Supplementation of ketoacids contributes to the up-regulation of the Wnt7a/Akt/p70S6K pathway and the down-regulation of apoptotic and ubiquitin–proteasome systems in the muscle of 5/6 nephrectomised rats

Ketoacids (KA) are known to improve muscle mass among patients with chronic kidney disease (CKD) on a low-protein diet (CKD-LPD), but the mechanism of its preventive effects on muscle atrophy still remains unclear. Since muscle atrophy in CKD may be attributable to the down-regulation of the Wnt7a/Akt/p70S6K pathway and the activation of the ubiquitin–proteasome system (UPS) and the apoptotic signalling pathway, a hypothesis can readily be drawn that KA supplementation improves muscle mass by up-regulating the Wnt7a/Akt/p70S6K pathway and counteracting the activation of the UPS and caspase-3-dependent apoptosis in the muscle of CKD-LPD rats. Rats with 5/6 nephrectomy were randomly divided into three groups, and fed with either 22 % protein (normal-protein diet; NPD), 6 % protein (LPD) or 5 % protein plus 1 % KA for 24 weeks. Sham-operated rats with NPD intake were used as the control. The results demonstrated that KA supplementation improved protein synthesis and increased related mediators such as Wnt7a, phosphorylated Akt and p70S6K in the muscle of CKD-LPD rats. It also inhibited protein degradation, withheld the increase in ubiquitin and its ligases MAFbx (muscle atrophy F-box) and MuRF1 (muscle ring finger-1) as well as attenuated proteasome activity in the muscle of CKD-LPD rats. Moreover, KA supplementation gave rise to a reduction in DNA fragment, cleaved caspase-3 and 14 kDa actin fragment via the down-regulation of the Bax:Bcl-2 ratio in the muscle of CKD-LPD rats. The beneficial effects unveiled herein further consolidate that KA may be a better therapeutic strategy for muscle atrophy in CKD-LPD.

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Increasing autophagy does not affect neurogenic muscle atrophy

European Journal of Translational Myology ◽

10.4081/ejtm.2018.7687 ◽

2018 ◽

Vol 28 (3) ◽

Cited By ~ 5

Author(s):

Eva Pigna ◽

Krizia Sanna ◽

Dario Coletti ◽

Zhenlin Li ◽

Ara Parlakian ◽

...

Keyword(s):

Muscle Mass ◽

Muscle Atrophy ◽

Ubiquitin Proteasome System ◽

Autophagic Flux ◽

Molecular Pathways ◽

Muscle Loss ◽

Relative Contribution ◽

Ubiquitin Proteasome ◽

Muscle Mass Loss ◽

Kinetics Of

Physiological autophagy plays a crucial role in the regulation of muscle mass and metabolism, while the excessive induction or the inhibition of the autophagic flux contributes to the progression of several diseases. Autophagy can be activated by different stimuli, including cancer, exercise, caloric restriction and denervation. The latter leads to muscle atrophy through the activation of catabolic pathways, i.e. the ubiquitin-proteasome system and autophagy. However, the kinetics of autophagy activation and the upstream molecular pathways in denervated skeletal muscle have not been reported yet. In this study, we characterized the kinetics of autophagic induction, quickly triggered by denervation, and report the Akt/mTOR axis activation. Besides, with the aim to assess the relative contribution of autophagy in neurogenic muscle atrophy, we triggered autophagy with different stimuli along with denervation, and observed that four week-long autophagic induction, by either intermitted fasting or rapamycin treatment, did not significantly affect muscle mass loss. We conclude that: i) autophagy does not play a major role in inducing muscle loss following denervation; ii) nonetheless, autophagy may have a regulatory role in denervation induced muscle atrophy, since it is significantly upregulated as early as eight hours after denervation; iii) Akt/mTOR axis, AMPK and FoxO3a are activated consistently with the progression of muscle atrophy, further highlighting the complexity of the signaling response to the atrophying stimulus deriving from denervation.

