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Mancini J, Dubus JC, Jouve E, Roux JC, Franco P, Lagrue E, Castelnau P, Cances C, Chaix Y, Rougeot-Jung C, Cornu C, Desportes V, Vallée L, Bahi-Buisson N, Truillet R, Attolini L, Villard L, Blin O, Micallef J. Effect of desipramine on patients with breathing disorders in RETT syndrome. Ann Clin Transl Neurol 2017; 5:118-127. [PMID: 29468173 PMCID: PMC5817841 DOI: 10.1002/acn3.468] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 08/21/2017] [Indexed: 12/27/2022] Open
Abstract
Objective Rett Syndrome (RTT) is a severe neurodevelopmental condition with breathing disorders, affecting around one in 10,000 female births. Desipramine, a noradrenaline reuptake inhibitor, reduced the number of apneas in Mecp2-deficient mice, a model of RTT. We planned a phase 2 trial to test its efficacy and its safety on breathing patterns in 36 girls with RTT. Methods The trial was a 6-month, multicenter, randomized, double-blind, placebo-controlled study registered with ClinicalTrials.gov, number NCT00990691. Girls diagnosed according to clinical examination and confirmed by genotyping were randomly assigned in a 1:1:1 ratio to receive 2-3 mg/kg Desipramine per day (high Desipramine), 1-2 mg/kg Desipramine per day (low Desipramine), or a placebo. The primary outcome was the change of apnea hypopnea index (AHI), defined by the number of apnea and hypopnea events per hour, assessed at 6 months from baseline. Intention-to-treat analysis was applied. Results The median change in AHI from baseline to 6 months was -31 (IQR: -37 to -11) for the high Desipramine, -17.5 (IQR: -31 to 13) for the low Desipramine, and -13 (IQR:-31 to 0) for the placebo group. We did not find any significant difference in these changes between the groups (P = 0.781). A significant inverse correlation between Desipramine plasma concentration and AHI (r = -0.44; P = 0.0002) was underlined. Interpretation This first clinical trial of desipramine did not show clinical efficacy. Although required further studies, the significant correlation between Desipramine concentrations and improvement of AHI provided additional and relevant reasons to test the noradrenergic pathway in RTT.
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Affiliation(s)
- Josette Mancini
- Neuropediatric Unit Aix Marseille University Children Hospital APHM, Timone, Neurosciences Institute Marseille France
| | - Jean-Christophe Dubus
- Pneumology Pediatric Unit Aix Marseille University Children Hospital CNRS URMITE 6236A PHM Marseille France
| | - Elisabeth Jouve
- Department of Pharmacology F-CRIN Orphan DEV Timone Neurosciences Institute Aix Marseille University CNRS INTAPHM, CIC CPCET CHU Timone Marseille France
| | | | - Patricia Franco
- Neuropediatric Ward Hypnology Unit Lyon University Civil Hospices of Lyon INSERM U628 Lyon France
| | - Emmanuelle Lagrue
- Neuropediatrics and Handicap Department Tours University INSERM, UMR U930 Imaging and Brain, CHRU Tours Tours France
| | - Pierre Castelnau
- Neuropediatrics and Handicap Department Tours University INSERM, UMR U930 Imaging and Brain, CHRU Tours Tours France
| | - Claude Cances
- Neuropediatric Unit Neuro Imaging Center Toulouse University Children Hospital CHU PURPANUMR 1214 Toulouse France
| | - Yves Chaix
- Neuropediatric Unit Neuro Imaging Center Toulouse University Children Hospital CHU PURPANUMR 1214 Toulouse France
| | - Christelle Rougeot-Jung
- Lyon University National Reference Center for Rare Diseases with Intellectual Disability HFME Hospices Civils de Lyon Lyon France.,CNRS UMR 5304 ISC Lyon France
| | - Catherine Cornu
- Department of Pharmacotoxicology Clinical Investigation Center Hospices Civils de Lyon INSERM 1407 Lyon France.,Lyon University CNRS UMR 5558 Lyon France
| | - Vincent Desportes
- Lyon University National Reference Center for Rare Diseases with Intellectual Disability HFME Hospices Civils de Lyon Lyon France.,CNRS UMR 5304 ISC Lyon France
| | - Louis Vallée
- Department of Neuropediatrics Lille North 2 University CHRU Hôpital Roger Salengro Lille France
| | - Nadia Bahi-Buisson
- Imagine Institute and INSERM UMR-1163 Embryology and Genetics of Congenital Malformations Pediatric Neurology Paris Descartes - Sorbonne Paris Cité University Necker Enfants Malades University Hospital AP-HP Paris France
| | - Romain Truillet
- Department of Pharmacology F-CRIN Orphan DEV Timone Neurosciences Institute Aix Marseille University CNRS INTAPHM, CIC CPCET CHU Timone Marseille France
| | - Laurence Attolini
- Department of Pharmacology F-CRIN Orphan DEV Timone Neurosciences Institute Aix Marseille University CNRS INTAPHM, CIC CPCET CHU Timone Marseille France
| | - Laurent Villard
- Aix Marseille University INSERM, GMGF UMR_S 910 Marseille France
| | - Olivier Blin
- Department of Pharmacology F-CRIN Orphan DEV Timone Neurosciences Institute Aix Marseille University CNRS INTAPHM, CIC CPCET CHU Timone Marseille France
| | - Joëlle Micallef
- Department of Pharmacology F-CRIN Orphan DEV Timone Neurosciences Institute Aix Marseille University CNRS INTAPHM, CIC CPCET CHU Timone Marseille France
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52
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Lee BH, Reijnders MRF, Abubakare O, Tuttle E, Lape B, Minks KQ, Stodgell C, Bennetto L, Kwon J, Fong CT, Gripp KW, Marsh ED, Smith WE, Huq AM, Coury SA, Tan WH, Solis O, Mehta RI, Leventer RJ, Baralle D, Hunt D, Paciorkowski AR. Expanding the neurodevelopmental phenotype of PURA syndrome. Am J Med Genet A 2017; 176:56-67. [PMID: 29150892 DOI: 10.1002/ajmg.a.38521] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 10/04/2017] [Accepted: 10/08/2017] [Indexed: 01/07/2023]
Abstract
PURA syndrome is a recently described developmental encephalopathy presenting with neonatal hypotonia, feeding difficulties, global developmental delay, severe intellectual disability, and frequent apnea and epilepsy. We describe 18 new individuals with heterozygous sequence variations in PURA. A neuromotor disorder starting with neonatal hyptonia, but ultimately allowing delayed progression to walking, was present in nearly all individuals. Congenital apnea was present in 56% during infancy, but all cases in this cohort resolved during the first year of life. Feeding difficulties were frequently reported, with gastrostomy tube placement required in 28%. Epilepsy was present in 50% of the subjects, including infantile spasms and Lennox-Gastaut syndrome. Skeletal complications were found in 39%. Disorders of gastrointestinal motility and nystagmus were also recurrent features. Autism was diagnosed in one individual, potentially expanding the neurodevelopmental phenotype associated with this syndrome. However, we did not find additional PURA sequence variations in a cohort of 120 subjects with autism. We also present the first neuropathologic studies of PURA syndrome, and describe chronic inflammatory changes around the arterioles within the deep white matter. We did not find significant correlations between mutational class and severity, nor between location of the sequence variation in PUR repeat domains. Further studies are required in larger cohorts of subjects with PURA syndrome to clarify these genotype-phenotype associations.
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Affiliation(s)
- Bo Hoon Lee
- Department of Neurology, University of Rochester Medical Center, Rochester, New York
| | - Margot R F Reijnders
- Department of Human Genetics, Donders Institute for Brain, Cognition, and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Oluwatobi Abubakare
- Center for Neural Development and Disease, University of Rochester Medical Center, Rochester, New York
| | - Emily Tuttle
- Center for Neural Development and Disease, University of Rochester Medical Center, Rochester, New York
| | - Brynn Lape
- Center for Neural Development and Disease, University of Rochester Medical Center, Rochester, New York
| | - Kelly Q Minks
- Department of Neurology, University of Rochester Medical Center, Rochester, New York
| | - Christopher Stodgell
- Department of Obstetrics and Gynecology, University of Rochester Medical Center, Rochester, New York
| | - Loisa Bennetto
- Department of Clinical and Social Sciences in Psychology, University of Rochester, Rochester, New York
| | - Jennifer Kwon
- Department of Neurology, University of Rochester Medical Center, Rochester, New York.,Department of Pediatrics, University of Rochester Medical Center, Rochester, New York.,Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, Rochester, New York
| | - Chin-To Fong
- Department of Pediatrics, University of Rochester Medical Center, Rochester, New York
| | - Karen W Gripp
- A.I. du Pont Hospital for Children/Nemours, Wilmington, Delaware
| | - Eric D Marsh
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, and Pediatric Regional Epilepsy Program, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Wendy E Smith
- Department of Pediatrics, Maine Medical Center, Portland, Maine
| | - Ahm M Huq
- Departments of Pediatrics and Neurology, Wayne State University, Children's Hospital of Michigan, Detroit, Michigan
| | - Stephanie A Coury
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, Massachusetts
| | - Wen-Hann Tan
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, Massachusetts
| | - Orestes Solis
- Center for Neural Development and Disease, University of Rochester Medical Center, Rochester, New York
| | - Rupal I Mehta
- Center for Neural Development and Disease, University of Rochester Medical Center, Rochester, New York.,Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, Rochester, New York
| | - Richard J Leventer
- The Royal Children's Hospital Department of Neurology, University of Melbourne, Department of Pediatrics and the Murdoch Children's Hospital Institute, Melbourne, Victoria, Australia
| | - Diana Baralle
- Human Development and Health, Faculty of Medicine, University of Southampton, Southampton, Hampshire, UK.,Faculty of Medicine, Wessex Clinical Genetics Service, Princess Anne Hospital, University of Southampton, Southampton, Hampshire, UK
| | - David Hunt
- Faculty of Medicine, Wessex Clinical Genetics Service, Princess Anne Hospital, University of Southampton, Southampton, Hampshire, UK
| | - Alex R Paciorkowski
- Department of Neurology, University of Rochester Medical Center, Rochester, New York.,Center for Neural Development and Disease, University of Rochester Medical Center, Rochester, New York.,Department of Pediatrics, University of Rochester Medical Center, Rochester, New York.,Departments of Neuroscience and Biomedical Genetics, University of Rochester Medical Center, Rochester, New York
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53
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Howell CJ, Sceniak MP, Lang M, Krakowiecki W, Abouelsoud FE, Lad SU, Yu H, Katz DM. Activation of the Medial Prefrontal Cortex Reverses Cognitive and Respiratory Symptoms in a Mouse Model of Rett Syndrome. eNeuro 2017; 4:ENEURO.0277-17.2017. [PMID: 29333487 PMCID: PMC5762598 DOI: 10.1523/eneuro.0277-17.2017] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 11/27/2017] [Accepted: 12/01/2017] [Indexed: 12/30/2022] Open
Abstract
Rett syndrome (RTT) is a severe neurodevelopmental disorder caused by loss-of-function mutations in the gene encoding methyl-CpG-binding protein 2 (MeCP2; Amir et al., 1999), a transcriptional regulatory protein (Klose et al., 2005). Mouse models of RTT (Mecp2 mutants) exhibit excitatory hypoconnectivity in the medial prefrontal cortex (mPFC; Sceniak et al., 2015), a region critical for functions that are abnormal in RTT patients, ranging from learning and memory to regulation of visceral homeostasis (Riga et al., 2014). The present study was designed to test the hypothesis that increasing the activity of mPFC pyramidal neurons in heterozygous female Mecp2 mutants (Hets) would ameliorate RTT-like symptoms, including deficits in respiratory control and long-term retrieval of auditory conditioned fear. Selective activation of mPFC pyramidal neurons in adult animals was achieved by bilateral infection with an AAV8 vector expressing excitatory hm3D(Gq) DREADD (Designer Receptors Exclusively Activated by Designer Drugs) (Armbruster et al., 2007) under the control of the CamKIIa promoter. DREADD activation in Mecp2 Hets completely restored long-term retrieval of auditory conditioned fear, eliminated respiratory apneas, and reduced respiratory frequency variability to wild-type (Wt) levels. Reversal of respiratory symptoms following mPFC activation was associated with normalization of Fos protein levels, a marker of neuronal activity, in a subset of brainstem respiratory neurons. Thus, despite reduced levels of MeCP2 and severe neurological deficits, mPFC circuits in Het mice are sufficiently intact to generate normal behavioral output when pyramidal cell activity is increased. These findings highlight the contribution of mPFC hypofunction to the pathophysiology of RTT and raise the possibility that selective activation of cortical regions such as the mPFC could provide therapeutic benefit to RTT patients.
