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Mehmood A, Shah S, Guo RY, Haider A, Shi M, Ali H, Ali I, Ullah R, Li B. Methyl-CpG-Binding Protein 2 Emerges as a Central Player in Multiple Sclerosis and Neuromyelitis Optica Spectrum Disorders. Cell Mol Neurobiol 2023; 43:4071-4101. [PMID: 37955798 DOI: 10.1007/s10571-023-01432-7] [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: 08/27/2023] [Accepted: 10/27/2023] [Indexed: 11/14/2023]
Abstract
MECP2 and its product methyl-CpG binding protein 2 (MeCP2) are associated with multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOSD), which are inflammatory, autoimmune, and demyelinating disorders of the central nervous system (CNS). However, the mechanisms and pathways regulated by MeCP2 in immune activation in favor of MS and NMOSD are not fully understood. We summarize findings that use the binding properties of MeCP2 to identify its targets, particularly the genes recognized by MeCP2 and associated with several neurological disorders. MeCP2 regulates gene expression in neurons, immune cells and during development by modulating various mechanisms and pathways. Dysregulation of the MeCP2 signaling pathway has been associated with several disorders, including neurological and autoimmune diseases. A thorough understanding of the molecular mechanisms underlying MeCP2 function can provide new therapeutic strategies for these conditions. The nervous system is the primary system affected in MeCP2-associated disorders, and other systems may also contribute to MeCP2 action through its target genes. MeCP2 signaling pathways provide promise as potential therapeutic targets in progressive MS and NMOSD. MeCP2 not only increases susceptibility and induces anti-inflammatory responses in immune sites but also leads to a chronic increase in pro-inflammatory cytokines gene expression (IFN-γ, TNF-α, and IL-1β) and downregulates the genes involved in immune regulation (IL-10, FoxP3, and CX3CR1). MeCP2 may modulate similar mechanisms in different pathologies and suggest that treatments for MS and NMOSD disorders may be effective in treating related disorders. MeCP2 regulates gene expression in MS and NMOSD. However, dysregulation of the MeCP2 signaling pathway is implicated in these disorders. MeCP2 plays a role as a therapeutic target for MS and NMOSD and provides pathways and mechanisms that are modulated by MeCP2 in the regulation of gene expression.
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Affiliation(s)
- Arshad Mehmood
- Department of Neurology, The Second Hospital of Hebei Medical University, Shijiazhuang, 050000, Hebei, People's Republic of China
- Key Laboratory of Neurology of Hebei Province, Shijiazhuang, 050000, Hebei, People's Republic of China
| | - Suleman Shah
- Department of Cell Biology and Genetics, School of Basic Medical Sciences, Health Science Center, Shenzhen University, Shenzhen, China
| | - Ruo-Yi Guo
- Department of Neurology, The Second Hospital of Hebei Medical University, Shijiazhuang, 050000, Hebei, People's Republic of China
- Key Laboratory of Neurology of Hebei Province, Shijiazhuang, 050000, Hebei, People's Republic of China
| | - Arsalan Haider
- Key Lab of Health Psychology, Institute of Psychology, University of Chinese Academy of Sciences, Beijing, China
| | - Mengya Shi
- Department of Neurology, The Second Hospital of Hebei Medical University, Shijiazhuang, 050000, Hebei, People's Republic of China
- Key Laboratory of Neurology of Hebei Province, Shijiazhuang, 050000, Hebei, People's Republic of China
| | - Hamid Ali
- Department of Biosciences, COMSATS University Islamabad, Park Road Tarlai Kalan, Islamabad, 44000, Pakistan
| | - Ijaz Ali
- Centre for Applied Mathematics and Bioinformatics, Gulf University for Science and Technology, Hawally, 32093, Kuwait
| | - Riaz Ullah
- Medicinal Aromatic and Poisonous Plants Research Center, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia
| | - Bin Li
- Department of Neurology, The Second Hospital of Hebei Medical University, Shijiazhuang, 050000, Hebei, People's Republic of China.
- Key Laboratory of Neurology of Hebei Province, Shijiazhuang, 050000, Hebei, People's Republic of China.
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Affiliation(s)
- Ryan C Hunt
- From the Division of Plasma Protein Therapeutics, Office of Tissues and Advanced Therapies, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, MD
| | - Chava Kimchi-Sarfaty
- From the Division of Plasma Protein Therapeutics, Office of Tissues and Advanced Therapies, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, MD
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Sarkar A, Panati K, Narala VR. Code inside the codon: The role of synonymous mutations in regulating splicing machinery and its impact on disease. MUTATION RESEARCH. REVIEWS IN MUTATION RESEARCH 2022; 790:108444. [PMID: 36307006 DOI: 10.1016/j.mrrev.2022.108444] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 10/10/2022] [Accepted: 10/21/2022] [Indexed: 11/06/2022]
Abstract
In eukaryotes, precise pre-mRNA processing, including alternative splicing, is essential to carry out the intricate protein translation process. Both point mutations (that alter the translated protein sequence) and synonymous mutations (that do not alter the translated protein sequence) are capable of affecting the splicing process. Synonymous mutations are known to affect gene expression via altering mRNA stability, mRNA secondary structure, splicing processes, and translational kinetics. In higher eukaryotes, precise splicing is regulated by three weakly conserved cis-elements, 5' and 3' splice sites and the branch site. Many other cis-acting elements (exonic/intronic splicing enhancers and silencers) and trans-acting splicing factors (serine and arginine-rich proteins and heterogeneous nuclear ribonucleoproteins) have also been found to enhance or suppress the splicing process. The appearance of synonymous mutations in cis-acting elements can alter the splicing process by changing the binding pattern of splicing factors to exonic splicing enhancers or silencer motifs. This results in exon skipping, intron retention, and various other forms of alternative splicing, eventually leading to the emergence of a wide range of diseases. The focus of this review is to elucidate the role of synonymous mutations and their impact on abnormal splicing mechanisms. Further, this study highlights the function of synonymous mutation in mediating abnormal splicing in cancer and development of X-linked, and autosomal inherited diseases.
