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Velasco-Estevez M, Gadalla KKE, Liñan-Barba N, Cobb S, Dev KK, Sheridan GK. Inhibition of Piezo1 attenuates demyelination in the central nervous system. Glia 2019; 68:356-375. [PMID: 31596529 DOI: 10.1002/glia.23722] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 08/15/2019] [Accepted: 09/06/2019] [Indexed: 12/12/2022]
Abstract
Piezo1 is a mechanosensitive ion channel that facilitates the translation of extracellular mechanical cues to intracellular molecular signaling cascades through a process termed, mechanotransduction. In the central nervous system (CNS), mechanically gated ion channels are important regulators of neurodevelopmental processes such as axon guidance, neural stem cell differentiation, and myelination of axons by oligodendrocytes. Here, we present evidence that pharmacologically mediated overactivation of Piezo1 channels negatively regulates CNS myelination. Moreover, we found that the peptide GsMTx4, an antagonist of mechanosensitive cation channels such as Piezo1, is neuroprotective and prevents chemically induced demyelination. In contrast, the positive modulator of Piezo1 channel opening, Yoda-1, induces demyelination and neuronal damage. Using an ex vivo murine-derived organotypic cerebellar slice culture model, we demonstrate that GsMTx4 attenuates demyelination induced by the cytotoxic lipid, psychosine. Importantly, we confirmed the potential therapeutic effects of GsMTx4 peptide in vivo by co-administering it with lysophosphatidylcholine (LPC), via stereotactic injection, into the cerebral cortex of adult mice. GsMTx4 prevented both demyelination and neuronal damage usually caused by the intracortical injection of LPC in vivo; a well-characterized model of focal demyelination. GsMTx4 also attenuated both LPC-induced astrocyte toxicity and microglial reactivity within the lesion core. Overall, our data suggest that pharmacological activation of Piezo1 channels induces demyelination and that inhibition of mechanosensitive channels, using GsMTx4, may alleviate the secondary progressive neurodegeneration often present in the latter stages of demyelinating diseases.
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Affiliation(s)
- María Velasco-Estevez
- Drug Development, School of Medicine, Trinity College Dublin, Dublin, Ireland.,School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, UK
| | - Kamal K E Gadalla
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, UK
| | - Núria Liñan-Barba
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, UK
| | - Stuart Cobb
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, UK
| | - Kumlesh K Dev
- Drug Development, School of Medicine, Trinity College Dublin, Dublin, Ireland
| | - Graham K Sheridan
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, UK.,School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham, UK
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Tillotson R, Selfridge J, Koerner MV, Gadalla KKE, Guy J, De Sousa D, Hector RD, Cobb SR, Bird A. Radically truncated MeCP2 rescues Rett syndrome-like neurological defects. Nature 2017; 550:398-401. [PMID: 29019980 PMCID: PMC5884422 DOI: 10.1038/nature24058] [Citation(s) in RCA: 100] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 09/05/2017] [Indexed: 12/15/2022]
Abstract
Heterozygous mutations in the X-linked MECP2 gene cause the neurological disorder Rett syndrome. The methyl-CpG-binding protein 2 (MeCP2) protein is an epigenetic reader whose binding to chromatin primarily depends on 5-methylcytosine. Functionally, MeCP2 has been implicated in several cellular processes on the basis of its reported interaction with more than 40 binding partners, including transcriptional co-repressors (for example, the NCoR/SMRT complex), transcriptional activators, RNA, chromatin remodellers, microRNA-processing proteins and splicing factors. Accordingly, MeCP2 has been cast as a multi-functional hub that integrates diverse processes that are essential in mature neurons. At odds with the concept of broad functionality, missense mutations that cause Rett syndrome are concentrated in two discrete clusters coinciding with interaction sites for partner macromolecules: the methyl-CpG binding domain and the NCoR/SMRT interaction domain. Here we test the hypothesis that the single dominant function of MeCP2 is to physically connect DNA with the NCoR/SMRT complex, by removing almost all amino-acid sequences except the methyl-CpG binding and NCoR/SMRT interaction domains. We find that mice expressing truncated MeCP2 lacking both the N- and C-terminal regions (approximately half of the native protein) are phenotypically near-normal; and those expressing a minimal MeCP2 additionally lacking a central domain survive for over one year with only mild symptoms. This minimal protein is able to prevent or reverse neurological symptoms when introduced into MeCP2-deficient mice by genetic activation or virus-mediated delivery to the brain. Thus, despite evolutionary conservation of the entire MeCP2 protein sequence, the DNA and co-repressor binding domains alone are sufficient to avoid Rett syndrome-like defects and may therefore have therapeutic utility.
