scholarly journals Skeletal Muscle mTORC1 Activation Increases Energy Expenditure and Reduces Longevity in Mice

2019 ◽  
Author(s):  
Erin J. Stephenson ◽  
JeAnna R. Redd ◽  
Detrick Snyder ◽  
Quynh T. Tran ◽  
Binbin Lu ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Energy Expenditure ◽  
High Fat Diet ◽  
High Fat ◽  
Constitutive Activation ◽  
Mechanistic Target Of Rapamycin ◽  
Systemic Insulin Resistance ◽  
Mtorc1 Signaling ◽  
Futile Cycling ◽  
Mtorc1 Activation

AbstractThe mechanistic target of rapamycin (mTORC1) is a nutrient responsive protein kinase complex that helps co-ordinate anabolic processes across all tissues. There is evidence that signaling through mTORC1 in skeletal muscle may be a determinant of energy expenditure and aging and therefore components downstream of mTORC1 signaling may be potential targets for treating obesity and age-associated metabolic disease. Here, we generated mice with Ckmm-Cre driven ablation of Tsc1, which confers constitutive activation of mTORC1 in skeletal muscle and performed unbiased transcriptional analyses to identify pathways and candidate genes that may explain how skeletal muscle mTORC1 activity regulates energy balance and aging. Activation of skeletal muscle mTORC1 produced a striking resistance to diet-and age-induced obesity without inducing systemic insulin resistance. We found that increases in energy expenditure following a high fat diet were mTORC1-dependent and that elevated energy expenditure caused by ablation of Tsc1 coincided with the upregulation of skeletal muscle-specific thermogenic mechanisms that involve sarcolipin-driven futile cycling of Ca2+ through SERCA2. Additionally, we report that constitutive activation of mTORC1 in skeletal muscle reduces lifespan. These findings support the hypothesis that activation of mTORC1 and its downstream targets, specifically in skeletal muscle, may play a role in nutrient-dependent thermogenesis and aging.

Abstract 394: Posttranslational Modification Of Klf5 Mediates Metabolic Dysfunction And Vascular Disease In Metabolic Syndrome

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Yumiko Oishi ◽  
Ichiro Manabe ◽  
Kazuyuki Tobe ◽  
Takashi Kadowaki ◽  
Ryozo Nagai
Keyword(s):  
Skeletal Muscle ◽  
Metabolic Syndrome ◽  
Energy Expenditure ◽  
Posttranslational Modifications ◽  
High Fat Diet ◽  
Metabolic Diseases ◽  
C2c12 Myotubes ◽  
Metabolic Dysfunction ◽  
High Fat ◽  
Increased Risk

We have previously shown that a zinc finger transcription factor, Krüppel-like factor 5 (KLF5), plays an important role in pathogenesis of cardiovascular diseases, such as atherosclerosis. KLF5 heterozygous knockout ( KLF5 +/ − ) mice exhibited much less neointima formation, cardiac hypertrophy and fibrosis. We also found that expression of KLF5 correlated with a higher incidence of restenosis following PCI and the SNP located within the KLF5 promoter was associated with an increased risk of hypertension in man. Interestingly, KLF5 is also expressed in metabolic tissues such as adipose tissue, skeletal muscle, and pancreatic β-cells. Thus, we hypothesized that KLF5 might play a role in metabolic diseases. To test this, KLF5 +/ − mice were fed with high-fat diet. Although KLF5 +/ − mice ate more food than wild-type littermates, they were resistant to high-fat diet-induced obesity and protected from dyslipidemia, glucose intolerance and hepatic steatosis, indicating that KLF5 + /− mice were less susceptible to metabolic syndrome. The systemic O 2 consumption and expression of genes involved in energy expenditure in skeletal muscle were increased in KLF5 + /− mice, demonstrating enhanced energy expenditure, which partly explains the phenotype. Knocking down KLF5 by siRNA increased expression levels of UCP2/3 and CPT-1b in C2C12 myotubes, suggesting that KLF5 may inhibit energy expenditure-related genes. Chromatin immunoprecipitation and coimmunoprecipitation assays showed that KLF5 interacted with corepressors, such as SMRT and NCoR, and strongly inhibited the UCP and CPT-1b promoters. We found that this inhibitory activity of KLF5 depended on its SUMOylation. When KLF5 was deSUMOylated, it activated the promoters. These data demonstrate that KLF5 acts as a molecular switch for energy expenditure and the posttranslational modifications of KLF5 including SUMOylation turns on/off the switch function of KLF5. Given that KLF5 also controls tissue remodeling in response to external stress, KLF5 may mediate metabolic dysfunction and atherosclerosis in metabolic syndrome. Our findings also suggest that the posttranscriptional modification of KLF5 is an attractive novel therapeutic target.

