101
|
Cardiac electrophysiological characteristics of the mdx 5cv mouse model of Duchenne muscular dystrophy. J Interv Card Electrophysiol 2007; 20:1-7. [DOI: 10.1007/s10840-007-9168-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2007] [Accepted: 09/27/2007] [Indexed: 10/22/2022]
|
102
|
Deng S, Kulle B, Hosseini M, Schlüter G, Hasenfuss G, Wojnowski L, Schmidt A. Dystrophin-deficiency increases the susceptibility to doxorubicin-induced cardiotoxicity. Eur J Heart Fail 2007; 9:986-94. [PMID: 17888722 DOI: 10.1016/j.ejheart.2007.07.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2006] [Revised: 06/15/2007] [Accepted: 07/17/2007] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND AND AIM The clinical use of doxorubicin (DOX) and other anthracyclines is limited by a dosage-dependent cardiotoxicity, which can lead to cardiomyopathy. The role of the individual genetic makeup in this disorder is poorly understood. Alterations in genes encoding cardiac cytoskeleton or sarcolemma proteins may increase the susceptibility to doxorubicin-related cardiotoxicity. METHODS Female dystrophin-deficient mice (MDX) and age-matched wild-type mice underwent chronic treatment with doxorubicin. Cardiac function and tissue damage were assessed by echocardiography and histopathology, respectively. Gene expression changes were investigated using microarrays. RESULTS DOX treatment resulted in mortality, cardiac insufficiency, and cardiac interstitial fibrosis. These alterations were more pronounced in DOX-treated MDX mice than in DOX-treated wild-type mice. Changes in gene expression were more numerous in MDX mice, including genes involved in cell adhesion, oxidative stress, cytoskeleton organization, inflammatory and immune response and cell death. CONCLUSIONS Dystrophin deficiency facilitates the development and progression of doxorubicin-induced cardiac injury. The underlying mechanisms may involve changes in cell adhesion, in cytoskeleton, as well as in inflammatory and immune responses. Genetic variants of cytoskeletal proteins in humans may affect the individual susceptibility to doxorubicin. Cardiotoxic drugs may accelerate the manifestation of pre-clinical cardiomyopathies caused by deficiencies in cytoskeletal or sarcolemma proteins.
Collapse
Affiliation(s)
- Shiwei Deng
- Department of Pharmacology, Johannes Gutenberg University, 55101 Mainz, Germany
| | | | | | | | | | | | | |
Collapse
|
103
|
Duboc D, Meune C, Pierre B, Wahbi K, Eymard B, Toutain A, Berard C, Vaksmann G, Weber S, Bécane HM. Perindopril preventive treatment on mortality in Duchenne muscular dystrophy: 10 years' follow-up. Am Heart J 2007; 154:596-602. [PMID: 17719312 DOI: 10.1016/j.ahj.2007.05.014] [Citation(s) in RCA: 218] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2007] [Accepted: 05/14/2007] [Indexed: 12/16/2022]
Abstract
BACKGROUND Duchenne muscular dystrophy (DMD), an X-linked disorder due to lack of dystrophin, is associated with muscle weakness and myocardial dysfunction. Although preliminary data support the efficacy of angiotensin-converting enzyme inhibitors on left ventricular (LV) function, our aim was to examine the long-term impact of a preventive treatment with perindopril on mortality in children with DMD. METHODS Patients with DMD between the ages of 9.5 and 13 years presenting with normal LV ejection fraction were included in this prospective study. They were randomly assigned for 3 years to perindopril, 2 to 4 mg (group 1), or placebo (group 2) in a double-blind protocol, followed by open-label treatment with perindopril for up to 10 years. Survival rate at 10 years in each group is reported. RESULTS There were 28 patients assigned to group 1 and 29 to group 2. Baseline characteristics were similar in both groups. At the end of the 10 years' follow-up period, survival status was available for all included patients: 26 (92.9%) of 28 patients in group 1 were alive at 10 years versus 19 (65.5%) of 29 in group 2 (P = .02). Kaplan-Meier cumulative survival was significantly lower in group 2 than in group 1 (P = .013). CONCLUSION Early initiation of treatment with perindopril is associated with a lower mortality in patients with DMD with normal LV ejection fraction at study entry.
