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      Increased Protein Tyrosine Phosphatase 1B (PTP1B) Activity and Cardiac Insulin Resistance Precede Mitochondrial and Contractile Dysfunction in Pressure‐Overloaded Hearts

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          Abstract

          Background

          Insulin resistance in diabetes mellitus has been associated with mitochondrial dysfunction. Defects at the level of mitochondria are also characteristic of heart failure. We assessed changes in cardiac insulin response and mitochondrial function in a model of pressure overload‐induced heart failure.

          Methods and Results

          Rats underwent aortic banding to induce pressure overload. At 10 weeks, rats showed cardiac hypertrophy and pulmonary congestion, but left ventricular dilatation and systolic dysfunction were only evident after 20 weeks. This contractile impairment was accompanied by mitochondrial dysfunction as shown by markedly reduced state 3 respiration of isolated mitochondria. Aortic banding did not affect systemic insulin response. However, insulin‐stimulated cardiac glucose uptake and glucose oxidation were significantly diminished at 10 and 20 weeks, which indicates cardiac insulin resistance starting before the onset of mitochondrial and contractile dysfunction. The impaired cardiac insulin action was related to a decrease in insulin‐stimulated phosphorylation of insulin receptor β. Consistently, we found elevated activity of protein tyrosine phosphatase 1B ( PTP1B) at 10 and 20 weeks, which may blunt insulin action by dephosphorylating insulin receptor β. PTP1B activity was also significantly increased in left ventricular samples of patients with systolic dysfunction undergoing aortic valve replacement because of aortic stenosis.

          Conclusions

          Pressure overload causes cardiac insulin resistance that precedes and accompanies mitochondrial and systolic dysfunction. Activation of PTP1B in the heart is associated with heart failure in both rats and humans and may account for cardiac insulin resistance. PTP1B may be a potential target to modulate insulin sensitivity and contractile function in the failing heart.

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          Most cited references 28

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          The war against heart failure: the Lancet lecture.

          Heart failure is a global problem with an estimated prevalence of 38 million patients worldwide, a number that is increasing with the ageing of the population. It is the most common diagnosis in patients aged 65 years or older admitted to hospital and in high-income nations. Despite some progress, the prognosis of heart failure is worse than that of most cancers. Because of the seriousness of the condition, a declaration of war on five fronts has been proposed for heart failure. Efforts are underway to treat heart failure by enhancing myofilament sensitivity to Ca(2+); transfer of the gene for SERCA2a, the protein that pumps calcium into the sarcoplasmic reticulum of the cardiomyocyte, seems promising in a phase 2 trial. Several other abnormal calcium-handling proteins in the failing heart are candidates for gene therapy; many short, non-coding RNAs--ie, microRNAs (miRNAs)--block gene expression and protein translation. These molecules are crucial to calcium cycling and ventricular hypertrophy. The actions of miRNAs can be blocked by a new class of drugs, antagomirs, some of which have been shown to improve cardiac function in animal models of heart failure; cell therapy, with autologous bone marrow derived mononuclear cells, or autogenous mesenchymal cells, which can be administered as cryopreserved off the shelf products, seem to be promising in both preclinical and early clinical heart failure trials; and long-term ventricular assistance devices are now used increasingly as a destination therapy in patients with advanced heart failure. In selected patients, left ventricular assistance can lead to myocardial recovery and explantation of the device. The approaches to the treatment of heart failure described, when used alone or in combination, could become important weapons in the war against heart failure.
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            Effect of insulin on human skeletal muscle mitochondrial ATP production, protein synthesis, and mRNA transcripts.

