MBNL1-Associated Mitochondrial Dysfunction and Apoptosis in C2C12 Myotubes and Mouse Skeletal Muscle

We explored the interrelationship between a tissue-specific alternative splicing factor muscleblind-like 1 (MBNL1) and peroxisome proliferator-activated receptor-γ coactivator 1-α (PGC-1α), B-cell lymphoma 2 (Bcl-2) or Bcl-2-associated X protein (Bax) in C2C12 myotubes and mouse skeletal muscle to investigate a possible physiological role of MBNL1 in mitochondrial-associated apoptosis of skeletal muscle. Expression level of PGC-1α and mitochondrial membrane potential evaluated by the fluorescence ratio of JC-1 aggregate to monomer in C2C12 myotubes were suppressed by knockdown of MBNL1. Conversely, the ratio of Bax to Bcl-2 as well as the apoptotic index in C2C12 myotubes was increased by MBNL1 knockdown. In plantaris muscle, on the other hand, not only the minimum muscle fiber diameter but also the expression level of MBNL1 and PGC-1α in of 100-week-old mice were significantly lower than that of 10-week-old mice. Furthermore, the ratio of Bax to Bcl-2 in mouse plantaris muscle was increased by aging. These results suggest that MBNL1 may play a key role in aging-associated muscle atrophy accompanied with mitochondrial dysfunction and apoptosis via mediating PGC-1α expression in skeletal muscle.

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Analysis of the the silencing mediator of retinoid and thyroid receptors (SMRT/Ncor2)- and peroxisome proliferator activated receptor-γ coactivator 1- β (PGC1β/Ppargc1b)-regulated transcriptomes in mouse skeletal muscle

Signaling Pathways Project Datasets ◽

10.1621/kexa1iann4 ◽

2016 ◽

Author(s):

C Handschin

Keyword(s):

Skeletal Muscle ◽

Peroxisome Proliferator ◽

Peroxisome Proliferator Activated Receptor ◽

Mouse Skeletal Muscle

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Tissue-specific control of mitochondrial respiration in obesity-related insulin resistance and diabetes

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00159.2011 ◽

2012 ◽

Vol 302 (6) ◽

pp. E731-E739 ◽

Cited By ~ 81

Author(s):

Maria H. Holmström ◽

Eduardo Iglesias-Gutierrez ◽

Juleen R. Zierath ◽

Pablo M. Garcia-Roves

Keyword(s):

Insulin Resistance ◽

Skeletal Muscle ◽

Mitochondrial Dysfunction ◽

Mitochondrial Respiration ◽

Mitochondrial Dynamics ◽

Acid Oxidation ◽

Peroxisome Proliferator ◽

Respiratory Capacity ◽

Tissue Specific ◽

Mitochondrial Respiratory

The tissue-specific role of mitochondrial respiratory capacity in the development of insulin resistance and type 2 diabetes is unclear. We determined mitochondrial function in glycolytic and oxidative skeletal muscle and liver from lean (+/ ?) and obese diabetic ( db/db) mice. In lean mice, the mitochondrial respiration pattern differed between tissues. Tissue-specific mitochondrial profiles were then compared between lean and db/db mice. In liver, mitochondrial respiratory capacity and protein expression, including peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), was decreased in db/db mice, consistent with increased mitochondrial fission. In glycolytic muscle, mitochondrial respiration, as well as protein and mRNA expression of mitochondrial markers, was increased in db/db mice, suggesting increased mitochondrial content and fatty acid oxidation capacity. In oxidative muscle, mitochondrial complex I function and PGC-1α and mitochondrial transcription factor A (TFAM) protein levels were decreased in db/db mice, along with increased level of proteins related to mitochondrial dynamics. In conclusion, mitochondrial respiratory performance is under the control of tissue-specific mechanisms and is not uniformly altered in response to obesity. Furthermore, insulin resistance in glycolytic skeletal muscle can be maintained by a mechanism independent of mitochondrial dysfunction. Conversely, insulin resistance in liver and oxidative skeletal muscle from db/db mice is coincident with mitochondrial dysfunction.

