1
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Oner M, Chen MC, Cheng PT, Li YH, Cheng YC, Celik A, Soong SW, Hsu LW, Lin DY, Hossain Prince GMS, Dhar T, Cheng HC, Tang PC, Lin H. Impact of metformin on neocortical development during pregnancy: Involvement of ERK and p35/CDK5 pathways. CHEMOSPHERE 2024; 358:142124. [PMID: 38677614 DOI: 10.1016/j.chemosphere.2024.142124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 04/18/2024] [Accepted: 04/21/2024] [Indexed: 04/29/2024]
Abstract
Metformin, the most commonly prescribed drug for the treatment of diabetes, is increasingly used during pregnancy to address various disorders such as diabetes, obesity, preeclampsia, and metabolic diseases. However, its impact on neocortex development remains unclear. Here, we investigated the direct effects of metformin on neocortex development, focusing on ERK and p35/CDK5 regulation. Using a pregnant rat model, we found that metformin treatment during pregnancy induces small for gestational age (SGA) and reduces relative cortical thickness in embryos and neonates. Additionally, we discovered that metformin inhibits neural progenitor cell proliferation in the sub-ventricular zone (SVZ)/ventricular zone (VZ) of the developing neocortex, a process possibly mediated by ERK inactivation. Furthermore, metformin induces neuronal apoptosis in the SVZ/VZ area of the developing neocortex. Moreover, metformin retards neuronal migration, cortical lamination, and differentiation, potentially through p35/CDK5 inhibition in the developing neocortex. Remarkably, compensating for p35 through in utero electroporation partially rescues metformin-impaired neuronal migration and development. In summary, our study reveals that metformin disrupts neocortex development by inhibiting neuronal progenitor proliferation, neuronal migration, cortical layering, and cortical neuron maturation, likely via ERK and p35/CDK5 inhibition. Consequently, our findings advocate for caution in metformin usage during pregnancy, given its potential adverse effects on fetal brain development.
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Affiliation(s)
- Muhammet Oner
- Department of Life Sciences, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Mei-Chih Chen
- Translational Cell Therapy Center, Department of Medical Research, China Medical University Hospital, Taichung, 40447, Taiwan
| | - Pang-Ting Cheng
- Department of Life Sciences, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Yu-Hsuan Li
- Translational Cell Therapy Center, Department of Medical Research, China Medical University Hospital, Taichung, 40447, Taiwan
| | - Yu-Chiao Cheng
- Department of Life Sciences, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Ayse Celik
- Department of Life Sciences, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Shiuan-Woei Soong
- Department of Life Sciences, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Li-Wen Hsu
- Department of Life Sciences, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Din-You Lin
- Department of Life Sciences, National Chung Hsing University, Taichung, 40227, Taiwan
| | | | - Trayee Dhar
- Department of Life Sciences, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Hsu-Chen Cheng
- Department of Life Sciences, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Pin-Chi Tang
- Department of Animal Science, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Ho Lin
- Department of Life Sciences, National Chung Hsing University, Taichung, 40227, Taiwan.
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2
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Galaburda AM. Animal models of developmental dyslexia. Front Neurosci 2022; 16:981801. [DOI: 10.3389/fnins.2022.981801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 10/28/2022] [Indexed: 11/15/2022] Open
Abstract
As some critics have stated, the term “developmental dyslexia” refers to a strictly human disorder, relating to a strictly human capacity – reading – so it cannot be modeled in experimental animals, much less so in lowly rodents. However, two endophenotypes associated with developmental dyslexia are eminently suitable for animal modeling: Cerebral Lateralization, as illustrated by the association between dyslexia and non-righthandedness, and Cerebrocortical Dysfunction, as illustrated by the described abnormal structural anatomy and/or physiology and functional imaging of the dyslexic cerebral cortex. This paper will provide a brief review of these two endophenotypes in human beings with developmental dyslexia and will describe the animal work done in my laboratory and that of others to try to shed light on the etiology of and neural mechanisms underlying developmental dyslexia. Some thought will also be given to future directions of the research.
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3
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Animal models of developmental dyslexia: Where we are and what we are missing. Neurosci Biobehav Rev 2021; 131:1180-1197. [PMID: 34699847 DOI: 10.1016/j.neubiorev.2021.10.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 10/20/2021] [Accepted: 10/22/2021] [Indexed: 12/21/2022]
Abstract
Developmental dyslexia (DD) is a complex neurodevelopmental disorder and the most common learning disability among both school-aged children and across languages. Recently, sensory and cognitive mechanisms have been reported to be potential endophenotypes (EPs) for DD, and nine DD-candidate genes have been identified. Animal models have been used to investigate the etiopathological pathways that underlie the development of complex traits, as they enable the effects of genetic and/or environmental manipulations to be evaluated. Animal research designs have also been linked to cutting-edge clinical research questions by capitalizing on the use of EPs. For the present scoping review, we reviewed previous studies of murine models investigating the effects of DD-candidate genes. Moreover, we highlighted the use of animal models as an innovative way to unravel new insights behind the pathophysiology of reading (dis)ability and to assess cutting-edge preclinical models.
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4
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Landi N, Perdue M. Neuroimaging genetics studies of specific reading disability and developmental language disorder: A review. LANGUAGE AND LINGUISTICS COMPASS 2019; 13:e12349. [PMID: 31844423 PMCID: PMC6913889 DOI: 10.1111/lnc3.12349] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Developmental disorders of spoken and written language are heterogeneous in nature with impairments observed across various linguistic, cognitive, and sensorimotor domains. These disorders are also associated with characteristic patterns of atypical neural structure and function that are observable early in development, often before formal schooling begins. Established patterns of heritability point toward genetic contributions, and molecular genetics approaches have identified genes that play a role in these disorders. Still, identified genes account for only a limited portion of phenotypic variance in complex developmental disorders, described as the problem of "missing heritability." The characterization of intermediate phenotypes at the neural level may fill gaps in our understanding of heritability patterns in complex disorders, and the emerging field of neuroimaging genetics offers a promising approach to accomplish this goal. The neuroimaging genetics approach is gaining prevalence in language- and reading-related research as it is well-suited to incorporate behavior, genetics, and neurobiology into coherent etiological models of complex developmental disorders. Here, we review research applying the neuroimaging genetics approach to the study of specific reading disability (SRD) and developmental language disorder (DLD), much of which links genes with known neurodevelopmental function to functional and structural abnormalities in the brain.