            Mitochondria are the primary site of skeletal muscle fuel metabolism and ATP production. Although insulin is a major regulator of fuel metabolism, its effect on mitochondrial ATP production is not known. Here we report increases in vastus lateralis muscle mitochondrial ATP production capacity (32-42%) in healthy humans (P < 0.01) i.v. infused with insulin (1.5 milliunits/kg of fat-free mass per min) while clamping glucose, amino acids, glucagon, and growth hormone. Increased ATP production occurred in association with increased mRNA levels from both mitochondrial (NADH dehydrogenase subunit IV) and nuclear [cytochrome c oxidase (COX) subunit IV] genes (164-180%) encoding mitochondrial proteins (P < 0.05). In addition, muscle mitochondrial protein synthesis, and COX and citrate synthase enzyme activities were increased by insulin (P < 0.05). Further studies demonstrated no effect of low to high insulin levels on muscle mitochondrial ATP production for people with type 2 diabetes mellitus, whereas matched nondiabetic controls increased 16-26% (P < 0.02) when four different substrate combinations were used. In conclusion, insulin stimulates mitochondrial oxidative phosphorylation in skeletal muscle along with synthesis of gene transcripts and mitochondrial protein in human subjects. Skeletal muscle of type 2 diabetic patients has a reduced capacity to increase ATP production with high insulin levels.
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              Reduced activation of phosphatidylinositol-3 kinase and increased serine 636 phosphorylation of insulin receptor substrate-1 in primary culture of skeletal muscle cells from patients with type 2 diabetes.

              To understand better the defects in the proximal steps of insulin signaling during type 2 diabetes, we used differentiated human skeletal muscle cells in primary culture. When compared with cells from control subjects, myotubes established from patients with type 2 diabetes presented the same defects as those previously evidenced in vivo in muscle biopsies, including defective stimulation of phosphatidylinositol (PI) 3-kinase activity, decreased association of PI 3-kinase with insulin receptor substrate (IRS)-1 and reduced IRS-1 tyrosine phosphorylation during insulin stimulation. In contrast to IRS-1, the signaling through IRS-2 was not altered. Investigating the causes of the reduced tyrosine phosphorylation of IRS-1, we found a more than twofold increase in the basal phosphorylation of IRS-1 on serine 636 in myotubes from patients with diabetes. Concomitantly, there was a higher basal mitogen-activated protein kinase (MAPK) activity in these cells, and inhibition of the MAPKs with PD98059 strongly reduced the level of serine 636 phosphorylation. These results suggest that IRS-1 phosphorylation on serine 636 might be involved in the reduced phosphorylation of IRS-1 on tyrosine and in the subsequent alteration of insulin-induced PI 3-kinase activation. Moreover, increased MAPK activity seems to play a role in the phosphorylation of IRS-1 on serine residue in human muscle cells.
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                Author and article information

                Contributors
                doenst@med.uni-jena.de
                Journal
                J Am Heart Assoc
                J Am Heart Assoc
                10.1002/(ISSN)2047-9980
                JAH3
                ahaoa
                Journal of the American Heart Association: Cardiovascular and Cerebrovascular Disease
                John Wiley and Sons Inc. (Hoboken )
                2047-9980
                21 June 2018
                03 July 2018
                : 7
                : 13 ( doiID: 10.1002/jah3.2018.7.issue-13 )
                Affiliations
                [ 1 ] Department of Cardiothoracic Surgery Jena University Hospital Friedrich Schiller University Jena Jena Germany
                [ 2 ] Department of General and Visceral Surgery Klinikum Burgenlandkreis Zeitz Germany
                [ 3 ] IUF‐Leibniz Research Institute for Environmental Medicine Duesseldorf Germany
                [ 4 ] Central Institute of Clinical Chemistry and Laboratory Medicine University of Duesseldorf Germany
                Author notes
                [* ] Correspondence to: Torsten Doenst, MD, Department of Cardiothoracic Surgery, Jena University Hospital, Friedrich Schiller University Jena, Am Klinikum 1, 07747 Jena, Germany. E‐mail: doenst@ 123456med.uni-jena.de
                [†]

                Dr Nguyen and Dr Schwarzer contributed equally to this work.

                Article
                JAH33140
                10.1161/JAHA.118.008865
                6064925
                29929988
                © 2018 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

                This is an open access article under the terms of the http://creativecommons.org/licenses/by-nc-nd/4.0/ License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non‐commercial and no modifications or adaptations are made.

                Page count
                Figures: 6, Tables: 2, Pages: 12, Words: 7093
                Product
                Funding
                Funded by: DFG
                Award ID: SFB1116 TP A04
                Categories
                Original Research
                Original Research
                Heart Failure
                Custom metadata
                2.0
                jah33140
                03 July 2018
                Converter:WILEY_ML3GV2_TO_NLMPMC version:version=5.4.1.1 mode:remove_FC converted:03.07.2018

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