Deleterious action of FA metabolites on ATP synthesis: possible link between lipotoxicity, mitochondrial dysfunction, and insulin resistance

2008 ◽  
Vol 295 (3) ◽  
pp. E678-E685 ◽  
Author(s):  
Muhammad A. Abdul-Ghani ◽  
Florian L. Muller ◽  
Yuhong Liu ◽  
Alberto O. Chavez ◽  
Bogdan Balas ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Mitochondrial Dysfunction ◽  
Atp Synthesis ◽  
Insulin Resistant ◽  
Palmitoyl Carnitine ◽  
Mitochondrial Inner Membrane ◽  
Transport Chain ◽  
Mitochondrial Defects ◽  
Ffa Metabolism

Insulin resistance is a characteristic feature of type 2 diabetes and obesity. Insulin-resistant individuals manifest multiple disturbances in free fatty acid (FFA) metabolism and have excessive lipid accumulation in insulin target tissues. Although much evidence supports a causal role for altered FFA metabolism in the development of insulin resistance, i.e., “lipotoxicity”, the intracellular mechanisms by which elevated plasma FFA levels cause insulin resistance have yet to be completely elucidated. Recent studies have implicated a possible role for mitochondrial dysfunction in the pathogenesis of insulin resistance in skeletal muscle. We examined the effect of FFA metabolites [palmitoyl carnitine (PC), palmitoyl-coenzyme A (CoA), and oleoyl-CoA] on ATP synthesis in mitochondria isolated from mouse and human skeletal muscle. At concentrations ranging from 0.5 to 2 μM, these FFA metabolites stimulated ATP synthesis; however, above 5 μM, there was a dose-response inhibition of ATP synthesis. Furthermore, 10 μM PC inhibits ATP synthesis from pyruvate. Elevated PC concentrations (≥10 μM) inhibit electron transport chain activity and decrease the mitochondrial inner membrane potential. These acquired mitochondrial defects, caused by a physiological increase in the concentration of FFA metabolites, provide a mechanistic link between lipotoxicity, mitochondrial dysfunction, and muscle insulin resistance.

Abstract 12196: Optic Atrophy 1 Deficiency in Skeletal Muscle Results in Progressive Mitochondrial Dysfunction, but Prevents Age-Induced Obesity and Glucose Intolerance

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Renata Pereira ◽  
Zhonggang Li ◽  
Karen Oliveira ◽  
Karla Pires ◽  
E. Dale Abel
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Body Weight ◽  
Mitochondrial Dysfunction ◽  
Glucose Intolerance ◽  
Optic Atrophy ◽  
Atp Synthesis ◽  
Mitochondrial Fusion ◽  
Elderly Subjects ◽  
Old Mice

Mitochondrial dysfunction develops in skeletal muscle with aging and may contribute to insulin resistance, which increases cardiovascular risk. A link between skeletal muscle insulin resistance and perturbed mitochondrial fusion and fission has been suggested but not proven. Optic Atrophy 1 (OPA1) is an inner mitochondrial membrane protein that plays a fundamental role in mitochondrial fusion, quality control and respiratory function. OPA1 levels are reduced in muscle from elderly subjects; however, the specific roles of OPA1 in the aging muscle have not been studied. We, therefore, generated a mouse model with inducible deletion of the OPA1 gene in skeletal muscle of adult C57Bl6 mice, by crossing OPA1 floxed mice with HSA-Cre (ERT2) mice (KO). Four-week-old KO and wild-type (WT) mice were treated with tamoxifen for 5 days to induce recombination, resulting in a 60% reduction in OPA1 protein levels 8 weeks after treatment (12-wk-old mice). OPA1 deficiency resulted in altered mitochondrial cristae morphology, with preserved maximally stimulated mitochondria respirations in soleus and reduced ATP synthesis rates in KO mice, 8 weeks after recombination (12-wk-old mice). At 20 weeks, mitochondrial respiration and ATP synthesis were decreased in KO mice, concomitantly with increased AMPK and eIF2 alpha activation. Body weight was reduced in 12 and 20-week old KO mice relative to WT. At forty-weeks, body weight was increased by 40% in WT mice vs. 15% in KO mice. This increase in body weight occurred on the basis of increased fat mass (70% in WT vs. 30% in KO). Lean mass was reduced by 30% in WT mice, which was attenuated in KO mice (~10%). Glucose tolerance tests were similar between WT and KO mice at 12 and 20 weeks of age; however, 40-wk-old WT mice had severe glucose intolerance, which was prevented in KO mice. Interestingly, KO mice had a100-fold increase in FGF21 mRNA levels in muscle compared to WT mice. These data reveal that OPA1 is critical for maintaining skeletal muscle mitochondrial function in the adult muscle and suggest that reducing OPA1 levels activates signaling pathways that retard age-induced obesity and glucose intolerance.

