Muscle Atrophy Due to Nerve Damage Is Accompanied by Elevated Myofibrillar Protein Synthesis Rates

Langer, Henning T.; Senden, Joan M.; Gijsen, Annemie P.; Kempa, Stefan; Loon, Luc J. C. van; Spuler, Simone

doi:10.3389/fphys.2018.01220

Cited by 30 publications

(33 citation statements)

References 51 publications

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“…All bands on the membrane (Fig. 3B,C) were normalized to total protein content per corresponding lane on the gel (Supplement S2 and S3) as described previously 12,[16][17][18] .…”

Section: Elevated Levels Of Proteins Associated With Membrane Damagementioning

confidence: 99%

“…The secondary antibodies were applied accordingly and the membrane imaged via infrared imaging (Odyssey, LI-COR Biosciences, USA). We and others have previously found that normalizing protein levels to housekeeping proteins is less reliable than normalizing to total protein content 12,16,17 . We therefore normalized all levels of our proteins to total protein content of the gel stained with Coomassie Blue.…”

mentioning

confidence: 92%

“…Animals. We have previously described the constriction injury model and skeletal muscle atrophy in the same animals that were investigated in this study 12 . Briefly, male Sprague-Dawley rats (Charles River, Germany) between 20-21 weeks of age were housed in individual cages.…”

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confidence: 99%

“…Subsequently the data were read into our house intern software MAUI-VIA for annotation and quantification of individual metabolites, more elaborately described elsewhere 15 . immunohistochemistry. Cryosections for immunohistochemistry have been prepared as described previously 12 . Sectioned samples were left 1 h at room temperature to dry, before being fixated in formaldehyde for 5 min.…”

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confidence: 99%

“…After lysing the samples they were centrifuged for 15 min (13,200 rpm) and the supernatant collected. Semi dry transfer was conducted as described previously 12 . The following antibodies were used: Dysferlin HAMLET (Novocastra, Germany), Cyclophillin A (#ab41684) (Abcam, UK), Akt (#9272), pAkt (#9271), AMPK (#2603), pAMPK (#2535) (Cell Signaling, USA).…”

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confidence: 99%

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Nerve damage induced skeletal muscle atrophy is associated with increased accumulation of intramuscular glucose and polyol pathway intermediates

Langer

Afzal

Kempa

et al. 2020

Sci Rep

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Perturbations in skeletal muscle metabolism have been reported for a variety of neuromuscular diseases. However, the role of metabolism after constriction injury to a nerve and the associated muscle atrophy is unclear. We have analyzed rat tibialis anterior (TA) four weeks after unilateral constriction injury to the sciatic nerve (DMG) and in the contralateral control leg (CTRL) (n = 7) to investigate changes of the metabolome, immunohistochemistry and protein levels. Untargeted metabolomics identified 79 polar metabolites, 27 of which were significantly altered in DMG compared to CTRL. Glucose concentrations were increased 2.6-fold in DMG, while glucose 6-phosphate (G6-P) was unchanged. Intermediates of the polyol pathway were increased in DMG, particularly fructose (1.7fold). GLUT4 localization was scattered as opposed to clearly at the sarcolemma. Despite the altered localization, we found GLUT4 protein levels to be increased 7.8-fold while GLUT1 was decreased 1.7fold in nerve damaged TA. PFK1 and GS levels were both decreased 2.1-fold, indicating an inability of glycolysis and glycogen synthesis to process glucose at sufficient rates. In conclusion, chronic nerve constriction causes increased GLUT4 levels in conjunction with decreased glycolytic activity and glycogen storage in skeletal muscle, resulting in accumulation of intramuscular glucose and polyol pathway intermediates. Skeletal muscle atrophy is a pathological condition associated with many diseases. While protein metabolism is thought to be the main regulator of muscle size, many situations of atrophy and neuromuscular diseases are accompanied by changes to substrate metabolism as well. Critical illness myopathy (CIM) is a condition for which disturbances of glucose metabolism have been reported by our laboratory and others 1. Specifically, we have found the primary glucose transporter GLUT4 to be insufficiently translocated in CIM patients, resulting in decreased glucose supply and reduced AMPK activity 2. Besides CIM, a number of other neuromuscular disorders have been found to be show signs of changes to glucose metabolism in skeletal muscle such as amyotrophic lateral sclerosis (ALS), Charcot-Marie-Tooth neuropathy (CMT) or spinal muscular atrophy (SMA) 3-5. For example, it has been found that concentrations of glucose as well as fructose are increased in skeletal muscle samples of ALS patients, often accompanied by an early onset of insulin resistance 6. Early research in respect to nerve damage and glucose metabolism has reported that denervation is followed by insulin resistance, reduced glucose transport into the muscle, less glucose abundance and transiently decreased GLUT4 levels 7-9. A more recent study in mice found that despite decreased GLUT4 mRNA abundance, long term denervation was associated with increased GLUT4 protein levels potentially regulated by increased Akt activity 10. The same study found that glucose uptake in

