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Caudal D, François V, Lafoux A, Ledevin M, Anegon I, Le Guiner C, Larcher T, Huchet C. Characterization of brain dystrophins absence and impact in dystrophin-deficient Dmdmdx rat model. PLoS One 2020; 15:e0230083. [PMID: 32160266 PMCID: PMC7065776 DOI: 10.1371/journal.pone.0230083] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 02/20/2020] [Indexed: 12/27/2022] Open
Abstract
Duchenne Muscular Dystrophy (DMD) is a severe muscle-wasting disease caused by mutations in the DMD gene encoding dystrophin, expressed mainly in muscles but also in other tissues like retina and brain. Non-progressing cognitive dysfunction occurs in 20 to 50% of DMD patients. Furthermore, loss of expression of the Dp427 dystrophin isoform in the brain of mdx mice, the most used animal model of DMD, leads to behavioral deficits thought to be linked to insufficiencies in synaptogenesis and channel clustering at synapses. Mdx mice where the locomotor phenotype is mild also display a high and maladaptive response to stress. Recently, we generated Dmdmdx rats carrying an out-of frame mutation in exon 23 of the DMD gene and exhibiting a skeletal and cardiac muscle phenotype similar to DMD patients. In order to evaluate the impact of dystrophin loss on behavior, we explored locomotion parameters as well as anhedonia, anxiety and response to stress, in Dmdmdx rats aged from 1.5 to 7 months, in comparison to wild-type (WT) littermates. Pattern of dystrophin expression in the brain of WT and Dmdmdx rats was characterized by western-blot analyses and immunohistochemistry. We showed that dystrophin-deficient Dmdmdx rats displayed motor deficits in the beam test, without association with depressive or anxiety-like phenotype. However, Dmdmdx rats exhibited a strong response to restraint-induced stress, with a large increase in freezings frequency and duration, suggesting an alteration in a functional circuit including the amygdala. In brain, large dystrophin isoform Dp427 was not expressed in mutant animals. Dmdmdx rat is therefore a good animal model for preclinical evaluations of new treatments for DMD but care must be taken with their responses to mild stress.
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Affiliation(s)
- Dorian Caudal
- Therassay Platform, CAPACITES, Université de Nantes, Nantes, France
- * E-mail:
| | - Virginie François
- Nantes Gene Therapy Laboratory, Université de Nantes, INSERM UMR 1089, Nantes, France
| | - Aude Lafoux
- Therassay Platform, CAPACITES, Université de Nantes, Nantes, France
| | | | | | - Caroline Le Guiner
- Nantes Gene Therapy Laboratory, Université de Nantes, INSERM UMR 1089, Nantes, France
| | | | - Corinne Huchet
- Therassay Platform, CAPACITES, Université de Nantes, Nantes, France
- Nantes Gene Therapy Laboratory, Université de Nantes, INSERM UMR 1089, Nantes, France
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Cognitive impairment appears progressive in the mdx mouse. Neuromuscul Disord 2020; 30:368-388. [PMID: 32360405 PMCID: PMC7306157 DOI: 10.1016/j.nmd.2020.02.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 02/24/2020] [Accepted: 02/25/2020] [Indexed: 11/22/2022]
Abstract
Duchenne muscular dystrophy (DMD) is an X-linked recessive muscle wasting disease caused by mutations in the DMD gene, which encodes the large cytoskeletal protein dystrophin. Approximately one-third of DMD patient's exhibit cognitive problems yet it is unknown if cognitive impairments worsen with age. The mdx mouse model is deficient in dystrophin demonstrates cognitive abnormalities, but no studies have investigated this longitudinally. We assessed the consequences of dystrophin deficiency on brain morphology and cognition in male mdx mice. We utilised non-invasive methods to monitor CNS pathology with an aim to identify changes longitudinally (between 4 and 18 months old) which could be used as outcome measures. MRI identified a total brain volume (TBV) increase in control mice with ageing (p < 0.05); but the mdx mice TBV increased significantly more (p < 0.01). Voxel-based morphometry (VBM) identified decreases in grey matter volume, particularly in the hippocampus of the mdx brain, most noticeable from 12 months onwards, as were enlarged lateral ventricles in mdx mice. The caudate putamen of older mdx mice showed increases in T2- relaxometry which may be considered as evidence of increased water content. Hippocampal spatial learning and memory was decreased in mdx mice, particularly long-term memory, which progressively worsened with age. The novel object recognition (NOR) task highlighted elevated anxiety-related behaviour in older mdx mice. Our studies suggest that dystrophin deficiency causes a progressive cognitive impairment in mice (compared to ageing control mice), becoming evident at late disease stages, and may explain why progressive CNS symptoms are not obvious in DMD patients.
