Myostatin promotes the wasting of human myoblast cultures through promoting ubiquitin-proteasome pathway-mediated loss of sarcomeric proteins

2011 ◽  
Vol 301 (6) ◽  
pp. C1316-C1324 ◽  
Author(s):  
Sudarsanareddy Lokireddy ◽  
Vincent Mouly ◽  
Gillian Butler-Browne ◽  
Peter D. Gluckman ◽  
Mridula Sharma ◽  
...  

Myostatin is a negative regulator of skeletal muscle growth and in fact acts as a potent inducer of “cachectic-like” muscle wasting in mice. The mechanism of action of myostatin in promoting muscle wasting has been predominantly studied in murine models. Despite numerous reports linking elevated levels of myostatin to human skeletal muscle wasting conditions, little is currently known about the signaling mechanism(s) through which myostatin promotes human skeletal muscle wasting. Therefore, in this present study we describe in further detail the mechanisms behind myostatin regulation of human skeletal muscle wasting using an in vitro human primary myotube atrophy model. Treatment of human myotube populations with myostatin promoted dramatic myotubular atrophy. Mechanistically, myostatin-induced myotube atrophy resulted in reduced p-AKT concomitant with the accumulation of active dephosphorylated Forkhead Box-O (FOXO1) and FOXO3. We further show that addition of myostatin results in enhanced activation of atrogin-1 and muscle-specific RING finger protein 1 (MURF1) and reduced expression of both myosin light chain (MYL) and myosin heavy chain (MYH). In addition, we found that myostatin-induced loss of MYL and MYH proteins is dependent on the activity of the proteasome and mediated via SMAD3-dependent regulation of FOXO1 and atrogin-1. Therefore, these data suggest that the mechanism through which myostatin promotes muscle wasting is very well conserved between species, and that myostatin-induced human myotube atrophy is mediated through inhibition of insulin-like growth factor (IGF)/phosphoinositide 3-kinase (PI3-K)/AKT signaling and enhanced activation of the ubiquitin-proteasome pathway and elevated protein degradation.

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Johanna Abrigo ◽  
Juan Carlos Rivera ◽  
Javier Aravena ◽  
Daniel Cabrera ◽  
Felipe Simon ◽  
...  

Obesity can lead to skeletal muscle atrophy, a pathological condition characterized by the loss of strength and muscle mass. A feature of muscle atrophy is a decrease of myofibrillar proteins as a result of ubiquitin proteasome pathway overactivation, as evidenced by increased expression of the muscle-specific ubiquitin ligases atrogin-1 and MuRF-1. Additionally, other mechanisms are related to muscle wasting, including oxidative stress, myonuclear apoptosis, and autophagy. Stem cells are an emerging therapy in the treatment of chronic diseases such as high fat diet-induced obesity. Mesenchymal stem cells (MSCs) are a population of self-renewable and undifferentiated cells present in the bone marrow and other mesenchymal tissues of adult individuals. The present study is the first to analyze the effects of systemic MSC administration on high fat diet-induced skeletal muscle atrophy in the tibialis anterior of mice. Treatment with MSCs reduced losses of muscle strength and mass, decreases of fiber diameter and myosin heavy chain protein levels, and fiber type transitions. Underlying these antiatrophic effects, MSC administration also decreased ubiquitin proteasome pathway activation, oxidative stress, and myonuclear apoptosis. These results are the first to indicate that systemically administered MSCs could prevent muscle wasting associated with high fat diet-induced obesity and diabetes.


2002 ◽  
Vol 102 (3) ◽  
pp. 353-361 ◽  
Author(s):  
R. Thomas JAGOE ◽  
Christopher P.F. REDFERN ◽  
Russell G. ROBERTS ◽  
G. John GIBSON ◽  
Timothy H.J. GOODSHIP