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Affiliation(s)
- Nicole Landi
- Department of Psychological Sciences, University of Connecticut, Storrs, Connecticut, United States; Haskins Laboratories, United States
| | - Meaghan Perdue
- Department of Psychological Sciences, University of Connecticut, Storrs, Connecticut, United States; Haskins Laboratories, United States
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5
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Krafnick AJ, Evans TM. Neurobiological Sex Differences in Developmental Dyslexia. Front Psychol 2019; 9:2669. [PMID: 30687153 PMCID: PMC6336691 DOI: 10.3389/fpsyg.2018.02669] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 12/12/2018] [Indexed: 12/13/2022] Open
Abstract
Understanding sex differences at the neurobiological level has become increasingly crucial in both basic and applied research. In the study of developmental dyslexia, early neuroimaging investigations were dominated by male-only or male-dominated samples, due at least in part to males being diagnosed more frequently. While recent studies more consistently balance the inclusion of both sexes, there has been little movement toward directly characterizing potential sex differences of the disorder. However, a string of recent work suggests that the brain basis of dyslexia may indeed be different in males and females. This potential sex difference has implications for existing models of dyslexia, and would inform approaches to the remediation of reading difficulties. This article reviews recent evidence for sex differences in dyslexia, discusses the impact these studies have on the understanding of the brain basis of dyslexia, and provides a framework for how these differential neuroanatomical profiles may develop.
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Affiliation(s)
- Anthony J Krafnick
- Psychology Department, Dominican University, River Forest, IL, United States
| | - Tanya M Evans
- Center for Advanced Study of Teaching and Learning, Curry School of Education and Human Development, University of Virginia, Charlottesville, VA, United States
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6
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Guidi LG, Velayos‐Baeza A, Martinez‐Garay I, Monaco AP, Paracchini S, Bishop DVM, Molnár Z. The neuronal migration hypothesis of dyslexia: A critical evaluation 30 years on. Eur J Neurosci 2018; 48:3212-3233. [PMID: 30218584 PMCID: PMC6282621 DOI: 10.1111/ejn.14149] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 08/06/2018] [Accepted: 08/13/2018] [Indexed: 12/29/2022]
Abstract
The capacity for language is one of the key features underlying the complexity of human cognition and its evolution. However, little is known about the neurobiological mechanisms that mediate normal or impaired linguistic ability. For developmental dyslexia, early postmortem studies conducted in the 1980s linked the disorder to subtle defects in the migration of neurons in the developing neocortex. These early studies were reinforced by human genetic analyses that identified dyslexia susceptibility genes and subsequent evidence of their involvement in neuronal migration. In this review, we examine recent experimental evidence that does not support the link between dyslexia and neuronal migration. We critically evaluate gene function studies conducted in rodent models and draw attention to the lack of robust evidence from histopathological and imaging studies in humans. Our review suggests that the neuronal migration hypothesis of dyslexia should be reconsidered, and the neurobiological basis of dyslexia should be approached with a fresh start.
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Affiliation(s)
- Luiz G. Guidi
- Department of Physiology, Anatomy, and GeneticsUniversity of OxfordOxfordUK
- Wellcome Centre for Human GeneticsUniversity of OxfordOxfordUK
| | - Antonio Velayos‐Baeza
- Department of Physiology, Anatomy, and GeneticsUniversity of OxfordOxfordUK
- Wellcome Centre for Human GeneticsUniversity of OxfordOxfordUK
| | - Isabel Martinez‐Garay
- Department of Physiology, Anatomy, and GeneticsUniversity of OxfordOxfordUK
- Division of NeuroscienceSchool of BiosciencesCardiff UniversityCardiffUK
| | | | | | | | - Zoltán Molnár
- Department of Physiology, Anatomy, and GeneticsUniversity of OxfordOxfordUK
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Müller B, Boltze J, Czepezauer I, Hesse V, Wilcke A, Kirsten H. Dyslexia risk variant rs600753 is linked with dyslexia-specific differential allelic expression of DYX1C1. Genet Mol Biol 2018; 41:41-49. [PMID: 29473935 PMCID: PMC5901500 DOI: 10.1590/1678-4685-gmb-2017-0165] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 08/28/2017] [Indexed: 11/22/2022] Open
Abstract
An increasing number of genetic variants involved in dyslexia development were
discovered during the last years, yet little is known about the molecular
functional mechanisms of these SNPs. In this study we investigated whether
dyslexia candidate SNPs have a direct, disease-specific effect on local
expression levels of the assumed target gene by using a differential allelic
expression assay. In total, 12 SNPs previously associated with dyslexia and
related phenotypes were suitable for analysis. Transcripts corresponding to four
SNPs were sufficiently expressed in 28 cell lines originating from controls and
a family affected by dyslexia. We observed a significant effect of rs600753 on
expression levels of DYX1C1 in forward and reverse sequencing
approaches. The expression level of the rs600753 risk allele was increased in
the respective seven cell lines from members of the dyslexia family which might
be due to a disturbed transcription factor binding sites. When considering our
results in the context of neuroanatomical dyslexia-specific findings, we
speculate that this mechanism may be part of the pathomechanisms underlying the
dyslexia-specific brain phenotype. Our results suggest that allele-specific
DYX1C1 expression levels depend on genetic variants of
rs600753 and contribute to dyslexia. However, these results are preliminary and
need replication.
