Attenuation of skeletal muscle atrophy via protease inhibition

2005 ◽  
Vol 99 (5) ◽  
pp. 1719-1727 ◽  
Author(s):  
Carl A. Morris ◽  
Linda D. Morris ◽  
Ann R. Kennedy ◽  
H. Lee Sweeney

Skeletal muscle atrophy in response to a number of muscle wasting conditions, including disuse, involves the induction of increased protein breakdown, decreased protein synthesis, and likely a variable component of apoptosis. The increased activation of specific proteases in the atrophy process presents a number of potential therapeutic targets to reduce muscle atrophy via protease inhibition. In this study, mice were provided with food supplemented with the Bowman-Birk inhibitor (BBI), a serine protease inhibitor known to reduce the proteolytic activity of a number of proteases, such as chymotrypsin, trypsin, elastase, cathepsin G, and chymase. Mice fed the BBI diet were suspended for 3–14 days, and the muscle mass and function were then compared with those of the suspended mice on a normal diet. The results indicate that dietary supplementation with BBI significantly attenuates the normal loss of muscle mass and strength following unloading. Furthermore, the data reveal the existence of yet uncharacterized serine proteases that are important contributors to the evolution of disuse atrophy, since BBI inhibited serine protease activity that was elevated following hindlimb unloading and also slowed the loss of muscle fiber size. These results demonstrate that targeted reduction of protein degradation can limit the severity of muscle mass loss following hindlimb unloading. Thus BBI is a candidate therapeutic agent to minimize skeletal muscle atrophy and loss of strength associated with disuse, cachexia, sepsis, weightlessness, or the combination of age and inactivity.

2014 ◽  
Vol 306 (8) ◽  
pp. C762-C767 ◽  
Author(s):  
Chia-Ling Wu ◽  
Evangeline W. Cornwell ◽  
Robert W. Jackman ◽  
Susan C. Kandarian

The muscle-specific ring finger protein 1 (MuRF1) gene is required for most types of skeletal muscle atrophy yet we have little understanding of its transcriptional regulation. The purpose of this study is to identify whether NF-κB and/or FoxO response elements in the MuRF1 promoter are required for MuRF1 gene activation during skeletal muscle atrophy due to the removal of hindlimb weight bearing (“unloading”). Both NF-κB -dependent and FoxO-dependent luciferase reporter activities were significantly increased at 5 days of unloading. Using a 4.4-kb MuRF1 promoter reporter construct, a fourfold increase in reporter (i.e., luciferase) activity was found in rat soleus muscles after 5 days of hindlimb unloading. This activation was abolished by mutagenesis of either of the two distal putative NF-κB sites or all three putative NF-κB sites but not by mutagenesis of all four putative FoxO sites. This work provides the first direct evidence that NF-κB sites, but not FoxO sites, are required for MuRF1 promoter activation in muscle disuse atrophy in vivo.


2021 ◽  
Vol 37 (1) ◽  
Author(s):  
Akira Nemoto ◽  
Toru Goyagi

Abstract Background Sarcopenia promotes skeletal muscle atrophy and exhibits a high mortality rate. Its elucidation is of the highest clinical importance, but an animal experimental model remains controversial. In this study, we investigated a simple method for studying sarcopenia in rats. Results Muscle atrophy was investigated in 24-week-old, male, tail-suspended (TS), Sprague Dawley and spontaneously hypertensive rats (SHR). Age-matched SD rats were used as a control group. The skeletal muscle mass weight, muscle contraction, whole body tension (WBT), cross-sectional area (CSA), and Muscle RING finger-1 (MuRF-1) were assessed. Enzyme-linked immunosorbent assay was used to evaluate the MuRF-1 levels. Two muscles, the extensor digitorum longus and soleus muscles, were selected for representing fast and slow muscles, respectively. All data, except CSA, were analyzed by a one-way analysis of variance, whereas CSA was analyzed using the Kruskal-Wallis test. Muscle mass weight, muscle contraction, WBT, and CSA were significantly lower in the SHR (n = 7) and TS (n = 7) groups than in the control group, whereas MuRF-1 expression was dominant. Conclusions TS and SHR presented sarcopenic phenotypes in terms of muscle mass, muscle contraction and CSA. TS is a useful technique for providing muscle mass atrophy and weakness in an experimental model of sarcopenia in rats.


2020 ◽  
Vol 21 (5) ◽  
pp. 1628 ◽  
Author(s):  
Keisuke Hitachi ◽  
Masashi Nakatani ◽  
Shiori Funasaki ◽  
Ikumi Hijikata ◽  
Mizuki Maekawa ◽  
...  

