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

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.

Download Full-text

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.

Download Full-text

Inhibition of Xanthine Oxidase by Allopurinol Prevents Skeletal Muscle Atrophy: Role of p38 MAPKinase and E3 Ubiquitin Ligases

PLoS ONE ◽

10.1371/journal.pone.0046668 ◽

2012 ◽

Vol 7 (10) ◽

pp. e46668 ◽

Cited By ~ 67

Author(s):

Frederic Derbre ◽

Beatriz Ferrando ◽

Mari Carmen Gomez-Cabrera ◽

Fabian Sanchis-Gomar ◽

Vladimir E. Martinez-Bello ◽

...

Keyword(s):

Skeletal Muscle ◽

Xanthine Oxidase ◽

Muscle Atrophy ◽

Ubiquitin Ligases ◽

Skeletal Muscle Atrophy ◽

E3 Ubiquitin Ligases

Download Full-text

Redox regulation of E3 ubiquitin ligases and their role in skeletal muscle atrophy

Free Radical Biology and Medicine ◽

10.1016/j.freeradbiomed.2014.10.799 ◽

2014 ◽

Vol 75 ◽

pp. S43-S44 ◽

Cited By ~ 2

Author(s):

Gloria Olaso-Gonzalez ◽

Beatriz Ferrando ◽

Frederic Derbre ◽

Andrea Salvador-Pascual ◽

Helena Cabo ◽

...

Keyword(s):

Skeletal Muscle ◽

Muscle Atrophy ◽

Redox Regulation ◽

Ubiquitin Ligases ◽

Skeletal Muscle Atrophy ◽

E3 Ubiquitin Ligases

Download Full-text

Matrine improves skeletal muscle atrophy by inhibiting E3 ubiquitin ligases and activating the Akt/mTOR/FoxO3α signaling pathway in C2C12 myotubes and mice

Oncology Reports ◽

10.3892/or.2019.7205 ◽

2019 ◽

Cited By ~ 4

Author(s):

Li Chen ◽

Linlin Chen ◽

Lili Wan ◽

Yan Huo ◽

Jinlu Huang ◽

...

Keyword(s):

Skeletal Muscle ◽

Signaling Pathway ◽

Muscle Atrophy ◽

Ubiquitin Ligases ◽

Skeletal Muscle Atrophy ◽

C2c12 Myotubes ◽

E3 Ubiquitin Ligases

Download Full-text

Skeletal muscle atrophy and the E3 ubiquitin ligases MuRF1 and MAFbx/atrogin-1

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00204.2014 ◽

2014 ◽

Vol 307 (6) ◽

pp. E469-E484 ◽

Cited By ~ 355

Author(s):

Sue C. Bodine ◽

Leslie M. Baehr

Keyword(s):

Skeletal Muscle ◽

Muscle Atrophy ◽

Striated Muscle ◽

Expression Patterns ◽

Ring Finger ◽

Physiological Role ◽

Ubiquitin Ligases ◽

Skeletal Muscle Atrophy ◽

E3 Ubiquitin Ligases ◽

Cellular Functions

Muscle RING finger 1 (MuRF1) and muscle atrophy F-box (MAFbx)/atrogin-1 were identified more than 10 years ago as two muscle-specific E3 ubiquitin ligases that are increased transcriptionally in skeletal muscle under atrophy-inducing conditions, making them excellent markers of muscle atrophy. In the past 10 years much has been published about MuRF1 and MAFbx with respect to their mRNA expression patterns under atrophy-inducing conditions, their transcriptional regulation, and their putative substrates. However, much remains to be learned about the physiological role of both genes in the regulation of mass and other cellular functions in striated muscle. Although both MuRF1 and MAFbx are enriched in skeletal, cardiac, and smooth muscle, this review will focus on the current understanding of MuRF1 and MAFbx in skeletal muscle, highlighting the critical questions that remain to be answered.

