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Pavešković M, De-Paula RB, Ojelade SA, Tantry EK, Kochukov MY, Bao S, Veeraragavan S, Garza AR, Srivastava S, Song SY, Fujita M, Duong DM, Bennett DA, De Jager PL, Seyfried NT, Dickinson ME, Heaney JD, Arenkiel BR, Shulman JM. Alzheimer's disease risk gene CD2AP is a dose-sensitive determinant of synaptic structure and plasticity. Hum Mol Genet 2024:ddae115. [PMID: 39146503 DOI: 10.1093/hmg/ddae115] [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: 02/27/2024] [Revised: 06/15/2024] [Indexed: 08/17/2024] Open
Abstract
CD2-Associated protein (CD2AP) is a candidate susceptibility gene for Alzheimer's disease, but its role in the mammalian central nervous system remains largely unknown. We show that CD2AP protein is broadly expressed in the adult mouse brain, including within cortical and hippocampal neurons, where it is detected at pre-synaptic terminals. Deletion of Cd2ap altered dendritic branching and spine density, and impaired ubiquitin-proteasome system activity. Moreover, in mice harboring either one or two copies of a germline Cd2ap null allele, we noted increased paired-pulse facilitation at hippocampal Schaffer-collateral synapses, consistent with a haploinsufficient requirement for pre-synaptic release. Whereas conditional Cd2ap knockout in the brain revealed no gross behavioral deficits in either 3.5- or 12-month-old mice, Cd2ap heterozygous mice demonstrated subtle impairments in discrimination learning using a touchscreen task. Based on unbiased proteomics, partial or complete loss of Cd2ap triggered perturbation of proteins with roles in protein folding, lipid metabolism, proteostasis, and synaptic function. Overall, our results reveal conserved, dose-sensitive requirements for CD2AP in the maintenance of neuronal structure and function, including synaptic homeostasis and plasticity, and inform our understanding of possible cell-type specific mechanisms in Alzheimer's Disease.
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Affiliation(s)
- Matea Pavešković
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, 1250 Moursund Street, Houston, TX 77030, United States
- Department of Neurology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States
| | - Ruth B De-Paula
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, 1250 Moursund Street, Houston, TX 77030, United States
- Department of Neurology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States
- Quantitative and Computational Biology Program, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States
| | - Shamsideen A Ojelade
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, 1250 Moursund Street, Houston, TX 77030, United States
- Department of Neurology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States
| | - Evelyne K Tantry
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, 1250 Moursund Street, Houston, TX 77030, United States
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States
| | - Mikhail Y Kochukov
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, 1250 Moursund Street, Houston, TX 77030, United States
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States
| | - Suyang Bao
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, 1250 Moursund Street, Houston, TX 77030, United States
- Development, Disease Models, and Therapeutics Graduate Program, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States
| | - Surabi Veeraragavan
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, 1250 Moursund Street, Houston, TX 77030, United States
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States
| | - Alexandra R Garza
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, 1250 Moursund Street, Houston, TX 77030, United States
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States
| | - Snigdha Srivastava
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, 1250 Moursund Street, Houston, TX 77030, United States
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States
- Medical Scientist Training Program, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States
| | - Si-Yuan Song
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, 1250 Moursund Street, Houston, TX 77030, United States
| | - Masashi Fujita
- Center for Translational and Computational Neuroimmunology, Department of Neurology and the Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Irving Medical Center, 630 West 168th Street, New York, NY, United States
| | - Duc M Duong
- Departments of Biochemistry and Neurology, Emory University School of Medicine, 100 Woodruff Circle, Atlanta, GA 30322, United States
| | - David A Bennett
- Rush Alzheimer's Disease Center, Rush University Medical Center, 600 S. Paulina Street, Chicago, IL 60612, United States
| | - Philip L De Jager
- Center for Translational and Computational Neuroimmunology, Department of Neurology and the Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Irving Medical Center, 630 West 168th Street, New York, NY, United States
| | - Nicholas T Seyfried
- Departments of Biochemistry and Neurology, Emory University School of Medicine, 100 Woodruff Circle, Atlanta, GA 30322, United States
| | - Mary E Dickinson
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States
| | - Jason D Heaney
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States
| | - Benjamin R Arenkiel
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, 1250 Moursund Street, Houston, TX 77030, United States
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States
| | - Joshua M Shulman
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, 1250 Moursund Street, Houston, TX 77030, United States
- Department of Neurology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States
- Center for Alzheimer's and Neurodegenerative Diseases, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States
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Wang J, Gao G, Wang D. Developing AAV-delivered nonsense suppressor tRNAs for neurological disorders. Neurotherapeutics 2024; 21:e00391. [PMID: 38959711 PMCID: PMC11269797 DOI: 10.1016/j.neurot.2024.e00391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Revised: 05/29/2024] [Accepted: 06/19/2024] [Indexed: 07/05/2024] Open
Abstract
Adeno-associated virus (AAV)-based gene therapy is a clinical stage therapeutic modality for neurological disorders. A common genetic defect in myriad monogenic neurological disorders is nonsense mutations that account for about 11% of all human pathogenic mutations. Stop codon readthrough by suppressor transfer RNA (sup-tRNA) has long been sought as a potential gene therapy approach to target nonsense mutations, but hindered by inefficient in vivo delivery. The rapid advances in AAV delivery technology have not only powered gene therapy development but also enabled in vivo preclinical assessment of a range of nucleic acid therapeutics, such as sup-tRNA. Compared with conventional AAV gene therapy that delivers a transgene to produce therapeutic proteins, AAV-delivered sup-tRNA has several advantages, such as small gene sizes and operating within the endogenous gene expression regulation, which are important considerations for treating some neurological disorders. This review will first examine sup-tRNA designs and delivery by AAV vectors. We will then analyze how AAV-delivered sup-tRNA can potentially address some neurological disorders that are challenging to conventional gene therapy, followed by discussing available mouse models of neurological diseases for in vivo preclinical testing. Potential challenges for AAV-delivered sup-tRNA to achieve therapeutic efficacy and safety will also be discussed.
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Affiliation(s)
- Jiaming Wang
- Horae Gene Therapy Center, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA; Department of Microbiology and Physiological Systems, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - Guangping Gao
- Horae Gene Therapy Center, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA; Department of Microbiology and Physiological Systems, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA.
| | - Dan Wang
- Horae Gene Therapy Center, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA; RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA.
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Dennys CN, Vermudez SAD, Deacon RJM, Sierra-Delgado JA, Rich K, Zhang X, Buch A, Weiss K, Moxley Y, Rajpal H, Espinoza FD, Powers S, Ávila AS, Gogliotti RG, Cogram P, Niswender CM, Meyer KC. MeCP2 gene therapy ameliorates disease phenotype in mouse model for Pitt Hopkins syndrome. Neurotherapeutics 2024:e00376. [PMID: 38876822 DOI: 10.1016/j.neurot.2024.e00376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 05/07/2024] [Accepted: 05/14/2024] [Indexed: 06/16/2024] Open
Abstract
The neurodevelopmental disorder Pitt Hopkins syndrome (PTHS) causes clinical symptoms similar to Rett syndrome (RTT) patients. However, RTT is caused by MECP2 mutations whereas mutations in the TCF4 gene lead to PTHS. The mechanistic commonalities underling these two disorders are unknown, but their shared symptomology suggest that convergent pathway-level disruption likely exists. We reprogrammed patient skin derived fibroblasts into induced neuronal progenitor cells. Interestingly, we discovered that MeCP2 levels were decreased in PTHS patient iNPCs relative to healthy controls and that both iNPCs and iAstrocytes displayed defects in function and differentiation in a mutation-specific manner. When Tcf4+/- mice were genetically crossed with mice overexpressing MeCP2, molecular and phenotypic defects were significantly ameliorated, underlining and important role of MeCP2 in PTHS pathology. Importantly, post-natal intracerebroventricular gene replacement therapy with adeno-associated viral vector serotype 9 (AAV9)-expressing MeCP2 (AAV9.P546.MeCP2) significantly improved iNPC and iAstrocyte function and effectively ameliorated histological and behavioral defects in Tcf4+/- mice. Combined, our data suggest a previously unknown role of MeCP2 in PTHS pathology and common pathways that might be affected in multiple neurodevelopmental disorders. Our work highlights potential novel therapeutic targets for PTHS, including upregulation of MeCP2 expression or its downstream targets or, potentially, MeCP2-based gene therapy.
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Affiliation(s)
- Cassandra N Dennys
- Center for Gene Therapy, The Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, OH, USA
| | - Sheryl Anne D Vermudez
- Department of Pharmacology and Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, USA
| | - Robert J M Deacon
- Department of Genetics, Institute of Ecology and Biodiversity, Faculty of Science, University of Chile, Chile
| | - J Andrea Sierra-Delgado
- Center for Gene Therapy, The Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, OH, USA
| | - Kelly Rich
- Center for Gene Therapy, The Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, OH, USA
| | - Xiaojin Zhang
- Center for Gene Therapy, The Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, OH, USA
| | - Aditi Buch
- Department of Pharmacology and Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, USA
| | - Kelly Weiss
- Department of Pharmacology and Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, USA
| | - Yuta Moxley
- Department of Pharmacology and Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, USA
| | - Hemangi Rajpal
- Department of Pharmacology and Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, USA
| | - Francisca D Espinoza
- Faculty of Medicine, Universidad Católica de la Santísima Concepción, Concepción, 4090541, Chile
| | - Samantha Powers
- Center for Gene Therapy, The Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, OH, USA
| | - Ariel S Ávila
- Faculty of Medicine, Universidad Católica de la Santísima Concepción, Concepción, 4090541, Chile
| | - Rocco G Gogliotti
- Department of Molecular Pharmacology and Neuroscience, Loyola University Chicago, Maywood, IL 60153, USA
| | - Patricia Cogram
- Department of Genetics, Institute of Ecology and Biodiversity, Faculty of Science, University of Chile, Chile
| | - Colleen M Niswender
- Department of Pharmacology and Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, USA; Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN 37232, USA; Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37232, USA; Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Kathrin C Meyer
- Center for Gene Therapy, The Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, OH, USA; Department of Pediatrics, The Ohio State University Medical Center, Columbus, OH, USA; Department of Neuroscience, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
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4
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Martinez D, Jiang E, Zhou Z. Overcoming genetic and cellular complexity to study the pathophysiology of X-linked intellectual disabilities. J Neurodev Disord 2024; 16:5. [PMID: 38424476 PMCID: PMC10902969 DOI: 10.1186/s11689-024-09517-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2023] [Accepted: 02/04/2024] [Indexed: 03/02/2024] Open
Abstract
X-linked genetic causes of intellectual disability (ID) account for a substantial proportion of cases and remain poorly understood, in part due to the heterogeneous expression of X-linked genes in females. This is because most genes on the X chromosome are subject to random X chromosome inactivation (XCI) during early embryonic development, which results in a mosaic pattern of gene expression for a given X-linked mutant allele. This mosaic expression produces substantial complexity, especially when attempting to study the already complicated neural circuits that underly behavior, thus impeding the understanding of disease-related pathophysiology and the development of therapeutics. Here, we review a few selected X-linked forms of ID that predominantly affect heterozygous females and the current obstacles for developing effective therapies for such disorders. We also propose a genetic strategy to overcome the complexity presented by mosaicism in heterozygous females and highlight specific tools for studying synaptic and circuit mechanisms, many of which could be shared across multiple forms of intellectual disability.
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Affiliation(s)
- Dayne Martinez
- Department of Genetics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, 19102, USA
- Medical Scientist Training Program, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, 19102, USA
| | - Evan Jiang
- Department of Genetics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, 19102, USA
- Medical Scientist Training Program, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, 19102, USA
| | - Zhaolan Zhou
- Department of Genetics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, 19102, USA.
- Medical Scientist Training Program, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, 19102, USA.
- Department of Neuroscience, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, 19102, USA.