Skeletal muscle is a highly plastic organ that is necessary for homeostasis and health of the human body. The size of skeletal muscle changes in response to intrinsic and extrinsic stimuli. Although protein-coding RNAs including myostatin, NF-κβ, and insulin-like growth factor-1 (IGF-1), have pivotal roles in determining the skeletal muscle mass, the role of long non-coding RNAs (lncRNAs) in the regulation of skeletal muscle mass remains to be elucidated. Here, we performed expression profiling of nine skeletal muscle differentiation-related lncRNAs (DRR, DUM1, linc-MD1, linc-YY1, LncMyod, Neat1, Myoparr, Malat1, and SRA) and three genomic imprinting-related lncRNAs (Gtl2, H19, and IG-DMR) in mouse skeletal muscle. The expression levels of these lncRNAs were examined by quantitative RT-PCR in six skeletal muscle atrophy models (denervation, casting, tail suspension, dexamethasone-administration, cancer cachexia, and fasting) and two skeletal muscle hypertrophy models (mechanical overload and deficiency of the myostatin gene). Cluster analyses of these lncRNA expression levels were successfully used to categorize the muscle atrophy models into two sub-groups. In addition, the expression of Gtl2, IG-DMR, and DUM1 was altered along with changes in the skeletal muscle size. The overview of the expression levels of lncRNAs in multiple muscle atrophy and hypertrophy models provides a novel insight into the role of lncRNAs in determining the skeletal muscle mass.


2015 ◽  
Vol 36 (6) ◽  
pp. 405-421 ◽  
Author(s):  
C. J. Malavaki ◽  
G. K. Sakkas ◽  
G. I. Mitrou ◽  
A. Kalyva ◽  
I. Stefanidis ◽  
...  

2001 ◽  
Vol 281 (1) ◽  
pp. C179-C187 ◽  
Author(s):  
Troy A. Hornberger ◽  
R. Bridge Hunter ◽  
Susan C. Kandarian ◽  
Karyn A. Esser

In the rat, denervation and hindlimb unloading are two commonly employed models used to study skeletal muscle atrophy. In these models, muscle atrophy is generally produced by a decrease in protein synthesis and an increase in protein degradation. The decrease in protein synthesis has been suggested to occur by an inhibition at the level of protein translation. To better characterize the regulation of protein translation, we investigated the changes that occur in various translation initiation and elongation factors. We demonstrated that both hindlimb unloading and denervation produce alterations in the phosphorylation and/or total amount of the 70-kDa ribosomal S6 kinase, eukaryotic initiation factor 2 α-subunit, and eukaryotic elongation factor 2. Our findings indicate that the regulation of these protein translation factors differs between the models of atrophy studied and between the muscles evaluated (e.g., soleus vs. extensor digitorum longus).


Nutrients ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 2180
Author(s):  
Mari Noguchi ◽  
Tomoya Kitakaze ◽  
Yasuyuki Kobayashi ◽  
Katsuyuki Mukai ◽  
Naoki Harada ◽  
...  

We investigated the effects of β-cryptoxanthin on skeletal muscle atrophy in senescence-accelerated mouse-prone 1 (SAMP1) mice. For 15 weeks, SAMP1 mice were intragastrically administered vehicle or β-cryptoxanthin. At 35 weeks of age, the skeletal muscle mass in SAMP1 mice was reduced compared with that in control senescence-accelerated mouse-resistant 1 (SAMR1) mice. β-cryptoxanthin increased muscle mass with an increase in the size of muscle fibers in the soleus muscle of SAMP1 mice. The expressions of autophagy-related factors such as beclin-1, p62, LC3-I, and LC3-II were increased in the soleus muscle of SAMP1 mice; however, β-cryptoxanthin administration inhibited this increase. Unlike in SAMR1 mice, p62 was punctately distributed throughout the cytosol in the soleus muscle fibers of SAMP1 mice; however, β-cryptoxanthin inhibited this punctate distribution. The cross-sectional area of p62-positive fiber was smaller than that of p62-negative fiber, and the ratio of p62-positive fibers to p62-negative fibers was increased in SAMP1 mice. β-cryptoxanthin decreased this ratio in SAMP1 mice. Furthermore, β-cryptoxanthin decreased the autophagy-related factor expression in murine C2C12 myotube. The autophagy inhibitor bafilomycin A1, but not the proteasome inhibitor MG132, inhibited the β-cryptoxanthin-induced decrease in p62 and LC3-II expressions. These results indicate that β-cryptoxanthin inhibits the p62 accumulation in fibers and improves muscle atrophy in the soleus muscle of SAMP1 mice.


Author(s):  
Tom Tanjeko Ajime ◽  
Jef Serré ◽  
Rob C I Wüst ◽  
Guy Anselme Mpaka Messa ◽  
Chiel Poffé ◽  
...  