Collapse
Affiliation(s)
- Denis Duboc
- Department of Cardiology, Cochin Hospital, APHP, Paris V René Descartes University, Paris, France
| | | | | | | | | | | | | | | | | | | |
Collapse
|
104
|
Duboc D, Meune C, Pierre B, Wahbi K, Eymard B, Toutain A, Berard C, Vaksmann G, Bécane HM. Perindopril preserves left ventricular function in X-linked Duchenne muscular dystrophy. Eur Heart J Suppl 2007. [DOI: 10.1093/eurheartj/sum036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
|
105
|
Xu R, Chandrasekharan K, Yoon JH, Camboni M, Martin PT. Overexpression of the cytotoxic T cell (CT) carbohydrate inhibits muscular dystrophy in the dyW mouse model of congenital muscular dystrophy 1A. THE AMERICAN JOURNAL OF PATHOLOGY 2007; 171:181-99. [PMID: 17591965 PMCID: PMC1941597 DOI: 10.2353/ajpath.2007.060927] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A number of recent studies have demonstrated therapeutic effects of transgenes on the development of muscle pathology in the mdx mouse model for Duchenne muscular dystrophy, but none have been shown also to be effective in mouse models for laminin alpha2-deficient congenital muscular dystrophy (MDC1A). Here, we show that overexpression of the cytotoxic T cell (CT) GalNAc transferase (Galgt2) is effective in inhibiting the development of muscle pathology in the dy(W) mouse model of MDC1A, much as we had previously shown in mdx animals. Embryonic overexpression of Galgt2 in skeletal muscles using transgenic mice or postnatal overexpression using adeno-associated virus both reduced the extent of muscle pathology in dy(W)/dy(W) skeletal muscle. As with mdx mice, embryonic overexpression of the Galgt2 transgene in dy(W)/dy(W) myofibers inhibited muscle growth, whereas postnatal overexpression did not. Both embryonic and postnatal overexpression of Galgt2 in dy(W)/dy(W) muscle increased the expression of agrin, a protein that, in recombinant form, has been shown to ameliorate disease, whereas laminin alpha1, another disease modifier, was not expressed. Galgt2 over-expression also stimulated the glycosylation of a gly-colipid with the CT carbohydrate, and glycolipids accounted for most of the CT-reactive material in postnatal overexpression experiments. These experiments demonstrate that Galgt2 overexpression is effective in altering disease progression in skeletal muscles of dy(W) mice and should be considered as a therapeutic target in MDC1A.
Collapse
Affiliation(s)
- Rui Xu
- Center for Gene Therapy, Columbus Children's Research Institute, Department of Pediatrics, Ohio State University College of Medicine and Public Health, Columbus, OH 43205, USA
| | | | | | | | | |
Collapse
|
106
|
Williams IA, Allen DG. The role of reactive oxygen species in the hearts of dystrophin-deficient mdx mice. Am J Physiol Heart Circ Physiol 2007; 293:H1969-77. [PMID: 17573457 DOI: 10.1152/ajpheart.00489.2007] [Citation(s) in RCA: 130] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Duchenne muscular dystrophy (DMD) is caused by deficiency of the cytoskeletal protein dystrophin. Oxidative stress is thought to contribute to the skeletal muscle damage in DMD; however, little is known about the role of oxidative damage in the pathogenesis of the heart failure that occurs in DMD patients. The dystrophin-deficient (mdx) mouse is an animal model of DMD that also lacks dystrophin. The current study investigates the role of the antioxidant N-acetylcysteine (NAC) on mdx cardiomyocyte function, Ca(2+) handling, and the cardiac inflammatory response. Treated mice received 1% NAC in their drinking water for 6 wk. NAC had no effect on wild-type (WT) mice. Immunohistochemistry experiments revealed that mdx mice had increased dihydroethidine (DHE) staining, an indicator of superoxide production; NAC-treatment reduced DHE staining in mdx hearts. NAC treatment attenuated abnormalities in mdx cardiomyocyte Ca(2+) handling. Mdx cardiomyocytes had decreased fractional shortening and decreased Ca(2+) sensitivity; NAC treatment returned mdx fractional shortening to WT values but did not affect the Ca(2+) sensitivity. Immunohistochemistry experiments revealed that mdx hearts had increased levels of collagen type III and the macrophage-specific protein, CD68; NAC-treatment returned collagen type III and CD68 expression close to WT values. Finally, mdx hearts had increased NADPH oxidase activity, suggesting it could be a possible source of increased reactive oxygen species in mdx mice. This study is the first to demonstrate that oxidative damage may be involved in the pathogenesis of the heart failure that occurs in mdx mice. Therapies designed to reduce oxidative damage might be beneficial to DMD patients with heart failure.