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AICAR treatment for 14 days normalizes obesity-induced dysregulation of TORC1 signaling and translational capacity in fasted skeletal muscle

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00337.2010 ◽

2010 ◽

Vol 299 (6) ◽

pp. R1546-R1554 ◽

Cited By ~ 32

Author(s):

Joshua C. Drake ◽

Stephen E. Alway ◽

John M. Hollander ◽

David L. Williamson

Keyword(s):

Skeletal Muscle ◽

Muscle Mass ◽

Mrna Translation ◽

Mtor Signaling ◽

Initiation Factor ◽

Saline Control ◽

Obese Mouse ◽

Peroxisome Proliferator ◽

Eukaryotic Initiation Factor ◽

Mouse Skeletal Muscle

The aim of this study was to determine the effect of 14 days of 5-aminoimidazole-4-carboxamide-1β-4-ribofuranoside (AICAR) treatment on mammalian target of rapamycin (mTOR) signaling and mTOR-regulated processes (i.e., translation initiation) in obese mouse skeletal muscle. Our hypothesis was that daily treatment (14 days) with AICAR would normalize obesity-induced alterations in skeletal muscle mTOR signaling and mTOR-regulated processes to lean levels and positively affect muscle mass. Fourteen-week-old male, lean (L; 31.3 g body wt) wild-type and ob/ob (O; 59.6 g body wt) mice were injected with the AMP-activated kinase (AMPK) activator AICAR (A) at 0.5 mg·g body wt−1·day−1 or saline control (C) for 14 days. At 24 h after the last injection (including a 12-h fast), all mice were killed, and the plantar flexor complex muscle (gastrocnemius, soleus, and plantaris) was excised for analysis. Muscle mass was lower in OC (159 ± 12 mg) than LC, LA, and OA (176 ± 10, 178 ± 9, and 166 ± 16 mg, respectively) mice, independent of a body weight change. A decrease in obese muscle mass corresponded with higher muscle cross section staining intensity for lipid and glycogen, higher blood glucose and insulin levels, and lower nuclear-enriched fractions for peroxisome proliferator-activated receptor-γ coactivator-1α protein expression in OC skeletal muscle, which was normalized with AICAR treatment. AMPK and acetyl-cocarboxylase phosphorylation was reduced in OC mice and augmented by AICAR treatment in OA mice. Conversely, OC mice displayed higher activation of downstream targets (S6 kinase-1 and ribosomal protein S6) of mTOR and lower raptor-associated mTOR than LC mice, which were reciprocally altered after 14 days of AICAR treatment. Dysregulation of translational capacity was improved in OA mice, as assessed by sucrose density gradient fractionation of ribosomes, total and ribosome-associated RNA content, eukaryotic initiation factor 4F complex formation, and eukaryotic initiation factor 4G phosphorylation. These data show that short-term (14 days) AMPK agonist treatment augments regulatory processes in atrophic obese mouse skeletal muscle through the normalization of mTOR signaling and mRNA translation closer to lean levels.

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CLOCK and BMAL1 Regulate Muscle Insulin Sensitivity via SIRT1 in Male Mice

Endocrinology ◽

10.1210/en.2015-2027 ◽

2016 ◽

Vol 157 (6) ◽

pp. 2259-2269 ◽

Cited By ~ 33

Author(s):

Jun Liu ◽

Ben Zhou ◽

Menghong Yan ◽

Rui Huang ◽

Yuangao Wang ◽

...