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Affiliation(s)
- C James Howell
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106
| | - Michael P Sceniak
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106
| | - Min Lang
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106
| | - Wenceslas Krakowiecki
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106
| | - Fatimah E Abouelsoud
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106
| | - Saloni U Lad
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106
| | - Heping Yu
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106
| | - David M Katz
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106
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54
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Pathogenesis of Lethal Aspiration Pneumonia in Mecp2-null Mouse Model for Rett Syndrome. Sci Rep 2017; 7:12032. [PMID: 28931890 PMCID: PMC5607245 DOI: 10.1038/s41598-017-12293-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 09/06/2017] [Indexed: 11/09/2022] Open
Abstract
Rett syndrome (RTT) is a neurodevelopmental disorder mainly caused by mutations in the gene encoding the transcriptional regulator Methyl-CpG-binding protein 2 (MeCP2), located on the X chromosome. Many RTT patients have breathing abnormalities, such as apnea and breathing irregularity, and respiratory infection is the most common cause of death in these individuals. Previous studies showed that MeCP2 is highly expressed in the lung, but its role in pulmonary function remains unknown. In this study, we found that MeCP2 deficiency affects pulmonary gene expression and structures. We also found that Mecp2-null mice, which also have breathing problems, often exhibit inflammatory lung injury. These injuries occurred in specific sites in the lung lobes. In addition, polarizable foreign materials were identified in the injured lungs of Mecp2-null mice. These results indicated that aspiration might be a cause of inflammatory lung injury in Mecp2-null mice. On the other hand, MeCP2 deficiency affected the expression of several neuromodulator genes in the lower brainstem. Among them, neuropeptide substance P (SP) immunostaining was reduced in Mecp2-null brainstem. These findings suggest that alteration of SP expression in brainstem may be involved in autonomic dysregulation, and may be one of the causes of aspiration in Mecp2-null mice.
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55
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Na ES, De Jesús-Cortés H, Martinez-Rivera A, Kabir ZD, Wang J, Ramesh V, Onder Y, Rajadhyaksha AM, Monteggia LM, Pieper AA. D-cycloserine improves synaptic transmission in an animal model of Rett syndrome. PLoS One 2017; 12:e0183026. [PMID: 28813484 PMCID: PMC5559075 DOI: 10.1371/journal.pone.0183026] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 07/30/2017] [Indexed: 01/24/2023] Open
Abstract
Rett syndrome (RTT), a leading cause of intellectual disability in girls, is predominantly caused by mutations in the X-linked gene MECP2. Disruption of Mecp2 in mice recapitulates major features of RTT, including neurobehavioral abnormalities, which can be reversed by re-expression of normal Mecp2. Thus, there is reason to believe that RTT could be amenable to therapeutic intervention throughout the lifespan of patients after the onset of symptoms. A common feature underlying neuropsychiatric disorders, including RTT, is altered synaptic function in the brain. Here, we show that Mecp2tm1.1Jae/y mice display lower presynaptic function as assessed by paired pulse ratio, as well as decreased long term potentiation (LTP) at hippocampal Schaffer–collateral-CA1 synapses. Treatment of Mecp2tm1.1Jae/y mice with D-cycloserine (DCS), an FDA-approved analog of the amino acid D-alanine with antibiotic and glycinergic activity, corrected the presynaptic but not LTP deficit without affecting deficient hippocampal BDNF levels. DCS treatment did, however, partially restore lower BDNF levels in the brain stem and striatum. Thus, treatment with DCS may mitigate the severity of some of the neurobehavioral symptoms experienced by patients with Rett syndrome.
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Affiliation(s)
- Elisa S. Na
- Department of Psychology & Philosophy, Texas Woman’s University, Denton, TX, United States of America
| | - Héctor De Jesús-Cortés
- Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA, United States of America
| | - Arlene Martinez-Rivera
- Division of Pediatric Neurology, Department of Pediatrics, Weill Cornell Medicine, Cornell University, New York, NY, United States of America
- Weill Cornell Autism Research Program, Weill Cornell Medicine, Cornell University, New York, NY, United States of America
| | - Zeeba D. Kabir
- Division of Pediatric Neurology, Department of Pediatrics, Weill Cornell Medicine, Cornell University, New York, NY, United States of America
- Weill Cornell Autism Research Program, Weill Cornell Medicine, Cornell University, New York, NY, United States of America
| | - Jieqi Wang
- Department of Psychiatry, University of Iowa Carver College of Medicine, Iowa City, IA, United States of America
| | - Vijayashree Ramesh
- Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX, United States of America
| | - Yasemin Onder
- Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX, United States of America
| | - Anjali M. Rajadhyaksha
- Division of Pediatric Neurology, Department of Pediatrics, Weill Cornell Medicine, Cornell University, New York, NY, United States of America
- Weill Cornell Autism Research Program, Weill Cornell Medicine, Cornell University, New York, NY, United States of America
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, Cornell University, New York, NY, United States of America
- * E-mail: (AMR); (LMM); (AAP)
| | - Lisa M. Monteggia
- Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX, United States of America
- * E-mail: (AMR); (LMM); (AAP)
| | - Andrew A. Pieper
- Weill Cornell Autism Research Program, Weill Cornell Medicine, Cornell University, New York, NY, United States of America
- Department of Psychiatry, University of Iowa Carver College of Medicine, Iowa City, IA, United States of America
- Department of Neurology, University of Iowa Carver College of Medicine, Iowa City, IA, United States of America
- Department of Free Radical and Radiation Biology, University of Iowa Carver College of Medicine, Iowa City, IA, United States of America
- Department of Veterans Affairs, University of Iowa Carver College of Medicine, Iowa City, IA, United States of America
- Pappajohn Biomedical Institute, University of Iowa Carver College of Medicine, Iowa City, IA, United States of America
- * E-mail: (AMR); (LMM); (AAP)
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56
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Ludwig AK, Zhang P, Hastert FD, Meyer S, Rausch C, Herce HD, Müller U, Lehmkuhl A, Hellmann I, Trummer C, Storm C, Leonhardt H, Cardoso MC. Binding of MBD proteins to DNA blocks Tet1 function thereby modulating transcriptional noise. Nucleic Acids Res 2017; 45:2438-2457. [PMID: 27923996 PMCID: PMC5389475 DOI: 10.1093/nar/gkw1197] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 11/20/2016] [Indexed: 12/18/2022] Open
Abstract
Aberrant DNA methylation is a hallmark of various human disorders, indicating that the spatial and temporal regulation of methylation readers and modifiers is imperative for development and differentiation. In particular, the cross-regulation between 5-methylcytosine binders (MBD) and modifiers (Tet) has not been investigated. Here, we show that binding of Mecp2 and Mbd2 to DNA protects 5-methylcytosine from Tet1-mediated oxidation. The mechanism is not based on competition for 5-methylcytosine binding but on Mecp2 and Mbd2 directly restricting Tet1 access to DNA. We demonstrate that the efficiency of this process depends on the number of bound MBDs per DNA molecule. Accordingly, we find 5-hydroxymethylcytosine enriched at heterochromatin of Mecp2-deficient neurons of a mouse model for Rett syndrome and Tet1-induced reexpression of silenced major satellite repeats. These data unveil fundamental regulatory mechanisms of Tet enzymes and their potential pathophysiological role in Rett syndrome. Importantly, it suggests that Mecp2 and Mbd2 have an essential physiological role as guardians of the epigenome.
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Affiliation(s)
- Anne K Ludwig
- Cell Biology and Epigenetics, Department of Biology, Technische Universität Darmstadt, 64287 Darmstadt, Germany
| | - Peng Zhang
- Cell Biology and Epigenetics, Department of Biology, Technische Universität Darmstadt, 64287 Darmstadt, Germany
| | - Florian D Hastert
- Cell Biology and Epigenetics, Department of Biology, Technische Universität Darmstadt, 64287 Darmstadt, Germany
| | - Stephanie Meyer
- Cell Biology and Epigenetics, Department of Biology, Technische Universität Darmstadt, 64287 Darmstadt, Germany
| | - Cathia Rausch
- Cell Biology and Epigenetics, Department of Biology, Technische Universität Darmstadt, 64287 Darmstadt, Germany
| | - Henry D Herce
- Cell Biology and Epigenetics, Department of Biology, Technische Universität Darmstadt, 64287 Darmstadt, Germany
| | - Udo Müller
- Human Biology and BioImaging, Department of Biology II, LMU Munich, 82152 Martinsried, Germany
| | - Anne Lehmkuhl
- Cell Biology and Epigenetics, Department of Biology, Technische Universität Darmstadt, 64287 Darmstadt, Germany
| | - Ines Hellmann
- Anthropology and Human Genomics, Department Biology II, LMU Munich, 82152 Martinsried, Germany
| | - Carina Trummer
- Human Biology and BioImaging, Department of Biology II, LMU Munich, 82152 Martinsried, Germany
| | - Christian Storm
- Chemical Plant Ecology, Department of Biology, Technische Universität Darmstadt, 64287 Darmstadt, Germany
| | - Heinrich Leonhardt
- Human Biology and BioImaging, Department of Biology II, LMU Munich, 82152 Martinsried, Germany
| | - M Cristina Cardoso
- Cell Biology and Epigenetics, Department of Biology, Technische Universität Darmstadt, 64287 Darmstadt, Germany
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Drotlef DM, Amjadi M, Yunusa M, Sitti M. Bioinspired Composite Microfibers for Skin Adhesion and Signal Amplification of Wearable Sensors. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1701353. [PMID: 28523760 DOI: 10.1002/adma.201701353] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 03/31/2017] [Indexed: 05/26/2023]
Abstract
A facile approach is proposed for superior conformation and adhesion of wearable sensors to dry and wet skin. Bioinspired skin-adhesive films are composed of elastomeric microfibers decorated with conformal and mushroom-shaped vinylsiloxane tips. Strong skin adhesion is achieved by crosslinking the viscous vinylsiloxane tips directly on the skin surface. Furthermore, composite microfibrillar adhesive films possess a high adhesion strength of 18 kPa due to the excellent shape adaptation of the vinylsiloxane tips to the multiscale roughness of the skin. As a utility of the skin-adhesive films in wearable-device applications, they are integrated with wearable strain sensors for respiratory and heart-rate monitoring. The signal-to-noise ratio of the strain sensor is significantly improved to 59.7 because of the considerable signal amplification of microfibrillar skin-adhesive films.
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Affiliation(s)
- Dirk-M Drotlef
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, Stuttgart, 70569, Germany
| | - Morteza Amjadi
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, Stuttgart, 70569, Germany
- Max Planck-ETH Center for Learning Systems, Max Planck Institute for Intelligent Systems, Stuttgart, 70569, Germany
| | - Muhammad Yunusa
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, Stuttgart, 70569, Germany
| | - Metin Sitti
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, Stuttgart, 70569, Germany
- Max Planck-ETH Center for Learning Systems, Max Planck Institute for Intelligent Systems, Stuttgart, 70569, Germany
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58
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Progressive Changes in a Distributed Neural Circuit Underlie Breathing Abnormalities in Mice Lacking MeCP2. J Neurosci 2017; 36:5572-86. [PMID: 27194336 DOI: 10.1523/jneurosci.2330-15.2016] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 04/13/2016] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Rett syndrome (RTT) is a neurodevelopmental disorder caused by mutations in Methyl-CpG-binding protein 2 (MECP2). Severe breathing abnormalities are common in RTT and are reproduced in mouse models of RTT. Previously, we found that removing MeCP2 from the brainstem and spinal cord in mice caused early lethality and abnormal breathing. To determine whether loss of MeCP2 in functional components of the respiratory network causes specific breathing disorders, we used the Cre/LoxP system to differentially manipulate MeCP2 expression throughout the brainstem respiratory network, specifically within HoxA4-derived tissues, which include breathing control circuitry within the nucleus tractus solitarius and the caudal part of ventral respiratory column but do not include more rostral parts of the breathing control circuitry. To determine whether respiratory phenotypes manifested in animals with MeCP2 removed from specific pons medullary respiratory circuits, we performed whole-body plethysmography and electrophysiological recordings from in vitro brainstem slices from mice lacking MeCP2 in different circuits. Our results indicate that MeCP2 expression in the medullary respiratory network is sufficient for normal respiratory rhythm and preventing apnea. However, MeCP2 expression within components of the breathing circuitry rostral to the HoxA4 domain are neither sufficient to prevent the hyperventilation nor abnormal hypoxic ventilatory response. Surprisingly, we found that MeCP2 expression in the HoxA4 domain alone is critical for survival. Our study reveals that MeCP2 is differentially required in select respiratory components for different aspects of respiratory functions, and collectively for the integrity of this network functions to maintain proper respiration. SIGNIFICANCE STATEMENT Breathing abnormalities are a significant clinical feature in Rett syndrome and are robustly reproduced in the mouse models of this disease. Previous work has established that alterations in the function of MeCP2, the protein encoded by the gene mutated in Rett syndrome, within the hindbrain are critical for control of normal breathing. Here we show that MeCP2 function plays distinct roles in specific brainstem regions in the genesis of various aspects of abnormal breathing. This provides insight into the pathogenesis of these breathing abnormalities in Rett syndrome, which could be used to target treatments to improve these symptoms. Furthermore, it provides further knowledge about the fundamental neural circuits that control breathing.