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Affiliation(s)
- Bent Müller
- Fraunhofer Institute for Cell Therapy and Immunology, Leipzig, Germany
| | - Johannes Boltze
- Fraunhofer Research Institution for Marine Biotechnology, Department of Medical Cell Technology, Lübeck, Germany.,Institute for Medical and Marine Biotechnology, University of Lübeck, Lübeck, Germany
| | - Ivonne Czepezauer
- Fraunhofer Institute for Cell Therapy and Immunology, Leipzig, Germany
| | - Volker Hesse
- German Center for Growth, Development and Health Encouragement in Childhood and Adolescence, Berlin, Germany.,Charité-University Medicine Berlin, Institute for Experimental Paediatric Endocrinolgy, Berlin
| | | | - Arndt Wilcke
- Fraunhofer Institute for Cell Therapy and Immunology, Leipzig, Germany
| | - Holger Kirsten
- Fraunhofer Institute for Cell Therapy and Immunology, Leipzig, Germany.,Institute for Medical Informatics, Statistics and Epidemiology, University of Leipzig, Leipzig, Germany.,LIFE - Leipzig Research Center for Civilization Diseases, University of Leipzig, Leipzig, Germany
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8
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Waye MMY, Poo LK, Ho CSH. Study of Genetic Association With DCDC2 and Developmental Dyslexia in Hong Kong Chinese Children. Clin Pract Epidemiol Ment Health 2017; 13:104-114. [PMID: 29081827 PMCID: PMC5633722 DOI: 10.2174/1745017901713010104] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 06/21/2017] [Accepted: 07/25/2017] [Indexed: 11/30/2022]
Abstract
Background: Doublecortin domain-containing 2 (DCDC2) is a doublecortin domain-containing gene family member and the doublecortin domain has been demonstrated to bind to tubulin and enhance microtubule polymerization. It has been associated with developmental dyslexia and this protein family member is thought to function in neuronal migration where it may affect the signaling of primary cilia. Objectives: The objective of the study is to find out if there is any association of genetic variants of DCDC2 with developmental dyslexia in Chinese children from Hong Kong. Methods: The dyslexic children were diagnosed as developmental dyslexia (DD) using the Hong Kong Test of Specific Learning Difficulties in Reading and Writing (HKT-SpLD) by the Department of Health, Hong Kong. Saliva specimens were collected and their genotypes of DCDC2 were studied by DNA sequencing or TaqMan Real Time PCR Assays. Results: The most significant marker is rs6940827 which is associated with DD with nominal p-value (0.011). However, this marker did not remain significant after multiple testing corrections and the adjusted p-value from permutation test was 0.1329. Using sliding window haplotype analysis, several haplotypes were found to be nominally associated with DD. The smallest nominal p values was 0.0036 (rs2996452-rs1318700, C-A). However, none of the p values could withstand the multiple testing corrections. Conclusion: Despite early findings that DCDC2 is a strong candidate for developmental dyslexia and that some of the genetic variants have been linked to brain structure and functions, our findings showed that DCDC2 is not strongly associated with dyslexia.
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Affiliation(s)
- Mary M Y Waye
- The Nethersole School of Nursing, The Nethersole School of Nursing, The Chinese University of Hong Kong, Hong Kong
| | - Lim K Poo
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong
| | - Connie S-H Ho
- Department of Psychology, The University of Hong Kong, Hong Kong
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9
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Hancock R, Pugh KR, Hoeft F. Neural Noise Hypothesis of Developmental Dyslexia. Trends Cogn Sci 2017; 21:434-448. [PMID: 28400089 PMCID: PMC5489551 DOI: 10.1016/j.tics.2017.03.008] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 02/27/2017] [Accepted: 03/15/2017] [Indexed: 11/26/2022]
Abstract
Developmental dyslexia (decoding-based reading disorder; RD) is a complex trait with multifactorial origins at the genetic, neural, and cognitive levels. There is evidence that low-level sensory-processing deficits precede and underlie phonological problems, which are one of the best-documented aspects of RD. RD is also associated with impairments in integrating visual symbols with their corresponding speech sounds. Although causal relationships between sensory processing, print-speech integration, and fluent reading, and their neural bases are debated, these processes all require precise timing mechanisms across distributed brain networks. Neural excitability and neural noise are fundamental to these timing mechanisms. Here, we propose that neural noise stemming from increased neural excitability in cortical networks implicated in reading is one key distal contributor to RD.
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Affiliation(s)
- Roeland Hancock
- Department of Psychiatry and Weill Institute for Neurosciences, University of California, San Francisco (UCSF), 401 Parnassus Ave. Box-0984, San Francisco, CA 94143, USA; Science-based Innovation in Learning Center (SILC), 401 Parnassus Ave. Box-0984, San Francisco, CA 94143, USA.
| | - Kenneth R Pugh
- Haskins Laboratories, 300 George Street, New Haven, CT 06511, USA; Department of Linguistics, Yale University, 370 Temple Street, New Haven, CT 06520, USA; Department of Radiology and Biomedical Imaging, Yale University, 330 Cedar Street, New Haven, CT 06520, USA; Department of Psychological Sciences, University of Connecticut, 406 Babbidge Road, Storrs, CT 06269, USA
| | - Fumiko Hoeft
- Department of Psychiatry and Weill Institute for Neurosciences, University of California, San Francisco (UCSF), 401 Parnassus Ave. Box-0984, San Francisco, CA 94143, USA; Haskins Laboratories, 300 George Street, New Haven, CT 06511, USA; Department of Neuropsychiatry, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160, Japan; Science-based Innovation in Learning Center (SILC), 401 Parnassus Ave. Box-0984, San Francisco, CA 94143, USA; Dyslexia Center, UCSF, 675 Nelson Rising Lane, San Francisco, CA 94158, USA.
