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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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Jagadeeswaran I, Oh J, Sinnett SE. Preclinical Milestones in MECP2 Gene Transfer for Treating Rett Syndrome. Dev Neurosci 2024:1-10. [PMID: 38723617 DOI: 10.1159/000539267] [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: 02/15/2024] [Accepted: 05/06/2024] [Indexed: 06/28/2024] Open
Abstract
BACKGROUND Rett syndrome (RTT) is a neurodevelopmental disorder caused by mutations in the transcriptional regulator methyl-CpG-binding protein 2 (MeCP2). After gene transfer in mice, exogenous MeCP2 expression must be regulated to avoid dose-dependent toxicity. SUMMARY The preclinical gene therapy literature for treating RTT illustrates a duly diligent progression that begins with proof-of-concept studies and advances toward the development of safer, regulated MECP2 viral genome designs. This design progression was partly achieved through international collaborative studies. In 2023, clinicians administered investigational gene therapies for RTT to patients a decade after the first preclinical gene therapy publications for RTT (clinical trial numbers NCT05606614 and NCT05898620). As clinicians take on a more prominent role in MECP2 gene therapy research, preclinical researchers may continue to test more nuanced hypotheses regarding the safety, efficacy, and mechanism of MECP2 gene transfer. KEY MESSAGE This review summarizes the history of preclinical MECP2 gene transfer for treating RTT and acknowledges major contributions among colleagues in the field. The first clinical injections are a shared milestone.
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Affiliation(s)
- Indumathy Jagadeeswaran
- Department of Pediatrics, The University of Texas Southwestern Medical Center (UTSWMC), Dallas, Texas, USA,
| | - Jiyoung Oh
- Department of Pediatrics, The University of Texas Southwestern Medical Center (UTSWMC), Dallas, Texas, USA
| | - Sarah E Sinnett
- Department of Pediatrics, The University of Texas Southwestern Medical Center (UTSWMC), Dallas, Texas, USA
- Eugene McDermott Center for Human Growth and Development, The University of Texas Southwestern Medical Center (UTSWMC), Dallas, Texas, USA
- Peter O'Donnell Jr. Brain Institute, The University of Texas Southwestern Medical Center (UTSWMC), Dallas, Texas, USA
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Merritt JK, Fang X, Caylor RC, Skinner SA, Friez MJ, Percy AK, Neul JL. Normalized Clinical Severity Scores Reveal a Correlation between X Chromosome Inactivation and Disease Severity in Rett Syndrome. Genes (Basel) 2024; 15:594. [PMID: 38790223 PMCID: PMC11120815 DOI: 10.3390/genes15050594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2024] [Revised: 05/01/2024] [Accepted: 05/05/2024] [Indexed: 05/26/2024] Open
Abstract
Rett Syndrome (RTT) is a severe neurodevelopmental disorder predominately diagnosed in females and primarily caused by pathogenic variants in the X-linked gene Methyl-CpG Binding Protein 2 (MECP2). Most often, the disease causing the MECP2 allele resides on the paternal X chromosome while a healthy copy is maintained on the maternal X chromosome with inactivation (XCI), resulting in mosaic expression of one allele in each cell. Preferential inactivation of the paternal X chromosome is theorized to result in reduced disease severity; however, establishing such a correlation is complicated by known MECP2 genotype effects and an age-dependent increase in severity. To mitigate these confounding factors, we developed an age- and genotype-normalized measure of RTT severity by modeling longitudinal data collected in the US Rett Syndrome Natural History Study. This model accurately reflected individual increase in severity with age and preserved group-level genotype specific differences in severity, allowing for the creation of a normalized clinical severity score. Applying this normalized score to a RTT XCI dataset revealed that XCI influence on disease severity depends on MECP2 genotype with a correlation between XCI and severity observed only in individuals with MECP2 variants associated with increased clinical severity. This normalized measure of RTT severity provides the opportunity for future discovery of additional factors contributing to disease severity that may be masked by age and genotype effects.
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Affiliation(s)
- Jonathan K. Merritt
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232, USA;
| | - Xiaolan Fang
- Department of Pathology, Henry Ford Health System, Detroit, MI 48202, USA;
- Greenwood Genetic Center, Greenwood, SC 29646, USA; (R.C.C.); (S.A.S.); (M.J.F.)
| | - Raymond C. Caylor
- Greenwood Genetic Center, Greenwood, SC 29646, USA; (R.C.C.); (S.A.S.); (M.J.F.)
| | - Steven A. Skinner
- Greenwood Genetic Center, Greenwood, SC 29646, USA; (R.C.C.); (S.A.S.); (M.J.F.)
| | - Michael J. Friez
- Greenwood Genetic Center, Greenwood, SC 29646, USA; (R.C.C.); (S.A.S.); (M.J.F.)
