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Schijven D, Soheili-Nezhad S, Fisher SE, Francks C. Exome-wide analysis implicates rare protein-altering variants in human handedness. Nat Commun 2024; 15:2632. [PMID: 38565598 PMCID: PMC10987538 DOI: 10.1038/s41467-024-46277-w] [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: 07/21/2023] [Accepted: 02/20/2024] [Indexed: 04/04/2024] Open
Abstract
Handedness is a manifestation of brain hemispheric specialization. Left-handedness occurs at increased rates in neurodevelopmental disorders. Genome-wide association studies have identified common genetic effects on handedness or brain asymmetry, which mostly involve variants outside protein-coding regions and may affect gene expression. Implicated genes include several that encode tubulins (microtubule components) or microtubule-associated proteins. Here we examine whether left-handedness is also influenced by rare coding variants (frequencies ≤ 1%), using exome data from 38,043 left-handed and 313,271 right-handed individuals from the UK Biobank. The beta-tubulin gene TUBB4B shows exome-wide significant association, with a rate of rare coding variants 2.7 times higher in left-handers than right-handers. The TUBB4B variants are mostly heterozygous missense changes, but include two frameshifts found only in left-handers. Other TUBB4B variants have been linked to sensorineural and/or ciliopathic disorders, but not the variants found here. Among genes previously implicated in autism or schizophrenia by exome screening, DSCAM and FOXP1 show evidence for rare coding variant association with left-handedness. The exome-wide heritability of left-handedness due to rare coding variants was 0.91%. This study reveals a role for rare, protein-altering variants in left-handedness, providing further evidence for the involvement of microtubules and disorder-relevant genes.
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Affiliation(s)
- Dick Schijven
- Language & Genetics Department, Max Planck Institute for Psycholinguistics, Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands
| | - Sourena Soheili-Nezhad
- Language & Genetics Department, Max Planck Institute for Psycholinguistics, Nijmegen, The Netherlands
| | - Simon E Fisher
- Language & Genetics Department, Max Planck Institute for Psycholinguistics, Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands
| | - Clyde Francks
- Language & Genetics Department, Max Planck Institute for Psycholinguistics, Nijmegen, The Netherlands.
- Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands.
- Department of Cognitive Neuroscience, Radboud University Medical Center, Nijmegen, The Netherlands.
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2
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Luo D, Ottesen E, Lee JH, Singh R. Transcriptome- and proteome-wide effects of a circular RNA encompassing four early exons of the spinal muscular atrophy genes. RESEARCH SQUARE 2024:rs.3.rs-3818622. [PMID: 38464174 PMCID: PMC10925445 DOI: 10.21203/rs.3.rs-3818622/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Spinal muscular atrophy (SMA) genes, SMN1 and SMN2, produce multiple circular RNAs (circRNAs), including C2A-2B-3-4 that encompasses early exons 2A, 2B, 3 and 4. Here we report the transcriptome- and proteome-wide effects of overexpression of C2A-2B-3-4 in inducible HEK293 cells. Our RNA-Seq analysis revealed altered expression of ~ 15% genes (4,172 genes) by C2A-2B-3-4. About half of the affected genes by C2A-2B-3-4 remained unaffected by L2A-2B-3-4, a linear transcript encompassing exons 2A, 2B, 3 and 4 of SMN1/SMN2. These fifindings underscore the unique role of the structural context of C2A-2B-3-4 in gene regulation. A surprisingly high number of upregulated genes by C2A-2B-3-4 were located on chromosomes 4 and 7, whereas many of the downregulated genes were located on chromosomes 10 and X. Supporting a cross-regulation of SMN1/SMN2 transcripts, C2A-2B-3-4 and L2A-2B-3-4 upregulated and downregulated SMN1/SMN2 mRNAs, respectively. Proteome analysis revealed 61 upregulated and 57 downregulated proteins by C2A-2B-3-4 with very limited overlap with those affected by L2A-2B-3-4. Independent validations confirmed the effect of C2A-2B-3-4 on expression of genes associated with chromatin remodeling, transcription, spliceosome function, ribosome biogenesis, lipid metabolism, cytoskeletal formation, cell proliferation and neuromuscular junction formation. Our findings reveal a broad role of C2A-2B-3-4, a universally expressed circRNA produced by SMN1/SMN2.
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3
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Costa FV, Zabegalov KN, Kolesnikova TO, de Abreu MS, Kotova MM, Petersen EV, Kalueff AV. Experimental models of human cortical malformations: from mammals to 'acortical' zebrafish. Neurosci Biobehav Rev 2023; 155:105429. [PMID: 37863278 DOI: 10.1016/j.neubiorev.2023.105429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Revised: 10/05/2023] [Accepted: 10/16/2023] [Indexed: 10/22/2023]
Abstract
Human neocortex controls and integrates cognition, emotions, perception and complex behaviors. Aberrant cortical development can be triggered by multiple genetic and environmental factors, causing cortical malformations. Animal models, especially rodents, are a valuable tool to probe molecular and physiological mechanisms of cortical malformations. Complementing rodent studies, the zebrafish (Danio rerio) is an important model organism in biomedicine. Although the zebrafish (like other fishes) lacks neocortex, here we argue that this species can still be used to model various aspects and brain phenomena related to human cortical malformations. We also discuss novel perspectives in this field, covering both advantages and limitations of using mammalian and zebrafish models in cortical malformation research. Summarizing mounting evidence, we also highlight the importance of translationally-relevant insights into the pathogenesis of cortical malformations from animal models, and discuss future strategies of research in the field.
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Affiliation(s)
- Fabiano V Costa
- World-class Research Center "Center for Personalized Medicine", Almazov National Medical Research Center, Ministry of Healthcare of Russian Federation, St. Petersburg, Russia; Neurobiology Program, Sirius University of Science and Technology, Sirius Federal Territory, Russia
| | - Konstantin N Zabegalov
- Neurobiology Program, Sirius University of Science and Technology, Sirius Federal Territory, Russia
| | - Tatiana O Kolesnikova
- World-class Research Center "Center for Personalized Medicine", Almazov National Medical Research Center, Ministry of Healthcare of Russian Federation, St. Petersburg, Russia; Neurobiology Program, Sirius University of Science and Technology, Sirius Federal Territory, Russia
| | | | - Maria M Kotova
- World-class Research Center "Center for Personalized Medicine", Almazov National Medical Research Center, Ministry of Healthcare of Russian Federation, St. Petersburg, Russia; Neurobiology Program, Sirius University of Science and Technology, Sirius Federal Territory, Russia
| | | | - Allan V Kalueff
- World-class Research Center "Center for Personalized Medicine", Almazov National Medical Research Center, Ministry of Healthcare of Russian Federation, St. Petersburg, Russia; Institute of Translational Biomedicine, St. Petersburg State University, St. Petersburg, Russia; Institute of Experimental Medicine, Almazov National Medical Research Centre, Ministry of Healthcare of Russian Federation, St. Petersburg, Russia; Laboratory of Preclinical Bioscreening, Granov Russian Research Center of Radiology and Surgical Technologies, Ministry of Healthcare of Russian Federation, Pesochny, Russia; Ural Federal University, Yekaterinburg, Russia; Neurobiology Program, Sirius University of Science and Technology, Sirius Federal Territory, Russia.
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4
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McKenna ED, Sarbanes SL, Cummings SW, Roll-Mecak A. The Tubulin Code, from Molecules to Health and Disease. Annu Rev Cell Dev Biol 2023; 39:331-361. [PMID: 37843925 DOI: 10.1146/annurev-cellbio-030123-032748] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2023]
Abstract
Microtubules are essential dynamic polymers composed of α/β-tubulin heterodimers. They support intracellular trafficking, cell division, cellular motility, and other essential cellular processes. In many species, both α-tubulin and β-tubulin are encoded by multiple genes with distinct expression profiles and functionality. Microtubules are further diversified through abundant posttranslational modifications, which are added and removed by a suite of enzymes to form complex, stereotyped cellular arrays. The genetic and chemical diversity of tubulin constitute a tubulin code that regulates intrinsic microtubule properties and is read by cellular effectors, such as molecular motors and microtubule-associated proteins, to provide spatial and temporal specificity to microtubules in cells. In this review, we synthesize the rapidly expanding tubulin code literature and highlight limitations and opportunities for the field. As complex microtubule arrays underlie essential physiological processes, a better understanding of how cells employ the tubulin code has important implications for human disease ranging from cancer to neurological disorders.
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Affiliation(s)
- Elizabeth D McKenna
- Cell Biology and Biophysics Unit, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, Bethesda, Maryland, USA;
| | - Stephanie L Sarbanes
- Cell Biology and Biophysics Unit, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, Bethesda, Maryland, USA;
| | - Steven W Cummings
- Cell Biology and Biophysics Unit, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, Bethesda, Maryland, USA;
| | - Antonina Roll-Mecak
- Cell Biology and Biophysics Unit, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, Bethesda, Maryland, USA;
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, Bethesda, Maryland, USA
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5
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Zhang L, Tie X, Che F, Wang G, Ge Y, Li B, Yang Y. Novel maternal duplication of 6p22.3-p25.3 with subtelomeric 6p25.3 deletion: new clinical findings and genotype-phenotype correlations. Mol Cytogenet 2023; 16:11. [PMID: 37303060 DOI: 10.1186/s13039-023-00640-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Accepted: 05/24/2023] [Indexed: 06/13/2023] Open
Abstract
BACKGROUND Copy-number variants (CNVs) drive many neurodevelopmental-related disorders. Although many neurodevelopmental-related CNVs can give rise to widespread phenotypes, it is necessary to identify the major genes contributing to phenotypic presentation. Copy-number variations in chromosome 6, such as independent 6p deletion and 6p duplication, have been reported in several live-born infants and present widespread abnormalities such as intellectual disability, growth deficiency, developmental delay, and multiple dysmorphic facial features. However, a contiguous deletion and duplication in chromosome 6p regions have been reported in only a few cases. CASE PRESENTATION In this study, we reported the first duplication of chromosome band 6p25.3-p22.3 with deletion of 6p25.3 in a pedigree. This is the first case reported involving CNVs in these chromosomal regions. In this pedigree, we reported a 1-year-old boy with maternal 6p25-pter duplication characterized by chromosome karyotype. Further analysis using CNV-seq revealed a 20.88-Mb duplication at 6p25.3-p22.3 associated with a contiguous 0.66-Mb 6p25.3 deletion. Whole exome sequencing confirmed the deletion/duplication and identified no pathogenic or likely pathogenic variants related with the patient´s phenotype. The proband presented abnormal growth, developmental delay, skeletal dysplasia, hearing loss, and dysmorphic facial features. Additionally, he presented recurrent infection after birth. CNV-seq using the proband´s parental samples showed that the deletion/duplication was inherited from the proband´s mother, who exhibited a similar phenotype to the proband. When compared with other cases, this proband and his mother presented a new clinical finding: forearm bone dysplasia. The major candidate genes contributing to recurrent infection, eye development, hearing loss features, neurodevelopmental development, and congenital bone dysplasia were further discussed. CONCLUSIONS Our results showed a new clinical finding of a contiguous deletion and duplication in chromosome 6p regions and suggested candidate genes associated with phenotypic features, such as FOXC1, SERPINB6, NRN1, TUBB2A, IRF4, and RIPK1.
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Affiliation(s)
- Liyu Zhang
- Shaanxi Institute for Pediatric Diseases, Xi'an Children's Hospital, Xi'an, China
| | - Xiaoling Tie
- Department of Rehabilitation, Xi'an Children's Hospital, Xi'an, China
| | - Fengyu Che
- Shaanxi Institute for Pediatric Diseases, Xi'an Children's Hospital, Xi'an, China
| | - Guoxia Wang
- Shaanxi Institute for Pediatric Diseases, Xi'an Children's Hospital, Xi'an, China
| | - Ying Ge
- The Center Laboratory Medicine, Xi'an Children's Hospital, Xi'an, China
| | - Benchang Li
- Shaanxi Institute for Pediatric Diseases, Xi'an Children's Hospital, Xi'an, China
| | - Ying Yang
- Shaanxi Institute for Pediatric Diseases, Xi'an Children's Hospital, Xi'an, China.
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6
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Atkins M, Nicol X, Fassier C. Microtubule remodelling as a driving force of axon guidance and pruning. Semin Cell Dev Biol 2023; 140:35-53. [PMID: 35710759 DOI: 10.1016/j.semcdb.2022.05.030] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 04/26/2022] [Accepted: 05/31/2022] [Indexed: 01/28/2023]
Abstract
The establishment of neuronal connectivity relies on the microtubule (MT) cytoskeleton, which provides mechanical support, roads for axonal transport and mediates signalling events. Fine-tuned spatiotemporal regulation of MT functions by tubulin post-translational modifications and MT-associated proteins is critical for the coarse wiring and subsequent refinement of neuronal connectivity. The defective regulation of these processes causes a wide range of neurodevelopmental disorders associated with connectivity defects. This review focuses on recent studies unravelling how MT composition, post-translational modifications and associated proteins influence MT functions in axon guidance and/or pruning to build functional neuronal circuits. We here summarise experimental evidence supporting the key role of this network as a driving force for growth cone steering and branch-specific axon elimination. We further provide a global overview of the MT-interactors that tune developing axon behaviours, with a special emphasis on their emerging versatility in the regulation of MT dynamics/structure. Recent studies establishing the key and highly selective role of the tubulin code in the regulation of MT functions in axon pathfinding are also reported. Finally, our review highlights the emerging molecular links between these MT regulation processes and guidance signals that wire the nervous system.
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Affiliation(s)
- Melody Atkins
- INSERM, UMR-S 1270, Institut du Fer à Moulin, Sorbonne Université, F-75005 Paris, France
| | - Xavier Nicol
- Institut de la Vision, Sorbonne Université, INSERM, CNRS, F-75012 Paris, France
| | - Coralie Fassier
- Institut de la Vision, Sorbonne Université, INSERM, CNRS, F-75012 Paris, France.
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7
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Jin A, Xu H, Gao X, Sun S, Yang Y, Huang X, Wang X, Liu Y, Zhu Y, Dai Q, Bian Q, Jiang L. ScRNA-Seq Reveals a Distinct Osteogenic Progenitor of Alveolar Bone. J Dent Res 2023; 102:645-655. [PMID: 37148259 DOI: 10.1177/00220345231159821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2023] Open
Abstract
The metabolism and remodeling of alveolar bone are the most active among the whole skeletal system, which is related to the biological characteristics and heterogeneity of the bone mesenchymal stromal cells (MSCs). However, there is a lack of systematic description of the heterogeneity of MSC-derived osteoblastic lineage cells as well as their distinct osteogenic differentiation trajectory of alveolar bone. In this study, we constructed a single-cell atlas of the mouse alveolar bone cells through single-cell RNA sequencing (scRNA-seq). Remarkably, by comparing the cell compositions between the alveolar bone and long bone, we uncovered a previously undescribed cell population that exhibits a high expression of protocadherin Fat4 (Fat4+ cells) and is specifically enriched around alveolar bone marrow cavities. ScRNA-seq analysis indicated that Fat4+ cells may initiate a distinct osteogenic differentiation trajectory in the alveolar bone. By isolating and cultivating Fat4+ cells in vitro, we demonstrated that they possess colony-forming, osteogenic, and adipogenic capabilities. Moreover, FAT4 knockdown could significantly inhibit the osteogenic differentiation of alveolar bone MSCs. Furthermore, we revealed that the Fat4+ cells exhibit a core transcriptional signature consisting of several key transcription factors, such as SOX6, which are involved in osteogenesis, and further demonstrated that SOX6 is required for the efficient osteogenic differentiation of the Fat4+ cells. Collectively, our high-resolution single-cell atlas of the alveolar bone reveals a distinct osteogenic progenitor that may contribute to the unique physiological characteristics of alveolar bone.