Keyword(s):

Insulin Resistance ◽

Skeletal Muscle ◽

Insulin Sensitivity ◽

Molecular Mechanisms ◽

Ectopic Expression ◽

Sirtuin 1 ◽

C2c12 Myotubes ◽

Constant Darkness ◽

Circadian Misalignment ◽

Mouse Skeletal Muscle

Circadian misalignment induces insulin resistance in both human and animal models, and skeletal muscle is the largest organ response to insulin. However, how circadian clock regulates muscle insulin sensitivity and the underlying molecular mechanisms are still largely unknown. Here we show circadian locomotor output cycles kaput (CLOCK) and brain and muscle aryl hydrocarbon receptor nuclear translocator-like protein (BMAL)-1, two core circadian transcription factors, are down-regulated in insulin-resistant C2C12 myotubes and mouse skeletal muscle. Furthermore, insulin signaling is attenuated in the skeletal muscle of ClockΔ19/Δ19 mice, and knockdown of CLOCK or BMAL1 by small interfering RNAs induces insulin resistance in C2C12 myotubes. Consistently, ectopic expression of CLOCK and BMAL1 improves insulin sensitivity in C2C12 myotubes. Moreover, CLOCK and BMAL1 regulate the expression of sirtuin 1 (SIRT1), an important regulator of insulin sensitivity, in C2C12 myotubes and mouse skeletal muscle, and two E-box elements in Sirt1 promoter are responsible for its CLOCK- and BMAL1-dependent transcription in muscle cells. Further studies show that CLOCK and BMAL1 regulate muscle insulin sensitivity through SIRT1. In addition, we find that BMAL1 and SIRT1 are decreased in the muscle of mice maintained in constant darkness, and resveratrol supplementation activates SIRT1 and improves insulin sensitivity. All these data demonstrate that CLOCK and BMAL1 regulate muscle insulin sensitivity via SIRT1, and activation of SIRT1 might be a potential valuable strategy to attenuate muscle insulin resistance related to circadian misalignment.

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Breast cancer-associated skeletal muscle mitochondrial dysfunction and lipid accumulation is reversed by PPARG

AJP Cell Physiology ◽

10.1152/ajpcell.00264.2020 ◽

2021 ◽

Author(s):

Hannah E. Wilson ◽

David A. Stanton ◽

Stephanie Rellick ◽

Werner Geldenhuys ◽

Emidio E. Pistilli

Keyword(s):

Breast Cancer ◽

Skeletal Muscle ◽

Mitochondrial Dysfunction ◽

Mitochondrial Function ◽

Lipid Accumulation ◽

Transcriptional Activity ◽

Target Genes ◽

Ppar Gamma ◽

Peroxisome Proliferator ◽

Independent Functions

The peroxisome-proliferator activated receptors (PPARs) have been previously implicated in the pathophysiology of skeletal muscle dysfunction in women with breast cancer (BC) and in animal models of BC. This study investigated alterations induced in skeletal muscle by BC-derived factors in an in vitro conditioned media (CM) system and tested the hypothesis that BC cells secrete a factor that represses PPAR-gamma (PPARG) expression and its transcriptional activity, leading to downregulation of PPARG target genes involved in mitochondrial function and other metabolic pathways. We found that BC-derived factors repress PPAR-mediated transcriptional activity without altering protein expression of PPARG. Further, we show that BC-derived factors induce significant alterations in skeletal muscle mitochondrial function and lipid accumulation, which are rescued with exogenous expression of PPARG. The PPARG agonist drug rosiglitazone was able to rescue BC-induced lipid accumulation, but did not rescue effects of BC-derived factors on PPAR-mediated transcription or mitochondrial function. These data suggest that BC-derived factors alter lipid accumulation and mitochondrial function via different mechanisms that are both related to PPARG signaling, with mitochondrial dysfunction likely being altered via repression of PPAR-mediated transcription, and lipid accumulation being altered via transcription-independent functions of PPARG.

