene regulatory elements play a key role in orchestrating gene expression during cellular differentiation, but what determines their function over time remains largely unknown. Here, we perform perturbation-based massively parallel reporter assays at seven early time points of neural differentiation to systematically characterize how regulatory elements and motifs within them guide cellular differentiation. By perturbing over 2,000 putative DNA binding motifs in active regulatory regions, we delineate four categories of functional elements, and observe that activity direction is mostly determined by the sequence itself, while the magnitude of effect depends on the cellular environment. We also find that fine-tuning transcription rates is often achieved by a combined activity of adjacent activating and repressing elements. Our work provides a blueprint for the sequence components needed to induce different transcriptional patterns in general and specifically during neural differentiation. How gene regulatory elements regulate gene expression during cellular differentiation remains largely unknown. Here the authors use perturbation-based massively parallel reporter assays at early time points of neural differentiation to systematically characterize how regulatory elements and motifs within them guide different transcriptional patterns.
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Neha S, Dholaniya PS. The Prevailing Role of Topoisomerase 2 Beta and its Associated Genes in Neurons. Mol Neurobiol 2021; 58:6443-6459. [PMID: 34546528 DOI: 10.1007/s12035-021-02561-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 09/11/2021] [Indexed: 12/01/2022]
Abstract
Topoisomerase 2 beta (TOP2β) is an enzyme that alters the topological states of DNA by making a transient double-strand break during the transcription process. The direct interaction of TOP2β with DNA strand results in transcriptional regulation of certain genes and some studies have suggested that a particular set of genes are regulated by TOP2β, which have a prominent role in various stages of neuron from development to degeneration. In this review, we discuss the role of TOP2β in various phases of the neuron's life. Based on the existing reports, we have compiled the list of genes, which are directly regulated by the enzyme, from different studies and performed their functional classification. We discuss the role of these genes in neurogenesis, neuron migration, fate determination, differentiation and maturation, generation of neural circuits, and senescence.
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Affiliation(s)
- Neha S
- Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad, Hyderabad, Telangana, 500 046, India
| | - Pankaj Singh Dholaniya
- Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad, Hyderabad, Telangana, 500 046, India.
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Reichard J, Zimmer-Bensch G. The Epigenome in Neurodevelopmental Disorders. Front Neurosci 2021; 15:776809. [PMID: 34803599 PMCID: PMC8595945 DOI: 10.3389/fnins.2021.776809] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 10/04/2021] [Indexed: 12/26/2022] Open
Abstract
Neurodevelopmental diseases (NDDs), such as autism spectrum disorders, epilepsy, and schizophrenia, are characterized by diverse facets of neurological and psychiatric symptoms, differing in etiology, onset and severity. Such symptoms include mental delay, cognitive and language impairments, or restrictions to adaptive and social behavior. Nevertheless, all have in common that critical milestones of brain development are disrupted, leading to functional deficits of the central nervous system and clinical manifestation in child- or adulthood. To approach how the different development-associated neuropathologies can occur and which risk factors or critical processes are involved in provoking higher susceptibility for such diseases, a detailed understanding of the mechanisms underlying proper brain formation is required. NDDs rely on deficits in neuronal identity, proportion or function, whereby a defective development of the cerebral cortex, the seat of higher cognitive functions, is implicated in numerous disorders. Such deficits can be provoked by genetic and environmental factors during corticogenesis. Thereby, epigenetic mechanisms can act as an interface between external stimuli and the genome, since they are known to be responsive to external stimuli also in cortical neurons. In line with that, DNA methylation, histone modifications/variants, ATP-dependent chromatin remodeling, as well as regulatory non-coding RNAs regulate diverse aspects of neuronal development, and alterations in epigenomic marks have been associated with NDDs of varying phenotypes. Here, we provide an overview of essential steps of mammalian corticogenesis, and discuss the role of epigenetic mechanisms assumed to contribute to pathophysiological aspects of NDDs, when being disrupted.