Download Full-text

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

10.1101/2020.04.24.059659 ◽

2020 ◽

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 ◽

Ubiquitin Ligases ◽

Skeletal Muscle Atrophy ◽

E3 Ubiquitin Ligases ◽

Muscle Mass Loss ◽

Muscle Homeostasis

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 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 weeks 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 MuRF1 knockout mice were electroporated with an Fbxl22 RNAi or empty plasmid, denervated three days post-transfection, and tissues collected 7 days post-denervation. 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 lead to evidence of myopathy/atrophy suggesting that both are involved in the process of neurogenic muscle atrophy. Knockdown of Fbxl22 in MuRF1 KO muscles resulted in significant additive muscle sparing at 7 days of 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.

Download Full-text

Paradoxical effect of IKKβ inhibition on the expression of E3 ubiquitin ligases and unloading-induced skeletal muscle atrophy

Physiological Reports ◽

10.14814/phy2.13291 ◽

2017 ◽

Vol 5 (16) ◽

pp. e13291 ◽

Cited By ~ 10

Author(s):

Svetlana P. Belova ◽

Boris S. Shenkman ◽

Tatiana Y. Kostrominova ◽

Tatiana L. Nemirovskaya

Keyword(s):

Skeletal Muscle ◽

Muscle Atrophy ◽

Ubiquitin Ligases ◽

Skeletal Muscle Atrophy ◽

Paradoxical Effect ◽

E3 Ubiquitin Ligases

Download Full-text

AMP-activated protein kinase agonists increase mRNA content of the muscle-specific ubiquitin ligases MAFbx and MuRF1 in C2C12 cells

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00622.2006 ◽

2007 ◽

Vol 292 (6) ◽

pp. E1555-E1567 ◽

Cited By ~ 93

Author(s):

Brian J. Krawiec ◽

Gerald J. Nystrom ◽

Robert A. Frost ◽

Leonard S. Jefferson ◽

Charles H. Lang

Keyword(s):

Skeletal Muscle ◽

Protein Kinase ◽

Mrna Expression ◽

Muscle Atrophy ◽

Ubiquitin Ligases ◽

C2c12 Cells ◽

Skeletal Muscle Atrophy ◽

Compound C ◽

Mrna Content ◽

Amp Activated Protein Kinase

The hypothesis of the present study was that exposure of differentiated muscle cells to agonists of the AMP-activated protein kinase (AMPK) would increase the mRNA content of the muscle-specific ubiquitin ligases muscle atrophy F-box (MAFbx) and muscle RING finger 1 (MuRF1). C2C12 cells were incubated with incremental doses of 5-aminoimidazol-4-carboximide ribonucleoside (AICAR) or metformin for 24 h. Both MAFbx and MuRF1 mRNA increased dose dependently in response to these AMPK activators. AICAR, metformin, and 2-deoxy-d-glucose produced time-dependent alterations in ubiquitin ligase expression, typified by a biphasic pattern of expression marked by an acute repression followed by a sustained induction. AMPK-activating treatments in conjunction with dexamethasone produced a pronounced synergistic effect on ligase mRNA expression at later time points. This cooperative response occurred in the absence of a dexamethasone-dependent increase in AMPK expression or activity, as determined by immunoblotting for phosphorylation and expression of AMPKα and its downstream target acetyl-CoA carboxylase (ACC). These responses elicited by AMPK activation singly or in combination with dexamethasone did not extend to the mRNA expression of the UBR box family E3s UBR1/E3αI and UBR2/E3αII. Treatment with the AMPK inhibitor compound C prevented increases in MAFbx and MuRF1 mRNA in response to serum deprivation, as well as AICAR and dexamethasone treatment individually or jointly. Stimulation of AMPK activity in vivo via AICAR injection increased both MAFbx and MuRF1 mRNA in murine skeletal muscle. These data suggest that activation of AMPK in skeletal muscle results in a specific upregulation of MAFbx and MuRF1, responses that are reminiscent of the proposed atrophic transcriptional program executed under various conditions of skeletal muscle wasting. Therefore, AMPK may be a critical component of the intercalated network of signaling pathways governing skeletal muscle atrophy, where its input acts to modify anti- and proatrophic signals to influence gene expression in reaction to catabolic perturbations.

Download Full-text