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Affiliation(s)
- A Jin
- Center of Craniofacial Orthodontics, Department of Oral and Cranio-maxillofacial Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- College of Stomatology, Shanghai Jiao Tong University, Shanghai, China
- National Center for Stomatology, Shanghai, China
- National Clinical Research Center for Oral Diseases, Shanghai, China
- Shanghai Key Laboratory of Stomatology, Shanghai, China
| | - H Xu
- Center of Craniofacial Orthodontics, Department of Oral and Cranio-maxillofacial Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- College of Stomatology, Shanghai Jiao Tong University, Shanghai, China
- National Center for Stomatology, Shanghai, China
- National Clinical Research Center for Oral Diseases, Shanghai, China
- Shanghai Key Laboratory of Stomatology, Shanghai, China
| | - X Gao
- Center of Craniofacial Orthodontics, Department of Oral and Cranio-maxillofacial Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- College of Stomatology, Shanghai Jiao Tong University, Shanghai, China
- National Center for Stomatology, Shanghai, China
- National Clinical Research Center for Oral Diseases, Shanghai, China
- Shanghai Key Laboratory of Stomatology, Shanghai, China
| | - S Sun
- Center of Craniofacial Orthodontics, Department of Oral and Cranio-maxillofacial Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- College of Stomatology, Shanghai Jiao Tong University, Shanghai, China
- National Center for Stomatology, Shanghai, China
- National Clinical Research Center for Oral Diseases, Shanghai, China
- Shanghai Key Laboratory of Stomatology, Shanghai, China
| | - Y Yang
- Center of Craniofacial Orthodontics, Department of Oral and Cranio-maxillofacial Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- College of Stomatology, Shanghai Jiao Tong University, Shanghai, China
- National Center for Stomatology, Shanghai, China
- National Clinical Research Center for Oral Diseases, Shanghai, China
- Shanghai Key Laboratory of Stomatology, Shanghai, China
| | - X Huang
- Center of Craniofacial Orthodontics, Department of Oral and Cranio-maxillofacial Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- College of Stomatology, Shanghai Jiao Tong University, Shanghai, China
- National Center for Stomatology, Shanghai, China
- National Clinical Research Center for Oral Diseases, Shanghai, China
- Shanghai Key Laboratory of Stomatology, Shanghai, China
| | - X Wang
- Center of Craniofacial Orthodontics, Department of Oral and Cranio-maxillofacial Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- College of Stomatology, Shanghai Jiao Tong University, Shanghai, China
- National Center for Stomatology, Shanghai, China
- National Clinical Research Center for Oral Diseases, Shanghai, China
- Shanghai Key Laboratory of Stomatology, Shanghai, China
| | - Y Liu
- Center of Craniofacial Orthodontics, Department of Oral and Cranio-maxillofacial Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- College of Stomatology, Shanghai Jiao Tong University, Shanghai, China
- National Center for Stomatology, Shanghai, China
- National Clinical Research Center for Oral Diseases, Shanghai, China
- Shanghai Key Laboratory of Stomatology, Shanghai, China
| | - Y Zhu
- Center of Craniofacial Orthodontics, Department of Oral and Cranio-maxillofacial Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- College of Stomatology, Shanghai Jiao Tong University, Shanghai, China
- National Center for Stomatology, Shanghai, China
- National Clinical Research Center for Oral Diseases, Shanghai, China
- Shanghai Key Laboratory of Stomatology, Shanghai, China
| | - Q Dai
- College of Stomatology, Shanghai Jiao Tong University, Shanghai, China
- National Center for Stomatology, Shanghai, China
- National Clinical Research Center for Oral Diseases, Shanghai, China
- Shanghai Key Laboratory of Stomatology, Shanghai, China
- The 2nd Dental Center, Ninth People's Hospital, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Q Bian
- Center of Craniofacial Orthodontics, Department of Oral and Cranio-maxillofacial Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- College of Stomatology, Shanghai Jiao Tong University, Shanghai, China
- National Center for Stomatology, Shanghai, China
- National Clinical Research Center for Oral Diseases, Shanghai, China
- Shanghai Key Laboratory of Stomatology, Shanghai, China
- Shanghai Institute of Precision Medicine, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - L Jiang
- Center of Craniofacial Orthodontics, Department of Oral and Cranio-maxillofacial Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- College of Stomatology, Shanghai Jiao Tong University, Shanghai, China
- National Center for Stomatology, Shanghai, China
- National Clinical Research Center for Oral Diseases, Shanghai, China
- Shanghai Key Laboratory of Stomatology, Shanghai, China
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Muto V, Benigni F, Magliocca V, Borghi R, Flex E, Pallottini V, Rosa A, Compagnucci C, Tartaglia M. CRISPR/Cas9 and piggyBac Transposon-Based Conversion of a Pathogenic Biallelic TBCD Variant in a Patient-Derived iPSC Line Allows Correction of PEBAT-Related Endophenotypes. Int J Mol Sci 2023; 24:ijms24097988. [PMID: 37175696 PMCID: PMC10178052 DOI: 10.3390/ijms24097988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 04/20/2023] [Accepted: 04/21/2023] [Indexed: 05/15/2023] Open
Abstract
Induced pluripotent stem cells (iPSCs) have been established as a reliable in vitro disease model system and represent a particularly informative tool when animal models are not available or do not recapitulate the human pathophenotype. The recognized limit in using this technology is linked to some degree of variability in the behavior of the individual patient-derived clones. The development of CRISPR/Cas9-based gene editing solves this drawback by obtaining isogenic iPSCs in which the genetic lesion is corrected, allowing a straightforward comparison with the parental patient-derived iPSC lines. Here, we report the generation of a footprint-free isogenic cell line of patient-derived TBCD-mutated iPSCs edited using the CRISPR/Cas9 and piggyBac technologies. The corrected iPSC line had no genetic footprint after the removal of the selection cassette and maintained its "stemness". The correction of the disease-causing TBCD missense substitution restored proper protein levels of the chaperone and mitotic spindle organization, as well as reduced cellular death, which were used as read-outs of the TBCD KO-related endophenotype. The generated line represents an informative in vitro model to understand the impact of pathogenic TBCD mutations on nervous system development and physiology.
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Affiliation(s)
- Valentina Muto
- Molecular Genetics and Functional Genomics, Ospedale Pediatrico Bambino Gesù, IRCCS, 00146 Rome, Italy
| | - Federica Benigni
- Molecular Genetics and Functional Genomics, Ospedale Pediatrico Bambino Gesù, IRCCS, 00146 Rome, Italy
- Department of Science, University Roma Tre, 00146 Rome, Italy
| | - Valentina Magliocca
- Molecular Genetics and Functional Genomics, Ospedale Pediatrico Bambino Gesù, IRCCS, 00146 Rome, Italy
| | - Rossella Borghi
- Molecular Genetics and Functional Genomics, Ospedale Pediatrico Bambino Gesù, IRCCS, 00146 Rome, Italy
| | - Elisabetta Flex
- Department of Oncology and Molecular Medicine, Istituto Superiore di Sanità, 00161 Rome, Italy
| | - Valentina Pallottini
- Department of Science, University Roma Tre, 00146 Rome, Italy
- Neuroendocrinology Metabolism and Neuropharmacology Unit, IRCSS Fondazione Santa Lucia, 00143 Rome, Italy
| | - Alessandro Rosa
- Department of Biology and Biotechnologies "Charles Darwin", Sapienza University of Rome, 00185 Rome, Italy
- Center for Life Nano- & Neuro-Science, Fondazione Istituto Italiano di Tecnologia (IIT), 00161 Rome, Italy
| | - Claudia Compagnucci
- Molecular Genetics and Functional Genomics, Ospedale Pediatrico Bambino Gesù, IRCCS, 00146 Rome, Italy
| | - Marco Tartaglia
- Molecular Genetics and Functional Genomics, Ospedale Pediatrico Bambino Gesù, IRCCS, 00146 Rome, Italy
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9
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Rraku E, Kerstjens-Frederikse WS, Swertz MA, Dijkhuizen T, van Ravenswaaij-Arts CMA, Engwerda A. The phenotypic spectrum of terminal and subterminal 6p deletions based on a social media-derived cohort and literature review. Orphanet J Rare Dis 2023; 18:68. [PMID: 36964621 PMCID: PMC10039519 DOI: 10.1186/s13023-023-02670-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 03/11/2023] [Indexed: 03/26/2023] Open
Abstract
BACKGROUND Terminal 6p deletions are rare, and information on their clinical consequences is scarce, which impedes optimal management and follow-up by clinicians. The parent-driven Chromosome 6 Project collaborates with families of affected children worldwide to better understand the clinical effects of chromosome 6 aberrations and to support clinical guidance. A microarray report is required for participation, and detailed phenotype information is collected directly from parents through a multilingual web-based questionnaire. Information collected from parents is then combined with case data from literature reports. Here, we present our findings on 13 newly identified patients and 46 literature cases with genotypically well-characterised terminal and subterminal 6p deletions. We provide phenotype descriptions for both the whole group and for subgroups based on deletion size and HI gene content. RESULTS The total group shared a common phenotype characterised by ocular anterior segment dysgenesis, vision problems, brain malformations, congenital defects of the cardiac septa and valves, mild to moderate hearing impairment, eye movement abnormalities, hypotonia, mild developmental delay and dysmorphic features. These characteristics were observed in all subgroups where FOXC1 was included in the deletion, confirming a dominant role for this gene. Additional characteristics were seen in individuals with terminal deletions exceeding 4.02 Mb, namely complex heart defects, corpus callosum abnormalities, kidney abnormalities and orofacial clefting. Some of these additional features may be related to the loss of other genes in the terminal 6p region, such as RREB1 for the cardiac phenotypes and TUBB2A and TUBB2B for the cerebral phenotypes. In the newly identified patients, we observed previously unreported features including gastrointestinal problems, neurological abnormalities, balance problems and sleep disturbances. CONCLUSIONS We present an overview of the phenotypic characteristics observed in terminal and subterminal 6p deletions. This reveals a common phenotype that can be highly attributable to haploinsufficiency of FOXC1, with a possible additional effect of other genes in the 6p25 region. We also delineate the developmental abilities of affected individuals and report on previously unrecognised features, showing the added benefit of collecting information directly from parents. Based on our overview, we provide recommendations for clinical surveillance to support clinicians, patients and families.
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Affiliation(s)
- Eleana Rraku
- Department of Genetics, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands
| | | | - Morris A Swertz
- Department of Genetics, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands
| | - Trijnie Dijkhuizen
- Department of Genetics, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands
| | - Conny M A van Ravenswaaij-Arts
- Department of Genetics, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands.
- ATN/Jonx, Groningen, The Netherlands.
| | - Aafke Engwerda
- Department of Genetics, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands
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10
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Tantry MSA, Santhakumar K. Insights on the Role of α- and β-Tubulin Isotypes in Early Brain Development. Mol Neurobiol 2023; 60:3803-3823. [PMID: 36943622 DOI: 10.1007/s12035-023-03302-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 03/05/2023] [Indexed: 03/23/2023]
Abstract
Tubulins are the highly conserved subunit of microtubules which involve in various fundamental functions including brain development. Microtubules help in neuronal proliferation, migration, differentiation, cargo transport along the axons, synapse formation, and many more. Tubulin gene family consisting of multiple isotypes, their differential expression and varied post translational modifications create a whole new level of complexity and diversity in accomplishing manifold neuronal functions. The studies on the relation between tubulin genes and brain development opened a new avenue to understand the role of each tubulin isotype in neurodevelopment. Mutations in tubulin genes are reported to cause brain development defects especially cortical malformations, referred as tubulinopathies. There is an increased need to understand the molecular correlation between various tubulin mutations and the associated brain pathology. Recently, mutations in tubulin isotypes (TUBA1A, TUBB, TUBB1, TUBB2A, TUBB2B, TUBB3, and TUBG1) have been linked to cause various neurodevelopmental defects like lissencephaly, microcephaly, cortical dysplasia, polymicrogyria, schizencephaly, subcortical band heterotopia, periventricular heterotopia, corpus callosum agenesis, and cerebellar hypoplasia. This review summarizes on the microtubule dynamics, their role in neurodevelopment, tubulin isotypes, post translational modifications, and the role of tubulin mutations in causing specific neurodevelopmental defects. A comprehensive list containing all the reported tubulin pathogenic variants associated with brain developmental defects has been prepared to give a bird's eye view on the broad range of tubulin functions.
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Affiliation(s)
- M S Ananthakrishna Tantry
- Department of Genetic Engineering, SRM Institute of Science and Technology, Kattankulathur, 603203, India
| | - Kirankumar Santhakumar
- Department of Genetic Engineering, SRM Institute of Science and Technology, Kattankulathur, 603203, India.
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11
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Zocchi R, Compagnucci C, Bertini E, Sferra A. Deciphering the Tubulin Language: Molecular Determinants and Readout Mechanisms of the Tubulin Code in Neurons. Int J Mol Sci 2023; 24:ijms24032781. [PMID: 36769099 PMCID: PMC9917122 DOI: 10.3390/ijms24032781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2022] [Revised: 01/17/2023] [Accepted: 01/27/2023] [Indexed: 02/04/2023] Open
Abstract
Microtubules (MTs) are dynamic components of the cell cytoskeleton involved in several cellular functions, such as structural support, migration and intracellular trafficking. Despite their high similarity, MTs have functional heterogeneity that is generated by the incorporation into the MT lattice of different tubulin gene products and by their post-translational modifications (PTMs). Such regulations, besides modulating the tubulin composition of MTs, create on their surface a "biochemical code" that is translated, through the action of protein effectors, into specific MT-based functions. This code, known as "tubulin code", plays an important role in neuronal cells, whose highly specialized morphologies and activities depend on the correct functioning of the MT cytoskeleton and on its interplay with a myriad of MT-interacting proteins. In recent years, a growing number of mutations in genes encoding for tubulins, MT-interacting proteins and enzymes that post-translationally modify MTs, which are the main players of the tubulin code, have been linked to neurodegenerative processes or abnormalities in neural migration, differentiation and connectivity. Nevertheless, the exact molecular mechanisms through which the cell writes and, downstream, MT-interacting proteins decipher the tubulin code are still largely uncharted. The purpose of this review is to describe the molecular determinants and the readout mechanisms of the tubulin code, and briefly elucidate how they coordinate MT behavior during critical neuronal events, such as neuron migration, maturation and axonal transport.
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Affiliation(s)
- Riccardo Zocchi
- Unit of Neuromuscular Disorders, Translational Pediatrics and Clinical Genetics, Bambino Gesù Children’s Hospital, IRCCS, 00146 Rome, Italy
| | - Claudia Compagnucci
- Molecular Genetics and Functional Genomics, Bambino Gesù Children’s Research Hospital, IRCCS, 00146 Rome, Italy
| | - Enrico Bertini
- Unit of Neuromuscular Disorders, Translational Pediatrics and Clinical Genetics, Bambino Gesù Children’s Hospital, IRCCS, 00146 Rome, Italy
- Correspondence: (E.B.); or (A.S.); Tel.: +39-06-6859-2104 (E.B. & A.S.)
| | - Antonella Sferra
- Unit of Neuromuscular Disorders, Translational Pediatrics and Clinical Genetics, Bambino Gesù Children’s Hospital, IRCCS, 00146 Rome, Italy
- Correspondence: (E.B.); or (A.S.); Tel.: +39-06-6859-2104 (E.B. & A.S.)
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12
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Cushion TD, Leca I, Keays DA. MAPping tubulin mutations. Front Cell Dev Biol 2023; 11:1136699. [PMID: 36875768 PMCID: PMC9975266 DOI: 10.3389/fcell.2023.1136699] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Accepted: 02/02/2023] [Indexed: 02/17/2023] Open
Abstract
Microtubules are filamentous structures that play a critical role in a diverse array of cellular functions including, mitosis, nuclear translocation, trafficking of organelles and cell shape. They are composed of α/β-tubulin heterodimers which are encoded by a large multigene family that has been implicated in an umbrella of disease states collectively known as the tubulinopathies. De novo mutations in different tubulin genes are known to cause lissencephaly, microcephaly, polymicrogyria, motor neuron disease, and female infertility. The diverse clinical features associated with these maladies have been attributed to the expression pattern of individual tubulin genes, as well as their distinct Functional repertoire. Recent studies, however, have highlighted the impact of tubulin mutations on microtubule-associated proteins (MAPs). MAPs can be classified according to their effect on microtubules and include polymer stabilizers (e.g., tau, MAP2, doublecortin), destabilizers (e.g., spastin, katanin), plus-end binding proteins (e.g., EB1-3, XMAP215, CLASPs) and motor proteins (e.g., dyneins, kinesins). In this review we analyse mutation-specific disease mechanisms that influence MAP binding and their phenotypic consequences, and discuss methods by which we can exploit genetic variation to identify novel MAPs.
