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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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2
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Nguyen L. Updates on Disease Mechanisms and Therapeutics for Amyotrophic Lateral Sclerosis. Cells 2024; 13:888. [PMID: 38891021 PMCID: PMC11172142 DOI: 10.3390/cells13110888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2024] [Revised: 05/08/2024] [Accepted: 05/15/2024] [Indexed: 06/20/2024] Open
Abstract
Amyotrophic lateral sclerosis (ALS), or Lou Gehrig's disease, is a motor neuron disease. In ALS, upper and lower motor neurons in the brain and spinal cord progressively degenerate during the course of the disease, leading to the loss of the voluntary movement of the arms and legs. Since its first description in 1869 by a French neurologist Jean-Martin Charcot, the scientific discoveries on ALS have increased our understanding of ALS genetics, pathology and mechanisms and provided novel therapeutic strategies. The goal of this review article is to provide a comprehensive summary of the recent findings on ALS mechanisms and related therapeutic strategies to the scientific audience. Several highlighted ALS research topics discussed in this article include the 2023 FDA approved drug for SOD1 ALS, the updated C9orf72 GGGGCC repeat-expansion-related mechanisms and therapeutic targets, TDP-43-mediated cryptic splicing and disease markers and diagnostic and therapeutic options offered by these recent discoveries.
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Affiliation(s)
- Lien Nguyen
- Department of Molecular Genetics and Microbiology, College of Medicine, University of Florida, Gainesville, FL 32610, USA;
- Center for NeuroGenetics, College of Medicine, University of Florida, Gainesville, FL 32610, USA
- Department of Neuroscience, College of Medicine, University of Florida, Gainesville, FL 32610, USA
- Genetics Institute, University of Florida, Gainesville, FL 32610, USA
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3
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Zhong R, Rua MT, Wei-LaPierre L. Targeting mitochondrial Ca 2+ uptake for the treatment of amyotrophic lateral sclerosis. J Physiol 2024; 602:1519-1549. [PMID: 38010626 PMCID: PMC11032238 DOI: 10.1113/jp284143] [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: 09/06/2023] [Accepted: 10/31/2023] [Indexed: 11/29/2023] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a rare adult-onset neurodegenerative disease characterized by progressive motor neuron (MN) loss, muscle denervation and paralysis. Over the past several decades, researchers have made tremendous efforts to understand the pathogenic mechanisms underpinning ALS, with much yet to be resolved. ALS is described as a non-cell autonomous condition with pathology detected in both MNs and non-neuronal cells, such as glial cells and skeletal muscle. Studies in ALS patient and animal models reveal ubiquitous abnormalities in mitochondrial structure and function, and disturbance of intracellular calcium homeostasis in various tissue types, suggesting a pivotal role of aberrant mitochondrial calcium uptake and dysfunctional calcium signalling cascades in ALS pathogenesis. Calcium signalling and mitochondrial dysfunction are intricately related to the manifestation of cell death contributing to MN loss and skeletal muscle dysfunction. In this review, we discuss the potential contribution of intracellular calcium signalling, particularly mitochondrial calcium uptake, in ALS pathogenesis. Functional consequences of excessive mitochondrial calcium uptake and possible therapeutic strategies targeting mitochondrial calcium uptake or the mitochondrial calcium uniporter, the main channel mediating mitochondrial calcium influx, are also discussed.
