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Schmitt I, Evert BO, Sharma A, Khazneh H, Murgatroyd C, Wüllner U. The Alpha-Synuclein Gene (SNCA) is a Genomic Target of Methyl-CpG Binding Protein 2 (MeCP2)-Implications for Parkinson's Disease and Rett Syndrome. Mol Neurobiol 2024:10.1007/s12035-024-03974-3. [PMID: 38429622 DOI: 10.1007/s12035-024-03974-3] [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: 10/06/2023] [Accepted: 01/18/2024] [Indexed: 03/03/2024]
Abstract
Mounting evidence suggests a prominent role for alpha-synuclein (a-syn) in neuronal cell function. Alterations in the levels of cellular a-syn have been hypothesized to play a critical role in the development of Parkinson's disease (PD); however, mechanisms that control expression of the gene for a-syn (SNCA) in cis and trans as well as turnover of a-syn are not well understood. We analyzed whether methyl-CpG binding protein 2 (MeCP2), a protein that specifically binds methylated DNA, thus regulating transcription, binds at predicted binding sites in intron 1 of the SNCA gene and regulates a-syn protein expression. Chromatin immunoprecipitation (ChIP) and electrophoretic mobility-shift assays (EMSA) were used to confirm binding of MeCP2 to regulatory regions of SNCA. Site-specific methylation and introduction of localized mutations by CRISPR/Cas9 were used to investigate the binding properties of MeCP2 in human SK-N-SH neuroblastoma cells. The significance of MeCP2 for SNCA regulation was further investigated by overexpressing MeCP2 and mutated variants of MeCP2 in MeCP2 knockout cells. We found that methylation-dependent binding of MeCP2 at a restricted region of intron 1 of SNCA had a significant impact on the production of a-syn. A single nucleotide substitution near to CpG1 strongly increased the binding of MeCP2 to intron 1 of SNCA and decreased a-syn protein expression by 60%. In contrast, deletion of a single nucleotide closed to CpG2 led to reduced binding of MeCP2 and significantly increased a-syn levels. In accordance, knockout of MeCP2 in SK-N-SH cells resulted in a significant increase in a-syn production, demonstrating that SNCA is a genomic target for MeCP2 regulation. In addition, the expression of two mutated MeCP2 variants found in Rett syndrome (RTT) showed a loss of their ability to reduce a-syn expression. This study demonstrates that methylation of CpGs and binding of MeCP2 to intron 1 of the SNCA gene plays an important role in the control of a-syn expression. In addition, the changes in SNCA regulation found by expression of MeCP2 variants carrying mutations found in RTT patients may be of importance for the elucidation of a new molecular pathway in RTT, a rare neurological disorder caused by mutations in MECP2.
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Affiliation(s)
- Ina Schmitt
- Department of Neurology, University of Bonn, Bonn, Germany
- German Centre for Neurodegenerative Disease (DZNE), Bonn, Germany
| | - Bernd O Evert
- Department of Neurology, University of Bonn, Bonn, Germany
| | - Amit Sharma
- Department of Neurosurgery, University of Bonn, Bonn, Germany
| | - Hassan Khazneh
- Department of Neurology, University of Bonn, Bonn, Germany
| | - Chris Murgatroyd
- Department of Life Sciences, Manchester Metropolitan University, Manchester, UK
| | - Ullrich Wüllner
- Department of Neurology, University of Bonn, Bonn, Germany.
- German Centre for Neurodegenerative Disease (DZNE), Bonn, Germany.
- Department of Neurodegenerative Diseases, University of Bonn, Bonn, Germany.
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Pascual-Alonso A, Xiol C, Smirnov D, Kopajtich R, Prokisch H, Armstrong J. Identification of molecular signatures and pathways involved in Rett syndrome using a multi-omics approach. Hum Genomics 2023; 17:85. [PMID: 37710353 PMCID: PMC10503149 DOI: 10.1186/s40246-023-00532-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 09/03/2023] [Indexed: 09/16/2023] Open
Abstract
BACKGROUND Rett syndrome (RTT) is a neurodevelopmental disorder mainly caused by mutations in the methyl-CpG-binding protein 2 gene (MECP2). MeCP2 is a multi-functional protein involved in many cellular processes, but the mechanisms by which its dysfunction causes disease are not fully understood. The duplication of the MECP2 gene causes a distinct disorder called MECP2 duplication syndrome (MDS), highlighting the importance of tightly regulating its dosage for proper cellular function. Additionally, some patients with mutations in genes other than MECP2 exhibit phenotypic similarities with RTT, indicating that these genes may also play a role in similar cellular functions. The purpose of this study was to characterise the molecular alterations in patients with RTT in order to identify potential biomarkers or therapeutic targets for this disorder. METHODS We used a combination of transcriptomics (RNAseq) and proteomics (TMT mass spectrometry) to characterise the expression patterns in fibroblast cell lines from 22 patients with RTT and detected mutation in MECP2, 15 patients with MDS, 12 patients with RTT-like phenotypes and 13 healthy controls. Transcriptomics and proteomics data were used to identify differentially expressed genes at both RNA and protein levels, which were further inspected via enrichment and upstream regulator analyses and compared to find shared features in patients with RTT. RESULTS We identified molecular alterations in cellular functions and pathways that may contribute to the disease phenotype in patients with RTT, such as deregulated cytoskeletal components, vesicular transport elements, ribosomal subunits and mRNA processing machinery. We also compared RTT expression profiles with those of MDS seeking changes in opposite directions that could lead to the identification of MeCP2 direct targets. Some of the deregulated transcripts and proteins were consistently affected in patients with RTT-like phenotypes, revealing potentially relevant molecular processes in patients with overlapping traits and different genetic aetiology. CONCLUSIONS The integration of data in a multi-omics analysis has helped to interpret the molecular consequences of MECP2 dysfunction, contributing to the characterisation of the molecular landscape in patients with RTT. The comparison with MDS provides knowledge of MeCP2 direct targets, whilst the correlation with RTT-like phenotypes highlights processes potentially contributing to the pathomechanism leading these disorders.