Collapse
Affiliation(s)
- Iwan A Williams
- Bosch Institute, School of Medical Sciences, University of Sydney F13, NSW 2006 Australia
| | | |
Collapse
|
107
|
Khairallah M, Khairallah R, Young ME, Dyck JRB, Petrof BJ, Des Rosiers C. Metabolic and signaling alterations in dystrophin-deficient hearts precede overt cardiomyopathy. J Mol Cell Cardiol 2007; 43:119-29. [PMID: 17583724 DOI: 10.1016/j.yjmcc.2007.05.015] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2007] [Revised: 04/20/2007] [Accepted: 05/14/2007] [Indexed: 01/16/2023]
Abstract
The cytoskeletal protein dystrophin has been implicated in hereditary and acquired forms of cardiomyopathy. However, much remains to be learned about the role of dystrophin in the heart. We hypothesized that the dystrophin-deficient heart displays early alterations in energy metabolism that precede overt cardiomyopathy. We evaluated the metabolic and functional phenotype of dystrophin-deficient mdx mouse hearts at 10-12 weeks, when no major histological or echocardiographic abnormalities are reported. Ex vivo working mdx heart perfusions with stable isotopes revealed a marked shift in substrate fuel selection from fatty acids to carbohydrates associated with enhanced oxygen consumption. They also unmasked in the mdx heart: (i) compromised cardiac contractile function and efficiency, (ii) reduced cellular integrity, and (iii) exacerbated alterations in mitochondrial citric acid cycle-related parameters and in nutrient signaling pathways related to Akt. The observed shift in substrate selection cannot be explained by metabolic gene remodeling. However, mdx mice hearts showed an increased expression of the atrial natriuretic factor (anf) gene, an activator of the nitric oxide (NO)/cGMP signaling pathway and marker of cardiac remodeling, and, only as the cardiomyopathy progresses (at 25 weeks of age), an increased expression of the alpha1 subunit of soluble guanylate cyclase, which is known to negatively correlate with the activity NO/cGMP pathway. Collectively, our results highlight early metabolic and signaling alterations in the dystrophin-deficient heart, which may predispose these hearts to contractile dysfunction and sarcolemmal fragility. They also suggest the presence of a "sub-clinical" defect in the NO/cGMP pathway, which in vivo, at an early age, may be compensated by enhanced anf gene expression.
Collapse
Affiliation(s)
- Maya Khairallah
- Montreal Heart Institute and University of Montreal, 5000 Belanger St., Montreal, Quebec, Canada H1T 1C8
| | | | | | | | | | | |
Collapse
|
108
|
Li D, Wang L, Lee CW, Dawson TA, Paterson DJ. Noradrenergic cell specific gene transfer with neuronal nitric oxide synthase reduces cardiac sympathetic neurotransmission in hypertensive rats. Hypertension 2007; 50:69-74. [PMID: 17515453 DOI: 10.1161/hypertensionaha.107.088591] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Nitric oxide-cGMP pathway can inhibit cardiac norepinephrine (NE) release. Sympathetic hyper-responsiveness in hypertension may result from oxidative stress impairing this pathway. We tested the hypothesis that the gene transfer of neuronal NO synthase (nNOS) could restore sympathetic balance in the spontaneously hypertensive rat (SHR). An adenovirus (5x10(10) particles) constructed with a noradrenergic neuron-specific promoter (PRS x8) encoding nNOS (Ad.PRS-nNOS) or enhanced green fluorescence protein (Ad.PRS-eGFP) was targeted to the right atrial wall by percutaneous injection in age-matched male SHRs and Wistar-Kyoto (WKY) rats. Five days after transduction, right atria were removed, and evoked [(3)H] norephinephrine (NE) release, NOS activity, and cGMP were measured. In the Ad.PRS-eGFP treated group, tissue levels of cGMP were significantly lower in the SHR compared with the WKY atria. NE release was also greater in the SHR, and soluble guanylate cyclase inhibition did not alter evoked [(3)H] NE release in the Ad.PRS-eGFP-treated SHR. All atria treated with Ad.PRS-nNOS had enhanced nNOS activity when compared with Ad.PRS-eGFP atria. Ad.PRS-nNOS in WKY rats reduced NE release compared with the Ad.PRS-eGFP group. Guanylate cyclase inhibition enhanced NE release in both Ad.PRS-nNOS- and Ad.PRS-eGFP-treated WKY atria. Ad.PRS-nNOS restored cGMP levels in the SHR to those seen in the WKY atria. In the SHR, Ad.PRS-nNOS also attenuated NE release compared with Ad.PRS-eGFP group. This was reversed by guanylate cyclase inhibition. We conclude that artificial upregulation of sympathetic nNOS via gene transfer with a noradrenergic promoter may provide a novel approach for correcting peripheral sympathetic hyperactivity in hypertension.