Abstract Introduction Apart from its adverse effects on the respiratory system, cigarette smoking also induces skeletal muscle atrophy and dysfunction. Whether short-term smoking cessation can restore muscle mass and function is unknown. We, therefore, studied the impact of 1- and 2-week smoking cessation on skeletal muscles in a mouse model. Methods Male mice were divided into four groups: Air-exposed (14 weeks); cigarette smoke (CS)-exposed (14 weeks); CS-exposed (13 weeks) followed by 1-week cessation; CS-exposed (12 weeks) followed by 2 weeks cessation to examine exercise capacity, physical activity levels, body composition, muscle function, capillarization, mitochondrial function and protein expression in the soleus, plantaris, and diaphragm muscles. Results CS-induced loss of body and muscle mass was significantly improved within 1 week of cessation due to increased lean and fat mass. Mitochondrial respiration and protein levels of the respiratory complexes in the soleus were lower in CS-exposed mice, but similar to control values after 2 weeks of cessation. Exposing isolated soleus muscles to CS extracts reduced mitochondrial respiration that was reversed after removing the extract. While physical activity was reduced in all groups, exercise capacity, limb muscle force, fatigue resistance, fiber size and capillarization, and diaphragm cytoplasmic HIF-1α were unaltered by CS-exposure. However, CS-induced diaphragm atrophy and increased capillary density were not seen after 2 weeks of smoking cessation. Conclusion In male mice, 2 weeks of smoking cessation reversed smoking-induced mitochondrial dysfunction, limb muscle mass loss, and diaphragm muscle atrophy, highlighting immediate benefits of cessation on skeletal muscles. Implications Our study demonstrates that CS-induced skeletal muscle mitochondrial dysfunction and atrophy are significantly improved by 2 weeks of cessation in male mice. We show for the first time that smoking cessation as short as 1 to 2 weeks is associated with immediate beneficial effects on skeletal muscle structure and function with the diaphragm being particularly sensitive to CS-exposure and cessation. This could help motivate smokers to quit smoking as early as possible. The knowledge that smoking cessation has potential positive extrapulmonary effects is particularly relevant for patients referred to rehabilitation programs and those admitted to hospitals suffering from acute or chronic muscle deterioration yet struggling with smoking cessation.


Nutrients ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 2274
Author(s):  
Roi Cal ◽  
Heidi Davis ◽  
Alish Kerr ◽  
Audrey Wall ◽  
Brendan Molloy ◽  
...  

Skeletal muscle is the metabolic powerhouse of the body, however, dysregulation of the mechanisms involved in skeletal muscle mass maintenance can have devastating effects leading to many metabolic and physiological diseases. The lack of effective solutions makes finding a validated nutritional intervention an urgent unmet medical need. In vitro testing in murine skeletal muscle cells and human macrophages was carried out to determine the effect of a hydrolysate derived from vicia faba (PeptiStrong: NPN_1) against phosphorylated S6, atrophy gene expression, and tumour necrosis factor alpha (TNF-α) secretion, respectively. Finally, the efficacy of NPN_1 on attenuating muscle waste in vivo was assessed in an atrophy murine model. Treatment of NPN_1 significantly increased the phosphorylation of S6, downregulated muscle atrophy related genes, and reduced lipopolysaccharide-induced TNF-α release in vitro. In a disuse atrophy murine model, following 18 days of NPN_1 treatment, mice exhibited a significant attenuation of muscle loss in the soleus muscle and increased the integrated expression of Type I and Type IIa fibres. At the RNA level, a significant upregulation of protein synthesis-related genes was observed in the soleus muscle following NPN_1 treatment. In vitro and preclinical results suggest that NPN_1 is an effective bioactive ingredient with great potential to prolong muscle health.


2020 ◽  
Vol 21 (18) ◽  
pp. 6663 ◽  
Author(s):  
Dulce Peris-Moreno ◽  
Daniel Taillandier ◽  
Cécile Polge

The E3 ubiquitin ligase MuRF1/TRIM63 was identified 20 years ago and suspected to play important roles during skeletal muscle atrophy. Since then, numerous studies have been conducted to decipher the roles, molecular mechanisms and regulation of this enzyme. This revealed that MuRF1 is an important player in the skeletal muscle atrophy process occurring during catabolic states, making MuRF1 a prime candidate for pharmacological treatments against muscle wasting. Indeed, muscle wasting is an associated event of several diseases (e.g., cancer, sepsis, diabetes, renal failure, etc.) and negatively impacts the prognosis of patients, which has stimulated the search for MuRF1 inhibitory molecules. However, studies on MuRF1 cardiac functions revealed that MuRF1 is also cardioprotective, revealing a yin and yang role of MuRF1, being detrimental in skeletal muscle and beneficial in the heart. This review discusses data obtained on MuRF1, both in skeletal and cardiac muscles, over the past 20 years, regarding the structure, the regulation, the location and the different functions identified, and the first inhibitors reported, and aim to draw the picture of what is known about MuRF1. The review also discusses important MuRF1 characteristics to consider for the design of future drugs to maintain skeletal muscle mass in patients with different pathologies.


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