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“…All bands on the membrane (Fig. 3B,C) were normalized to total protein content per corresponding lane on the gel (Supplement S2 and S3) as described previously 12,[16][17][18] .…”

Section: Elevated Levels Of Proteins Associated With Membrane Damagementioning

confidence: 99%

mentioning

confidence: 92%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Nerve damage induced skeletal muscle atrophy is associated with increased accumulation of intramuscular glucose and polyol pathway intermediates

Langer

Afzal

Kempa

et al. 2020

Sci Rep

Self Cite

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Determining the contributions of protein synthesis and breakdown to muscle atrophy requires non‐steady‐state equations

Kobak

Lawrence

Pharaoh

et al. 2021

J cachexia sarcopenia muscle

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Background Ageing and cachexia cause a loss of muscle mass over time, indicating that protein breakdown exceeds protein synthesis. Deuterium oxide (D2O) is used for studies of protein turnover because of the advantages of long‐term labelling, but these methods introduce considerations that have been largely overlooked when studying conditions of protein gain or loss. The purpose of this study was to demonstrate the importance of accounting for a change in protein mass, a non‐steady state, during D2O labelling studies while also exploring the contribution of protein synthesis and breakdown to denervation‐induced muscle atrophy. Methods Adult (6 months) male C57BL/6 mice (n = 14) were labelled with D2O for a total of 7 days following unilateral sciatic nerve transection to induce denervation of hindlimb muscles. The contralateral sham limb and nonsurgical mice (n = 5) were used as two different controls to account for potential crossover effects of denervation. We calculated gastrocnemius myofibrillar and collagen protein synthesis and breakdown assuming steady‐state or using non‐steady‐state modelling. We measured RNA synthesis rates to further understand ribosomal turnover during atrophy. Results Gastrocnemius mass was less in denervated muscle (137 ± 9 mg) compared with sham (174 ± 15 mg; P < 0.0001) or nonsurgical control (162 ± 5 mg; P < 0.0001). With steady‐state calculations, fractional synthesis and breakdown rates (FSR and FBR) were lower in the denervated muscle (1.49 ± 0.06%/day) compared with sham (1.81 ± 0.09%/day; P < 0.0001) or nonsurgical control (2.27 ± 0.04%/day; P < 0.0001). When adjusting for change in protein mass, FSR was 4.21 ± 0.19%/day in denervated limb, whereas FBR was 4.09 ± 0.22%/day. When considering change in protein mass (ksyn), myofibrillar synthesis was lower in denervated limb (2.44 ± 0.14 mg/day) compared with sham (3.43 ± 0.22 mg/day; P < 0.0001) and non‐surgical control (3.74 ± 0.12 mg/day; P < 0.0001), whereas rate of protein breakdown (kdeg, 1/t) was greater in denervated limb (0.050 ± 0.003) compared with sham (0.019 ± 0.001; P < 0.0001) and nonsurgical control (0.023 ± 0.000; P < 0.0001). Muscle collagen breakdown was completely inhibited during denervation. There was a strong correlation (r = 0.83, P < 0.001) between RNA and myofibrillar protein synthesis in sham but not denervated muscle. Conclusions We show conflicting results between steady‐ and non‐steady‐state calculations on myofibrillar protein synthesis and breakdown during periods of muscle loss. We also found that collagen accumulation was largely from a decrease in collagen breakdown. Comparison between sham and non‐surgical control demonstrated a crossover effect of denervation on myofibrillar protein synthesis and ribosomal biogenesis, which impacts study design for unilateral atrophy studies. These considerations are important because not accounting for them can mislead therapeutic attempts to maintain muscle mass.

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Skeletal Muscle Aging Atrophy: Assessment and Exercise-Based Treatment

Marzuca‐Nassr

SanMartín-Calísto

Guerra-Vega

et al. 2020

Advances in Experimental Medicine and Biology

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Muscle Atrophy Due to Nerve Damage Is Accompanied by Elevated Myofibrillar Protein Synthesis Rates

Cited by 30 publications

References 51 publications

Nerve damage induced skeletal muscle atrophy is associated with increased accumulation of intramuscular glucose and polyol pathway intermediates

Nerve damage induced skeletal muscle atrophy is associated with increased accumulation of intramuscular glucose and polyol pathway intermediates

Determining the contributions of protein synthesis and breakdown to muscle atrophy requires non‐steady‐state equations

Skeletal Muscle Aging Atrophy: Assessment and Exercise-Based Treatment

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