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Germline Chd8 haploinsufficiency alters brain development in mouse. Nat Neurosci 2017; 20:1062-1073. [PMID: 28671691 DOI: 10.1038/nn.4592] [Citation(s) in RCA: 158] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 05/23/2017] [Indexed: 02/06/2023]
Abstract
The chromatin remodeling gene CHD8 represents a central node in neurodevelopmental gene networks implicated in autism. We examined the impact of germline heterozygous frameshift Chd8 mutation on neurodevelopment in mice. Chd8+/del5 mice displayed normal social interactions with no repetitive behaviors but exhibited cognitive impairment correlated with increased regional brain volume, validating that phenotypes of Chd8+/del5 mice overlap pathology reported in humans with CHD8 mutations. We applied network analysis to characterize neurodevelopmental gene expression, revealing widespread transcriptional changes in Chd8+/del5 mice across pathways disrupted in neurodevelopmental disorders, including neurogenesis, synaptic processes and neuroimmune signaling. We identified a co-expression module with peak expression in early brain development featuring dysregulation of RNA processing, chromatin remodeling and cell-cycle genes enriched for promoter binding by Chd8, and we validated increased neuronal proliferation and developmental splicing perturbation in Chd8+/del5 mice. This integrative analysis offers an initial picture of the consequences of Chd8 haploinsufficiency for brain development.
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Chen LF, Zhou AS, West AE. Transcribing the connectome: roles for transcription factors and chromatin regulators in activity-dependent synapse development. J Neurophysiol 2017; 118:755-770. [PMID: 28490640 DOI: 10.1152/jn.00067.2017] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 05/09/2017] [Accepted: 05/09/2017] [Indexed: 12/21/2022] Open
Abstract
The wiring of synaptic connections in the developing mammalian brain is shaped by both intrinsic and extrinsic signals. One point where these regulatory pathways converge is via the sensory experience-dependent regulation of new gene transcription. Recent studies have elucidated a number of molecular mechanisms that allow nuclear transcription factors and chromatin regulatory proteins to encode aspects of specificity in experience-dependent synapse development. Here we review the evidence for the transcriptional mechanisms that sculpt activity-dependent aspects of synaptic connectivity during postnatal development and discuss how disruption of these processes is associated with aberrant brain development in autism and intellectual disability.
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Affiliation(s)
- Liang-Fu Chen
- Department of Neurobiology, Duke University, Durham, North Carolina
| | - Allen S Zhou
- Department of Neurobiology, Duke University, Durham, North Carolina
| | - Anne E West
- Department of Neurobiology, Duke University, Durham, North Carolina
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Keown CL, Datko MC, Chen CP, Maximo JO, Jahedi A, Müller RA. Network organization is globally atypical in autism: A graph theory study of intrinsic functional connectivity. BIOLOGICAL PSYCHIATRY: COGNITIVE NEUROSCIENCE AND NEUROIMAGING 2017; 2:66-75. [PMID: 28944305 DOI: 10.1016/j.bpsc.2016.07.008] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
BACKGROUND Despite abundant evidence of brain network anomalies in autism spectrum disorder (ASD), findings have varied from broad functional underconnectivity to broad overconnectivity. Rather than pursuing overly simplifying general hypotheses ('under' vs. 'over'), we tested the hypothesis of atypical network distribution in ASD (i.e., participation of unusual loci in distributed functional networks). METHODS We used a selective high-quality data subset from the ABIDE datashare (including 111 ASD and 174 typically developing [TD] participants) and several graph theory metrics. Resting state functional MRI data were preprocessed and analyzed for detection of low-frequency intrinsic signal correlations. Groups were tightly matched for available demographics and head motion. RESULTS As hypothesized, the Rand Index (reflecting how similar network organization was to a normative set of networks) was significantly lower in ASD than TD participants. This was accounted for by globally reduced cohesion and density, but increased dispersion of networks. While differences in hub architecture did not survive correction, rich club connectivity (among the hubs) was increased in the ASD group. CONCLUSIONS Our findings support the model of reduced network integration (connectivity with networks) and differentiation (or segregation; based on connectivity outside network boundaries) in ASD. While the findings applied at the global level, they were not equally robust across all networks and in one case (greater cohesion within ventral attention network in ASD) even reversed.
