scholarly journals IL-15 Overexpression Promotes Endurance, Oxidative Energy Metabolism, and Muscle PPARδ, SIRT1, PGC-1α, and PGC-1β Expression in Male Mice

Endocrinology ◽  
2013 ◽  
Vol 154 (1) ◽  
pp. 232-245 ◽  
Author(s):  
LeBris S. Quinn ◽  
Barbara G. Anderson ◽  
Jennifer D. Conner ◽  
Tami Wolden-Hanson
Keyword(s):  
Skeletal Muscle ◽  
Insulin Sensitivity ◽  
Energy Metabolism ◽  
Transgenic Mice ◽  
Oxidative Metabolism ◽  
Troponin I ◽  
Expression Patterns ◽  
Sirtuin 1 ◽  
Ppar Γ ◽  
Oxidative Energy Metabolism

Endurance exercise initiates a pattern of gene expression that promotes fat oxidation, which in turn improves endurance, body composition, and insulin sensitivity. The signals from exercise that initiate these pathways have not been completely characterized. IL-15 is a cytokine that is up-regulated in skeletal muscle after exercise and correlates with leanness and insulin sensitivity. To determine whether IL-15 can induce any of the metabolic adaptations associated with exercise, substrate metabolism, endurance, and molecular expression patterns were examined in male transgenic mice with constitutively elevated muscle and circulating IL-15 levels. IL-15 transgenic mice ran twice as long as littermate control mice in a run-to-exhaustion trial and preferentially used fat for energy metabolism. Fast muscles in IL-15 transgenic mice exhibited high expression of intracellular mediators of oxidative metabolism that are induced by exercise, including sirtuin 1, peroxisome proliferator-activated receptor (PPAR)-δ, PPAR-γ coactivator-1α, and PPAR-γ coactivator-1β. Muscle tissue in IL-15 transgenic mice exhibited myosin heavy chain and troponin I mRNA isoform expression patterns indicative of a more oxidative phenotype than controls. These findings support a role for IL-15 in induction of exercise endurance, oxidative metabolism, and skeletal muscle molecular adaptations induced by physical training.

scholarly journals Fast skeletal muscle-specific expression of a quail troponin I gene in transgenic mice.

1988 ◽  
Vol 8 (12) ◽  
pp. 5072-5079 ◽  
Author(s):  
P L Hallauer ◽  
K E Hastings ◽  
A C Peterson
Keyword(s):  
Skeletal Muscle ◽  
Transgenic Mice ◽  
Troponin I ◽  
Fiber Type ◽  
Regulatory Elements ◽  
Evolutionary Divergence ◽  
Mrna Levels ◽  
Fast Skeletal Muscle ◽  
Specific Expression ◽  
Exon 2

We have produced seven lines of transgenic mice carrying the quail gene encoding the fast skeletal muscle-specific isoform of troponin I (TnIf). The quail DNA included the entire TnIf gene, 530 base pairs of 5'-flanking DNA, and 1.5 kilobase pairs of 3'-flanking DNA. In all seven transgenic lines, normally initiated and processed quail TnIf mRNA was expressed in skeletal muscle, where it accumulated to levels comparable to that in quail muscle. Moreover, in the three lines tested, quail TnIf mRNA levels were manyfold higher in a fast skeletal muscle (gastrocnemius) than in a slow skeletal muscle (soleus). We conclude that the cellular mechanisms directing muscle fiber type-specific TnIf gene expression are mediated by cis-regulatory elements present on the introduced quail DNA fragment and that they control TnIf expression by affecting the accumulation of TnIf mRNA. These elements have been functionally conserved since the evolutionary divergence of birds and mammals, despite the major physiological and morphological differences existing between avian (tonic) and mammalian (twitch) slow muscles. In lines of transgenic mice carrying multiple tandemly repeated copies of the transgene, an aberrant quail TnIf transcript (differing from normal TnIf mRNA upstream of exon 2) also accumulated in certain tissues, particularly lung, brain, spleen, and heart tissues. However, this aberrant transcript was not detected in a transgenic line which carries only a single copy of the quail gene.

scholarly journals Nicotinamide riboside supplementation alters body composition and skeletal muscle acetylcarnitine concentrations in healthy obese humans