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59
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Mackay J, Downs J, Wong K, Heyworth J, Epstein A, Leonard H. Autonomic breathing abnormalities in Rett syndrome: caregiver perspectives in an international database study. J Neurodev Disord 2017; 9:15. [PMID: 28465761 PMCID: PMC5410057 DOI: 10.1186/s11689-017-9196-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2016] [Accepted: 04/21/2017] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Rett syndrome is a severe neurodevelopmental disorder associated with mutations in the MECP2 gene. Irregular breathing patterns and abdominal bloating are prominent but poorly understood features. Our aims were to characterize the abnormal breathing patterns and abdominal bloating, investigate the distribution of these by age and mutation type and examine their impact and management from a caregiver perspective. METHODS We invited previously recruited families from the International Rett Syndrome Study to complete a web-based questionnaire concerning their family member with Rett syndrome aged between 2 and 57 years. We used logistic regression to investigate presence, frequency and impact of breath-holding, hyperventilation, or abdominal bloating by age group and mutation type. Age of onset for both breathing abnormalities was investigated using time-to-onset analysis, and the Kaplan-Meier method was used to estimate the failure function for the study sample. Descriptive statistics were used to characterize the management of irregular breathing. RESULTS Questionnaires were returned by 413/482 (85.7%) families. Breath-holding was reported for 68.8%, hyperventilation for 46.4% and abdominal bloating for 42.4%. Hyperventilation was more prevalent and frequent in those younger than 7 years of age and abdominal bloating in those aged over 20 years. Onset of breathing irregularities usually occurred during early childhood. Caregivers perceived that daily life was considerably impacted for almost half (44.1%) of those with abdominal bloating and in just over than a third of those with breath-holding (35.8%) or hyperventilation (35.1%). Although perceived impact was broadly comparable between age and mutation groups for breath-holding, hyperventilation and abdominal bloating, girls and women with a p.Arg294* mutation were considered to be more affected by all three conditions. Only 31 individuals had received medically prescribed treatments including 12 different medications, added oxygen, rebreathing apparatus or non-invasive ventilation. CONCLUSIONS Autonomic disturbances are prevalent and burdensome in Rett syndrome. This information may guide the design of inclusion criteria and outcome measures for clinical intervention trials targeting autonomic abnormalities. Further investigation of available treatments is necessary to delineate evidence-based management pathways.
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Affiliation(s)
- Jessica Mackay
- Telethon Kids Institute, The University of Western Australia, PO Box 855, West Perth, WA 6872 Australia
- School of Population Health, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 Australia
| | - Jenny Downs
- Telethon Kids Institute, The University of Western Australia, PO Box 855, West Perth, WA 6872 Australia
- School of Physiotherapy and Exercise Science, Curtin University, GPO Box U1987, Perth, WA 6845 Australia
| | - Kingsley Wong
- Telethon Kids Institute, The University of Western Australia, PO Box 855, West Perth, WA 6872 Australia
| | - Jane Heyworth
- School of Population Health, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 Australia
| | - Amy Epstein
- Telethon Kids Institute, The University of Western Australia, PO Box 855, West Perth, WA 6872 Australia
| | - Helen Leonard
- Telethon Kids Institute, The University of Western Australia, PO Box 855, West Perth, WA 6872 Australia
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Ciaccio C, Di Pierro D, Sbardella D, Tundo GR, Curatolo P, Galasso C, Santarone ME, Casasco M, Cozza P, Cortelazzo A, Rossi M, De Felice C, Hayek J, Coletta M, Marini S. Oxygen exchange and energy metabolism in erythrocytes of Rett syndrome and their relationships with respiratory alterations. Mol Cell Biochem 2017; 426:205-213. [PMID: 28063007 DOI: 10.1007/s11010-016-2893-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Accepted: 12/02/2016] [Indexed: 10/20/2022]
Abstract
Rett syndrome (RTT) is a neurodevelopmental disorder, mainly affecting females, which is associated to a mutation on the methyl-CpG-binding protein 2 gene. In the pathogenesis and progression of classic RTT, red blood cell (RBC) morphology has been shown to be an important biosensor for redox imbalance and chronic hypoxemia. Here we have evaluated the impact of oxidation and redox imbalance on several functional properties of RTT erythrocytes. In particular, we report for the first time a stopped-flow measurement of the kinetics of oxygen release by RBCs and the analysis of the intrinsic affinity of the hemoglobin (Hb). According to our experimental approach, RBCs from RTT patients do not show any intrinsic difference with respect to those from healthy controls neither in Hb's oxygen-binding affinity nor in O2 exchange processes at 37 °C. Therefore, these factors do not contribute to the observed alteration of the respiratory function in RTT patients. Moreover, the energy metabolism of RBCs, from both RTT patients and controls, was evaluated by ion-pairing HPLC method and related to the level of malondialdehyde and to the oxidative radical scavenging capacity of red cells. Results have clearly confirmed significant alterations in antioxidant defense capability, adding important informations concerning the high-energy compound levels in RBCs of RTT subjects, underlying possible correlations with inflammatory tissue alterations.
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Affiliation(s)
- Chiara Ciaccio
- Department of Clinical Sciences and Translational Medicine, University of Roma Tor Vergata, Via Montpellier 1, 00133, Rome, Italy.
| | - Donato Di Pierro
- Department of Clinical Sciences and Translational Medicine, University of Roma Tor Vergata, Via Montpellier 1, 00133, Rome, Italy
| | - Diego Sbardella
- Department of Clinical Sciences and Translational Medicine, University of Roma Tor Vergata, Via Montpellier 1, 00133, Rome, Italy
| | - Grazia Raffaella Tundo
- Department of Clinical Sciences and Translational Medicine, University of Roma Tor Vergata, Via Montpellier 1, 00133, Rome, Italy
| | - Paolo Curatolo
- Department of Systems Medicine, University Hospital of Rome Tor Vergata, Rome, Italy
| | - Cinzia Galasso
- Department of Systems Medicine, University Hospital of Rome Tor Vergata, Rome, Italy
| | - Marta Elena Santarone
- Department of Systems Medicine, University Hospital of Rome Tor Vergata, Rome, Italy
| | | | - Paola Cozza
- Department of Clinical Sciences and Translational Medicine, University of Roma Tor Vergata, Via Montpellier 1, 00133, Rome, Italy
| | - Alessio Cortelazzo
- Department of Medical Biotechnologies, University of Siena, Siena, Italy
| | - Marcello Rossi
- Respiratory Pathophysiology and Rehabilitation Unit, University Hospital, AOUS, Siena, Italy
| | - Claudio De Felice
- Neonatal Intensive Care Unit, University Hospital, AOUS, Siena, Italy
| | - Joussef Hayek
- Child Neuropsychiatry Unit, University Hospital, AOUS, Siena, Italy
| | - Massimo Coletta
- Department of Clinical Sciences and Translational Medicine, University of Roma Tor Vergata, Via Montpellier 1, 00133, Rome, Italy
| | - Stefano Marini
- Department of Clinical Sciences and Translational Medicine, University of Roma Tor Vergata, Via Montpellier 1, 00133, Rome, Italy
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Effects of chronic exposure to low dose THIP on brainstem neuronal excitability in mouse models of Rett syndrome: Evidence from symptomatic females. Neuropharmacology 2017; 116:288-299. [PMID: 28069353 DOI: 10.1016/j.neuropharm.2017.01.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2016] [Revised: 12/10/2016] [Accepted: 01/04/2017] [Indexed: 01/17/2023]
Abstract
Rett Syndrome (RTT) is a neurodevelopmental disorder caused by mutations of the MECP2 gene, affecting predominantly females. One of the characteristic features of the disease is defective brainstem autonomic function. In Mecp2-/Y mice, several groups of brainstem neurons are overly excitable, which causes destabilization of neuronal networks for the autonomic control. We have previously shown that the extrasynaptic GABAA receptor agonist THIP relieves many RTT-like symptoms in Mecp2-/Y mice. Although neuronal activity is inhibited by acute THIP exposure, how a chronic treatment affects neuronal excitability remains elusive. Thus, we performed studies to address whether increased excitability occurs in brainstem neurons of female Mecp2+/- mice, how the MeCP expression affects the neuronal excitability, and whether chronic THIP exposure improves the neuronal hyperexcitability. Symptomatic Mecp2+/- (sMecp2+/-) female mice were identified with a two-step screening system. Whole-cell recording was performed in brain slices after a prior exposure of the sMecp2+/- mice to a 5-week low-dose THIP. Neurons in the locus coeruleus (LC) and the mesencephalic trigeminal nucleus (Me5) showed excessive firing activity in the sMecp2+/- mice. THIP pretreatment reduced the hyperexcitability of both LC and Me5 neurons in the sMecp2+/- mice, to a similar level as their counterparts in Mecp2-/Y mice. In identified LC neurons, the hyperexcitability appeared to be determined by not only the MeCP2 expression, but also their environmental cues. The alleviation of LC neuronal hyperexcitability seems to benefit brainstem autonomic function as THIP also improved breathing abnormalities of these sMecp2+/- mice.
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The Role of Noncoding RNAs in Neurodevelopmental Disorders: The Case of Rett Syndrome. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 978:23-37. [DOI: 10.1007/978-3-319-53889-1_2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Neurodevelopmental Effects of Serotonin on the Brainstem Respiratory Network. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1015:193-216. [DOI: 10.1007/978-3-319-62817-2_11] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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Dziwota E, Fałkowska U, Adamczyk K, Adamczyk D, Stefańska A, Pawęzka J, Olajossy M. Silent angels the genetic and clinical aspects of Rett syndrome. CURRENT PROBLEMS OF PSYCHIATRY 2016. [DOI: 10.1515/cpp-2016-0028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abstract
Rett syndrome is a neurodevelopmental genetic disorder and, because of some behavioral characteristics, individuals affected by the disease are known as silent angels. Girls with Rett syndrome perform stereotyped movements, they have learning difficulties, their reaction time is prolonged, and they seem alienated in the environment. These children require constant pediatric, neurological and orthopedic care. In the treatment of Rett syndrome physical therapy, music therapy, hydrotherapy, hippotherapy, behavioral methods, speech therapy and diet, are also used. In turn, psychological therapy of the syndrome is based on the sensory integration method, using two or more senses simultaneously. In 80% of cases, the syndrome is related to mutations of the MECP2 gene, located on chromosome X. The pathogenesis of Rett syndrome is caused by the occurrence of a non-functional MeCP2 protein, which is a transcription factor of many genes, i.e. Bdnf, mef2c, Sgk1, Uqcrc1. Abnormal expression of these genes reveals a characteristic disease phenotype. Clinical symptoms relate mainly to the nervous, respiratory, skeletal and gastrointestinal systems. Currently causal treatment is not possible. However, researchers are developing methods by which, perhaps in the near future, it will be possible to eliminate the mutations in the MECP2 gene, and this will give a chance to the patient for normal functioning.
The paper presents the etiology and pathogenesis of the disease, genetic, clinical, pharmacological aspects and other forms of Rett syndrome treatment.
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Affiliation(s)
- Ewelina Dziwota
- Second Department of Psychiatry and Psychiatric Rehabilitation, Department of Psychiatry at the Medical University of Lublin
| | - Urszula Fałkowska
- Students Scientific Society at the Second Department of Psychiatry and Psychiatric Rehabilitation
| | - Katarzyna Adamczyk
- Students Scientific Society at the Second Department of Psychiatry and Psychiatric Rehabilitation
| | - Dorota Adamczyk
- Students Scientific Society at the Second Department of Psychiatry and Psychiatric Rehabilitation
| | - Alena Stefańska
- Department of Clinical Psychology and Cardiology, Medical University, Lublin
| | - Justyna Pawęzka
- Second Department of Psychiatry and Psychiatric Rehabilitation, Department of Psychiatry at the Medical University of Lublin
| | - Marcin Olajossy
- Second Department of Psychiatry and Psychiatric Rehabilitation, Department of Psychiatry at the Medical University of Lublin
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Ma M, Adams HR, Seltzer LE, Dobyns WB, Paciorkowski AR. Phenotype Differentiation of FOXG1 and MECP2 Disorders: A New Method for Characterization of Developmental Encephalopathies. J Pediatr 2016; 178:233-240.e10. [PMID: 27640358 PMCID: PMC5873956 DOI: 10.1016/j.jpeds.2016.08.032] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 06/14/2016] [Accepted: 08/09/2016] [Indexed: 01/07/2023]
Abstract
OBJECTIVE To differentiate developmental encephalopathies by creating a novel quantitative phenotyping tool. STUDY DESIGN We created the Developmental Encephalopathy Inventory (DEI) to differentiate disorders with complex multisystem neurodevelopmental symptoms. We then used the DEI to study the phenotype features of 20 subjects with FOXG1 disorder and 11 subjects with MECP2 disorder. RESULTS The DEI identified core domains of fine motor and expressive language that were severely impaired in both disorders. Individuals with FOXG1 disorder were overall more severely impaired. Subjects with FOXG1 disorder were less able to walk, had worse fine motor skills, more disability in receptive language and reciprocity, and had more disordered sleep than did subjects with MECP2 disorder (P <.05). Covariance, cluster, and principal component analysis confirmed a relationship between impaired awareness, reciprocity, and language in both disorders. In addition, abnormal ambulation was a first principal component for FOXG1 but not for MECP2 disorder, suggesting that impaired ambulation is a strong differentiating factor clinically between the 2 disorders. CONCLUSIONS We have developed a novel quantitative developmental assessment tool for developmental encephalopathies and propose this tool as a method to identify and illustrate core common and differential domains of disability in these complex disorders. These findings demonstrate clear phenotype differences between FOXG1 and MECP2 disorders.