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Affiliation(s)
- Ainhoa Pascual-Alonso
- Fundació Per La Recerca Sant Joan de Déu, Esplugues de Llobregat, Spain
- Institut de Recerca Sant Joan de Déu, Esplugues de Llobregat, Spain
| | - Clara Xiol
- Fundació Per La Recerca Sant Joan de Déu, Esplugues de Llobregat, Spain
- Institut de Recerca Sant Joan de Déu, Esplugues de Llobregat, Spain
| | - Dmitrii Smirnov
- Institute of Human Genetics, Technical University of Munich, Munich, Germany
- Institute of Neurogenomics, Helmholtz Zentrum München, Munich, Germany
| | - Robert Kopajtich
- Institute of Human Genetics, Technical University of Munich, Munich, Germany
- Institute of Neurogenomics, Helmholtz Zentrum München, Munich, Germany
| | - Holger Prokisch
- Institute of Human Genetics, Technical University of Munich, Munich, Germany
- Institute of Neurogenomics, Helmholtz Zentrum München, Munich, Germany
| | - Judith Armstrong
- Institut de Recerca Sant Joan de Déu, Esplugues de Llobregat, Spain.
- CIBER-ER (Biomedical Network Research Center for Rare Diseases), Instituto de Salud Carlos III (ISCIII), Madrid, Spain.
- Genomic Unit, Molecular and Genetic Medicine Section, Hospital Sant Joan de Déu, Barcelona, Spain.
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Petazzi P, Jorge-Torres OC, Gomez A, Scognamiglio I, Serra-Musach J, Merkel A, Grases D, Xiol C, O’Callaghan M, Armstrong J, Esteller M, Guil S. Global Impairment of Immediate-Early Genes Expression in Rett Syndrome Models and Patients Linked to Myelination Defects. Int J Mol Sci 2023; 24:ijms24021453. [PMID: 36674969 PMCID: PMC9864472 DOI: 10.3390/ijms24021453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Revised: 12/14/2022] [Accepted: 12/29/2022] [Indexed: 01/15/2023] Open
Abstract
Rett syndrome (RTT) is a severe neurodevelopmental disease caused almost exclusively by mutations to the MeCP2 gene. This disease may be regarded as a synaptopathy, with impairments affecting synaptic plasticity, inhibitory and excitatory transmission and network excitability. The complete understanding of the mechanisms behind how the transcription factor MeCP2 so profoundly affects the mammalian brain are yet to be determined. What is known, is that MeCP2 involvement in activity-dependent expression programs is a critical link between this protein and proper neuronal activity, which allows the correct maturation of connections in the brain. By using RNA-sequencing analysis, we found several immediate-early genes (IEGs, key mediators of activity-dependent responses) directly bound by MeCP2 at the chromatin level and upregulated in the hippocampus and prefrontal cortex of the Mecp2-KO mouse. Quantification of the IEGs response to stimulus both in vivo and in vitro detected an aberrant expression pattern in MeCP2-deficient neurons. Furthermore, altered IEGs levels were found in RTT patient's peripheral blood and brain regions of post-mortem samples, correlating with impaired expression of downstream myelination-related genes. Altogether, these data indicate that proper IEGs expression is crucial for correct synaptic development and that MeCP2 has a key role in the regulation of IEGs.
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Affiliation(s)
- Paolo Petazzi
- Josep Carreras Leukemia Research Institute, School of Medicine, University of Barcelona, Carrer Casanova 143, 400° floor, 08036 Barcelona, Spain
- RICORS-TERAV, Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Olga Caridad Jorge-Torres
- Josep Carreras Leukaemia Research Institute (IJC), Badalona, 08916 Barcelona, Spain
- Correspondence: (O.C.J.-T.); (S.G.); Tel.: +34-935572828 (O.C.J.-T. & S.G.)
| | - Antonio Gomez
- Biosciences Department, Faculty of Sciences and Technology (FCT), University of Vic-Central University of Catalonia (UVic-UCC), C. de la Laura, 13, 08500 Vic, Spain
| | - Iolanda Scognamiglio
- Cancer Epigenetics and Biology Program (PEBC), Bellvitge Biomedical Research Institute (IDIBELL), L’Hospitalet de Llobregat, 08908 Barcelona, Spain
| | - Jordi Serra-Musach
- Cancer Epigenetics and Biology Program (PEBC), Bellvitge Biomedical Research Institute (IDIBELL), L’Hospitalet de Llobregat, 08908 Barcelona, Spain
| | - Angelika Merkel
- Josep Carreras Leukaemia Research Institute (IJC), Badalona, 08916 Barcelona, Spain
| | - Daniela Grases
- Josep Carreras Leukaemia Research Institute (IJC), Badalona, 08916 Barcelona, Spain
| | - Clara Xiol
- Fundación San Juan de Dios, 08950 Barcelona, Spain
- Servei de Medicina Genètica i Molecular, Institut de Recerca Pediàtrica, Hospital Sant Joan de Déu, 08950 Barcelona, Spain
| | - Mar O’Callaghan
- Clínica Rett, Neurology Department, Hospital Sant Joan de Déu, 08950 Barcelona, Spain
- CIBER-ER (Biomedical Network Research Center for Rare Diseases), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Judith Armstrong
- Servei de Medicina Genètica i Molecular, Institut de Recerca Pediàtrica, Hospital Sant Joan de Déu, 08950 Barcelona, Spain
- CIBER-ER (Biomedical Network Research Center for Rare Diseases), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Manel Esteller
- Josep Carreras Leukaemia Research Institute (IJC), Badalona, 08916 Barcelona, Spain
- Centro de Investigacion Biomedica en Red Cancer (CIBERONC), 28029 Madrid, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona, Spain
- Physiological Sciences Department, School of Medicine and Health Sciences, University of Barcelona (UB), 08907 Barcelona, Spain
| | - Sonia Guil
- Josep Carreras Leukaemia Research Institute (IJC), Badalona, 08916 Barcelona, Spain
- Germans Trias i Pujol Health Science Research Institute, Badalona, 08916 Barcelona, Spain
- Correspondence: (O.C.J.-T.); (S.G.); Tel.: +34-935572828 (O.C.J.-T. & S.G.)