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Abstract
Duchenne muscular dystrophy is a highly progressive neuromuscular disorder caused by primary abnormalities in the Dmd gene encoding the membrane cytoskeletal protein dystrophin. Dystrophinopathies are multi-systems disorders that are characterized by severe skeletal muscle wasting, with loss of independent ambulation in the early teenage years, followed by cardio-respiratory complications and premature death. Nonprogressive cognitive impairments are estimated to affect approximately one-third of dystrophic children. To identify the molecular mechanisms behind the impaired brain function in dystrophinopathy, liquid chromatography-based mass spectrometry offers an unbiased and technology-driven approach. In this chapter, we give a detailed description of a label-free mass spectrometric method to investigate proteome-wide changes in the dystrophin-deficient brain from a genetic mouse model of Duchenne muscular dystrophy.
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Affiliation(s)
- Sandra Murphy
- Department of Biology, Maynooth University, National University of Ireland Maynooth, Callan Building, North Campus, Maynooth, Co. Kildare, Ireland
| | - Kay Ohlendieck
- Department of Biology, Maynooth University, National University of Ireland Maynooth, Callan Building, North Campus, Maynooth, Co. Kildare, Ireland.
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Timing and localization of human dystrophin isoform expression provide insights into the cognitive phenotype of Duchenne muscular dystrophy. Sci Rep 2017; 7:12575. [PMID: 28974727 PMCID: PMC5626779 DOI: 10.1038/s41598-017-12981-5] [Citation(s) in RCA: 106] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 09/13/2017] [Indexed: 01/14/2023] Open
Abstract
Duchenne muscular dystrophy (DMD) is a muscular dystrophy with high incidence of learning and behavioural problems and is associated with neurodevelopmental disorders. To gain more insights into the role of dystrophin in this cognitive phenotype, we performed a comprehensive analysis of the expression patterns of dystrophin isoforms across human brain development, using unique transcriptomic data from Allen Human Brain and BrainSpan atlases. Dystrophin isoforms show large changes in expression through life with pronounced differences between the foetal and adult human brain. The Dp140 isoform was expressed in the cerebral cortex only in foetal life stages, while in the cerebellum it was also expressed postnatally. The Purkinje isoform Dp427p was virtually absent. The expression of dystrophin isoforms was significantly associated with genes implicated in neurodevelopmental disorders, like autism spectrum disorders or attention-deficit hyper-activity disorders, which are known to be associated to DMD. We also identified relevant functional associations of the different isoforms, like an association with axon guidance or neuron differentiation during early development. Our results point to the crucial role of several dystrophin isoforms in the development and function of the human brain.
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Alexander MS, Gasperini MJ, Tsai PT, Gibbs DE, Spinazzola JM, Marshall JL, Feyder MJ, Pletcher MT, Chekler ELP, Morris CA, Sahin M, Harms JF, Schmidt CJ, Kleiman RJ, Kunkel LM. Reversal of neurobehavioral social deficits in dystrophic mice using inhibitors of phosphodiesterases PDE5A and PDE9A. Transl Psychiatry 2016; 6:e901. [PMID: 27676442 PMCID: PMC5048211 DOI: 10.1038/tp.2016.174] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 07/18/2016] [Indexed: 12/31/2022] Open
Abstract
Duchenne muscular dystrophy is caused by mutations in the DYSTROPHIN gene. Although primarily associated with muscle wasting, a significant portion of patients (approximately 25%) are also diagnosed with autism spectrum disorder. We describe social behavioral deficits in dystrophin-deficient mice and present evidence of cerebellar deficits in cGMP production. We demonstrate therapeutic potential for selective inhibitors of the cGMP-specific PDE5A and PDE9A enzymes to restore social behaviors in dystrophin-deficient mice.
