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Abstract
Brain development in humans is achieved through precise spatiotemporal genetic control, the mechanisms of which remain largely elusive. Recently, integration of technological advances in human stem cell-based modelling with genome editing has emerged as a powerful platform to establish causative links between genotypes and phenotypes directly in the human system. Here, we review our current knowledge of complex genetic regulation of each key step of human brain development through the lens of evolutionary specialization and neurodevelopmental disorders and highlight the use of human stem cell-derived 2D cultures and 3D brain organoids to investigate human-enriched features and disease mechanisms. We also discuss opportunities and challenges of integrating new technologies to reveal the genetic architecture of human brain development and disorders.
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Affiliation(s)
- Yi Zhou
- Department of Neuroscience and Mahoney Institute for Neurosciences, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Hongjun Song
- Department of Neuroscience and Mahoney Institute for Neurosciences, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Institute for Regenerative Medicine, University of Pennsylvania, Philadelphia, PA, USA
- The Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Guo-Li Ming
- Department of Neuroscience and Mahoney Institute for Neurosciences, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
- Institute for Regenerative Medicine, University of Pennsylvania, Philadelphia, PA, USA.
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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Nadler MJS, Chang W, Ozkaynak E, Huo Y, Nong Y, Boillot M, Johnson M, Moreno A, Matthew P Anderson. Hominoid SVA-lncRNA AK057321 targets human-specific SVA retrotransposons in SCN8A and CDK5RAP2 to initiate neuronal maturation. Commun Biol 2023; 6:347. [PMID: 36997626 PMCID: PMC10063665 DOI: 10.1038/s42003-023-04683-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 03/09/2023] [Indexed: 04/01/2023] Open
Abstract
SINE-VNTR-Alu (SVA) retrotransposons arose and expanded in the genome of hominoid primates concurrent with the slowing of brain maturation. We report genes with intronic SVA transposons are enriched for neurodevelopmental disease and transcribed into long non-coding SVA-lncRNAs. Human-specific SVAs in microcephaly CDK5RAP2 and epilepsy SCN8A gene introns repress their expression via transcription factor ZNF91 to delay neuronal maturation. Deleting the SVA in CDK5RAP2 initiates multi-dimensional and in SCN8A selective sodium current neuronal maturation by upregulating these genes. SVA-lncRNA AK057321 forms RNA:DNA heteroduplexes with the genomic SVAs and upregulates these genes to initiate neuronal maturation. SVA-lncRNA AK057321 also promotes species-specific cortex and cerebellum-enriched expression upregulating human genes with intronic SVAs (e.g., HTT, CHAF1B and KCNJ6) but not mouse orthologs. The diversity of neuronal genes with intronic SVAs suggest this hominoid-specific SVA transposon-based gene regulatory mechanism may act at multiple steps to specialize and achieve neoteny of the human brain.
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Affiliation(s)
- Monica J S Nadler
- Department of Neurology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA, 02115, USA
- Department of Pathology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA, 02115, USA
| | - Weipang Chang
- Department of Neurology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA, 02115, USA
- Department of Pathology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA, 02115, USA
| | - Ekim Ozkaynak
- Department of Neurology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA, 02115, USA
- Department of Pathology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA, 02115, USA
| | - Yuda Huo
- Department of Neurology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA, 02115, USA
- Department of Pathology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA, 02115, USA
- Neuroscience Therapeutic Focus Area, Regeneron, 777 Old Saw Mill River Road, Tarrytown, NY, 10591, USA
| | - Yi Nong
- Department of Neurology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA, 02115, USA
- Department of Pathology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA, 02115, USA
- Neuroscience Therapeutic Focus Area, Regeneron, 777 Old Saw Mill River Road, Tarrytown, NY, 10591, USA
| | - Morgane Boillot
- Department of Neurology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA, 02115, USA
- Department of Pathology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA, 02115, USA
| | - Mark Johnson
- Department of Neurology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA, 02115, USA
- Department of Pathology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA, 02115, USA
| | - Antonio Moreno
- Department of Neurology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA, 02115, USA
- Department of Pathology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA, 02115, USA
| | - Matthew P Anderson
- Department of Neurology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA, 02115, USA.
- Department of Pathology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA, 02115, USA.
- Boston Children's Hospital Intellectual and Developmental Disabilities Research Center, 300 Longwood Avenue, Boston, MA, 02115, USA.
- Program in Neuroscience, Harvard Medical School, 300 Longwood Avenue, Boston, MA, 02115, USA.
- Neuroscience Therapeutic Focus Area, Regeneron, 777 Old Saw Mill River Road, Tarrytown, NY, 10591, USA.
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Romero VI, Arias-Almeida B, Aguiar SA. NSD1 gene evolves under episodic selection within primates and mutations of specific exons in humans cause Sotos syndrome. BMC Genomics 2022; 23:849. [PMID: 36550402 PMCID: PMC9783842 DOI: 10.1186/s12864-022-09071-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 12/05/2022] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Modern human brains and skull shapes differ from other hominids. Brain growth disorders as micro- (ASPM, MCPH1) and macrocephaly (NFIX, GLI3) have been highlighted as relevant for the evolution in humans due to the impact in early brain development. Genes associated with macrocephaly have been reported to cause this change, for example NSD1 which causes Sotos syndrome. RESULTS In this study we performed a systematic literature review, located the reported variants associated to Sotos syndrome along the gene domains, compared the sequences with close primates, calculated their similarity, Ka/Ks ratios, nucleotide diversity and selection, and analyzed the sequence and structural conservation with distant primates. We aimed to understand if NSD1 in humans differs from other primates since the evolution of NSD1 has not been analyzed in primates, nor if the localization of the mutations is limited to humans. Our study found that most variations causing Sotos syndrome are in exon 19, 22 and 10. In the primate comparison we did not detect Ka/Ks ratios > 1, but a high nucleotide diversity with non-synonymous variations in exons 10, 5, 9, 11 and 23, and sites under episodic selection in exon 5 and 23, and human, macaque/colobus/tarsier/galago and tarsier/lemur/colobus. Most of the domains are conserved in distant primates with a particular progressive development from a simple PWWP1 in O. garnetti to a complex structure in Human. CONCLUSION NSD1 is a chromatin modifier that suggests that the selection could influence brain development during modern human evolution and is not present in other primates; however, nowadays the nucleotide diversity is associated with Sotos syndrome.
