mdx muscle pathology is independent of nNOS perturbation

Crosbie, Rachelle H.; Straub, Volker; Yun, Hye Young; Lee, Jane C.; Rafael, Jill A.; Chamberlain, Jeffrey S.; Dawson, Valina L.; Dawson, Ted M.; Campbell, Kevin P.

doi:10.1093/hmg/7.5.823

Cited by 101 publications

(93 citation statements)

References 40 publications

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“…A previous study indicated that the rod domain encoded by exons 45-48 of the dystrophin gene was required for localization of nNOS to the sarcolemma. 20 However, Crosbie et al, 21 reported that a minidystrophin (from a Becker MD patient) missing exons 17-48 was able to restore nNOS to the sarcolemma in transgenic mdx mice, and also, the deletion of exons 71-74 or exons 75-78 of the C-terminal region in transgenic mice did not affect the expression of nNOS. Our canine minidystrophin construct (containing exons 1-14 and exons 55-70), which lacked exons 15-54 and Figure 4 Protection of myofiber embrane Integrity.…”

Section: Discussionmentioning

confidence: 99%

“…21 Although nNOS does not play a major role in DMD pathology, 21,22 its normal submembrane location in myofibers is believed to facilitate microcapillary blood vessel dilation during exercises. 23 It may also play some role in yet to be defined signal-transduction pathways.…”

Section: Discussionmentioning

confidence: 99%

“…nNOS gene knockout in mdx mice does not exacerbate the dystrophic phonotype. 21 However, forced overexpression of nNOS is reported to reduce muscle pathology in mdx mice primarily by keeping inflammation in check. 24 In DMD and mdx muscles, the nNOS has lost its submembrane anchor and become diffused and diminished in the cytoplasma of the myofibers.…”

Section: Discussionmentioning

confidence: 99%

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A canine minidystrophin is functional and therapeutic in mdx mice

Wang

Qiao

et al. 2008

Gene Ther

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Duchenne muscular dystrophy (DMD) is the most common and lethal genetic muscle disorder lacking a curative treatment. We wish to use the dystrophin-deficient golden retriever muscular dystrophy (GRMD) dog, a canine model of DMD, to investigate adeno-associated virus (AAV) vectormediated minidystrophin gene therapy. The dog model is useful in evaluating vector dose requirement and immunological consequences owing to its large size and outbred nature. In this study, we have cloned and constructed a canine minidystrophin gene vector. Owing to limited availability of the GRMD dogs, here we first examined the functions and therapeutic effects of the canine minidystrophin in the mdx mouse model. We observed efficient minigene expression without cellular immune responses in mdx mice after AAV1-cMinidys vector intramuscular injection. We also observed restoration of the missing dystrophin-associated protein complex (DPC) onto the sarcolemma, including sarcoglycans and dystrobrevin, and a partial restoration of a-syntrophin and neural nitric oxide synthase (nNOS). In addition, minidystrophin treatment ameliorated dystrophic pathology, such as fibrosis and myofiber central nucleation (CN). CN remained minimal (o2%) after AAV injection in the neonatal mdx mice and was reduced from more than 75% to about 25% after AAV injection in adult mdx mice. Finally, in vivo cell membrane leakage test with Evans blue dye showed that the canine minidystrophin could effectively protect the myofiber plasma membrane integrity. Our results, thus, demonstrated the functionality and therapeutic potential of the canine minidystrophin and paved its way for further testing in the GRMD dog model.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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A canine minidystrophin is functional and therapeutic in mdx mice

Wang

Qiao

et al. 2008

Gene Ther

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“…Moreover, the fact that such dystrophin-dependent mechanical nNOS signaling is independent of a physical interaction between nNOS and the cardiac DGC suggests that the DGC is not merely a passive scaffold for nNOS, but rather is an active regulator of a signaling pathway that controls nNOS activity in cardiac muscle, and possibly in skeletal muscle as well. A model in which dystrophin loss results in loss of AMPKdependent regulation of nNOS also would help explain why deletion of nNOS does not dramatically worsen muscle pathology in mdx mice (52,53), because the activation of any nNOS expressed in dystrophin-deficient muscle would already be impaired.…”

Section: Discussionmentioning

confidence: 99%

Dystrophin–glycoprotein complex regulates muscle nitric oxide production through mechanoregulation of AMPK signaling

Garbincius

Michele

2015

Proc. Natl. Acad. Sci. U.S.A.