- Intellectual and Developmental Disabilities Research Center, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA.
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5
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Neul JL, Benke TA, Marsh ED, Suter B, Silveira L, Fu C, Peters SU, Percy AK. Top caregiver concerns in Rett syndrome and related disorders: data from the US natural history study. J Neurodev Disord 2023; 15:33. [PMID: 37833681 PMCID: PMC10571464 DOI: 10.1186/s11689-023-09502-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Accepted: 09/20/2023] [Indexed: 10/15/2023] Open
Abstract
OBJECTIVE Recent advances in the understanding of neurodevelopmental disorders such as Rett syndrome (RTT) have enabled the discovery of novel therapeutic approaches that require formal clinical evaluation of efficacy. Clinical trial success depends on outcome measures that assess clinical features that are most impactful for affected individuals. To determine the top concerns in RTT and RTT-related disorders we asked caregivers to list the top caregiver concerns to guide the development and selection of appropriate clinical trial outcome measures for these disorders. METHODS Caregivers of participants enrolled in the US Natural History Study of RTT and RTT-related disorders (n = 925) were asked to identify the top 3 concerning problems impacting the affected participant. We generated a weighted list of top caregiver concerns for each of the diagnostic categories and compared results between the disorders. Further, for classic RTT, caregiver concerns were analyzed by age, clinical severity, and common RTT-causing mutations in MECP2. RESULTS The top caregiver concerns for classic RTT were effective communication, seizures, walking/balance issues, lack of hand use, and constipation. The frequency of the top caregiver concerns for classic RTT varied by age, clinical severity, and specific mutations, consistent with known variation in the frequency of clinical features across these domains. Caregivers of participants with increased seizure severity often ranked seizures as the first concern, whereas caregivers of participants without active seizures often ranked hand use or communication as the top concern. Comparison across disorders found commonalities in the top caregiver concerns between classic RTT, atypical RTT, MECP2 duplication syndrome, CDKL5 deficiency disorder, and FOXG1 syndrome; however, distinct differences in caregiver concerns between these disorders are consistent with the relative prevalence and impact of specific clinical features. CONCLUSION The top caregiver concerns for individuals with RTT and RTT-related disorders reflect the impact of the primary clinical symptoms of these disorders. This work is critical in the development of meaningful therapies, as optimal therapy should address these concerns. Further, outcome measures to be utilized in clinical trials should assess these clinical issues identified as most concerning by caregivers.
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Affiliation(s)
- Jeffrey L Neul
- Department of Pediatrics, Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - Timothy A Benke
- University of Colorado School of Medicine/Children's Hospital Colorado, Aurora, CO, USA
| | - Eric D Marsh
- Children's Hospital of Philadelphia, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | | | - Lori Silveira
- University of Colorado School of Medicine/Children's Hospital Colorado, Aurora, CO, USA
| | - Cary Fu
- Department of Pediatrics, Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Sarika U Peters
- Department of Pediatrics, Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Alan K Percy
- University of Alabama at Birmingham, Birmingham, AL, USA
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Wong KM, Wegener E, Baradaran-Heravi A, Huppke B, Gärtner J, Huppke P. Evaluation of Novel Enhancer Compounds in Gentamicin-Mediated Readthrough of Nonsense Mutations in Rett Syndrome. Int J Mol Sci 2023; 24:11665. [PMID: 37511424 PMCID: PMC10380790 DOI: 10.3390/ijms241411665] [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: 06/21/2023] [Revised: 07/13/2023] [Accepted: 07/14/2023] [Indexed: 07/30/2023] Open
Abstract
Rett syndrome (RTT), a severe X-linked neurodevelopmental disorder, is primarily caused by mutations in the methyl CpG binding protein 2 gene (MECP2). Over 35% RTT patients carry nonsense mutation in MECP2, making it a suitable candidate disease for nonsense suppression therapy. In our previous study, gentamicin was found to induce readthrough of MECP2 nonsense mutations with modest efficiency. Given the recent discovery of readthrough enhancers, CDX compounds, we herein evaluated the potentiation effect of CDX5-1, CDX5-288, and CDX6-180 on gentamicin-mediated readthrough efficiency in transfected HeLa cell lines bearing the four most common MECP2 nonsense mutations. We showed that all three CDX compounds potentiated gentamicin-mediated readthrough and increased full-length MeCP2 protein levels in cells expressing the R168X, R255X, R270X, and R294X nonsense mutations. Among all three CDX compounds, CDX5-288 was the most potent enhancer and enabled the use of reduced doses of gentamicin, thus mitigating the toxicity. Furthermore, we successfully demonstrated the upregulation of full-length Mecp2 protein expression in fibroblasts derived from Mecp2R255X/Y mice through combinatorial treatment. Taken together, findings demonstrate the feasibility of this combinatorial approach to nonsense suppression therapy for a subset of RTT patients.
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Affiliation(s)
- Keit Men Wong
- Department of Neuropediatrics, Jena University Hospital, 07747 Jena, Germany
- Center for Rare Diseases, Jena University Hospital, 07747 Jena, Germany
| | - Eike Wegener
- Department of Pediatrics and Adolescent Medicine, Division of Neuropediatrics, Pediatric Neurology University Medical Center Göttingen, Georg August University Göttingen, 37075 Göttingen, Germany
| | - Alireza Baradaran-Heravi
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver BC V6T 1Z3, Canada
| | - Brenda Huppke
- Department of Neuropediatrics, Jena University Hospital, 07747 Jena, Germany
- Center for Rare Diseases, Jena University Hospital, 07747 Jena, Germany
| | - Jutta Gärtner
- Department of Pediatrics and Adolescent Medicine, Division of Neuropediatrics, Pediatric Neurology University Medical Center Göttingen, Georg August University Göttingen, 37075 Göttingen, Germany
| | - Peter Huppke
- Department of Neuropediatrics, Jena University Hospital, 07747 Jena, Germany
- Center for Rare Diseases, Jena University Hospital, 07747 Jena, Germany
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Oluigbo DC. Rett Syndrome: A Tale of Altered Genetics, Synaptic Plasticity, and Neurodevelopmental Dynamics. Cureus 2023; 15:e41555. [PMID: 37554594 PMCID: PMC10405636 DOI: 10.7759/cureus.41555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/07/2023] [Indexed: 08/10/2023] Open
Abstract
Rett syndrome (RTT) is a neurodevelopmental disorder that is a leading cause of severe cognitive and physical impairment. RTT typically occurs in females, although rare cases of males with the disease exist. Its genetic cause, symptoms, and clinical progression timeline have also become well-documented since its initial discovery. However, a relatively late diagnosis and lack of an available cure signify that our understanding of the disease is incomplete. Innovative research methods and tools are thereby helping to fill gaps in our knowledge of RTT. Specifically, mouse models of RTT, video analysis, and retrospective parental analysis are well-established tools that provide valuable insights into RTT. Moreover, current and anticipated treatment options are improving the quality of life of the RTT patient population. Collectively, these developments are creating optimistic future perspectives for RTT.
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Affiliation(s)
- David C Oluigbo
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, USA
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Palmieri M, Pozzer D, Landsberger N. Advanced genetic therapies for the treatment of Rett syndrome: state of the art and future perspectives. Front Neurosci 2023; 17:1172805. [PMID: 37304036 PMCID: PMC10248472 DOI: 10.3389/fnins.2023.1172805] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Accepted: 05/02/2023] [Indexed: 06/13/2023] Open
Abstract
Loss and gain of functions mutations in the X-linked MECP2 (methyl-CpG-binding protein 2) gene are responsible for a set of generally severe neurological disorders that can affect both genders. In particular, Mecp2 deficiency is mainly associated with Rett syndrome (RTT) in girls, while duplication of the MECP2 gene leads, mainly in boys, to the MECP2 duplication syndrome (MDS). No cure is currently available for MECP2 related disorders. However, several studies have reported that by re-expressing the wild-type gene is possible to restore defective phenotypes of Mecp2 null animals. This proof of principle endorsed many laboratories to search for novel therapeutic strategies to cure RTT. Besides pharmacological approaches aimed at modulating MeCP2-downstream pathways, genetic targeting of MECP2 or its transcript have been largely proposed. Remarkably, two studies focused on augmentative gene therapy were recently approved for clinical trials. Both use molecular strategies to well-control gene dosage. Notably, the recent development of genome editing technologies has opened an alternative way to specifically target MECP2 without altering its physiological levels. Other attractive approaches exclusively applicable for nonsense mutations are the translational read-through (TR) and t-RNA suppressor therapy. Reactivation of the MECP2 locus on the silent X chromosome represents another valid choice for the disease. In this article, we intend to review the most recent genetic interventions for the treatment of RTT, describing the current state of the art, and the related advantages and concerns. We will also discuss the possible application of other advanced therapies, based on molecular delivery through nanoparticles, already proposed for other neurological disorders but still not tested in RTT.
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Affiliation(s)
- Michela Palmieri
- Rett Research Unit, Division of Neuroscience, San Raffaele Hospital (IRCCS), Milan, Italy
| | - Diego Pozzer
- Rett Research Unit, Division of Neuroscience, San Raffaele Hospital (IRCCS), Milan, Italy
| | - Nicoletta Landsberger
- Rett Research Unit, Division of Neuroscience, San Raffaele Hospital (IRCCS), Milan, Italy
- Department of Medical Biotechnology and Translational Medicine, Faculty of Medicine and Surgery, University of Milan, Milan, Italy
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9
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Neul JL, Benke TA, Marsh ED, Suter B, Silveira L, Fu C, Peters SU, Percy AK. Top Caregiver Concerns in Rett syndrome and related disorders: data from the US Natural History Study. RESEARCH SQUARE 2023:rs.3.rs-2566253. [PMID: 36993737 PMCID: PMC10055548 DOI: 10.21203/rs.3.rs-2566253/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: 03/31/2023]
Abstract
Objective Recent advances in the understanding of neurodevelopmental disorders such as Rett syndrome (RTT) has enabled development of novel therapeutic approaches that are currently undergoing clinical evaluation or are proposed to move into clinical development. Clinical trial success depends on outcome measures that assess clinical features that are most impactful for affected individuals. To determine the top concerns in RTT and RTT-related disorders we asked caregivers to list the top clinical concerns in order to gain information to guide the development and selection of outcome measures for future clinical trials. Methods Caregivers of participants enrolled in the US Natural History Study of RTT and related disorders were asked to identify the top 3 concerning problems impacting the affected participant. We generated a weighted list of top caregiver concerns for each of the diagnostic categories and compared results between the disorders. Further, for Classic RTT, caregiver concerns were analyzed by age, clinical severity, and common RTT-causing mutations in MECP2. Results The top caregiver concerns for Classic RTT were effective communication, seizures, walking/balance issues, lack of hand use, and constipation. The rank order of the frequency of the top caregiver concerns for Classic RTT varied by age, clinical severity, and specific mutations, consistent with known variation in the frequency of clinical features across these domains. The frequency of caregiver concern for seizures, hand use, and spoken language increased in relation to clinician assessed severity in these clinical domains, showing consistency between clinician assessments and caregiver concerns. Comparison across disorders found commonalities in the top caregiver concerns between Classic RTT, Atypical RTT, MECP2 Duplication Syndrome, CDKL5 Deficiency Disorder, and FOXG1 Syndrome; however, distinct differences in caregiver concerns between these disorders are consistent with the relative prevalence and impact of specific clinical features. Conclusion The top caregiver concerns for individuals with RTT and the RTT-related disorders reflect the impact of the primary clinical symptoms of these disorders. This work is critical in the development of meaningful therapies, as optimal therapy should address these concerns. Further, outcome measures to be utilized in clinical trials should assess these clinical issues identified as most concerning by caregivers.