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Affiliation(s)
- Avik Sarkar
- Department of Zoology, Vidyasagar University, Midnapore, West Bengal 721102, India
| | - Kalpana Panati
- Department of Biotechnology, Government College for Men, Kadapa 516004, India
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Fu Y, Huang S, Gao X, Han M, Wang G, Kang D, Yuan Y, Dai P. Analysis of the genotype–phenotype correlation of MYO15A variants in Chinese non-syndromic hearing loss patients. BMC Med Genomics 2022; 15:71. [PMID: 35346193 PMCID: PMC8962197 DOI: 10.1186/s12920-022-01201-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 02/28/2022] [Indexed: 11/10/2022] Open
Abstract
Abstract
Background
Mutations in the MYO15A gene are a widely recognized cause of autosomal recessive non-syndromic sensorineural hearing loss (NSHL) globally. Here, we examined the role and the genotype–phenotype correlation of MYO15A variants in a cohort of Chinese NSHL cases.
Methods
Eighty-one cases with evidenced MYO15A variants from the 2263 Chinese NSHL cases, who underwent next-generation sequencing (NGS), were enrolled in the study. We investigated the association of MYO15A variants with the severity, progression and age of onset of hearing loss, as well as compared it to the previous reports in different nationalities. The cases were divided into groups according to the number of truncating variants: 2 truncating, 1 truncating and 1 non-truncating, 2 non-truncating variants, and compared the severity of HL among the groups.
Results
MYO15A accounted for 3.58% (81/2263) of all NSHL cases. We analyzed 81 MYO15A-related NSHL cases, 73 of whom were with congenital bilateral, symmetric or severe-to-profound hearing loss (HL), however, 2 of them had a postlingual, asymmetric, mild or moderate HL. There were 102 variants identified in all MYO15A structural domains, 76.47% (78/102) of whom were novel. The most common types of detected variants were missense (44/102, 43.14%), followed by frameshift (27/102, 26.47%), nonsense (14/102, 13.72%), splice site (10/102, 9.80%), in frame (4/102, 3.92%), non-coding (2/102, 1.96%) and synonymous (1/102, 0.98%). The most recurrent variant c.10245_10247delCTC was detected in 12 cases. We observed that the MYO15A variants, located in its N-terminal, motor and FERM domains, led to partial deafness with better residual hearing at low frequencies. There were 34 cases with biallelic truncating variants, 37 cases with monoallelic truncating variants, and 13 cases with biallelic non-truncating variants. The biallelic non-truncating variants group had the least number of cases (12/81), and most of them (10/12) were with profound NSHL.
Conclusions
MYO15A is a major gene responsible for NSHL in China. Cases with MYO15A variants mostly showed early-onset, symmetric, severe-to-profound hearing loss. This study is by far the largest focused on the evaluation of the genotype–phenotype correlations among the variants in the MYO15A gene and its implication in the outcome of NSHL. The biallelic non-truncating MYO15A variants commonly caused profound HL, and the cases with one or two truncating MYO15A variants tended to increase the risk of HL. Nevertheless, further investigations are needed to clarify the causes for the variable severities and progression rates of hearing loss and the detected MYO15A variants in these cases.
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Abrahams L, Savisaar R, Mordstein C, Young B, Kudla G, Hurst LD. Evidence in disease and non-disease contexts that nonsense mutations cause altered splicing via motif disruption. Nucleic Acids Res 2021; 49:9665-9685. [PMID: 34469537 PMCID: PMC8464065 DOI: 10.1093/nar/gkab750] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 08/17/2021] [Accepted: 08/19/2021] [Indexed: 12/21/2022] Open
Abstract
Transcripts containing premature termination codons (PTCs) can be subject to nonsense-associated alternative splicing (NAS). Two models have been evoked to explain this, scanning and splice motif disruption. The latter postulates that exonic cis motifs, such as exonic splice enhancers (ESEs), are disrupted by nonsense mutations. We employ genome-wide transcriptomic and k-mer enrichment methods to scrutinize this model. First, we show that ESEs are prone to disruptive nonsense mutations owing to their purine richness and paucity of TGA, TAA and TAG. The motif model correctly predicts that NAS rates should be low (we estimate 5–30%) and approximately in line with estimates for the rate at which random point mutations disrupt splicing (8–20%). Further, we find that, as expected, NAS-associated PTCs are predictable from nucleotide-based machine learning approaches to predict splice disruption and, at least for pathogenic variants, are enriched in ESEs. Finally, we find that both in and out of frame mutations to TAA, TGA or TAG are associated with exon skipping. While a higher relative frequency of such skip-inducing mutations in-frame than out of frame lends some credence to the scanning model, these results reinforce the importance of considering splice motif modulation to understand the etiology of PTC-associated disease.