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Affiliation(s)
- M S Alexander
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA, USA
- Departments of Pediatrics and Genetics, Harvard Medical School, Boston, MA, USA
- The Stem Cell Program, Boston Children's Hospital, Boston, MA, USA
| | - M J Gasperini
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA, USA
| | - P T Tsai
- The F.M. Kirby Neurobiology Center, Translational Neuroscience Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - D E Gibbs
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA, USA
| | - J M Spinazzola
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA, USA
- Departments of Pediatrics and Genetics, Harvard Medical School, Boston, MA, USA
| | - J L Marshall
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA, USA
| | - M J Feyder
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA, USA
| | - M T Pletcher
- Rare Disease Research Unit, Pfizer, Cambridge, MA, USA
| | - E L P Chekler
- Rare Disease Research Unit, Pfizer, Cambridge, MA, USA
| | - C A Morris
- Rare Disease Research Unit, Pfizer, Cambridge, MA, USA
| | - M Sahin
- The F.M. Kirby Neurobiology Center, Translational Neuroscience Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - J F Harms
- Neuroscience Research Unit, Pfizer Global Research and Development, Cambridge, MA, USA
| | - C J Schmidt
- Neuroscience Research Unit, Pfizer Global Research and Development, Cambridge, MA, USA
| | - R J Kleiman
- The F.M. Kirby Neurobiology Center, Translational Neuroscience Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - L M Kunkel
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA, USA
- Departments of Pediatrics and Genetics, Harvard Medical School, Boston, MA, USA
- The Stem Cell Program, Boston Children's Hospital, Boston, MA, USA
- The Manton Center for Orphan Diseases, Boston, MA, USA
- Harvard Stem Cell Institute, Cambridge, MA, USA
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Hendriksen RGF, Schipper S, Hoogland G, Schijns OEMG, Dings JTA, Aalbers MW, Vles JSH. Dystrophin Distribution and Expression in Human and Experimental Temporal Lobe Epilepsy. Front Cell Neurosci 2016; 10:174. [PMID: 27458343 PMCID: PMC4937016 DOI: 10.3389/fncel.2016.00174] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 06/21/2016] [Indexed: 01/17/2023] Open
Abstract
OBJECTIVE Dystrophin is part of a protein complex that connects the cytoskeleton to the extracellular matrix. In addition to its role in muscle tissue, it functions as an anchoring protein within the central nervous system such as in hippocampus and cerebellum. Its presence in the latter regions is illustrated by the cognitive problems seen in Duchenne Muscular Dystrophy (DMD). Since epilepsy is also supposed to constitute a comorbidity of DMD, it is hypothesized that dystrophin plays a role in neuronal excitability. Here, we aimed to study brain dystrophin distribution and expression in both, human and experimental temporal lobe epilepsy (TLE). METHOD Regional and cellular dystrophin distribution was evaluated in both human and rat hippocampi and in rat cerebellar tissue by immunofluorescent colocalization with neuronal (NeuN and calbindin) and glial (GFAP) markers. In addition, hippocampal dystrophin levels were estimated by Western blot analysis in biopsies from TLE patients, post-mortem controls, amygdala kindled (AK)-, and control rats. RESULTS Dystrophin was expressed in all hippocampal pyramidal subfields and in the molecular-, Purkinje-, and granular cell layer of the cerebellum. In these regions it colocalized with GFAP, suggesting expression in astrocytes such as Bergmann glia (BG) and velate protoplasmic astrocytes. In rat hippocampus and cerebellum there were neither differences in dystrophin positive cell types, nor in the regional dystrophin distribution between AK and control animals. Quantitatively, hippocampal full-length dystrophin (Dp427) levels were about 60% higher in human TLE patients than in post-mortem controls (p < 0.05), whereas the level of the shorter Dp71 isoform did not differ. In contrast, AK animals showed similar dystrophin levels as controls. CONCLUSION Dystrophin is ubiquitously expressed by astrocytes in the human and rat hippocampus and in the rat cerebellum. Hippocampal full-length dystrophin (Dp427) levels are upregulated in human TLE, but not in AK rats, possibly indicating a compensatory mechanism in the chronic epileptic human brain.
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Affiliation(s)
- Ruben G F Hendriksen
- Department of Neurology, Maastricht University Medical Centre Maastricht, Netherlands
| | - Sandra Schipper
- Department of Neurology, Maastricht University Medical CentreMaastricht, Netherlands; School for Mental Health and Neuroscience, Maastricht UniversityMaastricht, Netherlands
| | - Govert Hoogland
- School for Mental Health and Neuroscience, Maastricht UniversityMaastricht, Netherlands; Department of Neurosurgery, Maastricht University Medical CentreMaastricht, Netherlands
| | - Olaf E M G Schijns
- Department of Neurosurgery, Maastricht University Medical Centre Maastricht, Netherlands
| | - Jim T A Dings
- Department of Neurosurgery, Maastricht University Medical Centre Maastricht, Netherlands
| | - Marlien W Aalbers
- Department of Neurosurgery, Groningen University Medical Centre Groningen, Netherlands
| | - Johan S H Vles
- Department of Neurology, Maastricht University Medical Centre Maastricht, Netherlands
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Hepatocyte Growth Factor and Satellite Cell Activation. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 900:1-25. [PMID: 27003394 DOI: 10.1007/978-3-319-27511-6_1] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Satellite cells are the "currency" for the muscle growth that is critical to meat production in many species, as well as to phenotypic distinctions in development at the level of species or taxa, and for human muscle growth, function and regeneration. Careful research on the activation and behaviour of satellite cells, the stem cells in skeletal muscle, including cross-species comparisons, has potential to reveal the mechanisms underlying pathological conditions in animals and humans, and to anticipate implications of development, evolution and environmental change on muscle function and animal performance.