scholarly journals Shift in metabolic fuel in acylation-stimulating protein-deficient mice following a high-fat diet

2008 ◽  
Vol 294 (6) ◽  
pp. E1051-E1059 ◽  
Author(s):  
Christian Roy ◽  
Sabina Paglialunga ◽  
Alexandre Fisette ◽  
Patrick Schrauwen ◽  
Esther Moonen-Kornips ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Fatty Acid ◽  
Energy Expenditure ◽  
High Fat Diet ◽  
Ex Vivo ◽  
Direct Result ◽  
Acid Oxidation ◽  
High Fat ◽  
Metabolic Potential ◽  
Deficient Mice

ASP-deficient mice (C3 KO) have delayed postprandial TG clearance, are hyperphagic, and display increased energy expenditure. Markers of carbohydrate and fatty acid metabolism in the skeletal muscle and heart were examined to evaluate the mechanism. On a high-fat diet, compared with wild-type mice, C3 KO mice have increased energy expenditure, decreased RQ, lower ex vivo glucose oxidation (−39%, P = 0.018), and higher ex vivo fatty acid oxidation (+68%, P = 0.019). They have lower muscle glycogen content (−25%, P < 0.05) and lower activities for the glycolytic enzymes glycogen phosphorylase (−31%, P = 0.005), hexokinase (−43%, P = 0.007), phosphofructokinase (−51%, P < 0.0001), and GAPDH (−15%, P = 0.04). Analysis of mitochondrial enzyme activities revealed that hydroxyacyl-coenzyme A dehydrogenase was higher (+25%, P = 0.004) in C3 KO mice. Furthermore, Western blot analysis of muscle revealed significantly higher fatty acid transporter CD36 (+40%, P = 0.006) and cytochrome c (a marker of mitochondrial content; +69%, P = 0.034) levels in C3 KO mice, whereas the activity of AMP kinase was lower (−48%, P = 0.003). Overall, these results demonstrate a shift in the metabolic potential of skeletal muscle toward increased fatty acid utilization. Whether this is 1) a consequence of decreased adipose tissue storage with repartitioning toward muscle or 2) a direct result of the absence of ASP interaction with the receptor C5L2 in muscle remains to be determined. However, these in vivo data suggest that ASP inhibition could be a potentially viable approach in correcting muscle metabolic dysfunction in obesity.

scholarly journals Anti-Obesity and Anti-Diabetic Effects of Acacia Polyphenol in Obese Diabetic KKAy Mice Fed High-Fat Diet

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
Nobutomo Ikarashi ◽  
Takahiro Toda ◽  
Takehiro Okaniwa ◽  
Kiyomi Ito ◽  
Wataru Ochiai ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Body Weight ◽  
Adipose Tissue ◽  
Energy Expenditure ◽  
White Adipose Tissue ◽  
High Fat Diet ◽  
Acid Synthesis ◽  
Diet Group ◽  
High Fat ◽  
Kkay Mice