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10
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Xia Z, Hancock R, Hoeft F. Neurobiological bases of reading disorder Part I: Etiological investigations. LANGUAGE AND LINGUISTICS COMPASS 2017; 11:e12239. [PMID: 28785303 PMCID: PMC5543813 DOI: 10.1111/lnc3.12239] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 03/22/2017] [Indexed: 05/29/2023]
Abstract
While many studies have focused on identifying the neural and behavioral characteristics of decoding-based reading disorder (RD, aka developmental dyslexia), the etiology of RD remains largely unknown and understudied. Because the brain plays an intermediate role between genetic factors and behavioral outcomes, it is promising to address causality from a neural perspective. In the current, Part I of the two-part review, we discuss neuroimaging approaches to addressing the causality issue and review the results of studies that have employed these approaches. We assume that if a neural signature were associated with RD etiology, it would (a) manifest across comparisons in different languages, (b) be experience independent and appear in comparisons between RD and reading-matched controls, (c) be present both pre- and post-intervention, (d) be found in at-risk, pre-reading children and (e) be associated with genetic risk. We discuss each of these five characteristics in turn and summarize the studies that have examined each of them. The available literature provides evidence that anomalies in left temporo-parietal cortex, and possibly occipito-temporal cortex, may be closely related to the etiology of RD. Improved understanding of the etiology of RD can help improve the accuracy of early detection and enable targeted intervention of cognitive processes that are amenable to change, leading to improved outcomes in at-risk or affected populations.
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Affiliation(s)
- Zhichao Xia
- Department of Psychiatry and Weill Institute for Neurosciences, University of California San Francisco, USA
- State Key Laboratory of Cognitive Neuroscience and Learning & IDG/McGovern Institute for Brain Research, Beijing Normal University, China
- Center for Collaboration and Innovation in Brain and Learning Sciences, Beijing Normal University, China
| | - Roeland Hancock
- Department of Psychiatry and Weill Institute for Neurosciences, University of California San Francisco, USA
| | - Fumiko Hoeft
- Department of Psychiatry and Weill Institute for Neurosciences, University of California San Francisco, USA
- Haskins Laboratories, USA
- Department of Neuropsychiatry, Keio University School of Medicine, Japan
- Dyslexia Center, University of California San Francisco, USA
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11
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Trulioff A, Ermakov A, Malashichev Y. Primary Cilia as a Possible Link between Left-Right Asymmetry and Neurodevelopmental Diseases. Genes (Basel) 2017; 8:genes8020048. [PMID: 28125008 PMCID: PMC5333037 DOI: 10.3390/genes8020048] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 12/21/2016] [Accepted: 01/19/2017] [Indexed: 12/11/2022] Open
Abstract
Cilia have multiple functions in the development of the entire organism, and participate in the development and functioning of the central nervous system. In the last decade, studies have shown that they are implicated in the development of the visceral left-right asymmetry in different vertebrates. At the same time, some neuropsychiatric disorders, such as schizophrenia, autism, bipolar disorder, and dyslexia, are known to be associated with lateralization failure. In this review, we consider possible links in the mechanisms of determination of visceral asymmetry and brain lateralization, through cilia. We review the functions of seven genes associated with both cilia, and with neurodevelopmental diseases, keeping in mind their possible role in the establishment of the left-right brain asymmetry.
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Affiliation(s)
- Andrey Trulioff
- Department of Vertebrate Zoology, Faculty of Biology, Saint Petersburg State University, Universitetskaya nab., 7/9, Saint Petersburg 199034, Russia.
| | - Alexander Ermakov
- Department of Vertebrate Zoology, Faculty of Biology, Saint Petersburg State University, Universitetskaya nab., 7/9, Saint Petersburg 199034, Russia.
- Laboratory of Molecular Neurobiology, Department of Ecological Physiology, Institute of Experimental Medicine, ul. Akad. Pavlov, 12, Saint Petersburg 197376, Russia.
| | - Yegor Malashichev
- Department of Vertebrate Zoology, Faculty of Biology, Saint Petersburg State University, Universitetskaya nab., 7/9, Saint Petersburg 199034, Russia.
- Laboratory of Molecular Neurobiology, Department of Ecological Physiology, Institute of Experimental Medicine, ul. Akad. Pavlov, 12, Saint Petersburg 197376, Russia.
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12
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Neurogenetics of developmental dyslexia: from genes to behavior through brain neuroimaging and cognitive and sensorial mechanisms. Transl Psychiatry 2017; 7:e987. [PMID: 28045463 PMCID: PMC5545717 DOI: 10.1038/tp.2016.240] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Accepted: 10/15/2016] [Indexed: 01/18/2023] Open
Abstract
Developmental dyslexia (DD) is a complex neurodevelopmental deficit characterized by impaired reading acquisition, in spite of adequate neurological and sensorial conditions, educational opportunities and normal intelligence. Despite the successful characterization of DD-susceptibility genes, we are far from understanding the molecular etiological pathways underlying the development of reading (dis)ability. By focusing mainly on clinical phenotypes, the molecular genetics approach has yielded mixed results. More optimally reduced measures of functioning, that is, intermediate phenotypes (IPs), represent a target for researching disease-associated genetic variants and for elucidating the underlying mechanisms. Imaging data provide a viable IP for complex neurobehavioral disorders and have been extensively used to investigate both morphological, structural and functional brain abnormalities in DD. Performing joint genetic and neuroimaging studies in humans is an emerging strategy to link DD-candidate genes to the brain structure and function. A limited number of studies has already pursued the imaging-genetics integration in DD. However, the results are still not sufficient to unravel the complexity of the reading circuit due to heterogeneous study design and data processing. Here, we propose an interdisciplinary, multilevel, imaging-genetic approach to disentangle the pathways from genes to behavior. As the presence of putative functional genetic variants has been provided and as genetic associations with specific cognitive/sensorial mechanisms have been reported, new hypothesis-driven imaging-genetic studies must gain momentum. This approach would lead to the optimization of diagnostic criteria and to the early identification of 'biologically at-risk' children, supporting the definition of adequate and well-timed prevention strategies and the implementation of novel, specific remediation approach.