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5-HT 1A Receptor Agonist Treatment Partially Ameliorates Rett Syndrome Phenotypes in mecp2-Null Mice by Rescuing Impairment of Neuron Transmission and the CREB/BDNF Signaling Pathway. Int J Mol Sci 2022; 23:ijms232214025. [PMID: 36430502 PMCID: PMC9697184 DOI: 10.3390/ijms232214025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 11/10/2022] [Accepted: 11/11/2022] [Indexed: 11/16/2022] Open
Abstract
Rett syndrome (RTT) is an X-linked neurodevelopmental disorder caused by mutations in the gene that encodes methyl CpG-binding protein 2 (MECP2) and is characterized by the loss of acquired motor and language skills, stereotypic movements, respiratory abnormalities and autistic features. There has been no effective treatment for this disorder until now. In this study, we used a Mecp2-null (KO) mouse model of RTT to investigate whether repeated intraperitoneal treatment with the 5-HT1A receptor agonist tandospirone could improve the RTT phenotype. The results showed that administration of tandospirone significantly extended the lifespan of Mecp2-KO mice and obviously ameliorated RTT phenotypes, including general condition, hindlimb clasping, gait, tremor and breathing in Mecp2-KO mice. Tandospirone treatment significantly improved the impairment in GABAergic, glutaminergic, dopaminergic and serotoninergic neurotransmission in the brainstem of Mecp2-KO mice. Decreased dopaminergic neurotransmission in the cerebellum of Mecp2-KO mice was also significantly increased by tandospirone treatment. Moreover, RNA-sequencing analysis found that tandospirone modulates the RTT phenotype, partially through the CREB1/BDNF signaling pathway in Mecp2-KO mice. These findings provide a new option for clinical treatment.
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Bisgaard AM, Wong K, Højfeldt AK, Larsen JL, Schönewolf-Greulich B, Rønde G, Downs J, Stahlhut M. Decline in gross motor skills in adult Rett syndrome; results from a Danish longitudinal study. Am J Med Genet A 2021; 185:3683-3693. [PMID: 34296518 DOI: 10.1002/ajmg.a.62429] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 05/19/2021] [Accepted: 07/02/2021] [Indexed: 12/22/2022]
Abstract
Longevity of individuals with neurodevelopmental diseases as Rett syndrome (RTT) has increased and many reach adulthood and old age. There is therefore a need to increase knowledge about the course of RTT in adults in order to improve medical care management and quality of life. We did a longitudinal study to address if a possible decline in motor skills in adults with RTT can be explained by the presence of common medical conditions as epilepsy, breathing disturbance, and scoliosis. Data from the Danish RTT database, medical files, and videos from visits at the national Center for Rett syndrome were reviewed. The study included 24 individuals aged 30-66 years at last visit after a follow-up period of 6-12 years. Results showed a clinically observable and significant decline in gross motor skills using the Rett syndrome Gross Motor Scale (RSGMS) with a tendency of less decline in the individuals with the best motor abilities. The frequencies of comorbidities were high. Decline in RSGMS score was associated with the presence of epilepsy and severe scoliosis that had been conservatively managed. The results emphasize that epilepsy plays a significant role in the adult RTT life and management of severe scoliosis in the younger years has impact on the motor abilities in adulthood.
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Affiliation(s)
- Anne-Marie Bisgaard
- Department of Paediatrics and Adolescent Medicine, Center for Rett syndrome, Rigshospitalet, Copenhagen, Denmark
| | - Kingsley Wong
- Telethon Kids Institute, The University of Western Australia, Perth, Western Australia, Australia
| | - Anne-Katrine Højfeldt
- Department of Paediatrics and Adolescent Medicine, Center for Rett syndrome, Rigshospitalet, Copenhagen, Denmark
| | - Jane Lunding Larsen
- Department of Paediatrics and Adolescent Medicine, Center for Rett syndrome, Rigshospitalet, Copenhagen, Denmark
| | | | - Gitte Rønde
- Department of Paediatrics and Adolescent Medicine, Herlev Hospital, Copenhagen, Denmark
| | - Jenny Downs
- Telethon Kids Institute, The University of Western Australia, Perth, Western Australia, Australia
- Curtin School of Allied Health, Curtin University, Perth, Western Australia, Australia
| | - Michelle Stahlhut
- Department of Paediatrics and Adolescent Medicine, Center for Rett syndrome, Rigshospitalet, Copenhagen, Denmark
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6
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Kosillo P, Bateup HS. Dopaminergic Dysregulation in Syndromic Autism Spectrum Disorders: Insights From Genetic Mouse Models. Front Neural Circuits 2021; 15:700968. [PMID: 34366796 PMCID: PMC8343025 DOI: 10.3389/fncir.2021.700968] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 06/21/2021] [Indexed: 12/12/2022] Open
Abstract
Autism spectrum disorder (ASD) is a neurodevelopmental disorder defined by altered social interaction and communication, and repetitive, restricted, inflexible behaviors. Approximately 1.5-2% of the general population meet the diagnostic criteria for ASD and several brain regions including the cortex, amygdala, cerebellum and basal ganglia have been implicated in ASD pathophysiology. The midbrain dopamine system is an important modulator of cellular and synaptic function in multiple ASD-implicated brain regions via anatomically and functionally distinct dopaminergic projections. The dopamine hypothesis of ASD postulates that dysregulation of dopaminergic projection pathways could contribute to the behavioral manifestations of ASD, including altered reward value of social stimuli, changes in sensorimotor processing, and motor stereotypies. In this review, we examine the support for the idea that cell-autonomous changes in dopaminergic function are a core component of ASD pathophysiology. We discuss the human literature supporting the involvement of altered dopamine signaling in ASD including genetic, brain imaging and pharmacologic studies. We then focus on genetic mouse models of syndromic neurodevelopmental disorders in which single gene mutations lead to increased risk for ASD. We highlight studies that have directly examined dopamine neuron number, morphology, physiology, or output in these models. Overall, we find considerable support for the idea that the dopamine system may be dysregulated in syndromic ASDs; however, there does not appear to be a consistent signature and some models show increased dopaminergic function, while others have deficient dopamine signaling. We conclude that dopamine dysregulation is common in syndromic forms of ASD but that the specific changes may be unique to each genetic disorder and may not account for the full spectrum of ASD-related manifestations.
