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Hurley S, Mohan C, Suetterlin P, Ellingford R, Riegman KLH, Ellegood J, Caruso A, Michetti C, Brock O, Evans R, Rudari F, Delogu A, Scattoni ML, Lerch JP, Fernandes C, Basson MA. Distinct, dosage-sensitive requirements for the autism-associated factor CHD8 during cortical development. Mol Autism 2021; 12:16. [PMID: 33627187 PMCID: PMC7905672 DOI: 10.1186/s13229-020-00409-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Accepted: 12/21/2020] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND CHD8 haploinsufficiency causes autism and macrocephaly with high penetrance in the human population. Chd8 heterozygous mice exhibit relatively subtle brain overgrowth and little gene expression changes in the embryonic neocortex. The purpose of this study was to generate new, sub-haploinsufficient Chd8 mouse models to allow us to identify and study the functions of CHD8 during embryonic cortical development. METHODS To examine the possibility that certain phenotypes may only appear at sub-heterozygous Chd8 levels in the mouse, we created an allelic series of Chd8-deficient mice to reduce CHD8 protein levels to approximately 35% (mild hypomorph), 10% (severe hypomorph) and 0% (neural-specific conditional knockout) of wildtype levels. We used RNA sequencing to compare transcriptional dysregulation, structural MRI and brain weight to investigate effects on brain size, and cell proliferation, differentiation and apoptosis markers in immunostaining assays to quantify changes in neural progenitor fate. RESULTS Mild Chd8 hypomorphs displayed significant postnatal lethality, with surviving animals exhibiting more pronounced brain hyperplasia than heterozygotes. Over 2000 genes were dysregulated in mild hypomorphs, including autism-associated neurodevelopmental and cell cycle genes. We identify increased proliferation of non-ventricular zone TBR2+ intermediate progenitors as one potential cause of brain hyperplasia in these mutants. Severe Chd8 hypomorphs displayed even greater transcriptional dysregulation, including evidence for p53 pathway upregulation. In contrast to mild hypomorphs, these mice displayed reduced brain size and increased apoptosis in the embryonic neocortex. Homozygous, conditional deletion of Chd8 in early neuronal progenitors resulted in pronounced brain hypoplasia, partly caused by p53 target gene derepression and apoptosis in the embryonic neocortex. Limitations Our findings identify an important role for the autism-associated factor CHD8 in controlling the proliferation of intermediate progenitors in the mouse neocortex. We propose that CHD8 has a similar function in human brain development, but studies on human cells are required to confirm this. Because many of our mouse mutants with reduced CHD8 function die shortly after birth, it is not possible to fully determine to what extent reduced CHD8 function results in autism-associated behaviours in mice. CONCLUSIONS Together, these findings identify important, dosage-sensitive functions for CHD8 in p53 pathway repression, neurodevelopmental gene expression and neural progenitor fate in the embryonic neocortex. We conclude that brain development is acutely sensitive to reduced CHD8 expression and that the varying sensitivities of different progenitor populations and cellular processes to CHD8 dosage result in non-linear effects on gene transcription and brain growth. Shaun Hurley, Conor Mohan and Philipp Suetterlin have contributed equally to this work.
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Affiliation(s)
- Shaun Hurley
- Centre for Craniofacial and Regenerative Biology, King's College London, London, UK
| | - Conor Mohan
- Centre for Craniofacial and Regenerative Biology, King's College London, London, UK
| | - Philipp Suetterlin
- Centre for Craniofacial and Regenerative Biology, King's College London, London, UK
| | - Robert Ellingford
- Centre for Craniofacial and Regenerative Biology, King's College London, London, UK
| | | | - Jacob Ellegood
- Department of Medical Biophysics, Mouse Imaging Centre, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | - Angela Caruso
- Department of Cell Biology and Neuroscience, Neurotoxicology and Neuroendocrinology Section, Istituto Superiore Di Sanità, Rome, Italy
- Department of Psychology, School of Behavioural Neuroscience, Sapienza University of Rome, Rome, Italy
| | - Caterina Michetti
- Department of Cell Biology and Neuroscience, Neurotoxicology and Neuroendocrinology Section, Istituto Superiore Di Sanità, Rome, Italy
- Centre for Synaptic Neuroscience and Technology, Istituto Italiano Di Tecnologia, Genova, Italy
| | - Olivier Brock
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Romy Evans
- Centre for Craniofacial and Regenerative Biology, King's College London, London, UK
| | - Fabrizio Rudari
- Centre for Craniofacial and Regenerative Biology, King's College London, London, UK
| | - Alessio Delogu
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Maria Luisa Scattoni
- Department of Cell Biology and Neuroscience, Neurotoxicology and Neuroendocrinology Section, Istituto Superiore Di Sanità, Rome, Italy
| | - Jason P Lerch
- Department of Medical Biophysics, Mouse Imaging Centre, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Cathy Fernandes
- MRC Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
- MRC Centre for Neurodevelopmental Disorders, King's College London, London, UK
| | - M Albert Basson
- Centre for Craniofacial and Regenerative Biology, King's College London, London, UK.
- MRC Centre for Neurodevelopmental Disorders, King's College London, London, UK.
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