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Affiliation(s)
- Vanessa I. Romero
- School of Medicine, Universidad San Francisco de Quito, Quito, Ecuador
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Chen J, Ying L, Zeng L, Li C, Jia Y, Yang H, Yang G. The novel compound heterozygous rare variants may impact positively selected regions of TUBGCP6, a microcephaly associated gene. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.1059477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
IntroductionThe microcephaly is a rare and severe disease probably under purifying selection due to the reduction of human brain-size. In contrast, the brain-size enlargement is most probably driven by positive selection, in light of this critical phenotypical innovation during primates and human evolution. Thus, microcephaly-related genes were extensively studied for signals of positive selection. However, whether the pathogenic variants of microcephaly-related genes could affect the regions of positive selection is still unclear.MethodsHere, we conducted whole genome sequencing (WGS) and positive selection analysis.ResultsWe identified novel compound heterozygous variants, p.Y613* and p.E1368K in TUBGCP6, related to microcephaly in a Chinese family. The genotyping and the sanger sequencing revealed the maternal and the paternal origin for the first and second variant, respectively. The p.Y613* occurred before the second and third domain of TUBGCP6 protein, while p.E1368K located within the linker region of the second and third domain. Interestingly, using multiple positive selection analyses, we revealed the potential impacts of these variants on the regions of positive selection of TUBGCP6. The truncating variant p.Y613* could lead to the deletions of two positively selected domains DUF5401 and Spc97_Spc98, while p.E1368K could impose a rare mutation burden on the linker region between these two domains.DiscussionOur investigation expands the list of candidate pathogenic variants of TUBGCP6 that may cause microcephaly. Moreover, the study provides insights into the potential pathogenic effects of variants that truncate or distribute within the positively selected regions.
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Papoulidis I, Eleftheriades M, Manolakos E, Petersen MB, Liappi SM, Konstantinidou A, Papamichail M, Papadopoulos V, Garas A, Sotiriou S, Papastefanou I, Daskalakis G, Ristic A. Prenatal Identification of a Novel Mutation in the MCPH1 Gene Associated with Autosomal Recessive Primary Microcephaly (MCPH) Using Next Generation Sequencing (NGS): A Case Report and Review of the Literature. CHILDREN (BASEL, SWITZERLAND) 2022; 9:children9121879. [PMID: 36553323 PMCID: PMC9776937 DOI: 10.3390/children9121879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 11/19/2022] [Accepted: 11/27/2022] [Indexed: 12/03/2022]
Abstract
BACKGROUND MCPH1 is known as the microcephalin gene (OMIM: *607117), of which the encoding protein is a basic regulator of chromosome condensation (BCRT-BRCA1 C-terminus). The microcephalin protein is made up of three BCRT domains and conserved tandem repeats of interacting phospho-peptides. There is a strong connection between mutations of the MCPH1 gene and reduced brain growth. Specifically, individuals with such mutations have underdeveloped brains, varying levels of mental retardation, delayed speech and poor language skills. METHODS In this article, a family with two affected fetuses presenting a mutation of the MCPH1 gene is reported. During the first trimester ultrasound of the second pregnancy, the measure of nuchal translucency was increased (NT = 3.1 mm) and, therefore, the risk for chromosomal abnormalities was high. Chorionic villi sampling (CVS) was then performed. Afterwards, fetal karyotyping and Next Generation Sequencing were carried out. Afterwards, NGS was also performed in a preserved sample of the first fetus which was terminated due to microcephaly. RESULTS In this case, the fetuses had a novel homozygous mutation of the MCPH1 gene (c.348del). Their parents were heterozygous for the mutation. The fetuses showed severe microcephaly. Because of the splice sites in introns, this mutation causes the forming of dysfunctional proteins which lack crucial domains of the C-terminus. CONCLUSION Our findings portray an association between the new MCPH1 mutation (c.348del) and the clinical features of autosomal recessive primary microcephaly (MCPH), contributing to a broader spectrum related to these pathologies. To our knowledge, this is the first prenatal diagnosis of MCPH due to a novel MCPH1 mutation.
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Affiliation(s)
- Ioannis Papoulidis
- Access to Genome P.C., Clinical Laboratory Genetics, Lampsakou 11, 11528 Thessaloniki, Greece
| | - Makarios Eleftheriades
- Second Department of Obstetrics and Gynaecology, Aretaieion Hospital, Medical School, National and Kapodistrian University of Athens, 112527 Athens, Greece
- Correspondence: (M.E.); (M.P.)
| | - Emmanouil Manolakos
- Access to Genome P.C., Clinical Laboratory Genetics, Lampsakou 11, 11528 Thessaloniki, Greece
- Department of Medical Genetics, University of Cagliari, Binaghi Hospital, 09124 Cagliari, Italy
| | - Michael B. Petersen
- Access to Genome P.C., Clinical Laboratory Genetics, Lampsakou 11, 11528 Thessaloniki, Greece
| | - Simoni Marina Liappi
- Access to Genome P.C., Clinical Laboratory Genetics, Lampsakou 11, 11528 Thessaloniki, Greece
| | - Anastasia Konstantinidou
- 1st Department of Pathology, School of Medicine, National and Kapodistrian University of Athens, 11528 Athens, Greece
| | - Maria Papamichail
- Postgraduate Programme “Maternal Fetal Medicine”, Medical School, National and Kapodistrian University of Athens, 11528 Athens, Greece
- Correspondence: (M.E.); (M.P.)