Collapse
Affiliation(s)
- Dan Li
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy & Genetics, Oxford, UK
| | | | | | | | | |
Collapse
|
109
|
Heydemann A, Doherty KR, McNally EM. Genetic modifiers of muscular dystrophy: Implications for therapy. Biochim Biophys Acta Mol Basis Dis 2007; 1772:216-28. [PMID: 16916601 DOI: 10.1016/j.bbadis.2006.06.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2006] [Accepted: 06/22/2006] [Indexed: 10/24/2022]
Abstract
The genetic understanding of the muscular dystrophies has advanced considerably in the last two decades. Over 25 different individual genes are now known to produce muscular dystrophy, and many different "private" mutations have been described for each individual muscular dystrophy gene. For the more common forms of muscular dystrophy, phenotypic variability can be explained by precise mutations. However, for many genetic mutations, the presence of the identical mutation is associated with marked phenotypic range that affects muscle function as well as cardiac function. The explanation for phenotype variability in the muscular dystrophies is only now being explored. The availability of genetically engineered animal models has allowed the generation of single mutations on the background of highly inbred strain. Phenotypic variation that is altered by genetic background argues for the presence of genetic modifier loci that can ameliorate or enhance aspects of the dystrophic phenotype. A number of individual genes have been implicated as modifiers of muscular dystrophy by studies in genetically engineered mouse models of muscular dystrophy. The value of these genes and products is that the pathways identified through these experiments may be exploited for therapy.
Collapse
Affiliation(s)
- Ahlke Heydemann
- Department of Medicine, Section of Cardiology, The University of Chicago, Chicago, IL 60637, USA
| | | | | |
Collapse
|
110
|
Heaton DA, Li D, Almond SC, Dawson TA, Wang L, Channon KM, Paterson DJ. Gene transfer of neuronal nitric oxide synthase into intracardiac Ganglia reverses vagal impairment in hypertensive rats. Hypertension 2007; 49:380-8. [PMID: 17210833 DOI: 10.1161/01.hyp.0000255792.97033.f7] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Hypertension is associated with reduced cardiac vagal activity and decreased atrial guanylate cyclase and cGMP levels. Neuronal production of NO facilitates cardiac parasympathetic transmission, although oxidative stress caused by hypertension may disrupt this pathway. We tested the hypothesis that peripheral vagal responsiveness is attenuated in the spontaneously hypertensive rat (SHR) because of impaired NO-cGMP signaling and that gene transfer of neuronal NO synthase (nNOS) into cholinergic intracardiac ganglia can restore neural function. Cardiac vagal heart rate responses in the isolated SHR atrial/right vagus preparation were significantly attenuated compared with age-matched normotensive Wistar-Kyoto rats. [(3)H] acetylcholine release was also significantly lower in the SHR. The NO donor, sodium nitroprusside, augmented vagal responses to nerve stimulation and [(3)H] acetylcholine release in the Wistar-Kyoto rat, whereas the soluble guanylate cyclase inhibitor 1H-(1,2,4)oxadiazolo(4,3-a)quinoxaline-1-one attenuated [(3)H] acetylcholine release in Wistar-Kyoto atria. No effects of sodium nitroprusside or 1H-(1,2,4)oxadiazolo(4,3-a)quinoxaline-1-one were seen in the SHR during nerve stimulation. In contrast, SHR atria were hyperresponsive to carbachol-induced bradycardia, with elevated production of atrial cGMP. After gene transfer of adenoviral nNOS into the right atrium, vagal responsiveness in vivo was significantly increased in the SHR compared with transfection with adenoviral enhanced green fluorescent protein. Atrial nNOS activity was increased after gene transfer of adenoviral nNOS, as was expression of alpha(1)-soluble guanylate cyclase in both groups compared with adenoviral enhanced green fluorescent protein. In conclusion, a significant component of cardiac vagal dysfunction in hypertension is attributed to an impairment of the postganglionic presynaptic NO-cGMP pathway and that overexpression of nNOS can reverse this neural phenotype.
Collapse
Affiliation(s)
- Daniel A Heaton
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | | | | | | | | | | | | |
Collapse
|
111
|
Cardiac involvement in Beagle-based canine X-linked muscular dystrophy in Japan (CXMDJ): electrocardiographic, echocardiographic, and morphologic studies. BMC Cardiovasc Disord 2006; 6:47. [PMID: 17140458 PMCID: PMC1698931 DOI: 10.1186/1471-2261-6-47] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2006] [Accepted: 12/04/2006] [Indexed: 01/08/2023] Open
Abstract
Background Cardiac mortality in Duchenne muscular dystrophy (DMD) has recently become important, because risk of respiratory failure has been reduced due to widespread use of the respirator. The cardiac involvement is characterized by distinctive electrocardiographic abnormalities or dilated cardiomyopathy, but the pathogenesis has remained obscure. In research on DMD, Golden retriever-based muscular dystrophy (GRMD) has attracted much attention as an animal model because it resembles DMD, but GRMD is very difficult to maintain because of their severe phenotypes. We therefore established a line of dogs with Beagle-based canine X-linked muscular dystrophy in Japan (CXMDJ) and examined the cardiac involvement. Methods The cardiac phenotypes of eight CXMDJ and four normal male dogs 2 to 21 months of age were evaluated using electrocardiography, echocardiography, and histopathological examinations. Results Increases in the heart rate and decreases in PQ interval compared to a normal littermate were detected in two littermate CXMDJ dogs at 15 months of age or older. Distinct deep Q-waves and increase in Q/R ratios in leads II, III, and aVF were detected by 6–7 months of age in all CXMDJ dogs. In the echocardiogram, one of eight of CXMDJ dogs showed a hyperechoic lesion in the left ventricular posterior wall at 5 months of age, but the rest had not by 6–7 months of age. The left ventricular function in the echocardiogram indicated no abnormality in all CXMDJ dogs by 6–7 months of age. Histopathology revealed myocardial fibrosis, especially in the left ventricular posterobasal wall, in three of eight CXMDJ dogs by 21 months of age. Conclusion Cardiac involvement in CXMDJ dogs is milder and has slower progression than that described in GRMD dogs. The distinct deep Q-waves have been ascribed to myocardial fibrosis in the posterobasal region of the left ventricle, but our data showed that they precede the lesion on echocardiogram and histopathology. These findings imply that studies of CXMDJ may reveal not only another causative mechanism of the deep Q-waves but also more information on the pathogenesis in the dystrophin-deficient heart.