Muscle wasting is a common and prominent feature of advanced cancer, including lung cancer. Evidence from animal experiments suggests that accelerated proteolysis via the ubiquitin-proteasome pathway is the primary cause of cancer-related cachexia. However, there are few data on the role of this pathway in determining muscle wasting in human cancer. The present study was designed to measure whether skeletal muscle gene expression of components of the ubiquitin-proteasome pathway and/or the lysosomal proteolytic pathway was increased in patients with early lung cancer. A total of 36 patients with lung cancer referred for curative resection and 10 control subjects had biopsies of latissimus dorsi muscle taken at operation. mRNA levels of four components of the ubiquitin-proteasome pathway, i.e. polyubiquitin, C2α proteasome subunit, 14kDa ubiquitin-carrier protein and ubiquitin-activating protein, and of two lysosomal proteolytic enzymes, i.e. cathepsin B and cathepsin D, were measured using quantitative Northern blotting. mRNA levels for cathepsin B, but not for components of the ubiquitin-proteasome pathway, were higher in patients with cancer compared with controls (P = 0.01). Among lung cancer patients, cathepsin B mRNA levels correlated with fat-free mass index (r =-0.57, P = 0.003) and tumour stage (rs = 0.45, P = 0.03), and were higher in smokers (P = 0.04). Thus gene expression of the lysosomal protease cathepsin B is increased in the skeletal muscle of patients with early lung cancer, and the strong inverse relationship with fat-free mass suggests that cathepsin B may have a role in inducing muscle wasting in the early stages of lung cancer.


2005 ◽  
Vol 41 (1) ◽  
pp. 173 ◽  
Author(s):  
Didier Attaix ◽  
Sophie Ventadour ◽  
Audrey Codran ◽  
Daniel Béchet ◽  
Daniel Taillandier ◽  
...  

2006 ◽  
Vol 20 (9) ◽  
pp. 1531-1533 ◽  
Author(s):  
Xun Wang ◽  
Gregory H. Hockerman ◽  
Henry W. Green ◽  
Charles F. Babbs ◽  
Sulma I. Mohammad ◽  
...  

Author(s):  
Jorne Ubachs ◽  
Wouter R.P.H. Worp ◽  
Rianne D.W. Vaes ◽  
Kenneth Pasmans ◽  
Ramon C. Langen ◽  
...  

2017 ◽  
Vol 37 (suppl_1) ◽  
Author(s):  
Kellie R Machlus ◽  
Prakrith Vijey ◽  
Thomas Soussou ◽  
Joseph E Italiano

Background: Proteasome inhibitors such as bortezomib, a chemotherapeutic used to treat multiple myeloma, induce thrombocytopenia within days of initiation. The mechanism for this thrombocytopenia has been tied to data revealing that proteasome activity is essential for platelet formation. The major pathway of selective protein degradation uses ubiquitin as a marker that targets proteins for proteolysis by the proteasome. This pathway is previously unexplored in megakaryocytes (MKs). Objectives: We aim to define the mechanism by which the ubiquitin-proteasome pathway affects MK maturation and platelet production. Results: Pharmacologic inhibition of proteasome activity blocks proplatelet formation in megakaryocytes. To further characterize how this degradation was occurring, we probed distinct ubiquitin pathways. Inhibition of the ubiquitin-activating enzyme E1 significantly inhibited proplatelet formation up to 73%. In addition, inhibition of the deubiquitinase proteins UCHL5 and USP14 significantly inhibited proplatelet formation up to 83%. These data suggest that an intact ubiquitin pathway is necessary for proplatelet formation. Proteomic and polysome analyses of MKs undergoing proplatelet formation revealed a subset of proteins decreased in proplatelet-producing megakaryocytes, consistent with data showing that protein degradation is necessary for proplatelet formation. Specifically, the centrosome stabilizing proteins Aurora kinase (Aurk) A/B, Tpx2, Cdk1, and Plk1 were decreased in proplatelet-producing MKs. Furthermore, inhibition of AurkA and Plk1, but not Cdk1, significantly inhibited proplatelet formation in vitro over 83%. Conclusions: We hypothesize that proplatelet formation is triggered by centrosome destabilization and disassembly, and that the ubiquitin-proteasome pathway plays a crucial role in this transformation. Specifically, regulation of the AurkA/Plk1/Tpx2 pathway may be key in centrosome integrity and initiation of proplatelet formation. Determination of the mechanism by which the ubiquitin-proteasome pathway regulates the centrosome and facilitates proplatelet formation will allow us to design better strategies to target and reverse thrombocytopenia.


Sign in / Sign up

Export Citation Format

Share Document