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Affiliation(s)
- Julia Reichard
- Functional Epigenetics in the Animal Model, Institute for Biology II, RWTH Aachen University, Aachen, Germany
- Research Training Group 2416 MultiSenses-MultiScales, Institute for Biology II, RWTH Aachen University, Aachen, Germany
| | - Geraldine Zimmer-Bensch
- Functional Epigenetics in the Animal Model, Institute for Biology II, RWTH Aachen University, Aachen, Germany
- Research Training Group 2416 MultiSenses-MultiScales, Institute for Biology II, RWTH Aachen University, Aachen, Germany
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Akkaya C, Atak D, Kamacioglu A, Akarlar BA, Guner G, Bayam E, Taskin AC, Ozlu N, Ince-Dunn G. Roles of developmentally regulated KIF2A alternative isoforms in cortical neuron migration and differentiation. Development 2021; 148:dev.192674. [PMID: 33531432 DOI: 10.1242/dev.192674] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 01/18/2021] [Indexed: 11/20/2022]
Abstract
KIF2A is a kinesin motor protein with essential roles in neural progenitor division and axonal pruning during brain development. However, how different KIF2A alternative isoforms function during development of the cerebral cortex is not known. Here, we focus on three Kif2a isoforms expressed in the developing cortex. We show that Kif2a is essential for dendritic arborization in mice and that the functions of all three isoforms are sufficient for this process. Interestingly, only two of the isoforms can sustain radial migration of cortical neurons; a third isoform, lacking a key N-terminal region, is ineffective. By proximity-based interactome mapping for individual isoforms, we identify previously known KIF2A interactors, proteins localized to the mitotic spindle poles and, unexpectedly, also translation factors, ribonucleoproteins and proteins that are targeted to organelles, prominently to the mitochondria. In addition, we show that a KIF2A mutation, which causes brain malformations in humans, has extensive changes to its proximity-based interactome, with depletion of mitochondrial proteins identified in the wild-type KIF2A interactome. Our data raises new insights about the importance of alternative splice variants during brain development.
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Affiliation(s)
- Cansu Akkaya
- Department of Molecular Biology and Genetics, Koç University, 34450 Istanbul, Turkey
| | - Dila Atak
- Department of Molecular Biology and Genetics, Koç University, 34450 Istanbul, Turkey
| | - Altug Kamacioglu
- Department of Molecular Biology and Genetics, Koç University, 34450 Istanbul, Turkey
| | - Busra Aytul Akarlar
- Department of Molecular Biology and Genetics, Koç University, 34450 Istanbul, Turkey
| | - Gokhan Guner
- Department of Molecular Biology and Genetics, Koç University, 34450 Istanbul, Turkey
| | - Efil Bayam
- Department of Molecular Biology and Genetics, Koç University, 34450 Istanbul, Turkey
| | - Ali Cihan Taskin
- Embryo Manipulation Laboratory, Animal Research Facility, Translational Medicine Research Center, Koç University, 34450 Istanbul, Turkey
| | - Nurhan Ozlu
- Department of Molecular Biology and Genetics, Koç University, 34450 Istanbul, Turkey
| | - Gulayse Ince-Dunn
- Department of Molecular Biology and Genetics, Koç University, 34450 Istanbul, Turkey .,Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland
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Oproescu AM, Han S, Schuurmans C. New Insights Into the Intricacies of Proneural Gene Regulation in the Embryonic and Adult Cerebral Cortex. Front Mol Neurosci 2021; 14:642016. [PMID: 33658912 PMCID: PMC7917194 DOI: 10.3389/fnmol.2021.642016] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 01/26/2021] [Indexed: 12/21/2022] Open
Abstract
Historically, the mammalian brain was thought to lack stem cells as no new neurons were found to be made in adulthood. That dogma changed ∼25 years ago with the identification of neural stem cells (NSCs) in the adult rodent forebrain. However, unlike rapidly self-renewing mature tissues (e.g., blood, intestinal crypts, skin), the majority of adult NSCs are quiescent, and those that become 'activated' are restricted to a few neurogenic zones that repopulate specific brain regions. Conversely, embryonic NSCs are actively proliferating and neurogenic. Investigations into the molecular control of the quiescence-to-proliferation-to-differentiation continuum in the embryonic and adult brain have identified proneural genes encoding basic-helix-loop-helix (bHLH) transcription factors (TFs) as critical regulators. These bHLH TFs initiate genetic programs that remove NSCs from quiescence and drive daughter neural progenitor cells (NPCs) to differentiate into specific neural cell subtypes, thereby contributing to the enormous cellular diversity of the adult brain. However, new insights have revealed that proneural gene activities are context-dependent and tightly regulated. Here we review how proneural bHLH TFs are regulated, with a focus on the murine cerebral cortex, drawing parallels where appropriate to other organisms and neural tissues. We discuss upstream regulatory events, post-translational modifications (phosphorylation, ubiquitinylation), protein-protein interactions, epigenetic and metabolic mechanisms that govern bHLH TF expression, stability, localization, and consequent transactivation of downstream target genes. These tight regulatory controls help to explain paradoxical findings of changes to bHLH activity in different cellular contexts.