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Affiliation(s)
| | - Timothy A Benke
- University of Colorado School of Medicine: University of Colorado Anschutz Medical Campus School of Medicine
| | | | | | - Lori Silveira
- University of Colorado School of Medicine: University of Colorado Anschutz Medical Campus School of Medicine
| | - Cary Fu
- Vanderbilt University Medical Center
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10
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Panayotis N, Ehinger Y, Felix MS, Roux JC. State-of-the-art therapies for Rett syndrome. Dev Med Child Neurol 2023; 65:162-170. [PMID: 36056801 PMCID: PMC10087176 DOI: 10.1111/dmcn.15383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 07/28/2022] [Accepted: 07/29/2022] [Indexed: 01/04/2023]
Abstract
Rett syndrome (RTT) is an X-linked neurogenetic disorder caused by mutations of the MECP2 (methyl-CpG-binding protein 2) gene. Over two decades of work established MeCP2 as a protein with pivotal roles in the regulation of the epigenome, neuronal physiology, synaptic maintenance, and behaviour. Given the genetic aetiology of RTT and the proof of concept of its reversal in a mouse model, considerable efforts have been made to design therapeutic approaches to re-express MeCP2. By being at the forefront of the development of innovative gene therapies, research on RTT is of paramount importance for the treatment of monogenic neurological diseases. Here we discuss the recent advances and challenges of promising genetic strategies for the treatment of RTT including gene replacement therapies, gene/RNA editing strategies, and reactivation of the silenced X chromosome. WHAT THIS PAPER ADDS: Recent advances shed light on the promises of gene replacement therapy with new vectors designed to control the levels of MeCP2 expression. New developments in DNA/RNA editing approaches or reactivation of the silenced X chromosome open the possibility to re-express the native MeCP2 locus at endogenous levels. Current strategies still face limitations in transduction efficiency and future work is needed to improve brain delivery.
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Affiliation(s)
- Nicolas Panayotis
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel.,Department of Molecular Neuroscience, Weizmann Institute of Science, Rehovot, Israel.,Université Paris Cité, CNRS, Saints-Pères Paris Institute for the Neurosciences, Paris, France
| | - Yann Ehinger
- Department of Neurology, University of California San Francisco, San Francisco, CA, USA
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11
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Erickson KR, Farmer R, Merritt JK, Miletic Lanaghan Z, Does MD, Ramadass K, Landman BA, Cutting LE, Neul JL. Behavioral and brain anatomical analysis of Foxg1 heterozygous mice. PLoS One 2022; 17:e0266861. [PMID: 36223387 PMCID: PMC9555627 DOI: 10.1371/journal.pone.0266861] [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: 03/23/2022] [Accepted: 09/02/2022] [Indexed: 11/06/2022] Open
Abstract
FOXG1 Syndrome (FS) is a devastating neurodevelopmental disorder that is caused by a heterozygous loss-of-function (LOF) mutation of the FOXG1 gene, which encodes a transcriptional regulator important for telencephalic brain development. People with FS have marked developmental delays, impaired ambulation, movement disorders, seizures, and behavior abnormalities including autistic features. Current therapeutic approaches are entirely symptomatic, however the ability to rescue phenotypes in mouse models of other genetic neurodevelopmental disorders such as Rett syndrome, Angelman syndrome, and Phelan-McDermid syndrome by postnatal expression of gene products has led to hope that similar approaches could help modify the disease course in other neurodevelopmental disorders such as FS. While FoxG1 protein function plays a critical role in embryonic brain development, the ongoing adult expression of FoxG1 and behavioral phenotypes that present when FoxG1 function is removed postnatally provides support for opportunity for improvement with postnatal treatment. Here we generated a new mouse allele of Foxg1 that disrupts protein expression and characterized the behavioral and structural brain phenotypes in heterozygous mutant animals. These mutant animals display changes in locomotor behavior, gait, anxiety, social interaction, aggression, and learning and memory compared to littermate controls. Additionally, they have structural brain abnormalities reminiscent of people with FS. This information provides a framework for future studies to evaluate the potential for post-natal expression of FoxG1 to modify the disease course in this severe neurodevelopmental disorder.
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Affiliation(s)
- Kirsty R. Erickson
- Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Rebekah Farmer
- Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Jonathan K. Merritt
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Zeljka Miletic Lanaghan
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Mark D. Does
- Department of Electrical Engineering, Vanderbilt University Nashville, Tennessee, United States of America
| | - Karthik Ramadass
- Department of Electrical Engineering, Vanderbilt University Nashville, Tennessee, United States of America
| | - Bennett A. Landman
- Department of Electrical Engineering, Vanderbilt University Nashville, Tennessee, United States of America
| | - Laurie E. Cutting
- Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Department of Special Education, Peabody College, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Jeffrey L. Neul
- Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Special Education, Peabody College, Vanderbilt University, Nashville, Tennessee, United States of America
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12
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Grimm NB, Lee JT. Selective Xi reactivation and alternative methods to restore MECP2 function in Rett syndrome. Trends Genet 2022; 38:920-943. [PMID: 35248405 PMCID: PMC9915138 DOI: 10.1016/j.tig.2022.01.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 01/15/2022] [Accepted: 01/19/2022] [Indexed: 10/19/2022]
Abstract
The human X-chromosome harbors only 4% of our genome but carries over 20% of genes associated with intellectual disability. Given that they inherit only one X-chromosome, males are more frequently affected by X-linked neurodevelopmental genetic disorders than females. However, despite inheriting two X-chromosomes, females can also be affected because X-chromosome inactivation enables only one of two X-chromosomes to be expressed per cell. For Rett syndrome and similar X-linked disorders affecting females, disease-specific treatments have remained elusive. However, a cure may be found within their own cells because every sick cell carries a healthy copy of the affected gene on the inactive X (Xi). Therefore, selective Xi reactivation may be a viable approach that would address the root cause of various X-linked disorders. Here, we discuss Rett syndrome and compare current approaches in the pharmaceutical pipeline to restore MECP2 function. We then focus on Xi reactivation and review available methods, lessons learned, and future directions.
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Affiliation(s)
- Niklas-Benedikt Grimm
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA; Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, MA, USA; Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Jeannie T Lee
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA; Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
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13
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Exploration of group II metabotropic glutamate receptor modulation in mouse models of Rett syndrome and MECP2 Duplication syndrome. Neuropharmacology 2022; 209:109022. [PMID: 35248529 PMCID: PMC8973998 DOI: 10.1016/j.neuropharm.2022.109022] [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] [Received: 12/20/2021] [Revised: 02/11/2022] [Accepted: 02/27/2022] [Indexed: 01/01/2023]
Abstract
Rett syndrome (RTT) and MECP2 Duplication syndrome (MDS) have opposing molecular origins in relation to expression and function of the transcriptional regulator Methyl-CpG-binding protein 2 (MeCP2). Several clinical and preclinical phenotypes, however, are shared between these disorders. Modulation of MeCP2 levels has recently emerged as a potential treatment option for both of these diseases. However, toxicity concerns remain with these approaches. Here, we focus on pharmacologically modulating the group II metabotropic glutamate receptors (mGlu), mGlu2 and mGlu3, which are two downstream targets of MeCP2 that are bidirectionally affected in expression in RTT patients and mice (Mecp2Null/+) versus an MDS mouse model (MECP2Tg1/o). Mecp2Null/+ and MECP2Tg1/o animals also exhibit contrasting phenotypes in trace fear acquisition, a form of temporal associative learning and memory, with trace fear deficiency observed in Mecp2Null/+ mice and abnormally enhanced trace fear acquisition in MECP2Tg1/o animals. In Mecp2Null/+ mice, treatment with the mGlu2/3 agonist LY379268 reverses the deficit in trace fear acquisition, and mGlu2/3 antagonism with LY341495 normalizes the abnormal trace fear learning and memory phenotype in MECP2Tg1/o mice. Altogether, these data highlight the role of group II mGlu receptors in RTT and MDS and demonstrate that both mGlu2 and mGlu3 may be potential therapeutic targets for these disorders.
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14
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Bassuk AG. Gene therapy for Rett syndrome. GENES, BRAIN, AND BEHAVIOR 2022; 21:e12754. [PMID: 34053173 PMCID: PMC9744469 DOI: 10.1111/gbb.12754] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 05/26/2021] [Indexed: 11/29/2022]
Affiliation(s)
- Alexander G Bassuk
- Pediatrics Child Neurology, Neurology, Neurology, Genetics, Molecular and Cellular Biology, The Iowa Neuroscience Institute (INI), The Medical Scientist Training Program, The University of Iowa, Iowa City, Iowa, USA
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15
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Collins BE, Neul JL. Rett Syndrome and MECP2 Duplication Syndrome: Disorders of MeCP2 Dosage. Neuropsychiatr Dis Treat 2022; 18:2813-2835. [PMID: 36471747 PMCID: PMC9719276 DOI: 10.2147/ndt.s371483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Accepted: 11/14/2022] [Indexed: 11/30/2022] Open
Abstract
Rett syndrome (RTT) is a neurodevelopmental disorder caused predominantly by loss-of-function mutations in the gene Methyl-CpG-binding protein 2 (MECP2), which encodes the MeCP2 protein. RTT is a MECP2-related disorder, along with MECP2 duplication syndrome (MDS), caused by gain-of-function duplications of MECP2. Nearly two decades of research have advanced our knowledge of MeCP2 function in health and disease. The following review will discuss MeCP2 protein function and its dysregulation in the MECP2-related disorders RTT and MDS. This will include a discussion of the genetic underpinnings of these disorders, specifically how sporadic X-chromosome mutations arise and manifest in specific populations. We will then review current diagnostic guidelines and clinical manifestations of RTT and MDS. Next, we will delve into MeCP2 biology, describing the dual landscapes of methylated DNA and its reader MeCP2 across the neuronal genome as well as the function of MeCP2 as a transcriptional modulator. Following this, we will outline common MECP2 mutations and genotype-phenotype correlations in both diseases, with particular focus on mutations associated with relatively mild disease in RTT. We will also summarize decades of disease modeling and resulting molecular, synaptic, and behavioral phenotypes associated with RTT and MDS. Finally, we list several therapeutics in the development pipeline for RTT and MDS and available evidence of their safety and efficacy.
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Affiliation(s)
- Bridget E Collins
- Medical Scientist Training Program, Vanderbilt University, Nashville, TN, USA
| | - Jeffrey L Neul
- Vanderbilt Kennedy Center, Departments of Pediatrics, Pharmacology, and Special Education, Vanderbilt University Medical Center and Vanderbilt University, Nashville, TN, USA
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16
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Merritt JK, Collins BE, Erickson KR, Dong H, Neul JL. Pharmacological read-through of R294X Mecp2 in a novel mouse model of Rett syndrome. Hum Mol Genet 2021; 29:2461-2470. [PMID: 32469049 DOI: 10.1093/hmg/ddaa102] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 05/21/2020] [Accepted: 05/27/2020] [Indexed: 11/14/2022] Open
Abstract
Rett syndrome (RTT) is a neurodevelopmental disorder primarily caused by mutations in Methyl-CpG-binding Protein 2 (MECP2). More than 35% of affected individuals have nonsense mutations in MECP2. For these individuals, nonsense suppression has been suggested as a possible therapeutic approach. To assess the viability of this strategy, we created and characterized a mouse model with the common p.R294X mutation introduced into the endogenous Mecp2 locus (Mecp2R294X). Mecp2R294X mice exhibit phenotypic abnormalities similar to those seen in complete null mouse models; however, these occur at a later time point consistent with the reduced phenotypic severity seen in affected individuals containing this specific mutation. The delayed onset of severe phenotypes is likely due to the presence of truncated MeCP2 in Mecp2R294X mice. Supplying the MECP2 transgene in Mecp2R294X mice rescued phenotypic abnormalities including early death and demonstrated that the presence of truncated MeCP2 in these mice does not interfere with wild-type MeCP2. In vitro treatment of a cell line derived from Mecp2R294X mice with the nonsense suppression agent G418 resulted in full-length MeCP2 protein production, demonstrating feasibility of this therapeutic approach. Intraperitoneal administration of G418 in Mecp2R294X mice was sufficient to elicit full-length MeCP2 protein expression in peripheral tissues. Finally, intracranial ventricular injection of G418 in Mecp2R294X mice induced expression of full-length MeCP2 protein in the mouse brain. These experiments demonstrate that translational read-through drugs are able to suppress the Mecp2 p.R294X mutation in vivo and provide a proof of concept for future preclinical studies of nonsense suppression agents in RTT.