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Affiliation(s)
- Liam Abrahams
- The Milner Centre for Evolution, Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK
| | - Rosina Savisaar
- The Milner Centre for Evolution, Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK.,Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Christine Mordstein
- The Milner Centre for Evolution, Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK.,MRC Human Genetics Unit, The University of Edinburgh, Crewe Road, Edinburgh EH4 2XU, UK.,Aarhus University, Department of Molecular Biology and Genetics, C F Møllers Allé 3, 8000 Aarhus, Denmark
| | - Bethan Young
- MRC Human Genetics Unit, The University of Edinburgh, Crewe Road, Edinburgh EH4 2XU, UK
| | - Grzegorz Kudla
- MRC Human Genetics Unit, The University of Edinburgh, Crewe Road, Edinburgh EH4 2XU, UK
| | - Laurence D Hurst
- The Milner Centre for Evolution, Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK
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Good KV, Vincent JB, Ausió J. MeCP2: The Genetic Driver of Rett Syndrome Epigenetics. Front Genet 2021; 12:620859. [PMID: 33552148 PMCID: PMC7859524 DOI: 10.3389/fgene.2021.620859] [Citation(s) in RCA: 56] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 01/05/2021] [Indexed: 12/24/2022] Open
Abstract
Mutations in methyl CpG binding protein 2 (MeCP2) are the major cause of Rett syndrome (RTT), a rare neurodevelopmental disorder with a notable period of developmental regression following apparently normal initial development. Such MeCP2 alterations often result in changes to DNA binding and chromatin clustering ability, and in the stability of this protein. Among other functions, MeCP2 binds to methylated genomic DNA, which represents an important epigenetic mark with broad physiological implications, including neuronal development. In this review, we will summarize the genetic foundations behind RTT, and the variable degrees of protein stability exhibited by MeCP2 and its mutated versions. Also, past and emerging relationships that MeCP2 has with mRNA splicing, miRNA processing, and other non-coding RNAs (ncRNA) will be explored, and we suggest that these molecules could be missing links in understanding the epigenetic consequences incurred from genetic ablation of this important chromatin modifier. Importantly, although MeCP2 is highly expressed in the brain, where it has been most extensively studied, the role of this protein and its alterations in other tissues cannot be ignored and will also be discussed. Finally, the additional complexity to RTT pathology introduced by structural and functional implications of the two MeCP2 isoforms (MeCP2-E1 and MeCP2-E2) will be described. Epigenetic therapeutics are gaining clinical popularity, yet treatment for Rett syndrome is more complicated than would be anticipated for a purely epigenetic disorder, which should be taken into account in future clinical contexts.
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Affiliation(s)
- Katrina V. Good
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada
| | - John B. Vincent
- Molecular Neuropsychiatry & Development (MiND) Lab, Centre for Addiction and Mental Health, Campbell Family Mental Health Research Institute, Toronto, ON, Canada
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada
- Department of Psychiatry, University of Toronto, Toronto, ON, Canada
| | - Juan Ausió
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada
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Khalili Alashti S, Fallahi J, Jokar A, Fardaei M. CRISPR/Cas9 knock-in toward creating a Rett syndrome cell model with a synonymous mutation in the MECP2 gene. J Gene Med 2020; 22:e3258. [PMID: 32761967 DOI: 10.1002/jgm.3258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Revised: 07/29/2020] [Accepted: 07/29/2020] [Indexed: 11/07/2022] Open
Abstract
BACKGROUND Rett syndrome is an X-linked dominant neurodevelopmental disease caused by mutation in the methyl-CpG-binding protein 2 (MECP2) gene. This gene encodes a methylated DNA-binding protein, which acts as a transcriptional regulatory factor. The present study aimed to establish a cell model of Rett syndrome with the MECP2 synonymous mutation c.354G>T (p.Gly118Gly). In addition, the molecular mechanism of pathogenesis of this mutation was also investigated. METHODS To create a cell line containing the synonymous variant in MECP2 locus, the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9-mediated homology-directed repair precise gene editing method was used. In addition, employing the synthesis of cDNA, the effect of this variant on splicing was investigated. RESULTS Using this model and molecular analysis, we found that the c.354G>T synonymous variant created a novel 5' cryptic splice donor site within the exon 3 of MECP2 gene, which resulted in the deletion of 25 nucleotides at the 3' end of exon 3 and presumably protein truncation. CONCLUSIONS The results of the present study show that an apparently neutral synonymous polymorphism, which may be commonly classified as non-pathogenic, may indeed lead to the creation of an aberrant splice site, thereby resulting in disease.
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Affiliation(s)
| | - Jafar Fallahi
- Department of Molecular Medicine, School of Advanced Medical Sciences and Technologies, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Arezoo Jokar
- Department of Medical Biotechnology, School of Paramedical Sciences, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Majid Fardaei
- Department of Medical Genetics, Shiraz University of Medical Sciences, Shiraz, Iran.,Comprehensive Medical Genetic Center, Shiraz University of Medical Sciences, Shiraz, Iran
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8
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Khalili Alashti S, Fallahi J, Mohammadi S, Dehghanian F, Farbood Z, Masoudi M, Poorang S, Jokar A, Fardaei M. Two novel mutations in the MECP2 gene in patients with Rett syndrome. Gene 2020; 732:144337. [DOI: 10.1016/j.gene.2020.144337] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 12/04/2019] [Accepted: 01/06/2020] [Indexed: 12/28/2022]
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9
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Jayasinghe RG, Cao S, Gao Q, Wendl MC, Vo NS, Reynolds SM, Zhao Y, Climente-González H, Chai S, Wang F, Varghese R, Huang M, Liang WW, Wyczalkowski MA, Sengupta S, Li Z, Payne SH, Fenyö D, Miner JH, Walter MJ, Vincent B, Eyras E, Chen K, Shmulevich I, Chen F, Ding L. Systematic Analysis of Splice-Site-Creating Mutations in Cancer. Cell Rep 2019; 23:270-281.e3. [PMID: 29617666 PMCID: PMC6055527 DOI: 10.1016/j.celrep.2018.03.052] [Citation(s) in RCA: 144] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 02/21/2018] [Accepted: 03/13/2018] [Indexed: 12/31/2022] Open
Abstract
For the past decade, cancer genomic studies have focused on mutations leading to splice-site disruption, overlooking those having splice-creating potential. Here, we applied a bioinformatic tool, MiSplice, for the large-scale discovery of splice-site-creating mutations (SCMs) across 8,656 TCGA tumors. We report 1,964 originally mis-annotated mutations having clear evidence of creating alternative splice junctions. TP53 and GATA3 have 26 and 18 SCMs, respectively, and ATRX has 5 from lower-grade gliomas. Mutations in 11 genes, including PARP1, BRCA1, and BAP1, were experimentally validated for splice-site-creating function. Notably, we found that neoantigens induced by SCMs are likely several folds more immunogenic compared to missense mutations, exemplified by the recurrent GATA3 SCM. Further, high expression of PD-1 and PD-L1 was observed in tumors with SCMs, suggesting candidates for immune blockade therapy. Our work highlights the importance of integrating DNA and RNA data for understanding the functional and the clinical implications of mutations in human diseases.