| | | | - Antonios Garas
- Department of Gynecology, Larissa Medical School, University of Thessaly, 38221 Larissa, Greece
| | - Sotirios Sotiriou
- Department of Clinical Embryology, Larissa Medical School, University of Thessaly, 41334 Larissa, Greece
| | | | - Georgios Daskalakis
- First Department of Obstetrics and Gynaecology, “Alexandra” Maternity Hospital, Medical School, National and Kapodistrian University of Athens, 15772 Athens, Greece
| | - Aleksandar Ristic
- Obstetric and Gynecological Clinic Narodni Front, 11000 Belgrade, Serbia
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Abstract
The current understanding of neurological diseases is derived mostly from direct analysis of patients and from animal models of disease. However, most patient studies do not capture the earliest stages of disease development and offer limited opportunities for experimental intervention, so rarely yield complete mechanistic insights. The use of animal models relies on evolutionary conservation of pathways involved in disease and is limited by an inability to recreate human-specific processes. In vitro models that are derived from human pluripotent stem cells cultured in 3D have emerged as a new model system that could bridge the gap between patient studies and animal models. In this Review, we summarize how such organoid models can complement classical approaches to accelerate neurological research. We describe our current understanding of neurodevelopment and how this process differs between humans and other animals, making human-derived models of disease essential. We discuss different methodologies for producing organoids and how organoids can be and have been used to model neurological disorders, including microcephaly, Zika virus infection, Alzheimer disease and other neurodegenerative disorders, and neurodevelopmental diseases, such as Timothy syndrome, Angelman syndrome and tuberous sclerosis. We also discuss the current limitations of organoid models and outline how organoids can be used to revolutionize research into the human brain and neurological diseases. In this Review, Eichmüller and Knoblich discuss how human brain organoids can recapitulate the unique processes that occur in human brain development and how they can complement classical approaches to revolutionize research into neurological diseases. Development of the human brain involves unique processes that are relevant to neurological disease but cannot be studied in animal models, so alternative model systems are required. Organoids are 3D human cell culture models that originate from pluripotent stem cells and recapitulate the hallmarks of human neurodevelopment, enabling studies of human brain development in vitro. Specific mutations can be introduced into organoids to study their effects on neurodevelopment; combined with high-throughput screening methods, this approach can determine the disease relevance of mutations in human tissue. To study specific diseases, brain organoids can be generated from induced pluripotent stem cells from individual patients, thereby preserving the specific genetic background of the individual and generating an insightful model. Through recapitulation of previously inaccessible periods of human brain development, brain organoids have enabled identification of novel mechanisms that underlie neurodevelopmental, neurodegenerative and infectious diseases. Combining organoids, patient research and animal models enables us to take full advantage of each of these systems and will provide unprecedented insights into neurodevelopment and neurological diseases.
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Equivocal evidence for a link between megalencephaly-related genes and primate brain size evolution. Sci Rep 2022; 12:10902. [PMID: 35764790 PMCID: PMC9239989 DOI: 10.1038/s41598-022-12953-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Accepted: 05/19/2022] [Indexed: 11/08/2022] Open
Abstract
A large brain is a defining feature of modern humans, and much work has been dedicated to exploring the molecular underpinnings of this trait. Although numerous studies have focused on genes associated with human microcephaly, no studies have explicitly focused on genes associated with megalencephaly. Here, we investigate 16 candidate genes that have been linked to megalencephaly to determine if: (1) megalencephaly-associated genes evolved under positive selection across primates; and (2) selection pressure on megalencephaly-associated genes is linked to primate brain size. We found evidence for positive selection for only one gene, OFD1, with 1.8% of the sites estimated to have dN/dS values greater than 1; however, we did not detect a relationship between selection pressure on this gene and brain size across species, suggesting that selection for changes to non-brain size traits drove evolutionary changes to this gene. In fact, our primary analyses did not identify significant associations between selection pressure and brain size for any candidate genes. While we did detect positive associations for two genes (GPC3 and TBC1D7) when two phyletic dwarfs (i.e., species that underwent recent evolutionary decreases in brain size) were excluded, these associations did not withstand FDR correction. Overall, these results suggest that sequence alterations to megalencephaly-associated genes may have played little to no role in primate brain size evolution, possibly due to the highly pleiotropic effects of these genes. Future comparative studies of gene expression levels may provide further insights. This study enhances our understanding of the genetic underpinnings of brain size evolution in primates and identifies candidate genes that merit further exploration.
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Ossola C, Kalebic N. Roots of the Malformations of Cortical Development in the Cell Biology of Neural Progenitor Cells. Front Neurosci 2022; 15:817218. [PMID: 35069108 PMCID: PMC8766818 DOI: 10.3389/fnins.2021.817218] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 12/14/2021] [Indexed: 12/13/2022] Open
Abstract
The cerebral cortex is a structure that underlies various brain functions, including cognition and language. Mammalian cerebral cortex starts developing during the embryonic period with the neural progenitor cells generating neurons. Newborn neurons migrate along progenitors’ radial processes from the site of their origin in the germinal zones to the cortical plate, where they mature and integrate in the forming circuitry. Cell biological features of neural progenitors, such as the location and timing of their mitoses, together with their characteristic morphologies, can directly or indirectly regulate the abundance and the identity of their neuronal progeny. Alterations in the complex and delicate process of cerebral cortex development can lead to malformations of cortical development (MCDs). They include various structural abnormalities that affect the size, thickness and/or folding pattern of the developing cortex. Their clinical manifestations can entail a neurodevelopmental disorder, such as epilepsy, developmental delay, intellectual disability, or autism spectrum disorder. The recent advancements of molecular and neuroimaging techniques, along with the development of appropriate in vitro and in vivo model systems, have enabled the assessment of the genetic and environmental causes of MCDs. Here we broadly review the cell biological characteristics of neural progenitor cells and focus on those features whose perturbations have been linked to MCDs.
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9
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Dediu D. Tone and genes: New cross-linguistic data and methods support the weak negative effect of the "derived" allele of ASPM on tone, but not of Microcephalin. PLoS One 2021; 16:e0253546. [PMID: 34191836 PMCID: PMC8244921 DOI: 10.1371/journal.pone.0253546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 06/08/2021] [Indexed: 11/19/2022] Open
Abstract
While it is generally accepted that language and speech have genetic foundations, and that the widespread inter-individual variation observed in many of their aspects is partly driven by variation in genes, it is much less clear if differences between languages may also be partly rooted in our genes. One such proposal is that the population frequencies of the so-called "derived" alleles of two genes involved in brain growth and development, ASPM and Microcephalin, are related to the probability of speaking a tone language or not. The original study introducing this proposal used a cross-linguistic statistical approach, showing that these associations are "special" when compared with many other possible relationships between genetic variants and linguistic features. Recent experimental evidence supports strongly a negative effect of the "derived" allele of ASPM on tone perception and/or processing within individuals, but failed to find any effect for Microcephalin. Motivated by these experimental findings, I conduct here a cross-linguistic statistical test, using a larger and updated dataset of 175 samples from 129 unique (meta)populations, and a battery of methods including mixed-effects regression (Bayesian and maximum-likelihood), mediation and path analysis, decision trees and random forests, using permutations and restricted sampling to control for the confounding effects of genealogy (language families) and contact (macroareas). Overall, the results support a negative weak effect of ASPM-D against the presence of tone above and beyond the strong confounding influences of genealogy and contact, but they suggest that the original association between tone and MCPH1 might have been a false positive, explained by differences between populations and languages within and outside Africa. Thus, these cross-linguistic population-scale statistical results are fully consonant with the inter-individual-level experimental results, and suggest that the observed linguistic diversity may be, at least in some cases, partly driven by genetic diversity.
