Skeletal Muscle Anti-Atrophic Effects of Leucine Involve Myostatin Inhibition

e15633 Background: Almost half of cancer deaths are attributed to cancers most frequently associated with cachexia. Cachexia is a complex metabolic disease characterized by anorexia and unintentional weight loss. Skeletal muscle depletion has been recognized as a key feature of the disease, however muscle anabolic therapies have not been successful, suggesting that treatments that target multiple aspects of the disease will be most effective. Growth differentiation factor 15 (GDF-15) is a cytokine that induces anorexia and weight loss and is associated with cachexia in cancer patients. In preclinical cancer cachexia models, GDF-15 inhibition is sufficient to normalize food intake and body weight, including skeletal muscle mass. However, it remains to be determined whether the increased skeletal muscle mass also results in restoration of muscle function. Therefore, we examined the effect of GDF-15 inhibition on muscle mass and function in mouse models of cancer cachexia in comparison with myostatin inhibition, an established muscle anabolic pathway. Methods: Cachectic mouse tumor models were established with subcutaneous implantation of tumor cell lines reported to be GDF-15-dependent; mouse renal cell carcinoma (RENCA) and human ovarian cancer (TOV-21G) cell lines. Mice were treated with anti-GDF-15 (mAB2) or anti-myostatin (RK35) monoclonal antibodies and skeletal muscle function was assessed in vivo via maximum force, maximum rate of contraction and half relax time. In the RENCA tumor model, GDF-15 inhibition fully restored body weight and skeletal muscle mass whereas myostatin inhibition showed only a modest effect. Results: Consistent with the muscle mass improvement, GDF-15 inhibition dramatically increased functional muscle endpoints compared to the partial effect of myostatin inhibition. Interestingly, in the TOV-21G tumor model GDF-15 inhibition only partially restored body weight, however skeletal muscle mass and muscle function were completely normalized. Consistent with the functional assessment, GDF-15 inhibition in the RENCA tumor model decreased the expression of several catabolic genes (i.e. Trim63, Fbxo32, Myh7 and Myh2). The GDF-15 effect is likely to be secondary to the reversal of anorexia since wildtype mice pair-fed to Fc-GDF-15-treated mice demonstrated equivalent muscle mass loss. Conclusions: Taken together these data suggest that GDF-15 inhibition holds potential as an effective therapeutic approach to alleviate multiple aspects of cachexia.

Download Full-text

Antibody‐directed myostatin inhibition in 21‐mo‐old mice reveals novel roles for myostatin signaling in skeletal muscle structure and function

The FASEB Journal ◽

10.1096/fj.10-159608 ◽

2010 ◽

Vol 24 (11) ◽

pp. 4433-4442 ◽

Cited By ~ 88

Author(s):

Kate T. Murphy ◽

René Koopman ◽

Timur Naim ◽

Bertrand Léger ◽

Jennifer Trieu ◽

...

Keyword(s):

Skeletal Muscle ◽

Structure And Function ◽

Muscle Structure ◽

Myostatin Inhibition ◽

And Function ◽

Old Mice

Download Full-text

p21-Activated Kinase 1 Is Permissive for the Skeletal Muscle Hypertrophy Induced by Myostatin Inhibition

Frontiers in Physiology ◽

10.3389/fphys.2021.677746 ◽

2021 ◽

Vol 12 ◽

Author(s):

Caroline Barbé ◽

Audrey Loumaye ◽

Pascale Lause ◽

Olli Ritvos ◽

Jean-Paul Thissen

Keyword(s):

