scholarly journals Evidence for a neuromuscular circuit involving hypothalamic Interleukin-6 signaling in the control of skeletal muscle metabolism

Author(s):  
Carlos Katashima ◽  
Thayana Micheletti ◽  
Alexandre Moura-Assis ◽  
Rodrigo Gaspar ◽  
Ludger Goeminne ◽  
...  

Abstract Hypothalamic interleukin-6 (IL6) exerts a broad metabolic control, including energy expenditure1, food consumption2, glucose homeostasis2, etc. Here we demonstrated that Interleukin-6 (IL6) activates the ERK1/2 pathway in the ventromedial hypothalamus (VMH), stimulating AMPK/ACC signaling and fatty acid oxidation in mice skeletal muscle. Bioinformatics analysis revealed that the hypothalamic IL6/ERK1-2 axis is closely associated with firing-rate-related genes in the hypothalamus and with fatty acid oxidation- and mitochondrial-related genes in skeletal muscle of genetically diverse BXD mice strains and humans. Using surgical denervation, pharmacological approaches, and transgenic mice, we showed that the hypothalamic IL6/ERK1/2 pathway requires the a2-adrenergic pathway to modify the fatty acid skeletal muscle metabolism. To address the physiological relevance of these findings, we demonstrated that this neuromuscular circuitry is required to underpin AMPK/ACC signaling activation and fatty acid oxidation post-exercise. Once the selective downregulation of IL6 receptor in VMH abolished the effects of exercise to sustain AMPK and ACC phosphorylation and fatty acid oxidation in the muscle post-exercise. Altogether, these data demonstrated that IL6/ERK axis in VMH controls fatty acid metabolism in mice skeletal muscle.

2008 ◽  
Vol 194 (4) ◽  
pp. 293-309 ◽  
Author(s):  
G. P. Holloway ◽  
J. J. F. P. Luiken ◽  
J. F. C. Glatz ◽  
L. L. Spriet ◽  
A. Bonen

Diabetes ◽  
2006 ◽  
Vol 55 (10) ◽  
pp. 2688-2697 ◽  
Author(s):  
A. L. Carey ◽  
G. R. Steinberg ◽  
S. L. Macaulay ◽  
W. G. Thomas ◽  
A. G. Holmes ◽  
...  

Author(s):  
Hyo-Bum Kwak ◽  
Tracey Woodlief ◽  
Thomas Green ◽  
Julie Cox ◽  
Robert Hickner ◽  
...  

In rodent skeletal muscle, acyl-coenzyme A (CoA) synthetase 5 (ACSL-5) is suggested to localize to the mitochondria but its precise function in human skeletal muscle is unknown. The purpose of these studies was to define the role of ACSL-5 in mitochondrial fatty acid metabolism and the potential effects on insulin action in human skeletal muscle cells (HSKMC). Primary myoblasts isolated from vastus lateralis (obese women (body mass index (BMI) = 34.7 ± 3.1 kg/m2)) were transfected with ACSL-5 plasmid DNA or green fluorescent protein (GFP) vector (control), differentiated into myotubes, and harvested (7 days). HSKMC were assayed for complete and incomplete fatty acid oxidation ([1-14C] palmitate) or permeabilized to determine mitochondrial respiratory capacity (basal (non-ADP stimulated state 4), maximal uncoupled (carbonyl cyanide-4-(trifluoromethoxy)phenylhydrazone (FCCP)-linked) respiration, and free radical (superoxide) emitting potential). Protein levels of ACSL-5 were 2-fold higher in ACSL-5 overexpressed HSKMC. Both complete and incomplete fatty acid oxidation increased by 2-fold (p < 0.05). In permeabilized HSKMC, ACSL-5 overexpression significantly increased basal and maximal uncoupled respiration (p < 0.05). Unexpectedly, however, elevated ACSL-5 expression increased mitochondrial superoxide production (+30%), which was associated with a significant reduction (p < 0.05) in insulin-stimulated p-Akt and p-AS160 protein levels. We concluded that ACSL-5 in human skeletal muscle functions to increase mitochondrial fatty acid oxidation, but contrary to conventional wisdom, is associated with increased free radical production and reduced insulin signaling.


2005 ◽  
Vol 98 (4) ◽  
pp. 1221-1227 ◽  
Author(s):  
D. S. Rubink ◽  
W. W. Winder