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Affiliation(s)
- Dan Dediu
- Laboratoire Dynamique Du Language (DDL) UMR5596, Université Lumière Lyon 2, Lyon, France
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Genomic selection signatures in autism spectrum disorder identifies cognitive genomic tradeoff and its relevance in paradoxical phenotypes of deficits versus potentialities. Sci Rep 2021; 11:10245. [PMID: 33986442 PMCID: PMC8119484 DOI: 10.1038/s41598-021-89798-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 04/26/2021] [Indexed: 11/18/2022] Open
Abstract
Autism spectrum disorder (ASD) is a heterogeneous neurodevelopmental disorder characterized by paradoxical phenotypes of deficits as well as gain in brain function. To address this a genomic tradeoff hypothesis was tested and followed up with the biological interaction and evolutionary significance of positively selected ASD risk genes. SFARI database was used to retrieve the ASD risk genes while for population datasets 1000 genome data was used. Common risk SNPs were subjected to machine learning as well as independent tests for selection, followed by Bayesian analysis to identify the cumulative effect of selection on risk SNPs. Functional implication of these positively selected risk SNPs was assessed and subjected to ontology analysis, pertaining to their interaction and enrichment of biological and cellular functions. This was followed by comparative analysis with the ancient genomes to identify their evolutionary patterns. Our results identified significant positive selection signals in 18 ASD risk SNPs. Functional and ontology analysis indicate the role of biological and cellular processes associated with various brain functions. The core of the biological interaction network constitutes genes for cognition and learning while genes in the periphery of the network had direct or indirect impact on brain function. Ancient genome analysis identified de novo and conserved evolutionary selection clusters. The de-novo evolutionary cluster represented genes involved in cognitive function. Relative enrichment of the ASD risk SNPs from the respective evolutionary cluster or biological interaction networks may help in addressing the phenotypic diversity in ASD. This cognitive genomic tradeoff signatures impacting the biological networks can explain the paradoxical phenotypes in ASD.
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11
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Pervaiz N, Kang H, Bao Y, Abbasi AA. Molecular evolutionary analysis of human primary microcephaly genes. BMC Ecol Evol 2021; 21:76. [PMID: 33941077 PMCID: PMC8091745 DOI: 10.1186/s12862-021-01801-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 04/22/2021] [Indexed: 12/05/2022] Open
Abstract
Background There has been a rapid increase in the brain size relative to body size during mammalian evolutionary history. In particular, the enlarged and globular brain is the most distinctive anatomical feature of modern humans that set us apart from other extinct and extant primate species. Genetic basis of large brain size in modern humans has largely remained enigmatic. Genes associated with the pathological reduction of brain size (primary microcephaly-MCPH) have the characteristics and functions to be considered ideal candidates to unravel the genetic basis of evolutionary enlargement of human brain size. For instance, the brain size of microcephaly patients is similar to the brain size of Pan troglodyte and the very early hominids like the Sahelanthropus tchadensis and Australopithecus afarensis. Results The present study investigates the molecular evolutionary history of subset of autosomal recessive primary microcephaly (MCPH) genes; CEP135, ZNF335, PHC1, SASS6, CDK6, MFSD2A, CIT, and KIF14 across 48 mammalian species. Codon based substitutions site analysis indicated that ZNF335, SASS6, CIT, and KIF14 have experienced positive selection in eutherian evolutionary history. Estimation of divergent selection pressure revealed that almost all of the MCPH genes analyzed in the present study have maintained their functions throughout the history of placental mammals. Contrary to our expectations, human-specific adoptive evolution was not detected for any of the MCPH genes analyzed in the present study. Conclusion Based on these data it can be inferred that protein-coding sequence of MCPH genes might not be the sole determinant of increase in relative brain size during primate evolutionary history. Supplementary Information The online version contains supplementary material available at 10.1186/s12862-021-01801-0.
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Affiliation(s)
- Nashaiman Pervaiz
- National Center for Bioinformatics, Program of Comparative and Evolutionary Genomics, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, 45320, Pakistan
| | - Hongen Kang
- China National Center for Bioinformation and National Genomics Data Center, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Yiming Bao
- China National Center for Bioinformation and National Genomics Data Center, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Amir Ali Abbasi
- National Center for Bioinformatics, Program of Comparative and Evolutionary Genomics, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, 45320, Pakistan.
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12
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Abstract
The dramatic evolutionary expansion of the neocortex, together with a proliferation of specialized cortical areas, is believed to underlie the emergence of human cognitive abilities. In a broader phylogenetic context, however, neocortex evolution in mammals, including humans, is remarkably conservative, characterized largely by size variations on a shared six-layered neuronal architecture. By contrast, the telencephalon in non-mammalian vertebrates, including reptiles, amphibians, bony and cartilaginous fishes, and cyclostomes, features a great variety of very different tissue structures. Our understanding of the evolutionary relationships of these telencephalic structures, especially those of basally branching vertebrates and invertebrate chordates, remains fragmentary and is impeded by conceptual obstacles. To make sense of highly divergent anatomies requires a hierarchical view of biological organization, one that permits the recognition of homologies at multiple levels beyond neuroanatomical structure. Here we review the origin and diversification of the telencephalon with a focus on key evolutionary innovations shaping the neocortex at multiple levels of organization.
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Affiliation(s)
- Steven D Briscoe
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany.
| | - Clifton W Ragsdale
- Department of Neurobiology, University of Chicago, Chicago, IL 60637, USA; Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL 60637, USA
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13
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Doan RN, Shin T, Walsh CA. Evolutionary Changes in Transcriptional Regulation: Insights into Human Behavior and Neurological Conditions. Annu Rev Neurosci 2019; 41:185-206. [PMID: 29986162 DOI: 10.1146/annurev-neuro-080317-062104] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Understanding the biological basis for human-specific cognitive traits presents both immense challenges and unique opportunities. Although the question of what makes us human has been investigated with several different methods, the rise of comparative genomics, epigenomics, and medical genetics has provided tools to help narrow down and functionally assess the regions of the genome that seem evolutionarily relevant along the human lineage. In this review, we focus on how medical genetic cases have provided compelling functional evidence for genes and loci that appear to have interesting evolutionary signatures in humans. Furthermore, we examine a special class of noncoding regions, human accelerated regions (HARs), that have been suggested to show human-lineage-specific divergence, and how the use of clinical and population data has started to provide functional information to examine these regions. Finally, we outline methods that provide new insights into functional noncoding sequences in evolution.