Collapse
|
112
|
Duan D. Challenges and opportunities in dystrophin-deficient cardiomyopathy gene therapy. Hum Mol Genet 2006; 15 Spec No 2:R253-61. [PMID: 16987891 PMCID: PMC2581718 DOI: 10.1093/hmg/ddl180] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The last decade has evidenced unprecedented progress in gene therapy of Duchenne and Becker muscular dystrophy (DMD and BMD) skeletal muscle disease. Cardiomyopathy is a leading cause of morbidity and mortality in both patients and carriers of DMD, BMD and X-linked dilated cardiomyopathy. However, there is little advance in heart gene therapy. The gene, the vector, vector delivery, the target tissue and animal models are five fundamental components in developing an effective gene therapy. Intensive effort has been made in optimizing gene transfer vectors and methods. Systemic and/or local delivery of recombinant adeno-associated viral vector have resulted in widespread transduction in the rodent heart. The current challenge is to define other parameters that are essential for a successful gene therapy such as the best candidate gene(s), the optimal expression level and the target tissue. This review focuses on these long-ignored aspects and points out future research directions. In particular, we need to address whether all or only some of the recently developed mini- and microgenes are protective in the heart, whether partial correction can lead to whole heart function improvement, whether over-expression is hazardous and whether correcting skeletal muscle disease can slow down or stop the progression of cardiomyopathy. Discussion is also made on whether the current mouse models can meet these research needs.
Collapse
Affiliation(s)
- Dongsheng Duan
- Department of Molecular Microbiology and Immunology, The University of Missouri School of Medicine, One Hospital Dr., Room M610G, MSB Columbia, MO 65212, USA.
| |
Collapse
|
113
|
Tidball JG, Wehling-Henricks M. The role of free radicals in the pathophysiology of muscular dystrophy. J Appl Physiol (1985) 2006; 102:1677-86. [PMID: 17095633 DOI: 10.1152/japplphysiol.01145.2006] [Citation(s) in RCA: 172] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Null mutation of any one of several members of the dystrophin protein complex can cause progressive, and possibly fatal, muscle wasting. Although these muscular dystrophies arise from mutation of a single gene that is expressed primarily in muscle, the resulting pathology is complex and multisystemic, which shows a broader disruption of homeostasis than would be predicted by deletion of a single-gene product. Before the identification of the deficient proteins that underlie muscular dystrophies, such as Duchenne muscular dystrophy (DMD), oxidative stress was proposed as a major cause of the disease. Now, current knowledge supports the likelihood that interactions between the primary genetic defect and disruptions in the normal production of free radicals contribute to the pathophysiology of muscular dystrophies. In this review, we focus on the pathophysiology that results from dystrophin deficiency in humans with DMD and the mdx mouse model of DMD. Current evidence indicates three general routes through which free radical production can be disrupted in dystrophin deficiency to contribute to the ensuing pathology. First, constitutive differences in free radical production can disrupt signaling processes in muscle and other tissues and thereby exacerbate pathology. Second, tissue responses to the presence of pathology can cause a shift in free radical production that can promote cellular injury and dysfunction. Finally, behavioral differences in the affected individual can cause further changes in the production and stoichiometry of free radicals and thereby contribute to disease. Unfortunately, the complexity of the free radical-mediated processes that are perturbed in complex pathologies such as DMD will make it difficult to develop therapeutic approaches founded on systemic administration of antioxidants. More mechanistic knowledge of the specific disruptions of free radicals that underlie major features of muscular dystrophy is needed to develop more targeted and successful therapeutic approaches.