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13
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Kong R, Song RR. [Research advances in susceptible genes for developmental dyslexia in children]. ZHONGGUO DANG DAI ER KE ZA ZHI = CHINESE JOURNAL OF CONTEMPORARY PEDIATRICS 2016; 18:1308-1312. [PMID: 27974128 PMCID: PMC7403085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 07/03/2016] [Accepted: 08/24/2016] [Indexed: 12/16/2023]
Abstract
Developmental dyslexia in children is one of the neurodevelopmental disorders and is affected by various susceptible genes. In recent years, researchers have found some susceptible genes for dyslexia via chromosome analysis, genome-wide association studies, association analysis, gene function research, neuroimaging, and neurophysiological techniques. This article reviews the research advances in susceptible genes for developmental dyslexia, and with the study on susceptible genes for dyslexia, it lays a foundation for in-depth studies on the "gene-brain-behavior" level and provides scientific clues for exploring etiology and pathogenesis of dyslexia.
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Affiliation(s)
- Rui Kong
- Department of Maternal and Child Health Care, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
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14
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Kong R, Song RR. [Research advances in susceptible genes for developmental dyslexia in children]. ZHONGGUO DANG DAI ER KE ZA ZHI = CHINESE JOURNAL OF CONTEMPORARY PEDIATRICS 2016; 18:1308-1312. [PMID: 27974128 PMCID: PMC7403085 DOI: 10.7499/j.issn.1008-8830.2016.12.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 07/03/2016] [Accepted: 08/24/2016] [Indexed: 06/06/2023]
Abstract
Developmental dyslexia in children is one of the neurodevelopmental disorders and is affected by various susceptible genes. In recent years, researchers have found some susceptible genes for dyslexia via chromosome analysis, genome-wide association studies, association analysis, gene function research, neuroimaging, and neurophysiological techniques. This article reviews the research advances in susceptible genes for developmental dyslexia, and with the study on susceptible genes for dyslexia, it lays a foundation for in-depth studies on the "gene-brain-behavior" level and provides scientific clues for exploring etiology and pathogenesis of dyslexia.
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Affiliation(s)
- Rui Kong
- Department of Maternal and Child Health Care, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
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15
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An assessment of gene-by-gene interactions as a tool to unfold missing heritability in dyslexia. Hum Genet 2015; 134:749-60. [DOI: 10.1007/s00439-015-1555-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Accepted: 04/12/2015] [Indexed: 12/24/2022]
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16
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Centanni TM, Chen F, Booker AM, Engineer CT, Sloan AM, Rennaker RL, LoTurco JJ, Kilgard MP. Speech sound processing deficits and training-induced neural plasticity in rats with dyslexia gene knockdown. PLoS One 2014; 9:e98439. [PMID: 24871331 PMCID: PMC4037188 DOI: 10.1371/journal.pone.0098439] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2013] [Accepted: 05/02/2014] [Indexed: 11/18/2022] Open
Abstract
In utero RNAi of the dyslexia-associated gene Kiaa0319 in rats (KIA-) degrades cortical responses to speech sounds and increases trial-by-trial variability in onset latency. We tested the hypothesis that KIA- rats would be impaired at speech sound discrimination. KIA- rats needed twice as much training in quiet conditions to perform at control levels and remained impaired at several speech tasks. Focused training using truncated speech sounds was able to normalize speech discrimination in quiet and background noise conditions. Training also normalized trial-by-trial neural variability and temporal phase locking. Cortical activity from speech trained KIA- rats was sufficient to accurately discriminate between similar consonant sounds. These results provide the first direct evidence that assumed reduced expression of the dyslexia-associated gene KIAA0319 can cause phoneme processing impairments similar to those seen in dyslexia and that intensive behavioral therapy can eliminate these impairments.
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Affiliation(s)
- Tracy M. Centanni
- School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, Texas, United States of America
| | - Fuyi Chen
- Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, United States of America
| | - Anne M. Booker
- Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, United States of America
| | - Crystal T. Engineer
- School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, Texas, United States of America
| | - Andrew M. Sloan
- School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, Texas, United States of America
| | - Robert L. Rennaker
- School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, Texas, United States of America
| | - Joseph J. LoTurco
- Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, United States of America
| | - Michael P. Kilgard
- School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, Texas, United States of America
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17
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Reading and language disorders: the importance of both quantity and quality. Genes (Basel) 2014; 5:285-309. [PMID: 24705331 PMCID: PMC4094934 DOI: 10.3390/genes5020285] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Revised: 03/11/2014] [Accepted: 03/12/2014] [Indexed: 01/25/2023] Open
Abstract
Reading and language disorders are common childhood conditions that often co-occur with each other and with other neurodevelopmental impairments. There is strong evidence that disorders, such as dyslexia and Specific Language Impairment (SLI), have a genetic basis, but we expect the contributing genetic factors to be complex in nature. To date, only a few genes have been implicated in these traits. Their functional characterization has provided novel insight into the biology of neurodevelopmental disorders. However, the lack of biological markers and clear diagnostic criteria have prevented the collection of the large sample sizes required for well-powered genome-wide screens. One of the main challenges of the field will be to combine careful clinical assessment with high throughput genetic technologies within multidisciplinary collaborations.
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Mascheretti S, Riva V, Giorda R, Beri S, Lanzoni LFE, Cellino MR, Marino C. KIAA0319 and ROBO1: evidence on association with reading and pleiotropic effects on language and mathematics abilities in developmental dyslexia. J Hum Genet 2014; 59:189-97. [PMID: 24430574 DOI: 10.1038/jhg.2013.141] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Revised: 12/13/2013] [Accepted: 12/22/2013] [Indexed: 01/17/2023]
Abstract
Substantial heritability has been reported for developmental dyslexia (DD), and KIAA0319 and ROBO1 appear as more than plausible candidate susceptibility genes for this developmental disorder. Converging evidence indicates that developmental difficulties in oral language and mathematics can predate or co-occur with DD, and substantial genetic correlations have been found between these abilities and reading traits. In this study, we explored the role of eight single-nucleotide polymorphisms spanning within KIAA0319 and ROBO1 genes, and DD as a dichotomic trait, related neuropsychological phenotypes and comorbid language and mathematical (dis)abilities in a large cohort of 493 Italian nuclear families ascertained through a proband with a diagnosis of DD. Marker-trait association was analyzed by implementing a general test of family-based association for quantitative traits (that is, the Quantitative Transmission Disequilibrium Test, version 2.5.1). By providing evidence for significant association with mathematics skills, our data add further result in support of ROBO1 contributing to the deficits in DD and its correlated phenotypes. Taken together, our findings shed further light into the etiologic basis and the phenotypic complexity of this developmental disorder.