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Affiliation(s)
- Mandy Ma
- University of Buffalo School of Medicine, Buffalo, NY
| | - Heather R. Adams
- Department of Neurology, University of Rochester Medical Center, Rochester, NY
| | - Laurie E. Seltzer
- Department of Neurology, University of Rochester Medical Center, Rochester, NY,Strong Epilepsy Center, University of Rochester Medical Center, Rochester, NY
| | - William B. Dobyns
- Department of Neurology, University of Washington, Seattle, WA,Division of Medical Genetics, Department of Pediatrics, University of Washington, Seattle, WA,Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA
| | - Alex R. Paciorkowski
- Department of Neurology, University of Rochester Medical Center, Rochester, NY,Departments of Pediatrics and Biomedical Genetics, University of Rochester Medical Center, Rochester, NY,Center for Neural Development and Disease, University of Rochester Medical Center, Rochester, NY
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Zhong W, Johnson CM, Wu Y, Cui N, Xing H, Zhang S, Jiang C. Effects of early-life exposure to THIP on phenotype development in a mouse model of Rett syndrome. J Neurodev Disord 2016; 8:37. [PMID: 27777634 PMCID: PMC5069883 DOI: 10.1186/s11689-016-9169-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 10/04/2016] [Indexed: 01/15/2023] Open
Abstract
Background Rett syndrome (RTT) is a neurodevelopmental disorder caused mostly by disruptions in the MECP2 gene. MECP2-null mice show imbalances in neuronal excitability and synaptic communications. Several previous studies indicate that augmenting synaptic GABA receptors (GABAARs) can alleviate RTT-like symptoms in mice. In addition to the synaptic GABAARs, there is a group of GABAARs found outside the synaptic cleft with the capability to produce sustained inhibition, which may be potential therapeutic targets for the control of neuronal excitability in RTT. Methods Wild-type and MECP2-null mice were randomly divided into four groups, receiving the extrasynaptic GABAAR agonist 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol hydrochloride (THIP) and vehicle control, respectively. Low-dose THIP was administered to neonatal mice through lactation. RTT-like symptoms including lifespan, breathing, motor function, and social behaviors were studied when mice became mature. Changes in neuronal excitability and norepinephrine biosynthesis enzyme expression were studied in electrophysiology and molecular biology. Results With no evident sedation and other adverse side effects, early-life exposure to THIP extended the lifespan, alleviated breathing abnormalities, enhanced motor function, and improved social behaviors of MECP2-null mice. Such beneficial effects were associated with stabilization of locus coeruleus neuronal excitability and improvement of norepinephrine biosynthesis enzyme expression. Conclusions THIP treatment in early lives might be a therapeutic approach to RTT-like symptoms in MECP2-null mice and perhaps in people with RTT as well.
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Affiliation(s)
- Weiwei Zhong
- Department of Biology, Georgia State University, 100 Piedmont Avenue, Atlanta, GA 30302-4010 USA
| | | | - Yang Wu
- Department of Biology, Georgia State University, 100 Piedmont Avenue, Atlanta, GA 30302-4010 USA
| | - Ningren Cui
- Department of Biology, Georgia State University, 100 Piedmont Avenue, Atlanta, GA 30302-4010 USA
| | - Hao Xing
- Department of Biology, Georgia State University, 100 Piedmont Avenue, Atlanta, GA 30302-4010 USA
| | - Shuang Zhang
- Department of Biology, Georgia State University, 100 Piedmont Avenue, Atlanta, GA 30302-4010 USA
| | - Chun Jiang
- Department of Biology, Georgia State University, 100 Piedmont Avenue, Atlanta, GA 30302-4010 USA
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Oginsky MF, Cui N, Zhong W, Johnson CM, Jiang C. Hyperexcitability of Mesencephalic Trigeminal Neurons and Reorganization of Ion Channel Expression in a Rett Syndrome Model. J Cell Physiol 2016; 232:1151-1164. [PMID: 27670841 DOI: 10.1002/jcp.25589] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 09/06/2016] [Indexed: 12/30/2022]
Abstract
People with Rett syndrome (RTT) have defects in motor function also seen in Mecp2-null mice. Motor function depends on not only central motor commands but also sensory feedback that is vulnerable to changes in excitability of propriosensory neurons. Here we report evidence for hyperexcitability of mesencephalic trigeminal (Me5) neurons in Mecp2-null mice and a novel cellular mechanism for lowering its impact. In in vitro brain slices, the Me5 neurons in both Mecp2-/Y male and symptomatic Mecp2+/- female mice were overly excitable showing increased firing activity in comparison to their wild-type (WT) male and asymptomatic counterparts. In Mecp2-/Y males, Me5 neurons showed a reduced firing threshold. Consistently, the steady-state activation of voltage-gated Na+ currents (INa ) displayed a hyperpolarizing shift in the Mecp2-null neurons with no change in the INa density. This seems to be due to NaV1.1, SCN1B and SCN4B overexpression and NaV1.2 and SCN3B under-expression. In contrast to the hyperexcitability, the sag potential and postinhibitory rebound (PIR) were reduced in Mecp2-null mice. In voltage-clamp, the IH density was deficient by ∼33%, and the steady-state half-activation had a depolarizing shift of ∼10 mV in the Mecp2-null mice. Quantitative PCR analysis indicated that HCN2 was decreased, HCN1 was upregulated with no change in HCN4 in Mecp2-/Y mice compared to WT. Lastly, blocking IH reduced the firing rate much more in WT than in Mecp2-null neurons. These data suggest that the Mecp2 defect causes an increase in Me5 neuronal excitability likely attributable to alterations in INa , meanwhile IH is reduced likely altering neuronal excitability as well. J. Cell. Physiol. 232: 1151-1164, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Max F Oginsky
- Department of Biology, Georgia State University, Atlanta, Georgia
| | - Ningren Cui
- Department of Biology, Georgia State University, Atlanta, Georgia
| | - Weiwei Zhong
- Department of Biology, Georgia State University, Atlanta, Georgia
| | | | - Chun Jiang
- Department of Biology, Georgia State University, Atlanta, Georgia
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Kaufmann WE, Stallworth JL, Everman DB, Skinner SA. Neurobiologically-based treatments in Rett syndrome: opportunities and challenges. Expert Opin Orphan Drugs 2016; 4:1043-1055. [PMID: 28163986 PMCID: PMC5214376 DOI: 10.1080/21678707.2016.1229181] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 08/23/2016] [Indexed: 12/14/2022]
Abstract
Introduction: Rett syndrome (RTT) is an X-linked neurodevelopmental disorder that primarily affects females, typically resulting in a period of developmental regression in early childhood followed by stabilization and severe chronic cognitive, behavioral, and physical disability. No known treatment exists beyond symptomatic management, and while insights into the genetic cause, pathophysiology, neurobiology, and natural history of RTT have been gained, many challenges remain. Areas covered: Based on a comprehensive survey of the primary literature on RTT, this article describes and comments upon the general and unique features of the disorder, genetic and neurobiological bases of drug development, and the history of clinical trials in RTT, with an emphasis on drug trial design, outcome measures, and implementation. Expert opinion: Neurobiologically based drug trials are the ultimate goal in RTT, and due to the complexity and global nature of the disorder, drugs targeting both general mechanisms (e.g., growth factors) and specific systems (e.g., glutamate modulators) could be effective. Trial design should optimize data on safety and efficacy, but selection of outcome measures with adequate measurement properties, as well as innovative strategies, such as those enhancing synaptic plasticity and use of biomarkers, are essential for progress in RTT and other neurodevelopmental disorders.
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Affiliation(s)
- Walter E Kaufmann
- Center for Translational Research, Greenwood Genetic Center, Greenwood, SC, USA; Department of Neurology, Boston Children's Hospital, Boston, MA, USA
| | | | - David B Everman
- Center for Translational Research, Greenwood Genetic Center , Greenwood , SC , USA
| | - Steven A Skinner
- Center for Translational Research, Greenwood Genetic Center , Greenwood , SC , USA
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Djukic A, Holtzer R, Shinnar S, Muzumdar H, Rose SA, Mowrey W, Galanopoulou AS, Shinnar R, Jankowski JJ, Feldman JF, Pillai S, Moshé SL. Pharmacologic Treatment of Rett Syndrome With Glatiramer Acetate. Pediatr Neurol 2016; 61:51-7. [PMID: 27363291 DOI: 10.1016/j.pediatrneurol.2016.05.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2016] [Revised: 05/17/2016] [Accepted: 05/20/2016] [Indexed: 10/21/2022]
Abstract
BACKGROUND Rett syndrome (RTT) is a severe neurological disease that primarily affects females. The level of brain derived neurotropic factor (BDNF) expression directly correlates with the severity of RTT related symptoms. Because Glatiramer acetate (GA) stimulates secretion of BDNF in the brain, we conducted the study with the objective to assess its efficacy in improving gait velocity cognition, respiratory function, electroencephalographic findings, and quality of life in patients with RTT. METHODS Phase two, open label, single center trial. INCLUSION CRITERIA ambulatory girls with genetically confirmed RTT, 10 years or older. Pre- and post-treatment measures were compared using the non-parametric Wilcoxon signed rank sum test and paired t-tests. RESULTS Ten patients were enrolled and completed the trial. Gait velocity improved significantly (improvement range 13%-95%, p=0.03 for both tests) and emerged as an especially valuable outcome measure with excellent test- retest reliability of the 2 trials within sessions (intraclass correlation coefficient=0.94). Memory, and the breath holding index also improved significantly (p≤0.03). Epileptiform discharges decreased in all four patients who had them at baseline. There was a trend towards improved quality of life, which did not reach statistical significance. CONCLUSIONS This prospective open-label trial provides important preliminary information related to the efficacy of GA in improving gait velocity in female patients with RTT who are 10 years or older. The results of this trial justify the need for larger scale controlled trials of GA as well as provide a template for assessing the efficacy of other interventions in RTT.
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Affiliation(s)
- Aleksandra Djukic
- Saul R. Korey Department of Neurology, Albert Einstein College of Medicine, Bronx, New York; Rett Syndrome Center, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, New York; Department of Pediatrics, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, New York.
| | - Roee Holtzer
- Saul R. Korey Department of Neurology, Albert Einstein College of Medicine, Bronx, New York; Ferkauf Graduate School of Psychology of Yeshiva University, Bronx, New York
| | - Shlomo Shinnar
- Saul R. Korey Department of Neurology, Albert Einstein College of Medicine, Bronx, New York; Rett Syndrome Center, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, New York; Department of Pediatrics, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, New York; Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, New York
| | - Hiren Muzumdar
- Department of Pediatrics, Children's Hospital of Pittsburgh of UPMC, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Susan A Rose
- Department of Pediatrics, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, New York
| | - Wenzhu Mowrey
- Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, New York
| | - Aristea S Galanopoulou
- Saul R. Korey Department of Neurology, Albert Einstein College of Medicine, Bronx, New York; Rett Syndrome Center, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, New York; Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York
| | - Ruth Shinnar
- Saul R. Korey Department of Neurology, Albert Einstein College of Medicine, Bronx, New York
| | - Jeffrey J Jankowski
- Department of Social Sciences, Queensborough Community College, City University of New York, Bayside, New York
| | - Judith F Feldman
- Department of Pediatrics, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, New York
| | - Sophia Pillai
- Department of Pediatrics, Weill Cornell Medical College, New York, New York
| | - Solomon L Moshé
- Saul R. Korey Department of Neurology, Albert Einstein College of Medicine, Bronx, New York; Rett Syndrome Center, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, New York; Department of Pediatrics, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, New York; Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York
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Ohno K, Saito Y, Ueda R, Togawa M, Ohmae T, Matsuda E, Fujiyama M, Maegaki Y. Effect of Serotonin 1A Agonists and Selective Serotonin Reuptake Inhibitors on Behavioral and Nighttime Respiratory Symptoms in Rett Syndrome. Pediatr Neurol 2016; 60:54-59.e1. [PMID: 27212420 DOI: 10.1016/j.pediatrneurol.2016.03.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 03/25/2016] [Accepted: 03/26/2016] [Indexed: 01/15/2023]
Abstract
BACKGROUND Rett syndrome is characterized by psychomotor regression during early childhood, autistic-like behaviors, and aberrant breathing patterns. Dysfunction of the serotonergic system has been postulated to play a role in the pathophysiology of these symptoms. PATIENT DESCRIPTION We present an 11-year-old girl with Rett syndrome who exhibited marked respiratory symptoms, including frequent apneic events during sleep. She had been treated for these respiratory symptoms using noninvasive positive pressure ventilation since age six years. Treatment with serotonin 1A receptor agonist was initiated at age eight years, whereas treatment using a selective serotonin reuptake inhibitor began at age nine years. Noninvasive positive pressure ventilation therapy was effective in reducing symptoms of sleep apnea, and administration of serotonergic agents resulted in amelioration of sleep apneic events even in the absence of noninvasive positive pressure ventilation. In addition, improvements in hand stereotypy and social skills were observed after initiation of serotonin-based therapy. DISCUSSION The respiratory difficulties our patient experienced during non-rapid eye movement (REM) sleep are characteristic of post-sigh central apnea. Exaggerated activity of expiratory neurons during such apneic events has been observed in mouse models of Rett syndrome. We suggest that prescribed serotonergic agents might serve to inhibit such activity, attenuating the imbalance between inspiratory and expiratory neurons. These agents might also be useful in the treatment of autistic-like behaviors caused by impaired serotonergic transmission in the brain.