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Affiliation(s)
- Jonathan K Merritt
- Department of Neurosciences, University of California at San Diego, La Jolla, CA 92093, USA.,Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37212, USA.,Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, TN 37203, USA
| | - Bridget E Collins
- Medical Scientist Training Program, Vanderbilt University, Nashville, TN 37232, USA.,Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37232, USA
| | - Kirsty R Erickson
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37212, USA.,Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, TN 37203, USA
| | - Hongwei Dong
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37212, USA.,Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, TN 37203, USA
| | - Jeffrey L Neul
- Department of Neurosciences, University of California at San Diego, La Jolla, CA 92093, USA.,Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37212, USA.,Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, TN 37203, USA
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17
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Ash RT, Buffington SA, Park J, Suter B, Costa-Mattioli M, Zoghbi HY, Smirnakis SM. Inhibition of Elevated Ras-MAPK Signaling Normalizes Enhanced Motor Learning and Excessive Clustered Dendritic Spine Stabilization in the MECP2-Duplication Syndrome Mouse Model of Autism. eNeuro 2021; 8:ENEURO.0056-21.2021. [PMID: 34021030 PMCID: PMC8260274 DOI: 10.1523/eneuro.0056-21.2021] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 04/06/2021] [Accepted: 04/07/2021] [Indexed: 12/26/2022] Open
Abstract
The inflexible repetitive behaviors and "insistence on sameness" seen in autism imply a defect in neural processes controlling the balance between stability and plasticity of synaptic connections in the brain. It has been proposed that abnormalities in the Ras-ERK/MAPK pathway, a key plasticity-related cell signaling pathway known to drive consolidation of clustered synaptic connections, underlie altered learning phenotypes in autism. However, a link between altered Ras-ERK signaling and clustered dendritic spine plasticity has yet to be explored in an autism animal model in vivo The formation and stabilization of dendritic spine clusters is abnormally increased in the MECP2-duplication syndrome mouse model of syndromic autism, suggesting that ERK signaling may be increased. Here, we show that the Ras-ERK pathway is indeed hyperactive following motor training in MECP2-duplication mouse motor cortex. Pharmacological inhibition of ERK signaling normalizes the excessive clustered spine stabilization and enhanced motor learning behavior in MECP2-duplication mice. We conclude that hyperactive ERK signaling may contribute to abnormal clustered dendritic spine consolidation and motor learning in this model of syndromic autism.
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Affiliation(s)
- Ryan Thomas Ash
- Department of Psychiatry and Behavioral Sciences, Stanford University, CA 94305
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030
- Medical Scientist Training Program, Baylor College of Medicine, Houston, TX 77030
- Department of Neurology, Brigham and Women's Hospital and Jamaica Plain Veterans Administration Hospital, Harvard Medical School, Boston, MA 02115
| | - Shelly Alexandra Buffington
- Memory and Brain Research Center, Baylor College of Medicine, Houston, TX 77030
- Department of Neuroscience, Cell Biology, and Anatomy, University of Texas Medical Branch, Galveston, TX 77555
| | - Jiyoung Park
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030
- Department of Neurology, Brigham and Women's Hospital and Jamaica Plain Veterans Administration Hospital, Harvard Medical School, Boston, MA 02115
| | - Bernhard Suter
- Department of Neurology, Brigham and Women's Hospital and Jamaica Plain Veterans Administration Hospital, Harvard Medical School, Boston, MA 02115
- Department of Pediatrics, Texas Children's Hospital and Baylor College of Medicine, Houston, TX 77030
| | - Mauro Costa-Mattioli
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030
- Memory and Brain Research Center, Baylor College of Medicine, Houston, TX 77030
| | - Huda Yaya Zoghbi
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030
- Department of Pediatrics, Texas Children's Hospital and Baylor College of Medicine, Houston, TX 77030
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX 77030
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX 77030
| | - Stelios Manolis Smirnakis
- Department of Neurology, Brigham and Women's Hospital and Jamaica Plain Veterans Administration Hospital, Harvard Medical School, Boston, MA 02115
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18
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Kuang L, Hashimoto K, Huang EJ, Gentry MS, Zhu H. Frontotemporal dementia non-sense mutation of progranulin rescued by aminoglycosides. Hum Mol Genet 2021; 29:624-634. [PMID: 31913476 DOI: 10.1093/hmg/ddz280] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 10/22/2019] [Accepted: 11/19/2019] [Indexed: 02/06/2023] Open
Abstract
Frontotemporal dementia (FTD) is an early onset dementia characterized by progressive atrophy of the frontal and/or temporal lobes. FTD is highly heritable with mutations in progranulin accounting for 5-26% of cases in different populations. Progranulin is involved in endocytosis, secretion and lysosomal processes, but its functions under physiological and pathological conditions remains to be defined. Many FTD-causing non-sense progranulin mutations contain a premature termination codon (PTC), thus progranulin haploinsufficiency has been proposed as a major disease mechanism. Currently, there is no effective FTD treatment or therapy. Aminoglycosides are a class of antibiotics that possess a less-known function to induce eukaryotic ribosomal readthrough of PTCs to produce a full-length protein. The aminoglycoside-induced readthrough strategy has been utilized to treat multiple human diseases caused by PTCs. In this study, we tested the only clinically approved readthrough small molecule PTC124 and 11 aminoglycosides in a cell culture system on four PTCs responsible for FTD or a related neurodegenerative disease amyotrophic lateral sclerosis. We found that the aminoglycosides G418 and gentamicin rescued the expression of the progranulin R493X mutation. G418 was more effective than gentamicin (~50% rescue versus <10%), and the effect was dose- and time-dependent. The progranulin readthrough protein displayed similar subcellular localization as the wild-type progranulin protein. These data provide an exciting proof-of-concept that aminoglycosides or other readthrough-promoting compounds are a therapeutic avenue for familial FTD caused by progranulin PTC mutations.
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Affiliation(s)
- Lisha Kuang
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY 40536, USA
| | - Kei Hashimoto
- Department of Pathology, University of California, San Francisco, CA 94143, USA
| | - Eric J Huang
- Department of Pathology, University of California, San Francisco, CA 94143, USA
| | - Matthew S Gentry
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY 40536, USA
| | - Haining Zhu
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY 40536, USA.,Lexington VA Medical Center, Research & Development, Lexington, KY 40502, USA
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19
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Vermudez SAD, Gogliotti RG, Arthur B, Buch A, Morales C, Moxley Y, Rajpal H, Conn PJ, Niswender CM. Profiling beneficial and potential adverse effects of MeCP2 overexpression in a hypomorphic Rett syndrome mouse model. GENES, BRAIN, AND BEHAVIOR 2021; 21:e12752. [PMID: 34002468 PMCID: PMC8599502 DOI: 10.1111/gbb.12752] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 05/15/2021] [Accepted: 05/16/2021] [Indexed: 01/03/2023]
Abstract
De novo loss-of-function mutations in methyl-CpG-binding protein 2 (MeCP2) lead to the neurodevelopmental disorder Rett syndrome (RTT). Despite promising results from strategies aimed at increasing MeCP2 levels, additional studies exploring how hypomorphic MeCP2 mutations impact the therapeutic window are needed. Here, we investigated the consequences of genetically introducing a wild-type MECP2 transgene in the Mecp2 R133C mouse model of RTT. The MECP2 transgene reversed the majority of RTT-like phenotypes exhibited by male and female Mecp2 R133C mice. However, three core symptom domains were adversely affected in female Mecp2R133C/+ animals; these phenotypes resemble those observed in disease contexts of excess MeCP2. Parallel control experiments in Mecp2Null/+ mice linked these adverse effects to the hypomorphic R133C mutation. Collectively, these data provide evidence regarding the safety and efficacy of genetically overexpressing functional MeCP2 in Mecp2 R133C mice and suggest that personalized approaches may warrant consideration for the clinical assessment of MeCP2-targeted therapies.
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Affiliation(s)
- Sheryl Anne D. Vermudez
- Department of Pharmacology and Warren Center for Neuroscience Drug DiscoveryVanderbilt UniversityNashvilleTennesseeUSA
| | - Rocco G. Gogliotti
- Department of Molecular Pharmacology and NeuroscienceLoyola University ChicagoChicagoIllinoisUSA
| | - Bright Arthur
- Department of Pharmacology and Warren Center for Neuroscience Drug DiscoveryVanderbilt UniversityNashvilleTennesseeUSA
| | - Aditi Buch
- Department of Pharmacology and Warren Center for Neuroscience Drug DiscoveryVanderbilt UniversityNashvilleTennesseeUSA
| | - Clarissa Morales
- Department of Pharmacology and Warren Center for Neuroscience Drug DiscoveryVanderbilt UniversityNashvilleTennesseeUSA
| | - Yuta Moxley
- Department of Pharmacology and Warren Center for Neuroscience Drug DiscoveryVanderbilt UniversityNashvilleTennesseeUSA
| | - Hemangi Rajpal
- Department of Pharmacology and Warren Center for Neuroscience Drug DiscoveryVanderbilt UniversityNashvilleTennesseeUSA
| | - P. Jeffrey Conn
- Department of Pharmacology and Warren Center for Neuroscience Drug DiscoveryVanderbilt UniversityNashvilleTennesseeUSA,Vanderbilt Kennedy CenterVanderbilt UniversityNashvilleTennesseeUSA,Vanderbilt Institute of Chemical BiologyVanderbilt UniversityNashvilleTennesseeUSA
| | - Colleen M. Niswender
- Department of Pharmacology and Warren Center for Neuroscience Drug DiscoveryVanderbilt UniversityNashvilleTennesseeUSA,Vanderbilt Kennedy CenterVanderbilt UniversityNashvilleTennesseeUSA,Vanderbilt Institute of Chemical BiologyVanderbilt UniversityNashvilleTennesseeUSA
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20
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Collins BE, Merritt JK, Erickson KR, Neul JL. Safety and efficacy of genetic MECP2 supplementation in the R294X mouse model of Rett syndrome. GENES, BRAIN, AND BEHAVIOR 2021; 21:e12739. [PMID: 33942492 PMCID: PMC8563491 DOI: 10.1111/gbb.12739] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 04/29/2021] [Accepted: 05/01/2021] [Indexed: 01/03/2023]
Abstract
Rett syndrome is a neurodevelopmental disorder caused predominantly by loss-of-function mutations in MECP2, encoding transcriptional modulator methyl-CpG-binding protein 2 (MeCP2). Although no disease-modifying therapies exist at this time, some proposed therapeutic strategies aim to supplement the mutant allele with a wild-type allele producing typical levels of functional MeCP2, such as gene therapy. Because MECP2 is a dosage-sensitive gene, with both loss and gain of function causing disease, these approaches must achieve a narrow therapeutic window to be both safe and effective. While MeCP2 supplementation rescues RTT-like phenotypes in mouse models, the tolerable threshold of MeCP2 is not clear, particularly for partial loss-of-function mutations. We assessed the safety of genetically supplementing full-length human MeCP2 in the context of the R294X allele, a common partial loss-of-function mutation retaining DNA-binding capacity. We assessed the potential for adverse effects from MeCP2 supplementation of a partial loss-of-function mutant and the potential for dominant negative interactions between mutant and full-length MeCP2. In male hemizygous R294X mice, MeCP2 supplementation rescued RTT-like behavioral phenotypes and did not elicit behavioral evidence of excess MeCP2. In female heterozygous R294X mice, RTT-specific phenotypes were similarly rescued. However, MeCP2 supplementation led to evidence of excess MeCP2 activity in a motor coordination assay, suggesting that the underlying motor circuitry is particularly sensitive to MeCP2 dosage in females. These results show that genetic supplementation of full-length MeCP2 is safe in males and largely so females. However, careful consideration of risk for adverse motor effects may be warranted for girls and women with RTT.