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Affiliation(s)
- Christopher L Keown
- Brain Development Imaging Laboratory, Department of Psychology, San Diego State University, San Diego, CA, United States.,Department of Cognitive Science, University of California, San Diego, CA
| | - Michael C Datko
- Brain Development Imaging Laboratory, Department of Psychology, San Diego State University, San Diego, CA, United States.,Department of Cognitive Science, University of California, San Diego, CA
| | - Colleen P Chen
- Brain Development Imaging Laboratory, Department of Psychology, San Diego State University, San Diego, CA, United States.,Computational Science Research Center, San Diego State University, San Diego, CA
| | - José Omar Maximo
- Brain Development Imaging Laboratory, Department of Psychology, San Diego State University, San Diego, CA, United States
| | - Afrooz Jahedi
- Brain Development Imaging Laboratory, Department of Psychology, San Diego State University, San Diego, CA, United States.,Department of Mathematics and Statistics, San Diego State University, San Diego, CA, United States
| | - Ralph-Axel Müller
- Brain Development Imaging Laboratory, Department of Psychology, San Diego State University, San Diego, CA, United States
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Kwan V, Unda BK, Singh KK. Wnt signaling networks in autism spectrum disorder and intellectual disability. J Neurodev Disord 2016; 8:45. [PMID: 27980692 PMCID: PMC5137220 DOI: 10.1186/s11689-016-9176-3] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 11/07/2016] [Indexed: 12/20/2022] Open
Abstract
Background Genetic factors play a major role in the risk for neurodevelopmental disorders such as autism spectrum disorders (ASDs) and intellectual disability (ID). The underlying genetic factors have become better understood in recent years due to advancements in next generation sequencing. These studies have uncovered a vast number of genes that are impacted by different types of mutations (e.g., de novo, missense, truncation, copy number variations). Abstract Given the large volume of genetic data, analyzing each gene on its own is not a feasible approach and will take years to complete, let alone attempt to use the information to develop novel therapeutics. To make sense of independent genomic data, one approach is to determine whether multiple risk genes function in common signaling pathways that identify signaling “hubs” where risk genes converge. This approach has led to multiple pathways being implicated, such as synaptic signaling, chromatin remodeling, alternative splicing, and protein translation, among many others. In this review, we analyze recent and historical evidence indicating that multiple risk genes, including genes denoted as high-confidence and likely causal, are part of the Wingless (Wnt signaling) pathway. In the brain, Wnt signaling is an evolutionarily conserved pathway that plays an instrumental role in developing neural circuits and adult brain function. Conclusions We will also review evidence that pharmacological therapies and genetic mouse models further identify abnormal Wnt signaling, particularly at the synapse, as being disrupted in ASDs and contributing to disease pathology.
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Affiliation(s)
- Vickie Kwan
- Department of Biochemistry and Biomedical Sciences, Stem Cell and Cancer Research Institute, McMaster University, Hamilton, Ontario L8S 4K1 Canada
| | - Brianna K Unda
- Department of Biochemistry and Biomedical Sciences, Stem Cell and Cancer Research Institute, McMaster University, Hamilton, Ontario L8S 4K1 Canada
| | - Karun K Singh
- Department of Biochemistry and Biomedical Sciences, Stem Cell and Cancer Research Institute, McMaster University, Hamilton, Ontario L8S 4K1 Canada
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Lin YC, Frei JA, Kilander MBC, Shen W, Blatt GJ. A Subset of Autism-Associated Genes Regulate the Structural Stability of Neurons. Front Cell Neurosci 2016; 10:263. [PMID: 27909399 PMCID: PMC5112273 DOI: 10.3389/fncel.2016.00263] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 10/28/2016] [Indexed: 12/15/2022] Open
Abstract
Autism spectrum disorder (ASD) comprises a range of neurological conditions that affect individuals’ ability to communicate and interact with others. People with ASD often exhibit marked qualitative difficulties in social interaction, communication, and behavior. Alterations in neurite arborization and dendritic spine morphology, including size, shape, and number, are hallmarks of almost all neurological conditions, including ASD. As experimental evidence emerges in recent years, it becomes clear that although there is broad heterogeneity of identified autism risk genes, many of them converge into similar cellular pathways, including those regulating neurite outgrowth, synapse formation and spine stability, and synaptic plasticity. These mechanisms together regulate the structural stability of neurons and are vulnerable targets in ASD. In this review, we discuss the current understanding of those autism risk genes that affect the structural connectivity of neurons. We sub-categorize them into (1) cytoskeletal regulators, e.g., motors and small RhoGTPase regulators; (2) adhesion molecules, e.g., cadherins, NCAM, and neurexin superfamily; (3) cell surface receptors, e.g., glutamatergic receptors and receptor tyrosine kinases; (4) signaling molecules, e.g., protein kinases and phosphatases; and (5) synaptic proteins, e.g., vesicle and scaffolding proteins. Although the roles of some of these genes in maintaining neuronal structural stability are well studied, how mutations contribute to the autism phenotype is still largely unknown. Investigating whether and how the neuronal structure and function are affected when these genes are mutated will provide insights toward developing effective interventions aimed at improving the lives of people with autism and their families.