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Affiliation(s)
- Koyo Ohno
- Division of Child Neurology, Department of Brain and Neurosciences, Faculty of Medicine, Tottori University, Yonago, Japan.
| | - Yoshiaki Saito
- Division of Child Neurology, Department of Brain and Neurosciences, Faculty of Medicine, Tottori University, Yonago, Japan
| | - Riyo Ueda
- Division of Child Neurology, Department of Brain and Neurosciences, Faculty of Medicine, Tottori University, Yonago, Japan
| | - Masami Togawa
- Division of Child Neurology, Department of Brain and Neurosciences, Faculty of Medicine, Tottori University, Yonago, Japan; Department of Pediatrics, Tottori Prefectural Central Hospital, Tottori, Japan
| | - Takanori Ohmae
- Division of Child Neurology, Department of Brain and Neurosciences, Faculty of Medicine, Tottori University, Yonago, Japan
| | - Eriko Matsuda
- Division of Otolaryngology, Department of Head and Neck Surgery, Faculty of Medicine, Tottori University, Yonago, Japan
| | - Misato Fujiyama
- Division of Otolaryngology, Department of Head and Neck Surgery, Faculty of Medicine, Tottori University, Yonago, Japan
| | - Yoshihiro Maegaki
- Division of Child Neurology, Department of Brain and Neurosciences, Faculty of Medicine, Tottori University, Yonago, Japan
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71
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Patterson KC, Hawkins VE, Arps KM, Mulkey DK, Olsen ML. MeCP2 deficiency results in robust Rett-like behavioural and motor deficits in male and female rats. Hum Mol Genet 2016; 25:3303-3320. [PMID: 27329765 PMCID: PMC5179928 DOI: 10.1093/hmg/ddw179] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 05/18/2016] [Accepted: 06/08/2016] [Indexed: 11/12/2022] Open
Abstract
Since the identification of MECP2 as the causative gene in the majority of Rett Syndrome (RTT) cases, transgenic mouse models have played a critical role in our understanding of this disease. The use of additional mammalian RTT models offers the promise of further elucidating critical early mechanisms of disease as well as providing new avenues for translational studies. We have identified significant abnormalities in growth as well as motor and behavioural function in a novel zinc-finger nuclease model of RTT utilizing both male and female rats throughout development. Male rats lacking MeCP2 (Mecp2ZFN/y) were noticeably symptomatic as early as postnatal day 21, with most dying by postnatal day 55, while females lacking one copy of Mecp2 (Mecp2ZFN/+) displayed a more protracted disease course. Brain weights of Mecp2ZFN/y and Mecp2ZFN/+ rats were significantly reduced by postnatal day 14 and 21, respectively. Early motor and breathing abnormalities were apparent in Mecp2ZFN/y rats, whereas Mecp2ZFN/+ rats displayed functional irregularities later in development. The large size of this species will provide profound advantages in the identification of early disease mechanisms and the development of appropriately timed therapeutics. The current study establishes a foundational basis for the continued utilization of this rat model in future RTT research.
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Affiliation(s)
- Kelsey C Patterson
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Virginia E Hawkins
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA
| | - Kara M Arps
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Daniel K Mulkey
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA
| | - Michelle L Olsen
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
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72
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Kuo FS, Falquetto B, Chen D, Oliveira LM, Takakura AC, Mulkey DK. In vitro characterization of noradrenergic modulation of chemosensitive neurons in the retrotrapezoid nucleus. J Neurophysiol 2016; 116:1024-35. [PMID: 27306669 DOI: 10.1152/jn.00022.2016] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 06/09/2016] [Indexed: 01/08/2023] Open
Abstract
Chemosensitive neurons in the retrotrapezoid nucleus (RTN) regulate breathing in response to CO2/H(+) changes and serve as an integration center for other autonomic centers, including brain stem noradrenergic neurons. Norepinephrine (NE) contributes to respiratory control and chemoreception, and, since disruption of NE signaling may contribute to several breathing disorders, we sought to characterize effects of NE on RTN chemoreception. All neurons included in this study responded similarly to CO2/H(+) but showed differential sensitivity to NE; we found that NE activated (79%), inhibited (7%), or had no effect on activity (14%) of RTN chemoreceptors. The excitatory effect of NE on RTN chemoreceptors was dose dependent, retained in the presence of neurotransmitter receptor blockers, and could be mimicked and blocked by pharmacological manipulation of α1-adrenergic receptors (ARs). In addition, NE-activation was blunted by XE991 (KCNQ channel blocker), and partially occluded the firing response to serotonin, suggesting involvement of KCNQ channels. However, in whole cell voltage clamp, activation of α1-ARs decreased outward current and conductance by what appears to be a mixed effect on multiple channels. The inhibitory effect of NE on RTN chemoreceptors was blunted by an α2-AR antagonist. A third group of RTN chemoreceptors was insensitive to NE. We also found that chemosensitive RTN astrocytes do not respond to NE with a change in voltage or by releasing ATP to enhance activity of chemosensitive neurons. These results indicate NE modulates subsets of RTN chemoreceptors by mechanisms involving α1- and α2-ARs.
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Affiliation(s)
- Fu-Shan Kuo
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut; and
| | - Bárbara Falquetto
- Department of Pharmacology, University of Sao Paulo, Sao Paulo, Brazil
| | - Dawei Chen
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut; and
| | - Luiz M Oliveira
- Department of Pharmacology, University of Sao Paulo, Sao Paulo, Brazil
| | - Ana C Takakura
- Department of Pharmacology, University of Sao Paulo, Sao Paulo, Brazil
| | - Daniel K Mulkey
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut; and
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73
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Katz DM, Bird A, Coenraads M, Gray SJ, Menon DU, Philpot BD, Tarquinio DC. Rett Syndrome: Crossing the Threshold to Clinical Translation. Trends Neurosci 2016; 39:100-113. [PMID: 26830113 PMCID: PMC4924590 DOI: 10.1016/j.tins.2015.12.008] [Citation(s) in RCA: 109] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 12/14/2015] [Accepted: 12/15/2015] [Indexed: 12/11/2022]
Abstract
Lying at the intersection between neurobiology and epigenetics, Rett syndrome (RTT) has garnered intense interest in recent years, not only from a broad range of academic scientists, but also from the pharmaceutical and biotechnology industries. In addition to the critical need for treatments for this devastating disorder, optimism for developing RTT treatments derives from a unique convergence of factors, including a known monogenic cause, reversibility of symptoms in preclinical models, a strong clinical research infrastructure highlighted by an NIH-funded natural history study and well-established clinics with significant patient populations. Here, we review recent advances in understanding the biology of RTT, particularly promising preclinical findings, lessons from past clinical trials, and critical elements of trial design for rare disorders.
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Affiliation(s)
- David M Katz
- Departments of Neurosciences and Psychiatry, Case Western Reserve University School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106, USA.
| | - Adrian Bird
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, UK
| | - Monica Coenraads
- Rett Syndrome Research Trust, 67 Under Cliff Road, Trumbull, CT 06611, USA
| | - Steven J Gray
- Gene Therapy Center and Department of Ophthalmology, University of North Carolina, Chapel Hill, NC USA
| | - Debashish U Menon
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Benjamin D Philpot
- Department of Cell Biology and Physiology, Neuroscience Center, and Carolina Institute for Developmental Disabilities, UNC School of Medicine, Chapel Hill, NC 27599, USA
| | - Daniel C Tarquinio
- Children's Healthcare of Atlanta, Emory University, 1605 Chantilly Drive NE, Atlanta, GA 30324, USA
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Abdala AP, Toward MA, Dutschmann M, Bissonnette JM, Paton JFR. Deficiency of GABAergic synaptic inhibition in the Kölliker-Fuse area underlies respiratory dysrhythmia in a mouse model of Rett syndrome. J Physiol 2015; 594:223-37. [PMID: 26507912 DOI: 10.1113/jp270966] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 10/23/2015] [Indexed: 12/31/2022] Open
Abstract
KEY POINTS Life threatening breathing irregularity and central apnoeas are highly prevalent in children suffering from Rett syndrome. Abnormalities in inhibitory synaptic transmission have been associated with the physiopathology of this syndrome, and may underlie the respiratory disorder. In a mouse model of Rett syndrome, GABAergic terminal projections are markedly reduced in the Kölliker-Fuse nucleus (KF) in the dorsolateral pons, an important centre for control of respiratory rhythm regularity. Administration of a drug that augments endogenous GABA localized to this region of the pons reduced the incidence of apnoea and the respiratory irregularity of Rett female mice. Conversely, the respiratory disorder was recapitulated by blocking GABAergic transmission in the KF area of healthy rats. This study helps us understand the mechanism for generation of respiratory abnormality in Rett syndrome, pinpoints a brain site responsible and provides a clear anatomical target for the development of a translatable drug treatment. Central apnoeas and respiratory irregularity are a common feature in Rett syndrome (RTT), a neurodevelopmental disorder most often caused by mutations in the methyl-CpG-binding protein 2 gene (MECP2). We used a MECP2 deficient mouse model of RTT as a strategy to obtain insights into the neurobiology of the disease and into mechanisms essential for respiratory rhythmicity during normal breathing. Previously, we showed that, systemic administration of a GABA reuptake blocker in MECP2 deficient mice markedly reduced the occurrence of central apnoeas. Further, we found that, during central apnoeas, post-inspiratory drive (adductor motor) to the upper airways was enhanced in amplitude and duration in Mecp2 heterozygous female mice. Since the pontine Kölliker-Fuse area (KF) drives post-inspiration, suppresses inspiration, and can reset the respiratory oscillator phase, we hypothesized that synaptic inhibition in this area is essential for respiratory rhythm regularity. In this study, we found that: (i) Mecp2 heterozygous mice showed deficiency of GABA perisomatic bouton-like puncta and processes in the KF nucleus; (ii) blockade of GABA reuptake in the KF of RTT mice reduced breathing irregularity; (iii) conversely, blockade of GABAA receptors in the KF of healthy rats mimicked the RTT respiratory phenotype of recurrent central apnoeas and prolonged post-inspiratory activity. Our results show that reductions in synaptic inhibition within the KF induce rhythm irregularity whereas boosting GABA transmission reduces respiratory arrhythmia in a murine model of RTT. Our data suggest that manipulation of synaptic inhibition in KF may be a clinically important strategy for alleviating the life threatening respiratory disorders in RTT.
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Affiliation(s)
- Ana Paula Abdala
- School of Physiology and Pharmacology, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
| | - Marie A Toward
- School of Physiology and Pharmacology, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
| | - Mathias Dutschmann
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Gate 11, Royal Parade, Victoria 3052, Australia
| | - John M Bissonnette
- Department of Obstetrics and Gynecology, Oregon Health and Science University, Portland, OR, 97239, USA
| | - Julian F R Paton
- School of Physiology and Pharmacology, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
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75
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Gadalla KKE, Ross PD, Hector RD, Bahey NG, Bailey MES, Cobb SR. Gene therapy for Rett syndrome: prospects and challenges. FUTURE NEUROLOGY 2015. [DOI: 10.2217/fnl.15.29] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Rett syndrome (RTT) is a neurological disorder that affects females and is caused by loss-of-function mutations in the X-linked gene MECP2. Deletion of Mecp2 in mice results in a constellation of neurological features that resemble those seen in RTT patients. Experiments in mice have demonstrated that restoration of MeCP2, even at adult stages, reverses several aspects of the RTT-like pathology suggesting that the disorder may be inherently treatable. This has provided an impetus to explore several therapeutic approaches targeting RTT at the level of the gene, including gene therapy, activation of MECP2 on the inactive X chromosome and read-through and repair of RTT-causing mutations. Here, we review these different strategies and the challenges of gene-based approaches in RTT.
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Affiliation(s)
- Kamal KE Gadalla
- University of Glasgow, Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, Glasgow, UK
- Pharmacology Department, Faculty of Medicine, Tanta University, Egypt
| | - Paul D Ross
- University of Glasgow, Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, Glasgow, UK
| | - Ralph D Hector
- University of Glasgow, Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, Glasgow, UK
| | - Noha G Bahey
- University of Glasgow, Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, Glasgow, UK
- Histology Department, Faculty of Medicine, Tanta University, Egypt
| | - Mark ES Bailey
- School of Life Sciences, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Stuart R Cobb
- University of Glasgow, Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, Glasgow, UK
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76
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Pecorelli A, Cervellati F, Belmonte G, Montagner G, Waldon P, Hayek J, Gambari R, Valacchi G. Cytokines profile and peripheral blood mononuclear cells morphology in Rett and autistic patients. Cytokine 2015; 77:180-8. [PMID: 26471937 DOI: 10.1016/j.cyto.2015.10.002] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Revised: 09/16/2015] [Accepted: 10/07/2015] [Indexed: 12/25/2022]
Abstract
A potential role for immune dysfunction in autism spectrum disorders (ASD) has been well established. However, immunological features of Rett syndrome (RTT), a genetic neurodevelopmental disorder closely related to autism, have not been well addressed yet. By using multiplex Luminex technology, a panel of 27 cytokines and chemokines was evaluated in serum from 10 RTT patients with confirmed diagnosis of MECP2 mutation (typical RTT), 12 children affected by classic autistic disorder and 8 control subjects. The cytokine/chemokine gene expression was assessed by real time PCR on mRNA of isolated peripheral blood mononuclear cells (PBMCs). Moreover, ultrastructural analysis of PBMCs was performed using transmission electron microscopy (TEM). Significantly higher serum levels of interleukin-8 (IL-8), IL-9, IL-13 were detected in RTT compared to control subjects, and IL-15 shows a trend toward the upregulation in RTT. In addition, IL-1β and VEGF were the only down-regulated cytokines in autistic patients with respect to RTT. No difference in cytokine/chemokine profile between autistic and control groups was detected. These data were also confirmed by ELISA real time PCR. At the ultrastructural level, the most severe morphological abnormalities were observed in mitochondria of both RTT and autistic PBMCs. In conclusion, our study shows a deregulated cytokine/chemokine profile together with morphologically altered immune cells in RTT. Such abnormalities were not quite as evident in autistic subjects. These findings indicate a possible role of immune dysfunction in RTT making the clinical features of this pathology related also to the immunology aspects, suggesting, therefore, novel possible therapeutic interventions for this disorder.