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Affiliation(s)
- Ana-Maria Oproescu
- Sunnybrook Research Institute, Biological Sciences Platform, Toronto, ON, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
| | - Sisu Han
- Sunnybrook Research Institute, Biological Sciences Platform, Toronto, ON, Canada
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Carol Schuurmans
- Sunnybrook Research Institute, Biological Sciences Platform, Toronto, ON, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
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Tuvikene J, Esvald EE, Rähni A, Uustalu K, Zhuravskaya A, Avarlaid A, Makeyev EV, Timmusk T. Intronic enhancer region governs transcript-specific Bdnf expression in rodent neurons. eLife 2021; 10:65161. [PMID: 33560226 PMCID: PMC7891933 DOI: 10.7554/elife.65161] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 02/08/2021] [Indexed: 12/14/2022] Open
Abstract
Brain-derived neurotrophic factor (BDNF) controls the survival, growth, and function of neurons both during the development and in the adult nervous system. Bdnf is transcribed from several distinct promoters generating transcripts with alternative 5' exons. Bdnf transcripts initiated at the first cluster of exons have been associated with the regulation of body weight and various aspects of social behavior, but the mechanisms driving the expression of these transcripts have remained poorly understood. Here, we identify an evolutionarily conserved intronic enhancer region inside the Bdnf gene that regulates both basal and stimulus-dependent expression of the Bdnf transcripts starting from the first cluster of 5' exons in mouse and rat neurons. We further uncover a functional E-box element in the enhancer region, linking the expression of Bdnf and various pro-neural basic helix–loop–helix transcription factors. Collectively, our results shed new light on the cell-type- and stimulus-specific regulation of the important neurotrophic factor BDNF.