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Affiliation(s)
| | - Jonathan K. Merritt
- Department of PediatricsVanderbilt University Medical CenterNashvilleTennesseeUSA
| | - Kirsty R. Erickson
- Department of PediatricsVanderbilt University Medical CenterNashvilleTennesseeUSA
| | - Jeffrey L. Neul
- Vanderbilt Kennedy Center, Departments of Pediatrics, Pharmacology, and Special EducationVanderbilt University Medical Center and Vanderbilt UniversityNashvilleTennesseeUSA
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21
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Reviewing Evidence for the Relationship of EEG Abnormalities and RTT Phenotype Paralleled by Insights from Animal Studies. Int J Mol Sci 2021; 22:ijms22105308. [PMID: 34069993 PMCID: PMC8157853 DOI: 10.3390/ijms22105308] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 05/09/2021] [Accepted: 05/12/2021] [Indexed: 12/29/2022] Open
Abstract
Rett syndrome (RTT) is a rare neurodevelopmental disorder that is usually caused by mutations of the MECP2 gene. Patients with RTT suffer from severe deficits in motor, perceptual and cognitive domains. Electroencephalogram (EEG) has provided useful information to clinicians and scientists, from the very first descriptions of RTT, and yet no reliable neurophysiological biomarkers related to the pathophysiology of the disorder or symptom severity have been identified to date. To identify consistently observed and potentially informative EEG characteristics of RTT pathophysiology, and ascertain areas most worthy of further systematic investigation, here we review the literature for EEG abnormalities reported in patients with RTT and in its disease models. While pointing to some promising potential EEG biomarkers of RTT, our review identify areas of need to realize the potential of EEG including (1) quantitative investigation of promising clinical-EEG observations in RTT, e.g., shift of mu rhythm frequency and EEG during sleep; (2) closer alignment of approaches between patients with RTT and its animal models to strengthen the translational significance of the work (e.g., EEG measurements and behavioral states); (3) establishment of large-scale consortium research, to provide adequate Ns to investigate age and genotype effects.
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22
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Gomathi M, Padmapriya S, Balachandar V. Drug Studies on Rett Syndrome: From Bench to Bedside. J Autism Dev Disord 2020; 50:2740-2764. [PMID: 32016693 DOI: 10.1007/s10803-020-04381-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Drug studies on Rett syndrome (RTT) have drastically increased over the past few decades. This review aims to provide master data on bench-to-bedside drug studies involving RTT. A comprehensive literature review was performed by searching in PUBMED, MEDLINE and Google Scholar, international, national and regional clinical trial registries and pharmaceutical companies using the keywords "Rett syndrome treatment and/or drug or compound or molecule". Seventy drugs were investigated in non-clinical (N = 65 animal/cell line-based studies; N = 5 iPSC-based study) and clinical trials (N = 34) for ameliorating the symptoms of RTT. Though there is good progress in both clinical and non-clinical studies, none of these drugs entered phase III/IV for being launched as a therapeutic agent for RTT.
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Affiliation(s)
- Mohan Gomathi
- Human Molecular Genetics and Stem Cell Laboratory, Department of Human Genetics and Molecular Biology, Bharathiar University, Coimbatore, Tamil Nadu, 641046, India
| | | | - Vellingiri Balachandar
- Human Molecular Genetics and Stem Cell Laboratory, Department of Human Genetics and Molecular Biology, Bharathiar University, Coimbatore, Tamil Nadu, 641046, India.
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Ward CS, Huang TW, Herrera JA, Samaco RC, McGraw CM, Parra DE, Arvide EM, Ito-Ishida A, Meng X, Ure K, Zoghbi HY, Neul JL. Loss of MeCP2 Function Across Several Neuronal Populations Impairs Breathing Response to Acute Hypoxia. Front Neurol 2020; 11:593554. [PMID: 33193060 PMCID: PMC7662121 DOI: 10.3389/fneur.2020.593554] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 10/06/2020] [Indexed: 11/26/2022] Open
Abstract
Rett Syndrome (RTT) is a neurodevelopmental disorder caused by loss of function of the transcriptional regulator Methyl-CpG-Binding Protein 2 (MeCP2). In addition to the characteristic loss of hand function and spoken language after the first year of life, people with RTT also have a variety of physiological and autonomic abnormalities including disrupted breathing rhythms characterized by bouts of hyperventilation and an increased frequency of apnea. These breathing abnormalities, that likely involve alterations in both the circuitry underlying respiratory pace making and those underlying breathing response to environmental stimuli, may underlie the sudden unexpected death seen in a significant fraction of people with RTT. In fact, mice lacking MeCP2 function exhibit abnormal breathing rate response to acute hypoxia and maintain a persistently elevated breathing rate rather than showing typical hypoxic ventilatory decline that can be observed among their wild-type littermates. Using genetic and pharmacological tools to better understand the course of this abnormal hypoxic breathing rate response and the neurons driving it, we learned that the abnormal hypoxic breathing response is acquired as the animals mature, and that MeCP2 function is required within excitatory, inhibitory, and modulatory populations for a normal hypoxic breathing rate response. Furthermore, mice lacking MeCP2 exhibit decreased hypoxia-induced neuronal activity within the nucleus tractus solitarius of the dorsal medulla. Overall, these data provide insight into the neurons driving the circuit dysfunction that leads to breathing abnormalities upon loss of MeCP2. The discovery that combined dysfunction across multiple neuronal populations contributes to breathing dysfunction may provide insight into sudden unexpected death in RTT.
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Affiliation(s)
- Christopher S. Ward
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, United States
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, United States
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States
| | - Teng-Wei Huang
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, United States
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX, United States
| | - Jose A. Herrera
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, United States
- Interdepartmental Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, TX, United States
| | - Rodney C. Samaco
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, United States
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States
| | - Christopher M. McGraw
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, United States
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX, United States
| | - Diana E. Parra
- Department of Pediatrics, Baylor College of Medicine, Houston, TX, United States
| | - E. Melissa Arvide
- Department of Pediatrics, Baylor College of Medicine, Houston, TX, United States
| | - Aya Ito-Ishida
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, United States
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States
| | - Xiangling Meng
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, United States
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, United States
| | - Kerstin Ure
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, United States
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States
| | - Huda Y. Zoghbi
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, United States
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX, United States
- Interdepartmental Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, TX, United States
- Department of Pediatrics, Baylor College of Medicine, Houston, TX, United States
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, United States
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX, United States
| | - Jeffrey L. Neul
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, United States
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX, United States
- Interdepartmental Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, TX, United States
- Department of Pediatrics, Baylor College of Medicine, Houston, TX, United States
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, United States
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24
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Dong HW, Erickson K, Lee JR, Merritt J, Fu C, Neul JL. Detection of neurophysiological features in female R255X MeCP2 mutation mice. Neurobiol Dis 2020; 145:105083. [PMID: 32927061 PMCID: PMC7572861 DOI: 10.1016/j.nbd.2020.105083] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 08/11/2020] [Accepted: 09/08/2020] [Indexed: 02/07/2023] Open
Abstract
Rett syndrome (RTT) is a severe neurodevelopmental disorder (NDD) that is nearly always caused by loss of function mutations in Methyl-CpG-binding Protein 2 (MECP2) and shares many clinical features with other NDD. Genetic restoration of Mecp2 in symptomatic mice lacking MeCP2 expression can reverse symptoms, providing hope that disease modifying therapies can be identified for RTT. Effective and rapid clinical trial completion relies on well-defined clinical outcome measures and robust biomarkers of treatment responses. Studies on other NDD have found evidence of differences in neurophysiological measures that correlate with disease severity. However, currently there are no well-validated biomarkers in RTT to predict disease prognosis or treatment responses. To address this, we characterized neurophysiological features in a mouse model of RTT containing a knock-in nonsense mutation (p.R255X) in the Mecp2 locus. We found a variety of changes in heterozygous female Mecp2R255X/X mice including age-related changes in sleep/wake architecture, alterations in baseline EEG power, increased incidence of spontaneous epileptiform discharges, and changes in auditory evoked potentials. Furthermore, we identified association of some neurophysiological features with disease severity. These findings provide a set of potential non-invasive and translatable biomarkers that can be utilized in preclinical therapy trials in animal models of RTT and eventually within the context of clinical trials.
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Affiliation(s)
- Hong-Wei Dong
- Department of Pediatrics, Division of Neurology, Vanderbilt University Medical Center, Nashville, TN 37212, USA; Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, TN 37203, USA.
| | - Kirsty Erickson
- Department of Pediatrics, Division of Neurology, Vanderbilt University Medical Center, Nashville, TN 37212, USA; Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, TN 37203, USA.
| | - Jessica R Lee
- Department of Pediatrics, Division of Neurology, Vanderbilt University Medical Center, Nashville, TN 37212, USA; Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, TN 37203, USA.
| | - Jonathan Merritt
- Department of Pediatrics, Division of Neurology, Vanderbilt University Medical Center, Nashville, TN 37212, USA; Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, TN 37203, USA.
| | - Cary Fu
- Department of Pediatrics, Division of Neurology, Vanderbilt University Medical Center, Nashville, TN 37212, USA; Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, TN 37203, USA.
| | - Jeffrey L Neul
- Department of Pediatrics, Division of Neurology, Vanderbilt University Medical Center, Nashville, TN 37212, USA; Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, TN 37203, USA.
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25
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MeCP2 and Chromatin Compartmentalization. Cells 2020; 9:cells9040878. [PMID: 32260176 PMCID: PMC7226738 DOI: 10.3390/cells9040878] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 03/27/2020] [Accepted: 04/01/2020] [Indexed: 12/24/2022] Open
Abstract
Methyl-CpG binding protein 2 (MeCP2) is a multifunctional epigenetic reader playing a role in transcriptional regulation and chromatin structure, which was linked to Rett syndrome in humans. Here, we focus on its isoforms and functional domains, interactions, modifications and mutations found in Rett patients. Finally, we address how these properties regulate and mediate the ability of MeCP2 to orchestrate chromatin compartmentalization and higher order genome architecture.
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Tillotson R, Bird A. The Molecular Basis of MeCP2 Function in the Brain. J Mol Biol 2020; 432:1602-1623. [PMID: 31629770 DOI: 10.1016/j.jmb.2019.10.004] [Citation(s) in RCA: 85] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 10/04/2019] [Accepted: 10/05/2019] [Indexed: 12/14/2022]
Abstract
MeCP2 is a reader of the DNA methylome that occupies a large proportion of the genome due to its high abundance and the frequency of its target sites. It has been the subject of extensive study because of its link with 'MECP2-related disorders', of which Rett syndrome is the most prevalent. This review integrates evidence from patient mutation data with results of experimental studies using mouse models, cell lines and in vitro systems to critically evaluate our understanding of MeCP2 protein function. Recent evidence challenges the idea that MeCP2 is a multifunctional hub that integrates diverse processes to underpin neuronal function, suggesting instead that its primary role is to recruit the NCoR1/2 co-repressor complex to methylated sites in the genome, leading to dampening of gene expression.
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Affiliation(s)
- Rebekah Tillotson
- Genetics and Genome Biology Program, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, ON M5G 0A4, Canada; Medical Research Council (MRC) Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Headington, Oxford, OX3 9DS, UK
| | - Adrian Bird
- Wellcome Centre for Cell Biology, University of Edinburgh, The Michael Swann Building, King's Buildings, Max Born Crescent, Edinburgh, EH9 3BF, UK.