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Affiliation(s)
- Alessandra Pecorelli
- Child Neuropsychiatry Unit, University General Hospital, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Franco Cervellati
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Giuseppe Belmonte
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Giulia Montagner
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | | | - Joussef Hayek
- Child Neuropsychiatry Unit, University General Hospital, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Roberto Gambari
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Giuseppe Valacchi
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy; Department of Food and Nutrition, Kyung Hee University, Seoul, South Korea.
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77
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Du X, Hill R. 7,8-Dihydroxyflavone as a pro-neurotrophic treatment for neurodevelopmental disorders. Neurochem Int 2015. [DOI: 10.1016/j.neuint.2015.07.021] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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78
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Garg SK, Lioy DT, Knopp SJ, Bissonnette JM. Conditional depletion of methyl-CpG-binding protein 2 in astrocytes depresses the hypercapnic ventilatory response in mice. J Appl Physiol (1985) 2015. [DOI: 10.1152/japplphysiol.00411.2015] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mice that are deficient in the transcription factor methyl-CpG-binding protein 2 (MeCP2) have a depressed hypercapnic ventilatory response (HCVR). The expression of MeCP2 can be selectively removed from astrocytes or neurons, thus offering a tool to dissect the role of this transcription factor in astrocytes from that in neurons. Studies were carried out in the progeny of mice that were a cross between those harboring a tamoxifen (TAM)-inducible Cre recombinase transgene driven by the human astrocytic glial fibrillary acidic protein (hGFAP) promoter, or Cre recombinase under control of the synapsin promoter, with mice containing a Cre-excisable exon III in the Mecp2 gene. The TAM-conditional excision of the Mecp2 exon allowed the respiratory CO2 response to be studied in the same animals before and after selective depletion of MeCP2 in astrocytes. Immunohistochemistry showed that following TAM treatment only ∼20% of GFAP-labeled cells in the retrotrapazoid nucleus and in the raphé magnus were positive for MeCP2. The slope of the relative increase in minute ventilation as a function of 1, 3, and 5% inspired CO2 was depressed in mice with depleted astrocyte MeCP2 compared with wild-type littermates. In contrast, selective depletion of MeCP2 in neurons did not significantly affect slope. While neurons which constitute the respiratory network ultimately determine the ventilatory response to CO2, this study demonstrates that loss of MeCP2 in astrocytes alone is sufficient to result in a dramatic attenuation of the HCVR. We propose that the glial contribution to HCVR is under the control of the MeCP2 gene.
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Affiliation(s)
| | | | | | - John M. Bissonnette
- Department of Obstetrics and Gynecology, and
- Department of Cell, Developmental and Cancer Biology, Oregon Health and Science University, Portland, Oregon
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79
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Johnson CM, Cui N, Zhong W, Oginsky MF, Jiang C. Breathing abnormalities in a female mouse model of Rett syndrome. J Physiol Sci 2015; 65:451-9. [PMID: 26071253 PMCID: PMC6415540 DOI: 10.1007/s12576-015-0384-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Accepted: 05/24/2015] [Indexed: 10/23/2022]
Abstract
Rett syndrome (RTT) is a female neurodevelopmental disease with breathing abnormalities. To understand whether breathing defects occur in the early lives of a group of female Mecp2(+/-) mice, a mouse model of RTT, and what percentage of mice shows RTT-like breathing abnormality, breathing activity was measured by plethysmography in conscious mice. Breathing frequency variation and central apnea in a group of Mecp2(+/-) females displayed a distribution pattern similar to Mecp2(-/Y) males, while the rest resembled the wild-type mice. Similar results were obtained using the k-mean clustering statistics analysis. With two independent methods, about 20% of female Mecp2(+/-) mice showed RTT-like breathing abnormalities that began as early as 3 weeks of age in the Mecp2(+/-) mice, and were suppressed with 3% CO2. The finding that only a small proportion of Mecp2(+/-) mice develops RTT-like breathing abnormalities suggests incomplete allele inactivation in the RTT-model Mecp2(+/-) mice.
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Affiliation(s)
- Christopher M. Johnson
- Department of Biology, Georgia State University, 50 Decatur Street, Atlanta, GA 30302 USA
| | - Ningren Cui
- Department of Biology, Georgia State University, 50 Decatur Street, Atlanta, GA 30302 USA
| | - Weiwei Zhong
- Department of Biology, Georgia State University, 50 Decatur Street, Atlanta, GA 30302 USA
| | - Max F. Oginsky
- Department of Biology, Georgia State University, 50 Decatur Street, Atlanta, GA 30302 USA
| | - Chun Jiang
- Department of Biology, Georgia State University, 50 Decatur Street, Atlanta, GA 30302 USA
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80
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Turovsky E, Karagiannis A, Abdala AP, Gourine AV. Impaired CO2 sensitivity of astrocytes in a mouse model of Rett syndrome. J Physiol 2015; 593:3159-68. [PMID: 25981852 PMCID: PMC4532534 DOI: 10.1113/jp270369] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Accepted: 05/11/2015] [Indexed: 12/13/2022] Open
Abstract
Rett syndrome, a prototypical neurological disorder caused by loss of function of the transcriptional regulator methyl-CpG-binding protein 2 (MeCP2) gene, is associated with a severely disordered breathing pattern and reduced ventilatory CO2 sensitivity. In a mouse model of Rett syndrome (MeCP2 knockout), re-introduction of the MeCP2 gene selectively in astrocytes rescues normal respiratory phenotype. In the present study we determined whether the metabolic and/or signalling functions of astrocytes are affected by testing the hypotheses that in conditions of MeCP2 deficiency, medullary astrocytes are unable to produce/release appropriate amounts of lactate or detect changes in PCO2/[H(+) ], or both. No differences in tonic or hypoxia-induced release of lactate from the ventral surface of the medulla oblongata or cerebral cortex in brain slices of MeCP2-knockout and wild-type mice were found. In brainstem slices of wild-type mice, respiratory acidosis triggered robust elevations in [Ca(2+) ]i in astrocytes residing near the ventral surface of the medulla oblongata. The magnitude of CO2 -induced [Ca(2+) ]i responses in medullary astrocytes was markedly reduced in conditions of MeCP2 deficiency, whereas [Ca(2+) ]i responses to ATP were unaffected. These data suggest that (i) metabolic function of astrocytes in releasing lactate into the extracellular space is not affected by MeCP2 deficiency, and (ii) MeCP2 deficiency impairs the ability of medullary astrocytes to sense changes in PCO2/[H(+) ]. Taken together with the evidence of severely blunted ventilatory sensitivity to CO2 in mice with conditional MeCP2 deletion in astroglia, these data support the hypothesis of an important role played by astrocytes in central respiratory CO2 /pH chemosensitivity.
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Affiliation(s)
- Egor Turovsky
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK.,Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Russia
| | - Anastassios Karagiannis
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Ana Paula Abdala
- School of Physiology & Pharmacology, University of Bristol, Bristol, BS8 1TD, UK
| | - Alexander V Gourine
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK
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81
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Lee BH, Smith T, Paciorkowski AR. Autism spectrum disorder and epilepsy: Disorders with a shared biology. Epilepsy Behav 2015; 47:191-201. [PMID: 25900226 PMCID: PMC4475437 DOI: 10.1016/j.yebeh.2015.03.017] [Citation(s) in RCA: 103] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 03/06/2015] [Accepted: 03/13/2015] [Indexed: 12/17/2022]
Abstract
There is an increasing recognition of clinical overlap in patients presenting with epilepsy and autism spectrum disorder (ASD), and a great deal of new information regarding the genetic causes of both disorders is available. Several biological pathways appear to be involved in both disease processes, including gene transcription regulation, cellular growth, synaptic channel function, and maintenance of synaptic structure. We review several genetic disorders where ASD and epilepsy frequently co-occur, and we discuss the screening tools available for practicing neurologists and epileptologists to help determine which patients should be referred for formal ASD diagnostic evaluation. Finally, we make recommendations regarding the workflow of genetic diagnostic testing available for children with both ASD and epilepsy. This article is part of a Special Issue entitled "Autism and Epilepsy".
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Affiliation(s)
- Bo Hoon Lee
- Department of Pediatrics, University of Rochester Medical Center, Rochester, NY, USA
| | - Tristram Smith
- Division of Neurodevelopmental and Behavioral Pediatrics, Department of Pediatrics, University of Rochester Medical Center, Rochester, NY, USA
| | - Alex R Paciorkowski
- Department of Pediatrics, University of Rochester Medical Center, Rochester, NY, USA; Department of Neurology, University of Rochester Medical Center, Rochester, NY, USA; Department of Biomedical Genetics, University of Rochester Medical Center, Rochester, NY, USA; Center for Neural Development and Disease, University of Rochester Medical Center, Rochester, NY, USA.
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82
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Abstract
There is a close relationship between sleep and childhood neurodevelopmental/neurodegenerative disorders. Understanding the sleep issues may provide greater insight into pathophysiology and treatment of these disorders.
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83
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Kron M, Lang M, Adams IT, Sceniak M, Longo F, Katz DM. A BDNF loop-domain mimetic acutely reverses spontaneous apneas and respiratory abnormalities during behavioral arousal in a mouse model of Rett syndrome. Dis Model Mech 2015; 7:1047-55. [PMID: 25147297 PMCID: PMC4142725 DOI: 10.1242/dmm.016030] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Reduced levels of brain-derived neurotrophic factor (BDNF) are thought to contribute to the pathophysiology of Rett syndrome (RTT), a severe neurodevelopmental disorder caused by loss-of-function mutations in the gene encoding methyl-CpG-binding protein 2 (MeCP2). In Mecp2 mutant mice, BDNF deficits have been associated with breathing abnormalities, a core feature of RTT, as well as with synaptic hyperexcitability within the brainstem respiratory network. Application of BDNF can reverse hyperexcitability in acute brainstem slices from Mecp2-null mice, suggesting that therapies targeting BDNF or its receptor, TrkB, could be effective at acute reversal of respiratory abnormalities in RTT. Therefore, we examined the ability of LM22A-4, a small-molecule BDNF loop-domain mimetic and TrkB partial agonist, to modulate synaptic excitability within respiratory cell groups in the brainstem nucleus tractus solitarius (nTS) and to acutely reverse abnormalities in breathing at rest and during behavioral arousal in Mecp2 mutants. Patch-clamp recordings in Mecp2-null brainstem slices demonstrated that LM22A-4 decreases excitability at primary afferent synapses in the nTS by reducing the amplitude of evoked excitatory postsynaptic currents and the frequency of spontaneous and miniature excitatory postsynaptic currents. In vivo, acute treatment of Mecp2-null and -heterozygous mutants with LM22A-4 completely eliminated spontaneous apneas in resting animals, without sedation. Moreover, we demonstrate that respiratory dysregulation during behavioral arousal, a feature of human RTT, is also reversed in Mecp2 mutants by acute treatment with LM22A-4. Together, these data support the hypothesis that reduced BDNF signaling and respiratory dysfunction in RTT are linked, and establish the proof-of-concept that treatment with a small-molecule structural mimetic of a BDNF loop domain and a TrkB partial agonist can acutely reverse abnormal breathing at rest and in response to behavioral arousal in symptomatic RTT mice.
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Affiliation(s)
- Miriam Kron
- Department of Neurosciences, Case Western Reserve University School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Min Lang
- Department of Neurosciences, Case Western Reserve University School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Ian T Adams
- Department of Neurosciences, Case Western Reserve University School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Michael Sceniak
- Department of Neurosciences, Case Western Reserve University School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Frank Longo
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA 94305, USA
| | - David M Katz
- Department of Neurosciences, Case Western Reserve University School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106, USA
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Sceniak MP, Lang M, Enomoto AC, James Howell C, Hermes DJ, Katz DM. Mechanisms of Functional Hypoconnectivity in the Medial Prefrontal Cortex of Mecp2 Null Mice. Cereb Cortex 2015; 26:1938-1956. [PMID: 25662825 DOI: 10.1093/cercor/bhv002] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Frontal cortical dysfunction is thought to contribute to cognitive and behavioral features of autism spectrum disorders; however, underlying mechanisms are poorly understood. The present study sought to define how loss of Mecp2, the gene mutated in Rett syndrome (RTT), disrupts function in the murine medial prefrontal cortex (mPFC) using acute brain slices and behavioral testing. Compared with wildtype, pyramidal neurons in the Mecp2 null mPFC exhibit significant reductions in excitatory postsynaptic currents, the duration of excitatory UP-states, evoked population activity, and the ratio of NMDA:AMPA currents, as well as an increase in the relative fraction of NR2B currents. These functional changes are associated with reductions in the density of excitatory dendritic spines, the ratio of vesicular glutamate to GABA transporters and GluN1 expression. In contrast to recent reports on circuit defects in other brain regions, we observed no effect of Mecp2 loss on inhibitory synaptic currents or expression of the inhibitory marker parvalbumin. Consistent with mPFC hypofunction, Mecp2 nulls exhibit respiratory dysregulation in response to behavioral arousal. Our data highlight functional hypoconnectivity in the mPFC as a potential substrate for behavioral disruption in RTT and other disorders associated with reduced expression of Mecp2 in frontal cortical regions.
