scholarly journals Targeted ablation of TRAF6 inhibits skeletal muscle wasting in mice

2010 ◽  
Vol 191 (7) ◽  
pp. 1395-1411 ◽  
Author(s):  
Pradyut K. Paul ◽  
Sanjay K. Gupta ◽  
Shephali Bhatnagar ◽  
Siva K. Panguluri ◽  
Bryant G. Darnay ◽  
...  

Skeletal muscle wasting is a major human morbidity, and contributes to mortality in a variety of clinical settings, including denervation and cancer cachexia. In this study, we demonstrate that the expression level and autoubiquitination of tumor necrosis factor (α) receptor adaptor protein 6 (TRAF6), a protein involved in receptor-mediated activation of several signaling pathways, is enhanced in skeletal muscle during atrophy. Skeletal muscle–restricted depletion of TRAF6 rescues myofibril degradation and preserves muscle fiber size and strength upon denervation. TRAF6 mediates the activation of JNK1/2, p38 mitogen-activated protein kinase, adenosine monophosphate–activated protein kinase, and nuclear factor κB, and induces the expression of muscle-specific E3 ubiquitin ligases and autophagy-related molecules in skeletal muscle upon denervation. Inhibition of TRAF6 also preserves the orderly pattern of intermyofibrillar and subsarcolemmal mitochondria in denervated muscle. Moreover, depletion of TRAF6 prevents cancer cachexia in an experimental mouse model. This study unveils a novel mechanism of skeletal muscle atrophy and suggests that TRAF6 is an important therapeutic target to prevent skeletal muscle wasting.

2020 ◽  
Vol 318 (2) ◽  
pp. R296-R310 ◽  
Author(s):  
Hélène N. Daou

Cancer cachexia is a complicated disorder of extreme, progressive skeletal muscle wasting. It is directed by metabolic alterations and systemic inflammation dysregulation. Numerous studies have demonstrated that increased systemic inflammation promotes this type of cachexia and have suggested that cytokines are implicated in the skeletal muscle loss. Exercise is firmly established as an anti-inflammatory therapy that can attenuate or even reverse the process of muscle wasting in cancer cachexia. The interleukin IL-6 is generally considered to be a key player in the development of the microenvironment of malignancy; it promotes tumor growth and metastasis by acting as a bridge between chronic inflammation and cancerous tissue and it also induces skeletal muscle atrophy and protein breakdown. Paradoxically, a beneficial role for IL-6 has also been identified recently, and that is its status as a “founding member” of the myokine class of proteins. Skeletal muscle is an important source of circulating IL-6 in people who participate in exercise training. IL-6 acts as an anti-inflammatory myokine by inhibiting TNFα and improving glucose uptake through the stimulation of AMPK signaling. This review discusses the action of IL-6 in skeletal muscle tissue dysfunction and the role of IL-6 as an “exercise factor” that modulates the immune system. This review also sheds light on the main considerations related to the treatment of muscle wasting in cancer cachexia.


2020 ◽  
Vol 21 (14) ◽  
pp. 4860 ◽  
Author(s):  
Michele Mannelli ◽  
Tania Gamberi ◽  
Francesca Magherini ◽  
Tania Fiaschi

Cachexia is a devastating pathology induced by several kinds of diseases, including cancer. The hallmark of cancer cachexia is an extended weight loss mainly due to skeletal muscle wasting and fat storage depletion from adipose tissue. The latter exerts key functions for the health of the whole organism, also through the secretion of several adipokines. These hormones induce a plethora of effects in target tissues, ranging from metabolic to differentiating ones. Conversely, the decrease of the circulating level of several adipokines positively correlates with insulin resistance, metabolic syndrome, diabetes, and cardiovascular disease. A lot of findings suggest that cancer cachexia is associated with changed secretion of adipokines by adipose tissue. In agreement, cachectic patients show often altered circulating levels of adipokines. This review reported the findings of adipokines (leptin, adiponectin, resistin, apelin, and visfatin) in cancer cachexia, highlighting that to study in-depth the involvement of these hormones in this pathology could lead to the development of new therapeutic strategies.


2020 ◽  
Vol 491 ◽  
pp. 70-77 ◽  
Author(s):  
Scott E. Mulder ◽  
Aneesha Dasgupta ◽  
Ryan J. King ◽  
Jaime Abrego ◽  
Kuldeep S. Attri ◽  
...  

2010 ◽  
Vol 188 (6) ◽  
pp. 833-849 ◽  
Author(s):  
Ashwani Mittal ◽  
Shephali Bhatnagar ◽  
Akhilesh Kumar ◽  
Estelle Lach-Trifilieff ◽  
Sandrine Wauters ◽  
...  