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Affiliation(s)
- Thomas D Cushion
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom.,Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria
| | - Ines Leca
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria
| | - David A Keays
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom.,Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria.,Division of Neurobiology, Department Biology II, Ludwig-Maximilians-University Munich, Munich, Germany
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13
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Attard TJ, Welburn JPI, Marsh JA. Understanding molecular mechanisms and predicting phenotypic effects of pathogenic tubulin mutations. PLoS Comput Biol 2022; 18:e1010611. [PMID: 36206299 PMCID: PMC9581425 DOI: 10.1371/journal.pcbi.1010611] [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: 06/20/2022] [Revised: 10/19/2022] [Accepted: 09/28/2022] [Indexed: 11/21/2022] Open
Abstract
Cells rely heavily on microtubules for several processes, including cell division and molecular trafficking. Mutations in the different tubulin-α and -β proteins that comprise microtubules have been associated with various diseases and are often dominant, sporadic and congenital. While the earliest reported tubulin mutations affect neurodevelopment, mutations are also associated with other disorders such as bleeding disorders and infertility. We performed a systematic survey of tubulin mutations across all isotypes in order to improve our understanding of how they cause disease, and increase our ability to predict their phenotypic effects. Both protein structural analyses and computational variant effect predictors were very limited in their utility for differentiating between pathogenic and benign mutations. This was even worse for those genes associated with non-neurodevelopmental disorders. We selected tubulin-α and -β disease mutations that were most poorly predicted for experimental characterisation. These mutants co-localise to the mitotic spindle in HeLa cells, suggesting they may exert dominant-negative effects by altering microtubule properties. Our results show that tubulin mutations represent a blind spot for current computational approaches, being much more poorly predicted than mutations in most human disease genes. We suggest that this is likely due to their strong association with dominant-negative and gain-of-function mechanisms.
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Affiliation(s)
- Thomas J. Attard
- Wellcome Trust Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, Scotland, United Kingdom
| | - Julie P. I. Welburn
- Wellcome Trust Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, Scotland, United Kingdom
| | - Joseph A. Marsh
- MRC Human Genetics Unit, Institute of Genetics & Cancer, University of Edinburgh, Edinburgh, United Kingdom
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14
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Triantopoulou N, Vidaki M. Local mRNA translation and cytoskeletal reorganization: Mechanisms that tune neuronal responses. Front Mol Neurosci 2022; 15:949096. [PMID: 35979146 PMCID: PMC9376447 DOI: 10.3389/fnmol.2022.949096] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 07/07/2022] [Indexed: 12/31/2022] Open
Abstract
Neurons are highly polarized cells with significantly long axonal and dendritic extensions that can reach distances up to hundreds of centimeters away from the cell bodies in higher vertebrates. Their successful formation, maintenance, and proper function highly depend on the coordination of intricate molecular networks that allow axons and dendrites to quickly process information, and respond to a continuous and diverse cascade of environmental stimuli, often without enough time for communication with the soma. Two seemingly unrelated processes, essential for these rapid responses, and thus neuronal homeostasis and plasticity, are local mRNA translation and cytoskeletal reorganization. The axonal cytoskeleton is characterized by high stability and great plasticity; two contradictory attributes that emerge from the powerful cytoskeletal rearrangement dynamics. Cytoskeletal reorganization is crucial during nervous system development and in adulthood, ensuring the establishment of proper neuronal shape and polarity, as well as regulating intracellular transport and synaptic functions. Local mRNA translation is another mechanism with a well-established role in the developing and adult nervous system. It is pivotal for axonal guidance and arborization, synaptic formation, and function and seems to be a key player in processes activated after neuronal damage. Perturbations in the regulatory pathways of local translation and cytoskeletal reorganization contribute to various pathologies with diverse clinical manifestations, ranging from intellectual disabilities (ID) to autism spectrum disorders (ASD) and schizophrenia (SCZ). Despite the fact that both processes are essential for the orchestration of pathways critical for proper axonal and dendritic function, the interplay between them remains elusive. Here we review our current knowledge on the molecular mechanisms and specific interaction networks that regulate and potentially coordinate these interconnected processes.
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Affiliation(s)
- Nikoletta Triantopoulou
- Division of Basic Sciences, Medical School, University of Crete, Heraklion, Greece
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology Hellas (IMBB-FORTH), Heraklion, Greece
| | - Marina Vidaki
- Division of Basic Sciences, Medical School, University of Crete, Heraklion, Greece
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology Hellas (IMBB-FORTH), Heraklion, Greece
- *Correspondence: Marina Vidaki,
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15
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Maillard C, Roux CJ, Charbit-Henrion F, Steffann J, Laquerriere A, Quazza F, Buisson NB. Tubulin mutations in human neurodevelopmental disorders. Semin Cell Dev Biol 2022; 137:87-95. [PMID: 35915025 DOI: 10.1016/j.semcdb.2022.07.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 07/22/2022] [Accepted: 07/22/2022] [Indexed: 10/16/2022]
Abstract
Mutations causing dysfunction of tubulins and microtubule-associated proteins, also known as tubulinopathies, are a group of recently described entities that lead to complex brain malformations. Anatomical and functional consequences of the disruption of tubulins include microcephaly, combined with abnormal corticogenesis due to impaired migration or lamination and abnormal growth cone dynamics of projecting and callosal axons. Key imaging features of tubulinopathies are characterized by three major patterns of malformations of cortical development (MCD): lissencephaly, microlissencephaly, and dysgyria. Additional distinctive MRI features include dysmorphism of the basal ganglia, midline commissural structure hypoplasia or agenesis, and cerebellar and brainstem hypoplasia. Tubulinopathies can be diagnosed as early as 21-24 gestational weeks using imaging and neuropathology, with possible extreme microlissencephaly with an extremely thin cortex, lissencephaly with either thick or thin/intermediate cortex, and dysgyria combined with cerebellar hypoplasia, pons hypoplasia and corpus callosum dysgenesis. More than 100 MCD-associated mutations have been reported in TUBA1A, TUBB2B, or TUBB3 genes, whereas fewer than ten are known in other genes such TUBB2A, TUBB or TUBG1. Although these mutations are scattered along the α- and β-tubulin sequences, recurrent mutations are consistently associated with almost identical cortical dysgenesis. Much of the evidence supports that these mutations alter the dynamic properties and functions of microtubules in several fashions. These include diminishing the abundance of functional tubulin heterodimers, altering GTP binding, altering longitudinal and lateral protofilament interactions, and impairing microtubule interactions with kinesin and/or dynein motors or with MAPs. In this review we discuss the recent advances in our understanding of the effects of mutations of tubulins and microtubule-associated proteins on human brain development and the pathogenesis of malformations of cortical development.
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Affiliation(s)
- Camille Maillard
- Université de Paris, Imagine Institute, Team Genetics and Development of the Cerebral Cortex, F-75015 Paris, France; Université de Paris, Institute of Psychiatry and Neuroscience of Paris, INSERM U1266, F-75014 Paris, France
| | - Charles Joris Roux
- Pediatric Radiology, Necker Enfants Malades University Hospital, Université de Paris, Paris, France
| | - Fabienne Charbit-Henrion
- Université de Paris, Sorbonne Paris Cité, Imagine INSERM UMR1163, Service de Génétique Moléculaire, Groupe hospitalier Necker-Enfants Malades, AP-HP, France
| | - Julie Steffann
- Université de Paris, Sorbonne Paris Cité, Imagine INSERM UMR1163, Service de Génétique Moléculaire, Groupe hospitalier Necker-Enfants Malades, AP-HP, France
| | - Annie Laquerriere
- Pathology Laboratory, Rouen University Hospital, Rouen, France; NeoVasc Region-Inserm Team ERI28, Laboratory of Microvascular Endothelium and Neonate Brain Lesions, Institute of Research for Innovation in Biomedicine, University of Rouen, Rouen, France
| | - Floriane Quazza
- Pediatric Neurology, Necker Enfants Malades University Hospital, Université de Paris, Paris, France
| | - Nadia Bahi Buisson
- Université de Paris, Imagine Institute, Team Genetics and Development of the Cerebral Cortex, F-75015 Paris, France; Université de Paris, Institute of Psychiatry and Neuroscience of Paris, INSERM U1266, F-75014 Paris, France; Pediatric Neurology, Necker Enfants Malades University Hospital, Université de Paris, Paris, France.
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16
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Tubulinopathy Presenting as Developmental and Epileptic Encephalopathy. CHILDREN 2022; 9:children9081105. [PMID: 35892608 PMCID: PMC9332459 DOI: 10.3390/children9081105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 07/16/2022] [Accepted: 07/19/2022] [Indexed: 11/20/2022]
Abstract
Tubulin proteins play a role in the cortical development. Mutations in the tubulin genes affect patients with brain malformations. The present report describes two cases of developmental and epileptic encephalopathy (DEE) due to tubulinopathy. Case 1, a 23-year-old boy, was found to have a brain malformation with moderate ventriculomegaly prenatally. Hypotonia was noted at birth. Seizures were noted on the 1st day with multifocal discharges on the EEGs, which became intractable to many anticonvulsants. Brain MRI showed marked dilated ventricles and pachy/polymicrogyri. He became a victim of DEE. A de novo mutation in TUBB2B was proven through next-generation sequencing (NGS). Case 2, a mature male baby, began to have myoclonic jerks of his limbs 4 h after birth. EEG showed focal sharp waves from central and temporal regions. Brain MRI showed lissencephaly, type I. The seizures were refractory initially. A de novo mutation in TUBA1A was proven at the 6th week through NGS. He showed the picture of DEE at 1 year and 2 months of age. The clinical features of the tubulinopathies include motor delay, intellectual disabilities, epilepsy, and other deficits. Our cases demonstrated the severe form of tubulinopathy due to major tubulin gene mutations. NGS makes the early identification of genetic etiology possible for clinical evaluation.
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17
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Mitchell CW, Czajewski I, van Aalten DM. Bioinformatic prediction of putative conveyers of O-GlcNAc transferase intellectual disability. J Biol Chem 2022; 298:102276. [PMID: 35863433 PMCID: PMC9428853 DOI: 10.1016/j.jbc.2022.102276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 07/12/2022] [Accepted: 07/14/2022] [Indexed: 02/09/2023] Open
Abstract
Protein O-GlcNAcylation is a dynamic posttranslational modification that is catalyzed by the enzyme O-GlcNAc transferase (OGT) and is essential for neurodevelopment and postnatal neuronal function. Missense mutations in OGT segregate with a novel X-linked intellectual disability syndrome, the OGT congenital disorder of glycosylation (OGT-CDG). One hypothesis for the etiology of OGT-CDG is that loss of OGT activity leads to hypo-O-GlcNAcylation of as yet unidentified, specific neuronal proteins, affecting essential embryonic, and postnatal neurodevelopmental processes; however, the identity of these O-GlcNAcylated proteins is not known. Here, we used bioinformatic techniques to integrate sequence conservation, structural data, clinical data, and the available literature to identify 22 candidate proteins that convey OGT-CDG. We found using gene ontology and PANTHER database data that these candidate proteins are involved in diverse processes including Ras/MAPK signaling, translational repression, cytoskeletal dynamics, and chromatin remodeling. We also identify pathogenic missense variants at O-GlcNAcylation sites that segregate with intellectual disability. This work establishes a preliminary platform for the mechanistic dissection of the links between protein O-GlcNAcylation and neurodevelopment in OGT-CDG.
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Affiliation(s)
- Conor W. Mitchell
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark,Division of Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Ignacy Czajewski
- Division of Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Daan M.F. van Aalten
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark,Division of Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee, United Kingdom,For correspondence: Daan M. F. van Aalten
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18
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Abstract
The microtubule cytoskeleton is assembled from the α- and β-tubulin subunits of the canonical tubulin heterodimer, which polymerizes into microtubules, and a small number of other family members, such as γ-tubulin, with specialized functions. Overall, microtubule function involves the collective action of multiple α- and β-tubulin isotypes. However, despite 40 years of awareness that most eukaryotes harbor multiple tubulin isotypes, their role in the microtubule cytoskeleton has remained relatively unclear. Various model organisms offer specific advantages for gaining insight into the role of tubulin isotypes. Whereas simple unicellular organisms such as yeast provide experimental tractability that can facilitate deeper access to mechanistic details, more complex organisms, such as the fruit fly, nematode and mouse, can be used to discern potential specialized functions of tissue- and structure-specific isotypes. Here, we review the role of α- and β-tubulin isotypes in microtubule function and in associated tubulinopathies with an emphasis on the advances gained using model organisms. Overall, we argue that studying tubulin isotypes in a range of organisms can reveal the fundamental mechanisms by which they mediate microtubule function. It will also provide valuable perspectives on how these mechanisms underlie the functional and biological diversity of the cytoskeleton.
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Affiliation(s)
- Emmanuel T Nsamba
- Genetics, Development, and Cell Biology, Iowa State University, Ames, IA 50011, USA
| | - Mohan L Gupta
- Genetics, Development, and Cell Biology, Iowa State University, Ames, IA 50011, USA
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19
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Krajka V, Vulinovic F, Genova M, Tanzer K, Jijumon AS, Bodakuntla S, Tennstedt S, Mueller-Fielitz H, Meier B, Janke C, Klein C, Rakovic A. H-ABC- and dystonia-causing TUBB4A mutations show distinct pathogenic effects. SCIENCE ADVANCES 2022; 8:eabj9229. [PMID: 35275727 PMCID: PMC8916731 DOI: 10.1126/sciadv.abj9229] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 01/22/2022] [Indexed: 06/14/2023]
Abstract
Mutations in the brain-specific β-tubulin 4A (TUBB4A) gene cause a broad spectrum of diseases, ranging from dystonia (DYT-TUBB4A) to hypomyelination with atrophy of the basal ganglia and cerebellum (H-ABC). Currently, the mechanisms of how TUBB4A variants lead to this pleiotropic manifestation remain elusive. Here, we investigated whether TUBB4A mutations causing either DYT-TUBB4A (p.R2G and p.Q424H) or H-ABC (p.R2W and p.D249N) exhibit differential effects at the molecular and cellular levels. Using live-cell imaging of disease-relevant oligodendrocytes and total internal reflection fluorescence microscopy of whole-cell lysates, we observed divergent impact on microtubule polymerization and microtubule integration, partially reflecting the observed pleiotropy. Moreover, in silico simulations demonstrated that the mutants rarely adopted a straight heterodimer conformation in contrast to wild type. In conclusion, for most of the examined variants, we deciphered potential molecular disease mechanisms that may lead to the diverse clinical manifestations and phenotype severity across and within each TUBB4A-related disease.