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Affiliation(s)
- Renjia Zhong
- Department of Applied Physiology and Kinesiology, College of Health and Human Performance, University of Florida, Gainesville, FL, 32611
- Department of Emergency Medicine, the First Affiliated Hospital of China Medical University, Shenyang, Liaoning, China, 110001
| | - Michael T. Rua
- Department of Applied Physiology and Kinesiology, College of Health and Human Performance, University of Florida, Gainesville, FL, 32611
| | - Lan Wei-LaPierre
- Department of Applied Physiology and Kinesiology, College of Health and Human Performance, University of Florida, Gainesville, FL, 32611
- Myology Institute, University of Florida, Gainesville, FL 32611
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4
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Liang Z, Ralph-Epps T, Schmidtke MW, Kumar V, Greenberg ML. Decreased pyruvate dehydrogenase activity in Tafazzin-deficient cells is caused by dysregulation of pyruvate dehydrogenase phosphatase 1 (PDP1). J Biol Chem 2024; 300:105697. [PMID: 38301889 PMCID: PMC10884759 DOI: 10.1016/j.jbc.2024.105697] [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: 11/15/2023] [Revised: 01/13/2024] [Accepted: 01/19/2024] [Indexed: 02/03/2024] Open
Abstract
Cardiolipin (CL), the signature lipid of the mitochondrial inner membrane, is critical for maintaining optimal mitochondrial function and bioenergetics. Disruption of CL metabolism, caused by mutations in the CL remodeling enzyme TAFAZZIN, results in the life-threatening disorder Barth syndrome (BTHS). While the clinical manifestations of BTHS, such as dilated cardiomyopathy and skeletal myopathy, point to defects in mitochondrial bioenergetics, the disorder is also characterized by broad metabolic dysregulation, including abnormal levels of metabolites associated with the tricarboxylic acid (TCA) cycle. Recent studies have identified the inhibition of pyruvate dehydrogenase (PDH), the gatekeeper enzyme for TCA cycle carbon influx, as a key deficiency in various BTHS model systems. However, the molecular mechanisms linking aberrant CL remodeling, particularly the primary, direct consequence of reduced tetralinoleoyl-CL (TLCL) levels, to PDH activity deficiency are not yet understood. In the current study, we found that remodeled TLCL promotes PDH function by directly binding to and enhancing the activity of PDH phosphatase 1 (PDP1). This is supported by our findings that TLCL uniquely activates PDH in a dose-dependent manner, TLCL binds to PDP1 in vitro, TLCL-mediated PDH activation is attenuated in the presence of phosphatase inhibitor, and PDP1 activity is decreased in Tafazzin-knockout (TAZ-KO) C2C12 myoblasts. Additionally, we observed decreased mitochondrial calcium levels in TAZ-KO cells and treating TAZ-KO cells with calcium lactate (CaLac) increases mitochondrial calcium and restores PDH activity and mitochondrial oxygen consumption rate. Based on our findings, we conclude that reduced mitochondrial calcium levels and decreased binding of PDP1 to TLCL contribute to decreased PDP1 activity in TAZ-KO cells.
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Affiliation(s)
- Zhuqing Liang
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
| | - Tyler Ralph-Epps
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
| | - Michael W Schmidtke
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
| | - Vikalp Kumar
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
| | - Miriam L Greenberg
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA.
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5
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Markovinovic A, Martín-Guerrero SM, Mórotz GM, Salam S, Gomez-Suaga P, Paillusson S, Greig J, Lee Y, Mitchell JC, Noble W, Miller CCJ. Stimulating VAPB-PTPIP51 ER-mitochondria tethering corrects FTD/ALS mutant TDP43 linked Ca 2+ and synaptic defects. Acta Neuropathol Commun 2024; 12:32. [PMID: 38395965 PMCID: PMC10885568 DOI: 10.1186/s40478-024-01742-x] [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: 09/20/2023] [Accepted: 02/05/2024] [Indexed: 02/25/2024] Open
Abstract
Frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) are clinically linked major neurodegenerative diseases. Notably, TAR DNA-binding protein-43 (TDP43) accumulations are hallmark pathologies of FTD/ALS and mutations in the gene encoding TDP43 cause familial FTD/ALS. There are no cures for FTD/ALS. FTD/ALS display damage to a broad range of physiological functions, many of which are regulated by signaling between the endoplasmic reticulum (ER) and mitochondria. This signaling is mediated by the VAPB-PTPIP51 tethering proteins that serve to recruit regions of ER to the mitochondrial surface so as to facilitate inter-organelle communications. Several studies have now shown that disrupted ER-mitochondria signaling including breaking of the VAPB-PTPIP51 tethers are features of FTD/ALS and that for TDP43 and other familial genetic FTD/ALS insults, this involves activation of glycogen kinase-3β (GSK3β). Such findings have prompted suggestions that correcting damage to ER-mitochondria signaling and the VAPB-PTPIP51 interaction may be broadly therapeutic. Here we provide evidence to support this notion. We show that overexpression of VAPB or PTPIP51 to enhance ER-mitochondria signaling corrects mutant TDP43 induced damage to inositol 1,4,5-trisphosphate (IP3) receptor delivery of Ca2+ to mitochondria which is a primary function of the VAPB-PTPIP51 tethers, and to synaptic function. Moreover, we show that ursodeoxycholic acid (UDCA), an FDA approved drug linked to FTD/ALS and other neurodegenerative diseases therapy and whose precise therapeutic target is unclear, corrects TDP43 linked damage to the VAPB-PTPIP51 interaction. We also show that this effect involves inhibition of TDP43 mediated activation of GSK3β. Thus, correcting damage to the VAPB-PTPIP51 tethers may have therapeutic value for FTD/ALS and other age-related neurodegenerative diseases.