Acacia polyphenol (AP) extracted from the bark of the black wattle tree (Acacia meansii) is rich in unique catechin-like flavan-3-ols, such as robinetinidol and fisetinidol. The present study investigated the anti-obesity/anti-diabetic effects of AP using obese diabetic KKAy mice. KKAy mice received either normal diet, high-fat diet or high-fat diet with additional AP for 7 weeks. After the end of administration, body weight, plasma glucose and insulin were measured. Furthermore, mRNA and protein expression of obesity/diabetic suppression-related genes were measured in skeletal muscle, liver and white adipose tissue. As a result, compared to the high-fat diet group, increases in body weight, plasma glucose and insulin were significantly suppressed for AP groups. Furthermore, compared to the high-fat diet group, mRNA expression of energy expenditure-related genes (PPARα, PPARδ, CPT1, ACO and UCP3) was significantly higher for AP groups in skeletal muscle. Protein expressions of CPT1, ACO and UCP3 for AP groups were also significantly higher when compared to the high-fat diet group. Moreover, AP lowered the expression of fat acid synthesis-related genes (SREBP-1c, ACC and FAS) in the liver. AP also increased mRNA expression of adiponectin and decreased expression of TNF-αin white adipose tissue. In conclusion, the anti-obesity actions of AP are considered attributable to increased expression of energy expenditure-related genes in skeletal muscle, and decreased fatty acid synthesis and fat intake in the liver. These results suggest that AP is expected to be a useful plant extract for alleviating metabolic syndrome.

scholarly journals Constitutive activation of CaMKKα signaling is sufficient but not necessary for mTORC1 activation and growth in mouse skeletal muscle

2014 ◽  
Vol 307 (8) ◽  
pp. E686-E694 ◽  
Author(s):  
Jeremie L. A. Ferey ◽  
Jeffrey J. Brault ◽  
Cheryl A. S. Smith ◽  
Carol A. Witczak
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Knockout Mice ◽  
Muscle Growth ◽  
Mouse Muscle ◽  
Constitutive Activation ◽  
Mouse Skeletal Muscle ◽  
Mtorc1 Signaling ◽  
Mtorc1 Activation ◽  
Constitutively Active

Skeletal muscle loading/overload stimulates the Ca2+-activated, serine/threonine kinase Ca2+/calmodulin-dependent protein kinase kinase-α (CaMKKα); yet to date, no studies have examined whether CaMKKα regulates muscle growth. The purpose of this study was to determine if constitutive activation of CaMKKα signaling could stimulate muscle growth and if so whether CaMKKα is essential for this process. CaMKKα signaling was selectively activated in mouse muscle via expression of a constitutively active form of CaMKKα using in vivo electroporation. After 2 wk, constitutively active CaMKKα expression increased muscle weight (∼10%) and protein content (∼10%), demonstrating that activation of CaMKKα signaling can stimulate muscle growth. To determine if active CaMKKα expression stimulated muscle growth via increased mammalian target of rapamycin complex 1 (mTORC1) signaling and protein synthesis, [3H]phenylalanine incorporation into proteins was assessed with or without the mTORC1 inhibitor rapamycin. Constitutively active CaMKKα increased protein synthesis ∼60%, and this increase was prevented by rapamycin, demonstrating a critical role for mTORC1 in this process. To determine if CaMKKα is essential for growth, muscles from CaMKKα knockout mice were stimulated to hypertrophy via unilateral ablation of synergist muscles (overload). Surprisingly, compared with wild-type mice, muscles from CaMKKα knockout mice exhibited greater growth (∼15%) and phosphorylation of the mTORC1 substrate 70-kDa ribosomal protein S6 kinase (Thr389; ∼50%), demonstrating that CaMKKα is not essential for overload-induced mTORC1 activation or muscle growth. Collectively, these results demonstrate that activation of CaMKKα signaling is sufficient but not necessary for activation of mTORC1 signaling and growth in mouse skeletal muscle.

scholarly journals Germline or inducible knockout of p300 or CBP in skeletal muscle does not alter insulin sensitivity

2019 ◽  
Vol 316 (6) ◽  
pp. E1024-E1035 ◽  
Author(s):  
Vitor F. Martins ◽  
Jessica R. Dent ◽  
Kristoffer Svensson ◽  
Shahriar Tahvilian ◽  
Maedha Begur ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Insulin Sensitivity ◽  
Energy Expenditure ◽  
Glucose Tolerance ◽  
High Fat Diet ◽  
Binding Protein ◽  
Oral Glucose ◽  
Oral Glucose Tolerance ◽  
High Fat ◽  
Skeletal Muscle Insulin Sensitivity