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Affiliation(s)
- Yu-Chih Lin
- Laboratory of Neuronal Connectivity, Program in Neuroscience, Hussman Institute for Autism, Baltimore MD, USA
| | - Jeannine A Frei
- Laboratory of Neuronal Connectivity, Program in Neuroscience, Hussman Institute for Autism, Baltimore MD, USA
| | - Michaela B C Kilander
- Laboratory of Neuronal Connectivity, Program in Neuroscience, Hussman Institute for Autism, Baltimore MD, USA
| | - Wenjuan Shen
- Laboratory of Neuronal Connectivity, Program in Neuroscience, Hussman Institute for Autism, Baltimore MD, USA
| | - Gene J Blatt
- Laboratory of Autism Neurocircuitry, Program in Neuroscience, Hussman Institute for Autism, Baltimore MD, USA
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Lai MC, Lerch JP, Floris DL, Ruigrok AN, Pohl A, Lombardo MV, Baron-Cohen S. Imaging sex/gender and autism in the brain: Etiological implications. J Neurosci Res 2016; 95:380-397. [DOI: 10.1002/jnr.23948] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Revised: 09/04/2016] [Accepted: 09/06/2016] [Indexed: 12/22/2022]
Affiliation(s)
- Meng-Chuan Lai
- Child and Youth Mental Health Collaborative at the Centre for Addiction and Mental Health and the Hospital for Sick Children, Department of Psychiatry; University of Toronto; Toronto Ontario Canada
- Autism Research Centre, Department of Psychiatry; University of Cambridge; Cambridge United Kingdom
- Department of Psychiatry; National Taiwan University Hospital and College of Medicine; Taipei Taiwan
| | - Jason P. Lerch
- Mouse Imaging Centre, Hospital for Sick Children; Toronto Ontario Canada
- Department of Medical Biophysics; University of Toronto; Toronto Ontario Canada
| | - Dorothea L. Floris
- Autism Research Centre, Department of Psychiatry; University of Cambridge; Cambridge United Kingdom
- New York University Child Study Center; New York New York USA
| | - Amber N.V. Ruigrok
- Autism Research Centre, Department of Psychiatry; University of Cambridge; Cambridge United Kingdom
| | - Alexa Pohl
- Autism Research Centre, Department of Psychiatry; University of Cambridge; Cambridge United Kingdom
| | - Michael V. Lombardo
- Autism Research Centre, Department of Psychiatry; University of Cambridge; Cambridge United Kingdom
- Department of Psychology and Center of Applied Neuroscience; University of Cyprus; Nicosia Cyprus
| | - Simon Baron-Cohen
- Autism Research Centre, Department of Psychiatry; University of Cambridge; Cambridge United Kingdom
- CLASS Clinic, Cambridgeshire and Peterborough NHS Foundation Trust; Cambridge United Kingdom
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Okerlund ND, Stanley RE, Cheyette BNR. The Planar Cell Polarity Transmembrane Protein Vangl2 Promotes Dendrite, Spine and Glutamatergic Synapse Formation in the Mammalian Forebrain. MOLECULAR NEUROPSYCHIATRY 2016; 2:107-14. [PMID: 27606324 DOI: 10.1159/000446778] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 05/11/2016] [Indexed: 12/27/2022]
Abstract
The transmembrane protein Vangl2, a key regulator of the Wnt/planar cell polarity (PCP) pathway, is involved in dendrite arbor elaboration, dendritic spine formation and glutamatergic synapse formation in mammalian central nervous system neurons. Cultured forebrain neurons from Vangl2 knockout mice have simpler dendrite arbors, fewer total spines, less mature spines and fewer glutamatergic synapse inputs on their dendrites than control neurons. Neurons from mice heterozygous for a semidominant Vangl2 mutation have similar but not identical phenotypes, and these phenotypes are also observed in Golgi-stained brain tissue from adult mutant mice. Given increasing evidence linking psychiatric pathophysiology to these subneuronal sites and structures, our findings underscore the relevance of core PCP proteins including Vangl2 to the underlying biology of major mental illnesses and their treatment.
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Affiliation(s)
- Nathan D Okerlund
- Department of Neurology and Neurological Sciences, Stanford University, Palo Alto, Calif., USA; Department of Psychiatry, Stanford University, Palo Alto, Calif., USA
| | - Robert E Stanley
- Department of Psychiatry, Stanford University, Palo Alto, Calif., USA; Tetrad Graduate Program, Stanford University, Palo Alto, Calif., USA
| | - Benjamin N R Cheyette
- Department of Psychiatry, Stanford University, Palo Alto, Calif., USA; Tetrad Graduate Program, Stanford University, Palo Alto, Calif., USA; UCSF Weill Institute for Neurosciences, University of California, San Francisco (UCSF), San Francisco, Calif., USA; Kavli Institute for Fundamental Neuroscience, University of California, San Francisco (UCSF), San Francisco, Calif., USA
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