Fibre-related nitric oxide synthase (NOS) in Duchenne muscular dystrophy

Punkt, Karla; Schering, Stefan; Fritzsche, M.; Asmussen, G; Samoilova, Vera; Müller, Frank-Ulrich; Schmitz, Wilhelm; Hasselblatt, Martin; Paulus, W.; Müller‐Werdan, Ursula; Slezák, J; Koehler, Gabriele; Boecker, Werner; Buchwalow, Igor

doi:10.1016/j.acthis.2007.01.001

Cited by 13 publications

(9 citation statements)

References 16 publications

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“…1A ). For NOS 1 and 3, the same fi ber type specifi c expression was detected as previously shown ( Punkt et al, 2007 ). Despite the signifi cant differences in net NOS1-3 protein expression, there was no difference in fi ber type specifi c NOS 1-3 expression between subjects with NGT and T1D.…”

Section: Nos-expression Of Muscles In Type 1 Diabetessupporting

confidence: 81%

“…Expression of NOS 1-3 isoforms was ~ 15 % reduced in skeletal muscle of T1D compared to NGT subjects. Using a powerful immunohistochemical technique in combination with signal amplifi cation ( Buchwalow, 2001 ), we have previously shown marked NOS expression in FOG fi bers ( Punkt et al, 2007 ). Therefore, the 13.5 % reduction in the NOS-positive FOG fi bers in T1D muscle is most likely the predominant cause for decreased NOS protein concentration in type 1 diabetic skeletal muscles.…”

Section: Discussionmentioning

confidence: 99%

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Metabolic Profile and Nitric Oxide Synthase Expression of Skeletal Muscle Fibers are Altered in Patients with Type 1 Diabetes

Fritzsche¹,

Blüher²,

Schering³

et al. 2008

Exp Clin Endocrinol Diabetes

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We investigate muscle fiber composition, fiber-specific glycolytic and oxidative enzyme capacity and nitric oxide synthase (NOS) expression in skeletal muscle of patients with type 1 diabetes (T1D) compared to individuals with normal glucose tolerance (NGT). Vastus lateralis muscle was obtained by percutaneous biopsy from 7 T1D patients and 10 healthy controls with similar characteristics. Using cytophotometry, muscle fiber composition and fiber type-specific glycolytic and oxidative enzyme activities were measured in slow oxidative (SO), fast oxidative glycolytic (FOG) and fast glycolytic (FG) fibers. In addition, NOS 1-3 protein expression was mea-sured. The glycolytic fiber fraction was 1.4 fold higher, whereas FOG and SO fiber fractions were significantly reduced by 13.5% and 6.2% in skeletal muscle from T1D patients. Glycolytic enzyme activities and fiber-specific ratio of glycolytic relative to oxidative enzyme activity were significantly higher in all fiber types of T1D patients and correlated with HbA (1c). Expression of NOS1-3 isoforms was reduced in skeletal muscle of T1D subjects. Increased glycolytic enzyme activity in muscle of T1D patients is most likely due to both a higher number of fast glycolytic fibers and a shift towards increased glycolytic metabolism in all fiber types. Alterations in muscle fiber distribution and enzyme activities seem to be due to impaired long-term glycemic control.

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Section: Nos-expression Of Muscles In Type 1 Diabetessupporting

confidence: 81%

Section: Discussionmentioning

confidence: 99%

Metabolic Profile and Nitric Oxide Synthase Expression of Skeletal Muscle Fibers are Altered in Patients with Type 1 Diabetes

Fritzsche¹,

Blüher²,

Schering³

et al. 2008

Exp Clin Endocrinol Diabetes

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“…Given that dystrophic muscles are characterized by collapsed myofibers and a disorganized cytoskeleton [ 38 - 42 ], we determined whether myofiber collapse was also associated with local proliferation of MPCs in vivo . We injected EBD into mdx mice, a model of Duchenne muscular dystrophy characterized by a high number of degenerative myofibers [ 38 ].…”

Section: Resultsmentioning

confidence: 99%

“…They are characterized by an extreme shortening of the sarcomeres and an abnormal band pattern. Collapsed myofibers have been observed following extreme eccentric muscle action [ 54 ] and in dystrophic muscles [ 41 , 42 ] but, to our knowledge, they have never been investigated in vitro . Unlike traditional primary myogenic cultures prepared from enzymatically dissociated whole muscle, individual myofiber cultures make it possible to study satellite cells and their progeny within their anatomical niche under the basal lamina.…”

Section: Discussionmentioning

confidence: 99%

Increased microenvironment stiffness in damaged myofibers promotes myogenic progenitor cell proliferation