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Affiliation(s)
- Reyka G Jayasinghe
- Department of Medicine, Washington University in St. Louis, St. Louis, MO 63110, USA; McDonnell Genome Institute, Washington University in St. Louis, St. Louis, MO 63108, USA; Division of Oncology, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Song Cao
- Department of Medicine, Washington University in St. Louis, St. Louis, MO 63110, USA; McDonnell Genome Institute, Washington University in St. Louis, St. Louis, MO 63108, USA; Division of Oncology, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Qingsong Gao
- Department of Medicine, Washington University in St. Louis, St. Louis, MO 63110, USA; McDonnell Genome Institute, Washington University in St. Louis, St. Louis, MO 63108, USA; Division of Oncology, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Michael C Wendl
- McDonnell Genome Institute, Washington University in St. Louis, St. Louis, MO 63108, USA; Division of Oncology, Washington University in St. Louis, St. Louis, MO 63110, USA; Department of Genetics, Washington University in St. Louis, St. Louis, MO 63110, USA; Department of Mathematics, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Nam Sy Vo
- Department of Bioinformatics and Computational Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | | | - Yanyan Zhao
- Department of Medicine, Washington University in St. Louis, St. Louis, MO 63110, USA; McDonnell Genome Institute, Washington University in St. Louis, St. Louis, MO 63108, USA; Division of Oncology, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Héctor Climente-González
- Institut Curie, 75248 Paris Cedex, France; MINES ParisTech, PSL-Research University, CBIO-Centre for Computational Biology, 77300 Fontainebleau, France; INSERM U900, 75248 Paris Cedex, France
| | - Shengjie Chai
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Curriculum in Bioinformatics and Computational Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Fang Wang
- Department of Bioinformatics and Computational Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Rajees Varghese
- Department of Medicine, Washington University in St. Louis, St. Louis, MO 63110, USA; Division of Nephrology, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Mo Huang
- Department of Medicine, Washington University in St. Louis, St. Louis, MO 63110, USA; McDonnell Genome Institute, Washington University in St. Louis, St. Louis, MO 63108, USA
| | - Wen-Wei Liang
- Department of Medicine, Washington University in St. Louis, St. Louis, MO 63110, USA; McDonnell Genome Institute, Washington University in St. Louis, St. Louis, MO 63108, USA; Division of Oncology, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Matthew A Wyczalkowski
- Department of Medicine, Washington University in St. Louis, St. Louis, MO 63110, USA; McDonnell Genome Institute, Washington University in St. Louis, St. Louis, MO 63108, USA; Division of Oncology, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Sohini Sengupta
- Department of Medicine, Washington University in St. Louis, St. Louis, MO 63110, USA; McDonnell Genome Institute, Washington University in St. Louis, St. Louis, MO 63108, USA; Division of Oncology, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Zhi Li
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA; Institute for Systems Genetics, New York University School of Medicine, New York, NY 10016, USA
| | - Samuel H Payne
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, USA
| | - David Fenyö
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA; Institute for Systems Genetics, New York University School of Medicine, New York, NY 10016, USA
| | - Jeffrey H Miner
- Department of Medicine, Washington University in St. Louis, St. Louis, MO 63110, USA; Division of Nephrology, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Matthew J Walter
- Department of Medicine, Washington University in St. Louis, St. Louis, MO 63110, USA; Siteman Cancer Center, Washington University in St. Louis, St. Louis, MO 63110, USA
| | | | - Benjamin Vincent
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Curriculum in Bioinformatics and Computational Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Eduardo Eyras
- Catalan Institution of Research and Advanced Studies (ICREA), 08010 Barcelona, Spain; Computational RNA Biology Group, Pompeu Fabra University (UPF), 08003 Barcelona, Spain
| | - Ken Chen
- Department of Bioinformatics and Computational Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | | | - Feng Chen
- Department of Medicine, Washington University in St. Louis, St. Louis, MO 63110, USA; Division of Nephrology, Washington University in St. Louis, St. Louis, MO 63110, USA.
| | - Li Ding
- Department of Medicine, Washington University in St. Louis, St. Louis, MO 63110, USA; McDonnell Genome Institute, Washington University in St. Louis, St. Louis, MO 63108, USA; Division of Oncology, Washington University in St. Louis, St. Louis, MO 63110, USA; Department of Genetics, Washington University in St. Louis, St. Louis, MO 63110, USA; Siteman Cancer Center, Washington University in St. Louis, St. Louis, MO 63110, USA.