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Affiliation(s)
- Andrea Markovinovic
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, SE5 9RX, London, UK.
| | - Sandra M Martín-Guerrero
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, SE5 9RX, London, UK
| | - Gábor M Mórotz
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, SE5 9RX, London, UK
| | - Shaakir Salam
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, SE5 9RX, London, UK
| | - Patricia Gomez-Suaga
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, SE5 9RX, London, UK
| | - Sebastien Paillusson
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, SE5 9RX, London, UK
| | - Jenny Greig
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, SE5 9RX, London, UK
| | - Younbok Lee
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, SE5 9RX, London, UK
| | - Jacqueline C Mitchell
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, SE5 9RX, London, UK
| | - Wendy Noble
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, SE5 9RX, London, UK
| | - Christopher C J Miller
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, SE5 9RX, London, UK.
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6
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Dellar ER, Vendrell I, Talbot K, Kessler BM, Fischer R, Turner MR, Thompson AG. Data-independent acquisition proteomics of cerebrospinal fluid implicates endoplasmic reticulum and inflammatory mechanisms in amyotrophic lateral sclerosis. J Neurochem 2024; 168:115-127. [PMID: 38087504 PMCID: PMC10952667 DOI: 10.1111/jnc.16030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 11/29/2023] [Accepted: 12/02/2023] [Indexed: 01/26/2024]
Abstract
While unbiased proteomics of human cerebrospinal fluid (CSF) has been used successfully to identify biomarkers of amyotrophic lateral sclerosis (ALS), high-abundance proteins mask the presence of lower abundance proteins that may have diagnostic and prognostic value. However, developments in mass spectrometry (MS) proteomic data acquisition methods offer improved protein depth. In this study, MS with library-free data-independent acquisition (DIA) was used to compare the CSF proteome of people with ALS (n = 40), healthy (n = 15) and disease (n = 8) controls. Quantified protein groups were subsequently correlated with clinical variables. Univariate analysis identified 7 proteins, all significantly upregulated in ALS versus healthy controls, and 9 with altered abundance in ALS versus disease controls (FDR < 0.1). Elevated chitotriosidase-1 (CHIT1) was common to both comparisons and was proportional to ALS disability progression rate (Pearson r = 0.41, FDR-adjusted p = 0.035) but not overall survival. Ubiquitin carboxyl-terminal hydrolase isozyme L1 (UCHL1; upregulated in ALS versus healthy controls) was proportional to disability progression rate (Pearson r = 0.53, FDR-adjusted p = 0.003) and survival (Kaplan Meier log-rank p = 0.013) but not independently in multivariate proportional hazards models. Weighted correlation network analysis was used to identify functionally relevant modules of proteins. One module, enriched for inflammatory functions, was associated with age at symptom onset (Pearson r = 0.58, FDR-adjusted p = 0.005) and survival (Hazard Ratio = 1.78, FDR = 0.065), and a second module, enriched for endoplasmic reticulum proteins, was negatively correlated with disability progression rate (r = -0.42, FDR-adjusted p = 0.109). DIA acquisition methodology therefore strengthened the biomarker candidacy of CHIT1 and UCHL1 in ALS, while additionally highlighted inflammatory and endoplasmic reticulum proteins as novel sources of prognostic biomarkers.