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Affiliation(s)
- Michael P Sceniak
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Min Lang
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Addison C Enomoto
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - C James Howell
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Douglas J Hermes
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - David M Katz
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
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Funk GD, Rajani V, Alvares TS, Revill AL, Zhang Y, Chu NY, Biancardi V, Linhares-Taxini C, Katzell A, Reklow R. Neuroglia and their roles in central respiratory control; an overview. Comp Biochem Physiol A Mol Integr Physiol 2015; 186:83-95. [PMID: 25634606 DOI: 10.1016/j.cbpa.2015.01.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2014] [Revised: 01/15/2015] [Accepted: 01/16/2015] [Indexed: 01/12/2023]
Abstract
While once viewed as mere housekeepers, providing structural and metabolic support for neurons, it is now clear that neuroglia do much more. Phylogenetically, they have undergone enormous proliferation and diversification as central nervous systems grew in their complexity. In addition, they: i) are morphologically and functionally diverse; ii) play numerous, vital roles in maintaining CNS homeostasis; iii) are key players in brain development and responses to injury; and, iv) via gliotransmission, are likely participants in information processing. In this review, we discuss the diverse roles of neuroglia in maintaining homeostasis in the CNS, their evolutionary origins, the different types of neuroglia and their functional significance for respiratory control, and finally consider evidence that they contribute to the processing of chemosensory information in the respiratory network and the homeostatic control of blood gases.
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Affiliation(s)
- Gregory D Funk
- Department of Physiology, Neuroscience and Mental Health Institute, Women and Children's Health Research Institute (WCHRI), Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.
| | - Vishaal Rajani
- Department of Physiology, Neuroscience and Mental Health Institute, Women and Children's Health Research Institute (WCHRI), Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Tucaauê S Alvares
- Department of Physiology, Neuroscience and Mental Health Institute, Women and Children's Health Research Institute (WCHRI), Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Ann L Revill
- Department of Physiology, Neuroscience and Mental Health Institute, Women and Children's Health Research Institute (WCHRI), Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Yong Zhang
- Department of Physiology, Neuroscience and Mental Health Institute, Women and Children's Health Research Institute (WCHRI), Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Nathan Y Chu
- Department of Physiology, Neuroscience and Mental Health Institute, Women and Children's Health Research Institute (WCHRI), Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Vivian Biancardi
- Department of Physiology, Neuroscience and Mental Health Institute, Women and Children's Health Research Institute (WCHRI), Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada; Department of Animal Morphology and Physiology, Fac. de Ciências Agrárias e Veterinárias/UNESP, Via de Acesso Paulo Donato Castellane km 05, Jaboticabal, SP 14884-900, Brazil
| | - Camila Linhares-Taxini
- Department of Physiology, Neuroscience and Mental Health Institute, Women and Children's Health Research Institute (WCHRI), Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada; Department of Animal Morphology and Physiology, Fac. de Ciências Agrárias e Veterinárias/UNESP, Via de Acesso Paulo Donato Castellane km 05, Jaboticabal, SP 14884-900, Brazil
| | - Alexis Katzell
- Department of Physiology, Neuroscience and Mental Health Institute, Women and Children's Health Research Institute (WCHRI), Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Robert Reklow
- Department of Physiology, Neuroscience and Mental Health Institute, Women and Children's Health Research Institute (WCHRI), Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
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86
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Karmaniolou I, Krishnan R, Galtrey E, Cleland S, Vijayaraghavan R. Perioperative management and outcome of patients with Rett syndrome undergoing scoliosis surgery: a retrospective review. J Anesth 2015; 29:492-8. [PMID: 25617158 DOI: 10.1007/s00540-015-1974-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Accepted: 01/04/2015] [Indexed: 11/29/2022]
Abstract
BACKGROUND Rett syndrome is a rare genetically inherited neuromuscular disorder exclusively affecting female patients. Progressive scoliosis is one of the main features of the disease and affected individuals are very likely to need spine correction surgery. METHODS We undertook a retrospective notes review of patients with Rett syndrome who had undergone spine surgery from 2005 to 2013. Patients were identified through the hospital's electronic records. The aim of the present study was to identify the anesthetic implications encountered and the perioperative adverse events, in an effort to improve perioperative management and reduce complications. RESULT We identified twenty-four children who had 29 procedures in total in this period. Frequent chest infections and poorly controlled epilepsy were the main preoperative findings. There were no adverse events during induction and intubation. Common anesthetic/analgesic drugs were used throughout. Postoperatively, gastrointestinal and respiratory tract complications were the most common. Mean intensive care unit stay was 8.1 days and mean time to discharge from hospital was 26.5 days. We had one in-hospital death. CONCLUSIONS Our case series demonstrates a high incidence of complications in this subpopulation, mainly postoperative. Extreme postoperative vigilance is required and recovery in a high dependency unit is highly recommended.
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87
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Wegener E, Brendel C, Fischer A, Hülsmann S, Gärtner J, Huppke P. Characterization of the MeCP2R168X knockin mouse model for Rett syndrome. PLoS One 2014; 9:e115444. [PMID: 25541993 PMCID: PMC4277341 DOI: 10.1371/journal.pone.0115444] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Accepted: 11/24/2014] [Indexed: 11/19/2022] Open
Abstract
Rett syndrome, one of the most common causes of mental retardation in females, is caused by mutations in the X chromosomal gene MECP2. Mice deficient for MeCP2 recapitulate some of the symptoms seen in patients with Rett syndrome. It has been shown that reactivation of silent MECP2 alleles can reverse some of the symptoms in these mice. We have generated a knockin mouse model for translational research that carries the most common nonsense mutation in Rett syndrome, R168X. In this article we describe the phenotype of this mouse model. In male MeCP2(R168X) mice life span was reduced to 12-14 weeks and bodyweight was significantly lower than in wild type littermates. First symptoms including tremor, hind limb clasping and inactivity occurred at age 27 days. At age 6 weeks nest building, rotarod, open-field and elevated plus maze experiments showed impaired motor performance, reduced activity and decreased anxiety-like behavior. Plethysmography at the same time showed apneas and irregular breathing with reduced frequency. Female MeCP2R168X mice showed no significant abnormalities except decreased performance on the rotarod at age 9 months. In conclusion we show that the male MeCP2(R168X) mice have a phenotype similar to that seen in MECP2 knockout mouse models and are therefore well suited for translational research. The female mice, however, have a much milder and less constant phenotype making such research with this mouse model more challenging.
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Affiliation(s)
- Eike Wegener
- University Medical Center Göttingen, Department of Child and Adolescent Health – Division of Neuropediatrics, Göttingen, Germany
| | - Cornelia Brendel
- University Medical Center Göttingen, Department of Child and Adolescent Health – Division of Neuropediatrics, Göttingen, Germany
| | - Andre Fischer
- German Center for Neurodegenerative Diseases, Göttingen, Germany
- University Medical Center Göttingen, Department for Psychiatry and Psychotherapy, Göttingen, Germany
| | - Swen Hülsmann
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany
| | - Jutta Gärtner
- University Medical Center Göttingen, Department of Child and Adolescent Health – Division of Neuropediatrics, Göttingen, Germany
| | - Peter Huppke
- University Medical Center Göttingen, Department of Child and Adolescent Health – Division of Neuropediatrics, Göttingen, Germany
- * E-mail:
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88
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Urbanowicz A, Downs J, Girdler S, Ciccone N, Leonard H. Aspects of speech-language abilities are influenced by MECP2 mutation type in girls with Rett syndrome. Am J Med Genet A 2014; 167A:354-62. [PMID: 25428820 DOI: 10.1002/ajmg.a.36871] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Accepted: 10/11/2014] [Indexed: 12/25/2022]
Abstract
This study investigates relationships between methyl-CpG-binding protein 2 gene (MECP2) mutation type and speech-language abilities in girls with Rett syndrome. Cross-sectional data on 766 girls, aged 15 years and under, with genetically confirmed Rett syndrome was obtained from the Australian Rett Syndrome Database (ARSD) (n = 244) and the International Rett Syndrome Phenotype Database (InterRett) (n = 522). Relationships between MECP2 mutation type and age of regression in speech-language abilities, and the level of speech-language abilities before and after this regression were investigated. The females had a median age of 4.95 years in the ARSD and 5.25 years in InterRett. The majority (89%, 685/766) acquired speech-language abilities in the form of babble or words at some point in time. Of those who acquired babble or words, 85% (581/685) experienced a regression in these abilities. Those with a p.Arg133Cys mutation were the most likely to use one or more words, prior to (RRR = 3.45; 95% CI 1.15-10.41) and after (RRR = 5.99; 95% CI 2.00-17.92), speech-language regression. Girls with Rett syndrome vary in their use of speech and language, and in their experience of speech-language regression and these variations are partly explained by genotype.
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Affiliation(s)
- Anna Urbanowicz
- Telethon Kids Institute, The University of Western Australia, Australia; School of Exercise and Health Sciences, Edith Cowan University, Perth, WA, Australia
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89
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Abdala AP, Bissonnette JM, Newman-Tancredi A. Pinpointing brainstem mechanisms responsible for autonomic dysfunction in Rett syndrome: therapeutic perspectives for 5-HT1A agonists. Front Physiol 2014; 5:205. [PMID: 24910619 PMCID: PMC4038922 DOI: 10.3389/fphys.2014.00205] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Accepted: 05/12/2014] [Indexed: 12/26/2022] Open
Abstract
Rett syndrome is a neurological disorder caused by loss of function of methyl-CpG-binding protein 2 (MeCP2). Reduced function of this ubiquitous transcriptional regulator has a devastating effect on the central nervous system. One of the most severe and life-threatening presentations of this syndrome is brainstem dysfunction, which results in autonomic disturbances such as breathing deficits, typified by episodes of breathing cessation intercalated with episodes of hyperventilation or irregular breathing. Defects in numerous neurotransmitter systems have been observed in Rett syndrome both in animal models and patients. Here we dedicate special attention to serotonin due to its role in promoting regular breathing, increasing vagal tone, regulating mood, alleviating Parkinsonian-like symptoms and potential for therapeutic translation. A promising new symptomatic strategy currently focuses on regulation of serotonergic function using highly selective serotonin type 1A (5-HT1A) “biased agonists.” We address this newly emerging therapy for respiratory brainstem dysfunction and challenges for translation with a holistic perspective of Rett syndrome, considering potential mood and motor effects.
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Affiliation(s)
- Ana P Abdala
- School of Physiology and Pharmacology, University of Bristol Bristol, UK
| | - John M Bissonnette
- Department of Obstetrics and Gynecology, Oregon Health and Science University Portland, OR, USA
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90
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Seltzer LE, Paciorkowski AR. Genetic disorders associated with postnatal microcephaly. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2014; 166C:140-55. [PMID: 24839169 DOI: 10.1002/ajmg.c.31400] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Several genetic disorders are characterized by normal head size at birth, followed by deceleration in head growth resulting in postnatal microcephaly. Among these are classic disorders such as Angelman syndrome and MECP2-related disorder (formerly Rett syndrome), as well as more recently described clinical entities associated with mutations in CASK, CDKL5, CREBBP, and EP300 (Rubinstein-Taybi syndrome), FOXG1, SLC9A6 (Christianson syndrome), and TCF4 (Pitt-Hopkins syndrome). These disorders can be identified clinically by phenotyping across multiple neurodevelopmental and neurobehavioral realms, and enough data are available to recognize these postnatal microcephaly disorders as separate diagnostic entities in their own right. A second diagnostic grouping, comprised of Warburg MICRO syndrome, Cockayne syndrome, and Cerebral-oculo-facial skeletal syndrome, share similar features of somatic growth failure, ophthalmologic, and dysmorphologic features. Many postnatal microcephaly syndromes are caused by mutations in genes important in the regulation of gene expression in the developing forebrain and hindbrain, although important synaptic structural genes also play a role. This is an emerging group of disorders with a fascinating combination of brain malformations, specific epilepsies, movement disorders, and other complex neurobehavioral abnormalities.
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91
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Oxidative brain damage in Mecp2-mutant murine models of Rett syndrome. Neurobiol Dis 2014; 68:66-77. [PMID: 24769161 PMCID: PMC4076513 DOI: 10.1016/j.nbd.2014.04.006] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 03/10/2014] [Accepted: 04/14/2014] [Indexed: 12/03/2022] Open
Abstract
Rett syndrome (RTT) is a rare neurodevelopmental disorder affecting almost exclusively females, caused in the overwhelming majority of the cases by loss-of-function mutations in the gene encoding methyl-CpG binding protein 2 (MECP2). High circulating levels of oxidative stress (OS) markers in patients suggest the involvement of OS in the RTT pathogenesis. To investigate the occurrence of oxidative brain damage in Mecp2 mutant mouse models, several OS markers were evaluated in whole brains of Mecp2-null (pre-symptomatic, symptomatic, and rescued) and Mecp2-308 mutated (pre-symptomatic and symptomatic) mice, and compared to those of wild type littermates. Selected OS markers included non-protein-bound iron, isoprostanes (F2-isoprostanes, F4-neuroprostanes, F2-dihomo-isoprostanes) and 4-hydroxy-2-nonenal protein adducts. Our findings indicate that oxidative brain damage 1) occurs in both Mecp2-null (both −/y and stop/y) and Mecp2-308 (both 308/y males and 308/+ females) mouse models of RTT; 2) precedes the onset of symptoms in both Mecp2-null and Mecp2-308 models; and 3) is rescued by Mecp2 brain specific gene reactivation. Our data provide direct evidence of the link between Mecp2 deficiency, oxidative stress and RTT pathology, as demonstrated by the rescue of the brain oxidative homeostasis following brain-specifically Mecp2-reactivated mice. The present study indicates that oxidative brain damage is a previously unrecognized hallmark feature of murine RTT, and suggests that Mecp2 is involved in the protection of the brain from oxidative stress. Oxidative damage is demonstrated in the brain, and more specifically in the neurons, of Mecp2 mutant mouse models. A direct evidence between enhanced oxidative stress and Mecp2 deficiency is provided. Oxidative damage precedes the behavioral abnormalities in Mecp2 mutant mice. Mecp2 is likely involved in the protection of the brain from oxidative stress.