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27
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Sysoeva OV, Smirnov K, Stroganova TA. Sensory evoked potentials in patients with Rett syndrome through the lens of animal studies: Systematic review. Clin Neurophysiol 2019; 131:213-224. [PMID: 31812082 DOI: 10.1016/j.clinph.2019.11.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 11/07/2019] [Accepted: 11/11/2019] [Indexed: 01/04/2023]
Abstract
OBJECTIVE Systematically review the abnormalities in event related potential (ERP) recorded in Rett Syndrome (RTT) patients and animals in search of translational biomarkers of deficits related to the particular neurophysiological processes of known genetic origin (MECP2 mutations). METHODS Pubmed, ISI Web of Knowledge and BIORXIV were searched for the relevant articles according to PRISMA standards. RESULTS ERP components are generally delayed across all sensory modalities both in RTT patients and its animal model, while findings on ERPs amplitude strongly depend on stimulus properties and presentation rate. Studies on RTT animal models uncovered the abnormalities in the excitatory and inhibitory transmission as critical mechanisms underlying the ERPs changes, but showed that even similar ERP alterations in auditory and visual domains have a diverse neural basis. A range of novel approaches has been developed in animal studies bringing along the meaningful neurophysiological interpretation of ERP measures in RTT patients. CONCLUSIONS While there is a clear evidence for sensory ERPs abnormalities in RTT, to further advance the field there is a need in a large-scale ERP studies with the functionally-relevant experimental paradigms. SIGNIFICANCE The review provides insights into domain-specific neural basis of the ERP abnormalities and promotes clinical application of the ERP measures as the non-invasive functional biomarkers of RTT pathophysiology.
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Affiliation(s)
- Olga V Sysoeva
- The Cognitive Neurophysiology Laboratory, Department of Pediatrics, Albert Einstein College of Medicine & Montefiore Medical Center, Bronx, New York, USA; The Cognitive Neurophysiology Laboratory, Ernest J. Del Monte Institute for Neuroscience, Department of Neuroscience, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA; The Laboratory of Human Higher Nervous Activity, Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia.
| | - Kirill Smirnov
- Department of Neuroontogenesis, Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Science, Moscow, Russia.
| | - Tatiana A Stroganova
- Center for Neurocognitive Research (MEG-Center), Moscow State University of Psychology and Education (MSUPE), Moscow, Russia; Autism Research Laboratory, Moscow State University of Psychology and Education (MSUPE), Moscow, Russia.
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28
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Yang H, Li K, Han S, Zhou A, Zhou ZJ. Leveraging the genetic basis of Rett syndrome to ascertain pathophysiology. Neurobiol Learn Mem 2019; 165:106961. [PMID: 30447288 PMCID: PMC6635128 DOI: 10.1016/j.nlm.2018.11.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 09/18/2018] [Accepted: 11/14/2018] [Indexed: 10/27/2022]
Abstract
Mutations in the methyl-CpG binding protein 2 (MECP2) gene cause Rett syndrome (RTT), a progressive X-linked neurological disorder characterized by loss of developmental milestones, intellectual disability and breathing abnormality. Despite being a monogenic disorder, the pathogenic mechanisms by which mutations in MeCP2 impair neuronal function and underlie the RTT symptoms have been challenging to elucidate. The seemingly simple genetic root and the availability of genetic data from RTT patients have led to the generation and characterization of a series of mouse models recapitulating RTT-associated genetic mutations. This review focuses on the studies of RTT mouse models and describe newly obtained pathogenic insights from these studies. We also highlight the potential of studying pathophysiology using genetics-based modeling approaches in rodents and suggest a future direction to tackle the pathophysiology of intellectual disability with known or complex genetic causes.
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Affiliation(s)
- Hua Yang
- Qingdao Jiaozhou Central Hospital, Jiaozhou City, Shandong Province 266300, China
| | - Kequan Li
- Qingdao Jiaozhou Central Hospital, Jiaozhou City, Shandong Province 266300, China
| | - Song Han
- Jiaozhou People's Hospital, Jiaozhou City, Shandong Province 266300, China
| | - Ailing Zhou
- Jiaozhou People's Hospital, Jiaozhou City, Shandong Province 266300, China
| | - Zhaolan Joe Zhou
- Department of Genetics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA.
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29
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Robinson HA, Pozzo-Miller L. The role of MeCP2 in learning and memory. ACTA ACUST UNITED AC 2019; 26:343-350. [PMID: 31416907 PMCID: PMC6699413 DOI: 10.1101/lm.048876.118] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 05/21/2019] [Indexed: 01/31/2023]
Abstract
Gene transcription is a crucial step in the sequence of molecular, synaptic, cellular, and systems mechanisms underlying learning and memory. Here, we review the experimental evidence demonstrating that alterations in the levels and functionality of the methylated DNA-binding transcriptional regulator MeCP2 are implicated in the learning and memory deficits present in mouse models of Rett syndrome and MECP2 duplication syndrome. The significant impact that MeCP2 has on gene transcription through a variety of mechanisms, combined with well-defined models of learning and memory, make MeCP2 an excellent candidate to exemplify the role of gene transcription in learning and memory. Together, these studies have strengthened the concept that precise control of activity-dependent gene transcription is a fundamental mechanism that ensures long-term adaptive behaviors necessary for the survival of individuals interacting with their congeners in an ever-changing environment.
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Affiliation(s)
- Holly A Robinson
- Department of Neurobiology, The University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
| | - Lucas Pozzo-Miller
- Department of Neurobiology, The University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
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30
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Cosentino L, Vigli D, Franchi F, Laviola G, De Filippis B. Rett syndrome before regression: A time window of overlooked opportunities for diagnosis and intervention. Neurosci Biobehav Rev 2019; 107:115-135. [PMID: 31108160 DOI: 10.1016/j.neubiorev.2019.05.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 05/10/2019] [Accepted: 05/15/2019] [Indexed: 11/29/2022]
Abstract
Rett syndrome (RTT) is a rare neurological disorder primarily affecting females, causing severe cognitive, social, motor and physiological impairments for which no cure currently exists. RTT clinical diagnosis is based on the peculiar progression of the disease, since patients show an apparently normal initial development with a subsequent sudden regression at around 2 years of age. Accumulating evidences are rising doubts regarding the absence of early impairments, hence questioning the concept of regression. We reviewed the published literature addressing the pre-symptomatic stage of the disease in both patients and animal models with a particular focus on behavioral, physiological and brain abnormalities. The emerging picture delineates subtle, but reliable impairments that precede the onset of overt symptoms whose bases are likely set up already during embryogenesis. Some of the outlined alterations appear transient, suggesting compensatory mechanisms to occur in the course of development. There is urgent need for more systematic developmental analyses able to detect early pathological markers to be used as diagnostic tools and precocious targets of time-specific interventions.
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Affiliation(s)
- Livia Cosentino
- Center for Behavioral Sciences and Mental Health, Istituto Superiore di Sanità, Viale Regina Elena, 299, 00161 Rome, Italy
| | - Daniele Vigli
- Center for Behavioral Sciences and Mental Health, Istituto Superiore di Sanità, Viale Regina Elena, 299, 00161 Rome, Italy
| | - Francesca Franchi
- Center for Behavioral Sciences and Mental Health, Istituto Superiore di Sanità, Viale Regina Elena, 299, 00161 Rome, Italy
| | - Giovanni Laviola
- Center for Behavioral Sciences and Mental Health, Istituto Superiore di Sanità, Viale Regina Elena, 299, 00161 Rome, Italy
| | - Bianca De Filippis
- Center for Behavioral Sciences and Mental Health, Istituto Superiore di Sanità, Viale Regina Elena, 299, 00161 Rome, Italy.
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31
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Guy J, Alexander-Howden B, FitzPatrick L, DeSousa D, Koerner MV, Selfridge J, Bird A. A mutation-led search for novel functional domains in MeCP2. Hum Mol Genet 2019; 27:2531-2545. [PMID: 29718204 PMCID: PMC6030874 DOI: 10.1093/hmg/ddy159] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 04/26/2018] [Indexed: 12/15/2022] Open
Abstract
Most missense mutations causing Rett syndrome (RTT) affect domains of MeCP2 that have been shown to either bind methylated DNA or interact with a transcriptional co-repressor complex. Several mutations, however, including the C-terminal truncations that account for ∼10% of cases, fall outside these characterized domains. We studied the molecular consequences of four of these ‘non-canonical’ mutations in cultured neurons and mice to see if they reveal additional essential domains without affecting known properties of MeCP2. The results show that the mutations partially or strongly deplete the protein and also in some cases interfere with co-repressor recruitment. These mutations therefore impact the activity of known functional domains and do not invoke new molecular causes of RTT. The finding that a stable C-terminal truncation does not compromise MeCP2 function raises the possibility that small molecules which stabilize these mutant proteins may be of therapeutic value.
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Affiliation(s)
- Jacky Guy
- The Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh, UK
| | | | - Laura FitzPatrick
- The Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh, UK
| | - Dina DeSousa
- The Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh, UK
| | - Martha V Koerner
- The Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh, UK
| | - Jim Selfridge
- The Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh, UK
| | - Adrian Bird
- The Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh, UK
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32
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Treating Rett syndrome: from mouse models to human therapies. Mamm Genome 2019; 30:90-110. [PMID: 30820643 PMCID: PMC6606665 DOI: 10.1007/s00335-019-09793-5] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 02/09/2019] [Indexed: 02/06/2023]
Abstract
Rare diseases are very difficult to study mechanistically and to develop therapies for because of the scarcity of patients. Here, the rare neuro-metabolic disorder Rett syndrome (RTT) is discussed as a prototype for precision medicine, demonstrating how mouse models have led to an understanding of the development of symptoms. RTT is caused by mutations in the X-linked gene methyl-CpG-binding protein 2 (MECP2). Mecp2-mutant mice are being used in preclinical studies that target the MECP2 gene directly, or its downstream pathways. Importantly, this work may improve the health of RTT patients. Clinical presentation may vary widely among individuals based on their mutation, but also because of the degree of X chromosome inactivation and the presence of modifier genes. Because it is a complex disorder involving many organ systems, it is likely that recovery of RTT patients will involve a combination of treatments. Precision medicine is warranted to provide the best efficacy to individually treat RTT patients.
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Müller M. Disturbed redox homeostasis and oxidative stress: Potential players in the developmental regression in Rett syndrome. Neurosci Biobehav Rev 2019; 98:154-163. [PMID: 30639673 DOI: 10.1016/j.neubiorev.2018.12.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 11/30/2018] [Accepted: 12/06/2018] [Indexed: 12/16/2022]
Abstract
Rett syndrome (RTT) is a neurodevelopmental disorder affecting mostly girls. A seemingly normal initial development is followed by developmental stagnation and regression, leading to severe mental impairment with autistic features, motor dysfunction, irregular breathing and epilepsy. Currently, a cure does not exist. Due to the close association of RTT with mitochondrial alterations, cellular redox-impairment and oxidative stress, compounds stabilizing mitochondrial function, cellular redox-homeostasis, and oxidant detoxification are increasingly considered as treatment concepts. Indeed, antioxidants and free-radical scavengers ameliorate certain aspects of the complex and severe clinical presentation of RTT. To further evaluate these strategies, reliable biosensors are needed to quantify redox-conditions in brain and peripheral organs of mouse models or in patient-derived cells. Genetically-encoded redox-sensors meet these requirements. Expressed in transgenic mouse-models such as our unique Rett-redox indicator mice, they will report for any cell type desired the severity of oxidant stress throughout the various disease stages of RTT. Furthermore, these sensors will be crucial to evaluate in vitro and in vivo the outcome of mitochondria- and redox-balance targeted treatments.
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Affiliation(s)
- Michael Müller
- Georg-August-Universität Göttingen, Universitätsmedizin Göttingen, Germany; Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Humboldtallee 23, D-37073 Göttingen, Germany; Zentrum Physiologie und Pathophysiologie, Institut für Neuro-und Sinnesphysiologie, Humboldtallee 23, D-37073 Göttingen, Germany.