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Schara U, Busse M, Timmann D, Gerwig M. Cerebellar-dependent associative learning is preserved in Duchenne muscular dystrophy: a study using delay eyeblink conditioning. PLoS One 2015; 10:e0126528. [PMID: 25973604 PMCID: PMC4431835 DOI: 10.1371/journal.pone.0126528] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 04/03/2015] [Indexed: 02/03/2023] Open
Abstract
Objective Besides progressive muscle weakness cognitive deficits have been reported in patients with Duchenne muscular dystrophy (DMD). Cerebellar dysfunction has been proposed to explain cognitive deficits at least in part. In animal models of DMD disturbed Purkinje cell function has been shown following loss of dystrophin. Furthermore there is increasing evidence that the lateral cerebellum contributes to cognitive processing. In the present study cerebellar-dependent delay eyeblink conditioning, a form of associative learning, was used to assess cerebellar function in DMD children. Methods Delay eyeblink conditioning was examined in eight genetically defined male patients with DMD and in ten age-matched control subjects. Acquisition, timing and extinction of conditioned eyeblink responses (CR) were assessed during a single conditioning session. Results Both groups showed a significant increase of CRs during the course of learning (block effect p < 0.001). CR acquisition was not impaired in DMD patients (mean total CR incidence 37.4 ± 17.6%) as compared to control subjects (36.2 ± 17.3%; group effect p = 0.89; group by block effect p = 0.38; ANOVA with repeated measures). In addition, CR timing and extinction was not different from controls. Conclusions Delay eyeblink conditioning was preserved in the present DMD patients. Because eyeblink conditioning depends on the integrity of the intermediate cerebellum, this older part of the cerebellum may be relatively preserved in DMD. The present findings agree with animal model data showing that the newer, lateral cerebellum is primarily affected in DMD.
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Affiliation(s)
- Ulrike Schara
- Department of Neuropediatrics, Developmental Neurology and Social Pediatrics,University of Duisburg-Essen, Essen, Germany
| | - Melanie Busse
- Department of Neuropediatrics, Developmental Neurology and Social Pediatrics,University of Duisburg-Essen, Essen, Germany
| | - Dagmar Timmann
- Department of Neurology, University of Duisburg-Essen, Essen, Germany
| | - Marcus Gerwig
- Department of Neurology, University of Duisburg-Essen, Essen, Germany
- * E-mail:
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Arancillo M, White JJ, Lin T, Stay TL, Sillitoe RV. In vivo analysis of Purkinje cell firing properties during postnatal mouse development. J Neurophysiol 2014; 113:578-91. [PMID: 25355961 DOI: 10.1152/jn.00586.2014] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Purkinje cell activity is essential for controlling motor behavior. During motor behavior Purkinje cells fire two types of action potentials: simple spikes that are generated intrinsically and complex spikes that are induced by climbing fiber inputs. Although the functions of these spikes are becoming clear, how they are established is still poorly understood. Here, we used in vivo electrophysiology approaches conducted in anesthetized and awake mice to record Purkinje cell activity starting from the second postnatal week of development through to adulthood. We found that the rate of complex spike firing increases sharply at 3 wk of age whereas the rate of simple spike firing gradually increases until 4 wk of age. We also found that compared with adult, the pattern of simple spike firing during development is more irregular as the cells tend to fire in bursts that are interrupted by long pauses. The regularity in simple spike firing only reached maturity at 4 wk of age. In contrast, the adult complex spike pattern was already evident by the second week of life, remaining consistent across all ages. Analyses of Purkinje cells in alert behaving mice suggested that the adult patterns are attained more than a week after the completion of key morphogenetic processes such as migration, lamination, and foliation. Purkinje cell activity is therefore dynamically sculpted throughout postnatal development, traversing several critical events that are required for circuit formation. Overall, we show that simple spike and complex spike firing develop with unique developmental trajectories.