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Patients deficient in dystrophin, a protein that links the cytoskeleton to the extracellular matrix via the dystrophin-glycoprotein complex (DGC), exhibit muscular dystrophy, cardiomyopathy, and impaired muscle nitric oxide (NO) production. We used live-cell NO imaging and in vitro cyclic stretch of isolated adult mouse cardiomyocytes as a model system to investigate if and how the DGC directly regulates the mechanical activation of muscle NO signaling. Acute activation of NO synthesis by mechanical stretch was impaired in dystrophin-deficient mdx cardiomyocytes, accompanied by loss of stretch-induced neuronal NO synthase (nNOS) S1412 phosphorylation. Intriguingly, stretch induced the acute activation of AMP-activated protein kinase (AMPK) in normal cardiomyocytes but not in mdx cardiomyocytes, and specific inhibition of AMPK was sufficient to attenuate mechanoactivation of NO production. Therefore, we tested whether direct pharmacologic activation of AMPK could bypass defective mechanical signaling to restore nNOS activity in dystrophin-deficient cardiomyocytes. Indeed, activation of AMPK with 5-aminoimidazole-4-carboxamide riboside or salicylate increased nNOS S1412 phosphorylation and was sufficient to enhance NO production in mdx cardiomyocytes. We conclude that the DGC promotes the mechanical activation of cardiac nNOS by acting as a mechanosensor to regulate AMPK activity, and that pharmacologic AMPK activation may be a suitable therapeutic strategy for restoring nNOS activity in dystrophin-deficient hearts and muscle.T he muscular dystrophies are a group of muscle wasting disorders characterized by progressive weakening and degeneration of striated muscle. The most common form is Duchenne muscular dystrophy (DMD), an X-linked disorder caused by genetic disruption of dystrophin (1) that affects 1 in 3,500-5,000 males (2, 3). DMD and several other types of muscular dystrophy result from disruption of the dystrophin-glycoprotein complex (DGC), a structure that spans the sarcolemma and forms a mechanical linkage between the cytoskeleton and the extracellular matrix via the association of dystrophin with subsarcolemmal γ-actin and the binding of α-dystroglycan to laminin (4). The generally accepted role for this complex is to act as a molecular shock absorber and stabilize the plasma membrane during muscle contraction. Disruption of the DGC's linkage between the cytoskeleton and extracellular matrix, such as occurs in DMD (1, 5-7) or with the disruption of α-dystroglycan-laminin binding in glycosylation-deficient muscular dystrophies (8, 9), leads to destabilization of the plasma membrane, rendering skeletal muscle fibers and cardiomyocytes susceptible to stretch-or contraction-induced injury and cell death (10)(11)(12)(13)(14).In addition to this structural role, a signaling function for the DGC has been proposed based on its association with several signaling proteins including Grb2-Sos1 (15), MEK and ERK (16), heterotrimeric G protein subunits (17, 18), archvillin (19), and neuronal nitric oxide synthase (n...

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“…In patients with Beckers muscular dystrophy due to mutations in the spectrin-like domains of dystrophin, and in mutant mice lacking the dystrophin-associated dystrobrevin, nNOS but not other components of the dystrophin complex are lost from the sarcolemma Grady et al, 1999). Curiously however, mutant mice lacking nNOS do not show muscular dystrophy (Chao et al, 1998;Crosbie et al, 1998). Taken together, these studies suggest that whereas loss of skeletal muscle NO does not itself cause dystrophy, the lack of nNOS in Duchenne muscular dystrophy augments the damage caused by absence of the structural dystrophin glycoprotein complex.…”

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confidence: 99%

Nitric oxide signaling specificity — the heart of the problem

Bredt

2003

Journal of Cell Science

134

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Nitric oxide (NO) is a gaseous free radical that functions as an endogenous mediator in numerous tissues. Because NO is both reactive and highly diffusible, its formation must be tightly regulated to control its synthesis and to specify its signaling. Indeed, molecular studies of the NO synthase(NOS) family of enzymes have elaborated a variety of mechanisms, including protein interactions, lipid modifications and protein phosphorylation cascades that spatially and temporally control NO biosynthesis. These mechanisms determine both the upstream cellular signals that stimulate NO formation and the downstream molecular targets for NO. Understanding these cellular pathways that control NOS will help us to elucidate the functional roles of NO and provide novel strategies to treat diseases associated with NO abnormalities.

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mdx muscle pathology is independent of nNOS perturbation

Cited by 101 publications

References 40 publications

A canine minidystrophin is functional and therapeutic in mdx mice

A canine minidystrophin is functional and therapeutic in mdx mice

Dystrophin–glycoprotein complex regulates muscle nitric oxide production through mechanoregulation of AMPK signaling

Nitric oxide signaling specificity — the heart of the problem

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