Collapse
Affiliation(s)
- James G Tidball
- Department of Physiological Science, University of California, Los Angeles, California 90095, USA.
| | | |
Collapse
|
114
|
Williams IA, Allen DG. Intracellular calcium handling in ventricular myocytes from mdx mice. Am J Physiol Heart Circ Physiol 2006; 292:H846-55. [PMID: 17012353 DOI: 10.1152/ajpheart.00688.2006] [Citation(s) in RCA: 138] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Duchenne muscular dystrophy (DMD) is a lethal degenerative disease of skeletal muscle, characterized by the absence of the cytoskeletal protein dystrophin. Some DMD patients show a dilated cardiomyopathy leading to heart failure. This study explores the possibility that dystrophin is involved in the regulation of a stretch-activated channel (SAC), which in the absence of dystrophin has increased activity and allows greater Ca(2+) into cardiomyocytes. Because cardiac failure only appears late in the progression of DMD, we examined age-related effects in the mdx mouse, an animal model of DMD. Ca(2+) measurements using a fluorescent Ca(2+)-sensitive dye fluo-4 were performed on single ventricular myocytes from mdx and wild-type mice. Immunoblotting and immunohistochemistry were performed on whole hearts to determine expression levels of key proteins involved in excitation-contraction coupling. Old mdx mice had raised resting intracellular Ca(2+) concentration ([Ca(2+)](i)). Isolated ventricular myocytes from young and old mdx mice displayed abnormal Ca(2+) transients, increased protein expression of the ryanodine receptor, and decreased protein expression of serine-16-phosphorylated phospholamban. Caffeine-induced Ca(2+) transients showed that the Na(+)/Ca(2+) exchanger function was increased in old mdx mice. Two SAC inhibitors streptomycin and GsMTx-4 both reduced resting [Ca(2+)](i) in old mdx mice, suggesting that SACs may be involved in the Ca(2+)-handling abnormalities in these animals. This finding was supported by immunoblotting data, which demonstrated that old mdx mice had increased protein expression of canonical transient receptor potential channel 1, a likely candidate protein for SACs. SACs may play a role in the pathogenesis of the heart failure associated with DMD. Early in the disease process and before the onset of clinical symptoms increased, SAC activity may underlie the abnormal Ca(2+) handling in young mdx mice.
Collapse
MESH Headings
- Age Factors
- Animals
- Caffeine/pharmacology
- Calcium/metabolism
- Calcium-Binding Proteins/metabolism
- Cardiac Output, Low/etiology
- Cardiac Output, Low/metabolism
- Cardiac Output, Low/pathology
- Cardiac Output, Low/physiopathology
- Cardiomyopathy, Dilated/etiology
- Cardiomyopathy, Dilated/metabolism
- Cardiomyopathy, Dilated/pathology
- Cardiomyopathy, Dilated/physiopathology
- Disease Models, Animal
- Electric Stimulation
- Fibrosis
- Heart Ventricles/metabolism
- Heart Ventricles/physiopathology
- Intercellular Signaling Peptides and Proteins
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Inbred mdx
- Muscular Dystrophy, Animal/complications
- Muscular Dystrophy, Duchenne/complications
- Myocardial Contraction
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/metabolism
- Peptides/pharmacology
- Phosphorylation
- Ryanodine Receptor Calcium Release Channel/metabolism
- Sarcoplasmic Reticulum Calcium-Transporting ATPases/metabolism
- Sodium-Calcium Exchanger/drug effects
- Sodium-Calcium Exchanger/metabolism
- Spider Venoms/pharmacology
- Streptomycin/pharmacology
- TRPC Cation Channels/drug effects
- TRPC Cation Channels/metabolism
- Time Factors
Collapse
Affiliation(s)
- Iwan A Williams
- Bosch Institute, School of Medical Sciences, University of Sydney F13, NSW 2006 Australia
| | | |
Collapse
|
115
|
Pott C, Ren X, Tran DX, Yang MJ, Henderson S, Jordan MC, Roos KP, Garfinkel A, Philipson KD, Goldhaber JI. Mechanism of shortened action potential duration in Na+-Ca2+ exchanger knockout mice. Am J Physiol Cell Physiol 2006; 292:C968-73. [PMID: 16943244 DOI: 10.1152/ajpcell.00177.2006] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In cardiac-specific Na(+)-Ca(2+) exchanger (NCX) knockout (KO) mice, the ventricular action potential (AP) is shortened. The shortening of the AP, as well as a decrease of the L-type Ca(2+) current (I(Ca)), provides a critical mechanism for the maintenance of Ca(2+) homeostasis and contractility in the absence of NCX (Pott C, Philipson KD, Goldhaber JI. Excitation-contraction coupling in Na(+)-Ca(2+) exchanger knockout mice: reduced transsarcolemmal Ca(2+) flux. Circ Res 97: 1288-1295, 2005). To investigate the mechanism that underlies the accelerated AP repolarization, we recorded the transient outward current (I(to)) in patch-clamped myocytes isolated from wild-type (WT) and NCX KO mice. Peak I(to) was increased by 78% and decay kinetics were slowed in KO vs. WT. Consistent with increased I(to), ECGs from KO mice exhibited shortened QT intervals. Expression of the I(to)-generating K(+) channel subunit Kv4.2 and the K(+) channel interacting protein was increased in KO. We used a computer model of the murine AP (Bondarenko VE, Szigeti GP, Bett GC, Kim SJ, and Rasmusson RL. Computer model of action potential of mouse ventricular myocytes. Am J Physiol Heart Circ Physiol 287: 1378-1403, 2004) to determine the relative contributions of increased I(to), reduced I(Ca), and reduced NCX current (I(NCX)) on the shape and kinetics of the AP. Reduction of I(Ca) and elimination of I(NCX) had relatively small effects on the duration of the AP in the computer model. In contrast, AP repolarization was substantially accelerated when I(to) was increased in the computer model. Thus, the increase in I(to), and not the reduction of I(Ca) or I(NCX), is likely to be the major mechanism of AP shortening in KO myocytes. The upregulation of I(to) may comprise an important regulatory mechanism to limit Ca(2+) influx via a reduction of AP duration, thus preventing Ca(2+) overload in situations of reduced myocyte Ca(2+) extrusion capacity.