2020 ◽  
Vol 112 (2) ◽  
pp. 413-426 ◽  
Author(s):  
Carlijn M E Remie ◽  
Kay H M Roumans ◽  
Michiel P B Moonen ◽  
Niels J Connell ◽  
Bas Havekes ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Body Composition ◽  
Insulin Sensitivity ◽  
Energy Metabolism ◽  
Mitochondrial Function ◽  
Dry Weight ◽  
Metabolic Health ◽  
Men And Women ◽  
Nicotinamide Riboside ◽  
Wet Weight

ABSTRACT Background Nicotinamide riboside (NR) is an NAD+ precursor that boosts cellular NAD+ concentrations. Preclinical studies have shown profound metabolic health effects after NR supplementation. Objectives We aimed to investigate the effects of 6 wk NR supplementation on insulin sensitivity, mitochondrial function, and other metabolic health parameters in overweight and obese volunteers. Methods A randomized, double-blinded, placebo-controlled, crossover intervention study was conducted in 13 healthy overweight or obese men and women. Participants received 6 wk NR (1000 mg/d) and placebo supplementation, followed by broad metabolic phenotyping, including hyperinsulinemic-euglycemic clamps, magnetic resonance spectroscopy, muscle biopsies, and assessment of ex vivo mitochondrial function and in vivo energy metabolism. Results Markers of increased NAD+ synthesis—nicotinic acid adenine dinucleotide and methyl nicotinamide—were elevated in skeletal muscle after NR compared with placebo. NR increased body fat-free mass (62.65% ± 2.49% compared with 61.32% ± 2.58% in NR and placebo, respectively; change: 1.34% ± 0.50%, P = 0.02) and increased sleeping metabolic rate. Interestingly, acetylcarnitine concentrations in skeletal muscle were increased upon NR (4558 ± 749 compared with 3025 ± 316 pmol/mg dry weight in NR and placebo, respectively; change: 1533 ± 683 pmol/mg dry weight, P = 0.04) and the capacity to form acetylcarnitine upon exercise was higher in NR than in placebo (2.99 ± 0.30 compared with 2.40 ± 0.33 mmol/kg wet weight; change: 0.53 ± 0.21 mmol/kg wet weight, P = 0.01). However, no effects of NR were found on insulin sensitivity, mitochondrial function, hepatic and intramyocellular lipid accumulation, cardiac energy status, cardiac ejection fraction, ambulatory blood pressure, plasma markers of inflammation, or energy metabolism. Conclusions NR supplementation of 1000 mg/d for 6 wk in healthy overweight or obese men and women increased skeletal muscle NAD+ metabolites, affected skeletal muscle acetylcarnitine metabolism, and induced minor changes in body composition and sleeping metabolic rate. However, no other metabolic health effects were observed. This trial was registered at clinicaltrials.gov as NCT02835664

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

Endocrinology ◽  
2016 ◽  
Vol 157 (6) ◽  
pp. 2259-2269 ◽  
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.

scholarly journals Peroxisome Proliferator-Activated Receptor -β/δ, -γAgonists and Resveratrol Modulate Hypoxia Induced Changes in Nuclear Receptor Activators of Muscle Oxidative Metabolism

PPAR Research ◽  
2010 ◽  
Vol 2010 ◽  
pp. 1-13 ◽  
Author(s):  
Timothy R. H. Regnault ◽  
Lin Zhao ◽  
Jacky S. S. Chiu ◽  
Stephanie K. Gottheil ◽  
Allison Foran ◽  
...  
Keyword(s):  
Insulin Sensitivity ◽  
Oxidative Metabolism ◽  
Intrauterine Growth Restriction ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Ppar Γ ◽  
Hypoxia Adaptation ◽  
Induced Changes ◽  
Ppar Pathway