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Affiliation(s)
| | - Iolanda Vendrell
- Centre for Medicines Discovery, Nuffield Department of Medicine, Target Discovery InstituteUniversity of OxfordOxfordUK
- Nuffield Department of Medicine, Chinese Academy of Medical Sciences Oxford InstituteUniversity of OxfordOxfordUK
| | - Kevin Talbot
- Nuffield Department of Clinical NeurosciencesUniversity of OxfordOxfordUK
- Kavli Institute for Nanoscience DiscoveryUniversity of OxfordOxfordUK
| | - Benedikt M. Kessler
- Centre for Medicines Discovery, Nuffield Department of Medicine, Target Discovery InstituteUniversity of OxfordOxfordUK
- Nuffield Department of Medicine, Chinese Academy of Medical Sciences Oxford InstituteUniversity of OxfordOxfordUK
| | - Roman Fischer
- Centre for Medicines Discovery, Nuffield Department of Medicine, Target Discovery InstituteUniversity of OxfordOxfordUK
- Nuffield Department of Medicine, Chinese Academy of Medical Sciences Oxford InstituteUniversity of OxfordOxfordUK
| | - Martin R. Turner
- Nuffield Department of Clinical NeurosciencesUniversity of OxfordOxfordUK
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7
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Cunha-Oliveira T, Montezinho L, Simões RF, Carvalho M, Ferreiro E, Silva FSG. Mitochondria: A Promising Convergent Target for the Treatment of Amyotrophic Lateral Sclerosis. Cells 2024; 13:248. [PMID: 38334639 PMCID: PMC10854804 DOI: 10.3390/cells13030248] [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: 12/07/2023] [Revised: 01/18/2024] [Accepted: 01/24/2024] [Indexed: 02/10/2024] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease characterized by the progressive loss of motor neurons, for which current treatment options are limited. Recent studies have shed light on the role of mitochondria in ALS pathogenesis, making them an attractive therapeutic intervention target. This review contains a very comprehensive critical description of the involvement of mitochondria and mitochondria-mediated mechanisms in ALS. The review covers several key areas related to mitochondria in ALS, including impaired mitochondrial function, mitochondrial bioenergetics, reactive oxygen species, metabolic processes and energy metabolism, mitochondrial dynamics, turnover, autophagy and mitophagy, impaired mitochondrial transport, and apoptosis. This review also highlights preclinical and clinical studies that have investigated various mitochondria-targeted therapies for ALS treatment. These include strategies to improve mitochondrial function, such as the use of dichloroacetate, ketogenic and high-fat diets, acetyl-carnitine, and mitochondria-targeted antioxidants. Additionally, antiapoptotic agents, like the mPTP-targeting agents minocycline and rasagiline, are discussed. The paper aims to contribute to the identification of effective mitochondria-targeted therapies for ALS treatment by synthesizing the current understanding of the role of mitochondria in ALS pathogenesis and reviewing potential convergent therapeutic interventions. The complex interplay between mitochondria and the pathogenic mechanisms of ALS holds promise for the development of novel treatment strategies to combat this devastating disease.
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Affiliation(s)
- Teresa Cunha-Oliveira
- CNC—Center for Neuroscience and Cell Biology, CIBB—Centre for Innovative Biomedicine and Biotechnology, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Liliana Montezinho
- Center for Investigation Vasco da Gama (CIVG), Escola Universitária Vasco da Gama, 3020-210 Coimbra, Portugal;
| | - Rui F. Simões
- CNC—Center for Neuroscience and Cell Biology, CIBB—Centre for Innovative Biomedicine and Biotechnology, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Marcelo Carvalho
- CNC—Center for Neuroscience and Cell Biology, CIBB—Centre for Innovative Biomedicine and Biotechnology, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Elisabete Ferreiro
- CNC—Center for Neuroscience and Cell Biology, CIBB—Centre for Innovative Biomedicine and Biotechnology, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Filomena S. G. Silva
- CNC—Center for Neuroscience and Cell Biology, CIBB—Centre for Innovative Biomedicine and Biotechnology, University of Coimbra, 3004-504 Coimbra, Portugal
- Mitotag Lda, Biocant Park, 3060-197 Cantanhede, Portugal
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8
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Smeele PH, Cesare G, Vaccari T. ALS' Perfect Storm: C9orf72-Associated Toxic Dipeptide Repeats as Potential Multipotent Disruptors of Protein Homeostasis. Cells 2024; 13:178. [PMID: 38247869 PMCID: PMC10813877 DOI: 10.3390/cells13020178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 01/10/2024] [Accepted: 01/12/2024] [Indexed: 01/23/2024] Open
Abstract
Protein homeostasis is essential for neuron longevity, requiring a balanced regulation between protein synthesis and degradation. The clearance of misfolded and aggregated proteins, mediated by autophagy and the ubiquitin-proteasome systems, maintains protein homeostasis in neurons, which are post-mitotic and thus cannot use cell division to diminish the burden of misfolded proteins. When protein clearance pathways are overwhelmed or otherwise disrupted, the accumulation of misfolded or aggregated proteins can lead to the activation of ER stress and the formation of stress granules, which predominantly attempt to restore the homeostasis by suppressing global protein translation. Alterations in these processes have been widely reported among studies investigating the toxic function of dipeptide repeats (DPRs) produced by G4C2 expansion in the C9orf72 gene of patients with amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). In this review, we outline the modalities of DPR-induced disruptions in protein homeostasis observed in a wide range of models of C9orf72-linked ALS/FTD. We also discuss the relative importance of each DPR for toxicity, possible synergies between DPRs, and discuss the possible functional relevance of DPR aggregation to disease pathogenesis. Finally, we highlight the interdependencies of the observed effects and reflect on the importance of feedback and feedforward mechanisms in their contribution to disease progression. A better understanding of DPR-associated disease pathogenesis discussed in this review might shed light on disease vulnerabilities that may be amenable with therapeutic interventions.