et al. 2015

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BackgroundThe stiffness of the myogenic stem cell microenvironment markedly influences the ability to regenerate tissue. We studied the effect of damaged myofibers on myogenic progenitor cell (MPC) proliferation and determined whether the structural integrity of the microenvironment contributes to phenotypic changes.MethodsIndividual myofibers were isolated and cultured for 6 days. During this period, the cytoskeleton of myofibers and transcription factors regulating MPC differentiation were characterized by immunostaining. Atomic Force Microscopy (AFM) was performed to measure stiffness of cultured myofibers. Healthy and damaged myofibers, and their associated MPCs, were studied in skeletal muscle from dystrophic and tenotomy mouse models. MPCs were cultured on stiffness-tunable substrates, and their phenotypes were assessed by immunostaining of myogenic transcription factors.ResultsWe showed that individual myofibers tend to shrink or collapse when cultured ex vivo starting from day 1 and that this is associated with a marked increase in the number of proliferative MPCs (Pax7+MyoD+). The myofibers collapsed due to a loss of viability as shown by Evans blue dye uptake and the disorganization of their cytoskeletons. Interestingly, collapsed myofibers in mdx skeletal muscles were similar to damaged myofibers in that they lose their viability, have a disorganized cytoskeleton (actin and α-actinin), and display local MPC (MyoD+) proliferation at their periphery. In a tenotomy model that causes loss of muscle tension, the cytoskeletal disorganization of myofibers also correlated with the activation/proliferation of MPCs. A deeper analysis of collapsed myofibers revealed that they produce trophic factors that influence MPC proliferation. In addition, collapsed myofibers expressed several genes related to the basal lamina. Immunostaining revealed the presence of fibronectin in the basal lamina and the cytoplasm of damaged myofibers. Lastly, using atomic force microscopy (AFM), we showed that collapsed myofibers exhibit greater stiffness than intact myofibers. Growing MPCs on a 2-kPa polyacrylamide-based substrate, exempt of additional microenvironmental cues, recapitulated proliferation and reduced spontaneous differentiation compared to growth on a 0.5-kPa substrate.ConclusionsOur results support the notion that collapsed or damaged myofibers increase the structural stiffness of the satellite cell microenvironment, which in addition to other cues such as trophic factors and changes in extracellular matrix composition, promotes the proliferation and maintenance of MPCs, required for myofiber repair.Electronic supplementary materialThe online version of this article (doi:10.1186/s13395-015-0030-1) contains supplementary material, which is available to authorized users.

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“…For nNOS localization, IHCs were also run using a TSA (tyramide signal amplification) kit (Perkin-Elmer, Waltham, MA) to enhance localization of both sarcolemmal and cytosolic locations of nNOS, as recommended by Punkt et al (31). Within each protein of interest, slides from samples in all three groups were completed during the same day.…”

Section: Animalsmentioning

confidence: 99%

EUK-134 ameliorates nNOSμ translocation and skeletal muscle fiber atrophy during short-term mechanical unloading

Lawler

Kunst

Hord

et al. 2014

American Journal of Physiology-Regulatory, Integrative and Comp

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. EUK-134 ameliorates nNOS translocation and skeletal muscle fiber atrophy during short-term mechanical unloading. Am J Physiol Regul Integr Comp Physiol 306: R470-R482, 2014. First published January 29, 2014 doi:10.1152/ajpregu.00371.2013.-Reduced mechanical loading during bedrest, spaceflight, and casting, causes rapid morphological changes in skeletal muscle: fiber atrophy and reduction of slow-twitch fibers. An emerging signaling event in response to unloading is the translocation of neuronal nitric oxide synthase (nNOS) from the sarcolemma to the cytosol. We used EUK-134, a cellpermeable mimetic of superoxide dismutase and catalase, to test the role of redox signaling in nNOS translocation and muscle fiber atrophy as a result of short-term (54 h) hindlimb unloading. Fischer-344 rats were divided into ambulatory control, hindlimb-unloaded (HU), and hindlimb-unloaded ϩ EUK-134 (HU-EUK) groups. EUK-134 mitigated the unloading-induced phenotype, including muscle fiber atrophy and muscle fiber-type shift from slow to fast. nNOS immunolocalization at the sarcolemma of the soleus was reduced with HU, while nNOS protein content in the cytosol increased with unloading. Translocation of nNOS from the sarcolemma to cytosol was virtually abolished by EUK-134. EUK-134 also mitigated dephosphorylation at Thr-32 of FoxO3a during HU. Hindlimb unloading elevated oxidative stress (4-hydroxynonenal) and increased sarcolemmal localization of Nox2 subunits gp91phox (Nox2) and p47phox, effects normalized by EUK-134. Thus, our findings are consistent with the hypothesis that oxidative stress triggers nNOS translocation from the sarcolemma and FoxO3a dephosphorylation as an early event during mechanical unloading. Thus, redox signaling may serve as a biological switch for nNOS to initiate morphological changes in skeletal muscle fibers. atrophy; disuse; skeletal muscle; nNOS; oxidative stress; FoxO3a SKELETAL MUSCLE IS A HIGHLY specialized and adaptable mesodermic tissue capable of rapid remodeling in response to changes in mechanical loading and stretch (28, 38). Transmittance and detection of loading in skeletal muscle are paramount in regulating differentiation, cell growth, and protein turnover. The ability to sense and relay loading (i.e., mechanotransduction) is, in part, performed by proteins adjacent to and spanning cell membranes (i.e., sarcolemma) in skeletal muscle (47). Mechanical unloading that occurs with limb casting, splinting, bed rest, and spaceflight, elicits a substantial loss of forcegenerating capacity, linked to a diminishment in muscle fiber cross-sectional area or atrophy (12, 23). The unloading phenotype also includes a shift of a portion of skeletal muscle fibers from slow-twitch to fast-twitch (12). Muscle atrophy that occurs with unloading is coupled to a net loss of contractile proteins, a function of increased protein degradation combined with a decrease in protein synthesis (12,23). Recent studies emphasize the importance of proteolytic pathways, including ubiquitin proteasome, calpains, autophagy...

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Fibre-related nitric oxide synthase (NOS) in Duchenne muscular dystrophy

Cited by 13 publications

References 16 publications

Metabolic Profile and Nitric Oxide Synthase Expression of Skeletal Muscle Fibers are Altered in Patients with Type 1 Diabetes

Metabolic Profile and Nitric Oxide Synthase Expression of Skeletal Muscle Fibers are Altered in Patients with Type 1 Diabetes

Increased microenvironment stiffness in damaged myofibers promotes myogenic progenitor cell proliferation

EUK-134 ameliorates nNOSμ translocation and skeletal muscle fiber atrophy during short-term mechanical unloading

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