Mountain ginseng inhibits skeletal muscle atrophy by decreasing muscle RING ﬁnger protein-1 and atrogin1 through forkhead box O3 in L6 myotubes

A good quality of life requires maintaining adequate skeletal muscle mass and strength, but therapeutic agents are lacking for this. We developed a bioassay-guided fractionation approach to identify molecules with hypertrophy-promoting effect in human skeletal muscle cells. We found that extracts from rosemary leaves induce muscle cell hypertrophy. By bioassay-guided purification we identified the phenolic diterpene carnosol as the compound responsible for the hypertrophy-promoting activity of rosemary leaf extracts. We then evaluated the impact of carnosol on the different signaling pathways involved in the control of muscle cell size. We found that activation of the NRF2 signaling pathway by carnosol is not sufficient to mediate its hypertrophy-promoting effect. Moreover, carnosol inhibits the expression of the ubiquitin ligase E3 Muscle RING Finger protein-1 that plays an important role in muscle remodeling, but has no effect on the protein synthesis pathway controlled by the protein kinase B/mechanistic target of rapamycin pathway. By measuring the chymotrypsin-like activity of the proteasome, we found that proteasome activity was significantly decreased by carnosol and Muscle RING Finger 1 inactivation. These results strongly suggest that carnosol can induce skeletal muscle hypertrophy by repressing the ubiquitin-proteasome system-dependent protein degradation pathway through inhibition of the E3 ubiquitin ligase Muscle RING Finger protein-1.

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Identification and characterization of Fbxl22, a novel skeletal muscle atrophy-promoting E3 ubiquitin ligase

AJP Cell Physiology ◽

10.1152/ajpcell.00253.2020 ◽

2020 ◽

Vol 319 (4) ◽

pp. C700-C719 ◽

Cited By ~ 1

Author(s):

David C. Hughes ◽

Leslie M. Baehr ◽

Julia R. Driscoll ◽

Sarah A. Lynch ◽

David S. Waddell ◽

...

Keyword(s):

Skeletal Muscle ◽

Muscle Atrophy ◽

Splice Variant ◽

Splice Variants ◽

Ring Finger ◽

Ubiquitin Ligases ◽

Skeletal Muscle Atrophy ◽

E3 Ubiquitin Ligases ◽

Muscle Mass Loss

Muscle-specific E3 ubiquitin ligases have been identified in muscle atrophy-inducing conditions. The purpose of the current study was to explore the functional role of F-box and leucine-rich protein 22 (Fbxl22), and a newly identified splice variant (Fbxl22–193), in skeletal muscle homeostasis and neurogenic muscle atrophy. In mouse C2C12 muscle cells, promoter fragments of the Fbxl22 gene were cloned and fused with the secreted alkaline phosphatase reporter gene to assess the transcriptional regulation of Fbxl22. The tibialis anterior muscles of male C57/BL6 mice (12–16 wk old) were electroporated with expression plasmids containing the cDNA of two Fbxl22 splice variants and tissues collected after 7, 14, and 28 days. Gastrocnemius muscles of wild-type and muscle-specific RING finger 1 knockout (MuRF1 KO) mice were electroporated with an Fbxl22 RNAi or empty plasmid and denervated 3 days posttransfection, and tissues were collected 7 days postdenervation. The full-length gene and novel splice variant are transcriptionally induced early (after 3 days) during neurogenic muscle atrophy. In vivo overexpression of Fbxl22 isoforms in mouse skeletal muscle leads to evidence of myopathy/atrophy, suggesting that both are involved in the process of neurogenic muscle atrophy. Knockdown of Fbxl22 in the muscles of MuRF1 KO mice resulted in significant additive muscle sparing 7 days after denervation. Targeting two E3 ubiquitin ligases appears to have a strong additive effect on protecting muscle mass loss with denervation, and these findings have important implications in the development of therapeutic strategies to treat muscle atrophy.

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miR-23a is decreased during muscle atrophy by a mechanism that includes calcineurin signaling and exosome-mediated export

AJP Cell Physiology ◽

10.1152/ajpcell.00266.2013 ◽

2014 ◽

Vol 306 (6) ◽

pp. C551-C558 ◽

Cited By ~ 74

Author(s):

Matthew B. Hudson ◽

Myra E. Woodworth-Hobbs ◽

Bin Zheng ◽

Jill A. Rahnert ◽

Mitsi A. Blount ◽

...