| | - Alan K. Percy
- Department of Pediatrics, University of Alabama at Birmingham, Birmingham, AL 35294, USA;
| | - Jeffrey L. Neul
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232, USA;
- Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA
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Flynn MJ, Mayfield AM, Du R, Gradinaru V, Elowitz MB. Synthetic dosage-compensating miRNA circuits allow precision gene therapy for Rett syndrome. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.13.584179. [PMID: 38559034 PMCID: PMC10980028 DOI: 10.1101/2024.03.13.584179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
A longstanding challenge in gene therapy is expressing a dosage-sensitive gene within a tight therapeutic window. For example, loss of MECP2 function causes Rett syndrome, while its duplication causes MECP2 duplication syndrome. Viral gene delivery methods generate variable numbers of gene copies in individual cells, creating a need for gene dosage-invariant expression systems. Here, we introduce a compact miRNA-based, incoherent feed-forward loop circuit that achieves precise control of Mecp2 expression in cells and brains, and improves outcomes in an AAV-based mouse model of Rett syndrome gene therapy. Single molecule analysis of endogenous and ectopic Mecp2 mRNA revealed precise, sustained expression across a broad range of gene dosages. Delivered systemically in a brain-targeting AAV capsid, the circuit strongly suppressed Rett behavioral symptoms for over 24 weeks, outperforming an unregulated gene therapy. These results demonstrate that synthetic miRNA-based regulatory circuits can enable precise in vivo expression to improve the safety and efficacy of gene therapy.
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Affiliation(s)
- Michael J. Flynn
- Division of Engineering and Applied Sciences, California Institute of Technology, Pasadena, CA 91125
| | - Acacia M.H. Mayfield
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125
| | - Rongrong Du
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125
| | - Viviana Gradinaru
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125
| | - Michael B. Elowitz
- Division of Engineering and Applied Sciences, California Institute of Technology, Pasadena, CA 91125
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125
- Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA 91125
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Sadhu C, Lyons C, Oh J, Jagadeeswaran I, Gray SJ, Sinnett SE. The Efficacy of a Human-Ready mini MECP2 Gene Therapy in a Pre-Clinical Model of Rett Syndrome. Genes (Basel) 2023; 15:31. [PMID: 38254921 PMCID: PMC10815157 DOI: 10.3390/genes15010031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Revised: 12/18/2023] [Accepted: 12/19/2023] [Indexed: 01/24/2024] Open
Abstract
Inactivating mutations and the duplication of methyl-CpG binding protein 2 (MeCP2), respectively, mediate Rett syndrome (RTT) and MECP2 duplication syndrome. These disorders underscore the conceptual dose-dependent risk posed by MECP2 gene therapy for mosaic RTT patients. Recently, a miRNA-Responsive Autoregulatory Element (miRARE) mitigated the dose-dependent toxicity posed by self-complementary adeno-associated viral vector serotype 9 (AAV9) miniMECP2 gene therapy (scAAV9/miniMECP2-myc) in mice. Here, we report an efficacy assessment for the human-ready version of this regulated gene therapy (TSHA-102) in male Mecp2-/y knockout (KO) mice after intracerebroventricular (ICV) administration at postnatal day 2 (P2) and after intrathecal (IT) administration at P7, P14 (±immunosuppression), and P28 (±immunosuppression). We also report qPCR studies on KO mice treated at P7-P35; protein analyses in KO mice treated at P38; and a survival safety study in female adult Mecp2-/+ mice. In KO mice, TSHA-102 improved respiration, weight, and survival across multiple doses and treatment ages. TSHA-102 significantly improved the front average stance and swing times relative to the front average stride time after P14 administration of the highest dose for that treatment age. Viral genomic DNA and miniMECP2 mRNA were present in the CNS. MiniMeCP2 protein expression was higher in the KO spinal cord compared to the brain. In female mice, TSHA-102 permitted survivals that were similar to those of vehicle-treated controls. In all, these pivotal data helped to support the regulatory approval to initiate a clinical trial for TSHA-102 in RTT patients (clinical trial identifier number NCT05606614).
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Affiliation(s)
- Chanchal Sadhu
- Formerly of Taysha Gene Therapies, Dallas, TX 75247, USA
| | - Christopher Lyons
- Formerly of the Department of Pediatrics, University of Texas Southwestern Medical Center (UTSWMC), Dallas, TX 75390, USA
| | - Jiyoung Oh
- Department of Pediatrics, University of Texas Southwestern Medical Center (UTSWMC), Dallas, TX 75390, USA
| | - Indumathy Jagadeeswaran
- Department of Pediatrics, University of Texas Southwestern Medical Center (UTSWMC), Dallas, TX 75390, USA
| | - Steven J. Gray
- Department of Pediatrics, University of Texas Southwestern Medical Center (UTSWMC), Dallas, TX 75390, USA
- Eugene McDermott Center for Human Growth and Development, University of Texas Southwestern Medical Center (UTSWMC), Dallas, TX 75390, USA
- Peter O’Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center (UTSWMC), Dallas, TX 75390, USA
| | - Sarah E. Sinnett
- Department of Pediatrics, University of Texas Southwestern Medical Center (UTSWMC), Dallas, TX 75390, USA
- Eugene McDermott Center for Human Growth and Development, University of Texas Southwestern Medical Center (UTSWMC), Dallas, TX 75390, USA
- Peter O’Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center (UTSWMC), Dallas, TX 75390, USA
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