Collapse
Affiliation(s)
- Christian Pott
- Cardiovascular Research Laboratory, MRL 3-645, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095-1760, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
116
|
Anderson JE. The satellite cell as a companion in skeletal muscle plasticity: currency, conveyance, clue, connector and colander. ACTA ACUST UNITED AC 2006; 209:2276-92. [PMID: 16731804 DOI: 10.1242/jeb.02088] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Satellite cells are companions to voluntary muscle fibres, and are named for their intimate positional or ;satellite' relationship, as if revolving around fibres, like a satellite moon around the earth. Studies on the nature of at least some satellite cells, including their capabilities for self-renewal and for giving rise to multiple lineages in a stem cell-like function, are exploring the molecular basis of phenotypes described by markers of specialized function and gene expression in normal development, neuromuscular disease and aging. In adult skeletal muscle, the self-renewing capacity of satellite cells contributes to muscle growth, adaptation and regeneration. Muscle remodeling, such as demonstrated by changes in myofibre cross-sectional area and length, nerve and tendon junctions, and fibre-type distribution, occur in the absence of injury and provide broad functional and structural diversity among skeletal muscles. Those contributions to plasticity involve the satellite cell in at least five distinct roles, here described using metaphors for behaviour or the investigator's perspective. Satellite cells are the 'currency' of muscle; have a 'conveyance' role in adaptation by domains of cytoplasm along a myofibre; serve researchers, through a marker role, as 'clues' to various activities of muscle; are 'connectors' that physically, and through signalling and cell-fibre communications, bridge myofibres to the intra- and extra-muscular environment; and are equipped as metabolic and genetic filters or 'colanders' that can rectify or modulate particular signals. While all these roles are still under exploration, each contributes to the plasticity of skeletal muscle and thence to the overall biology and function of an organism. The use of metaphor for describing these roles helps to clarify and scrutinize the definitions that form the basis of our understanding of satellite cell biology: the metaphors provide the construct for various approaches to detect or test the nature of satellite cell functions in skeletal muscle plasticity.
Collapse
Affiliation(s)
- Judy E Anderson
- Department of Human Anatomy and Cell Science, Faculty of Medicine, University of Manitoba, Winnipeg, MB, R3E 0W3, Canada.
| |
Collapse
|
117
|
Affiliation(s)
- Jeffrey A Towbin
- Department of Pediatrics (Cardiology), Baylor College of Medicine, Texas Children's Hospital, Houston, TX 77030, USA.
| | | |
Collapse
|
118
|
Wang L, Li D, Plested CP, Dawson T, Teschemacher AG, Paterson DJ. Noradrenergic neuron-specific overexpression of nNOS in cardiac sympathetic nerves decreases neurotransmission. J Mol Cell Cardiol 2006; 41:364-70. [PMID: 16806265 DOI: 10.1016/j.yjmcc.2006.05.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2006] [Revised: 05/10/2006] [Accepted: 05/11/2006] [Indexed: 11/24/2022]
Abstract
Gene transfer of neuronal nitric oxide synthase (nNOS) with nonspecific adenoviral vectors can cause promiscuous transduction. We provide direct evidence that nNOS targeted only to cardiac sympathetic neurons inhibits sympathetic neurotransmission. An adenovirus constructed with a noradrenergic neuron-specific promoter (PRSx8), driving nNOS or enhanced green fluorescence protein (eGFP) gene expression caused exclusive expression in tyrosine hydroxylase (TH) positive rat cardiac sympathetic neurons. There was no detectable leakage of transgene expression in other cell types in the preparation nor did the transgene express in choline acetyltransferase (CHAT)-positive intracardiac cholinergic ganglia. Functionally, Ad.PRS-nNOS gene transfer increased nNOS activity and significantly reduced norephinephrine release evoked by field stimulation of isolated right atria. These effects were reversed by the NOS inhibitor N(omega)-Nitro-L-arginine. Our results demonstrate that noradrenergic cell-specific gene transfer with nNOS can inhibit cardiac sympathetic neurotransmission. This targeted technique may provide a novel method for reducing presynaptic sympathetic hyperactivity.