Akt is a critical mediator of insulin-stimulated glucose uptake in skeletal muscle. The acetyltransferases, E1A binding protein p300 (p300) and cAMP response element-binding protein binding protein (CBP) are phosphorylated and activated by Akt, and p300/CBP can acetylate and inactivate Akt, thus giving rise to a possible Akt-p300/CBP axis. Our objective was to determine the importance of p300 and CBP to skeletal muscle insulin sensitivity. We used Cre-LoxP methodology to generate mice with germline [muscle creatine kinase promoter (P-MCK and C-MCK)] or inducible [tamoxifen-activated, human skeletal actin promoter (P-iHSA and C-iHSA)] knockout of p300 or CBP. A subset of P-MCK and C-MCK mice were switched to a calorie-restriction diet (60% of ad libitum intake) or high-fat diet at 10 wk of age. For P-iHSA and C-iHSA mice, knockout was induced at 10 wk of age. At 13–15 wk of age, we measured whole-body energy expenditure, oral glucose tolerance, and/or ex vivo skeletal muscle insulin sensitivity. Although p300 and CBP protein abundance and mRNA expression were reduced 55%–90% in p300 and CBP knockout mice, there were no genotype differences in energy expenditure or fasting glucose and insulin concentrations. Moreover, neither loss of p300 or CBP impacted oral glucose tolerance or skeletal muscle insulin sensitivity, nor did their loss impact alterations in these parameters in response to a calorie restriction or high-fat diet. Muscle-specific loss of either p300 or CBP, be it germline or in adulthood, does not impact energy expenditure, glucose tolerance, or skeletal muscle insulin action.

scholarly journals Altered nutrient response of mTORC1 as a result of changes in REDD1 expression: effect of obesity vs. REDD1 deficiency

2014 ◽  
Vol 117 (3) ◽  
pp. 246-256 ◽  
Author(s):  
David L. Williamson ◽  
Zhuyun Li ◽  
Rubin M. Tuder ◽  
Elena Feinstein ◽  
Scot R. Kimball ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
High Fat Diet ◽  
Wild Type ◽  
High Fat ◽  
Low Fat ◽  
Mouse Muscle ◽  
Nutrient Response ◽  
Diet Induced Obesity ◽  
Mtorc1 Signaling

Although aberrant mTORC1 signaling has been well established in models of obesity, little is known about its repressor, REDD1. Therefore, the initial goal of this study was to determine the role of REDD1 on mTORC1 in obese skeletal muscle. REDD1 expression (protein and message) and mTORC1 signaling (S6K1, 4E-BP1, raptor-mTOR association, Rheb GTP) were examined in lean vs. ob/ob and REDD1 wild-type (WT) vs. knockout (KO) mice, under conditions of altered nutrient intake [fasted and fed or diet-induced obesity (10% vs. 60% fat diet)]. Despite higher ( P < 0.05) S6K1 and 4E-BP1 phosphorylation, two models of obesity ( ob/ob and diet-induced) displayed elevated ( P < 0.05) skeletal muscle REDD1 expression compared with lean or low-fat-fed mouse muscle under fasted conditions. The ob/ob mice displayed elevated REDD1 expression ( P < 0.05) that coincided with aberrant mTORC1 signaling (hyperactive S6K1, low raptor-mTOR binding, elevated Rheb GTP; P < 0.05) under fasted conditions, compared with the lean, which persisted in a dysregulated fashion under fed conditions. REDD1 KO mice gained limited body mass on a high-fat diet, although S6K1 and 4E-BP1 phosphorylation remained elevated ( P < 0.05) in both the low-fat and high-fat-fed KO vs. WT mice. Similarly, the REDD1 KO mouse muscle displayed blunted mTORC1 signaling responses (S6K1 and 4E-BP1, raptor-mTOR binding) and circulating insulin under fed conditions vs. the robust responses ( P < 0.05) in the WT fed mouse muscle. These studies suggest that REDD1 in skeletal muscle may serve to limit hyperactive mTORC1, which promotes aberrant mTORC1 signaling responses during altered nutrient states.