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Affiliation(s)
- Ryan N Doan
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, Massachusetts 02115, USA; .,Allen Discovery Center for Human Brain Evolution, Boston Children's Hospital, Boston, Massachusetts 02115, USA.,Howard Hughes Medical Institute, Boston Children's Hospital, Boston, Massachusetts 02115, USA
| | - Taehwan Shin
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, Massachusetts 02115, USA; .,Allen Discovery Center for Human Brain Evolution, Boston Children's Hospital, Boston, Massachusetts 02115, USA
| | - Christopher A Walsh
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, Massachusetts 02115, USA; .,Allen Discovery Center for Human Brain Evolution, Boston Children's Hospital, Boston, Massachusetts 02115, USA.,Howard Hughes Medical Institute, Boston Children's Hospital, Boston, Massachusetts 02115, USA.,Departments of Pediatrics and Neurology, Harvard Medical School, Boston, Massachusetts 02138, USA
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14
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Singh SV, Staes N, Guevara EE, Schapiro SJ, Ely JJ, Hopkins WD, Sherwood CC, Bradley BJ. Evolution of ASPM coding variation in apes and associations with brain structure in chimpanzees. GENES BRAIN AND BEHAVIOR 2019; 18:e12582. [PMID: 31119860 DOI: 10.1111/gbb.12582] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2019] [Revised: 05/07/2019] [Accepted: 05/21/2019] [Indexed: 12/21/2022]
Abstract
Studying genetic mechanisms underlying primate brain morphology can provide insight into the evolution of human brain structure and cognition. In humans, loss-of-function mutations in the gene coding for ASPM (Abnormal Spindle Microtubule Assembly) have been associated with primary microcephaly, which is defined by a significantly reduced brain volume, intellectual disability and delayed development. However, less is known about the effects of common ASPM variation in humans and other primates. In this study, we characterized the degree of coding variation at ASPM in a large sample of chimpanzees (N = 241), and examined potential associations between genotype and various measures of brain morphology. We identified and genotyped five non-synonymous polymorphisms in exons 3 (V588G), 18 (Q2772K, K2796E, C2811Y) and 27 (I3427V). Using T1-weighted magnetic resonance imaging of brains, we measured total brain volume, cerebral gray and white matter volume, cerebral ventricular volume, and cortical surface area in the same chimpanzees. We found a potential association between ASPM V588G genotype and cerebral ventricular volume but not with the other measures. Additionally, we found that chimpanzee, bonobo, and human lineages each independently show a signature of accelerated ASPM protein evolution. Overall, our results suggest the potential effects of ASPM variation on cerebral cortical development, and emphasize the need for further functional studies. These results are the first evidence suggesting ASPM variation might play a role in shaping natural variation in brain structure in nonhuman primates.
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Affiliation(s)
- Sheel V Singh
- Center for the Advanced Study of Human Paleobiology, Department of Anthropology, The George Washington University, Washington, District of Columbia
| | - Nicky Staes
- Center for the Advanced Study of Human Paleobiology, Department of Anthropology, The George Washington University, Washington, District of Columbia.,Behavioural Ecology & Ecophysiology Group, Department of Biology, University of Antwerp, Antwerp, Belgium.,Centre for Research and Conservation, Royal Zoological Society of Antwerp, Antwerp, Belgium
| | - Elaine E Guevara
- Center for the Advanced Study of Human Paleobiology, Department of Anthropology, The George Washington University, Washington, District of Columbia
| | - Steven J Schapiro
- Michael E. Keeling Center for Comparative Medicine and Research, University of Texas MD Anderson Cancer Center, Bastrop, Texas
| | | | - William D Hopkins
- Michael E. Keeling Center for Comparative Medicine and Research, University of Texas MD Anderson Cancer Center, Bastrop, Texas
| | - Chet C Sherwood
- Center for the Advanced Study of Human Paleobiology, Department of Anthropology, The George Washington University, Washington, District of Columbia
| | - Brenda J Bradley
- Center for the Advanced Study of Human Paleobiology, Department of Anthropology, The George Washington University, Washington, District of Columbia
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15
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Abstract
During the course of evolution the human brain has increased in size and complexity, ultimately these differences are the result of changes at the genetic level. Identifying and characterizing molecular evolution requires an understanding of both the genetic underpinning of the system as well as the comparative genetic tools to identify signatures of selection. This chapter aims to describe our current understanding of the genetics of human brain evolution. Primarily this is the story of the evolution of the human brain since our last common ape ancestor, but where relevant we will also discuss changes that are unique to the primate brain (compared to other mammals) or various other lineages in the evolution of humans more generally. It will focus on genetic changes that both directly affected the development and function of the brain as well as those that have indirectly influenced brain evolution through both prenatal and postnatal environment. This review is not meant to be exhaustive, but rather to begin to construct a general framework for understanding the full array of data being generated.
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Affiliation(s)
- Eric J Vallender
- University of Mississippi Medical Center, Jackson, MS, United States; Tulane National Primate Research Center, Covington, LA, United States.
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16
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Comprehensive review on the molecular genetics of autosomal recessive primary microcephaly (MCPH). Genet Res (Camb) 2018; 100:e7. [PMID: 30086807 DOI: 10.1017/s0016672318000046] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Primary microcephaly (MCPH) is an autosomal recessive sporadic neurodevelopmental ailment with a trivial head size characteristic that is below 3-4 standard deviations. MCPH is the smaller upshot of an architecturally normal brain; a significant decrease in size is seen in the cerebral cortex. At birth MCPH presents with non-progressive mental retardation, while secondary microcephaly (onset after birth) presents with and without other syndromic features. MCPH is a neurogenic mitotic syndrome nevertheless pretentious patients demonstrate normal neuronal migration, neuronal apoptosis and neural function. Eighteen MCPH loci (MCPH1-MCPH18) have been mapped to date from various populations around the world and contain the following genes: Microcephalin, WDR62, CDK5RAP2, CASC5, ASPM, CENPJ, STIL, CEP135, CEP152, ZNF335, PHC1, CDK6, CENPE, SASS6, MFSD2A, ANKLE2, CIT and WDFY3, clarifying our understanding about the molecular basis of microcephaly genetic disorder. It has previously been reported that phenotype disease is caused by MCB gene mutations and the causes of this phenotype are disarrangement of positions and organization of chromosomes during the cell cycle as a result of mutated DNA, centriole duplication, neurogenesis, neuronal migration, microtubule dynamics, transcriptional control and the cell cycle checkpoint having some invisible centrosomal process that can manage the number of neurons that are produced by neuronal precursor cells. Furthermore, researchers inform us about the clinical management of families that are suffering from MCPH. Establishment of both molecular understanding and genetic advocating may help to decrease the rate of this ailment. This current review study examines newly identified genes along with previously identified genes involved in autosomal recessive MCPH.