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34
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Abstract
Elucidating the functions of a particular gene is paramount to the understanding of how its dysfunction contributes to disease. This is especially important when the gene is implicated in multiple different disorders. One such gene is methyl-CpG-binding protein 2 (MECP2), which has been most prominently associated with the neurodevelopmental disorder Rett syndrome, as well as major neuropsychiatric disorders such as autism and schizophrenia. Being initially identified as a transcriptional regulator that modulates gene expression and subsequently also shown to be involved in other molecular events, dysfunction of the MeCP2 protein has the potential to affect many cellular processes. In this chapter, we will briefly review the functions of the MeCP2 protein and how its mutations are implicated in Rett syndrome and other neuropsychiatric disorders. We will further discuss about the mouse models that have been generated to specifically dissect the function of MeCP2 in different cell types and brain regions. It is envisioned that such thorough and targeted examination of MeCP2 functions can aid in enlightening the role that it plays in normal and dysfunctional physiological systems.
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Affiliation(s)
- Eunice W M Chin
- Neuroscience and Mental Health Faculty, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Eyleen L K Goh
- Neuroscience and Mental Health Faculty, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore.
- Department of Research, National Neuroscience Institute, Singapore, Singapore.
- Neuroscience Academic Clinical Programme, Singhealth Duke-NUS Academic Medical Center, Singapore, Singapore.
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35
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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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36
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Kyle SM, Vashi N, Justice MJ. Rett syndrome: a neurological disorder with metabolic components. Open Biol 2018; 8:170216. [PMID: 29445033 PMCID: PMC5830535 DOI: 10.1098/rsob.170216] [Citation(s) in RCA: 101] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 01/18/2018] [Indexed: 02/06/2023] Open
Abstract
Rett syndrome (RTT) is a neurological disorder caused by mutations in the X-linked gene methyl-CpG-binding protein 2 (MECP2), a ubiquitously expressed transcriptional regulator. Despite remarkable scientific progress since its discovery, the mechanism by which MECP2 mutations cause RTT symptoms is largely unknown. Consequently, treatment options for patients are currently limited and centred on symptom relief. Thought to be an entirely neurological disorder, RTT research has focused on the role of MECP2 in the central nervous system. However, the variety of phenotypes identified in Mecp2 mutant mouse models and RTT patients implicate important roles for MeCP2 in peripheral systems. Here, we review the history of RTT, highlighting breakthroughs in the field that have led us to present day. We explore the current evidence supporting metabolic dysfunction as a component of RTT, presenting recent studies that have revealed perturbed lipid metabolism in the brain and peripheral tissues of mouse models and patients. Such findings may have an impact on the quality of life of RTT patients as both dietary and drug intervention can alter lipid metabolism. Ultimately, we conclude that a thorough knowledge of MeCP2's varied functional targets in the brain and body will be required to treat this complex syndrome.
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Affiliation(s)
- Stephanie M Kyle
- Genetics and Genome Biology Program, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, Ontario, Canada M5G 0A4
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Neeti Vashi
- Genetics and Genome Biology Program, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, Ontario, Canada M5G 0A4
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada M5S 1A1
| | - Monica J Justice
- Genetics and Genome Biology Program, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, Ontario, Canada M5G 0A4
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada M5S 1A1
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Progressive Changes in a Distributed Neural Circuit Underlie Breathing Abnormalities in Mice Lacking MeCP2. J Neurosci 2017; 36:5572-86. [PMID: 27194336 DOI: 10.1523/jneurosci.2330-15.2016] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 04/13/2016] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Rett syndrome (RTT) is a neurodevelopmental disorder caused by mutations in Methyl-CpG-binding protein 2 (MECP2). Severe breathing abnormalities are common in RTT and are reproduced in mouse models of RTT. Previously, we found that removing MeCP2 from the brainstem and spinal cord in mice caused early lethality and abnormal breathing. To determine whether loss of MeCP2 in functional components of the respiratory network causes specific breathing disorders, we used the Cre/LoxP system to differentially manipulate MeCP2 expression throughout the brainstem respiratory network, specifically within HoxA4-derived tissues, which include breathing control circuitry within the nucleus tractus solitarius and the caudal part of ventral respiratory column but do not include more rostral parts of the breathing control circuitry. To determine whether respiratory phenotypes manifested in animals with MeCP2 removed from specific pons medullary respiratory circuits, we performed whole-body plethysmography and electrophysiological recordings from in vitro brainstem slices from mice lacking MeCP2 in different circuits. Our results indicate that MeCP2 expression in the medullary respiratory network is sufficient for normal respiratory rhythm and preventing apnea. However, MeCP2 expression within components of the breathing circuitry rostral to the HoxA4 domain are neither sufficient to prevent the hyperventilation nor abnormal hypoxic ventilatory response. Surprisingly, we found that MeCP2 expression in the HoxA4 domain alone is critical for survival. Our study reveals that MeCP2 is differentially required in select respiratory components for different aspects of respiratory functions, and collectively for the integrity of this network functions to maintain proper respiration. SIGNIFICANCE STATEMENT Breathing abnormalities are a significant clinical feature in Rett syndrome and are robustly reproduced in the mouse models of this disease. Previous work has established that alterations in the function of MeCP2, the protein encoded by the gene mutated in Rett syndrome, within the hindbrain are critical for control of normal breathing. Here we show that MeCP2 function plays distinct roles in specific brainstem regions in the genesis of various aspects of abnormal breathing. This provides insight into the pathogenesis of these breathing abnormalities in Rett syndrome, which could be used to target treatments to improve these symptoms. Furthermore, it provides further knowledge about the fundamental neural circuits that control breathing.
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Gadalla KK, Vudhironarit T, Hector RD, Sinnett S, Bahey NG, Bailey ME, Gray SJ, Cobb SR. Development of a Novel AAV Gene Therapy Cassette with Improved Safety Features and Efficacy in a Mouse Model of Rett Syndrome. Mol Ther Methods Clin Dev 2017; 5:180-190. [PMID: 28497075 PMCID: PMC5423329 DOI: 10.1016/j.omtm.2017.04.007] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Accepted: 04/19/2017] [Indexed: 12/21/2022]
Abstract
Rett syndrome (RTT), caused by loss-of-function mutations in the MECP2 gene, is a neurological disorder characterized by severe impairment of motor and cognitive functions. The aim of this study was to investigate the impact of vector design, dosage, and delivery route on the efficacy and safety of gene augmentation therapy in mouse models of RTT. Our results show that AAV-mediated delivery of MECP2 to Mecp2 null mice by systemic administration, and utilizing a minimal endogenous promoter, was associated with a narrow therapeutic window and resulted in liver toxicity at higher doses. Lower doses of this vector significantly extended the survival of mice lacking MeCP2 or expressing a mutant T158M allele but had no impact on RTT-like neurological phenotypes. Modifying vector design by incorporating an extended Mecp2 promoter and additional regulatory 3' UTR elements significantly reduced hepatic toxicity after systemic administration. Moreover, direct cerebroventricular injection of this vector into neonatal Mecp2-null mice resulted in high brain transduction efficiency, increased survival and body weight, and an amelioration of RTT-like phenotypes. Our results show that controlling levels of MeCP2 expression in the liver is achievable through modification of the expression cassette. However, it also highlights the importance of achieving high brain transduction to impact the RTT-like phenotypes.
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Affiliation(s)
- Kamal K.E. Gadalla
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
- Pharmacology Department, Faculty of Medicine, Tanta University, Tanta 31527, Egypt
| | - Thishnapha Vudhironarit
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Ralph D. Hector
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Sarah Sinnett
- Gene Therapy Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Carolina Institute for Developmental Disabilities, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Noha G. Bahey
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
- Histology Department, Faculty of Medicine, Tanta University, Tanta 31527, Egypt
| | - Mark E.S. Bailey
- School of Life Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Steven J. Gray
- Gene Therapy Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Carolina Institute for Developmental Disabilities, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Department of Ophthalmology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA
| | - Stuart R. Cobb
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
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Lamonica JM, Kwon DY, Goffin D, Fenik P, Johnson BS, Cui Y, Guo H, Veasey S, Zhou Z. Elevating expression of MeCP2 T158M rescues DNA binding and Rett syndrome-like phenotypes. J Clin Invest 2017; 127:1889-1904. [PMID: 28394263 DOI: 10.1172/jci90967] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 02/09/2017] [Indexed: 12/27/2022] Open
Abstract
Mutations in the X-linked gene encoding methyl-CpG-binding protein 2 (MeCP2) cause Rett syndrome (RTT), a neurological disorder affecting cognitive development, respiration, and motor function. Genetic restoration of MeCP2 expression reverses RTT-like phenotypes in mice, highlighting the need to search for therapeutic approaches. Here, we have developed knockin mice recapitulating the most common RTT-associated missense mutation, MeCP2 T158M. We found that the T158M mutation impaired MECP2 binding to methylated DNA and destabilized MeCP2 protein in an age-dependent manner, leading to the development of RTT-like phenotypes in these mice. Genetic elevation of MeCP2 T158M expression ameliorated multiple RTT-like features, including motor dysfunction and breathing irregularities, in both male and female mice. These improvements were accompanied by increased binding of MeCP2 T158M to DNA. Further, we found that the ubiquitin/proteasome pathway was responsible for MeCP2 T158M degradation and that proteasome inhibition increased MeCP2 T158M levels. Together, these findings demonstrate that increasing MeCP2 T158M protein expression is sufficient to mitigate RTT-like phenotypes and support the targeting of MeCP2 T158M expression or stability as an alternative therapeutic approach.
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CREB Signaling Is Involved in Rett Syndrome Pathogenesis. J Neurosci 2017; 37:3671-3685. [PMID: 28270572 DOI: 10.1523/jneurosci.3735-16.2017] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 02/17/2017] [Accepted: 02/24/2017] [Indexed: 12/21/2022] Open
Abstract
Rett syndrome (RTT) is a debilitating neurodevelopmental disorder caused by mutations in the MECP2 gene. To facilitate the study of cellular mechanisms in human cells, we established several human stem cell lines: human embryonic stem cell (hESC) line carrying the common T158M mutation (MECP2T158M/T158M ), hESC line expressing no MECP2 (MECP2-KO), congenic pair of wild-type and mutant RTT patient-specific induced pluripotent stem cell (iPSC) line carrying the V247fs mutation (V247fs-WT and V247fs-MT), and iPSC line in which the V247fs mutation was corrected by CRISPR/Cas9-based genome editing (V247fs-MT-correction). Detailed analyses of forebrain neurons differentiated from these human stem cell lines revealed genotype-dependent quantitative phenotypes in neurite growth, dendritic complexity, and mitochondrial function. At the molecular level, we found a significant reduction in the level of CREB and phosphorylated CREB in forebrain neurons differentiated from MECP2T158M/T158M , MECP2-KO, and V247fs-MT stem cell lines. Importantly, overexpression of CREB or pharmacological activation of CREB signaling in those forebrain neurons rescued the phenotypes in neurite growth, dendritic complexity, and mitochondrial function. Finally, pharmacological activation of CREB in the female Mecp2 heterozygous mice rescued several behavioral defects. Together, our study establishes a robust in vitro platform for consistent quantitative evaluation of genotype-dependent RTT phenotypes, reveals a previously unappreciated role of CREB signaling in RTT pathogenesis, and identifies a potential therapeutic target for RTT.SIGNIFICANCE STATEMENT Our study establishes a robust human stem cell-based platform for consistent quantitative evaluation of genotype-dependent Rett syndrome (RTT) phenotypes at the cellular level. By providing the first evidence that enhancing cAMP response element binding protein signaling can alleviate RTT phenotypes both in vitro and in vivo, we reveal a previously unappreciated role of cAMP response element binding protein signaling in RTT pathogenesis, and identify a potential therapeutic target for RTT.