scholarly journals Improvement of obesity-linked skeletal muscle insulin resistance by strength and endurance training

2017 ◽  
Vol 234 (3) ◽  
pp. R159-R181 ◽  
Author(s):  
Sergio Di Meo ◽  
Susanna Iossa ◽  
Paola Venditti
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Mitochondrial Dysfunction ◽  
Endurance Training ◽  
Glucose Transport ◽  
Antioxidant Defenses ◽  
Metabolic Dysfunction ◽  
Muscle Insulin Resistance ◽  
Insulin Resistant ◽  
Skeletal Muscle Insulin Resistance

Obesity-linked insulin resistance is mainly due to fatty acid overload in non-adipose tissues, particularly skeletal muscle and liver, where it results in high production of reactive oxygen species and mitochondrial dysfunction. Accumulating evidence indicates that resistance and endurance training alone and in combination can counteract the harmful effects of obesity increasing insulin sensitivity, thus preventing diabetes. This review focuses the mechanisms underlying the exercise role in opposing skeletal muscle insulin resistance-linked metabolic dysfunction. It is apparent that exercise acts through two mechanisms: (1) it stimulates glucose transport by activating an insulin-independent pathway and (2) it protects against mitochondrial dysfunction-induced insulin resistance by increasing muscle antioxidant defenses and mitochondrial biogenesis. However, antioxidant supplementation combined with endurance training increases glucose transport in insulin-resistant skeletal muscle in an additive fashion only when antioxidants that are able to increase the expression of antioxidant enzymes and/or the activity of components of the insulin signaling pathway are used.

scholarly journals Exercise, heat shock proteins and insulin resistance

2017 ◽  
Vol 373 (1738) ◽  
pp. 20160529 ◽  
Author(s):  
Ashley E. Archer ◽  
Alex T. Von Schulze ◽  
Paige C. Geiger
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Heat Shock ◽  
Heat Shock Proteins ◽  
Metabolic Effects ◽  
Diabetic Patients ◽  
Alcoholic Fatty Liver ◽  
Insulin Resistant ◽  
Exercise Induced ◽  
Shock Proteins

Best known as chaperones, heat shock proteins (HSPs) also have roles in cell signalling and regulation of metabolism. Rodent studies demonstrate that heat treatment, transgenic overexpression and pharmacological induction of HSP72 prevent high-fat diet-induced glucose intolerance and skeletal muscle insulin resistance. Overexpression of skeletal muscle HSP72 in mice has been shown to increase endurance running capacity nearly twofold and increase mitochondrial content by 50%. A positive correlation between HSP72 mRNA expression and mitochondrial enzyme activity has been observed in human skeletal muscle, and HSP72 expression is markedly decreased in skeletal muscle of insulin resistant and type 2 diabetic patients. In addition, decreased levels of HSP72 correlate with insulin resistance and non-alcoholic fatty liver disease progression in livers from obese patients. These data suggest the targeted induction of HSPs could be a therapeutic approach for preventing metabolic disease by maintaining the body's natural stress response. Exercise elicits a number of metabolic adaptations and is a powerful tool in the prevention and treatment of insulin resistance. Exercise training is also a stimulus for increased HSP expression. Although the underlying mechanism(s) for exercise-induced HSP expression are currently unknown, the HSP response may be critical for the beneficial metabolic effects of exercise. Exercise-induced extracellular HSP release may also contribute to metabolic homeostasis by actively restoring HSP72 content in insulin resistant tissues containing low endogenous levels of HSPs. This article is part of the theme issue ‘Heat shock proteins as modulators and therapeutic targets of chronic disease: an integrated perspective’.