Skeletal muscle atrophy occurs in a variety of clinical settings, including cachexia, disuse, and denervation. Inflammatory cytokines have been shown to be mediators of cancer cachexia; however, the role of cytokines in denervation- and immobilization-induced skeletal muscle loss remains unknown. In this study, we demonstrate that a single cytokine, TNF-like weak inducer of apoptosis (TWEAK), mediates skeletal muscle atrophy that occurs under denervation conditions. Transgenic expression of TWEAK induces atrophy, fibrosis, fiber-type switching, and the degradation of muscle proteins. Importantly, genetic ablation of TWEAK decreases the loss of muscle proteins and spared fiber cross-sectional area, muscle mass, and strength after denervation. Expression of the TWEAK receptor Fn14 (fibroblast growth factor–inducible receptor 14) and not the cytokine is significantly increased in muscle upon denervation, demonstrating an unexpected inside-out signaling pathway; the receptor up-regulation allows for TWEAK activation of nuclear factor κB, causing an increase in the expression of the E3 ubiquitin ligase MuRF1. This study reveals a novel mediator of skeletal muscle atrophy and indicates that the TWEAK–Fn14 system is an important target for preventing skeletal muscle wasting.


2016 ◽  
Vol 12 (5) ◽  
pp. 4013-4020 ◽  
Author(s):  
Qiu-Lei Xi ◽  
Bo Zhang ◽  
Yi Jiang ◽  
Hai-Sheng Zhang ◽  
Qing-Yang Meng ◽  
...  

2012 ◽  
Vol 446 (1) ◽  
pp. 23-36 ◽  
Author(s):  
Sudarsanareddy Lokireddy ◽  
Isuru Wijerupage Wijesoma ◽  
Sabeera Bonala ◽  
Meng Wei ◽  
Siu Kwan Sze ◽  
...  

Humoral and tumoral factors collectively promote cancer-induced skeletal muscle wasting by increasing protein degradation. Although several humoral proteins, namely TNFα (tumour necrosis factor α) and IL (interleukin)-6, have been shown to induce skeletal muscle wasting, there is a lack of information regarding the tumoral factors that contribute to the atrophy of muscle during cancer cachexia. Therefore, in the present study, we have characterized the secretome of C26 colon cancer cells to identify the tumoral factors involved in cancer-induced skeletal muscle wasting. In the present study, we show that myostatin, a procachectic TGFβ (transforming growth factor β) superfamily member, is abundantly secreted by C26 cells. Consistent with myostatin signalling during cachexia, treating differentiated C2C12 myotubes with C26 CM (conditioned medium) resulted in myotubular atrophy due to the up-regulation of muscle-specific E3 ligases, atrogin-1 and MuRF1 (muscle RING-finger protein 1), and enhanced activity of the ubiquitin–proteasome pathway. Furthermore, the C26 CM also activated ActRIIB (activin receptor type II B)/Smad and NF-κB (nuclear factor κB) signalling, and reduced the activity of the IGF-I (insulin-like growth factor 1)/PI3K (phosphoinositide 3-kinase)/Akt pathway, three salient molecular features of myostatin action in skeletal muscles. Antagonists to myostatin prevented C26 CM-induced wasting in muscle cell cultures, further confirming that tumoral myostatin may be a key contributor in the pathogenesis of cancer cachexia. Finally, we show that treatment with C26 CM induced the autophagy–lysosome pathway and reduced the number of mitochondria in myotubes. These two previously unreported observations were recapitulated in skeletal muscles collected from C26 tumour-bearing mice.


2021 ◽  
Author(s):  
Ji-Hyung Lee ◽  
Seon-Wook Kim ◽  
Jun-Hyeong Kim ◽  
Hyung-Jun Kim ◽  
JungIn Um ◽  
...  

Abstract Inflammation-mediated skeletal muscle wasting is induced by inflammatory cytokines. It occurs in critically ill patients with sepsis (termed intensive care unit acquired weakness) and patients with advanced metastasis (termed cancer cachexia). Both conditions severely impact on patient morbidity and mortality. Lithium chloride has been investigated as a drug repurposing candidate for numerous diseases. In this study, we assessed whether lithium chloride affects inflammation-mediated muscle wasting, using in vitro and in vivo models of cancer cachexia and sepsis. Lithium chloride prevented wasting in myotubes cultured with cancer cell conditioned media, maintained expression of the muscle fiber contractile protein, myosin heavy chain 2 and blocked upregulation of the E3 ubiquitin ligase, Atrogin-1. Glycogen synthase kinase-3β inhibition was indicated as the target mechanism, due to the following observations: 1) β-catenin was upregulated in the myotubes and 2) inhibition of IMPA1, the secondary biological target of lithium chloride, did not inhibit the effects of cancer conditioned media. Lithium chloride inhibited upregulation of the inflammation-associated cytokines Il-1β, Il-6 and inos in macrophages treated with lipopolysaccharide. Lithium chloride treatment in an animal model of sepsis improved body weight, increased muscle mass, preserved the survival of larger fibers and decreased expression of the wasting effector genes, Atrogin-1 and Murf-1. In a model of cancer cachexia, lithium chloride increased muscle mass, enhanced muscle strength and increased fiber cross sectional area, with no significant effect on tumorigenesis. These results indicate that lithium chloride could be repurposed as a drug to treat patients with inflammation-mediated skeletal muscle wasting.


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