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Genetic and Pharmacological Reversibility of Phenotypes in Mouse Models of Autism Spectrum Disorder. ADVANCES IN ANATOMY, EMBRYOLOGY, AND CELL BIOLOGY 2017; 224:189-211. [PMID: 28551757 DOI: 10.1007/978-3-319-52498-6_10] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
As autism spectrum disorder (ASD) is largely regarded as a neurodevelopmental condition, long-time consensus was that its hallmark features are irreversible. However, several studies from recent years using defined mouse models of ASD have provided clear evidence that in mice neurobiological and behavioural alterations can be ameliorated or even reversed by genetic restoration or pharmacological treatment either before or after symptom onset. Here, we review findings on genetic and pharmacological reversibility of phenotypes in mouse models of ASD. Our review should give a comprehensive overview on both aspects and encourage future studies to better understand the underlying molecular mechanisms that might be translatable from animals to humans.
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Veeraragavan S, Wan YW, Connolly DR, Hamilton SM, Ward CS, Soriano S, Pitcher MR, McGraw CM, Huang SG, Green JR, Yuva LA, Liang AJ, Neul JL, Yasui DH, LaSalle JM, Liu Z, Paylor R, Samaco RC. Loss of MeCP2 in the rat models regression, impaired sociability and transcriptional deficits of Rett syndrome. Hum Mol Genet 2016; 25:3284-3302. [PMID: 27365498 PMCID: PMC5179927 DOI: 10.1093/hmg/ddw178] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Revised: 05/18/2016] [Accepted: 06/08/2016] [Indexed: 01/31/2023] Open
Abstract
Mouse models of the transcriptional modulator Methyl-CpG-Binding Protein 2 (MeCP2) have advanced our understanding of Rett syndrome (RTT). RTT is a 'prototypical' neurodevelopmental disorder with many clinical features overlapping with other intellectual and developmental disabilities (IDD). Therapeutic interventions for RTT may therefore have broader applications. However, the reliance on the laboratory mouse to identify viable therapies for the human condition may present challenges in translating findings from the bench to the clinic. In addition, the need to identify outcome measures in well-chosen animal models is critical for preclinical trials. Here, we report that a novel Mecp2 rat model displays high face validity for modelling psychomotor regression of a learned skill, a deficit that has not been shown in Mecp2 mice. Juvenile play, a behavioural feature that is uniquely present in rats and not mice, is also impaired in female Mecp2 rats. Finally, we demonstrate that evaluating the molecular consequences of the loss of MeCP2 in both mouse and rat may result in higher predictive validity with respect to transcriptional changes in the human RTT brain. These data underscore the similarities and differences caused by the loss of MeCP2 among divergent rodent species which may have important implications for the treatment of individuals with disease-causing MECP2 mutations. Taken together, these findings demonstrate that the Mecp2 rat model is a complementary tool with unique features for the study of RTT and highlight the potential benefit of cross-species analyses in identifying potential disease-relevant preclinical outcome measures.
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Affiliation(s)
- Surabi Veeraragavan
- Department of Molecular and Human Genetics
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Ying-Wooi Wan
- Department of Molecular and Human Genetics
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Daniel R Connolly
- Department of Molecular and Human Genetics
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | | | - Christopher S Ward
- Department of Pediatrics, Section of Neurology
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Sirena Soriano
- Department of Molecular and Human Genetics
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Meagan R Pitcher
- Program in Translational Biology and Molecular Medicine
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Christopher M McGraw
- Medical Scientist Training Program, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Sharon G Huang
- Department of Molecular and Human Genetics
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | | | - Lisa A Yuva
- Department of Molecular and Human Genetics
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Agnes J Liang
- Department of Molecular and Human Genetics
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Jeffrey L Neul
- Department of Pediatrics, Section of Neurology
- Program in Translational Biology and Molecular Medicine
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Dag H Yasui
- Rowe Program in Human Genetics, University of California Davis, Davis, CA, USA
| | - Janine M LaSalle
- Rowe Program in Human Genetics, University of California Davis, Davis, CA, USA
| | - Zhandong Liu
- Department of Pediatrics, Section of Neurology
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | | | - Rodney C Samaco
- Department of Molecular and Human Genetics
- Program in Translational Biology and Molecular Medicine
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
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Filosa S, Pecorelli A, D'Esposito M, Valacchi G, Hajek J. Exploring the possible link between MeCP2 and oxidative stress in Rett syndrome. Free Radic Biol Med 2015; 88:81-90. [PMID: 25960047 DOI: 10.1016/j.freeradbiomed.2015.04.019] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2015] [Revised: 04/10/2015] [Accepted: 04/13/2015] [Indexed: 01/27/2023]
Abstract
Rett syndrome (RTT, MIM 312750) is a rare and orphan progressive neurodevelopmental disorder affecting girls almost exclusively, with a frequency of 1/15,000 live births of girls. The disease is characterized by a period of 6 to 18 months of apparently normal neurodevelopment, followed by early neurological regression, with a progressive loss of acquired cognitive, social, and motor skills. RTT is known to be caused in 95% of the cases by sporadic de novo loss-of-function mutations in the X-linked methyl-CpG-binding protein 2 (MECP2) gene encoding methyl-CpG binding protein 2 (MeCP2), a nuclear protein able to regulate gene expression. Despite almost two decades of research into the functions and role of MeCP2, little is known about the mechanisms leading from MECP2 mutation to the disease. Oxidative stress (OS) is involved in the pathogenic mechanisms of several neurodevelopmental and neurodegenerative disorders, although in many cases it is not clear whether OS is a cause or a consequence of the pathology. Fairly recently, the presence of a systemic OS has been demonstrated in RTT patients with a strong correlation with the patients' clinical status. The link between MECP2 mutation and the redox imbalance found in RTT is not clear. Animal studies have suggested a possible direct correlation between Mecp2 mutation and increased OS levels. In addition, the restoration of Mecp2 function in astrocytes significantly improves the developmental outcome of Mecp2-null mice and reexpression of Mecp2 gene in the brain of null mice restored oxidative damage, suggesting that Mecp2 loss of function can be involved in oxidative brain damage. Starting from the evidence that oxidative damage in the brain of Mecp2-null mice precedes the onset of symptoms, we evaluated whether, based on the current literature, the dysfunctions described in RTT could be a consequence or, in contrast, could be caused by OS. We also analyzed whether therapies that at least partially treated some RTT symptoms can play a role in defense against OS. At this stage we can propose that OS could be one of the main causes of the dysfunctions observed in RTT. In addition, the major part of the therapies recommended to alleviate RTT symptoms have been shown to interfere with oxidative homeostasis, suggesting that MeCP2 could somehow be involved in the protection of the brain from OS.
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Affiliation(s)
- Stefania Filosa
- Institute of Biosciences and BioResources-CNR, UOS Naples, Italy; IRCCS Neuromed, Pozzilli, Italy
| | - Alessandra Pecorelli
- Child Neuropsychiatry Unit, University General Hospital, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Maurizio D'Esposito
- Institute of Genetics and Biophysics "A. Buzzati-Traverso"-CNR, Naples, Italy; IRCCS Neuromed, Pozzilli, Italy
| | - Giuseppe Valacchi
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy; Department of Food and Nutrition, Kyung Hee University, Seoul, South Korea.
| | - Joussef Hajek
- Child Neuropsychiatry Unit, University General Hospital, Azienda Ospedaliera Universitaria Senese, Siena, Italy
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Gadalla KKE, Ross PD, Hector RD, Bahey NG, Bailey MES, Cobb SR. Gene therapy for Rett syndrome: prospects and challenges. FUTURE NEUROLOGY 2015. [DOI: 10.2217/fnl.15.29] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Rett syndrome (RTT) is a neurological disorder that affects females and is caused by loss-of-function mutations in the X-linked gene MECP2. Deletion of Mecp2 in mice results in a constellation of neurological features that resemble those seen in RTT patients. Experiments in mice have demonstrated that restoration of MeCP2, even at adult stages, reverses several aspects of the RTT-like pathology suggesting that the disorder may be inherently treatable. This has provided an impetus to explore several therapeutic approaches targeting RTT at the level of the gene, including gene therapy, activation of MECP2 on the inactive X chromosome and read-through and repair of RTT-causing mutations. Here, we review these different strategies and the challenges of gene-based approaches in RTT.
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Affiliation(s)
- Kamal KE Gadalla
- University of Glasgow, Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, Glasgow, UK
- Pharmacology Department, Faculty of Medicine, Tanta University, Egypt
| | - Paul D Ross
- University of Glasgow, Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, Glasgow, UK
| | - Ralph D Hector
- University of Glasgow, Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, Glasgow, UK
| | - Noha G Bahey
- University of Glasgow, Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, Glasgow, UK
- Histology Department, Faculty of Medicine, Tanta University, Egypt
| | - Mark ES Bailey
- School of Life Sciences, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Stuart R Cobb
- University of Glasgow, Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, Glasgow, UK
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Baker SA, Lombardi LM, Zoghbi HY. Karyopherin α 3 and karyopherin α 4 proteins mediate the nuclear import of methyl-CpG binding protein 2. J Biol Chem 2015; 290:22485-93. [PMID: 26245896 DOI: 10.1074/jbc.m115.658104] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Indexed: 11/06/2022] Open
Abstract
Methyl-CpG binding protein 2 (MeCP2) is a nuclear protein with important roles in regulating chromatin structure and gene expression, and mutations in MECP2 cause Rett syndrome (RTT). Within the MeCP2 protein sequence, the nuclear localization signal (NLS) is reported to reside between amino acids 255-271, and certain RTT-causing mutations overlap with the MeCP2 NLS, suggesting that they may alter nuclear localization. One such mutation, R270X, is predicted to interfere with the localization of MeCP2, but recent in vivo studies have demonstrated that this mutant remains entirely nuclear. To clarify the mechanism of MeCP2 nuclear import, we isolated proteins that interact with the NLS and identified karyopherin α 3 (KPNA3 or Kap-α3) and karyopherin α 4 (KPNA4 or Kap-α4) as key binding partners of MeCP2. MeCP2-R270X did not interact with KPNA4, consistent with a requirement for an intact NLS in this interaction. However, this mutant retains binding to KPNA3, accounting for the normal localization of MeCP2-R270X to the nucleus. These data provide a mechanism for MeCP2 nuclear import and have implications for the design of therapeutics aimed at modulating the function of MeCP2 in RTT patients.
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Affiliation(s)
- Steven Andrew Baker
- From the Program in Developmental Biology, the Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, Texas 77030 Medical Scientist Training Program
| | - Laura Marie Lombardi
- the Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, Texas 77030 Department of Molecular and Human Genetics and Howard Hughes Medical Institute
| | - Huda Yahya Zoghbi
- From the Program in Developmental Biology, the Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, Texas 77030 Department of Molecular and Human Genetics and Howard Hughes Medical Institute, Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030 and
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Abstract
Rett syndrome (RTT) is a syndromic autism spectrum disorder caused by loss-of-function mutations in MECP2. The methyl CpG binding protein 2 binds methylcytosine and 5-hydroxymethycytosine at CpG sites in promoter regions of target genes, controlling their transcription by recruiting co-repressors and co-activators. Several preclinical studies in mouse models have identified rational molecular targets for drug therapies aimed at correcting the underlying neural dysfunction. These targeted therapies are increasingly translating into human clinical trials. In this review, we present an overview of RTT and describe the current state of preclinical studies in methyl CpG binding protein 2-based mouse models, as well as current clinical trials in individuals with RTT.
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Affiliation(s)
- Lucas Pozzo-Miller
- />Department of Neurobiology, Civitan International Research Center, The University of Alabama at Birmingham, Birmingham, AL USA
| | - Sandipan Pati
- />Department of Neurology, Epilepsy Division, Civitan International Research Center, The University of Alabama at Birmingham, Birmingham, AL USA
| | - Alan K. Percy
- />Department of Pediatrics, Civitan International Research Center, The University of Alabama at Birmingham, Birmingham, AL USA
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