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Affiliation(s)
- Victor Krajka
- Institute of Neurogenetics, University of Lübeck, Ratzeburger Allee 160, 23538 Lübeck, Germany
- Institute of Microtechnology (IMT), Technische Universität Braunschweig, Braunschweig 38124, Germany
| | - Franca Vulinovic
- Institute of Neurogenetics, University of Lübeck, Ratzeburger Allee 160, 23538 Lübeck, Germany
| | - Mariya Genova
- Institut Curie, Université PSL, CNRS UMR3348, 91401 Orsay, France
- Université Paris-Saclay, CNRS UMR3348, 91401 Orsay, France
| | - Kerstin Tanzer
- Institute of Neurogenetics, University of Lübeck, Ratzeburger Allee 160, 23538 Lübeck, Germany
| | - A. S. Jijumon
- Institut Curie, Université PSL, CNRS UMR3348, 91401 Orsay, France
- Université Paris-Saclay, CNRS UMR3348, 91401 Orsay, France
| | - Satish Bodakuntla
- Institut Curie, Université PSL, CNRS UMR3348, 91401 Orsay, France
- Université Paris-Saclay, CNRS UMR3348, 91401 Orsay, France
| | - Stephanie Tennstedt
- Institute for Cardiogenetics, University of Lübeck, 23562 Lübeck, Germany
- DZHK (German Research Centre for Cardiovascular Research), partner site Hamburg/Lübeck/Kiel, 23562 Lübeck, Germany
- University Heart Center Lübeck, 23562 Lübeck, Germany
| | - Helge Mueller-Fielitz
- Institute for Experimental and Clinical Pharmacology and Toxicology, University of Lübeck, Ratzeburger Allee 160, 23562 Lübeck, Germany
| | - Britta Meier
- Institute of Neurogenetics, University of Lübeck, Ratzeburger Allee 160, 23538 Lübeck, Germany
| | - Carsten Janke
- Institut Curie, Université PSL, CNRS UMR3348, 91401 Orsay, France
- Université Paris-Saclay, CNRS UMR3348, 91401 Orsay, France
| | - Christine Klein
- Institute of Neurogenetics, University of Lübeck, Ratzeburger Allee 160, 23538 Lübeck, Germany
| | - Aleksandar Rakovic
- Institute of Neurogenetics, University of Lübeck, Ratzeburger Allee 160, 23538 Lübeck, Germany
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20
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Complementing the phenotypical spectrum of TUBA1A tubulinopathy and its role in early-onset epilepsies. Eur J Hum Genet 2022; 30:298-306. [PMID: 35017693 PMCID: PMC8904761 DOI: 10.1038/s41431-021-01027-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 11/26/2021] [Accepted: 12/09/2021] [Indexed: 12/29/2022] Open
Abstract
TUBA1A tubulinopathy is a rare neurodevelopmental disorder associated with brain malformations as well as early-onset and intractable epilepsy. As pathomechanisms and genotype-phenotype correlations are not completely understood, we aimed to provide further insights into the phenotypic and genetic spectrum. We here present a multicenter case series of ten unrelated individuals from four European countries using systematic MRI re-evaluation, protein structure analysis, and prediction score modeling. In two cases, pregnancy was terminated due to brain malformations. Amongst the eight living individuals, the phenotypic range showed various severity. Global developmental delay and severe motor impairment with tetraparesis was present in 63% and 50% of the subjects, respectively. Epilepsy was observed in 75% of the cases, which showed infantile onset in 83% and a refractory course in 50%. One individual presented a novel TUBA1A-associated electroclinical phenotype with evolvement from early myoclonic encephalopathy to continuous spike-and-wave during sleep. Neuroradiological features comprised a heterogeneous spectrum of cortical and extracortical malformations including rare findings such as cobblestone lissencephaly and subcortical band heterotopia. Two individuals developed hydrocephalus with subsequent posterior infarction. We report four novel and five previously published TUBA1A missense variants whose resulting amino acid substitutions likely affect longitudinal, lateral, and motor protein interactions as well as GTP binding. Assessment of pathogenic and benign variant distributions in synopsis with prediction scores revealed sections of variant enrichment and intolerance to missense variation. We here extend the clinical, neuroradiological, and genetic spectrum of TUBA1A tubulinopathy and provide insights into residue-specific pathomechanisms and genotype-phenotype correlations.
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21
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Fertuzinhos S, Legué E, Li D, Liem KF. A dominant tubulin mutation causes cerebellar neurodegeneration in a genetic model of tubulinopathy. SCIENCE ADVANCES 2022; 8:eabf7262. [PMID: 35171680 PMCID: PMC8849301 DOI: 10.1126/sciadv.abf7262] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 12/22/2021] [Indexed: 06/14/2023]
Abstract
Mutations in tubulins cause distinct neurodevelopmental and degenerative diseases termed "tubulinopathies"; however, little is known about the functional requirements of tubulins or how mutations cause cell-specific pathologies. Here, we identify a mutation in the gene Tubb4a that causes degeneration of cerebellar granule neurons and myelination defects. We show that the neural phenotypes result from a cell type-specific enrichment of a dominant mutant form of Tubb4a relative to the expression other β-tubulin isotypes. Loss of Tubb4a function does not underlie cellular pathology but is compensated by the transcriptional up-regulation of related tubulin genes in a cell type-specific manner. This work establishes that the expression of a primary tubulin mutation in mature neurons is sufficient to promote cell-autonomous cell death, consistent with a causative association of microtubule dysfunction with neurodegenerative diseases. These studies provide evidence that mutations in tubulins cause specific phenotypes based on expression ratios of tubulin isotype genes.
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Affiliation(s)
- Sofia Fertuzinhos
- Vertebrate Developmental Biology Program, Department of Pediatrics, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Emilie Legué
- Vertebrate Developmental Biology Program, Department of Pediatrics, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Davis Li
- Department of Genetics, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Karel F. Liem
- Vertebrate Developmental Biology Program, Department of Pediatrics, Yale University School of Medicine, New Haven, CT 06520, USA
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22
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Çitli Ş, Serdaroglu E. Maternal Germline Mosaicism of a de Novo TUBB2B Mutation Leads to Complex Cortical Dysplasia in Two Siblings. Fetal Pediatr Pathol 2022; 41:155-165. [PMID: 32281916 DOI: 10.1080/15513815.2020.1753270] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Introduction: Complex cortical dysplasia with other brain malformations-7 (a.k.a. polymicrogyria) caused by mutations in TUBB2B gene is a clinically heterogeneous condition. Case report: We report two siblings with polymicrogyria. Brain MRI showed polymicrogyria, small brainstem, thin corpus callosum and fused basal ganglia. Karyotypes and chromosomal microarray analysis were normal. By whole exome sequencing, there were a de novo variant of c.728C > T (p.P243L) in both siblings and a common single nucleotide polymorphism (SNP) (c.718C > T) in both siblings and the mother. Seminal DNA analysis obtained from father was normal. Conclusion: Maternal germline mosaicism was considered because the sequencing result of the father's sperm was normal, two siblings had the same disease, and both patients and mother had the same SNP.
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Affiliation(s)
- Şenol Çitli
- Medical Genetics, Gaziosmanpasa University Medical Faculty, Tokat, Turkey
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23
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Weir N, Stevens B, Wagner S, Miles A, Ball G, Howard C, Chemmarappally J, McGinnity M, Hargreaves AJ, Tinsley C. Aligned Poly-l-lactic Acid Nanofibers Induce Self-Assembly of Primary Cortical Neurons into 3D Cell Clusters. ACS Biomater Sci Eng 2022; 8:765-776. [PMID: 35084839 DOI: 10.1021/acsbiomaterials.1c01102] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Relative to two-dimensional (2D) culture, three-dimensional (3D) culture of primary neurons has yielded increasingly physiological responses from cells. Electrospun nanofiber scaffolds are frequently used as a 3D biomaterial support for primary neurons in neural tissue engineering, while hydrophobic surfaces typically induce aggregation of cells. Poly-l-lactic acid (PLLA) was electrospun as aligned PLLA nanofiber scaffolds to generate a structure with both qualities. Primary cortical neurons from E18 Sprague-Dawley rats cultured on aligned PLLA nanofibers generated 3D clusters of cells that extended highly aligned, fasciculated neurite bundles within 10 days. These clusters were viable for 28 days and responsive to AMPA and GABA. Relative to the 2D culture, the 3D cultures exhibited a more developed profile; mass spectrometry demonstrated an upregulation of proteins involved in cortical lamination, polarization, and axon fasciculation and a downregulation of immature neuronal markers. The use of artificial neural network inference suggests that the increased formation of synapses may drive the increase in development that is observed for the 3D cell clusters. This research suggests that aligned PLLA nanofibers may be highly useful for generating advanced 3D cell cultures for high-throughput systems.
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Affiliation(s)
- Nick Weir
- School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, U.K
| | - Bob Stevens
- School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, U.K
| | - Sarah Wagner
- School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, U.K
| | - Amanda Miles
- School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, U.K
| | - Graham Ball
- School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, U.K
| | - Charlotte Howard
- School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, U.K
| | - Joseph Chemmarappally
- School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, U.K
| | - Martin McGinnity
- School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, U.K
| | - Alan Jeffrey Hargreaves
- School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, U.K
| | - Chris Tinsley
- School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, U.K
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24
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Krishnan RK, Halachmi N, Baskar R, Bakhrat A, Zarivach R, Salzberg A, Abdu U. Revisiting the Role of ß-Tubulin in Drosophila Development: β-tubulin60D is not an Essential Gene, and its Novel Pin1 Allele has a Tissue-Specific Dominant-Negative Impact. Front Cell Dev Biol 2022; 9:787976. [PMID: 35111755 PMCID: PMC8802551 DOI: 10.3389/fcell.2021.787976] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 12/09/2021] [Indexed: 11/19/2022] Open
Abstract
Diversity in cytoskeleton organization and function may be achieved through alternative tubulin isotypes and by a variety of post-translational modifications. The Drosophila genome contains five different β-tubulin paralogs, which may play an isotype tissue-specific function in vivo. One of these genes, the β-tubulin60D gene, which is expressed in a tissue-specific manner, was found to be essential for fly viability and fertility. To further understand the role of the β-tubulin60D gene, we generated new β-tubulin60D null alleles (β-tubulin60DM) using the CRISPR/Cas9 system and found that the homozygous flies were viable and fertile. Moreover, using a combination of genetic complementation tests, rescue experiments, and cell biology analyses, we identified Pin1, an unknown dominant mutant with bristle developmental defects, as a dominant-negative allele of β-tubulin60D. We also found a missense mutation in the Pin1 mutant that results in an amino acid replacement from the highly conserved glutamate at position 75 to lysine (E75K). Analyzing the ß-tubulin structure suggests that this E75K alteration destabilizes the alpha-helix structure and may also alter the GTP-Mg2+ complex binding capabilities. Our results revisited the credence that β-tubulin60D is required for fly viability and revealed for the first time in Drosophila, a novel dominant-negative function of missense β-tubulin60D mutation in bristle morphogenesis.
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Affiliation(s)
| | - Naomi Halachmi
- Department of Genetics and Developmental Biology, Rappaport Faculty of Medicine, Technion, Haifa, Israel
| | - Raju Baskar
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer’Sheva, Israel
| | - Anna Bakhrat
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer’Sheva, Israel
| | - Raz Zarivach
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer’Sheva, Israel
- National Institute for Biotechnology in the Negev and the Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Adi Salzberg
- Department of Genetics and Developmental Biology, Rappaport Faculty of Medicine, Technion, Haifa, Israel
| | - Uri Abdu
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer’Sheva, Israel
- *Correspondence: Uri Abdu,
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25
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Whitman MC, Barry BJ, Robson CD, Facio FM, Van Ryzin C, Chan WM, Lehky TJ, Thurm A, Zalewski C, King KA, Brewer C, Almpani K, Lee JS, Delaney A, FitzGibbon EJ, Lee PR, Toro C, Paul SM, Abdul-Rahman OA, Webb BD, Jabs EW, Moller HU, Larsen DA, Antony JH, Troedson C, Ma A, Ragnhild G, Wirgenes KV, Tham E, Kvarnung M, Maarup TJ, MacKinnon S, Hunter DG, Collins FS, Manoli I, Engle EC. TUBB3 Arg262His causes a recognizable syndrome including CFEOM3, facial palsy, joint contractures, and early-onset peripheral neuropathy. Hum Genet 2021; 140:1709-1731. [PMID: 34652576 PMCID: PMC8656246 DOI: 10.1007/s00439-021-02379-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 09/25/2021] [Indexed: 10/20/2022]
Abstract
Microtubules are formed from heterodimers of alpha- and beta-tubulin, each of which has multiple isoforms encoded by separate genes. Pathogenic missense variants in multiple different tubulin isoforms cause brain malformations. Missense mutations in TUBB3, which encodes the neuron-specific beta-tubulin isotype, can cause congenital fibrosis of the extraocular muscles type 3 (CFEOM3) and/or malformations of cortical development, with distinct genotype-phenotype correlations. Here, we report fourteen individuals from thirteen unrelated families, each of whom harbors the identical NM_006086.4 (TUBB3):c.785G>A (p.Arg262His) variant resulting in a phenotype we refer to as the TUBB3 R262H syndrome. The affected individuals present at birth with ptosis, ophthalmoplegia, exotropia, facial weakness, facial dysmorphisms, and, in most cases, distal congenital joint contractures, and subsequently develop intellectual disabilities, gait disorders with proximal joint contractures, Kallmann syndrome (hypogonadotropic hypogonadism and anosmia), and a progressive peripheral neuropathy during the first decade of life. Subsets may also have vocal cord paralysis, auditory dysfunction, cyclic vomiting, and/or tachycardia at rest. All fourteen subjects share a recognizable set of brain malformations, including hypoplasia of the corpus callosum and anterior commissure, basal ganglia malformations, absent olfactory bulbs and sulci, and subtle cerebellar malformations. While similar, individuals with the TUBB3 R262H syndrome can be distinguished from individuals with the TUBB3 E410K syndrome by the presence of congenital and acquired joint contractures, an earlier onset peripheral neuropathy, impaired gait, and basal ganglia malformations.
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Affiliation(s)
- Mary C Whitman
- Department of Ophthalmology, Boston Children's Hospital, Boston, MA, 02115, USA
- Department of Ophthalmology, Harvard Medical School, Boston, MA, 02115, USA
| | - Brenda J Barry
- Department of Neurology, Boston Children's Hospital, Boston, MA, 02115, USA
- Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Caroline D Robson
- Department of Radiology, Boston Children's Hospital, Boston, MA, 02115, USA
- Department of Radiology, Harvard Medical School, Boston, MA, 02115, USA
| | - Flavia M Facio
- Center for Precision Health Research, National Human Genome Research Institute, National Institutes of Health (NIH), Bethesda, MD, 20892, USA
| | - Carol Van Ryzin
- Center for Precision Health Research, National Human Genome Research Institute, National Institutes of Health (NIH), Bethesda, MD, 20892, USA
| | - Wai-Man Chan
- Department of Neurology, Boston Children's Hospital, Boston, MA, 02115, USA
- Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Tanya J Lehky
- EMG Section, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD, 20892-1404, USA
| | - Audrey Thurm
- Neurodevelopmental and Behavioral Phenotyping Service, National Institute of Mental Health, NIH, Bethesda, MD, 20892, USA
| | - Christopher Zalewski
- Audiology Unit, Otolaryngology Branch, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD, 20892, USA
| | - Kelly A King
- Audiology Unit, Otolaryngology Branch, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD, 20892, USA
| | - Carmen Brewer
- Audiology Unit, Otolaryngology Branch, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD, 20892, USA
| | - Konstantinia Almpani
- National Institute of Dental and Craniofacial Research, NIH, Bethesda, MD, 20892, USA
| | - Janice S Lee
- National Institute of Dental and Craniofacial Research, NIH, Bethesda, MD, 20892, USA
| | - Angela Delaney
- Pediatric Endocrinology and Metabolism, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, 20892, USA
- St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Edmond J FitzGibbon
- Laboratory of Sensorimotor Research, National Eye Institute, NIH, Bethesda, MD, 20892, USA
| | - Paul R Lee
- Center for Precision Health Research, National Human Genome Research Institute, National Institutes of Health (NIH), Bethesda, MD, 20892, USA
- Undiagnosed Diseases Program, National Human Genome Research Institute, NIH, Bethesda, MD, 20892, USA
| | - Camilo Toro
- Undiagnosed Diseases Program, National Human Genome Research Institute, NIH, Bethesda, MD, 20892, USA
| | - Scott M Paul
- Rehabilitation Medicine Department, NIH Clinical Center, Bethesda, MD, 20892, USA
- Departments of Biomedical Engineering and Physical Medicine and Rehabilitation, JHU School of Medicine, Baltimore, MD, 21205, USA
| | - Omar A Abdul-Rahman
- Division of Medical Genetics, University of Mississippi Medical Center, Jackson, MS, 39216, USA
- Munroe-Meyer Institute, Omaha, NE, 68106, USA
- Nebraska Medical Center, Omaha, NE, 68198-5450, USA
| | - Bryn D Webb
- Division of Genetics and Metabolism, Department of Pediatrics, University of Wisconsin - Madison, Madison, WI, USA
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Ethylin Wang Jabs
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
- Department of Cell, Developmental, and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
- Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | | | | | | | | | - Alan Ma
- Children's Hospital Westmead, Westmead, NSW, Australia
- Specialty of Genomic Medicine, University of Sydney, Sydney, Australia
| | - Glad Ragnhild
- Department of Medical Genetics, University Hospital North Norway, Tromsø, Norway
| | - Katrine V Wirgenes
- Department of Medical Genetics, Oslo University Hospital, Oslo, Norway
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Emma Tham
- Clinical Genetics, Karolinska University Hospital, Stockholm, Sweden
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - Malin Kvarnung
- Department of Clinical Genetics, Karolinska University Hospital, Stockholm, Sweden
| | | | - Sarah MacKinnon
- Department of Ophthalmology, Boston Children's Hospital, Boston, MA, 02115, USA
| | - David G Hunter
- Department of Ophthalmology, Boston Children's Hospital, Boston, MA, 02115, USA
- Department of Ophthalmology, Harvard Medical School, Boston, MA, 02115, USA
| | - Francis S Collins
- Center for Precision Health Research, National Human Genome Research Institute, National Institutes of Health (NIH), Bethesda, MD, 20892, USA
- Office of the Director, NIH, Bethesda, MD, 20892, USA
| | - Irini Manoli
- Center for Precision Health Research, National Human Genome Research Institute, National Institutes of Health (NIH), Bethesda, MD, 20892, USA.
| | - Elizabeth C Engle
- Department of Neurology, Boston Children's Hospital, Boston, MA, 02115, USA.