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10
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Understanding human DNA variants affecting pre-mRNA splicing in the NGS era. ADVANCES IN GENETICS 2019; 103:39-90. [PMID: 30904096 DOI: 10.1016/bs.adgen.2018.09.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Pre-mRNA splicing, an essential step in eukaryotic gene expression, relies on recognition of short sequences on the primary transcript intron ends and takes place along transcription by RNA polymerase II. Exonic and intronic auxiliary elements may modify the strength of exon definition and intron recognition. Splicing DNA variants (SV) have been associated with human genetic diseases at canonical intron sites, as well as exonic substitutions putatively classified as nonsense, missense or synonymous variants. Their effects on mRNA may be modulated by cryptic splice sites associated to the SV allele, comprehending exon skipping or shortening, and partial or complete intron retention. As splicing mRNA outputs result from combinatorial effects of both intrinsic and extrinsic factors, in vitro functional assays supported by computational analyses are recommended to assist SV pathogenicity assessment for human Mendelian inheritance diseases. The increasing use of next-generating sequencing (NGS) targeting full genomic gene sequence has raised awareness of the relevance of deep intronic SV in genetic diseases and inclusion of pseudo-exons into mRNA. Finally, we take advantage of recent advances in sequencing and computational technologies to analyze alternative splicing in cancer. We explore the Catalog of Somatic Mutations in Cancer (COSMIC) to describe the proportion of splice-site mutations in cis and trans regulatory elements. Genomic data from large cohorts of different cancer types are increasingly available, in addition to repositories of normal and somatic genetic variations. These are likely to bring new insights to understanding the genetic control of alternative splicing by mapping splicing quantitative trait loci in tumors.
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11
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Sheikh TI, de Paz AM, Akhtar S, Ausió J, Vincent JB. MeCP2_E1 N-terminal modifications affect its degradation rate and are disrupted by the Ala2Val Rett mutation. Hum Mol Genet 2018; 26:4132-4141. [PMID: 28973632 DOI: 10.1093/hmg/ddx300] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Accepted: 07/24/2017] [Indexed: 11/14/2022] Open
Abstract
Methyl CpG-binding protein 2 (MeCP2), the mutated protein in Rett syndrome (RTT), is a crucial chromatin-modifying and gene-regulatory protein that has two main isoforms (MeCP2_E1 and MeCP2_ E2) due to the alternative splicing and switching between translation start codons in exons one and two. Functionally, these two isoforms appear to be virtually identical; however, evidence suggests that only MeCP2_E1 is relevant to RTT, including a single RTT missense mutation in exon 1, Ala2Val. Here, we show that N-terminal co- and post-translational modifications differ for MeCP2_E1 and MeCP2_E1-Ala2Val, which result in different protein degradation rates in vitro. We report complete N-methionine excision (NME) for MeCP2_E1 and evidence of excision of multiple alanine residues from the N-terminal polyalanine stretch. For MeCP2_E1-Ala2Val, we observed only partial NME and N-acetylation (NA) of either methionine or valine. The localization of MeCP2_E1 and co-localization with chromatin appear to be unaffected by the Ala2Val mutation. However, a higher proteasomal degradation rate was observed for MeCP2_E1-Ala2Val compared with that for wild type MeCP2_E1. Thus, the etiopathology of Ala2Val is likely due to a reduced bio-availability of MeCP2 because of the faster degradation rate of the unmodified defective protein. Our data on the effects of the Ala2Val mutation on N-terminal modifications of MeCP2 may be applicable to Ala2Val mutations in other disease genes for which no etiopathological mechanism has been established.
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Affiliation(s)
- Taimoor I Sheikh
- Molecular Neuropsychiatry & Development (MiND) Lab, Brain Science Division, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON M5T 1R8, Canada.,Institute of Medical Science, University of Toronto, Toronto, ON M5S 1A8, Canada
| | | | - Shamim Akhtar
- University of Engineering and Technology Taxila, Taxila, Punjab 47080, Pakistan
| | - Juan Ausió
- Department of Biochemistry and Microbiology, University of Victoria, BC V8P 5C2, Canada
| | - John B Vincent
- Molecular Neuropsychiatry & Development (MiND) Lab, Brain Science Division, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON M5T 1R8, Canada.,Institute of Medical Science, University of Toronto, Toronto, ON M5S 1A8, Canada.,Department of Psychiatry, University of Toronto, Toronto, ON M5T 1R8, Canada
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12
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Sheikh TI, Harripaul R, Ayub M, Vincent JB. MeCP2 AT-Hook1 mutations in patients with intellectual disability and/or schizophrenia disrupt DNA binding and chromatin compaction in vitro. Hum Mutat 2018; 39:717-728. [DOI: 10.1002/humu.23409] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 01/10/2018] [Accepted: 02/07/2018] [Indexed: 01/29/2023]
Affiliation(s)
- Taimoor I. Sheikh
- Molecular Neuropsychiatry & Development (MiND) Lab; Campbell Family Mental Health Research Institute; Centre for Addiction and Mental Health; Toronto Ontario Canada
- Institute of Medical Science; University of Toronto; Toronto Ontario Canada
| | - Ricardo Harripaul
- Molecular Neuropsychiatry & Development (MiND) Lab; Campbell Family Mental Health Research Institute; Centre for Addiction and Mental Health; Toronto Ontario Canada
- Institute of Medical Science; University of Toronto; Toronto Ontario Canada
| | - Muhammad Ayub
- Lahore Institute of Research & Development; Lahore Pakistan
- Department of Psychiatry; Queen's University; Kingston Ontario Canada
| | - John B. Vincent
- Molecular Neuropsychiatry & Development (MiND) Lab; Campbell Family Mental Health Research Institute; Centre for Addiction and Mental Health; Toronto Ontario Canada
- Institute of Medical Science; University of Toronto; Toronto Ontario Canada
- Department of Psychiatry; University of Toronto; Toronto Ontario Canada
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13
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Eilbeck K, Quinlan A, Yandell M. Settling the score: variant prioritization and Mendelian disease. Nat Rev Genet 2017; 18:599-612. [PMID: 28804138 PMCID: PMC5935497 DOI: 10.1038/nrg.2017.52] [Citation(s) in RCA: 150] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
When investigating Mendelian disease using exome or genome sequencing, distinguishing disease-causing genetic variants from the multitude of candidate variants is a complex, multidimensional task. Many prioritization tools and online interpretation resources exist, and professional organizations have offered clinical guidelines for review and return of prioritization results. In this Review, we describe the strengths and weaknesses of widely used computational approaches, explain their roles in the diagnostic and discovery process and discuss how they can inform (and misinform) expert reviewers. We place variant prioritization in the wider context of gene prioritization, burden testing and genotype-phenotype association, and we discuss opportunities and challenges introduced by whole-genome sequencing.