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Affiliation(s)
- Sara Mascheretti
- Child Psychopathology Unit, Scientific Institute, IRCCS Eugenio Medea, Bosisio Parini, Lecco, Italy
| | - Valentina Riva
- Child Psychopathology Unit, Scientific Institute, IRCCS Eugenio Medea, Bosisio Parini, Lecco, Italy
| | - Roberto Giorda
- Molecular Biology Lab, Scientific Institute, IRCCS Eugenio Medea, Bosisio Parini, Lecco, Italy
| | - Silvana Beri
- Molecular Biology Lab, Scientific Institute, IRCCS Eugenio Medea, Bosisio Parini, Lecco, Italy
| | | | - Maria Rosaria Cellino
- Centro Regionale di Riferimento per i Disturbi dell'Apprendimento-CRRDA, ULSS 20, Verona, Italy
| | - Cecilia Marino
- 1] Centre de recherche de l'Institut universitaire en santé mentale de Québec, Québec, QC, Canada [2] Département de Psychiatrie et Neurosciences, Faculté de Médecine, Université Laval, Québec, QC, Canada
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19
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Eicher JD, Gruen JR. Imaging-genetics in dyslexia: connecting risk genetic variants to brain neuroimaging and ultimately to reading impairments. Mol Genet Metab 2013; 110:201-12. [PMID: 23916419 PMCID: PMC3800223 DOI: 10.1016/j.ymgme.2013.07.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Revised: 07/02/2013] [Accepted: 07/02/2013] [Indexed: 12/19/2022]
Abstract
Dyslexia is a common pediatric disorder that affects 5-17% of schoolchildren in the United States. It is marked by unexpected difficulties in fluent reading despite adequate intelligence, opportunity, and instruction. Classically, neuropsychologists have studied dyslexia using a variety of neurocognitive batteries to gain insight into the specific deficits and impairments in affected children. Since dyslexia is a complex genetic trait with high heritability, analyses conditioned on performance on these neurocognitive batteries have been used to try to identify associated genes. This has led to some successes in identifying contributing genes, although much of the heritability remains unexplained. Additionally, the lack of relevant human brain tissue for analysis and the challenges of modeling a uniquely human trait in animals are barriers to advancing our knowledge of the underlying pathophysiology. In vivo imaging technologies, however, present new opportunities to examine dyslexia and reading skills in a clearly relevant context in human subjects. Recent investigations have started to integrate these imaging data with genetic data in attempts to gain a more complete and complex understanding of reading processes. In addition to bridging the gap from genetic risk variant to a discernible neuroimaging phenotype and ultimately to the clinical impairments in reading performance, the use of neuroimaging phenotypes will reveal novel risk genes and variants. In this article, we briefly discuss the genetic and imaging investigations and take an in-depth look at the recent imaging-genetics investigations of dyslexia.
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Affiliation(s)
- John D. Eicher
- Department of Genetics, Yale University School of Medicine, New Haven, CT 06520
| | - Jeffrey R. Gruen
- Department of Genetics, Yale University School of Medicine, New Haven, CT 06520
- Departments of Pediatrics and Investigative Medicine, Yale University School of Medicine, New Haven, CT 06520
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20
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Carrion-Castillo A, Franke B, Fisher SE. Molecular genetics of dyslexia: an overview. DYSLEXIA (CHICHESTER, ENGLAND) 2013; 19:214-240. [PMID: 24133036 DOI: 10.1002/dys.1464] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Accepted: 09/02/2013] [Indexed: 05/28/2023]
Abstract
Dyslexia is a highly heritable learning disorder with a complex underlying genetic architecture. Over the past decade, researchers have pinpointed a number of candidate genes that may contribute to dyslexia susceptibility. Here, we provide an overview of the state of the art, describing how studies have moved from mapping potential risk loci, through identification of associated gene variants, to characterization of gene function in cellular and animal model systems. Work thus far has highlighted some intriguing mechanistic pathways, such as neuronal migration, axon guidance, and ciliary biology, but it is clear that we still have much to learn about the molecular networks that are involved. We end the review by highlighting the past, present, and future contributions of the Dutch Dyslexia Programme to studies of genetic factors. In particular, we emphasize the importance of relating genetic information to intermediate neurobiological measures, as well as the value of incorporating longitudinal and developmental data into molecular designs.
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Affiliation(s)
- Amaia Carrion-Castillo
- Language and Genetics Department, Max Planck Institute for Psycholinguistics, Nijmegen, Netherlands
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21
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Platt MP, Adler WT, Mehlhorn AJ, Johnson GC, Wright KA, Choi RT, Tsang WH, Poon MW, Yeung SY, Waye MMY, Galaburda AM, Rosen GD. Embryonic disruption of the candidate dyslexia susceptibility gene homolog Kiaa0319-like results in neuronal migration disorders. Neuroscience 2013; 248:585-93. [PMID: 23831424 DOI: 10.1016/j.neuroscience.2013.06.056] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 06/19/2013] [Accepted: 06/20/2013] [Indexed: 02/04/2023]
Abstract
Developmental dyslexia, the most common childhood learning disorder, is highly heritable, and recent studies have identified KIAA0319-Like (KIAA0319L) as a candidate dyslexia susceptibility gene at the 1p36-34 (DYX8) locus. In this experiment, we investigated the anatomical effects of knocking down this gene during rat corticogenesis. Cortical progenitor cells were transfected using in utero electroporation on embryonic day (E) 15.5 with plasmids encoding either: (1) Kiaa0319l small hairpin RNA (shRNA), (2) an expression construct for human KIAA0319L, (3) Kiaa0319l shRNA+KIAA0319L expression construct (rescue), or (4) controls (scrambled Kiaa0319l shRNA or empty expression vector). Mothers were injected with 5-bromo-2-deoxyuridine (BrdU) at either E13.5, E15.5, or E17.5. Disruption of Kiaa0319l function (by knockdown, overexpression, or rescue) resulted in the formation of large nodular periventricular heterotopia in approximately 25% of the rats, which can be seen as early as postnatal day 1. Only a small subset of heterotopic neurons had been transfected, indicating non-cell autonomous effects of the transfection. Most heterotopic neurons were generated in mid- to late-gestation, and laminar markers suggest that they were destined for upper cortical laminae. Finally, we found that transfected neurons in the cerebral cortex were located in their expected laminae. These results indicate that KIAA0319L is the fourth of four candidate dyslexia susceptibility genes that is involved in neuronal migration, which supports the association of abnormal neuronal migration with developmental dyslexia.