- Howard Hughes Medical Institute, Chevy Chase, MD, USA.
- Kirby Center, Boston Children's Hospital, Boston, MA, 02115, USA.
- Department of Neurology, Harvard Medical School, Boston, MA, 02115, USA.
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26
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New perspectives on cytoskeletal dysregulation and mitochondrial mislocalization in amyotrophic lateral sclerosis. Transl Neurodegener 2021; 10:46. [PMID: 34789332 PMCID: PMC8597313 DOI: 10.1186/s40035-021-00272-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Accepted: 10/28/2021] [Indexed: 02/07/2023] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterized by selective, early degeneration of motor neurons in the brain and spinal cord. Motor neurons have long axonal projections, which rely on the integrity of neuronal cytoskeleton and mitochondria to regulate energy requirements for maintaining axonal stability, anterograde and retrograde transport, and signaling between neurons. The formation of protein aggregates which contain cytoskeletal proteins, and mitochondrial dysfunction both have devastating effects on the function of neurons and are shared pathological features across several neurodegenerative conditions, including ALS, Alzheimer's disease, Parkinson's disease, Huntington's disease and Charcot-Marie-Tooth disease. Furthermore, it is becoming increasingly clear that cytoskeletal integrity and mitochondrial function are intricately linked. Therefore, dysregulations of the cytoskeletal network and mitochondrial homeostasis and localization, may be common pathways in the initial steps of neurodegeneration. Here we review and discuss known contributors, including variants in genetic loci and aberrant protein activities, which modify cytoskeletal integrity, axonal transport and mitochondrial localization in ALS and have overlapping features with other neurodegenerative diseases. Additionally, we explore some emerging pathways that may contribute to this disruption in ALS.
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27
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Dekker J, Diderich KEM, Schot R, Husen SC, Dremmen MHG, Go ATJI, Weerts MJA, van Slegtenhorst MA, Mancini GMS. A novel family illustrating the mild phenotypic spectrum of TUBB2B variants. Eur J Paediatr Neurol 2021; 35:35-39. [PMID: 34592644 DOI: 10.1016/j.ejpn.2021.09.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 08/12/2021] [Accepted: 09/09/2021] [Indexed: 10/20/2022]
Abstract
TUBB2B codes for one of the isotypes of β-tubulin and dominant negative variants in this gene result in distinctive malformations of cortical development (MCD), including dysgyria, dysmorphic basal ganglia and cerebellar anomalies. We present a novel family with a heterozygous missense variant in TUBB2B and an unusually mild phenotype. First, at 21 37 weeks of gestation ultrasonography revealed a fetus with a relatively small head, enlarged lateral ventricles, borderline hypoplastic cerebellum and a thin corpus callosum. The couple opted for pregnancy termination. Exome sequencing on fetal material afterwards identified a heterozygous maternally inherited variant in TUBB2B (NM_178012.4 (TUBB2B):c.530A > T, p.(Asp177Val)), not present in GnomAD and predicted as damaging. The healthy mother had only a language delay in childhood. This inherited TUBB2B variant prompted re-evaluation of the older son of the couple, who presented with a mild delay in motor skills and speech. His MRI revealed mildly enlarged lateral ventricles, a thin corpus callosum, mild cortical dysgyria, and dysmorphic vermis and basal ganglia, a pattern typical of tubulinopathies. This son finally showed the same TUBB2B variant, supporting pathogenicity of the TUBB2B variant. These observations illustrate the wide phenotypic heterogeneity of tubulinopathies, including reduced penetrance and mild expressivity, that require careful evaluation in pre- and postnatal counseling.
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Affiliation(s)
- Jordy Dekker
- Department of Clinical Genetics, Erasmus MC University Medical Center, 3015, GD Rotterdam, the Netherlands
| | - Karin E M Diderich
- Department of Clinical Genetics, Erasmus MC University Medical Center, 3015, GD Rotterdam, the Netherlands
| | - Rachel Schot
- Department of Clinical Genetics, Erasmus MC University Medical Center, 3015, GD Rotterdam, the Netherlands
| | - Sofie C Husen
- Department of Obstetrics and Prenatal Medicine, Erasmus MC University Medical Center, 3015, GD Rotterdam, the Netherlands
| | - Marjolein H G Dremmen
- Department of Radiology and Nuclear Medicine, Erasmus MC University Medical Center, 3015, GD Rotterdam, the Netherlands
| | - Attie T J I Go
- Department of Obstetrics and Prenatal Medicine, Erasmus MC University Medical Center, 3015, GD Rotterdam, the Netherlands
| | - Marjolein J A Weerts
- Department of Clinical Genetics, Erasmus MC University Medical Center, 3015, GD Rotterdam, the Netherlands
| | - Marjon A van Slegtenhorst
- Department of Clinical Genetics, Erasmus MC University Medical Center, 3015, GD Rotterdam, the Netherlands
| | - Grazia M S Mancini
- Department of Clinical Genetics, Erasmus MC University Medical Center, 3015, GD Rotterdam, the Netherlands.
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28
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Chen S, Alhassen W, Vakil Monfared R, Vachirakorntong B, Nauli SM, Baldi P, Alachkar A. Dynamic Changes of Brain Cilia Transcriptomes across the Human Lifespan. Int J Mol Sci 2021; 22:10387. [PMID: 34638726 PMCID: PMC8509004 DOI: 10.3390/ijms221910387] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 09/23/2021] [Accepted: 09/24/2021] [Indexed: 12/27/2022] Open
Abstract
Almost all brain cells contain primary cilia, antennae-like microtubule sensory organelles, on their surface, which play critical roles in brain functions. During neurodevelopmental stages, cilia are essential for brain formation and maturation. In the adult brain, cilia play vital roles as signaling hubs that receive and transduce various signals and regulate cell-to-cell communications. These distinct roles suggest that cilia functions, and probably structures, change throughout the human lifespan. To further understand the age-dependent changes in cilia roles, we identified and analyzed age-dependent patterns of expression of cilia's structural and functional components across the human lifespan. We acquired cilia transcriptomic data for 16 brain regions from the BrainSpan Atlas and analyzed the age-dependent expression patterns using a linear regression model by calculating the regression coefficient. We found that 67% of cilia transcripts were differentially expressed genes with age (DEGAs) in at least one brain region. The age-dependent expression was region-specific, with the highest and lowest numbers of DEGAs expressed in the ventrolateral prefrontal cortex and hippocampus, respectively. The majority of cilia DEGAs displayed upregulation with age in most of the brain regions. The transcripts encoding cilia basal body components formed the majority of cilia DEGAs, and adjacent cerebral cortices exhibited large overlapping pairs of cilia DEGAs. Most remarkably, specific α/β-tubulin subunits (TUBA1A, TUBB2A, and TUBB2B) and SNAP-25 exhibited the highest rates of downregulation and upregulation, respectively, across age in almost all brain regions. α/β-tubulins and SNAP-25 expressions are known to be dysregulated in age-related neurodevelopmental and neurodegenerative disorders. Our results support a role for the high dynamics of cilia structural and functional components across the lifespan in the normal physiology of brain circuits. Furthermore, they suggest a crucial role for cilia signaling in the pathophysiological mechanisms of age-related psychiatric/neurological disorders.
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Affiliation(s)
- Siwei Chen
- Department of Computer Science, School of Information and Computer Sciences, University of California-Irvine, Irvine, CA 92617, USA; (S.C.); (P.B.)
- Institute for Genomics and Bioinformatics, School of Information and Computer Sciences, University of California-Irvine, Irvine, CA 92617, USA
| | - Wedad Alhassen
- Department of Pharmaceutical Sciences, School of Pharmacy, University of California-Irvine, Irvine, CA 92617, USA; (W.A.); (R.V.M.); (B.V.)
| | - Roudabeh Vakil Monfared
- Department of Pharmaceutical Sciences, School of Pharmacy, University of California-Irvine, Irvine, CA 92617, USA; (W.A.); (R.V.M.); (B.V.)
| | - Benjamin Vachirakorntong
- Department of Pharmaceutical Sciences, School of Pharmacy, University of California-Irvine, Irvine, CA 92617, USA; (W.A.); (R.V.M.); (B.V.)
| | - Surya M. Nauli
- Department of Biomedical and Pharmaceutical Sciences, School of Pharmacy, Chapman University Rinker Health Science Campus, Irvine, CA 92618, USA;
| | - Pierre Baldi
- Department of Computer Science, School of Information and Computer Sciences, University of California-Irvine, Irvine, CA 92617, USA; (S.C.); (P.B.)
- Institute for Genomics and Bioinformatics, School of Information and Computer Sciences, University of California-Irvine, Irvine, CA 92617, USA
| | - Amal Alachkar
- Institute for Genomics and Bioinformatics, School of Information and Computer Sciences, University of California-Irvine, Irvine, CA 92617, USA
- Department of Pharmaceutical Sciences, School of Pharmacy, University of California-Irvine, Irvine, CA 92617, USA; (W.A.); (R.V.M.); (B.V.)
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29
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The Names of Things: The 2018 Bernard Sachs Lecture. Pediatr Neurol 2021; 122:41-49. [PMID: 34330614 DOI: 10.1016/j.pediatrneurol.2021.05.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 05/05/2021] [Indexed: 11/22/2022]
Abstract
In 2018, I was honored to receive the Bernard Sachs Award for a lifetime of work expanding knowledge of diverse neurodevelopmental disorders. Summarizing work over more than 30 years is difficult but is an opportunity to chronicle the dramatic changes in the medical and scientific world that have transformed the field of Child Neurology over this time, as reflected in my own work. Here I have chosen to highlight five broad themes of my research beginning with my interest in descriptive terms that drive wider understanding and my choice for the title of this review. From there I will go on to contrast the state of knowledge as I entered the field with the state of knowledge today for four human brain malformations-lissencephaly, megalencephaly, cerebellar malformations, and polymicrogyria. For all, the changes have been dramatic.
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30
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Denarier E, Ecklund KH, Berthier G, Favier A, O'Toole ET, Gory-Fauré S, De Macedo L, Delphin C, Andrieux A, Markus SM, Boscheron C. Modeling a disease-correlated tubulin mutation in budding yeast reveals insight into MAP-mediated dynein function. Mol Biol Cell 2021; 32:ar10. [PMID: 34379441 PMCID: PMC8684761 DOI: 10.1091/mbc.e21-05-0237] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mutations in the genes that encode α- and β-tubulin underlie many neurological diseases, most notably malformations in cortical development. In addition to revealing the molecular basis for disease etiology, studying such mutations can provide insight into microtubule function and the role of the large family of microtubule effectors. In this study, we use budding yeast to model one such mutation—Gly436Arg in α-tubulin, which is causative of malformations in cortical development—in order to understand how it impacts microtubule function in a simple eukaryotic system. Using a combination of in vitro and in vivo methodologies, including live cell imaging and electron tomography, we find that the mutant tubulin is incorporated into microtubules, causes a shift in α-tubulin isotype usage, and dramatically enhances dynein activity, which leads to spindle-positioning defects. We find that the basis for the latter phenotype is an impaired interaction between She1—a dynein inhibitor—and the mutant microtubules. In addition to revealing the natural balance of α-tubulin isotype utilization in cells, our results provide evidence of an impaired interaction between microtubules and a dynein regulator as a consequence of a tubulin mutation and sheds light on a mechanism that may be causative of neurodevelopmental diseases.
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Affiliation(s)
- E Denarier
- Univ. Grenoble Alpes, CEA, CNRS, GIN, IBS, Inserm, IRIG, F-38000 Grenoble, France
| | - K H Ecklund
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, United States
| | - G Berthier
- Univ. Grenoble Alpes, CEA, CNRS, GIN, IBS, Inserm, IRIG, F-38000 Grenoble, France
| | - A Favier
- Univ. Grenoble Alpes, CEA, CNRS, GIN, IBS, Inserm, IRIG, F-38000 Grenoble, France
| | - E T O'Toole
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Boulder, Colorado, United States
| | - S Gory-Fauré
- Univ. Grenoble Alpes, CEA, CNRS, GIN, IBS, Inserm, IRIG, F-38000 Grenoble, France
| | - L De Macedo
- Univ. Grenoble Alpes, CEA, CNRS, GIN, IBS, Inserm, IRIG, F-38000 Grenoble, France
| | - C Delphin
- Univ. Grenoble Alpes, CEA, CNRS, GIN, IBS, Inserm, IRIG, F-38000 Grenoble, France
| | - A Andrieux
- Univ. Grenoble Alpes, CEA, CNRS, GIN, IBS, Inserm, IRIG, F-38000 Grenoble, France
| | - S M Markus
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, United States
| | - C Boscheron
- Univ. Grenoble Alpes, CEA, CNRS, GIN, IBS, Inserm, IRIG, F-38000 Grenoble, France
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31
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Alata M, González-Vega A, Piazza V, Kleinert-Altamirano A, Cortes C, Ahumada-Juárez JC, Eguibar JR, López-Juárez A, Hernandez VH. Longitudinal Evaluation of Cerebellar Signs of H-ABC Tubulinopathy in a Patient and in the taiep Model. Front Neurol 2021; 12:702039. [PMID: 34335454 PMCID: PMC8317997 DOI: 10.3389/fneur.2021.702039] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 06/08/2021] [Indexed: 01/20/2023] Open
Abstract
Hypomyelination with atrophy of the basal ganglia and cerebellum (H-ABC) is a central neurodegenerative disease due to mutations in the tubulin beta-4A (TUBB4A) gene, characterized by motor development delay, abnormal movements, ataxia, spasticity, dysarthria, and cognitive deficits. Diagnosis is made by integrating clinical data and radiological signs. Differences in MRIs have been reported in patients that carry the same mutation; however, a quantitative study has not been performed so far. Our study aimed to provide a longitudinal analysis of the changes in the cerebellum (Cb), corpus callosum (CC), ventricular system, and striatum in a patient suffering from H-ABC and in the taiep rat. We correlated the MRI signs of the patient with the results of immunofluorescence, gait analysis, segmentation of cerebellum, CC, and ventricular system, performed in the taiep rat. We found that cerebellar and callosal changes, suggesting a potential hypomyelination, worsened with age, in concomitance with the emergence of ataxic gait. We also observed a progressive lateral ventriculomegaly in both patient and taiep, possibly secondary to the atrophy of the white matter. These white matter changes are progressive and can be involved in the clinical deterioration. Hypomyelination with atrophy of the basal ganglia and cerebellum (H-ABC) gives rise to a spectrum of clinical signs whose pathophysiology still needs to be understood.