Hemodynamic actions of insulin

1994 ◽  
Vol 267 (2) ◽  
pp. E187-E202 ◽  
Author(s):  
A. D. Baron
Keyword(s):  
Nitric Oxide ◽  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Glucose Uptake ◽  
Pressor Response ◽  
Physiological Role ◽  
Oxide System ◽  
Maximal Response ◽  
Insulin Resistant ◽  
The Right

There is accumulating evidence that insulin has a physiological role to vasodilate skeletal muscle vasculature in humans. This effect occurs in a dose-dependent fashion within a half-maximal response of approximately 40 microU/ml. This vasodilating action is impaired in states of insulin resistance such as obesity, non-insulin-dependent diabetes, and elevated blood pressure. The precise physiological role of insulin-mediated vasodilation is not known. Data indicate that the degree of skeletal muscle perfusion can be an important determinant of insulin-mediated glucose uptake. Therefore, it is possible that insulin-mediated vasodilation is an integral aspect of insulin's overall action to stimulate glucose uptake; thus defective vasodilation could potentially contribute to insulin resistance. In addition, insulin-mediated vasodilation may play a role in the regulation of vascular tone. Data are provided to indicate that the pressor response to systemic norepinephrine infusions is increased in obese insulin-resistant subjects. Moreover, the normal effect of insulin to shift the norepinephrine pressor dose-response curve to the right is impaired in these patients. Therefore, impaired insulin-mediated vasodilation could further contribute to the increased prevalence of hypertension observed in states of insulin resistance. Finally, data are presented to indicate that, via a yet unknown interaction with the endothelium, insulin is able to increase nitric oxide synthesis and release and through this mechanism vasodilate. It is interesting to speculate that states of insulin resistance might also be associated with a defect in insulin's action to modulate the nitric oxide system.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Hepatokine ERAP1 impairs skeletal muscle insulin sensitivity via ADRB2/PKA pathway

2020 ◽  
Author(s):  
Feifan Guo ◽  
Yuguo Niu ◽  
Haizhou Jiang ◽  
Hanrui Yin ◽  
Fenfen Wang ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Insulin Sensitivity ◽  
Neutralizing Antibodies ◽  
Leptin Receptor ◽  
Whole Body ◽  
C2c12 Myotubes ◽  
Insulin Resistant ◽  
Skeletal Muscle Insulin Sensitivity ◽  
Pka Pathway

Abstract The current study aimed to investigate the role of endoplasmic reticulum aminopeptidase 1 (ERAP1), a novel hepatokine, in whole-body glucose metabolism. Here, we found that hepatic ERAP1 levels were increased in insulin-resistant leptin-receptor-mutated (db/db) and high-fat diet (HFD)-fed mice. Consistently, hepatic ERAP1 overexpression attenuated skeletal muscle (SM) insulin sensitivity, whereas knockdown ameliorated SM insulin resistance. Furthermore, serum and hepatic ERAP1 levels were positively correlated, and recombinant mouse ERAP1 or conditioned medium with high ERAP1 content (CM-ERAP1) attenuated insulin signaling in C2C12 myotubes, and CM-ERAP1 or HFD-induced insulin resistance was blocked by ERAP1 neutralizing antibodies. Mechanistically, ERAP1 reduced ADRB2 expression and interrupted ADRB2-dependent signaling in C2C12 myotubes. Finally, ERAP1 inhibition via global knockout or the inhibitor thimerosal improved insulin sensitivity. Together, ERAP1 is a hepatokine that impairs SM and whole-body insulin sensitivity, and its inhibition might provide a therapeutic strategy for diabetes, particularly for those with SM insulin resistance.

UCP-mediated energy depletion in skeletal muscle increases glucose transport despite lipid accumulation and mitochondrial dysfunction

2004 ◽  
Vol 286 (3) ◽  
pp. E347-E353 ◽  
Author(s):  
Dong-Ho Han ◽  
Lorraine A. Nolte ◽  
Jeong-Sun Ju ◽  
Trey Coleman ◽  
John O. Holloszy ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Mitochondrial Dysfunction ◽  
Glucose Transport ◽  
Lipid Accumulation ◽  
Uncoupling Protein ◽  
Serum Glucose ◽  
Mineral Density ◽  
Beneficial Effects ◽  
High Level