AMP-activated protein kinase (AMPK) has previously been demonstrated to phosphorylate and inactivate skeletal muscle acetyl-CoA carboxylase (ACC), the enzyme responsible for synthesis of malonyl-CoA, an inhibitor of carnitine palmitoyltransferase 1 and fatty acid oxidation. Contraction-induced activation of AMPK with subsequent phosphorylation/inactivation of ACC has been postulated to be responsible in part for the increase in fatty acid oxidation that occurs in muscle during exercise. These studies were designed to answer the question: Does phosphorylation of ACC by AMPK make palmitoyl-CoA a more effective inhibitor of ACC? Purified rat muscle ACC was subjected to phosphorylation by AMPK. Activity was determined on nonphosphorylated and phosphorylated ACC preparations at acetyl-CoA concentrations ranging from 2 to 500 μM and at palmitoyl-CoA concentrations ranging from 0 to 100 μM. Phosphorylation resulted in a significant decline in the substrate saturation curve at all palmitoyl-CoA concentrations. The inhibitor constant for palmitoyl-CoA inhibition of ACC was reduced from 1.7 ± 0.25 to 0.85 ± 0.13 μM as a consequence of phosphorylation. At 0.5 mM citrate, ACC activity was reduced to 13% of control values in response to the combination of phosphorylation and 10 μM palmitoyl-CoA. Skeletal muscle ACC is more potently inhibited by palmitoyl-CoA after having been phosphorylated by AMPK. This may contribute to low-muscle malonyl-CoA values and increasing fatty acid oxidation rates during long-term exercise when plasma fatty acid concentrations are elevated.


2021 ◽  
Vol 11 ◽  
Author(s):  
Ermelinda Ceco ◽  
Diego Celli ◽  
Samuel Weinberg ◽  
Masahiko Shigemura ◽  
Lynn C. Welch ◽  
...  

Muscle dysfunction often occurs in patients with chronic obstructive pulmonary diseases (COPD) and affects ventilatory and non-ventilatory skeletal muscles. We have previously reported that hypercapnia (elevated CO2 levels) causes muscle atrophy through the activation of the AMPKα2-FoxO3a-MuRF1 pathway. In the present study, we investigated the effect of normoxic hypercapnia on skeletal muscle regeneration. We found that mouse C2C12 myoblasts exposed to elevated CO2 levels had decreased fusion index compared to myoblasts exposed to normal CO2. Metabolic analyses of C2C12 myoblasts exposed to high CO2 showed increased oxidative phosphorylation due to increased fatty acid oxidation. We utilized the cardiotoxin-induced muscle injury model in mice exposed to normoxia and 10% CO2 for 21 days and observed that muscle regeneration was delayed. High CO2-delayed differentiation in both mouse C2C12 myoblasts and skeletal muscle after injury and was restored to control levels when cells or mice were treated with a carnitine palmitoyltransfearse-1 (CPT1) inhibitor. Taken together, our data suggest that hypercapnia leads to changes in the metabolic activity of skeletal muscle cells, which results in impaired muscle regeneration and recovery after injury.


Mitochondrion ◽  
2007 ◽  
Vol 7 (6) ◽  
pp. 422-423
Author(s):  
George Kypriotakis ◽  
Bruce H. Cohen ◽  
Sumit Parikh ◽  
Douglas S. Kerr ◽  
Charles L. Hoppel ◽  
...  

2018 ◽  
Vol 46 (1) ◽  
pp. 187-202 ◽  
Author(s):  
Jaume Amengual ◽  
Francisco J. García-Carrizo ◽  
Andrea Arreguín ◽  
Hana Mušinović ◽  
Nuria Granados ◽  
...  

Background/Aims: All-trans retinoic acid (ATRA) has protective effects against obesity and metabolic syndrome. We here aimed to gain further insight into the interaction of ATRA with skeletal muscle metabolism and secretory activity as important players in metabolic health. Methods: Cultured murine C2C12 myocytes were used to study direct effects of ATRA on cellular fatty acid oxidation (FAO) rate (using radioactively-labelled palmitate), glucose uptake (using radioactively-labelled 2-deoxy-D-glucose), triacylglycerol levels (by an enzymatic method), and the expression of genes related to FAO and glucose utilization (by RT-real time PCR). We also studied selected myokine production (using ELISA and immunohistochemistry) in ATRA-treated myocytes and intact mice. Results: Exposure of C2C12 myocytes to ATRA led to increased fatty acid consumption and decreased cellular triacylglycerol levels without affecting glucose uptake, and induced the expression of the myokine irisin at the mRNA and secreted protein level in a dose-response manner. ATRA stimulatory effects on FAO-related genes and the Fndc5 gene (encoding irisin) were reproduced by agonists of peroxisome proliferator-activated receptor β/δ and retinoid X receptors, but not of retinoic acid receptors, and were partially blocked by an AMP-dependent protein kinase inhibitor. Circulating irisin levels were increased by 5-fold in ATRA-treated mice, linked to increased Fndc5 transcription in liver and adipose tissues, rather than skeletal muscle. Immunohistochemistry analysis of FNDC5 suggested that ATRA treatment enhances the release of FNDC5/irisin from skeletal muscle and the liver and its accumulation in interscapular brown and inguinal white adipose depots. Conclusion: These results provide new mechanistic insights on how ATRA globally stimulates FAO and enhances irisin secretion, thereby contributing to leaning effects and improved metabolic status.


Neonatology ◽  
1983 ◽  
Vol 43 (3-4) ◽  
pp. 191-197 ◽  
Author(s):  
James E. Carroll ◽  
Jack B. Shumate ◽  
Aida Villadiego ◽  
Rati M. Choksi ◽  
Daniel P. Morse

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