Keyword(s):

Skeletal Muscle ◽

Muscle Atrophy ◽

Ring Finger ◽

Skeletal Muscle Atrophy ◽

C2c12 Myotubes ◽

Activated T Cells ◽

Streptozotocin Induced Diabetes ◽

The Media ◽

The Relationship ◽

Deficient Mice

Skeletal muscle atrophy is prevalent in chronic diseases, and microRNAs (miRs) may play a key role in the wasting process. miR-23a was previously shown to inhibit the expression of atrogin-1 and muscle RING-finger protein-1 (MuRF1) in muscle. It also was reported to be regulated by cytoplasmic nuclear factor of activated T cells 3 (NFATc3) in cardiomyocytes. The objective of this study was to determine if miR-23a is regulated during muscle atrophy and to evaluate the relationship between calcineurin (Cn)/NFAT signaling and miR-23a expression in skeletal muscle cells during atrophy. miR-23a was decreased in the gastrocnemius of rats with acute streptozotocin-induced diabetes, a condition known to increase atrogin-1 and MuRF1 expression and cause atrophy. Treatment of C2C12 myotubes with dexamethasone (Dex) for 48 h also reduced miR-23a as well as RCAN1.4 mRNA, which is transcriptionally regulated by NFAT. NFATc3 nuclear localization and the amount of miR-23a decreased rapidly within 1 h of Dex administration, suggesting a link between Cn signaling and miR-23a. The level of miR-23a was lower in primary myotubes from mice lacking the α- or β-isoform of the CnA catalytic subunit than wild-type mice. Dex did not further suppress miR-23a in myotubes from Cn-deficient mice. Overexpression of CnAβ in C2C12 myotubes prevented Dex-induced suppression of miR-23a. Finally, miR-23a was present in exosomes isolated from the media of C2C12 myotubes, and Dex increased its exosomal abundance. Dex did not alter the number of exosomes released into the media. We conclude that atrophy-inducing conditions downregulate miR-23a in muscle by mechanisms involving attenuated Cn/NFAT signaling and selective packaging into exosomes.

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Ring finger protein 31–mediated atypical ubiquitination stabilizes forkhead box P3 and thereby stimulates regulatory T-cell function

Journal of Biological Chemistry ◽

10.1074/jbc.ra118.005802 ◽

2018 ◽

Vol 293 (52) ◽

pp. 20099-20111 ◽

Cited By ~ 11

Author(s):

Fuxiang Zhu ◽

Gang Yi ◽

Xu Liu ◽

Fangming Zhu ◽

Anna Zhao ◽

...

Keyword(s):

T Cell ◽

Regulatory T Cell ◽

Cell Function ◽

Ring Finger ◽

Ring Finger Protein ◽

Forkhead Box P3 ◽

Forkhead Box ◽

Finger Protein ◽

T Cell Function

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Forkhead box O3 plays a role in skeletal muscle atrophy through expression of E3 ubiquitin ligases MuRF-1 and atrogin-1 in Cushing’s syndrome

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00389.2016 ◽

2017 ◽

Vol 312 (6) ◽

pp. E495-E507 ◽

Cited By ~ 15

Author(s):

Seol-Hee Kang ◽

Hae-Ahm Lee ◽

Mina Kim ◽

Eunjo Lee ◽

Uy Dong Sohn ◽

...

Keyword(s):