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Affiliation(s)
- Rebekah Tillotson
- The Wellcome Centre for Cell Biology, University of Edinburgh, Michael Swann Building, King’s Buildings, Max Born Crescent, Edinburgh, EH9 3BF, UK
| | - Jim Selfridge
- The Wellcome Centre for Cell Biology, University of Edinburgh, Michael Swann Building, King’s Buildings, Max Born Crescent, Edinburgh, EH9 3BF, UK
| | - Martha V. Koerner
- The Wellcome Centre for Cell Biology, University of Edinburgh, Michael Swann Building, King’s Buildings, Max Born Crescent, Edinburgh, EH9 3BF, UK
| | - Kamal K. E. Gadalla
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
- Pharmacology Department, Faculty of Medicine, Tanta University, Tanta 31527, Egypt
| | - Jacky Guy
- The Wellcome Centre for Cell Biology, University of Edinburgh, Michael Swann Building, King’s Buildings, Max Born Crescent, Edinburgh, EH9 3BF, UK
| | - Dina De Sousa
- The Wellcome Centre for Cell Biology, University of Edinburgh, Michael Swann Building, King’s Buildings, Max Born Crescent, Edinburgh, EH9 3BF, UK
| | - Ralph D. Hector
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Stuart R. Cobb
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Adrian Bird
- The Wellcome Centre for Cell Biology, University of Edinburgh, Michael Swann Building, King’s Buildings, Max Born Crescent, Edinburgh, EH9 3BF, UK
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Bahey NG, Gadalla KKE, McGonigal R, Bailey MES, Edgar JM, Cobb SR. Reduced axonal diameter of peripheral nerve fibers in a mouse model of Rett syndrome. Neuroscience 2017; 358:261-268. [PMID: 28687309 DOI: 10.1016/j.neuroscience.2017.06.061] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 06/27/2017] [Accepted: 06/28/2017] [Indexed: 12/29/2022]
Abstract
Rett syndrome (RTT) is a neurological disorder characterized by motor and cognitive impairment, autonomic dysfunction and a loss of purposeful hand skills. In the majority of cases, typical RTT is caused by de novo mutations in the X-linked gene, MECP2. Alterations in the structure and function of neurons within the central nervous system of RTT patients and Mecp2-null mouse models are well established. In contrast, few studies have investigated the effects of MeCP2-deficiency on peripheral nerves. In this study, we conducted detailed morphometric as well as functional analysis of the sciatic nerves of symptomatic adult female Mecp2+/- mice. We observed a significant reduction in the mean diameter of myelinated nerve fibers in Mecp2+/- mice. In myelinated fibers, mitochondrial densities per unit area of axoplasm were significantly altered in Mecp2+/- mice. However, conduction properties of the sciatic nerve of Mecp2 knockout mice were not different from control. These subtle changes in myelinated peripheral nerve fibers in heterozygous Mecp2 knockout mice could potentially explain some RTT phenotypes.
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Affiliation(s)
- Noha G Bahey
- Institute of Neuroscience and Psychology, University of Glasgow, United Kingdom; Histology Department, Faculty of Medicine, Tanta University, Egypt
| | - Kamal K E Gadalla
- Institute of Neuroscience and Psychology, University of Glasgow, United Kingdom; Pharmacology Department, Faculty of Medicine, Tanta University, Egypt
| | - Rhona McGonigal
- Institute of Infection, Immunity and Inflammation College of Medical, Veterinary and Life Sciences, University of Glasgow, United Kingdom
| | - Mark E S Bailey
- School of Life Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, United Kingdom
| | - Julia M Edgar
- Institute of Infection, Immunity and Inflammation College of Medical, Veterinary and Life Sciences, University of Glasgow, United Kingdom
| | - Stuart R Cobb
- Institute of Neuroscience and Psychology, University of Glasgow, United Kingdom.