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Affiliation(s)
- Marife Arancillo
- Department of Pathology and Immunology, Department of Neuroscience, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital, Houston, Texas
| | - Joshua J White
- Department of Pathology and Immunology, Department of Neuroscience, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital, Houston, Texas
| | - Tao Lin
- Department of Pathology and Immunology, Department of Neuroscience, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital, Houston, Texas
| | - Trace L Stay
- Department of Pathology and Immunology, Department of Neuroscience, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital, Houston, Texas
| | - Roy V Sillitoe
- Department of Pathology and Immunology, Department of Neuroscience, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital, Houston, Texas
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Acetylcholine, GABA and neuronal networks: a working hypothesis for compensations in the dystrophic brain. Brain Res Bull 2014; 110:1-13. [PMID: 25445612 DOI: 10.1016/j.brainresbull.2014.10.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Revised: 10/02/2014] [Accepted: 10/06/2014] [Indexed: 11/22/2022]
Abstract
Duchenne muscular dystrophy (DMD), a genetic disease arising from a mutation in the dystrophin gene, is characterized by muscle failure and is often associated with cognitive deficits. Studies of the dystrophic brain on the murine mdx model of DMD provide evidence of morphological and functional alterations in the central nervous system (CNS) possibly compatible with the cognitive impairment seen in DMD. However, while some of the alterations reported are a direct consequence of the absence of dystrophin, others seem to be associated only indirectly. In this review we reevaluate the literature in order to formulate a possible explanation for the cognitive impairments associated with DMD. We present a working hypothesis, demonstrated as an integrated neuronal network model, according to which within the cascade of events leading to cognitive impairments there are compensatory mechanisms aimed to maintain functional stability via perpetual adjustments of excitatory and inhibitory components. Such ongoing compensatory response creates continuous perturbations that disrupt neuronal functionality in terms of network efficiency. We have theorized that in this process acetylcholine and network oscillations play a central role. A better understating of these mechanisms could provide a useful diagnostic index of the disease's progression and, perhaps, the correct counterbalance of this process might help to prevent deterioration of the CNS in DMD. Furthermore, the involvement of compensatory mechanisms in the CNS could be extended beyond DMD and possibly help to clarify other physio-pathological processes of the CNS.
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Snow WM, Anderson JE, Fry M. Regional and genotypic differences in intrinsic electrophysiological properties of cerebellar Purkinje neurons from wild-type and dystrophin-deficient mdx mice. Neurobiol Learn Mem 2014; 107:19-31. [DOI: 10.1016/j.nlm.2013.10.017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Revised: 10/10/2013] [Accepted: 10/25/2013] [Indexed: 10/26/2022]
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Janke A, Upadhaya R, Snow WM, Anderson JE. A new look at cytoskeletal NOS-1 and β-dystroglycan changes in developing muscle and brain in control and mdx dystrophic mice. Dev Dyn 2013; 242:1369-81. [PMID: 23940011 DOI: 10.1002/dvdy.24031] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 07/17/2013] [Accepted: 07/25/2013] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Loss of dystrophin profoundly affects muscle function and cognition. Changes in the dystrophin-glycoprotein complex (DGC) including disruption of nitric oxide synthase (NOS-1) may result from loss of dystrophin or secondarily after muscle damage. Disruptions in NOS-1 and beta-dystroglycan (bDG) were examined in developing diaphragm, quadriceps, and two brain regions between control and mdx mice at embryonic day E18 and postnatal days P1, P10, and P28. Age-dependent differential muscle loading allowed us to test the hypothesis that DGC changes are dependent on muscle use. RESULTS Muscle development, including loss of central nucleation and the localization of NOS-1 and bDG, was earlier in diaphragm than quadriceps; these features were differentially disrupted in dystrophic muscles. The NOS-1/bDG ratio, an index of DGC stability, was higher in dystrophic diaphragm (P10-P28) and quadriceps (P28) than controls. There were also distinct regional differences in NOS-1 and bDG in brain tissues with age and strain. NOS-1 increased with age in control forebrain and cerebellum, and in mdx cerebellum; NOS-1 and bDG were higher in control than mdx mouse forebrain. CONCLUSIONS Important developmental changes in structure and muscle DGC preceded the hallmarks of dystrophy, and are consistent with the impact of muscle-specific differential loading during maturation.
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Affiliation(s)
- Alyssa Janke
- Faculty of Science, Department of Biological Sciences, Faculty of Medicine, University of Manitoba, Winnipeg, Canada
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