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Affiliation(s)
- Karen Eilbeck
- Department of Biomedical Informatics, School of Medicine, University of Utah, 421 Wakara Way, Suite 120, Salt Lake City, Utah 84108, USA
| | - Aaron Quinlan
- Department of Biomedical Informatics, School of Medicine, University of Utah, 421 Wakara Way, Suite 120, Salt Lake City, Utah 84108, USA
- Department of Human Genetics, Eccles Institute of Human Genetics, School of Medicine, University of Utah, 15 S 2030 E, Salt Lake City, Utah 84112, USA
| | - Mark Yandell
- Department of Human Genetics, Eccles Institute of Human Genetics, School of Medicine, University of Utah, 15 S 2030 E, Salt Lake City, Utah 84112, USA
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14
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Kharrat M, Kamoun Y, Kamoun F, Ellouze E, Maalej M, Fendri-Kriaa N, Ammar-Keskes L, Belghith N, Gargouri A, Triki C, Fakhfakh F. Clinical, Molecular, and Computational Analysis in Patients With a Novel Double Mutation and a New Synonymous Variant in MeCP2: Report of the First Missense Mutation Within the AT-hook1 Cluster in Rett Syndrome. J Child Neurol 2017; 32:694-703. [PMID: 28399682 DOI: 10.1177/0883073817701622] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Rett syndrome is an X-linked neurodevelopmental disorder, primarily caused by MECP2 mutations. In this study, clinical, molecular and bioinformatics analyses were performed in Rett patients to understand the relationship between MECP2 mutation type and the clinical severity. Two double MeCP2 mutations were detected: a novel one (p.G185 V in cis with p.R255X) in P1 and a known one (p.P179 S in cis with p.R255X) in P2. Besides, a novel synonymous mutation (c.807C>T; p.G269G), which could affect mRNA splicing, was identified in P3. The results from clinical severity analysis have shown that P1 was more severely affected than P2 with CSS being 35 and 14, respectively. Therefore, the phenotypic variability in P1 and P2 could be explained by the potential pathogenic effect of the RTT-causing missense mutation p.G185 V in the AT-hook1. In conclusion, clinical, molecular, and in silico investigations in the studied patients have been proven to be substantial for the genotype-phenotype correlation.
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Affiliation(s)
- Marwa Kharrat
- 1 Laboratory of Molecular and Functional Genetics, Faculty of Science of Sfax, University of Sfax, Sfax, Tunisia.,2 Laboratory of Human Molecular Genetics, Faculty of Medicine, Sfax, Tunisia
| | - Yosra Kamoun
- 3 Laboratory of Molecular Biotechnologie of Eukaryotes, Centre of Biotechnology of Sfax, University of Sfax, Sfax, Tunisia
| | - Fatma Kamoun
- 4 Service de Neurologie Infantile, C.H.U. Hédi Chaker de Sfax, Tunisia
| | - Emna Ellouze
- 4 Service de Neurologie Infantile, C.H.U. Hédi Chaker de Sfax, Tunisia
| | - Marwa Maalej
- 2 Laboratory of Human Molecular Genetics, Faculty of Medicine, Sfax, Tunisia
| | - Nourhene Fendri-Kriaa
- 1 Laboratory of Molecular and Functional Genetics, Faculty of Science of Sfax, University of Sfax, Sfax, Tunisia
| | - Leila Ammar-Keskes
- 2 Laboratory of Human Molecular Genetics, Faculty of Medicine, Sfax, Tunisia
| | - Neila Belghith
- 2 Laboratory of Human Molecular Genetics, Faculty of Medicine, Sfax, Tunisia
| | - Ali Gargouri
- 3 Laboratory of Molecular Biotechnologie of Eukaryotes, Centre of Biotechnology of Sfax, University of Sfax, Sfax, Tunisia
| | - Chahnez Triki
- 4 Service de Neurologie Infantile, C.H.U. Hédi Chaker de Sfax, Tunisia
| | - Faiza Fakhfakh
- 1 Laboratory of Molecular and Functional Genetics, Faculty of Science of Sfax, University of Sfax, Sfax, Tunisia
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15
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From Function to Phenotype: Impaired DNA Binding and Clustering Correlates with Clinical Severity in Males with Missense Mutations in MECP2. Sci Rep 2016; 6:38590. [PMID: 27929079 PMCID: PMC5144150 DOI: 10.1038/srep38590] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 11/11/2016] [Indexed: 11/25/2022] Open
Abstract
Mutations in the MECP2 gene cause Rett syndrome (RTT). MeCP2 binds to chromocentric DNA through its methyl CpG-binding domain (MBD) to regulate gene expression. In heterozygous females the variable phenotypic severity is modulated by non-random X-inactivation, thus making genotype-phenotype comparisons unreliable. However, genotype-phenotype correlations in males with hemizygousMECP2 mutations can provide more accurate insights in to the true biological effect of specific mutations. Here, we compared chromatin organization and binding dynamics for twelve MeCP2 missense mutations (including two novel and the five most common MBD missense RTT mutations) and identifiedacorrelation with phenotype in hemizygous males. We observed impaired interaction of MeCP2-DNA for mutations around the MBD-DNA binding interface, and defective chromatin clustering for distal MBD mutations. Furthermore, binding and mobility dynamics show a gradient of impairment depending on the amino acid properties and tertiary structure within the MBD. Interestingly, a wide range of phenotypic/clinical severity, ranging from neonatal encephalopathy to mild psychiatric abnormalities were observed and all are consistent with our functional/molecular results. Overall, clinical severity showed a direct correlation with the functional impairment of MeCP2. These mechanistic and phenotypic correlations of MeCP2 mutations will enable improved and individualized diagnostics, and may lead to personalized therapeutic interventions.