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Calpain and caspase-3 play required roles in immobilization-induced limb muscle atrophy

Journal of Applied Physiology ◽

10.1152/japplphysiol.00925.2012 ◽

2013 ◽

Vol 114 (10) ◽

pp. 1482-1489 ◽

Cited By ~ 50

Author(s):

Erin E. Talbert ◽

Ashley J. Smuder ◽

Kisuk Min ◽

Oh Sung Kwon ◽

Scott K. Powers

Keyword(s):

Muscle Atrophy ◽

Caspase 3 ◽

Respiratory Muscles ◽

Ubiquitin Proteasome System ◽

Type I ◽

Disuse Atrophy ◽

Limb Muscle ◽

Disuse Muscle Atrophy ◽

Ubiquitin Proteasome ◽

Rat Soleus Muscle

Prolonged skeletal muscle inactivity results in a rapid decrease in fiber size, primarily due to accelerated proteolysis. Although several proteases are known to contribute to disuse muscle atrophy, the ubiquitin proteasome system is often considered the most important proteolytic system during many conditions that promote muscle wasting. Emerging evidence suggests that calpain and caspase-3 may also play key roles in inactivity-induced atrophy of respiratory muscles, but it remains unknown if these proteases are essential for disuse atrophy in limb skeletal muscles. Therefore, we tested the hypothesis that activation of both calpain and caspase-3 is required for locomotor muscle atrophy induced by hindlimb immobilization. Seven days of immobilization (i.e., limb casting) promoted significant atrophy in type I muscle fibers of the rat soleus muscle. Independent pharmacological inhibition of calpain or caspase-3 prevented this casting-induced atrophy. Interestingly, inhibition of calpain activity also prevented caspase-3 activation, and, conversely, inhibition of caspase-3 prevented calpain activation. These findings indicate that a regulatory cross talk exists between these proteases and provide the first evidence that the activation of calpain and caspase-3 is required for inactivity-induced limb muscle atrophy.

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Inhibition of Stat3 Activation Suppresses Caspase-3 and the Ubiquitin-Proteasome System, Leading to Preservation of Muscle Mass in Cancer Cachexia

Journal of Biological Chemistry ◽

10.1074/jbc.m115.641514 ◽

2015 ◽

Vol 290 (17) ◽

pp. 11177-11187 ◽

Cited By ~ 78

Author(s):

Kleiton Augusto Santos Silva ◽

Jiangling Dong ◽

Yanjun Dong ◽

Yanlan Dong ◽

Nestor Schor ◽

...

Keyword(s):

Muscle Mass ◽

Cancer Cachexia ◽

Caspase 3 ◽

Ubiquitin Proteasome System ◽

Ubiquitin Proteasome

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Involvement of AMPK in regulating slow-twitch muscle atrophy during hindlimb unloading in mice

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00165.2015 ◽

2015 ◽

Vol 309 (7) ◽

pp. E651-E662 ◽

Cited By ~ 31

Author(s):

Tatsuro Egawa ◽

Ayumi Goto ◽

Yoshitaka Ohno ◽

Shingo Yokoyama ◽

Akihiro Ikuta ◽

...

Keyword(s):

Skeletal Muscle ◽

Protein Degradation ◽

Muscle Mass ◽

Muscle Atrophy ◽

Skeletal Muscle Mass ◽

Ubiquitin Proteasome System ◽

Hindlimb Unloading ◽

Slow Twitch Muscle ◽

Ubiquitin Proteasome ◽

Slow Twitch

AMPK is considered to have a role in regulating skeletal muscle mass. However, there are no studies investigating the function of AMPK in modulating skeletal muscle mass during atrophic conditions. In the present study, we investigated the difference in unloading-associated muscle atrophy and molecular functions in response to 2-wk hindlimb suspension between transgenic mice overexpressing the dominant-negative mutant of AMPK (AMPK-DN) and their wild-type (WT) littermates. Male WT ( n = 24) and AMPK-DN ( n = 24) mice were randomly divided into two groups: an untreated preexperimental control group ( n = 12 in each group) and an unloading ( n = 12 in each group) group. The relative soleus muscle weight and fiber cross-sectional area to body weight were decreased by ∼30% in WT mice by hindlimb unloading and by ∼20% in AMPK-DN mice. There were no changes in puromycin-labeled protein or Akt/70-kDa ribosomal S6 kinase signaling, the indicators of protein synthesis. The expressions of ubiquitinated proteins and muscle RING finger 1 mRNA and protein, markers of the ubiquitin-proteasome system, were increased by hindlimb unloading in WT mice but not in AMPK-DN mice. The expressions of molecules related to the protein degradation system, phosphorylated forkhead box class O3a, inhibitor of κBα, microRNA (miR)-1, and miR-23a, were decreased only in WT mice in response to hindlimb unloading, and 72-kDa heat shock protein expression was higher in AMPK-DN mice than in WT mice. These results imply that AMPK partially regulates unloading-induced atrophy of slow-twitch muscle possibly through modulation of the protein degradation system, especially the ubiquitin-proteasome system.