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Trägårdh J, Robb G, Gadalla KKE, Cobb S, Travis C, Oppo GL, McConnell G. Label-free imaging of thick tissue at 1550 nm using a femtosecond optical parametric generator. Opt Lett 2015; 40:3484-7. [PMID: 26258338 DOI: 10.1364/ol.40.003484] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
We have developed a simple wavelength-tunable optical parametric generator (OPG), emitting broadband ultrashort pulses with peak wavelengths at 1530-1790 nm, for nonlinear label-free microscopy. The OPG consists of a periodically poled lithium niobate crystal, pumped at 1064 nm by a ultrafast Yb:fiber laser with high pulse energy. We demonstrate that this OPG can be used for label-free imaging, by third-harmonic generation, of nuclei of brain cells and blood vessels in a >150 μm thick brain tissue section, with very little decay of intensity with imaging depth and no visible damage to the tissue at an incident average power of 15 mW.
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Gadalla KKE, Ross PD, Riddell JS, Bailey MES, Cobb SR. Gait analysis in a Mecp2 knockout mouse model of Rett syndrome reveals early-onset and progressive motor deficits. PLoS One 2014; 9:e112889. [PMID: 25392929 PMCID: PMC4231076 DOI: 10.1371/journal.pone.0112889] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 10/16/2014] [Indexed: 11/19/2022] Open
Abstract
Rett syndrome (RTT) is a genetic disorder characterized by a range of features including cognitive impairment, gait abnormalities and a reduction in purposeful hand skills. Mice harbouring knockout mutations in the Mecp2 gene display many RTT-like characteristics and are central to efforts to find novel therapies for the disorder. As hand stereotypies and gait abnormalities constitute major diagnostic criteria in RTT, it is clear that motor and gait-related phenotypes will be of importance in assessing preclinical therapeutic outcomes. We therefore aimed to assess gait properties over the prodromal phase in a functional knockout mouse model of RTT. In male Mecp2 knockout mice, we observed alterations in stride, coordination and balance parameters at 4 weeks of age, before the onset of other overt phenotypic changes as revealed by observational scoring. These data suggest that gait measures may be used as a robust and early marker of MeCP2-dysfunction in future preclinical therapeutic studies.
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Affiliation(s)
- Kamal K. E. Gadalla
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
- Pharmacology Department, Faculty of Medicine, Tanta University, Egypt
| | - Paul D. Ross
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - John S. Riddell
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Mark E. S. Bailey
- School of Life Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Stuart R. Cobb
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
- * E-mail:
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Gadalla KKE, Bailey MES, Spike RC, Ross PD, Woodard KT, Kalburgi SN, Bachaboina L, Deng JV, West AE, Samulski RJ, Gray SJ, Cobb SR. Improved survival and reduced phenotypic severity following AAV9/MECP2 gene transfer to neonatal and juvenile male Mecp2 knockout mice. Mol Ther 2012; 21:18-30. [PMID: 23011033 DOI: 10.1038/mt.2012.200] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Typical Rett syndrome (RTT) is a pediatric disorder caused by loss-of-function mutations in the methyl-CpG binding protein 2 (MECP2) gene. The demonstrated reversibility of RTT-like phenotypes in mice suggests that MECP2 gene replacement is a potential therapeutic option in patients. We report improvements in survival and phenotypic severity in Mecp2-null male mice after neonatal intracranial delivery of a single-stranded (ss) AAV9/chicken β-actin (CBA)-MECP2 vector. Median survival was 16.6 weeks for MECP2-treated versus 9.3 weeks for green fluorescent protein (GFP)-treated mice. ssAAV9/CBA-MECP2-treated mice also showed significant improvement in the phenotype severity score, in locomotor function, and in exploratory activity, as well as a normalization of neuronal nuclear volume in transduced cells. Wild-type (WT) mice receiving neonatal injections of the same ssAAV9/CBA-MECP2 vector did not show any significant deficits, suggesting a tolerance for modest MeCP2 overexpression. To test a MECP2 gene replacement approach in a manner more relevant for human translation, a self-complementary (sc) adeno-associated virus (AAV) vector designed to drive MeCP2 expression from a fragment of the Mecp2 promoter was injected intravenously (IV) into juvenile (4-5 weeks old) Mecp2-null mice. While the brain transduction efficiency in juvenile mice was low (~2-4% of neurons), modest improvements in survival were still observed. These results support the concept of MECP2 gene therapy for RTT.
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Affiliation(s)
- Kamal K E Gadalla
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
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