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Affiliation(s)
| | - Arturo González-Vega
- Department of Chemical, Electronic and Biomedical Engineering, Division of Sciences and Engineering, University of Guanajuato, Guanajuato, Mexico
| | | | | | - Carmen Cortes
- Behavioral Neurophysiology Lab, Institute of Physiology, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Juan C Ahumada-Juárez
- Behavioral Neurophysiology Lab, Institute of Physiology, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Jose R Eguibar
- Behavioral Neurophysiology Lab, Institute of Physiology, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico.,Research Office, Vicerrectory of Research and Postgraduate Studies, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Alejandra López-Juárez
- Department of Chemical, Electronic and Biomedical Engineering, Division of Sciences and Engineering, University of Guanajuato, Guanajuato, Mexico
| | - Victor H Hernandez
- Department of Chemical, Electronic and Biomedical Engineering, Division of Sciences and Engineering, University of Guanajuato, Guanajuato, Mexico
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Alhassen W, Chen S, Vawter M, Robbins BK, Nguyen H, Myint TN, Saito Y, Schulmann A, Nauli SM, Civelli O, Baldi P, Alachkar A. Patterns of cilia gene dysregulations in major psychiatric disorders. Prog Neuropsychopharmacol Biol Psychiatry 2021; 109:110255. [PMID: 33508383 PMCID: PMC9121176 DOI: 10.1016/j.pnpbp.2021.110255] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 01/06/2021] [Accepted: 01/16/2021] [Indexed: 12/15/2022]
Abstract
Primary cilia function as cells' antennas to detect and transduce external stimuli and play crucial roles in cell signaling and communication. The vast majority of cilia genes that are causally linked with ciliopathies are also associated with neurological deficits, such as cognitive impairments. Yet, the roles of cilia dysfunctions in the pathogenesis of psychiatric disorders have not been studied. Our aim is to identify patterns of cilia gene dysregulation in the four major psychiatric disorders: schizophrenia (SCZ), autism spectrum disorder (ASD), bipolar disorder (BP), and major depressive disorder (MDD). For this purpose, we acquired differentially expressed genes (DEGs) from the largest and most recent publicly available databases. We found that 42%, 24%, 17%, and 15% of brain-expressed cilia genes were significantly differentially expressed in SCZ, ASD, BP, and MDD, respectively. Several genes exhibited cross-disorder overlap, suggesting that typical cilia signaling pathways' dysfunctions determine susceptibility to more than one psychiatric disorder or may partially underlie their pathophysiology. Our study revealed that genes encoding proteins of almost all sub-cilia structural and functional compartments were dysregulated in the four psychiatric disorders. Strikingly, the genes of 75% of cilia GPCRs and 50% of the transition zone proteins were differentially expressed in SCZ. The present study is the first to draw associations between cilia and major psychiatric disorders, and is the first step toward understanding the role that cilia components play in their pathophysiological processes, which may lead to novel therapeutic targets for these disorders.
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Affiliation(s)
- Wedad Alhassen
- Departments of Pharmaceutical Sciences, School of Pharmacy, University of California-Irvine, CA 92697, USA
| | - Siwei Chen
- Department of Computer Science, School of Information and Computer Sciences, University of California-Irvine, Irvine, CA 92697, USA,Institute for Genomics and Bioinformatics, School of Information and Computer Sciences, University of California-Irvine, CA 92697, USA
| | - Marquis Vawter
- Department of Psychiatry and Human Behavior, School of Medicine, University of California, Irvine, USA
| | - Brianna Kay Robbins
- Departments of Pharmaceutical Sciences, School of Pharmacy, University of California-Irvine, CA 92697, USA
| | - Henry Nguyen
- Departments of Pharmaceutical Sciences, School of Pharmacy, University of California-Irvine, CA 92697, USA
| | - Thant Nyi Myint
- Departments of Pharmaceutical Sciences, School of Pharmacy, University of California-Irvine, CA 92697, USA
| | - Yumiko Saito
- Graduate School of Integrated Arts and Sciences for Life, Hiroshima University, Japan
| | - Anton Schulmann
- Human Genetics Branch, National Institute of Mental Health, BETHESDA MD 20814, USA
| | - Surya M. Nauli
- Department of Biomedical and Pharmaceutical Sciences, School of Pharmacy, Chapman University, Health Science Campus, Chapman University, Irvine, California 92618, USA
| | - Olivier Civelli
- Departments of Pharmaceutical Sciences, School of Pharmacy, University of California-Irvine, CA 92697, USA,Department of Developmental and Cell Biology, School of Biological Sciences, University of California-Irvine, CA 92697, USA
| | - Pierre Baldi
- Department of Computer Science, School of Information and Computer Sciences, University of California-Irvine, Irvine, CA 92697, USA,Institute for Genomics and Bioinformatics, School of Information and Computer Sciences, University of California-Irvine, CA 92697, USA
| | - Amal Alachkar
- Departments of Pharmaceutical Sciences, School of Pharmacy, University of California-, Irvine, CA 92697, USA; Department of Computer Science, School of Information and Computer Sciences, University of California-Irvine, Irvine, CA 92697, USA.
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Whitman MC. Axonal Growth Abnormalities Underlying Ocular Cranial Nerve Disorders. Annu Rev Vis Sci 2021; 7:827-850. [PMID: 34081534 DOI: 10.1146/annurev-vision-093019-114307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Abnormalities in cranial motor nerve development cause paralytic strabismus syndromes, collectively referred to as congenital cranial dysinnervation disorders, in which patients cannot fully move their eyes. These disorders can arise through one of two mechanisms: (a) defective motor neuron specification, usually by loss of a transcription factor necessary for brainstem patterning, or (b) axon growth and guidance abnormalities of the oculomotor, trochlear, and abducens nerves. This review focuses on our current understanding of axon guidance mechanisms in the cranial motor nerves and how disease-causing mutations disrupt axon targeting. Abnormalities of axon growth and guidance are often limited to a single nerve or subdivision, even when the causative gene is ubiquitously expressed. Additionally, when one nerve is absent, its normal target muscles attract other motor neurons. Study of these disorders highlights the complexities of axon guidance and how each population of neurons uses a unique but overlapping set of axon guidance pathways. Expected final online publication date for the Annual Review of Vision Science, Volume 7 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Mary C Whitman
- Department of Ophthalmology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA;
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Jurgens JA, Barry BJ, Lemire G, Chan WM, Whitman MC, Shaaban S, Robson CD, MacKinnon S, England EM, McMillan HJ, Kelly C, Pratt BM, O’Donnell-Luria A, MacArthur DG, Boycott KM, Hunter DG, Engle EC. Novel variants in TUBA1A cause congenital fibrosis of the extraocular muscles with or without malformations of cortical brain development. Eur J Hum Genet 2021; 29:816-826. [PMID: 33649541 PMCID: PMC8110841 DOI: 10.1038/s41431-020-00804-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 12/12/2020] [Accepted: 12/17/2020] [Indexed: 01/31/2023] Open
Abstract
Variants in multiple tubulin genes have been implicated in neurodevelopmental disorders, including malformations of cortical development (MCD) and congenital fibrosis of the extraocular muscles (CFEOM). Distinct missense variants in the beta-tubulin encoding genes TUBB3 and TUBB2B cause MCD, CFEOM, or both, suggesting substitution-specific mechanisms. Variants in the alpha tubulin-encoding gene TUBA1A have been associated with MCD, but not with CFEOM. Using exome sequencing (ES) and genome sequencing (GS), we identified 3 unrelated probands with CFEOM who harbored novel heterozygous TUBA1A missense variants c.1216C>G, p.(His406Asp); c.467G>A, p.(Arg156His); and c.1193T>G, p.(Met398Arg). MRI revealed small oculomotor-innervated muscles and asymmetrical caudate heads and lateral ventricles with or without corpus callosal thinning. Two of the three probands had MCD. Mutated amino acid residues localize either to the longitudinal interface at which α and β tubulins heterodimerize (Met398, His406) or to the lateral interface at which tubulin protofilaments interact (Arg156), and His406 interacts with the motor domain of kinesin-1. This series of individuals supports TUBA1A variants as a cause of CFEOM and expands our knowledge of tubulinopathies.
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Affiliation(s)
- Julie A. Jurgens
- F.M. Kirby Neurobiology Center, Boston Children’s Hospital, Boston, MA USA ,Department of Neurology, Boston Children’s Hospital, Boston, MA USA ,Department of Neurology, Harvard Medical School, Boston, MA USA ,Broad Institute of MIT and Harvard, Cambridge, MA USA
| | - Brenda J. Barry
- Department of Neurology, Boston Children’s Hospital, Boston, MA USA ,Howard Hughes Medical Institute, Chevy Chase, MD USA
| | - Gabrielle Lemire
- Children’s Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, ON Canada
| | - Wai-Man Chan
- F.M. Kirby Neurobiology Center, Boston Children’s Hospital, Boston, MA USA ,Department of Neurology, Boston Children’s Hospital, Boston, MA USA ,Department of Neurology, Harvard Medical School, Boston, MA USA ,Broad Institute of MIT and Harvard, Cambridge, MA USA ,Howard Hughes Medical Institute, Chevy Chase, MD USA
| | - Mary C. Whitman
- F.M. Kirby Neurobiology Center, Boston Children’s Hospital, Boston, MA USA ,Department of Ophthalmology, Boston Children’s Hospital, Boston, MA USA ,Department of Ophthalmology, Harvard Medical School, Boston, MA USA
| | - Sherin Shaaban
- F.M. Kirby Neurobiology Center, Boston Children’s Hospital, Boston, MA USA ,Department of Neurology, Boston Children’s Hospital, Boston, MA USA ,Department of Neurology, Harvard Medical School, Boston, MA USA ,Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT USA
| | - Caroline D. Robson
- Division of Neuroradiology, Department of Radiology, Boston Children’s Hospital, Boston, MA USA ,Department of Radiology, Harvard Medical School, Boston, MA USA
| | - Sarah MacKinnon
- Department of Ophthalmology, Boston Children’s Hospital, Boston, MA USA ,Department of Ophthalmology, Harvard Medical School, Boston, MA USA
| | - Eleina M. England
- Center for Mendelian Genomics, Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA USA ,Analytic and Translational Genetics Unit, Massachusetts General Hospital, Boston, MA USA ,Division of Genetics and Genomics, Boston Children’s Hospital, Boston, MA USA
| | - Hugh J. McMillan
- Division of Neurology, Department of Pediatrics, Children’s Hospital of Eastern Ontario, Ottawa, ON Canada
| | - Christopher Kelly
- Pediatric Ophthalmology and Physician Informatics, MultiCare Health System, Tacoma, WA USA
| | - Brandon M. Pratt
- F.M. Kirby Neurobiology Center, Boston Children’s Hospital, Boston, MA USA ,Department of Neurology, Boston Children’s Hospital, Boston, MA USA ,Department of Neurology, Harvard Medical School, Boston, MA USA
| | | | - Anne O’Donnell-Luria
- Center for Mendelian Genomics, Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA USA ,Analytic and Translational Genetics Unit, Massachusetts General Hospital, Boston, MA USA ,Division of Genetics and Genomics, Boston Children’s Hospital, Boston, MA USA
| | - Daniel G. MacArthur
- Center for Mendelian Genomics, Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA USA ,Analytic and Translational Genetics Unit, Massachusetts General Hospital, Boston, MA USA ,Centre for Population Genomics, Garvan Institute of Medical Research and UNSW, Sydney, NSW Australia ,Murdoch Children’s Research Institute, Parkville, VIC Australia
| | - Kym M. Boycott
- Children’s Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, ON Canada ,Department of Genetics, Children’s Hospital of Eastern Ontario, Ottawa, ON Canada
| | - David G. Hunter
- Department of Ophthalmology, Boston Children’s Hospital, Boston, MA USA ,Department of Ophthalmology, Harvard Medical School, Boston, MA USA
| | - Elizabeth C. Engle
- F.M. Kirby Neurobiology Center, Boston Children’s Hospital, Boston, MA USA ,Department of Neurology, Boston Children’s Hospital, Boston, MA USA ,Department of Neurology, Harvard Medical School, Boston, MA USA ,Broad Institute of MIT and Harvard, Cambridge, MA USA ,Howard Hughes Medical Institute, Chevy Chase, MD USA ,Department of Ophthalmology, Boston Children’s Hospital, Boston, MA USA ,Department of Ophthalmology, Harvard Medical School, Boston, MA USA
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Zhang D, Hugo W, Redublo P, Miao H, Bergsneider M, Wang MB, Kim W, Yong WH, Heaney AP. A human ACTH-secreting corticotroph tumoroid model: Novel Human ACTH-Secreting Tumor Cell in vitro Model. EBioMedicine 2021; 66:103294. [PMID: 33773184 PMCID: PMC8024915 DOI: 10.1016/j.ebiom.2021.103294] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 03/06/2021] [Accepted: 03/08/2021] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND Cushing disease (CD), although rare, is a life-threatening disorder caused by an adrenocorticotropic hormone (ACTH)-secreting pituitary adenoma, which leads to excess adrenal-derived cortisol. Efficacious and safe medical therapies that control both hormonal hypersecretion and pituitary corticotroph tumor growth remain an unmet need in the management of CD. Translational research in pituitary tumors has been significantly hampered by limited quantities of surgically resected tissue for ex vivo studies, and unavailability of human pituitary tumor cell models. METHODS To characterize human corticotroph tumors at the cellular level, we employed single cell RNA-sequencing (scRNA-seq) to study 4 surgically resected tumors. We also used microarrays to compare individualized paired consecutive culture passages to understand transcriptional shifts as in vitro cultures lost ACTH secretion. Based on these findings, we then modified our in vitro culture methods to develop sustained ACTH-secreting human corticotroph tumoroid cultures. FINDINGS scRNA-seq identified 4 major cell populations, namely corticotroph tumor (73.6%), stromal (11.2%), progenitor (8.3%), and immune cells (6.8%). Microarray analysis revealed striking changes in extracellular matrix, cell adhesion and motility-related genes concordant with loss of ACTH secretion during conventional 2D culture. Based on these findings, we subsequently defined a series of crucial culture nutrients and scaffold modifications that provided a more favorable trophic and structural environment that could maintain ACTH secretion in in vitro human corticotroph tumor cultures for up to 4 months. INTERPRETATION Our human corticotroph tumoroid model is a significant advance in the field of pituitary tumors and will further enable translational research studies to identify critically needed therapies for CD. FUNDING This work was partly funded by NCI P50-CA211015 and the Warley Trust Foundation.
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Affiliation(s)
- Dongyun Zhang
- Departments of Medicine, David Geffen School of Medicine, University of California, Los Angeles, United States
| | - Willy Hugo
- Departments of Medicine, David Geffen School of Medicine, University of California, Los Angeles, United States
| | - Peter Redublo
- Departments of Medicine, David Geffen School of Medicine, University of California, Los Angeles, United States
| | - Hui Miao
- Departments of Medicine, David Geffen School of Medicine, University of California, Los Angeles, United States
| | - Marvin Bergsneider
- Departments of Neurosurgery, David Geffen School of Medicine, University of California, Los Angeles, United States
| | - Marilene B Wang
- Departments of Head and Neck Surgery, David Geffen School of Medicine, University of California, Los Angeles, United States
| | - Won Kim
- Departments of Neurosurgery, David Geffen School of Medicine, University of California, Los Angeles, United States
| | - William H Yong
- Departments of Pathology and Lab Medicine, David Geffen School of Medicine, University of California, Los Angeles, United States
| | - Anthony P Heaney
- Departments of Medicine, David Geffen School of Medicine, University of California, Los Angeles, United States; Departments of Neurosurgery, David Geffen School of Medicine, University of California, Los Angeles, United States.
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36
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Brock S, Cools F, Jansen AC. Neuropathology of genetically defined malformations of cortical development-A systematic literature review. Neuropathol Appl Neurobiol 2021; 47:585-602. [PMID: 33480109 PMCID: PMC8359484 DOI: 10.1111/nan.12696] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 12/31/2020] [Accepted: 01/15/2021] [Indexed: 12/23/2022]
Abstract
AIMS Malformations of cortical development (MCD) include a heterogeneous spectrum of clinical, imaging, molecular and histopathological entities. While the understanding of genetic causes of MCD has improved with the availability of next-generation sequencing modalities, genotype-histopathological correlations remain limited. This is the first systematic review of molecular and neuropathological findings in patients with MCD to provide a comprehensive overview of the literature. METHODS A systematic review was performed between November 2019 and February 2020. A MEDLINE search was conducted for 132 genes previously linked to MCD in order to identify studies reporting macroscopic and/or microscopic findings in patients with a confirmed genetic cause. RESULTS Eighty-one studies were included in this review reporting neuropathological features associated with pathogenic variants in 46 genes (46/132 genes, 34.8%). Four groups emerged, consisting of (1) 13 genes with well-defined histological-genotype correlations, (2) 27 genes for which neuropathological reports were limited, (3) 5 genes with conflicting neuropathological features, and (4) 87 genes for which no histological data were available. Lissencephaly and polymicrogyria were reported most frequently. Associated brain malformations were variably present, with abnormalities of the corpus callosum as most common associated feature. CONCLUSIONS Neuropathological data in patients with MCD with a defined genetic cause are available only for a small number of genes. As each genetic cause might lead to unique histopathological features of MCD, standardised thorough neuropathological assessment and reporting should be encouraged. Histological features can help improve the understanding of the pathogenesis of MCD and generate hypotheses with impact on further research directions.