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Myofibril breakdown during atrophy is a delayed response requiring the transcription factor PAX4 and desmin depolymerization

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1612988114 ◽

2017 ◽

Vol 114 (8) ◽

pp. E1375-E1384 ◽

Cited By ~ 23

Author(s):

Alexandra Volodin ◽

Idit Kosti ◽

Alfred Lewis Goldberg ◽

Shenhav Cohen

Keyword(s):

Transcription Factor ◽

Muscle Atrophy ◽

Ubiquitin Proteasome System ◽

Delayed Response ◽

Myofibrillar Proteins ◽

Down Regulation ◽

Two Phase ◽

Gene Encoding ◽

Thin Filaments ◽

Ubiquitin Proteasome

A hallmark of muscle atrophy is the excessive degradation of myofibrillar proteins primarily by the ubiquitin proteasome system. In mice, during the rapid muscle atrophy induced by fasting, the desmin cytoskeleton and the attached Z-band–bound thin filaments are degraded after ubiquitination by the ubiquitin ligase tripartite motif-containing protein 32 (Trim32). To study the order of events leading to myofibril destruction, we investigated the slower atrophy induced by denervation (disuse). We show that myofibril breakdown is a two-phase process involving the initial disassembly of desmin filaments by Trim32, which leads to the later myofibril breakdown by enzymes, whose expression is increased by the paired box 4 (PAX4) transcription factor. After denervation of mouse tibialis anterior muscles, phosphorylation and Trim32-dependent ubiquitination of desmin filaments increased rapidly and stimulated their gradual depolymerization (unlike their rapid degradation during fasting). Trim32 down-regulation attenuated the loss of desmin and myofibrillar proteins and reduced atrophy. Although myofibrils and desmin filaments were intact at 7 d after denervation, inducing the dissociation of desmin filaments caused an accumulation of ubiquitinated proteins and rapid destruction of myofibrils. The myofibril breakdown normally observed at 14 d after denervation required not only dissociation of desmin filaments, but also gene induction by PAX4. Down-regulation of PAX4 or its target gene encoding the p97/VCP ATPase reduced myofibril disassembly and degradation on denervation or fasting. Thus, during atrophy, the initial loss of desmin is critical for the subsequent myofibril destruction, and over time, myofibrillar proteins become more susceptible to PAX4-induced enzymes that promote proteolysis.

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Identification of the MuRF1 skeletal muscle ubiquitylome through quantitative proteomics

Function ◽

10.1093/function/zqab029 ◽

2021 ◽

Author(s):

Leslie M Baehr ◽

David C Hughes ◽

Sarah A Lynch ◽

Delphi Van Haver ◽

Teresa Mendes Maia ◽

...

Keyword(s):

Skeletal Muscle ◽

Muscle Atrophy ◽

Potential Role ◽

Ubiquitin Proteasome System ◽

In Vivo Electroporation ◽

Adult Mice ◽

Expression Of Genes ◽

Regulation Of Metabolism ◽

Ubiquitin Proteasome

Abstract MuRF1 (TRIM63) is a muscle-specific E3 ubiquitin ligase and component of the ubiquitin proteasome system. MuRF1 is transcriptionally upregulated under conditions that cause muscle loss, in both rodents and humans, and is a recognized marker of muscle atrophy. In this study, we used in vivo electroporation to determine if MuRF1 overexpression alone can cause muscle atrophy and, in combination with ubiquitin proteomics, identify the endogenous MuRF1 substrates in skeletal muscle. Overexpression of MuRF1 in adult mice increases ubiquitination of myofibrillar and sarcoplasmic proteins, increases expression of genes associated with neuromuscular junction instability, and causes muscle atrophy. A total of 169 ubiquitination sites on 56 proteins were found to be regulated by MuRF1. MuRF1-mediated ubiquitination targeted both thick and thin filament contractile proteins, as well as, glycolytic enzymes, deubiquitinases, p62, and VCP. These data reveal a potential role for MuRF1 in not only the breakdown of the sarcomere, but also the regulation of metabolism and other proteolytic pathways in skeletal muscle.

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Activation of the ubiquitin-proteasome system contributes to oculopharyngeal muscular dystrophy through muscle atrophy

PLoS Genetics ◽

10.1371/journal.pgen.1010015 ◽

2022 ◽

Vol 18 (1) ◽

pp. e1010015

Author(s):

Cécile Ribot ◽

Cédric Soler ◽

Aymeric Chartier ◽

Sandy Al Hayek ◽

Rima Naït-Saïdi ◽

...