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17
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Abstract
Primary microcephaly (MCPH, for "microcephaly primary hereditary") is a disorder of brain development that results in a head circumference more than 3 standard deviations below the mean for age and gender. It has a wide variety of causes, including toxic exposures, in utero infections, and metabolic conditions. While the genetic microcephaly syndromes are relatively rare, studying these syndromes can reveal molecular mechanisms that are critical in the regulation of neural progenitor cells, brain size, and human brain evolution. Many of the causative genes for MCPH encode centrosomal proteins involved in centriole biogenesis. However, other MCPH genes fall under different mechanistic categories, notably DNA replication and repair. Recent gene discoveries and functional studies have implicated novel cellular processes, such as cytokinesis, centromere and kinetochore function, transmembrane or intracellular transport, Wnt signaling, and autophagy, as well as the apical polarity complex. Thus, MCPH genes implicate a wide variety of molecular and cellular mechanisms in the regulation of cerebral cortical size during development.
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Affiliation(s)
- Divya Jayaraman
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, and Howard Hughes Medical Institute, Boston Children's Hospital, Boston, Massachusetts 02115, USA.,Harvard-MIT MD-PhD Program, Harvard Medical School, Boston, Massachusetts 02115, USA.,Current affiliation: Boston Combined Residency Program (Child Neurology), Boston Children's Hospital, Boston, Massachusetts 02115, USA;
| | - Byoung-Il Bae
- Department of Neurosurgery, Yale University School of Medicine, New Haven, Connecticut 06510, USA;
| | - Christopher A Walsh
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, and Howard Hughes Medical Institute, Boston Children's Hospital, Boston, Massachusetts 02115, USA.,Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142, USA.,Departments of Pediatrics and Neurology, Harvard Medical School, Boston, Massachusetts 02115, USA;
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18
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Johnson MB, Sun X, Kodani A, Borges-Monroy R, Girskis KM, Ryu SC, Wang PP, Patel K, Gonzalez DM, Woo YM, Yan Z, Liang B, Smith RS, Chatterjee M, Coman D, Papademetris X, Staib LH, Hyder F, Mandeville JB, Grant PE, Im K, Kwak H, Engelhardt JF, Walsh CA, Bae BI. Aspm knockout ferret reveals an evolutionary mechanism governing cerebral cortical size. Nature 2018; 556:370-375. [PMID: 29643508 PMCID: PMC6095461 DOI: 10.1038/s41586-018-0035-0] [Citation(s) in RCA: 102] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 02/22/2018] [Indexed: 12/17/2022]
Abstract
The human cerebral cortex is distinguished by its large size and abundant
gyrification, or folding, yet the evolutionary mechanisms driving cortical size
and structure are unknown. While genes essential for cortical developmental
expansion have been identified from the genetics of human primary microcephaly
(“small head”, associated with reduced brain size and
intellectual disability)1,
studies of these genes in mice, whose smooth cortex is one thousand times
smaller than that of humans, have provided limited insight. Mutations of
abnormal spindle-like microcephaly-associated
(ASPM), the most common recessive microcephaly gene, reduce
cortical volume by ≥50% in humans2–4, but have little effect in mice5–9, likely reflecting evolutionarily divergent functions of
ASPM10,11. We used genome editing to
create a germline knockout (KO) of Aspm in the ferret
(Mustela putorius furo), a species with a larger, gyrified
cortex and greater neural progenitor cell (NPC) diversity12–14 than mice, and closer Aspm protein sequence homology to
human. Aspm KO ferrets exhibit severe microcephaly
(25–40% decreases in brain weight), reflecting reduced cortical
surface area without significant change in cortical thickness, as in human
patients3,4, suggesting loss of “cortical
units”. The mutant ferret fetal cortex displays a massive premature
displacement of ventricular radial glial cells (VRG) to the outer subventricular
zone (OSVZ), where many resemble outer radial glia (ORG), an NPC subtype
essentially absent in mice and implicated in cerebral cortical expansion in
primates12–16. These data suggest an
evolutionary mechanism whereby Aspm regulates cortical expansion by controlling
the affinity of VRG for the ventricular surface, thus modulating the ratio of
VRG, the most undifferentiated cell type, to ORG, a more differentiated
progenitor.