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Affiliation(s)
- Jürgen Tuvikene
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Tallinn, Estonia.,Protobios LLC, Tallinn, Estonia
| | - Eli-Eelika Esvald
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Tallinn, Estonia.,Protobios LLC, Tallinn, Estonia
| | - Annika Rähni
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Tallinn, Estonia
| | - Kaie Uustalu
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Tallinn, Estonia
| | - Anna Zhuravskaya
- Centre for Developmental Neurobiology, King's College London, London, United Kingdom
| | - Annela Avarlaid
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Tallinn, Estonia
| | - Eugene V Makeyev
- Centre for Developmental Neurobiology, King's College London, London, United Kingdom
| | - Tõnis Timmusk
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Tallinn, Estonia.,Protobios LLC, Tallinn, Estonia
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Safari MS, Obexer D, Baier-Bitterlich G, Zur Nedden S. PKN1 Is a Novel Regulator of Hippocampal GluA1 Levels. Front Synaptic Neurosci 2021; 13:640495. [PMID: 33613259 PMCID: PMC7892898 DOI: 10.3389/fnsyn.2021.640495] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 01/18/2021] [Indexed: 11/13/2022] Open
Abstract
Alterations in the processes that control α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) expression, assembly and trafficking are closely linked to psychiatric and neurodegenerative disorders. We have recently shown that the serine/threonine kinase Protein kinase N1 (PKN1) is a developmentally active regulator of cerebellar synaptic maturation by inhibiting AKT and the neurogenic transcription factor neurogenic differentiation factor-2 (NeuroD2). NeuroD2 is involved in glutamatergic synaptic maturation by regulating expression levels of various synaptic proteins. Here we aimed to study the effect of Pkn1 knockout on AKT phosphorylation and NeuroD2 levels in the hippocampus and the subsequent expression levels of the NeuroD2 targets and AMPAR subunits: glutamate receptor 1 (GluA1) and GluA2/3. We show that PKN1 is expressed throughout the hippocampus. Interestingly, not only postnatal but also adult hippocampal phospho-AKT and NeuroD2 levels were significantly elevated upon Pkn1 knockout. Postnatal and adult Pkn1 -/- hippocampi showed enhanced expression of the AMPAR subunit GluA1, particularly in area CA1. Surprisingly, GluA2/3 levels were not different between both genotypes. In addition to higher protein levels, we also found an enhanced GluA1 content in the membrane fraction of postnatal and adult Pkn1 -/- animals, while GluA2/3 levels remained unchanged. This points toward a very specific regulation of GluA1 expression and/or trafficking by the novel PKN1-AKT-NeuroD2 axis. Considering the important role of GluA1 in hippocampal development as well as the pathophysiology of several disorders, ranging from Alzheimer's, to depression and schizophrenia, our results validate PKN1 for future studies into neurological disorders related to altered AMPAR subunit expression in the hippocampus.
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Affiliation(s)
- Motahareh Solina Safari
- CCB-Biocenter, Institute of Neurobiochemistry, Medical University of Innsbruck, Innsbruck, Austria
| | - Dido Obexer
- CCB-Biocenter, Institute of Neurobiochemistry, Medical University of Innsbruck, Innsbruck, Austria
| | | | - Stephanie Zur Nedden
- CCB-Biocenter, Institute of Neurobiochemistry, Medical University of Innsbruck, Innsbruck, Austria
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Mis EK, Sega AG, Signer RH, Cartwright T, Ji W, Martinez-Agosto JA, Nelson SF, Palmer CGS, Lee H, Mitzelfelt T, Konstantino M, Jeffries L, Khokha MK, Marco E, Martin MG, Lakhani SA. Expansion of NEUROD2 phenotypes to include developmental delay without seizures. Am J Med Genet A 2021; 185:1076-1080. [PMID: 33438828 DOI: 10.1002/ajmg.a.62064] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 11/29/2020] [Accepted: 12/09/2020] [Indexed: 01/23/2023]
Abstract
De novo heterozygous variants in the brain-specific transcription factor Neuronal Differentiation Factor 2 (NEUROD2) have been recently associated with early-onset epileptic encephalopathy and developmental delay. Here, we report an adolescent with developmental delay without seizures who was found to have a novel de novo heterozygous NEUROD2 missense variant, p.(Leu163Pro). Functional testing using an in vivo assay of neuronal differentiation in Xenopus laevis tadpoles demonstrated that the patient variant of NEUROD2 displays minimal protein activity, strongly suggesting a loss of function effect. In contrast, a second rare NEUROD2 variant, p.(Ala235Thr), identified in an adolescent with developmental delay but lacking parental studies for inheritance, showed normal in vivo NEUROD2 activity. We thus provide clinical, genetic, and functional evidence that NEUROD2 variants can lead to developmental delay without accompanying early-onset seizures, and demonstrate how functional testing can complement genetic data when determining variant pathogenicity.