Keyword(s):

Muscular Dystrophy ◽

Muscle Atrophy ◽

Late Onset ◽

Oral Treatment ◽

Ubiquitin Proteasome System ◽

Proteasome Activity ◽

Functional Study ◽

Oculopharyngeal Muscular Dystrophy ◽

Ubiquitin Proteasome ◽

And Function

Oculopharyngeal muscular dystrophy (OPMD) is a late-onset disorder characterized by progressive weakness and degeneration of specific muscles. OPMD is due to extension of a polyalanine tract in poly(A) binding protein nuclear 1 (PABPN1). Aggregation of the mutant protein in muscle nuclei is a hallmark of the disease. Previous transcriptomic analyses revealed the consistent deregulation of the ubiquitin-proteasome system (UPS) in OPMD animal models and patients, suggesting a role of this deregulation in OPMD pathogenesis. Subsequent studies proposed that UPS contribution to OPMD involved PABPN1 aggregation. Here, we use a Drosophila model of OPMD to address the functional importance of UPS deregulation in OPMD. Through genome-wide and targeted genetic screens we identify a large number of UPS components that are involved in OPMD. Half dosage of UPS genes reduces OPMD muscle defects suggesting a pathological increase of UPS activity in the disease. Quantification of proteasome activity confirms stronger activity in OPMD muscles, associated with degradation of myofibrillar proteins. Importantly, improvement of muscle structure and function in the presence of UPS mutants does not correlate with the levels of PABPN1 aggregation, but is linked to decreased degradation of muscle proteins. Oral treatment with the proteasome inhibitor MG132 is beneficial to the OPMD Drosophila model, improving muscle function although PABPN1 aggregation is enhanced. This functional study reveals the importance of increased UPS activity that underlies muscle atrophy in OPMD. It also provides a proof-of-concept that inhibitors of proteasome activity might be an attractive pharmacological approach for OPMD.

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Pueraria lobata and Daidzein Reduce Cytotoxicity by Enhancing Ubiquitin-Proteasome System Function in SCA3-iPSC-Derived Neurons

Oxidative Medicine and Cellular Longevity ◽

10.1155/2019/8130481 ◽

2019 ◽

Vol 2019 ◽

pp. 1-18

Author(s):

I-Cheng Chen ◽

Kuo-Hsuan Chang ◽

Yi-Jing Chen ◽

Yi-Chun Chen ◽

Guey-Jen Lee-Chen ◽

...

Keyword(s):

Proteasome Inhibitor ◽

Caspase 3 ◽

Neurodegenerative Disorder ◽

Ubiquitin Proteasome System ◽

Proteasome Activity ◽

Cag Repeats ◽

Spinocerebellar Ataxia Type ◽

Pueraria Lobata ◽

Protein Ubiquitination ◽

Ubiquitin Proteasome

Spinocerebellar ataxia type 3 (SCA3) is an autosomal dominant neurodegenerative disorder caused by a CAG repeat expansion within the ATXN3/MJD1 gene. The expanded CAG repeats encode a polyglutamine (polyQ) tract at the C-terminus of the ATXN3 protein. ATXN3 containing expanded polyQ forms aggregates, leading to subsequent cellular dysfunctions including an impaired ubiquitin-proteasome system (UPS). To investigate the pathogenesis of SCA3 and develop potential therapeutic strategies, we established induced pluripotent stem cell (iPSC) lines from SCA3 patients (SCA3-iPSC). Neurons derived from SCA3-iPSCs formed aggregates that are positive to the polyQ marker 1C2. Treatment with the proteasome inhibitor, MG132, on SCA3-iPSC-derived neurons downregulated proteasome activity, increased production of radical oxygen species (ROS), and upregulated the cleaved caspase 3 level and caspase 3 activity. This increased susceptibility to the proteasome inhibitor can be rescued by a Chinese herbal medicine (CHM) extract NH037 (from Pueraria lobata) and its constituent daidzein via upregulating proteasome activity and reducing protein ubiquitination, oxidative stress, cleaved caspase 3 level, and caspase 3 activity. Our results successfully recapitulate the key phenotypes of the neurons derived from SCA3 patients, as well as indicate the potential of NH037 and daidzein in the treatment for SCA3 patients.