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Affiliation(s)
- Matthew B Johnson
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.,Howard Hughes Medical Institute, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Xingshen Sun
- Department of Anatomy and Cell Biology, Center for Gene Therapy, University of Iowa, Iowa City, IA, USA.,Center for Gene Therapy, University of Iowa, Iowa City, IA, USA.,National Ferret Resource and Research Center, University of Iowa, Iowa City, IA, USA
| | - Andrew Kodani
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.,Howard Hughes Medical Institute, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Rebeca Borges-Monroy
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.,Howard Hughes Medical Institute, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Kelly M Girskis
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.,Howard Hughes Medical Institute, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Steven C Ryu
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.,Howard Hughes Medical Institute, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Peter P Wang
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.,Howard Hughes Medical Institute, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Komal Patel
- Department of Neurosurgery, School of Medicine, Yale University, New Haven, CT, USA
| | - Dilenny M Gonzalez
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.,Howard Hughes Medical Institute, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Yu Mi Woo
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
| | - Ziying Yan
- Department of Anatomy and Cell Biology, Center for Gene Therapy, University of Iowa, Iowa City, IA, USA.,Center for Gene Therapy, University of Iowa, Iowa City, IA, USA.,National Ferret Resource and Research Center, University of Iowa, Iowa City, IA, USA
| | - Bo Liang
- Department of Anatomy and Cell Biology, Center for Gene Therapy, University of Iowa, Iowa City, IA, USA.,Center for Gene Therapy, University of Iowa, Iowa City, IA, USA.,National Ferret Resource and Research Center, University of Iowa, Iowa City, IA, USA
| | - Richard S Smith
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.,Howard Hughes Medical Institute, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Manavi Chatterjee
- Department of Neurosurgery, School of Medicine, Yale University, New Haven, CT, USA
| | - Daniel Coman
- Magnetic Resonance Research Center (MRRC), Yale University, New Haven, CT, USA.,Quantitative Neuroscience with Magnetic Resonance (QNMR) Core Center, Yale University, New Haven, CT, USA.,Department of Radiology & Biomedical Imaging, Yale University, New Haven, CT, USA
| | - Xenophon Papademetris
- Quantitative Neuroscience with Magnetic Resonance (QNMR) Core Center, Yale University, New Haven, CT, USA.,Department of Radiology & Biomedical Imaging, Yale University, New Haven, CT, USA.,Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - Lawrence H Staib
- Department of Radiology & Biomedical Imaging, Yale University, New Haven, CT, USA.,Department of Biomedical Engineering, Yale University, New Haven, CT, USA.,Department of Electrical Engineering, Yale University, New Haven, CT, USA
| | - Fahmeed Hyder
- Magnetic Resonance Research Center (MRRC), Yale University, New Haven, CT, USA.,Quantitative Neuroscience with Magnetic Resonance (QNMR) Core Center, Yale University, New Haven, CT, USA.,Department of Radiology & Biomedical Imaging, Yale University, New Haven, CT, USA.,Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - Joseph B Mandeville
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, USA
| | - P Ellen Grant
- Division of Newborn Medicine, Fetal Neonatal Neuroimaging and Developmental Science Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Kiho Im
- Division of Newborn Medicine, Fetal Neonatal Neuroimaging and Developmental Science Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Hojoong Kwak
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
| | - John F Engelhardt
- Department of Anatomy and Cell Biology, Center for Gene Therapy, University of Iowa, Iowa City, IA, USA.,Center for Gene Therapy, University of Iowa, Iowa City, IA, USA.,National Ferret Resource and Research Center, University of Iowa, Iowa City, IA, USA
| | - Christopher A Walsh
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA. .,Howard Hughes Medical Institute, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.
| | - Byoung-Il Bae
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA. .,Howard Hughes Medical Institute, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA. .,Department of Neurosurgery, School of Medicine, Yale University, New Haven, CT, USA.
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19
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Montgomery SH, Mundy NI, Barton RA. Brain evolution and development: adaptation, allometry and constraint. Proc Biol Sci 2017; 283:rspb.2016.0433. [PMID: 27629025 DOI: 10.1098/rspb.2016.0433] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 08/19/2016] [Indexed: 01/08/2023] Open
Abstract
Phenotypic traits are products of two processes: evolution and development. But how do these processes combine to produce integrated phenotypes? Comparative studies identify consistent patterns of covariation, or allometries, between brain and body size, and between brain components, indicating the presence of significant constraints limiting independent evolution of separate parts. These constraints are poorly understood, but in principle could be either developmental or functional. The developmental constraints hypothesis suggests that individual components (brain and body size, or individual brain components) tend to evolve together because natural selection operates on relatively simple developmental mechanisms that affect the growth of all parts in a concerted manner. The functional constraints hypothesis suggests that correlated change reflects the action of selection on distributed functional systems connecting the different sub-components, predicting more complex patterns of mosaic change at the level of the functional systems and more complex genetic and developmental mechanisms. These hypotheses are not mutually exclusive but make different predictions. We review recent genetic and neurodevelopmental evidence, concluding that functional rather than developmental constraints are the main cause of the observed patterns.
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Affiliation(s)
- Stephen H Montgomery
- Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK
| | - Nicholas I Mundy
- Department of Zoology, University of Cambridge, St Andrews Street, Cambridge CB2 3EJ, UK
| | - Robert A Barton
- Evolutionary Anthropology Research Group, Durham University, Dawson Building, South Road, Durham DH1 3LE, UK
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20
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Abstract
A suite of recent studies has reported positive genetic correlations between autism risk and measures of mental ability. These findings indicate that alleles for autism overlap broadly with alleles for high intelligence, which appears paradoxical given that autism is characterized, overall, by below-average IQ. This paradox can be resolved under the hypothesis that autism etiology commonly involves enhanced, but imbalanced, components of intelligence. This hypothesis is supported by convergent evidence showing that autism and high IQ share a diverse set of convergent correlates, including large brain size, fast brain growth, increased sensory and visual-spatial abilities, enhanced synaptic functions, increased attentional focus, high socioeconomic status, more deliberative decision-making, profession and occupational interests in engineering and physical sciences, and high levels of positive assortative mating. These findings help to provide an evolutionary basis to understanding autism risk as underlain in part by dysregulation of intelligence, a core human-specific adaptation. In turn, integration of studies on intelligence with studies of autism should provide novel insights into the neurological and genetic causes of high mental abilities, with important implications for cognitive enhancement, artificial intelligence, the relationship of autism with schizophrenia, and the treatment of both autism and intellectual disability.
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Affiliation(s)
- Bernard J Crespi
- Department of Biological Sciences and Human Evolutionary Studies Program, Simon Fraser University Burnaby, BC, Canada
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21
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Silver DL. Genomic divergence and brain evolution: How regulatory DNA influences development of the cerebral cortex. Bioessays 2015; 38:162-71. [PMID: 26642006 DOI: 10.1002/bies.201500108] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The cerebral cortex controls our most distinguishing higher cognitive functions. Human-specific gene expression differences are abundant in the cerebral cortex, yet we have only begun to understand how these variations impact brain function. This review discusses the current evidence linking non-coding regulatory DNA changes, including enhancers, with neocortical evolution. Functional interrogation using animal models reveals converging roles for our genome in key aspects of cortical development including progenitor cell cycle and neuronal signaling. New technologies, including iPS cells and organoids, offer potential alternatives to modeling evolutionary modifications in a relevant species context. Several diseases rooted in the cerebral cortex uniquely manifest in humans compared to other primates, thus highlighting the importance of understanding human brain differences. Future studies of regulatory loci, including those implicated in disease, will collectively help elucidate key cellular and genetic mechanisms underlying our distinguishing cognitive traits.