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16
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Gotea V, Gartner JJ, Qutob N, Elnitski L, Samuels Y. The functional relevance of somatic synonymous mutations in melanoma and other cancers. Pigment Cell Melanoma Res 2016; 28:673-84. [PMID: 26300548 DOI: 10.1111/pcmr.12413] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2015] [Accepted: 08/19/2015] [Indexed: 01/07/2023]
Abstract
Recent technological advances in sequencing have flooded the field of cancer research with knowledge about somatic mutations for many different cancer types. Most cancer genomics studies focus on mutations that alter the amino acid sequence, ignoring the potential impact of synonymous mutations. However, accumulating experimental evidence has demonstrated clear consequences for gene function, leading to a widespread recognition of the functional role of synonymous mutations and their causal connection to various diseases. Here, we review the evidence supporting the direct impact of synonymous mutations on gene function via gene splicing; mRNA stability, folding, and translation; protein folding; and miRNA-based regulation of expression. These results highlight the functional contribution of synonymous mutations to oncogenesis and the need to further investigate their detection and prioritization for experimental assessment.
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Affiliation(s)
- Valer Gotea
- Translational and Functional Genomics Branch, National Human Genome Research Institute, NIH, Bethesda, MD, USA
| | - Jared J Gartner
- Surgery Branch, National Cancer Institute, NIH, Bethesda, MD, USA
| | - Nouar Qutob
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Laura Elnitski
- Translational and Functional Genomics Branch, National Human Genome Research Institute, NIH, Bethesda, MD, USA
| | - Yardena Samuels
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
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17
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KhorshidAhmad T, Acosta C, Cortes C, Lakowski TM, Gangadaran S, Namaka M. Transcriptional Regulation of Brain-Derived Neurotrophic Factor (BDNF) by Methyl CpG Binding Protein 2 (MeCP2): a Novel Mechanism for Re-Myelination and/or Myelin Repair Involved in the Treatment of Multiple Sclerosis (MS). Mol Neurobiol 2015; 53:1092-1107. [PMID: 25579386 DOI: 10.1007/s12035-014-9074-1] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Accepted: 12/29/2014] [Indexed: 12/13/2022]
Abstract
Multiple sclerosis (MS) is a chronic progressive, neurological disease characterized by the targeted immune system-mediated destruction of central nervous system (CNS) myelin. Autoreactive CD4+ T helper cells have a key role in orchestrating MS-induced myelin damage. Once activated, circulating Th1-cells secrete a variety of inflammatory cytokines that foster the breakdown of blood-brain barrier (BBB) eventually infiltrating into the CNS. Inside the CNS, they become reactivated upon exposure to the myelin structural proteins and continue to produce inflammatory cytokines such as tumor necrosis factor α (TNFα) that leads to direct activation of antibodies and macrophages that are involved in the phagocytosis of myelin. Proliferating oligodendrocyte precursors (OPs) migrating to the lesion sites are capable of acute remyelination but unable to completely repair or restore the immune system-mediated myelin damage. This results in various permanent clinical neurological disabilities such as cognitive dysfunction, fatigue, bowel/bladder abnormalities, and neuropathic pain. At present, there is no cure for MS. Recent remyelination and/or myelin repair strategies have focused on the role of the neurotrophin brain-derived neurotrophic factor (BDNF) and its upstream transcriptional repressor methyl CpG binding protein (MeCP2). Research in the field of epigenetic therapeutics involving histone deacetylase (HDAC) inhibitors and lysine acetyl transferase (KAT) inhibitors is being explored to repress the detrimental effects of MeCP2. This review will address the role of MeCP2 and BDNF in remyelination and/or myelin repair and the potential of HDAC and KAT inhibitors as novel therapeutic interventions for MS.
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Affiliation(s)
- Tina KhorshidAhmad
- College of Pharmacy, University of Manitoba, 750 McDermot Avenue, Winnipeg, R3E 0T5, Manitoba, Canada.,Manitoba Multiple Sclerosis Research Network Organization (MMSRNO), Winnipeg, Canada
| | - Crystal Acosta
- College of Pharmacy, University of Manitoba, 750 McDermot Avenue, Winnipeg, R3E 0T5, Manitoba, Canada.,Manitoba Multiple Sclerosis Research Network Organization (MMSRNO), Winnipeg, Canada
| | - Claudia Cortes
- College of Pharmacy, University of Manitoba, 750 McDermot Avenue, Winnipeg, R3E 0T5, Manitoba, Canada.,Manitoba Multiple Sclerosis Research Network Organization (MMSRNO), Winnipeg, Canada
| | - Ted M Lakowski
- College of Pharmacy, University of Manitoba, 750 McDermot Avenue, Winnipeg, R3E 0T5, Manitoba, Canada.,Manitoba Multiple Sclerosis Research Network Organization (MMSRNO), Winnipeg, Canada
| | - Surendiran Gangadaran
- College of Pharmacy, University of Manitoba, 750 McDermot Avenue, Winnipeg, R3E 0T5, Manitoba, Canada.,Manitoba Multiple Sclerosis Research Network Organization (MMSRNO), Winnipeg, Canada
| | - Michael Namaka
- College of Pharmacy, University of Manitoba, 750 McDermot Avenue, Winnipeg, R3E 0T5, Manitoba, Canada. .,Manitoba Multiple Sclerosis Research Network Organization (MMSRNO), Winnipeg, Canada. .,College of Medicine, University of Manitoba, Winnipeg, Canada. .,School of Medical Rehabilitation, College of Medicine, University of Manitoba, Winnipeg, Canada.