Skeletal Muscle ◽

Muscle Atrophy ◽

Cushing’S Syndrome ◽

Ubiquitin Ligases ◽

Cushing's Syndrome ◽

Skeletal Muscle Atrophy ◽

E3 Ubiquitin Ligases ◽

Sprague Dawley ◽

Muscle Weight ◽

Forkhead Box

Cushing’s syndrome is caused by overproduction of the adrenocorticotropic hormone (ACTH), which stimulates the adrenal grand to make cortisol. Skeletal muscle wasting occurs in pathophysiological response to Cushing’s syndrome. The forkhead box (FOX) protein family has been implicated as a key regulator of muscle loss under conditions such as diabetes and sepsis. However, the mechanistic role of the FOXO family in ACTH-induced muscle atrophy is not understood. We hypothesized that FOXO3a plays a role in muscle atrophy through expression of the E3 ubiquitin ligases, muscle RING finger protein-1 (MuRF-1), and atrogin-1 in Cushing’s syndrome. For establishment of a Cushing’s syndrome animal model, Sprague-Dawley rats were implanted with osmotic minipumps containing ACTH (40 ng·kg−1·day−1). ACTH infusion significantly reduced muscle weight. In ACTH-infused rats, MuRF-1, atrogin-1, and FOXO3a were upregulated and the FOXO3a promoter was targeted by the glucocorticoid receptor (GR). Transcriptional activity and expression of FOXO3a were significantly decreased by the GR antagonist RU486. Treatment with RU486 reduced MuRF-1 and atrogin-1 expression in accordance with reduced enrichment of FOXO3a and Pol II on the promoters. Knockdown of FOXO3a prevented dexamethasone-induced MuRF-1 and atrogin-1 expression. These results indicate that FOXO3a plays a role in muscle atrophy through expression of MuRF-1 and atrogin-1 in Cushing’s syndrome.

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Hydrogen sulphide ameliorating skeletal muscle atrophy in db/db mice via Muscle RING finger 1 S‐sulfhydration

Journal of Cellular and Molecular Medicine ◽

10.1111/jcmm.15587 ◽

2020 ◽

Vol 24 (16) ◽

pp. 9362-9377 ◽

Cited By ~ 1

Author(s):

Fangping Lu ◽

Baoling Lu ◽

Linxue Zhang ◽

JingChen Wen ◽

Mengyi Wang ◽

...

Keyword(s):

Skeletal Muscle ◽

Muscle Atrophy ◽

Hydrogen Sulphide ◽

Ring Finger ◽

Skeletal Muscle Atrophy

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Trimetazidine Attenuates Dexamethasone-Induced Muscle Atrophy via Inhibiting NLRP3/GSDMD Pathway-Mediated Pyroptosis

10.20944/preprints202012.0643.v1 ◽

2020 ◽

Author(s):

Li Wang ◽

Ming-Qing He ◽

Xi-Yu Shen ◽

Kang-Zhen Zhang ◽

Can Zhao ◽

...

Keyword(s):

Skeletal Muscle ◽

Muscle Atrophy ◽

Ring Finger ◽

Muscle Performance ◽

Skeletal Muscle Atrophy ◽

C2c12 Myotubes ◽

High Dose ◽

Therapeutic Compound

Skeletal muscle atrophy is one of the major side effects of high dose or sustained usage of glucocorticoids. Pyroptosis is a novel form of pro-inflammatory programmed cell death that may contribute to skeletal muscle injury. Trimetazidine, a well-known anti-anginal agent, can also improve skeletal muscle performance both in human and mice. We here showed that dexamethasone induced atrophy, evidenced by the increase of muscle atrophy F-box (Atrogin-1) and muscle ring finger 1 (MuRF1) expression , and the decrease of myotube diameter in C2C12 myotubes. Dexamethasone also induced pyroptosis, indicated by upregulated pyroptosis-related protein NLRP3, Caspase-1 and GSDMD. Knockdown of NLRP3 or GSDMD attenuated dexamethasone-induced myotube pyroptosis and atrophy. Trimetazidine administration ameliorated dexamethasone-induced muscle atrophy both in vivo and in vitro. Moreover, trimetazidine improved exercise tolerance, as evidenced by increased running distance and running time, as well as increased skeletal muscle mass in dexamethasone-treated mice. Mechanically, trimetazidine could reverse dexamethasone-induced activation of pyroptosis both in C2C12 myotubes and in mice. Taken together, our present study demonstrated that NLRP3/GSDMD pathway-mediated pyroptosis was involved in dexamethasone-induced skeletal muscle atrophy. Trimetazidine could partially alleviate dexamethasone-induced skeletal muscle atrophy, and increase the diameter of C2C12 myotubes via inhibiting pyroptosis. Thus, trimetazidine might be a potential therapeutic compound for the prevention of muscle atrophy in glucocorticoid-treated patients.

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