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Affiliation(s)
- Debra L Silver
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, USA.,Department of Cell Biology, Duke University Medical Center, Durham, NC, USA.,Department of Neurobiology, Duke University Medical Center, Durham, NC, USA.,Duke Institute for Brain Sciences, Duke University Medical Center, Durham, NC, USA
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22
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Williams SE, Garcia I, Crowther AJ, Li S, Stewart A, Liu H, Lough KJ, O'Neill S, Veleta K, Oyarzabal EA, Merrill JR, Shih YYI, Gershon TR. Aspm sustains postnatal cerebellar neurogenesis and medulloblastoma growth in mice. Development 2015; 142:3921-32. [PMID: 26450969 DOI: 10.1242/dev.124271] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Accepted: 09/28/2015] [Indexed: 01/06/2023]
Abstract
Alterations in genes that regulate brain size may contribute to both microcephaly and brain tumor formation. Here, we report that Aspm, a gene that is mutated in familial microcephaly, regulates postnatal neurogenesis in the cerebellum and supports the growth of medulloblastoma, the most common malignant pediatric brain tumor. Cerebellar granule neuron progenitors (CGNPs) express Aspm when maintained in a proliferative state by sonic hedgehog (Shh) signaling, and Aspm is expressed in Shh-driven medulloblastoma in mice. Genetic deletion of Aspm reduces cerebellar growth, while paradoxically increasing the mitotic rate of CGNPs. Aspm-deficient CGNPs show impaired mitotic progression, altered patterns of division orientation and differentiation, and increased DNA damage, which causes progenitor attrition through apoptosis. Deletion of Aspm in mice with Smo-induced medulloblastoma reduces tumor growth and increases DNA damage. Co-deletion of Aspm and either of the apoptosis regulators Bax or Trp53 (also known as p53) rescues the survival of neural progenitors and reduces the growth restriction imposed by Aspm deletion. Our data show that Aspm functions to regulate mitosis and to mitigate DNA damage during CGNP cell division, causes microcephaly through progenitor apoptosis when mutated, and sustains tumor growth in medulloblastoma.
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Affiliation(s)
- Scott E Williams
- Department of Pathology & Laboratory Medicine, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
| | - Idoia Garcia
- Department of Neurology, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
| | - Andrew J Crowther
- Department of Neurology, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA UNC Neuroscience Center, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
| | - Shiyi Li
- Department of Neurology, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
| | - Alyssa Stewart
- Department of Neurology, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
| | - Hedi Liu
- Department of Neurology, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
| | - Kendall J Lough
- Department of Pathology & Laboratory Medicine, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
| | - Sean O'Neill
- Department of Neurology, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
| | - Katherine Veleta
- Department of Neurology, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA UNC Neuroscience Center, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
| | - Esteban A Oyarzabal
- Department of Neurology, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA UNC Neuroscience Center, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
| | - Joseph R Merrill
- Biomedical Research Imaging Center, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Yen-Yu Ian Shih
- Department of Neurology, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA UNC Neuroscience Center, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA Biomedical Research Imaging Center, University of North Carolina, Chapel Hill, NC 27599, USA Department of Biomedical Engineering, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Timothy R Gershon
- Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA Department of Neurology, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA UNC Neuroscience Center, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
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23
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Abstract
The development and function of our brain are governed by a genetic blueprint, which reflects dynamic changes over the history of evolution. Recent progress in genetics and genomics, facilitated by next-generation sequencing and single-cell sorting, has identified numerous genomic loci that are associated with a neuroanatomical or neurobehavioral phenotype. Here, we review some of the genetic changes in both protein-coding and noncoding regions that affect brain development and evolution, as well as recent progress in brain transcriptomics. Understanding these genetic changes may provide novel insights into neurological and neuropsychiatric disorders, such as autism and schizophrenia.
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Affiliation(s)
- Byoung-Il Bae
- Division of Genetics and Genomics, Manton Center for Orphan Disease, and Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA; Broad Institute of MIT and Harvard, Boston, MA 02115, USA; and Departments of Pediatrics and Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - Divya Jayaraman
- Division of Genetics and Genomics, Manton Center for Orphan Disease, and Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA; Broad Institute of MIT and Harvard, Boston, MA 02115, USA; and Departments of Pediatrics and Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - Christopher A Walsh
- Division of Genetics and Genomics, Manton Center for Orphan Disease, and Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA; Broad Institute of MIT and Harvard, Boston, MA 02115, USA; and Departments of Pediatrics and Neurology, Harvard Medical School, Boston, MA 02115, USA.
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24
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Pulvers JN, Journiac N, Arai Y, Nardelli J. MCPH1: a window into brain development and evolution. Front Cell Neurosci 2015; 9:92. [PMID: 25870538 PMCID: PMC4376118 DOI: 10.3389/fncel.2015.00092] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 02/28/2015] [Indexed: 12/21/2022] Open
Abstract
The development of the mammalian cerebral cortex involves a series of mechanisms: from patterning, progenitor cell proliferation and differentiation, to neuronal migration. Many factors influence the development of the cerebral cortex to its normal size and neuronal composition. Of these, the mechanisms that influence the proliferation and differentiation of neural progenitor cells are of particular interest, as they may have the greatest consequence on brain size, not only during development but also in evolution. In this context, causative genes of human autosomal recessive primary microcephaly, such as ASPM and MCPH1, are attractive candidates, as many of them show positive selection during primate evolution. MCPH1 causes microcephaly in mice and humans and is involved in a diverse array of molecular functions beyond brain development, including DNA repair and chromosome condensation. Positive selection of MCPH1 in the primate lineage has led to much insight and discussion of its role in brain size evolution. In this review, we will present an overview of MCPH1 from these multiple angles, and whilst its specific role in brain size regulation during development and evolution remain elusive, the pieces of the puzzle will be discussed with the aim of putting together the full picture of this fascinating gene.
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Affiliation(s)
| | - Nathalie Journiac
- U1141 Inserm Paris, France ; Université Paris Diderot, Sorbonne Paris Cité, UMRS 1141 Paris, France
| | - Yoko Arai
- Institut Jacques Monod, CNRS UMR 7592, Université Paris Diderot, Sorbonne Paris Cité Paris, France
| | - Jeannette Nardelli
- U1141 Inserm Paris, France ; Université Paris Diderot, Sorbonne Paris Cité, UMRS 1141 Paris, France
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