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Affiliation(s)
- M P Platt
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA, USA
| | - W T Adler
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA, USA
| | - A J Mehlhorn
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA, USA
| | - G C Johnson
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA, USA
| | - K A Wright
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA, USA
| | - R T Choi
- School of Biomedical Sciences & School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - W H Tsang
- School of Biomedical Sciences & School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - M W Poon
- School of Biomedical Sciences & School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - S Y Yeung
- School of Biomedical Sciences & School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - M M Y Waye
- School of Biomedical Sciences & School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - A M Galaburda
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA, USA
| | - G D Rosen
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA, USA.
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22
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Adler WT, Platt MP, Mehlhorn AJ, Haight JL, Currier TA, Etchegaray MA, Galaburda AM, Rosen GD. Position of neocortical neurons transfected at different gestational ages with shRNA targeted against candidate dyslexia susceptibility genes. PLoS One 2013; 8:e65179. [PMID: 23724130 PMCID: PMC3665803 DOI: 10.1371/journal.pone.0065179] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 04/24/2013] [Indexed: 01/12/2023] Open
Abstract
Developmental dyslexia is a language learning disorder that affects approximately 4–10% of the population. A number of candidate dyslexia susceptibility genes have been identified, including DCDC2 and KIAA0319 on Chromosome (Chr) 6p22.2 and DYX1C1 on Chr 15q21. Embryonic knockdown of the function of homologs of these genes in rat neocortical projection cell progenitors by in utero electroporation of plasmids encoding small hairpin RNA (shRNA) revealed that all three genes disrupted neuronal migration to the neocortex. Specifically, this disruption would result in heterotopia formation (Dyx1c1 and Kiaa0319) and/or overmigration past their expected laminar location (Dyx1c1 and Dcdc2). In these experiments, neurons normally destined for the upper neocortical laminæ were transfected on embryonic day (E) 15.5, and we designed experiments to test whether these migration phenotypes were the result of targeting a specific type of projection neuron. We transfected litters with Dcdc2 shRNA, Dyx1c1 shRNA, Kiaa0319 shRNA, or fluorescent protein (as a control) at each of three gestational ages (E14.5, E15.5, or E16.5). Pups were allowed to come to term, and their brains were examined at 3 weeks of age for the position of transfected cells. We found that age of transfection did not affect the percentage of unmigrated neurons—transfection with Kiaa0319 shRNA resulted in heterotopia formation at all three ages. Overmigration of neurons transfected with Dcdc2 shRNA, while present following transfections at the later ages, did not occur following E14.5 transfections. These results are considered in light of the known functions of each of these candidate dyslexia susceptibility genes.
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Affiliation(s)
- William T. Adler
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States of America
| | - Maryann P. Platt
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States of America
| | - Alison J. Mehlhorn
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States of America
| | - Joshua L. Haight
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States of America
| | - Timothy A. Currier
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States of America
| | - Mikel A. Etchegaray
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States of America
| | - Albert M. Galaburda
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States of America
| | - Glenn D. Rosen
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States of America
- * E-mail:
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23
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Szalkowski CE, Booker AB, Truong DT, Threlkeld SW, Rosen GD, Fitch RH. Knockdown of the candidate dyslexia susceptibility gene homolog dyx1c1 in rodents: effects on auditory processing, visual attention, and cortical and thalamic anatomy. Dev Neurosci 2013; 35:50-68. [PMID: 23594585 DOI: 10.1159/000348431] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Accepted: 01/23/2013] [Indexed: 12/24/2022] Open
Abstract
The current study investigated the behavioral and neuroanatomical effects of embryonic knockdown of the candidate dyslexia susceptibility gene (CDSG) homolog Dyx1c1 through RNA interference (RNAi) in rats. Specifically, we examined long-term effects on visual attention abilities in male rats, in addition to assessing rapid and complex auditory processing abilities in male and, for the first time, female rats. Our results replicated prior evidence of complex acoustic processing deficits in Dyx1c1 male rats and revealed new evidence of comparable deficits in Dyx1c1 female rats. Moreover, we found new evidence that knocking down Dyx1c1 produced orthogonal impairments in visual attention in the male subgroup. Stereological analyses of male brains from prior RNAi studies revealed that, despite consistent visible evidence of disruptions of neuronal migration (i.e., heterotopia), knockdown of Dyx1c1 did not significantly alter the cortical volume, hippocampal volume, or midsagittal area of the corpus callosum (measured in a separate cohort of like-treated Dyx1c1 male rats). Dyx1c1 transfection did, however, lead to significant changes in medial geniculate nucleus (MGN) anatomy, with a significant shift to smaller MGN neurons in Dyx1c1-transfected animals. Combined results provide important information about the impact of Dyx1c1 on behavioral functions that parallel domains known to be affected in language-impaired populations as well as information about widespread changes to the brain following early disruption of this CDSG.
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Affiliation(s)
- Caitlin E Szalkowski
- Department of Psychology/Behavioral Neuroscience, University of Connecticut, Storrs, Conn. 06269, USA.