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Affiliation(s)
- Stefanie Brock
- Department of Pathology, Universitair Ziekenhuis Brussel (UZ Brussel), Brussels, Belgium.,Neurogenetics Research Group, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Filip Cools
- Department of Neonatology, Universitair Ziekenhuis Brussel (UZ Brussel), Brussels, Belgium
| | - Anna C Jansen
- Neurogenetics Research Group, Vrije Universiteit Brussel (VUB), Brussels, Belgium.,Pediatric Neurology Unit, Universitair Ziekenhuis Brussel (UZ Brussel), Brussels, Belgium
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Fourel G, Boscheron C. Tubulin mutations in neurodevelopmental disorders as a tool to decipher microtubule function. FEBS Lett 2020; 594:3409-3438. [PMID: 33064843 DOI: 10.1002/1873-3468.13958] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 09/28/2020] [Accepted: 10/05/2020] [Indexed: 01/08/2023]
Abstract
Malformations of cortical development (MCDs) are a group of severe brain malformations associated with intellectual disability and refractory childhood epilepsy. Human missense heterozygous mutations in the 9 α-tubulin and 10 β-tubulin isoforms forming the heterodimers that assemble into microtubules (MTs) were found to cause MCDs. However, how a single mutated residue in a given tubulin isoform can perturb the entire microtubule population in a neuronal cell remains a crucial question. Here, we examined 85 MCD-associated tubulin mutations occurring in TUBA1A, TUBB2, and TUBB3 and their location in a three-dimensional (3D) microtubule cylinder. Mutations hitting residues exposed on the outer microtubule surface are likely to alter microtubule association with partners, while alteration of intradimer contacts may impair dimer stability and straightness. Other types of mutations are predicted to alter interdimer and lateral contacts, which are responsible for microtubule cohesion, rigidity, and dynamics. MCD-associated tubulin mutations surprisingly fall into all categories, thus providing unexpected insights into how a single mutation may impair microtubule function and elicit dominant effects in neurons.
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Leca I, Phillips AW, Hofer I, Landler L, Ushakova L, Cushion TD, Dürnberger G, Stejskal K, Mechtler K, Keays DA. A proteomic survey of microtubule-associated proteins in a R402H TUBA1A mutant mouse. PLoS Genet 2020; 16:e1009104. [PMID: 33137126 PMCID: PMC7660477 DOI: 10.1371/journal.pgen.1009104] [Citation(s) in RCA: 8] [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: 04/06/2020] [Revised: 11/12/2020] [Accepted: 09/08/2020] [Indexed: 11/25/2022] Open
Abstract
Microtubules play a critical role in multiple aspects of neurodevelopment, including the generation, migration and differentiation of neurons. A recurrent mutation (R402H) in the α-tubulin gene TUBA1A is known to cause lissencephaly with cerebellar and striatal phenotypes. Previous work has shown that this mutation does not perturb the chaperone-mediated folding of tubulin heterodimers, which are able to assemble and incorporate into the microtubule lattice. To explore the molecular mechanisms that cause the disease state we generated a new conditional mouse line that recapitulates the R402H variant. We show that heterozygous mutants present with laminar phenotypes in the cortex and hippocampus, as well as a reduction in striatal size and cerebellar abnormalities. We demonstrate that homozygous expression of the R402H allele causes neuronal death and exacerbates a cell intrinsic defect in cortical neuronal migration. Microtubule sedimentation assays coupled with quantitative mass spectrometry demonstrated that the binding and/or levels of multiple microtubule associated proteins (MAPs) are perturbed by the R402H mutation including VAPB, REEP1, EZRIN, PRNP and DYNC1l1/2. Consistent with these data we show that the R402H mutation impairs dynein-mediated transport which is associated with a decoupling of the nucleus to the microtubule organising center. Our data support a model whereby the R402H variant is able to fold and incorporate into microtubules, but acts as a gain of function by perturbing the binding of MAPs. Microtubules are polymers composed of tubulin proteins, which play an important role in the development of the human brain. Genetic mutations in tubulin genes are known to cause neurodevelopmental diseases, including lissencephaly which is characterised by an impairment in the migration of neurons. In this study we investigate how a common mutation (R402H) in TUBA1A causes lissencephaly by generating and characterising a mouse with the same variant. We show that affected animals recapitulate multiple aspects of the human disease; including laminar perturbations in the cortex and hippocampus, attributable to defects in neuronal migration at key developmental time points. To characterize the molecular implications of the R402H mutation we purified microtubules from the developing brain, and analysed the proteins present by mass spectrometry. This revealed that the binding of DYNC1I1/2 to microtubules is altered in mice with the R402H mutation. Our results provide insight into the molecular pathology underlying tubulin related disease states, and provide a foundation for the rational design of therapeutic interventions.
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Affiliation(s)
- Ines Leca
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria
| | | | - Iris Hofer
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria
| | - Lukas Landler
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria
- Institute of Zoology, University of Natural Resources and Life Sciences (BOKU), Vienna, Austria
| | - Lyubov Ushakova
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria
| | - Thomas David Cushion
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria
| | - Gerhard Dürnberger
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna Biocenter (VBC), Vienna, Austria
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna Biocenter (VBC), Vienna, Austria
| | - Karel Stejskal
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna Biocenter (VBC), Vienna, Austria
| | - Karl Mechtler
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna Biocenter (VBC), Vienna, Austria
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna Biocenter (VBC), Vienna, Austria
| | - David Anthony Keays
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria
- Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Australia
- Division of Neurobiology, Department Biology II, Ludwig-Maximilians-University Munich, Planegg-Martinsried 82152, Germany
- * E-mail:
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Schröter J, Döring JH, Garbade SF, Hoffmann GF, Kölker S, Ries M, Syrbe S. Cross-sectional quantitative analysis of the natural history of TUBA1A and TUBB2B tubulinopathies. Genet Med 2020; 23:516-523. [PMID: 33082561 PMCID: PMC7935713 DOI: 10.1038/s41436-020-01001-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 09/25/2020] [Accepted: 09/28/2020] [Indexed: 11/09/2022] Open
Abstract
Purpose TUBA1A and TUBB2B tubulinopathies are rare neurodevelopmental disorders characterized by cortical and extracortical malformations and heterogenic phenotypes. There is a need for quantitative clinical endpoints that will be beneficial for future diagnostic and therapeutic trials. Methods Quantitative natural history modeling of individuals with TUBA1A and TUBB2B tubulinopathies from clinical reports and database entries of DECIPHER and ClinVar. Main outcome measures were age at disease onset, survival, and diagnostic delay. Phenotypical, neuroradiological, and histopathological features were descriptively illustrated. Results Mean age at disease onset was 4 (TUBA1A) and 6 months (TUBB2B), respectively. Mortality was equally estimated with 7% at 3.2 (TUBA1A) and 8.0 years (TUBB2B). Diagnostic delay was significantly higher in TUBB2B (12.3 years) compared with TUBA1A tubulinopathy (4.2 years). We delineated the isotype-dependent clinical, neuroradiological, and histopathological phenotype of affected individuals and present brain malformations associated with epilepsy and an unfavorable course of disease. Conclusion The natural history of tubulinopathies is defined by the genotype and associated brain malformations. Defined data on estimated survival, diagnostic delay, and disease characteristics of TUBA1A and TUBB2B tubulinopathy will help to raise disease awareness and encourage future clinical trials to optimize genetic testing, family counseling, and supportive care.
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Affiliation(s)
- Julian Schröter
- Division of Pediatric Epileptology, Center for Pediatrics and Adolescent Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - Jan H Döring
- Division of Pediatric Epileptology, Center for Pediatrics and Adolescent Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - Sven F Garbade
- Division of Neuropediatrics and Inherited Metabolic Diseases, Center for Pediatrics and Adolescent Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - Georg F Hoffmann
- Division of Neuropediatrics and Inherited Metabolic Diseases, Center for Pediatrics and Adolescent Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - Stefan Kölker
- Division of Neuropediatrics and Inherited Metabolic Diseases, Center for Pediatrics and Adolescent Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - Markus Ries
- Division of Neuropediatrics and Inherited Metabolic Diseases, Center for Pediatrics and Adolescent Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - Steffen Syrbe
- Division of Pediatric Epileptology, Center for Pediatrics and Adolescent Medicine, University Hospital Heidelberg, Heidelberg, Germany.
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40
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Shao DD, Achkar CM, Lai A, Srivastava S, Doan RN, Rodan LH, Chen AY, Poduri A, Yang E, Walsh CA. Polymicrogyria is Associated With Pathogenic Variants in PTEN. Ann Neurol 2020; 88:1153-1164. [PMID: 32959437 DOI: 10.1002/ana.25904] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 09/14/2020] [Accepted: 09/14/2020] [Indexed: 01/22/2023]
Abstract
OBJECTIVE Congenital structural brain malformations have been described in patients with pathogenic phosphatase and tensin homologue (PTEN) variants, but the frequency of cortical malformations in patients with PTEN variants and their impact on clinical phenotype are not well understood. Our goal was to systematically characterize brain malformations in patients with PTEN variants and assess the relevance of their brain malformations to clinical presentation. METHODS We systematically searched a local radiology database for patients with PTEN variants who had available brain magnetic resonance imaging (MRI). The MRI scans were reviewed systematically for cortical abnormalities. We reviewed electroencephalogram (EEG) data and evaluated the electronic medical record for evidence of epilepsy and developmental delay. RESULTS In total, we identified 22 patients with PTEN pathogenic variants for which brain MRIs were available (age range 0.4-17 years). Twelve among these 22 patients (54%) had polymicrogyria (PMG). Variants associated with PMG or atypical gyration encoded regions of the phosphatase or C2 domains of PTEN. Interestingly, epilepsy was present in only 2 of the 12 patients with PMG. We found a trend toward higher rates of global developmental delay (GDD), intellectual disability (ID), and motor delay in individuals with cortical abnormalities, although cohort size limited statistical significance. INTERPRETATION Malformations of cortical development, PMG in particular, represent an under-recognized phenotype associated with PTEN pathogenic variants and may have an association with cognitive and motor delays. Epilepsy was infrequent compared to the previously reported high risk of epilepsy in patients with PMG. ANN NEUROL 2020;88:1153-1164.
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Affiliation(s)
- Diane D Shao
- Department of Neurology, Boston Children's Hospital, Boston, MA, USA.,Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Department of Pediatrics, Boston Children's Hospital, Boston, MA, USA.,Departments of Neurology and Pediatrics, Harvard Medical School, Boston, MA, USA
| | - Christelle M Achkar
- Department of Neurology, Boston Children's Hospital, Boston, MA, USA.,Departments of Neurology and Pediatrics, Harvard Medical School, Boston, MA, USA.,Division of Epilepsy, Department of Neurology, Boston Children's Hospital, Boston, MA, USA
| | - Abbe Lai
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Department of Pediatrics, Boston Children's Hospital, Boston, MA, USA
| | - Siddharth Srivastava
- Department of Neurology, Boston Children's Hospital, Boston, MA, USA.,Departments of Neurology and Pediatrics, Harvard Medical School, Boston, MA, USA
| | - Ryan N Doan
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Department of Pediatrics, Boston Children's Hospital, Boston, MA, USA
| | - Lance H Rodan
- Department of Neurology, Boston Children's Hospital, Boston, MA, USA.,Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Department of Pediatrics, Boston Children's Hospital, Boston, MA, USA.,Departments of Neurology and Pediatrics, Harvard Medical School, Boston, MA, USA
| | - Allen Y Chen
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Department of Pediatrics, Boston Children's Hospital, Boston, MA, USA.,Department of Medicine, Weill Cornell Medicine, New York, NY, USA.,Department of Medicine, Hospital for Special Surgery, New York, NY, USA
| | | | - Annapurna Poduri
- Department of Neurology, Boston Children's Hospital, Boston, MA, USA.,Departments of Neurology and Pediatrics, Harvard Medical School, Boston, MA, USA.,Division of Epilepsy, Department of Neurology, Boston Children's Hospital, Boston, MA, USA
| | - Edward Yang
- Department of Radiology, Boston Children's Hospital, Boston, MA, USA.,Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - Christopher A Walsh
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Department of Pediatrics, Boston Children's Hospital, Boston, MA, USA.,Departments of Neurology and Pediatrics, Harvard Medical School, Boston, MA, USA.,Howard Hughes Medical Institute, Chevy Chase, MD, USA.,Broad Institute of MIT and Harvard, Cambridge, MA, USA
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41
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Microtubule Dysfunction: A Common Feature of Neurodegenerative Diseases. Int J Mol Sci 2020; 21:ijms21197354. [PMID: 33027950 PMCID: PMC7582320 DOI: 10.3390/ijms21197354] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 09/24/2020] [Accepted: 10/01/2020] [Indexed: 12/13/2022] Open
Abstract
Neurons are particularly susceptible to microtubule (MT) defects and deregulation of the MT cytoskeleton is considered to be a common insult during the pathogenesis of neurodegenerative disorders. Evidence that dysfunctions in the MT system have a direct role in neurodegeneration comes from findings that several forms of neurodegenerative diseases are associated with changes in genes encoding tubulins, the structural units of MTs, MT-associated proteins (MAPs), or additional factors such as MT modifying enzymes which modulating tubulin post-translational modifications (PTMs) regulate MT functions and dynamics. Efforts to use MT-targeting therapeutic agents for the treatment of neurodegenerative diseases are underway. Many of these agents have provided several benefits when tested on both in vitro and in vivo neurodegenerative model systems. Currently, the most frequently addressed therapeutic interventions include drugs that modulate MT stability or that target tubulin PTMs, such as tubulin acetylation. The purpose of this review is to provide an update on the relevance of MT dysfunctions to the process of neurodegeneration and briefly discuss advances in the use of MT-targeting drugs for the treatment of neurodegenerative disorders.
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Abstract
It is increasingly recognized that local protein synthesis (LPS) contributes to fundamental aspects of axon biology, in both developing and mature neurons. Mutations in RNA-binding proteins (RBPs), as central players in LPS, and other proteins affecting RNA localization and translation are associated with a range of neurological disorders, suggesting disruption of LPS may be of pathological significance. In this review, we substantiate this hypothesis by examining the link between LPS and key axonal processes, and the implicated pathophysiological consequences of dysregulated LPS. First, we describe how the length and autonomy of axons result in an exceptional reliance on LPS. We next discuss the roles of LPS in maintaining axonal structural and functional polarity and axonal trafficking. We then consider how LPS facilitates the establishment of neuronal connectivity through regulation of axonal branching and pruning, how it mediates axonal survival into adulthood and its involvement in neuronal stress responses.
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Affiliation(s)
- Julie Qiaojin Lin
- UK Dementia Research Institute at University of Cambridge, Department of Clinical Neurosciences, Island Research Building, Cambridge Biomedical Campus, Cambridge, UK
| | | | - Christine E Holt
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
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43
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A seven-gene signature model predicts overall survival in kidney renal clear cell carcinoma. Hereditas 2020; 157:38. [PMID: 32883362 PMCID: PMC7470605 DOI: 10.1186/s41065-020-00152-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Accepted: 08/26/2020] [Indexed: 12/11/2022] Open
Abstract
Background Kidney renal clear cell carcinoma (KIRC) is a potentially fatal urogenital disease. It is a major cause of renal cell carcinoma and is often associated with late diagnosis and poor treatment outcomes. More evidence is emerging that genetic models can be used to predict the prognosis of KIRC. This study aimed to develop a model for predicting the overall survival of KIRC patients. Results We identified 333 differentially expressed genes (DEGs) between KIRC and normal tissues from the Gene Expression Omnibus (GEO) database. We randomly divided 591 cases from The Cancer Genome Atlas (TCGA) into training and internal testing sets. In the training set, we used univariate Cox regression analysis to retrieve the survival-related DEGs and futher used multivariate Cox regression with the LASSO penalty to identify potential prognostic genes. A seven-gene signature was identified that included APOLD1, C9orf66, G6PC, PPP1R1A, CNN1G, TIMP1, and TUBB2B. The seven-gene signature was evaluated in the training set, internal testing set, and external validation using data from the ICGC database. The Kaplan-Meier analysis showed that the high risk group had a significantly shorter overall survival time than the low risk group in the training, testing, and ICGC datasets. ROC analysis showed that the model had a high performance with an AUC of 0.738 in the training set, 0.706 in the internal testing set, and 0.656 in the ICGC external validation set. Conclusion Our findings show that a seven-gene signature can serve as an independent biomarker for predicting prognosis in KIRC patients.