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Affiliation(s)
- Polina Kosillo
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, United States
| | - Helen S. Bateup
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, United States
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, United States
- Chan Zuckerberg Biohub, San Francisco, CA, United States
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Vashi N, Ackerley C, Post M, Justice MJ. Aberrant lung lipids cause respiratory impairment in a Mecp2-deficient mouse model of Rett syndrome. Hum Mol Genet 2021; 30:2161-2176. [PMID: 34230964 PMCID: PMC8561422 DOI: 10.1093/hmg/ddab182] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 05/11/2021] [Accepted: 06/28/2021] [Indexed: 11/14/2022] Open
Abstract
Severe respiratory impairment is a prominent feature of Rett syndrome (RTT), an X-linked disorder caused by mutations in methyl CpG-binding protein 2 (MECP2). Despite MECP2's ubiquitous expression, respiratory anomalies are attributed to neuronal dysfunction. Here, we show that neutral lipids accumulate in mouse Mecp2-mutant lungs, while surfactant phospholipids decrease. Conditional deletion of Mecp2 from lipid-producing alveolar epithelial 2 (AE2) cells causes aberrant lung lipids and respiratory symptoms, while deletion of Mecp2 from hindbrain neurons results in distinct respiratory abnormalities. Single-cell RNA sequencing of AE2 cells suggests lipid production and storage increase at the expense of phospholipid synthesis. Lipid production enzymes are confirmed as direct targets of MECP2-directed nuclear receptor corepressor 1/2 (NCOR1/2) transcriptional repression. Remarkably, lipid-lowering fluvastatin improves respiratory anomalies in Mecp2-mutant mice. These data implicate autonomous pulmonary loss of MECP2 in respiratory symptoms for the first time and have immediate impacts on patient care.
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Affiliation(s)
- Neeti Vashi
- Department of Molecular Genetics, University of Toronto, Toronto, ON, M5S 1A1, Canada.,Genetics and Genome Biology Program, Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, Toronto, ON, M5G 0A4, Canada
| | - Cameron Ackerley
- Translational Medicine Program, Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, Toronto, ON, M5G 0A4, Canada
| | - Martin Post
- Translational Medicine Program, Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, Toronto, ON, M5G 0A4, Canada
| | - Monica J Justice
- Department of Molecular Genetics, University of Toronto, Toronto, ON, M5S 1A1, Canada.,Genetics and Genome Biology Program, Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, Toronto, ON, M5G 0A4, Canada
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8
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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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Sandweiss AJ, Brandt VL, Zoghbi HY. Advances in understanding of Rett syndrome and MECP2 duplication syndrome: prospects for future therapies. Lancet Neurol 2020; 19:689-698. [PMID: 32702338 DOI: 10.1016/s1474-4422(20)30217-9] [Citation(s) in RCA: 90] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2019] [Revised: 05/07/2020] [Accepted: 05/12/2020] [Indexed: 01/07/2023]
Abstract
The X-linked gene encoding MECP2 is involved in two severe and complex neurodevelopmental disorders. Loss of function of the MeCP2 protein underlies Rett syndrome, whereas duplications of the MECP2 locus cause MECP2 duplication syndrome. Research on the mechanisms by which MeCP2 exerts effects on gene expression in neurons, studies of animal models bearing different disease-causing mutations, and more in-depth observations of clinical presentations have clarified some issues even as they have raised further questions. Yet there is enough evidence so far to suggest possible approaches to therapy for these two diseases that could go beyond attempting to address specific signs and symptoms (of which there are many) and instead target the pathophysiology underlying MECP2 disorders. Further work could bring antisense oligonucleotides, deep brain stimulation, and gene therapy into the clinic within the next decade or so.
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Affiliation(s)
- Alexander J Sandweiss
- Department of Pediatrics, Section of Neurology and Developmental Neurosciences, Baylor College of Medicine, Houston, TX, USA; Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX, USA
| | - Vicky L Brandt
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX, USA
| | - Huda Y Zoghbi
- Department of Pediatrics, Section of Neurology and Developmental Neurosciences, Baylor College of Medicine, Houston, TX, USA; Howard Hughes Medical Institute, and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA; Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX, USA.
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10
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Neul JL, Skinner SA, Annese F, Lane J, Heydemann P, Jones M, Kaufmann WE, Glaze DG, Percy AK. Metabolic Signatures Differentiate Rett Syndrome From Unaffected Siblings. Front Integr Neurosci 2020; 14:7. [PMID: 32161522 PMCID: PMC7052375 DOI: 10.3389/fnint.2020.00007] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2019] [Accepted: 01/30/2020] [Indexed: 01/07/2023] Open
Abstract
Rett syndrome (RTT, OMIM 312750), a severe neurodevelopmental disorder characterized by regression with loss of spoken language and hand skills, development of characteristic hand stereotypies, and gait dysfunction, is primarily caused by de novo mutations in the X-linked gene Methyl-CpG-binding protein 2 (MECP2). Currently, treatment options are limited to symptomatic management, however, reversal of disease phenotype is possible in mouse models by restoration of normal MECP2 gene expression. A significant challenge is the lack of biomarkers of disease state, disease severity, or treatment response. Using a non-targeted metabolomic approach we evaluated metabolite profiles in plasma from thirty-four people with RTT compared to thirty-seven unaffected age- and gender-matched siblings. We identified sixty-six significantly altered metabolites that cluster broadly into amino acid, nitrogen handling, and exogenous substance pathways. RTT disease metabolite and metabolic pathways abnormalities point to evidence of oxidative stress, mitochondrial dysfunction, and alterations in gut microflora. These observed changes provide insight into underlying pathological mechanisms and the foundation for biomarker discovery of disease severity biomarkers.