Collapse
Affiliation(s)
- L Wang
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Oxford, UK
| | | | | | | | | | | |
Collapse
|
119
|
Yue Y, Liu M, Duan D. C-terminal-truncated microdystrophin recruits dystrobrevin and syntrophin to the dystrophin-associated glycoprotein complex and reduces muscular dystrophy in symptomatic utrophin/dystrophin double-knockout mice. Mol Ther 2006; 14:79-87. [PMID: 16563874 PMCID: PMC2581714 DOI: 10.1016/j.ymthe.2006.01.007] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2005] [Revised: 01/03/2006] [Accepted: 01/12/2006] [Indexed: 01/19/2023] Open
Abstract
C-terminal-truncated (DeltaC) microdystrophin is being developed for Duchenne muscular dystrophy gene therapy. Encouraging results have been achieved in the mdx mouse model. Unfortunately, mdx mice do not display the same phenotype as human patients. Evaluating DeltaC microdystrophin in a symptomatic model will be of significant relevance to human trials. Utrophin/dystrophin double-knockout (u-dko) mice were developed to model severe dystrophic changes in human patients. In this study we evaluated the therapeutic effect of the DeltaR4-R23/DeltaC microdystrophin gene (DeltaR4/DeltaC) after serotype-6 adeno-associated virus-mediated gene transfer in neonatal u-dko muscle. At 2 months after gene transfer, the percentage of centrally nucleated myofiber was reduced from 89.2 to 3.4% and muscle weight was normalized. Furthermore, we have demonstrated for the first time that DeltaC microdystrophin can eliminate interstitial fibrosis and macrophage infiltration and restore dystrobrevin and syntrophin to the dystrophin-associated glycoprotein complex. Interestingly neuronal nitric oxide synthase was not restored. The most impressive results were achieved in muscle force measurement. Neonatal gene therapy increased twitch- and tetanic-specific force. It also brought the response to eccentric contraction-induced injury to the normal range. In summary, our results suggest that the DeltaR4/DeltaC microgene holds great promise in preventing muscular dystrophy.
Collapse
Affiliation(s)
| | | | - Dongsheng Duan
- To whom correspondence and reprint requests should be addressed. Fax: +1 573 882 4287. E-mail:
| |
Collapse
|
120
|
Archer JD, Vargas CC, Anderson JE. Persistent and improved functional gain in mdx dystrophic mice after treatment with L-arginine and deflazacort. FASEB J 2006; 20:738-40. [PMID: 16464957 DOI: 10.1096/fj.05-4821fje] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Although an increase in nitric oxide (NO) in muscle is reported to improve the outcome of deflazacort treatment for mdx mouse muscular dystrophy, the genetic homologue of Duchenne muscular dystrophy (DMD), the impact such treatment on the functional outcomes of the disease, including fiber susceptibility to exercise-induced injury, is not established. Experiments were designed to test whether treatment with deflazacort and L-arginine (a substrate for NO synthase, NOS) would change the extent of fiber injury induced by 24 h of voluntary exercise. The impact of exercise-related injury to induce a secondary regenerative response by muscle was also examined as corroborating evidence of muscle damage. Dystrophic mdx mice were treated for 3 wk with placebo, deflazacort, or deflazacort plus either L-arginine or N(G)-nitro-L-arginine methyl ester (a NOS inhibitor). Deflazacort, especially combined with L-arginine, spared quadriceps muscle from injury-induced regeneration (myf5 expression) compared with placebo treatment, despite an increase in membrane permeability immediately after exercise (assessed by Evans blue dye infiltration). Deflazacort alone prevented the typical progressive loss of function (measured as voluntary distance run over 24 h) that was observed 3 months later in placebo-treated mice. Therefore, combined deflazacort plus L-arginine treatment spared mdx dystrophic limb muscle from exercise-induced damage and the need for regeneration and induced a persistent functional improvement in distance run. Results suggest a potential new treatment option for improving the quality of life for boys with DMD.
Collapse
Affiliation(s)
- Jonathan D Archer
- Department of Human Anatomy and Cell Science, Faculty of Medicine, University of Manitoba, Winnipeg, Canada
| | | | | |
Collapse
|