Skeletal Muscle ◽

Muscle Mass ◽

Skeletal Muscle Mass ◽

Muscle Hypertrophy ◽

Molecular Mechanisms ◽

Muscle Development ◽

The Body ◽

Negative Regulator ◽

Skeletal Muscle Hypertrophy ◽

Myostatin Inhibition

Skeletal muscle, the most abundant tissue in the body, plays vital roles in locomotion and metabolism. Understanding the cellular processes that govern regulation of muscle mass and function represents an essential step in the development of therapeutic strategies for muscular disorders. Myostatin, a member of the TGF-β family, has been identified as a negative regulator of muscle development. Indeed, its inhibition induces an extensive skeletal muscle hypertrophy requiring the activation of Smad 1/5/8 and the Insulin/IGF-I signaling pathway, but whether other molecular mechanisms are involved in this process remains to be determined. Using transcriptomic data from various Myostatin inhibition models, we identified Pak1 as a potential mediator of Myostatin action on skeletal muscle mass. Our results show that muscle PAK1 levels are systematically increased in response to Myostatin inhibition, parallel to skeletal muscle mass, regardless of the Myostatin inhibition model. Using Pak1 knockout mice, we investigated the role of Pak1 in the skeletal muscle hypertrophy induced by different approaches of Myostatin inhibition. Our findings show that Pak1 deletion does not impede the skeletal muscle hypertrophy magnitude in response to Myostatin inhibition. Therefore, Pak1 is permissive for the skeletal muscle mass increase caused by Myostatin inhibition.

Download Full-text

Myostatin Inhibition Using ActRIIB-mFc Does Not Produce Weight Gain or Strength in the Nebulin Conditional KO Mouse

Journal of Neuropathology & Experimental Neurology ◽

10.1093/jnen/nly120 ◽

2018 ◽

Vol 78 (2) ◽

pp. 130-139 ◽

Cited By ~ 3

Author(s):

Jennifer A Tinklenberg ◽

Emily M Siebers ◽

Margaret J Beatka ◽

Brittany A Fickau ◽

Samuel Ayres ◽

...

Keyword(s):

Skeletal Muscle ◽

Weight Gain ◽

Mouse Model ◽

Mouse Models ◽

Clinical Symptoms ◽

Conditional Knockout ◽

Variable Degree ◽

Pathological Changes ◽

Myostatin Inhibition ◽

Nemaline Bodies

Abstract Mutations in at least 12 genes are responsible for a group of congenital skeletal muscle diseases known as nemaline myopathies (NMs). NMs are associated with a range of clinical symptoms and pathological changes often including the presence of cytoplasmic rod-like structures (nemaline bodies) and myofiber hypotrophy. Our recent work has identified a variable degree of behavioral benefit when treating 2 NM mouse models due to mutations in Acta1 with myostatin inhibition. This study is focused on the effects of delivering ActRIIB-mFc (Acceleron; a myostatin inhibitor) to the nebulin conditional knockout KO (Neb cKO) mouse model of NM. Treatment of Neb cKO mice with ActRIIB-mFc did not produce increases in weight gain, strength, myofiber size, or hypertrophic pathway signaling. Overall, our studies demonstrate a lack of response in Neb cKO mice to myostatin inhibition, which differs from the response observed when treating other NM models.

Download Full-text

Myostatin Inhibition Attenuates T3‐induced Skeletal Muscle Atrophy

The FASEB Journal ◽

10.1096/fasebj.2020.34.s1.09602 ◽

2020 ◽

Vol 34 (S1) ◽

pp. 1-1

Author(s):

André Cruz ◽

William Jose da Silva ◽

Anselmo Sigari Moriscot

Keyword(s):

Skeletal Muscle ◽

Muscle Atrophy ◽

Skeletal Muscle Atrophy ◽

Myostatin Inhibition

Download Full-text

Enhanced Muscle Growth by Plasmid-Mediated Delivery of Myostatin Propeptide

Journal of Biomedicine and Biotechnology ◽

10.1155/2010/862591 ◽

2010 ◽

Vol 2010 ◽

pp. 1-8 ◽

Cited By ~ 11

Author(s):

Shengwei Hu ◽

Chuangfu Chen ◽

Jingliang Sheng ◽

Yufang Sun ◽

Xudong Cao ◽

...