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The ubiquitin proteasome system in atrophying skeletal muscle: roles and regulation

AJP Cell Physiology ◽

10.1152/ajpcell.00125.2016 ◽

2016 ◽

Vol 311 (3) ◽

pp. C392-C403 ◽

Cited By ~ 57

Author(s):

Philippe A. Bilodeau ◽

Erin S. Coyne ◽

Simon S. Wing

Keyword(s):

Signaling Pathways ◽

Muscle Atrophy ◽

Molecular Mechanisms ◽

Muscle Wasting ◽

Clinical Problem ◽

Ubiquitin Proteasome System ◽

Mechanisms Of Action ◽

Loss Of Function ◽

Critical Determinant ◽

Ubiquitin Proteasome

Muscle atrophy complicates many diseases as well as aging, and its presence predicts both decreased quality of life and survival. Much work has been conducted to define the molecular mechanisms involved in maintaining protein homeostasis in muscle. To date, the ubiquitin proteasome system (UPS) has been shown to play an important role in mediating muscle wasting. In this review, we have collated the enzymes in the UPS whose roles in muscle wasting have been confirmed through loss-of-function studies. We have integrated information on their mechanisms of action to create a model of how they work together to produce muscle atrophy. These enzymes are involved in promoting myofibrillar disassembly and degradation, activation of autophagy, inhibition of myogenesis as well as in modulating the signaling pathways that control these processes. Many anabolic and catabolic signaling pathways are involved in regulating these UPS genes, but none appear to coordinately regulate a large number of these genes. A number of catabolic signaling pathways appear to instead function by inhibition of the insulin/IGF-I/protein kinase B anabolic pathway. This pathway is a critical determinant of muscle mass, since it can suppress key ubiquitin ligases and autophagy, activate protein synthesis, and promote myogenesis through its downstream mediators such as forkhead box O, mammalian target of rapamycin, and GSK3β, respectively. Although much progress has been made, a more complete inventory of the UPS genes involved in mediating muscle atrophy, their mechanisms of action, and their regulation will be useful for identifying novel therapeutic approaches to this important clinical problem.

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Excessive glucocorticoid-induced muscle MuRF1 overexpression is independent of Akt/FoXO1 pathway

Bioscience Reports ◽

10.1042/bsr20171056 ◽

2017 ◽

Vol 37 (6) ◽

Cited By ~ 4

Author(s):

Xiao Juan Wang ◽

Jing Jing Xiao ◽

Lei Liu ◽

Hong Chao Jiao ◽

Hai Lin

Keyword(s):

Muscle Protein ◽

Mammalian Target Of Rapamycin ◽

Ring Finger ◽

Ubiquitin Proteasome System ◽

C2c12 Cells ◽

Detectable Effect ◽

High Concentration ◽

Mtor Phosphorylation ◽

Ubiquitin Proteasome

The ubiquitin-proteasome system (UPS)-dependent proteolysis plays a major role in the muscle catabolic action of glucocorticoids (GCs). Atrogin-1 and muscle-specific RING finger protein 1 (MuRF1), two E3 ubiquitin ligases, are uniquely expressed in muscle. It has been previously demonstrated that GC treatment induced MuRF1 and atrogin-1 overexpression. However, it is yet unclear whether the higher pharmacological dose of GCs induced muscle protein catabolism through MuRF1 and atrogin-1. In the present study, the role of atrogin-1 and MuRF1 in C2C12 cells protein metabolism during excessive dexamethasone (DEX) was studied. The involvement of Akt/forkhead box O1 (FoXO1) signaling pathway and the cross-talk between anabolic regulator mammalian target of rapamycin (mTOR) and catabolic regulator FoXO1 were investigated. High concentration of DEX increased MuRF1 protein level in a time-dependent fashion (P<0.05), while had no detectable effect on atrogin-1 protein (P>0.05). FoXO1/3a (Thr24/32) phosphorylation was enhanced (P<0.05), mTOR phosphorylation was suppressed (P<0.05), while Akt protein expression was not affected (P>0.05) by DEX. RU486 treatment inhibited the DEX-induced increase of FoXO1/3a phosphorylation (P<0.05) and MuRF1 protein; LY294002 (LY) did not restore the stimulative effect of DEX on the FoXO1/3a phosphorylation (P>0.05), but inhibited the activation of MuRF1 protein induced by DEX (P<0.05); rapamycin (RAPA) inhibited the stimulative effect of DEX on the FoXO1/3a phosphorylation and MuRF1 protein (P<0.05).

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