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Mulberry (Morus alba L.) Fruit Extract Ameliorates Inflammation via Regulating MicroRNA-21/132/143 Expression and Increases the Skeletal Muscle Mitochondrial Content and AMPK/SIRT Activities

Antioxidants ◽

10.3390/antiox10091453 ◽

2021 ◽

Vol 10 (9) ◽

pp. 1453

Author(s):

Sunyoon Jung ◽

Mak-Soon Lee ◽

Eugene Chang ◽

Chong-Tai Kim ◽

Yangha Kim

Keyword(s):

Skeletal Muscle ◽

Mitochondrial Dysfunction ◽

Inflammatory Cytokine ◽

Uncoupling Protein ◽

Morus Alba ◽

Macrophage Infiltration ◽

Low Grade ◽

Peroxisome Proliferator ◽

Sprague Dawley ◽

Fruit Extract

The Mulberry (Morus alba L.) fruit is a rich source of polyphenolic compounds; most of these are anthocyanins. Obesity is intimately related to low-grade inflammation, with increased pro-inflammatory cytokine secretion and macrophage infiltration in white adipose tissue (WAT). This study investigated whether mulberry fruit extract (ME) has beneficial effects on obesity-induced inflammation and skeletal muscle mitochondrial dysfunction. Sprague-Dawley rats were divided into four groups and fed either a low-fat diet (LFD), high-fat diet (HFD), HFD + 5 g/kg of ME (ME-L), or HFD + 10 g/kg of ME (ME-H) for 14 weeks. ME alleviated dyslipidemia and lipid accumulation, as well as pro-inflammatory cytokine production such as tumor necrosis factor-α (TNF-α), interleukin 6 (IL-6), and monocyte chemoattractant protein 1 (MCP1) in the WAT. ME mitigated nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) phosphorylation and macrophage infiltration in WAT. Notably, microRNA (miR)-21, miR-132, and miR-43 expressions were downregulated in the WAT of the ME groups compared to the HFD group. Moreover, ME increased the mitochondrial size and mitochondrial DNA (mtDNA) content, as well as key genes’ expression related to mitochondrial function, including sirtuin (SIRT)1, peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), carnitine palmitoyltransferase 1β (CPT-1β), and uncoupling protein 3 (UCP3), and adenosine monophosphate-activated protein kinase (AMPK)/SIRT activities in skeletal muscle. These results suggested that ME might alleviate obesity-induced inflammation and mitochondrial dysfunction by regulating miR-21, miR-132, and miR-43 expression in WAT, and by activating the PGC-1α/SIRT1 pathway in muscle.

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Effects of Rhizome Extract of Dioscorea batatas and Its Active Compound, Allantoin, on the Regulation of Myoblast Differentiation and Mitochondrial Biogenesis in C2C12 Myotubes

Molecules ◽

10.3390/molecules23082023 ◽

2018 ◽

Vol 23 (8) ◽

pp. 2023 ◽

Cited By ~ 16

Author(s):

Junnan Ma ◽

Seok Yong Kang ◽

Xianglong Meng ◽

An Na Kang ◽

Jong Hun Park ◽

...

Keyword(s):