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Affiliation(s)
- Jeffrey L Neul
- Vanderbilt University Medical Center, Nashville, TN, United States.,Department of Neurosciences, University of California, San Diego, San Diego, CA, United States.,Baylor College of Medicine, Houston, TX, United States
| | | | - Fran Annese
- Greenwood Genetic Center, Greenwood, SC, United States
| | - Jane Lane
- Department of Pediatrics, University of Alabama at Birmingham, Birmingham, AL, United States
| | | | - Mary Jones
- Benioff Children's Hospital Oakland, University of California, San Francisco, San Francisco, CA, United States
| | | | | | - Alan K Percy
- Department of Pediatrics, University of Alabama at Birmingham, Birmingham, AL, United States
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Jorge-Torres OC, Szczesna K, Roa L, Casal C, Gonzalez-Somermeyer L, Soler M, Velasco CD, Martínez-San Segundo P, Petazzi P, Sáez MA, Delgado-Morales R, Fourcade S, Pujol A, Huertas D, Llobet A, Guil S, Esteller M. Inhibition of Gsk3b Reduces Nfkb1 Signaling and Rescues Synaptic Activity to Improve the Rett Syndrome Phenotype in Mecp2-Knockout Mice. Cell Rep 2019; 23:1665-1677. [PMID: 29742424 DOI: 10.1016/j.celrep.2018.04.010] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2017] [Revised: 02/07/2018] [Accepted: 03/31/2018] [Indexed: 12/01/2022] Open
Abstract
Rett syndrome (RTT) is the second leading cause of mental impairment in girls and is currently untreatable. RTT is caused, in more than 95% of cases, by loss-of-function mutations in the methyl CpG-binding protein 2 gene (MeCP2). We propose here a molecular target involved in RTT: the glycogen synthase kinase-3b (Gsk3b) pathway. Gsk3b activity is deregulated in Mecp2-knockout (KO) mice models, and SB216763, a specific inhibitor, is able to alleviate the clinical symptoms with consequences at the molecular and cellular levels. In vivo, inhibition of Gsk3b prolongs the lifespan of Mecp2-KO mice and reduces motor deficits. At the molecular level, SB216763 rescues dendritic networks and spine density, while inducing changes in the properties of excitatory synapses. Gsk3b inhibition can also decrease the nuclear activity of the Nfkb1 pathway and neuroinflammation. Altogether, our findings indicate that Mecp2 deficiency in the RTT mouse model is partially rescued following treatment with SB216763.
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Affiliation(s)
- Olga C Jorge-Torres
- Cancer Epigenetics and Biology Program (PEBC), Bellvitge Biomedical Research Institute (IDIBELL), 08908 L'Hospitalet, Barcelona, Catalonia, Spain
| | - Karolina Szczesna
- Cancer Epigenetics and Biology Program (PEBC), Bellvitge Biomedical Research Institute (IDIBELL), 08908 L'Hospitalet, Barcelona, Catalonia, Spain
| | - Laura Roa
- Cancer Epigenetics and Biology Program (PEBC), Bellvitge Biomedical Research Institute (IDIBELL), 08908 L'Hospitalet, Barcelona, Catalonia, Spain
| | - Carme Casal
- Cancer Epigenetics and Biology Program (PEBC), Bellvitge Biomedical Research Institute (IDIBELL), 08908 L'Hospitalet, Barcelona, Catalonia, Spain
| | - Louisa Gonzalez-Somermeyer
- Cancer Epigenetics and Biology Program (PEBC), Bellvitge Biomedical Research Institute (IDIBELL), 08908 L'Hospitalet, Barcelona, Catalonia, Spain
| | - Marta Soler
- Cancer Epigenetics and Biology Program (PEBC), Bellvitge Biomedical Research Institute (IDIBELL), 08908 L'Hospitalet, Barcelona, Catalonia, Spain
| | - Cecilia D Velasco
- Laboratory of Neurobiology, Bellvitge Biomedical Research Institute (IDIBELL), 08907 L'Hospitalet de Llobregat, Barcelona, Catalonia, Spain; Department of Pathology and Experimental Therapeutics, Faculty of Medicine, 08907 L'Hospitalet de Llobregat, Barcelona, Catalonia, Spain; Institute of Neurosciences, University of Barcelona, 08907 L'Hospitalet de Llobregat, Barcelona, Catalonia, Spain
| | - Pablo Martínez-San Segundo
- Laboratory of Neurobiology, Bellvitge Biomedical Research Institute (IDIBELL), 08907 L'Hospitalet de Llobregat, Barcelona, Catalonia, Spain; Department of Pathology and Experimental Therapeutics, Faculty of Medicine, 08907 L'Hospitalet de Llobregat, Barcelona, Catalonia, Spain; Institute of Neurosciences, University of Barcelona, 08907 L'Hospitalet de Llobregat, Barcelona, Catalonia, Spain
| | - Paolo Petazzi
- Cancer Epigenetics and Biology Program (PEBC), Bellvitge Biomedical Research Institute (IDIBELL), 08908 L'Hospitalet, Barcelona, Catalonia, Spain
| | - Mauricio A Sáez
- Cancer Epigenetics and Biology Program (PEBC), Bellvitge Biomedical Research Institute (IDIBELL), 08908 L'Hospitalet, Barcelona, Catalonia, Spain
| | - Raúl Delgado-Morales
- Cancer Epigenetics and Biology Program (PEBC), Bellvitge Biomedical Research Institute (IDIBELL), 08908 L'Hospitalet, Barcelona, Catalonia, Spain; Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience (MHeNs), Maastricht University, Maastricht, the Netherlands
| | - Stephane Fourcade
- Neurometabolic Diseases Laboratory, Bellvitge Biomedical Research Institute (IDIBELL), 08908 L'Hospitalet, Barcelona, Catalonia, Spain; Institute of Neuropathology, University of Barcelona, Barcelona, Catalonia, Spain; Center for Biomedical Research on Rare Diseases (CIBERER), ISCIII, Madrid, Spain
| | - Aurora Pujol
- Neurometabolic Diseases Laboratory, Bellvitge Biomedical Research Institute (IDIBELL), 08908 L'Hospitalet, Barcelona, Catalonia, Spain; Institute of Neuropathology, University of Barcelona, Barcelona, Catalonia, Spain; Center for Biomedical Research on Rare Diseases (CIBERER), ISCIII, Madrid, Spain; Institucio Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Catalonia, Spain
| | - Dori Huertas
- Cancer Epigenetics and Biology Program (PEBC), Bellvitge Biomedical Research Institute (IDIBELL), 08908 L'Hospitalet, Barcelona, Catalonia, Spain
| | - Artur Llobet
- Laboratory of Neurobiology, Bellvitge Biomedical Research Institute (IDIBELL), 08907 L'Hospitalet de Llobregat, Barcelona, Catalonia, Spain; Department of Pathology and Experimental Therapeutics, Faculty of Medicine, 08907 L'Hospitalet de Llobregat, Barcelona, Catalonia, Spain; Institute of Neurosciences, University of Barcelona, 08907 L'Hospitalet de Llobregat, Barcelona, Catalonia, Spain
| | - Sonia Guil
- Cancer Epigenetics and Biology Program (PEBC), Bellvitge Biomedical Research Institute (IDIBELL), 08908 L'Hospitalet, Barcelona, Catalonia, Spain.
| | - Manel Esteller
- Cancer Epigenetics and Biology Program (PEBC), Bellvitge Biomedical Research Institute (IDIBELL), 08908 L'Hospitalet, Barcelona, Catalonia, Spain; Institucio Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Catalonia, Spain; Physiological Sciences Department, School of Medicine and Health Sciences, University of Barcelona (UB), 08907 Catalonia, Spain.