Keyword(s):

Skeletal Muscle ◽

Transforming Growth Factor Beta ◽

Muscle Development ◽

Transforming Growth Factor ◽

Genetic Manipulation ◽

Muscle Growth ◽

Negative Regulator ◽

Dna Encoding ◽

Single Intramuscular Injection ◽

Myostatin Inhibition

Myostatin is a member of the transforming growth factor beta (TGF-β) superfamily that functions as a negative regulator of skeletal muscle development and growth. Myostatin blockade therefore offers a strategy for promoting muscle growth in livestock production without resorting to genetic manipulation. In this report, we examined the effect of myostatin inhibition by plasmid-mediated delivery of a mutant myostatin propeptide (MProD76A), a natural inhibitor of myostatin, on the growth performance of mice. A significant increase in skeletal muscle mass was observed after a single intramuscular injection of naked plasmid DNA encoding MProD76A into mice. Enhanced muscle growth occurred because of myofiber hypertrophy, but no cardiac muscle hypertrophy and organomegaly was observed in the mice after myostatin inhibition by plasmid-mediated MProD76A delivery. These results demonstrate a promising approach to enhancing muscle growth that warrants further investigation in domestic animals.

Download Full-text

The Type 1 Insulin-Like Growth Factor Receptor (IGF-IR) Pathway Is Mandatory for the Follistatin-Induced Skeletal Muscle Hypertrophy

Endocrinology ◽

10.1210/en.2011-1687 ◽

2012 ◽

Vol 153 (1) ◽

pp. 241-253 ◽

Cited By ~ 33

Author(s):

S. Kalista ◽

O. Schakman ◽

H. Gilson ◽

P. Lause ◽

B. Demeulder ◽

...

Keyword(s):

Skeletal Muscle ◽

Knockout Mice ◽

Muscle Hypertrophy ◽

Critical Role ◽

Muscle Growth ◽

Dominant Negative ◽

Wild Type ◽

Myostatin Inhibition

Myostatin inhibition by follistatin (FS) offers a new approach for muscle mass enhancement. The aim of the present study was to characterize the mediators responsible for the FS hypertrophic action on skeletal muscle in male mice. Because IGF-I and IGF-II, two crucial skeletal muscle growth factors, are induced by myostatin inhibition, we assessed their role in FS action. First, we tested whether type 1 IGF receptor (IGF-IR) is required for FS-induced hypertrophy. By using mice expressing a dominant-negative IGF-IR in skeletal muscle, we showed that IGF-IR inhibition blunted by 63% fiber hypertrophy caused by FS. Second, we showed that FS caused the same degree of fiber hypertrophy in wild-type and IGF-II knockout mice. We then tested the role of the signaling molecules stimulated by IGF-IR, in particular the Akt/mammalian target of rapamycin (mTOR)/70-kDa ribosomal protein S6 kinase (S6K) pathway. We investigated whether Akt phosphorylation is required for the FS action. By cotransfecting a dominant-negative form of Akt together with FS, we showed that Akt inhibition reduced by 65% fiber hypertrophy caused by FS. Second, we evaluated the role of mTOR in FS action. Fiber hypertrophy induced by FS was reduced by 36% in rapamycin-treated mice. Finally, because the activity of S6K is increased by FS, we tested its role in FS action. FS caused the same degree of fiber hypertrophy in wild-type and S6K1/2 knockout mice. In conclusion, the IGF-IR/Akt/mTOR pathway plays a critical role in FS-induced muscle hypertrophy. In contrast, induction of IGF-II expression and S6K activity by FS are not required for the hypertrophic action of FS.

Download Full-text

Antibody-directed myostatin inhibition enhances muscle mass and function in tumor-bearing mice

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00121.2011 ◽

2011 ◽

Vol 301 (3) ◽

pp. R716-R726 ◽

Cited By ~ 58

Author(s):

Kate T. Murphy ◽

Annabel Chee ◽

Ben G. Gleeson ◽

Timur Naim ◽

Kristy Swiderski ◽

...