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Gavrilovici C, Jiang Y, Kiroski I, Teskey GC, Rho JM, Nguyen MD. Postnatal Role of the Cytoskeleton in Adult Epileptogenesis. Cereb Cortex Commun 2020; 1:tgaa024. [PMID: 32864616 PMCID: PMC7446231 DOI: 10.1093/texcom/tgaa024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 06/08/2020] [Accepted: 06/11/2020] [Indexed: 02/07/2023] Open
Abstract
Mutations in cytoskeletal proteins can cause early infantile and childhood epilepsies by misplacing newly born neurons and altering neuronal connectivity. In the adult epileptic brain, cytoskeletal disruption is often viewed as being secondary to aberrant neuronal activity and/or death, and hence simply represents an epiphenomenon. Here, we review the emerging evidence collected in animal models and human studies implicating the cytoskeleton as a potential causative factor in adult epileptogenesis. Based on the emerging evidence, we propose that cytoskeletal disruption may be an important pathogenic mechanism in the mature epileptic brain.
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Affiliation(s)
- Cezar Gavrilovici
- Departments of Neurosciences & Pediatrics, University of California San Diego, Rady Children's Hospital San Diego, San Diego, CA 92123, USA
| | - Yulan Jiang
- Departments of Clinical Neurosciences, Cell Biology & Anatomy, and Biochemistry & Molecular Biology, Hotchkiss Brain Institute, Alberta Children Hospital Research Institute, University of Calgary, Calgary T2N 4N1, Canada
| | - Ivana Kiroski
- Departments of Clinical Neurosciences, Cell Biology & Anatomy, and Biochemistry & Molecular Biology, Hotchkiss Brain Institute, Alberta Children Hospital Research Institute, University of Calgary, Calgary T2N 4N1, Canada
| | - G Campbell Teskey
- Department of Cell Biology & Anatomy, Hotchkiss Brain Institute, Alberta Children Hospital Research Institute, University of Calgary, Calgary T2N 4N1, Canada
| | - Jong M Rho
- Departments of Neurosciences & Pediatrics, University of California San Diego, Rady Children's Hospital San Diego, San Diego, CA 92123, USA
| | - Minh Dang Nguyen
- Departments of Clinical Neurosciences, Cell Biology & Anatomy, and Biochemistry & Molecular Biology, Hotchkiss Brain Institute, Alberta Children Hospital Research Institute, University of Calgary, Calgary T2N 4N1, Canada
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45
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Moutin MJ, Bosc C, Peris L, Andrieux A. Tubulin post-translational modifications control neuronal development and functions. Dev Neurobiol 2020; 81:253-272. [PMID: 33325152 PMCID: PMC8246997 DOI: 10.1002/dneu.22774] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 05/26/2020] [Accepted: 07/14/2020] [Indexed: 12/22/2022]
Abstract
Microtubules (MTs) are an essential component of the neuronal cytoskeleton; they are involved in various aspects of neuron development, maintenance, and functions including polarization, synaptic plasticity, and transport. Neuronal MTs are highly heterogeneous due to the presence of multiple tubulin isotypes and extensive post‐translational modifications (PTMs). These PTMs—most notably detyrosination, acetylation, and polyglutamylation—have emerged as important regulators of the neuronal microtubule cytoskeleton. With this review, we summarize what is currently known about the impact of tubulin PTMs on microtubule dynamics, neuronal differentiation, plasticity, and transport as well as on brain function in normal and pathological conditions, in particular during neuro‐degeneration. The main therapeutic approaches to neuro‐diseases based on the modulation of tubulin PTMs are also summarized. Overall, the review indicates how tubulin PTMs can generate a large number of functionally specialized microtubule sub‐networks, each of which is crucial to specific neuronal features.
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Affiliation(s)
- Marie-Jo Moutin
- Grenoble Institut Neurosciences, University Grenoble Alpes, Inserm, U1216, CEA, CNRS, Grenoble, France
| | - Christophe Bosc
- Grenoble Institut Neurosciences, University Grenoble Alpes, Inserm, U1216, CEA, CNRS, Grenoble, France
| | - Leticia Peris
- Grenoble Institut Neurosciences, University Grenoble Alpes, Inserm, U1216, CEA, CNRS, Grenoble, France
| | - Annie Andrieux
- Grenoble Institut Neurosciences, University Grenoble Alpes, Inserm, U1216, CEA, CNRS, Grenoble, France
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46
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Garduno-Robles A, Alata M, Piazza V, Cortes C, Eguibar JR, Pantano S, Hernandez VH. MRI Features in a Rat Model of H-ABC Tubulinopathy. Front Neurosci 2020; 14:555. [PMID: 32581692 PMCID: PMC7284052 DOI: 10.3389/fnins.2020.00555] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 05/05/2020] [Indexed: 11/22/2022] Open
Abstract
Tubulinopathies are a group of recently described diseases characterized by mutations in the tubulin genes. Mutations in TUBB4A produce diseases such as dystonia type 4 (DYT4) and hypomyelination with atrophy of the basal ganglia and cerebellum (H-ABC), which are clinically diagnosed by magnetic resonance imaging (MRI). We propose the taiep rat as the first animal model for tubulinopathies. The spontaneous mutant suffers from a syndrome related to a central leukodystrophy and characterized by tremor, ataxia, immobility, epilepsy, and paralysis. The pathological signs presented by these rats and the morphological changes we found by our longitudinal MRI study are similar to those of patients with mutations in TUBB4A. The diffuse atrophy we found in brain, cerebellum and spinal cord is related to the changes detectable in many human tubulinopathies and in particular in H-ABC patients, where myelin degeneration at the level of putamen and cerebellum is a clinical trademark of the disease. We performed Tubb4a exon analysis to corroborate the genetic defect and formulated hypotheses about the effect of amino acid 302 change on protein physiology. Optical microscopy of taiep rat cerebella and spinal cord confirmed the optical density loss in white matter associated with myelin loss, despite the persistence of neural fibers.
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Affiliation(s)
- Angeles Garduno-Robles
- Departament of Chemical, Electronic and Biomedical Engineering, DCI, University of Guanajuato, Guanajuato, Mexico.,Center of Research in Optics, Leon, Mexico
| | | | | | - Carmen Cortes
- Institute of Physiology, Benemerita Universidad Autonoma de Puebla, Puebla, Mexico
| | - Jose R Eguibar
- Institute of Physiology, Benemerita Universidad Autonoma de Puebla, Puebla, Mexico.,Research Office of the Vice-rectory of Research and Postgraduate Studies, Benemerita Universidad Autonoma de Puebla, Puebla, Mexico
| | - Sergio Pantano
- Group of Biomolecular Simulations, Institut Pasteur de Montevideo, Montevideo, Uruguay
| | - Victor H Hernandez
- Departament of Chemical, Electronic and Biomedical Engineering, DCI, University of Guanajuato, Guanajuato, Mexico
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47
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Jossin Y. Molecular mechanisms of cell polarity in a range of model systems and in migrating neurons. Mol Cell Neurosci 2020; 106:103503. [PMID: 32485296 DOI: 10.1016/j.mcn.2020.103503] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 04/20/2020] [Accepted: 05/23/2020] [Indexed: 01/09/2023] Open
Abstract
Cell polarity is defined as the asymmetric distribution of cellular components along an axis. Most cells, from the simplest single-cell organisms to highly specialized mammalian cells, are polarized and use similar mechanisms to generate and maintain polarity. Cell polarity is important for cells to migrate, form tissues, and coordinate activities. During development of the mammalian cerebral cortex, cell polarity is essential for neurogenesis and for the migration of newborn but as-yet undifferentiated neurons. These oriented migrations include both the radial migration of excitatory projection neurons and the tangential migration of inhibitory interneurons. In this review, I will first describe the development of the cerebral cortex, as revealed at the cellular level. I will then define the core molecular mechanisms - the Par/Crb/Scrib polarity complexes, small GTPases, the actin and microtubule cytoskeletons, and phosphoinositides/PI3K signaling - that are required for asymmetric cell division, apico-basal and front-rear polarity in model systems, including C elegans zygote, Drosophila embryos and cultured mammalian cells. As I go through each core mechanism I will explain what is known about its importance in radial and tangential migration in the developing mammalian cerebral cortex.
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Affiliation(s)
- Yves Jossin
- Laboratory of Mammalian Development & Cell Biology, Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium.
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48
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Sferra A, Petrini S, Bellacchio E, Nicita F, Scibelli F, Dentici ML, Alfieri P, Cestra G, Bertini ES, Zanni G. TUBB Variants Underlying Different Phenotypes Result in Altered Vesicle Trafficking and Microtubule Dynamics. Int J Mol Sci 2020; 21:ijms21041385. [PMID: 32085672 PMCID: PMC7073044 DOI: 10.3390/ijms21041385] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 02/13/2020] [Accepted: 02/14/2020] [Indexed: 11/26/2022] Open
Abstract
Tubulinopathies are rare neurological disorders caused by alterations in tubulin structure and function, giving rise to a wide range of brain abnormalities involving neuronal proliferation, migration, differentiation and axon guidance. TUBB is one of the ten β-tubulin encoding genes present in the human genome and is broadly expressed in the developing central nervous system and the skin. Mutations in TUBB are responsible for two distinct pathological conditions: the first is characterized by microcephaly and complex structural brain malformations and the second, also known as “circumferential skin creases Kunze type” (CSC-KT), is associated to neurological features, excess skin folding and growth retardation. We used a combination of immunocytochemical and cellular approaches to explore, on patients’ derived fibroblasts, the functional consequences of two TUBB variants: the novel mutation (p.N52S), associated with basal ganglia and cerebellar dysgenesis, and the previously reported variant (p.M73T), linked to microcephaly, corpus callosum agenesis and CSC-KT skin phenotype. Our results demonstrate that these variants impair microtubule (MT) function and dynamics. Most importantly, our studies show an altered epidermal growth factor (EGF) and transferrin (Tf) intracellular vesicle trafficking in both patients’ fibroblasts, suggesting a specific role of TUBB in MT-dependent vesicular transport.
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Affiliation(s)
- Antonella Sferra
- Unit of Neuromuscular and Neurodegenerative Disorders, Department Neurosciences, Bambino Gesù Children’s Hospital, IRCCS, 00146 Rome, Italy; (F.N.); (E.S.B.)
- Correspondence: (A.S.); (G.Z.)
| | - Stefania Petrini
- Confocal Microscopy Core Facility, Research Laboratories, Ospedale Pediatrico Bambino Gesù, 00146 Rome, Italy;
| | - Emanuele Bellacchio
- Department of Research Laboratories, Bambino Gesù Children’s Hospital, 00146 Rome, Italy;
| | - Francesco Nicita
- Unit of Neuromuscular and Neurodegenerative Disorders, Department Neurosciences, Bambino Gesù Children’s Hospital, IRCCS, 00146 Rome, Italy; (F.N.); (E.S.B.)
| | - Francesco Scibelli
- Unit of Child Neuropsychiatry, Department of Neurosciences, Bambino Gesù Children’s Hospital, 00165 Rome, Italy; (F.S.); (P.A.)
| | - Maria Lisa Dentici
- Unit of Medical Genetics, Bambino Gesù Children’s Hospital, IRCCS, 00146 Rome, Italy;
| | - Paolo Alfieri
- Unit of Child Neuropsychiatry, Department of Neurosciences, Bambino Gesù Children’s Hospital, 00165 Rome, Italy; (F.S.); (P.A.)
| | - Gianluca Cestra
- Institute of Molecular Biology and Pathology (IBPM), National Research Council (CNR) and University of Rome “Sapienza”, Department of Biology and Biotechnology, 00185 Rome, Italy;
| | - Enrico Silvio Bertini
- Unit of Neuromuscular and Neurodegenerative Disorders, Department Neurosciences, Bambino Gesù Children’s Hospital, IRCCS, 00146 Rome, Italy; (F.N.); (E.S.B.)
| | - Ginevra Zanni
- Unit of Neuromuscular and Neurodegenerative Disorders, Department Neurosciences, Bambino Gesù Children’s Hospital, IRCCS, 00146 Rome, Italy; (F.N.); (E.S.B.)
- Correspondence: (A.S.); (G.Z.)
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Trushina NI, Mulkidjanian AY, Brandt R. The microtubule skeleton and the evolution of neuronal complexity in vertebrates. Biol Chem 2020; 400:1163-1179. [PMID: 31116700 DOI: 10.1515/hsz-2019-0149] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 04/17/2019] [Indexed: 12/21/2022]
Abstract
The evolution of a highly developed nervous system is mirrored by the ability of individual neurons to develop increased morphological complexity. As microtubules (MTs) are crucially involved in neuronal development, we tested the hypothesis that the evolution of complexity is driven by an increasing capacity of the MT system for regulated molecular interactions as it may be implemented by a higher number of molecular players and a greater ability of the individual molecules to interact. We performed bioinformatics analysis on different classes of components of the vertebrate neuronal MT cytoskeleton. We show that the number of orthologs of tubulin structure proteins, MT-binding proteins and tubulin-sequestering proteins expanded during vertebrate evolution. We observed that protein diversity of MT-binding and tubulin-sequestering proteins increased by alternative splicing. In addition, we found that regions of the MT-binding protein tau and MAP6 displayed a clear increase in disorder extent during evolution. The data provide evidence that vertebrate evolution is paralleled by gene expansions, changes in alternative splicing and evolution of coding sequences of components of the MT system. The results suggest that in particular evolutionary changes in tubulin-structure proteins, MT-binding proteins and tubulin-sequestering proteins were prominent drivers for the development of increased neuronal complexity.
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Affiliation(s)
- Nataliya I Trushina
- Department of Neurobiology, University of Osnabrück, Barbarastraße 11, D-49076 Osnabrück, Germany
| | - Armen Y Mulkidjanian
- Department of Physics, University of Osnabrück, Barbarastraße 7, D-49076 Osnabrück, Germany.,A.N. Belozersky Institute of Physico-Chemical Biology and School of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow 119991, Russia
| | - Roland Brandt
- Department of Neurobiology, University of Osnabrück, Barbarastraße 11, D-49076 Osnabrück, Germany.,Center for Cellular Nanoanalytics, University of Osnabrück, Barbarastraße 11, D-49076 Osnabrück, Germany.,Institute of Cognitive Science, University of Osnabrück, Barbarastraße 11, D-49076 Osnabrück, Germany
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50
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TMX2 Is a Crucial Regulator of Cellular Redox State, and Its Dysfunction Causes Severe Brain Developmental Abnormalities. Am J Hum Genet 2019; 105:1126-1147. [PMID: 31735293 DOI: 10.1016/j.ajhg.2019.10.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 10/11/2019] [Indexed: 02/07/2023] Open
Abstract
The redox state of the neural progenitors regulates physiological processes such as neuronal differentiation and dendritic and axonal growth. The relevance of endoplasmic reticulum (ER)-associated oxidoreductases in these processes is largely unexplored. We describe a severe neurological disorder caused by bi-allelic loss-of-function variants in thioredoxin (TRX)-related transmembrane-2 (TMX2); these variants were detected by exome sequencing in 14 affected individuals from ten unrelated families presenting with congenital microcephaly, cortical polymicrogyria, and other migration disorders. TMX2 encodes one of the five TMX proteins of the protein disulfide isomerase family, hitherto not linked to human developmental brain disease. Our mechanistic studies on protein function show that TMX2 localizes to the ER mitochondria-associated membranes (MAMs), is involved in posttranslational modification and protein folding, and undergoes physical interaction with the MAM-associated and ER folding chaperone calnexin and ER calcium pump SERCA2. These interactions are functionally relevant because TMX2-deficient fibroblasts show decreased mitochondrial respiratory reserve capacity and compensatory increased glycolytic activity. Intriguingly, under basal conditions TMX2 occurs in both reduced and oxidized monomeric form, while it forms a stable dimer under treatment with hydrogen peroxide, recently recognized as a signaling molecule in neural morphogenesis and axonal pathfinding. Exogenous expression of the pathogenic TMX2 variants or of variants with an in vitro mutagenized TRX domain induces a constitutive TMX2 polymerization, mimicking an increased oxidative state. Altogether these data uncover TMX2 as a sensor in the MAM-regulated redox signaling pathway and identify it as a key adaptive regulator of neuronal proliferation, migration, and organization in the developing brain.
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