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Smith ES, Smith DR, Eyring C, Braileanu M, Smith-Connor KS, Ei Tan Y, Fowler AY, Hoffman GE, Johnston MV, Kannan S, Blue ME. Altered trajectories of neurodevelopment and behavior in mouse models of Rett syndrome. Neurobiol Learn Mem 2019; 165:106962. [PMID: 30502397 PMCID: PMC8040058 DOI: 10.1016/j.nlm.2018.11.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 10/17/2018] [Accepted: 11/16/2018] [Indexed: 12/12/2022]
Abstract
Rett Syndrome (RTT) is a genetic disorder that is caused by mutations in the x-linked gene coding for methyl-CpG-biding-protein 2 (MECP2) and that mainly affects females. Male and female transgenic mouse models of RTT have been studied extensively, and we have learned a great deal regarding RTT neuropathology and how MeCP2 deficiency may be influencing brain function and maturation. In this manuscript we review what is known concerning structural and coinciding functional and behavioral deficits in RTT and in mouse models of MeCP2 deficiency. We also introduce our own corroborating data regarding behavioral phenotype and morphological alterations in volume of the cortex and striatum and the density of neurons, aberrations in experience-dependent plasticity within the barrel cortex and the impact of MeCP2 loss on glial structure. We conclude that regional structural changes in genetic models of RTT show great similarity to the alterations in brain structure of patients with RTT. These region-specific modifications often coincide with phenotype onset and contribute to larger issues of circuit connectivity, progression, and severity. Although the alterations seen in mouse models of RTT appear to be primarily due to cell-autonomous effects, there are also non-cell autonomous mechanisms including those caused by MeCP2-deficient glia that negatively impact healthy neuronal function. Collectively, this body of work has provided a solid foundation on which to continue to build our understanding of the role of MeCP2 on neuronal and glial structure and function, its greater impact on neural development, and potential new therapeutic avenues.
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Affiliation(s)
- Elizabeth S Smith
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Dani R Smith
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Charlotte Eyring
- The Hugo W. Moser Research Institute at Kennedy Krieger, Inc., Baltimore, MD 21205, USA
| | - Maria Braileanu
- Undergraduate Program in Neuroscience, The Krieger School of Arts and Sciences, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Karen S Smith-Connor
- The Hugo W. Moser Research Institute at Kennedy Krieger, Inc., Baltimore, MD 21205, USA
| | - Yew Ei Tan
- Perdana University Graduate School of Medicine, Kuala Lumpur, Malaysia
| | - Amanda Y Fowler
- Department of Biology, Morgan State University, Baltimore, MD 21251, USA
| | - Gloria E Hoffman
- Department of Biology, Morgan State University, Baltimore, MD 21251, USA
| | - Michael V Johnston
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; The Hugo W. Moser Research Institute at Kennedy Krieger, Inc., Baltimore, MD 21205, USA
| | - Sujatha Kannan
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; The Hugo W. Moser Research Institute at Kennedy Krieger, Inc., Baltimore, MD 21205, USA
| | - Mary E Blue
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; The Hugo W. Moser Research Institute at Kennedy Krieger, Inc., Baltimore, MD 21205, USA.
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Zamberletti E, Gabaglio M, Piscitelli F, Brodie JS, Woolley-Roberts M, Barbiero I, Tramarin M, Binelli G, Landsberger N, Kilstrup-Nielsen C, Rubino T, Di Marzo V, Parolaro D. Cannabidivarin completely rescues cognitive deficits and delays neurological and motor defects in male Mecp2 mutant mice. J Psychopharmacol 2019; 33:894-907. [PMID: 31084246 DOI: 10.1177/0269881119844184] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
BACKGROUND Recent evidence suggests that 2-week treatment with the non-psychotomimetic cannabinoid cannabidivarin (CBDV) could be beneficial towards neurological and social deficits in early symptomatic Mecp2 mutant mice, a model of Rett syndrome (RTT). AIM The aim of this study was to provide further insights into the efficacy of CBDV in Mecp2-null mice using a lifelong treatment schedule (from 4 to 9 weeks of age) to evaluate its effect on recognition memory and neurological defects in both early and advanced stages of the phenotype progression. METHODS CBDV 0.2, 2, 20 and 200 mg/kg/day was administered to Mecp2-null mice from 4 to 9 weeks of age. Cognitive and neurological defects were monitored during the whole treatment schedule. Biochemical analyses were carried out in brain lysates from 9-week-old wild-type and knockout mice to evaluate brain-derived neurotrophic factor (BDNF) and insulin-like growth factor-1 (IGF-1) levels as well as components of the endocannabinoid system. RESULTS CBDV rescues recognition memory deficits in Mecp2 mutant mice and delays the appearance of neurological defects. At the biochemical level, it normalizes BDNF/IGF1 levels and the defective PI3K/AKT/mTOR pathway in Mecp2 mutant mice at an advanced stage of the disease. Mecp2 deletion upregulates CB1 and CB2 receptor levels in the brain and these changes are restored after CBDV treatment. CONCLUSIONS CBDV administration exerts an enduring rescue of memory deficits in Mecp2 mutant mice, an effect that is associated with the normalization of BDNF, IGF-1 and rpS6 phosphorylation levels as well as CB1 and CB2 receptor expression. CBDV delays neurological defects but this effect is only transient.