Keyword(s):

Skeletal Muscle ◽

Muscle Mass ◽

Muscle Atrophy ◽

Cancer Cachexia ◽

Diaphragm Muscle ◽

Oxidative Enzymes ◽

Saline Control ◽

Tumor Bearing ◽

Myostatin Inhibition ◽

And Function

Cancer cachexia describes the progressive skeletal muscle wasting and weakness in many cancer patients and accounts for >20% of cancer-related deaths. We tested the hypothesis that antibody-directed myostatin inhibition would attenuate the atrophy and loss of function in muscles of tumor-bearing mice. Twelve-week-old C57BL/6 mice received a subcutaneous injection of saline (control) or Lewis lung carcinoma (LLC) tumor cells. One week later, mice received either once weekly injections of saline (control, n = 12; LLC, n = 9) or a mouse chimera of anti-human myostatin antibody (PF-354, 10 mg·kg−1·wk−1, LLC+PF-354, n = 11) for 5 wk. Injection of LLC cells reduced muscle mass and maximum force of tibialis anterior (TA) muscles by 8–10% ( P < 0.05), but the muscle atrophy and weakness were prevented with PF-354 treatment ( P > 0.05). Maximum specific (normalized) force of diaphragm muscle strips was reduced with LLC injection ( P < 0.05) but was not improved with PF-354 treatment ( P > 0.05). PF-354 enhanced activity of oxidative enzymes in TA and diaphragm muscles of tumor-bearing mice by 118% and 89%, respectively ( P < 0.05). Compared with controls, apoptosis that was not of myofibrillar or satellite cell origin was 140% higher in TA muscle cross sections from saline-treated LLC tumor-bearing mice ( P < 0.05) but was not different in PF-354-treated tumor-bearing mice ( P > 0.05). Antibody-directed myostatin inhibition attenuated the skeletal muscle atrophy and loss of muscle force-producing capacity in a murine model of cancer cachexia, in part by reducing apoptosis. The improvements in limb muscle mass and function highlight the therapeutic potential of antibody-directed myostatin inhibition for cancer cachexia.

Download Full-text

Local myostatin inhibition improves skeletal muscle glucose uptake in insulin-resistant high-fat diet-fed mice

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00185.2019 ◽

2020 ◽

Vol 319 (1) ◽

pp. E163-E174

Author(s):

Wouter Eilers ◽

David Chambers ◽

Mark Cleasby ◽

Keith Foster

Keyword(s):

Skeletal Muscle ◽

Glucose Uptake ◽

High Fat Diet ◽

Muscle Hypertrophy ◽

Glucose Transporter ◽

Whole Body ◽

Glucose Disposal ◽

Peroxisome Proliferator ◽

High Fat ◽

Myostatin Inhibition

Myostatin inhibition is thought to improve whole body insulin sensitivity and mitigate the development of insulin resistance in models of obesity. However, although myostatin is known to be a major regulator of skeletal muscle mass, the direct effects of myostatin inhibition in muscle on glucose uptake and the mechanisms that may underlie this are still unclear. We investigated the effect of local myostatin inhibition by adeno-associated virus-mediated overexpression of the myostatin propeptide on insulin-stimulated skeletal muscle glucose disposal in chow-fed or high fat diet-fed mice and evaluated the molecular pathways that might mediate this. We found that myostatin inhibition improved glucose disposal in obese high fat diet-fed mice alongside the induction of muscle hypertrophy but did not have an impact in chow-fed mice. This improvement was not associated with greater glucose transporter or peroxisome proliferator-activated receptor-γ coactivator-1α expression or 5′ AMP-activated protein kinase activation as previously suggested. Instead, transcriptomic analysis suggested that the improvement in glucose disposal was associated with significant enrichment in genes involved in fatty acid metabolism and translation of mitochondrial genes. Thus, myostatin inhibition improves muscle insulin-stimulated glucose disposal in obese high fat diet-fed mice independent of muscle hypertrophy, potentially involving previously unidentified pathways.

Download Full-text