High-fat diet differentially regulates metabolic parameters in obesity-resistant S5B/Pl rats and obesity-prone Osborne-Mendel rats

2016 ◽  
Vol 94 (2) ◽  
pp. 206-215 ◽  
Author(s):  
Timothy D. Allerton ◽  
Stefany D. Primeaux
Keyword(s):  
Skeletal Muscle ◽  
Energy Expenditure ◽  
Metabolic Rate ◽  
Lipid Accumulation ◽  
High Fat Diet ◽  
Gastrocnemius Muscle ◽  
Metabolic Parameters ◽  
Current Experiment ◽  
High Fat ◽  
Pparγ Expression

The current experiment tested the hypothesis that consumption of a high-fat diet (HFD) would differentially affect metabolic parameters in obesity-prone Osborne-Mendel (OM) and obesity-resistant S5B/Pl (S5B) rats. In OM rats consuming a HFD, an increase in HFD intake, body mass, and percent fat mass, and a HFD-induced decrease in metabolic rate and energy expenditure were demonstrated. In S5B rats consuming a HFD, no change in percent body fat or HFD intake was demonstrated and HFD increased metabolic rate and energy expenditure. To assess whether HFD differentially altered skeletal muscle markers of metabolism in OM and S5B rats, the expression of the transporters, CD36 and GLUT4, and the energy sensors, AMPK and PPARγ, in the gastrocnemius muscle was measured. Oxidation and lipid accumulation in the gastrocnemius muscle was histologically determined. Consumption of a HFD decreased phosphorylated AMPK and PPARγ expression in the skeletal muscle of obesity-prone OM rats. Lipid accumulation in skeletal muscle was significantly higher in OM rats fed a HFD. Overall, these data suggest that the differential response to HFD on metabolic rate, energy expenditure, and phosphorylated AMPK and PPARγ in OM and S5B rats, may partially account for differences in the susceptibility to develop obesity.

scholarly journals High-fat diet-induced impairment of skeletal muscle insulin sensitivity is not prevented by SIRT1 overexpression

2014 ◽  
Vol 307 (9) ◽  
pp. E764-E772 ◽  
Author(s):  
Amanda T. White ◽  
Andrew Philp ◽  
Heidi N. Fridolfsson ◽  
Jan M. Schilling ◽  
Anne N. Murphy ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Energy Expenditure ◽  
Glucose Tolerance ◽  
Glucose Uptake ◽  
High Fat Diet ◽  
Sirtuin 1 ◽  
Whole Body ◽  
Oral Glucose ◽  
High Fat

Skeletal muscle sirtuin 1 (SIRT1) expression is reduced under insulin-resistant conditions, such as those resulting from high-fat diet (HFD) feeding and obesity. Herein, we investigated whether constitutive activation of SIRT1 in skeletal muscle prevents HFD-induced muscle insulin resistance. To address this, mice with muscle-specific overexpression of SIRT1 (mOX) and wild-type (WT) littermates were fed a control diet (10% calories from fat) or HFD (60% of calories from fat) for 12 wk. Magnetic resonance imaging and indirect calorimetry were used to measure body composition and energy expenditure, respectively. Whole body glucose metabolism was assessed by oral glucose tolerance test, and insulin-stimulated glucose uptake was measured at a physiological insulin concentration in isolated soleus and extensor digitorum longus muscles. Although SIRT1 was significantly overexpressed in muscle of mOX vs. WT mice, body weight and percent body fat were similarly increased by HFD for both genotypes, and energy expenditure was unaffected by diet or genotype. Importantly, impairments in glucose tolerance and insulin-mediated activation of glucose uptake in skeletal muscle that occurred with HFD feeding were not prevented in mOX mice. In contrast, mOX mice showed enhanced postischemic cardiac functional recovery compared with WT mice, confirming the physiological functionality of the SIRT1 transgene in this mouse model. Together, these results demonstrate that activation of SIRT1 in skeletal muscle alone does not prevent HFD-induced glucose intolerance, weight gain, or insulin resistance.

Sign in / Sign up

Export Citation Format

Share Document