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24
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Tammimies K, Vitezic M, Matsson H, Le Guyader S, Bürglin TR, Ohman T, Strömblad S, Daub CO, Nyman TA, Kere J, Tapia-Páez I. Molecular networks of DYX1C1 gene show connection to neuronal migration genes and cytoskeletal proteins. Biol Psychiatry 2013; 73:583-90. [PMID: 23036959 DOI: 10.1016/j.biopsych.2012.08.012] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2012] [Revised: 08/07/2012] [Accepted: 08/08/2012] [Indexed: 11/28/2022]
Abstract
BACKGROUND The dyslexia susceptibility 1 candidate 1 (DYX1C1) gene has recently been associated with dyslexia and reading scores in several population samples. The DYX1C1 has also been shown to affect neuronal migration and modulate estrogen receptor signaling. METHODS We have analyzed the molecular networks of DYX1C1 by gene expression and protein interaction profiling in a human neuroblastoma cell line. RESULTS We find that DYX1C1 can modulate the expression of nervous system development and neuronal migration genes such as RELN and associate with a number of cytoskeletal proteins. We also show by live cell imaging that DYX1C1 regulates cell migration of the human neuroblastoma cell line dependent on its tetratricopeptide repeat and DYX1 protein domains. The DYX1 domain is a novel highly conserved domain identified in this study by multiple sequence alignment of DYX1C1 proteins recovered from a wide range of eukaryotic species. CONCLUSIONS Our results contribute to the hypothesis that dyslexia has a developmental neurobiological basis by linking DYX1C1 with many genes involved in neuronal migration disorders.
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Affiliation(s)
- Kristiina Tammimies
- Center for Biosciences, Department of Biosciences and Nutrition, Novum, Karolinska Institutet, Huddinge, Sweden
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25
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Xq27 FRAXA locus is a strong candidate for dyslexia: evidence from a genome-wide scan in French families. Behav Genet 2013; 43:132-40. [PMID: 23307483 DOI: 10.1007/s10519-012-9575-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Accepted: 12/08/2012] [Indexed: 12/11/2022]
Abstract
Dyslexia is a frequent neurodevelopmental learning disorder. To date, nine susceptibility loci have been identified, one of them being DYX9, located in Xq27. We performed the first French SNP linkage study followed by candidate gene investigation in dyslexia by studying 12 multiplex families (58 subjects) with at least two children affected, according to categorical restrictive criteria for phenotype definition. Significant results emerged on Xq27.3 within DYX9. The maximum multipoint LOD score reached 3,884 between rs12558359 and rs454992. Within this region, seven candidate genes were investigated for mutations in exonic sequences (CXORF1, CXORF51, SLITRK2, FMR1, FMR2, ASFMR1, FMR1NB), all having a role during brain development. We further looked for 5'UTR trinucleotide repeats in FMR1 and FMR2 genes. No mutation or polymorphism co-segregating with dyslexia was found. This finding in French families with Dyslexia showed significant linkage on Xq27.3 enclosing FRAXA, and consequently confirmed the DYX9 region as a robust susceptibility locus. We reduced the previously described interval from 6.8 (DXS1227-DXS8091) to 4 Mb also disclosing a higher LOD score.
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26
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Raskind WH, Peter B, Richards T, Eckert MM, Berninger VW. The genetics of reading disabilities: from phenotypes to candidate genes. Front Psychol 2013; 3:601. [PMID: 23308072 PMCID: PMC3538356 DOI: 10.3389/fpsyg.2012.00601] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Accepted: 12/18/2012] [Indexed: 12/19/2022] Open
Abstract
This article provides an overview of (a) issues in definition and diagnosis of specific reading disabilities at the behavioral level that may occur in different constellations of developmental and phenotypic profiles (patterns); (b) rapidly expanding research on genetic heterogeneity and gene candidates for dyslexia and other reading disabilities; (c) emerging research on gene-brain relationships; and (d) current understanding of epigenetic mechanisms whereby environmental events may alter behavioral expression of genetic variations. A glossary of genetic terms (denoted by bold font) is provided for readers not familiar with the technical terms.
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Affiliation(s)
- Wendy H Raskind
- Department of Medicine, University of Washington Seattle, WA, USA ; Department of Psychiatry and Behavioral Sciences, University of Washington Seattle, WA, USA
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27
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Wang X, Sun QQ. Characterization of axo-axonic synapses in the piriform cortex of Mus musculus. J Comp Neurol 2012; 520:832-47. [PMID: 22020781 DOI: 10.1002/cne.22792] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Previous anatomical and physiological studies have established major glutamatergic and GABAergic neuronal subtypes within the piriform cortical circuits. However, quantitative information regarding axo-axonic inhibitory synapses mediated by chandelier cells across major cortical subdivisions of piriform cortex is lacking. Therefore, we examined the properties of these synapses across the entire piriform cortex. Our results show the following. 1) γ-Aminobutyric acid membrane transporter 1-positive varicosities, whose appearance resembles chandelier cartridges, are found around the initial segments of axons of glutamatergic cells across layers II and III. 2) Both the density of axo-axonic cartridges and the degree of γ-aminobutyric acid membrane transporter 1 innervation in each axo-axonic synapse are significantly higher in the piriform cortex than in the neocortex. 3) Glutamate decarboxylase 67, vesicular GABA transporter, and parvalbumin, but not calbindin, are colocalized with the presynaptic varicosities, whereas gephyrin, Na-K-2Cl cotransporter 1, and GABA(A) receptor α1 subunit, but not K-Cl cotransporter 2, are colocalized at the presumed postsynaptic sites. 4) The axo-axonic cartridges innervate the majority of excitatory neurons and are distributed more frequently in putative centrifugal cells and posterior piriform cortex. We further describe the morphology of chandelier cells by using parvalbumin-immunoreactivity and single-cell labeling. In summary, our results demonstrate that a small population of chandelier cells mediates abundant axo-axonic synapses across the entire piriform cortex. Because of the critical location of these inhibitory synapses in relation to action potential regulation, our results highlight a critical role of axo-axonic synapses in regulating information flow and olfactory-related oscillations within the piriform cortex in vivo.
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Affiliation(s)
- Xinjun Wang
- Department of Zoology and Physiology, University of Wyoming, Laramie, Wyoming 82071, USA
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