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A PKM2 signature in the failing heart.

ABSTRACT: A salient feature of the failing heart is metabolic remodeling towards predominant glucose metabolism and activation of the fetal gene program. Sunitinib is a multitargeted receptor tyrosine kinase inhibitor used for the treatment of highly vascularized tumors. In diabetic patients, sunitinib significantly decreases blood glucose. However, a considerable proportion of sunitinib-treated patients develop cardiac dysfunction or failure. We asked whether sunitinib treatment results in shift towards glycolysis in the heart. Glucose uptake by the heart was increased fivefold in mice treated with sunitinib. Transcript analysis by qPCR revealed an induction of genes associated with glycolysis and reactivation of the fetal gene program. Additionally, we observed a shift in the enzyme pyruvate kinase from the adult M1 (PKM1) isoform to the fetal M2 (PKM2) isoform, a hallmark of the Warburg Effect. This novel observation led us to examine whether a similar shift occurs in human heart failure. Examination of tissue from patients with heart failure similarly displayed an induction of PKM2. Moreover, this phenomenon was partially reversed following mechanical unloading. We propose that pyruvate kinase isoform switching represents a novel feature of the fetal gene program in the failing heart.

SUBMITTER: Rees ML

PROVIDER: S-EPMC4380635 | biostudies-literature | 2015 Apr

REPOSITORIES: biostudies-literature

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A PKM2 signature in the failing heart.

Rees Meredith L ML Subramaniam Janani J Li Yuanteng Y Hamilton Dale J DJ Frazier O Howard OH Taegtmeyer Heinrich H

Biochemical and biophysical research communications 20150228 3

A salient feature of the failing heart is metabolic remodeling towards predominant glucose metabolism and activation of the fetal gene program. Sunitinib is a multitargeted receptor tyrosine kinase inhibitor used for the treatment of highly vascularized tumors. In diabetic patients, sunitinib significantly decreases blood glucose. However, a considerable proportion of sunitinib-treated patients develop cardiac dysfunction or failure. We asked whether sunitinib treatment results in shift towards ...[more]

PMID: 25735978

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Project description:BackgroundThe failing heart is traditionally described as metabolically inflexible and oxygen starved, causing energetic deficit and contractile dysfunction. Current metabolic modulator therapies aim to increase glucose oxidation to increase oxygen efficiency of adenosine triphosphate production, with mixed results.MethodsTo investigate metabolic flexibility and oxygen delivery in the failing heart, 20 patients with nonischemic heart failure with reduced ejection fraction (left ventricular ejection fraction 34.9±9.1) underwent separate infusions of insulin+glucose infusion (I+G) or Intralipid infusion. We used cardiovascular magnetic resonance to assess cardiac function and measured energetics using phosphorus-31 magnetic resonance spectroscopy. To investigate the effects of these infusions on cardiac substrate use, function, and myocardial oxygen uptake (MVo2), invasive arteriovenous sampling and pressure-volume loops were performed (n=9).ResultsAt rest, we found that the heart had considerable metabolic flexibility. During I+G, cardiac glucose uptake and oxidation were predominant (70±14% total energy substrate for adenosine triphosphate production versus 17±16% for Intralipid; P=0.002); however, no change in cardiac function was seen relative to basal conditions. In contrast, during Intralipid infusion, cardiac long-chain fatty acid (LCFA) delivery, uptake, LCFA acylcarnitine production, and fatty acid oxidation were all increased (LCFA 73±17% of total substrate versus 19±26% total during I+G; P=0.009). Myocardial energetics were better with Intralipid compared with I+G (phosphocreatine/adenosine triphosphate 1.86±0.25 versus 2.01±0.33; P=0.02), and systolic and diastolic function were improved (LVEF 34.9±9.1 baseline, 33.7±8.2 I+G, 39.9±9.3 Intralipid; P<0.001). During increased cardiac workload, LCFA uptake and oxidation were again increased during both infusions. There was no evidence of systolic dysfunction or lactate efflux at 65% maximal heart rate, suggesting that a metabolic switch to fat did not cause clinically meaningful ischemic metabolism.ConclusionsOur findings show that even in nonischemic heart failure with reduced ejection fraction with severely impaired systolic function, significant cardiac metabolic flexibility is retained, including the ability to alter substrate use to match both arterial supply and changes in workload. Increasing LCFA uptake and oxidation is associated with improved myocardial energetics and contractility. Together, these findings challenge aspects of the rationale underlying existing metabolic therapies for heart failure and suggest that strategies promoting fatty acid oxidation may form the basis for future therapies.

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A PKM2 signature in the failing heart.

Publications

A PKM2 signature in the failing heart.

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