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Affiliation(s)
- Erica Zamberletti
- 1 Department of Biotechnology and Life Sciences (DBSV), University of Insubria, Varese, Italy
| | - Marina Gabaglio
- 1 Department of Biotechnology and Life Sciences (DBSV), University of Insubria, Varese, Italy
| | - Fabiana Piscitelli
- 2 Institute of Biomolecular Chemistry, Consiglio Nazionale delle Ricerche, Pozzuoli, Naples, Italy
| | | | | | - Isabella Barbiero
- 1 Department of Biotechnology and Life Sciences (DBSV), University of Insubria, Varese, Italy
| | - Marco Tramarin
- 1 Department of Biotechnology and Life Sciences (DBSV), University of Insubria, Varese, Italy
| | - Giorgio Binelli
- 1 Department of Biotechnology and Life Sciences (DBSV), University of Insubria, Varese, Italy
| | - Nicoletta Landsberger
- 4 Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy
| | | | - Tiziana Rubino
- 1 Department of Biotechnology and Life Sciences (DBSV), University of Insubria, Varese, Italy
| | - Vincenzo Di Marzo
- 2 Institute of Biomolecular Chemistry, Consiglio Nazionale delle Ricerche, Pozzuoli, Naples, Italy
| | - Daniela Parolaro
- 1 Department of Biotechnology and Life Sciences (DBSV), University of Insubria, Varese, Italy.,5 Zardi Gori Foundation, Milan, Italy
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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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Valacchi G, Pecorelli A, Cervellati C, Hayek J. 4-hydroxynonenal protein adducts: Key mediator in Rett syndrome oxinflammation. Free Radic Biol Med 2017; 111:270-280. [PMID: 28063942 DOI: 10.1016/j.freeradbiomed.2016.12.045] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 12/24/2016] [Accepted: 12/30/2016] [Indexed: 12/13/2022]
Abstract
In the last 15 years a strong correlation between oxidative stress (OxS) and Rett syndrome (RTT), a rare neurodevelopmental disorder known to be caused in 95% of the cases, by a mutation in the methyl-CpG-binding protein 2 (MECP2) gene, has been well documented. Here, we revised, summarized and discussed the current knowledge on the role of lipid peroxidation byproducts, with special emphasis on 4-hydroxynonenal (4HNE), in RTT pathophysiology. The posttranslational modifications of proteins via 4HNE, known as 4HNE protein adducts (4NHE-PAs), causing detrimental effects on protein functions, appear to contribute to the clinical severity of the syndrome, since their levels increase significantly during the subsequent 4 clinical stages, reaching the maximum degree at stage 4, represented by a late motor deterioration. In addition, 4HNE-PA are only partially removed due to the compromised functionality of the proteasome activity, contributing therefore to the cellular damage in RTT. All this will lead to a characteristic subclinical inflammation, defined "OxInflammation", derived by a positive feedback loop between OxS byproducts and inflammatory mediators that in a long run further aggravates the clinical features of RTT patients. Therefore, in a pathology completely orphan of any therapy, aiming 4HNE as a therapeutic target could represent a coadjuvant treatment with some beneficial impact in these patients..
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Affiliation(s)
- Giuseppe Valacchi
- Plants for Human Health Institute, Department of Animal Sciences, NC State University, NC Research Campus, 600 Laureate Way, Kannapolis, NC 28081, USA; Department of Life Sciences and Biotechnology, University of Ferrara, Via Luigi Borsari 46, 44121 Ferrara, Italy.
| | - Alessandra Pecorelli
- Plants for Human Health Institute, Department of Animal Sciences, NC State University, NC Research Campus, 600 Laureate Way, Kannapolis, NC 28081, USA; Department of Life Sciences and Biotechnology, University of Ferrara, Via Luigi Borsari 46, 44121 Ferrara, Italy
| | - Carlo Cervellati
- Department of Biomedical and Specialist Surgical Sciences, Section of Medical Biochemistry, Molecular Biology and Genetics, University of Ferrara, Via Luigi Borsari 46, 44121 Ferrara, Italy
| | - Joussef Hayek
- Child Neuropsychiatry Unit, University Hospital, AOUS, Viale Mario Bracci, 53100 Siena, Italy
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Stem Cell Technology for (Epi)genetic Brain Disorders. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 978:443-475. [PMID: 28523560 DOI: 10.1007/978-3-319-53889-1_23] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Despite the enormous efforts of the scientific community over the years, effective therapeutics for many (epi)genetic brain disorders remain unidentified. The common and persistent failures to translate preclinical findings into clinical success are partially attributed to the limited efficiency of current disease models. Although animal and cellular models have substantially improved our knowledge of the pathological processes involved in these disorders, human brain research has generally been hampered by a lack of satisfactory humanized model systems. This, together with our incomplete knowledge of the multifactorial causes in the majority of these disorders, as well as a thorough understanding of associated (epi)genetic alterations, has been impeding progress in gaining more mechanistic insights from translational studies. Over the last years, however, stem cell technology has been offering an alternative approach to study and treat human brain disorders. Owing to this technology, we are now able to obtain a theoretically inexhaustible source of human neural cells and precursors in vitro that offer a platform for disease modeling and the establishment of therapeutic interventions. In addition to the potential to increase our general understanding of how (epi)genetic alterations contribute to the pathology of brain disorders, stem cells and derivatives allow for high-throughput drugs and toxicity testing, and provide a cell source for transplant therapies in regenerative medicine. In the current chapter, we will demonstrate the validity of human stem cell-based models and address the utility of other stem cell-based applications for several human brain disorders with multifactorial and (epi)genetic bases, including Parkinson's disease (PD), Alzheimer's disease (AD), fragile X syndrome (FXS), Angelman syndrome (AS), Prader-Willi syndrome (PWS), and Rett syndrome (RTT).
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Shulyakova N, Andreazza AC, Mills LR, Eubanks JH. Mitochondrial Dysfunction in the Pathogenesis of Rett Syndrome: Implications for Mitochondria-Targeted Therapies. Front Cell Neurosci 2017; 11:58. [PMID: 28352216 PMCID: PMC5348512 DOI: 10.3389/fncel.2017.00058] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 02/20/2017] [Indexed: 01/20/2023] Open
Abstract
First described over 50 years ago, Rett syndrome (RTT) is a neurodevelopmental disorder caused primarily by mutations of the X-linked MECP2 gene. RTT affects predominantly females, and has a prevalence of roughly 1 in every 10,000 female births. Prior to the discovery that mutations of MECP2 are the leading cause of RTT, there were suggestions that RTT could be a mitochondrial disease. In fact, several reports documented altered mitochondrial structure, and deficiencies in mitochondrial enzyme activity in different cells or tissues derived from RTT patients. With the identification of MECP2 as the causal gene, interest largely shifted toward defining the normal function of MeCP2 in the brain, and how its absence affects the neurodevelopment and neurophysiology. Recently, though, interest in studying mitochondrial function in RTT has been reignited, at least in part due to observations suggesting systemic oxidative stress does play a contributing role in RTT pathogenesis. Here we review data relating to mitochondrial alterations at the structural and functional levels in RTT patients and model systems, and present a hypothesis for how the absence of MeCP2 could lead to altered mitochondrial function and elevated levels of cellular oxidative stress. Finally, we discuss the prospects for treating RTT using interventions that target specific aspects of mitochondrial dysfunction and/or oxidative stress.