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92
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Inflammatory lung disease in Rett syndrome. Mediators Inflamm 2014; 2014:560120. [PMID: 24757286 PMCID: PMC3976920 DOI: 10.1155/2014/560120] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Revised: 01/06/2014] [Accepted: 01/14/2014] [Indexed: 12/30/2022] Open
Abstract
Rett syndrome (RTT) is a pervasive neurodevelopmental disorder mainly linked to mutations in the gene encoding the methyl-CpG-binding protein 2 (MeCP2). Respiratory dysfunction, historically credited to brainstem immaturity, represents a major challenge in RTT. Our aim was to characterize the relationships between pulmonary gas exchange abnormality (GEA), upper airway obstruction, and redox status in patients with typical RTT (n = 228) and to examine lung histology in a Mecp2-null mouse model of the disease. GEA was detectable in ~80% (184/228) of patients versus ~18% of healthy controls, with “high” (39.8%) and “low” (34.8%) patterns dominating over “mixed” (19.6%) and “simple mismatch” (5.9%) types. Increased plasma levels of non-protein-bound iron (NPBI), F2-isoprostanes (F2-IsoPs), intraerythrocyte NPBI (IE-NPBI), and reduced and oxidized glutathione (i.e., GSH and GSSG) were evidenced in RTT with consequently decreased GSH/GSSG ratios. Apnea frequency/severity was positively correlated with IE-NPBI, F2-IsoPs, and GSSG and negatively with GSH/GSSG ratio. A diffuse inflammatory infiltrate of the terminal bronchioles and alveoli was evidenced in half of the examined Mecp2-mutant mice, well fitting with the radiological findings previously observed in RTT patients. Our findings indicate that GEA is a key feature of RTT and that terminal bronchioles are a likely major target of the disease.
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93
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Abstract
Rett syndrome (RTT) is a severe and progressive neurological disorder, which mainly affects young females. Mutations of the methyl-CpG binding protein 2 (MECP2) gene are the most prevalent cause of classical RTT cases. MECP2 mutations or altered expression are also associated with a spectrum of neurodevelopmental disorders such as autism spectrum disorders with recent links to fetal alcohol spectrum disorders. Collectively, MeCP2 relation to these neurodevelopmental disorders highlights the importance of understanding the molecular mechanisms by which MeCP2 impacts brain development, mental conditions, and compromised brain function. Since MECP2 mutations were discovered to be the primary cause of RTT, a significant progress has been made in the MeCP2 research, with respect to the expression, function and regulation of MeCP2 in the brain and its contribution in RTT pathogenesis. To date, there have been intensive efforts in designing effective therapeutic strategies for RTT benefiting from mouse models and cells collected from RTT patients. Despite significant progress in MeCP2 research over the last few decades, there is still a knowledge gap between the in vitro and in vivo research findings and translating these findings into effective therapeutic interventions in human RTT patients. In this review, we will provide a synopsis of Rett syndrome as a severe neurological disorder and will discuss the role of MeCP2 in RTT pathophysiology.
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94
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Bissonnette JM, Schaevitz LR, Knopp SJ, Zhou Z. Respiratory phenotypes are distinctly affected in mice with common Rett syndrome mutations MeCP2 T158A and R168X. Neuroscience 2014; 267:166-76. [PMID: 24626160 DOI: 10.1016/j.neuroscience.2014.02.043] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 02/25/2014] [Accepted: 02/26/2014] [Indexed: 12/16/2022]
Abstract
Respiratory disturbances are a primary phenotype of the neurological disorder, Rett syndrome (RTT), caused by mutations in the X-linked gene encoding methyl-CpG-binding protein 2 (MeCP2). Mouse models generated with null mutations in Mecp2 mimic respiratory abnormalities in RTT girls. Large deletions, however, are seen in only ∼10% of affected human individuals. Here we characterized respiration in heterozygous females from two mouse models that genetically mimic common RTT point mutations, a missense mutation T158A (Mecp2(T158A/)(+)) or a nonsense mutation R168X (Mecp2(R168X/+)). MeCP2 T158A shows decreased binding to methylated DNA, while MeCP2 R168X retains the capacity to bind methylated DNA but lacks the ability to recruit complexes required for transcriptional repression. We found that both Mecp2(T158A/+) and Mecp2(R168X/+) heterozygotes display augmented hypoxic ventilatory responses and depressed hypercapnic responses, compared to wild-type controls. Interestingly, the incidence of apnea was much greater in Mecp2(R168X/+) heterozygotes, 189 per hour, than Mecp2(T158A/+) heterozygotes, 41 per hour. These results demonstrate that different RTT mutations lead to distinct respiratory phenotypes, suggesting that characterization of the respiratory phenotype may reveal functional differences between MeCP2 mutations and provide insights into the pathophysiology of RTT.
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Affiliation(s)
- J M Bissonnette
- Department of Obstetrics & Gynecology, Oregon Health & Science University, Portland, OR, USA; Department of Cell and Developmental Biology, Oregon Health & Science University, Portland, OR, USA.
| | - L R Schaevitz
- Department of Biology, Tufts University, Medford, MA 02155, USA
| | - S J Knopp
- Department of Obstetrics & Gynecology, Oregon Health & Science University, Portland, OR, USA
| | - Z Zhou
- Department of Genetics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
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95
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When norepinephrine becomes a driver of breathing irregularities: how intermittent hypoxia fundamentally alters the modulatory response of the respiratory network. J Neurosci 2014; 34:36-50. [PMID: 24381266 DOI: 10.1523/jneurosci.3644-12.2014] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Neuronal networks are endogenously modulated by aminergic and peptidergic substances. These modulatory processes are critical for maintaining normal activity and adapting networks to changes in metabolic, behavioral, and environmental conditions. However, disturbances in neuromodulation have also been associated with pathologies. Using whole animals (in vivo) and functional brainstem slices (in vitro) from mice, we demonstrate that exposure to acute intermittent hypoxia (AIH) leads to fundamental changes in the neuromodulatory response of the respiratory network located within the preBötzinger complex (preBötC), an area critical for breathing. Norepinephrine, which normally regularizes respiratory activity, renders respiratory activity irregular after AIH. Respiratory irregularities are caused both in vitro and in vivo by AIH, which increases synaptic inhibition within the preBötC when norepinephrine is endogenously or exogenously increased. These irregularities are prevented by blocking synaptic inhibition before AIH. However, regular breathing cannot be reestablished if synaptic inhibition is blocked after AIH. We conclude that subtle changes in synaptic transmission can have dramatic consequences at the network level as endogenously released neuromodulators that are normally adaptive become the drivers of irregularity. Moreover, irregularities in the preBötC result in irregularities in the motor output in vivo and in incomplete transmission of inspiratory activity to the hypoglossus motor nucleus. Our finding has basic science implications for understanding network functions in general, and it may be clinically relevant for understanding pathological disturbances associated with hypoxic episodes such as those associated with myocardial infarcts, obstructive sleep apneas, apneas of prematurity, Rett syndrome, and sudden infant death syndrome.
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96
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Ramirez JM. The integrative role of the sigh in psychology, physiology, pathology, and neurobiology. PROGRESS IN BRAIN RESEARCH 2014; 209:91-129. [PMID: 24746045 DOI: 10.1016/b978-0-444-63274-6.00006-0] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
"Sighs, tears, grief, distress" expresses Johann Sebastian Bach in a musical example for the relationship between sighs and deep emotions. This review explores the neurobiological basis of the sigh and its relationship with psychology, physiology, and pathology. Sighs monitor changes in brain states, induce arousal, and reset breathing variability. These behavioral roles homeostatically regulate breathing stability under physiological and pathological conditions. Sighs evoked in hypoxia evoke arousal and thereby become critical for survival. Hypoarousal and failure to sigh have been associated with sudden infant death syndrome. Increased breathing irregularity may provoke excessive sighing and hyperarousal, a behavioral sequence that may play a role in panic disorders. Essential for generating sighs and breathing is the pre-Bötzinger complex. Modulatory and synaptic interactions within this local network and between networks located in the brainstem, cerebellum, cortex, hypothalamus, amygdala, and the periaqueductal gray may govern the relationships between physiology, psychology, and pathology. Unraveling these circuits will lead to a better understanding of how we balance emotions and how emotions become pathological.
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Affiliation(s)
- Jan-Marino Ramirez
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA; Department of Neurological Surgery, University of Washington, Seattle, WA, USA.
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97
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Buchovecky CM, Hill MG, Borkey JM, Kyle SM, Justice MJ. Evaluation of Rett Syndrome Symptom Improvement by Metabolic Modulators in Mecp2-Mutant Mice. ACTA ACUST UNITED AC 2013; 3:187-204. [PMID: 26069093 DOI: 10.1002/9780470942390.mo130157] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Mouse models recapitulate many symptoms of Rett Syndrome, an X-linked disorder caused by mutations in methyl-CpG-binding protein 2 (MECP2). The study of Mecp2-null male mice has provided insight into pathogenesis of the disorder-most recently, dysregulation of cholesterol and lipid metabolism. Perisymptomatic treatment with statin drugs successfully mitigates the effects of this metabolic syndrome, increases longevity, and improves motor function. Described here is a metabolic drug screening protocol and timeline for symptom evaluation in Mecp2-mutant mice. Specifically, mice are treated twice weekly with a compound of interest alongside subjective health assessments, bi-weekly body composition measurements, and blood chemistries. Throughout treatment, behavioral phenotyping tests are carried out at specific time points. This protocol is highly adaptable to other neurological diseases; however, the time for completion depends on the specific mutant model under study. The protocol highlights the use of techniques described in several different Current Protocols in Mouse Biology articles to carry out testing in a preclinical model. Curr. Protoc. Mouse Biol. 3:187-204 © 2013 by John Wiley & Sons, Inc.
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Affiliation(s)
- Christie M Buchovecky
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
| | - Misty G Hill
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
| | - Jennifer M Borkey
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
| | - Stephanie M Kyle
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
| | - Monica J Justice
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
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98
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Clinical challenges to ventilatory control. Respir Physiol Neurobiol 2013; 189:211-2. [PMID: 24056024 DOI: 10.1016/j.resp.2013.09.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Levitt ES, Hunnicutt BJ, Knopp SJ, Williams JT, Bissonnette JM. A selective 5-HT1a receptor agonist improves respiration in a mouse model of Rett syndrome. J Appl Physiol (1985) 2013; 115:1626-33. [PMID: 24092697 DOI: 10.1152/japplphysiol.00889.2013] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Rett syndrome is a neurological disorder caused by loss of function mutations in the gene that encodes the DNA binding protein methyl-CpG-binding protein 2 (Mecp2). A prominent feature of the syndrome is disturbances in respiration characterized by frequent apnea and an irregular interbreath cycle. 8-Hydroxy-2-dipropylaminotetralin has been shown to positively modulate these disturbances (Abdala AP, Dutschmann M, Bissonnette JM, Paton JF, Proc Natl Acad Sci U S A 107: 18208-18213, 2010), but the mode of action is not understood. Here we show that the selective 5-HT1a biased agonist 3-chloro-4-fluorophenyl-(4-fluoro-4-{[(5-methylpyrimidin-2-ylmethyl)-amino]-methyl}-piperidin-1-yl)-methanone (F15599) decreases apnea and corrects irregularity in both heterozygous Mecp2-deficient female and in Mecp2 null male mice. In whole cell voltage-clamp recordings from dorsal raphe neurons, F15599 potently induced an outward current, which was blocked by barium, reversed at the potassium equilibrium potential, and was antagonized by the 5-HT1a antagonist WAY100135. This is consistent with somatodendritic 5-HT1a receptor-mediated activation of G protein-coupled inwardly rectifying potassium channels (GIRK). In contrast, F15599 did not activate 5-HT1b/d receptors that mediate inhibition of glutamate release from terminals in the nucleus accumbens by a presynaptic mechanism. Thus F15599 activated somatodendritic 5-HT1a autoreceptors, but not axonal 5-HT1b/d receptors. In unanesthetized Mecp2-deficient heterozygous female mice, F15599 reduced apnea in a dose-dependent manner with maximal effect of 74.5 ± 6.9% at 0.1 mg/kg and improved breath irrregularity. Similarly, in Mecp2 null male mice, apnea was reduced by 62 ± 6.6% at 0.25 mg/kg, and breathing became regular. The results indicate respiration is improved with a 5-HT1a agonist that activates GIRK channels without affecting neurotransmitter release.
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Affiliation(s)
- Erica S Levitt
- Vollum Institute, Oregon Health and Science University, Portland, Oregon
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