PPAR-α, PPAR-β, and PPAR-γ, and RXR in conjunction with PGC-1α and SIRT1, activate oxidative metabolism genes determining insulin sensitivity. In utero, hypoxia is commonly observed in Intrauterine Growth Restriction (IUGR), and reduced insulin sensitivity is often observed in these infants as adults. We sought to investigate how changes in oxygen tension might directly impact muscle PPAR regulation of oxidative genes. Following eight days in culture at 1% oxygen, C2C12muscle myoblasts displayed a reduction of PGC-1α, PPAR-α, and RXR-α mRNA, as well as CPT-1b and UCP-2 mRNA. SIRT1 and PGC-1α protein was reduced, and PPAR-γ protein increased. The addition of a PPAR-β agonist (L165,041) for the final 24 hours of 1% treatment resulted in increased levels of UCP-2 mRNA and protein whereas Rosiglitazone induced SIRT1, PGC-1α, RXR-α, PPAR-α, CPT-1b, and UCP-2 mRNA and SIRT1 protein. Under hypoxia, Resveratrol induced SIRT1, RXR-α, PPAR-α mRNA, and PPAR-γ and UCP-2 protein. These findings demonstrate that hypoxia alters the components of the PPAR pathway involved in muscle fatty acid oxidative gene transcription and translation. These results have implications for understanding selective hypoxia adaptation and how it might impact long-term muscle oxidative metabolism and insulin sensitivity.

scholarly journals HSP72 Is a Mitochondrial Stress Sensor Critical for Parkin Action, Oxidative Metabolism, and Insulin Sensitivity in Skeletal Muscle

Diabetes ◽  
2013 ◽  
Vol 63 (5) ◽  
pp. 1488-1505 ◽  
Author(s):  
Brian G. Drew ◽  
Vicente Ribas ◽  
Jamie A. Le ◽  
Darren C. Henstridge ◽  
Jennifer Phun ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Insulin Sensitivity ◽  
Oxidative Metabolism ◽  
Mitochondrial Stress ◽  
Stress Sensor

scholarly journals cis-acting sequences of the rat troponin I slow gene confer tissue- and development-specific transcription in cultured muscle cells as well as fiber type specificity in transgenic mice.

1993 ◽  
Vol 13 (11) ◽  
pp. 7019-7028 ◽  
Author(s):  
S Banerjee-Basu ◽  
A Buonanno
Keyword(s):  
Skeletal Muscle ◽  
Transgenic Mice ◽  
Transcription Initiation ◽  
Troponin I ◽  
Regulatory Elements ◽  
Initiation Site ◽  
C2c12 Cells ◽  
Fiber Types ◽  
Tibialis Muscle ◽  
Flanking Sequences

Transcription of the genes coding for troponin I slow (TnIslow) and other contractile proteins is activated during skeletal muscle differentiation, and their expression is later restricted to specific fiber types during maturation. We have isolated and characterized the rat TnIslow gene in order to begin elucidating its regulation during myogenesis. Transcriptional regulatory regions were delineated by using constructs, containing TnIslow gene sequences driving the expression of the chloramphenicol acetyltransferase (CAT) reporter gene, that were transiently transfected into undifferentiated and differentiated C2C12 cells. TnIslow 5'-flanking sequences directed transcription specifically in differentiated cells. However, transcription rates were approximately 10-fold higher in myotubes transfected with constructs containing the 5'-flanking sequences plus the intragenic region residing upstream of the translation initiation site (introns 1 and 2), indicative of interactions between elements residing upstream and in the introns of the gene. Deletion analysis of the 5' region of the TnIslow gene showed that the 200 bp upstream of the transcription initiation site is sufficient to confer differentiation-specific transcription in C2C12 myocytes. MyoD consensus binding sites were found both in the upstream 200-bp region and in a region residing in the second intron that is highly homologous to the quail TnIfast enhancer. Transactivation experiments using transfected NIH 3T3 fibroblasts with TnI-CAT constructs containing intragenic and/or upstream sequences and with the myogenic factors MyoD, myogenin, and MRF4 showed different potentials of these factors to induce transcription. Transgenic mice harboring the rat TnI-CAT fusion gene expressed the reporter specifically in the skeletal muscle. Furthermore, CAT levels were approximately 50-fold higher in the soleus than in the extensor digitorum longus, gastrocnemius, or tibialis muscle, indicating that the regulatory elements that restrict TnI transcription to slow-twitch myofibers reside in the sequences we have analyzed.

scholarly journals Low-Frequency Electroacupuncture Improves Insulin Sensitivity in Obese Diabetic Mice through Activation of SIRT1/PGC-1αin Skeletal Muscle