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Affiliation(s)
- Natalya Shulyakova
- Division of Genetics and Development, Krembil Research Institute, University Health NetworkToronto, ON, Canada; Department of Physiology, University of TorontoToronto, ON, Canada
| | - Ana C Andreazza
- Department of Pharmacology, University of Toronto Toronto, ON, Canada
| | - Linda R Mills
- Department of Physiology, University of Toronto Toronto, ON, Canada
| | - James H Eubanks
- Division of Genetics and Development, Krembil Research Institute, University Health NetworkToronto, ON, Canada; Department of Physiology, University of TorontoToronto, ON, Canada; Institute of Medical Sciences, University of TorontoToronto, ON, Canada; Department of Surgery (Neurosurgery), University of TorontoToronto, ON, Canada
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Ip CW, Isaias IU, Kusche-Tekin BB, Klein D, Groh J, O’Leary A, Knorr S, Higuchi T, Koprich JB, Brotchie JM, Toyka KV, Reif A, Volkmann J. Tor1a+/- mice develop dystonia-like movements via a striatal dopaminergic dysregulation triggered by peripheral nerve injury. Acta Neuropathol Commun 2016; 4:108. [PMID: 27716431 PMCID: PMC5048687 DOI: 10.1186/s40478-016-0375-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 09/14/2016] [Indexed: 11/10/2022] Open
Abstract
Isolated generalized dystonia is a central motor network disorder characterized by twisted movements or postures. The most frequent genetic cause is a GAG deletion in the Tor1a (DYT1) gene encoding torsinA with a reduced penetrance of 30-40 % suggesting additional genetic or environmental modifiers. Development of dystonia-like movements after a standardized peripheral nerve crush lesion in wild type (wt) and Tor1a+/- mice, that express 50 % torsinA only, was assessed by scoring of hindlimb movements during tail suspension, by rotarod testing and by computer-assisted gait analysis. Western blot analysis was performed for dopamine transporter (DAT), D1 and D2 receptors from striatal and quantitative RT-PCR analysis for DAT from midbrain dissections. Autoradiography was used to assess the functional DAT binding in striatum. Striatal dopamine and its metabolites were analyzed by high performance liquid chromatography. After nerve crush injury, we found abnormal posturing in the lesioned hindlimb of both mutant and wt mice indicating the profound influence of the nerve lesion (15x vs. 12x relative to control) resembling human peripheral pseudodystonia. In mutant mice the phenotypic abnormalities were increased by about 40 % (p < 0.05). This was accompanied by complex alterations of striatal dopamine homeostasis. Pharmacological blockade of dopamine synthesis reduced severity of dystonia-like movements, whereas treatment with L-Dopa aggravated these but only in mutant mice suggesting a DYT1 related central component relevant to the development of abnormal involuntary movements. Our findings suggest that upon peripheral nerve injury reduced torsinA concentration and environmental stressors may act in concert in causing the central motor network dysfunction of DYT1 dystonia.
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Abstract
Dopamine, a prominent neuromodulator, is implicated in many neuropsychiatric disorders. It has wide-ranging effects on both cortical and subcortical brain regions and on many types of cognitive tasks that rely on a variety of different learning and memory systems. As neuroscience and behavioral evidence for the existence of multiple memory systems and their corresponding neural networks accumulated, so did the notion that dopamine's role is markedly different depending on which memory system is engaged. As a result, dopamine-directed treatments will have different effects on different types of cognitive behaviors. To predict what these effects will be, it is critical to understand: which memory system is mediating the behavior; the neural basis of the mediating memory system; the nature of the dopamine projections into that system; and the time course of dopamine after its release into the relevant brain regions. Consideration of these questions leads to different predictions for how changes in brain dopamine levels will affect automatic behaviors and behaviors mediated by declarative, procedural, and perceptual representation memory systems.
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Affiliation(s)
- F Gregory Ashby
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA, USA
| | - Vivian V Valentin
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA, USA
| | - Stella S von Meer
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA, USA
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Deficient Purposeful Use of Forepaws in Female Mice Modelling Rett Syndrome. Neural Plast 2015; 2015:326184. [PMID: 26185689 PMCID: PMC4491574 DOI: 10.1155/2015/326184] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Revised: 05/21/2015] [Accepted: 05/24/2015] [Indexed: 12/31/2022] Open
Abstract
Rett syndrome (RTT) is a rare neurodevelopmental disorder, characterized by severe behavioural and physiological symptoms. Mutations in the methyl CpG binding protein 2 gene (MECP2) cause more than 95% of classic cases. Motor abnormalities represent a significant part of the spectrum of RTT symptoms. In the present study we investigated motor coordination and fine motor skill domains in MeCP2-308 female mice, a validated RTT model. This was complemented by the in vivo magnetic resonance spectroscopy (MRS) analysis of metabolic profile in behaviourally relevant brain areas. MeCP2-308 heterozygous female mice (Het, 10-12 months of age) were impaired in tasks validated for the assessment of purposeful and coordinated forepaw use (Morag test and Capellini handling task). A fine-grain analysis of spontaneous behaviour in the home-cage also revealed an abnormal handling pattern when interacting with the nesting material, reduced motivation to explore the environment, and increased time devoted to feeding in Het mice. The brain MRS evaluation highlighted decreased levels of bioenergetic metabolites in the striatal area in Het mice compared to controls. Present results confirm behavioural and brain alterations previously reported in MeCP2-308 males and identify novel endpoints on which the efficacy of innovative therapeutic strategies for RTT may be tested.
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