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18
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Hunt RC, Simhadri VL, Iandoli M, Sauna ZE, Kimchi-Sarfaty C. Exposing synonymous mutations. Trends Genet 2014; 30:308-21. [PMID: 24954581 DOI: 10.1016/j.tig.2014.04.006] [Citation(s) in RCA: 230] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 04/16/2014] [Accepted: 04/17/2014] [Indexed: 12/12/2022]
Abstract
Synonymous codon changes, which do not alter protein sequence, were previously thought to have no functional consequence. Although this concept has been overturned in recent years, there is no unique mechanism by which these changes exert biological effects. A large repertoire of both experimental and bioinformatic methods has been developed to understand the effects of synonymous variants. Results from this body of work have provided global insights into how biological systems exploit the degeneracy of the genetic code to control gene expression, protein folding efficiency, and the coordinated expression of functionally related gene families. Although it is now clear that synonymous variants are important in a variety of contexts, from human disease to the safety and efficacy of therapeutic proteins, there is no clear consensus on the approaches to identify and validate these changes. Here, we review the diverse methods to understand the effects of synonymous mutations.
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Affiliation(s)
- Ryan C Hunt
- Division of Hematology, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD, USA.
| | - Vijaya L Simhadri
- Division of Hematology, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD, USA
| | - Matthew Iandoli
- Division of Hematology, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD, USA
| | - Zuben E Sauna
- Division of Hematology, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD, USA.
| | - Chava Kimchi-Sarfaty
- Division of Hematology, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD, USA.
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19
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Abstract
Rett syndrome (RTT) is a severe and progressive neurological disorder, which mainly affects young females. Mutations of the methyl-CpG binding protein 2 (MECP2) gene are the most prevalent cause of classical RTT cases. MECP2 mutations or altered expression are also associated with a spectrum of neurodevelopmental disorders such as autism spectrum disorders with recent links to fetal alcohol spectrum disorders. Collectively, MeCP2 relation to these neurodevelopmental disorders highlights the importance of understanding the molecular mechanisms by which MeCP2 impacts brain development, mental conditions, and compromised brain function. Since MECP2 mutations were discovered to be the primary cause of RTT, a significant progress has been made in the MeCP2 research, with respect to the expression, function and regulation of MeCP2 in the brain and its contribution in RTT pathogenesis. To date, there have been intensive efforts in designing effective therapeutic strategies for RTT benefiting from mouse models and cells collected from RTT patients. Despite significant progress in MeCP2 research over the last few decades, there is still a knowledge gap between the in vitro and in vivo research findings and translating these findings into effective therapeutic interventions in human RTT patients. In this review, we will provide a synopsis of Rett syndrome as a severe neurological disorder and will discuss the role of MeCP2 in RTT pathophysiology.
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20
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Olson CO, Zachariah RM, Ezeonwuka CD, Liyanage VRB, Rastegar M. Brain region-specific expression of MeCP2 isoforms correlates with DNA methylation within Mecp2 regulatory elements. PLoS One 2014; 9:e90645. [PMID: 24594659 PMCID: PMC3940938 DOI: 10.1371/journal.pone.0090645] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Accepted: 02/05/2014] [Indexed: 01/08/2023] Open
Abstract
MeCP2 is a critical epigenetic regulator in brain and its abnormal expression or compromised function leads to a spectrum of neurological disorders including Rett Syndrome and autism. Altered expression of the two MeCP2 isoforms, MeCP2E1 and MeCP2E2 has been implicated in neurological complications. However, expression, regulation and functions of the two isoforms are largely uncharacterized. Previously, we showed the role of MeCP2E1 in neuronal maturation and reported MeCP2E1 as the major protein isoform in the adult mouse brain, embryonic neurons and astrocytes. Recently, we showed that DNA methylation at the regulatory elements (REs) within the Mecp2 promoter and intron 1 impact the expression of Mecp2 isoforms in differentiating neural stem cells. This current study is aimed for a comparative analysis of temporal, regional and cell type-specific expression of MeCP2 isoforms in the developing and adult mouse brain. MeCP2E2 displayed a later expression onset than MeCP2E1 during mouse brain development. In the adult female and male brain hippocampus, both MeCP2 isoforms were detected in neurons, astrocytes and oligodendrocytes. Furthermore, MeCP2E1 expression was relatively uniform in different brain regions (olfactory bulb, striatum, cortex, hippocampus, thalamus, brainstem and cerebellum), whereas MeCP2E2 showed differential enrichment in these brain regions. Both MeCP2 isoforms showed relatively similar distribution in these brain regions, except for cerebellum. Lastly, a preferential correlation was observed between DNA methylation at specific CpG dinucleotides within the REs and Mecp2 isoform-specific expression in these brain regions. Taken together, we show that MeCP2 isoforms display differential expression patterns during brain development and in adult mouse brain regions. DNA methylation patterns at the Mecp2 REs may impact this differential expression of Mecp2/MeCP2 isoforms in brain regions. Our results significantly contribute towards characterizing the expression profiles of Mecp2/MeCP2 isoforms and thereby provide insights on the potential role of MeCP2 isoforms in the developing and adult brain.
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Affiliation(s)
- Carl O. Olson
- Regenerative Medicine Program, and Department of Biochemistry and Medical Genetics, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Robby M. Zachariah
- Regenerative Medicine Program, and Department of Biochemistry and Medical Genetics, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Chinelo D. Ezeonwuka
- Regenerative Medicine Program, and Department of Biochemistry and Medical Genetics, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Vichithra R. B. Liyanage
- Regenerative Medicine Program, and Department of Biochemistry and Medical Genetics, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Mojgan Rastegar
- Regenerative Medicine Program, and Department of Biochemistry and Medical Genetics, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
- * E-mail:
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