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Affiliation(s)
| | | | - Thomas Vaccari
- Department of Biosciences, University of Milan, Via Celoria 26, 20133 Milan, Italy
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Sierra-Delgado JA, Sinha-Ray S, Kaleem A, Ganjibakhsh M, Parvate M, Powers S, Zhang X, Likhite S, Meyer K. In Vitro Modeling as a Tool for Testing Therapeutics for Spinal Muscular Atrophy and IGHMBP2-Related Disorders. BIOLOGY 2023; 12:867. [PMID: 37372153 DOI: 10.3390/biology12060867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 06/08/2023] [Accepted: 06/12/2023] [Indexed: 06/29/2023]
Abstract
Spinal Muscular Atrophy (SMA) is the leading genetic cause of infant mortality. The most common form of SMA is caused by mutations in the SMN1 gene, located on 5q (SMA). On the other hand, mutations in IGHMBP2 lead to a large disease spectrum with no clear genotype-phenotype correlation, which includes Spinal Muscular Atrophy with Muscular Distress type 1 (SMARD1), an extremely rare form of SMA, and Charcot-Marie-Tooth 2S (CMT2S). We optimized a patient-derived in vitro model system that allows us to expand research on disease pathogenesis and gene function, as well as test the response to the AAV gene therapies we have translated to the clinic. We generated and characterized induced neurons (iN) from SMA and SMARD1/CMT2S patient cell lines. After establishing the lines, we treated the generated neurons with AAV9-mediated gene therapy (AAV9.SMN (Zolgensma) for SMA and AAV9.IGHMBP2 for IGHMBP2 disorders (NCT05152823)) to evaluate the response to treatment. The iNs of both diseases show a characteristic short neurite length and defects in neuronal conversion, which have been reported in the literature before with iPSC modeling. SMA iNs respond to treatment with AAV9.SMN in vitro, showing a partial rescue of the morphology phenotype. For SMARD1/CMT2S iNs, we were able to observe an improvement in the neurite length of neurons after the restoration of IGHMBP2 in all disease cell lines, albeit to a variable extent, with some lines showing better responses to treatment than others. Moreover, this protocol allowed us to classify a variant of uncertain significance on IGHMBP2 on a suspected SMARD1/CMT2S patient. This study will further the understanding of SMA, and SMARD1/CMT2S disease in particular, in the context of variable patient mutations, and might further the development of new treatments, which are urgently needed.
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Affiliation(s)
| | - Shrestha Sinha-Ray
- The Research Institute at Nationwide Children's Hospital, Columbus, OH 43205, USA
| | - Abuzar Kaleem
- The Research Institute at Nationwide Children's Hospital, Columbus, OH 43205, USA
| | - Meysam Ganjibakhsh
- The Research Institute at Nationwide Children's Hospital, Columbus, OH 43205, USA
| | - Mohini Parvate
- The Research Institute at Nationwide Children's Hospital, Columbus, OH 43205, USA
| | - Samantha Powers
- The Research Institute at Nationwide Children's Hospital, Columbus, OH 43205, USA
| | - Xiaojin Zhang
- The Research Institute at Nationwide Children's Hospital, Columbus, OH 43205, USA
| | - Shibi Likhite
- The Research Institute at Nationwide Children's Hospital, Columbus, OH 43205, USA
| | - Kathrin Meyer
- The Research Institute at Nationwide Children's Hospital, Columbus, OH 43205, USA
- College of Medicine, The Ohio State University, Columbus, OH 43205, USA
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