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Fengxia Liang ◽  
Rui Chen ◽  
Atsushi Nakagawa ◽  
Makoto Nishizawa ◽  
Shinichi Tsuda ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Insulin Sensitivity ◽  
Fasting Blood Glucose ◽  
Low Frequency ◽  
Tolerance Test ◽  
Sirtuin 1 ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Obesity And Diabetes

Electroacupuncture (EA) has been observed to reduce insulin resistance in obesity and diabetes. However, the biochemical mechanism underlying this effect remains unclear. This study investigated the effects of low-frequency EA on metabolic action in genetically obese and type 2 diabetic db/db mice. Nine-week-old db/m and db/db mice were randomly divided into four groups, namely, db/m, db/m + EA, db/db, and db/db + EA. db/m + EA and db/db + EA mice received 3-Hz electroacupuncture five times weekly for eight consecutive weeks. In db/db mice, EA tempered the increase in fasting blood glucose, food intake, and body mass and maintained insulin levels. In EA-treated db/db mice, improved insulin sensitivity was established through intraperitoneal insulin tolerance test. EA was likewise observed to decrease free fatty acid levels in db/db mice; it increased protein expression in skeletal muscle Sirtuin 1 (SIRT1) and induced gene expression of peroxisome proliferator-activated receptor coactivator (PGC-), nuclear respiratory factor 1 (NRF1), and acyl-CoA oxidase (ACOX). These results indicated that EA offers a beneficial effect on insulin resistance in obese and diabetic db/db mice, at least partly, via stimulation of SIRT1/PGC-, thus resulting in improved insulin signal.

scholarly journals PGC-1α regulation by exercise training and its influences on muscle function and insulin sensitivity

2010 ◽  
Vol 299 (2) ◽  
pp. E145-E161 ◽  
Author(s):  
Vitor A. Lira ◽  
Carley R. Benton ◽  
Zhen Yan ◽  
Arend Bonen
Keyword(s):  
Skeletal Muscle ◽  
Insulin Sensitivity ◽  
Transgenic Mice ◽  
Mitochondrial Biogenesis ◽  
Therapeutic Potential ◽  
Fiber Type ◽  
Acid Oxidation ◽  
Physiological Limits ◽  
Exercise Induced

The peroxisome proliferator-activated receptor-γ (PPARγ) coactivator-1α (PGC-1α) is a major regulator of exercise-induced phenotypic adaptation and substrate utilization. We provide an overview of 1) the role of PGC-1α in exercise-mediated muscle adaptation and 2) the possible insulin-sensitizing role of PGC-1α. To these ends, the following questions are addressed. 1) How is PGC-1α regulated, 2) what adaptations are indeed dependent on PGC-1α action, 3) is PGC-1α altered in insulin resistance, and 4) are PGC-1α-knockout and -transgenic mice suitable models for examining therapeutic potential of this coactivator? In skeletal muscle, an orchestrated signaling network, including Ca2+-dependent pathways, reactive oxygen species (ROS), nitric oxide (NO), AMP-dependent protein kinase (AMPK), and p38 MAPK, is involved in the control of contractile protein expression, angiogenesis, mitochondrial biogenesis, and other adaptations. However, the p38γ MAPK/PGC-1α regulatory axis has been confirmed to be required for exercise-induced angiogenesis and mitochondrial biogenesis but not for fiber type transformation. With respect to a potential insulin-sensitizing role of PGC-1α, human studies on type 2 diabetes suggest that PGC-1α and its target genes are only modestly downregulated (≤34%). However, studies in PGC-1α-knockout or PGC-1α-transgenic mice have provided unexpected anomalies, which appear to suggest that PGC-1α does not have an insulin-sensitizing role. In contrast, a modest (∼25%) upregulation of PGC-1α, within physiological limits, does improve mitochondrial biogenesis, fatty acid oxidation, and insulin sensitivity in healthy and insulin-resistant skeletal muscle. Taken altogether, there is substantial evidence that the p38γ MAPK-PGC-1α regulatory axis is critical for exercise-induced metabolic adaptations in skeletal muscle, and strategies that upregulate PGC-1α, within physiological limits, have revealed its insulin-sensitizing effects.

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