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Affiliation(s)
- Emily K Mis
- Pediatric Genomics Discovery Program, Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Annalisa G Sega
- Pediatric Genomics Discovery Program, Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Rebecca H Signer
- Department of Psychiatry & Biobehavioral Sciences, University of California Los Angeles, Los Angeles, California, USA
| | | | - Weizhen Ji
- Pediatric Genomics Discovery Program, Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Julian A Martinez-Agosto
- Deparment of Pediatrics, University of California Los Angeles, Los Angeles, California, USA.,Department of Human Genetics, University of California Los Angeles, Los Angeles, California, USA
| | - Stanley F Nelson
- Department of Psychiatry & Biobehavioral Sciences, University of California Los Angeles, Los Angeles, California, USA.,Deparment of Pediatrics, University of California Los Angeles, Los Angeles, California, USA.,Department of Human Genetics, University of California Los Angeles, Los Angeles, California, USA.,Department of Pathology and Laboratory Medicine, University of California Los Angeles, Los Angeles, California, USA
| | - Christina G S Palmer
- Department of Psychiatry & Biobehavioral Sciences, University of California Los Angeles, Los Angeles, California, USA.,Department of Human Genetics, University of California Los Angeles, Los Angeles, California, USA.,Institute for Society and Genetics, University of California Los Angeles, Los Angeles, California, USA
| | - Hane Lee
- Department of Human Genetics, University of California Los Angeles, Los Angeles, California, USA.,Department of Pathology and Laboratory Medicine, University of California Los Angeles, Los Angeles, California, USA
| | - Thomas Mitzelfelt
- Pediatric Genomics Discovery Program, Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Monica Konstantino
- Pediatric Genomics Discovery Program, Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut, USA
| | | | - Lauren Jeffries
- Pediatric Genomics Discovery Program, Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Mustafa K Khokha
- Pediatric Genomics Discovery Program, Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut, USA.,Department of Genetics, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Elysa Marco
- Cortica, San Rafael, California, USA.,Pediatric Brain Center, University of California San Francisco, San Francisco, California, USA
| | - Martin G Martin
- Deparment of Pediatrics, University of California Los Angeles, Los Angeles, California, USA
| | - Saquib A Lakhani
- Pediatric Genomics Discovery Program, Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut, USA
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Disruption of NEUROD2 causes a neurodevelopmental syndrome with autistic features via cell-autonomous defects in forebrain glutamatergic neurons. Mol Psychiatry 2021; 26:6125-6148. [PMID: 34188164 PMCID: PMC8760061 DOI: 10.1038/s41380-021-01179-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 05/17/2021] [Accepted: 05/26/2021] [Indexed: 02/06/2023]
Abstract
While the transcription factor NEUROD2 has recently been associated with epilepsy, its precise role during nervous system development remains unclear. Using a multi-scale approach, we set out to understand how Neurod2 deletion affects the development of the cerebral cortex in mice. In Neurod2 KO embryos, cortical projection neurons over-migrated, thereby altering the final size and position of layers. In juvenile and adults, spine density and turnover were dysregulated in apical but not basal compartments in layer 5 neurons. Patch-clamp recordings in layer 5 neurons of juvenile mice revealed increased intrinsic excitability. Bulk RNA sequencing showed dysregulated expression of many genes associated with neuronal excitability and synaptic function, whose human orthologs were strongly associated with autism spectrum disorders (ASD). At the behavior level, Neurod2 KO mice displayed social interaction deficits, stereotypies, hyperactivity, and occasionally spontaneous seizures. Mice heterozygous for Neurod2 had similar defects, indicating that Neurod2 is haploinsufficient. Finally, specific deletion of Neurod2 in forebrain excitatory neurons recapitulated cellular and behavioral phenotypes found in constitutive KO mice, revealing the region-specific contribution of dysfunctional Neurod2 in symptoms. Informed by these neurobehavioral features in mouse mutants, we identified eleven patients from eight families with a neurodevelopmental disorder including intellectual disability and ASD associated with NEUROD2 pathogenic mutations. Our findings demonstrate crucial roles for Neurod2 in neocortical development, whose alterations can cause neurodevelopmental disorders including intellectual disability and ASD.
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