Skeletal Muscle ◽

Glucose Uptake ◽

Mitochondrial Biogenesis ◽

Water Extract ◽

Sirtuin 1 ◽

Myoblast Differentiation ◽

C2c12 Myotubes ◽

Peroxisome Proliferator ◽

Peroxisome Proliferator Activated Receptor ◽

Dioscorea Batatas

With the aging process, a loss of skeletal muscle mass and dysfunction related to metabolic syndrome is observed in older people. Yams are commonly use in functional foods and medications with various effects. The present study was conducted to investigate the effects of rhizome extract of Dioscorea batatas (Dioscoreae Rhizoma, Chinese yam) and its bioactive compound, allantoin, on myoblast differentiation and mitochondrial biogenesis in skeletal muscle cells. Yams were extracted in water and allantoin was analyzed by high performance liquid chromatography (HPLC). The expression of myosin heavy chain (MyHC) and mitochondrial biogenesis-regulating factors, peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), sirtuin-1 (Sirt-1), nuclear respiratory factor-1 (NRF-1) and transcription factor A, mitochondrial (TFAM), and the phosphorylation of AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) were determined in C2C12 myotubes by reverse transcriptase (RT)-polymerase chain reaction (RT-PCR) or western blot. The glucose levels and total ATP contents were measured by glucose consumption, glucose uptake and ATP assays, respectively. Treatment with yam extract (1 mg/mL) and allantoin (0.2 and 0.5 mM) significantly increased MyHC expression compared with non-treated myotubes. Yam extract and allantoin significantly increased the expression of PGC-1α, Sirt-1, NRF-1 and TFAM, as well as the phosphorylation of AMPK and ACC in C2C12 myotubes. Furthermore, yam extract and allantoin significantly increased glucose uptake levels and ATP contents. Finally, HPLC analysis revealed that the yam water extract contained 1.53% of allantoin. Yam extract and allantoin stimulated myoblast differentiation into myotubes and increased energy production through the upregulation of mitochondrial biogenesis regulators. These findings indicate that yam extract and allantoin can help to prevent skeletal muscle dysfunction through the stimulation of the energy metabolism.

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A Class I Histone Deacetylase Inhibitor Attenuates Insulin Resistance and Inflammation in Palmitate-Treated C2C12 Myotubes and Muscle of HF/HFr Diet Mice

Frontiers in Pharmacology ◽

10.3389/fphar.2020.601448 ◽

2020 ◽

Vol 11 ◽

Author(s):

Soo Jin Lee ◽

Sung-E Choi ◽

Han Byeol Lee ◽

Min-Woo Song ◽

Young Ha Kim ◽

...

Keyword(s):

Insulin Resistance ◽

Skeletal Muscle ◽

Histone Deacetylase ◽

Muscle Tissue ◽

Inflammatory Cytokine ◽

Skeletal Muscle Tissue ◽

Class I ◽

C2c12 Myotubes ◽

Peroxisome Proliferator ◽

Hdac Inhibition

Histone deacetylase (HDAC) inhibitors, which regulate gene expression by inhibiting the deacetylation of histones and nonhistone proteins, have been shown to exert a wide array of biological effects; these include anti-cancer, anti-obesity, and anti-diabetes effects, as well as cardiovascular-protective activity. However, the effects of class I HDAC inhibition on lipotoxicity in C2C12 myotubes and skeletal muscle tissue remain poorly understood. In this study, we investigated the molecular mechanism underlying the protective effect of class I HDAC inhibition under lipotoxic conditions, i.e., in palmitate (PA)-treated C2C12 myotubes and skeletal muscle tissue in high fat (HF)/high fructose (HFr) diet mice. PA treatment of C2C12 myotubes increased HDAC3 protein expression and impaired mitochondrial oxidation, resulting in increased mitochondrial ROS generation and an accumulation of intracellular triglycerides (TG). Prolonged exposure led to increased inflammatory cytokine expression and insulin resistance. In contrast, MS-275, a class I HDAC inhibitor, dramatically attenuated lipotoxicity, preventing PA-induced insulin resistance and inflammatory cytokine expression. Similar beneficial effects were also seen following HDAC3 knockdown. In addition, MS-275 increased the mRNA expression of peroxisome proliferator activator receptor γ-coactivator 1α (PGC1α) and mitochondrial transcription factor A (TFAM), which serve as transcriptional coactivators in the context of mitochondrial metabolism and biogenesis, and restored expression of peroxisome proliferator-activated receptor alpha (PPARα), medium-chain acyl-coenzyme A dehydrogenase (MCAD), enoyl-CoA hydratase, and 3-hydroxyacyl CoA dehydrogenase (EHHADH). In vivo, treatment of HF/HFr-fed mice with MS-275 ameliorated hyperglycemia, insulin resistance, stress signals, and TNF-α expression in skeletal muscle. Taken together, these results suggest that HDAC3 inhibition rather than HDAC1/2 inhibition by MS-275 protects against lipotoxicity in C2C12 myotubes and skeletal muscle, and may be effective for the treatment of obesity and insulin resistance.

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