To address the potential role of lipotoxicity and mitochondrial function in insulin resistance, we studied mice with high-level expression of uncoupling protein-1 in skeletal muscle (UCP-H mice). Body weight, body length, and bone mineral density were decreased in UCP-H mice compared with wild-type littermates. Forelimb grip strength and muscle mass were strikingly decreased, whereas muscle triglyceride content was increased fivefold in UCP-H mice. Electron microscopy demonstrated lipid accumulation and large mitochondria with abnormal architecture in UCP-H skeletal muscle. ATP content and key mitochondrial proteins were decreased in UCP-H muscle. Despite mitochondrial dysfunction and increased intramyocellular fat, fasting serum glucose was 22% lower and insulin-stimulated glucose transport 80% higher in UCP-H animals. These beneficial effects on glucose metabolism were associated with increased AMP kinase and hexokinase activities, as well as elevated levels of GLUT4 and myocyte enhancer factor-2 proteins A and D in skeletal muscle. These results suggest that UCP-H mice have a mitochondrial myopathy due to depleted energy stores sufficient to compromise growth and impair muscle function. Enhanced skeletal muscle glucose transport in this setting suggests that excess intramyocellular lipid and mitochondrial dysfunction are not sufficient to cause insulin resistance in mice.

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

2012 ◽  
Vol 302 (6) ◽  
pp. E731-E739 ◽  
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.

Selective in vitro reversal of the insulin resistance of glucose transport in denervated rat skeletal muscle

1989 ◽  
Vol 257 (3) ◽  
pp. E418-E425 ◽  
Author(s):  
M. O. Sowell ◽  
S. L. Dutton ◽  
M. G. Buse
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Insulin Receptor ◽  
Glucose Transport ◽  
Glycogen Synthesis ◽  
Insulin Response ◽  
Medium Composition ◽  
Insulin Resistant ◽  
Denervated Muscles

Denervation (24 h) of skeletal muscle causes severe postreceptor insulin resistance of glucose transport and glycogen synthesis that is demonstrable in isolated muscles after short (30 min) preincubations. After longer preincubations (2-4 h), the insulin response of glucose transport increased to normal, whereas glycogen synthesis remained insulin resistant. Basal and insulin-stimulated amino acid transport were significantly lower in denervated muscles than in controls after short or long incubations, although the percentage stimulation of transport by insulin was not significantly different. The development of glucose transport insulin resistance after denervation was not attributable to increased sensitivity to glucocorticoids or adenosine. The selective in vitro reversal of glucose transport insulin resistance was not dependent on medium composition, did not require protein or prostaglandin synthesis, and could not be attributed to release of a positive regulator into the medium. The data suggest 1) the insulin receptor in muscle stimulates glucose transport by a signaling pathway that is not shared by other insulin-sensitive effector systems, and 2) denervation may affect insulin receptor signal transduction at more than one site.

Mitochondria-associated ER membranes in glucose homeostasis and insulin resistance

2020 ◽  
Vol 319 (6) ◽  
pp. E1053-E1060
Author(s):  
Logan K. Townsend ◽  
Henver S. Brunetta ◽  
Marcelo A. S. Mori
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Endoplasmic Reticulum ◽  
Adipose Tissue ◽  
Er Stress ◽  
Mitochondrial Dysfunction ◽  
Glucose Homeostasis ◽  
Calcium Homeostasis ◽  
Adenine Nucleotides ◽  
Current Controversy

Obesity and insulin resistance (IR) are associated with endoplasmic reticulum (ER) stress and mitochondrial dysfunction in several tissues. Although for many years mitochondrial and ER function were studied separately, these organelles also connect to produce interdependent functions. Communication occurs at mitochondria-associated ER membranes (MAMs) and regulates lipid and calcium homeostasis, apoptosis, and the exchange of adenine nucleotides, among other things. Recent evidence suggests that MAMs contribute to organelle, cellular, and systemic metabolism. In obesity and IR models, metabolic tissues such as the liver, skeletal muscle, pancreas, and adipose tissue present alterations in MAM structure or function. The purpose of this mini review is to highlight the MAM disruptions that occur in each tissue during obesity and IR and its relationship with glucose homeostasis and IR. We also discuss the current controversy that surrounds MAMs’ role in the development of IR.

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