Cardiomyocytes rely on metabolic substrates, not only to fuel cardiac output, but also for growth and remodelling during stress. Here we show that mitochondrial pyruvate carrier (MPC) abundance mediates pathological cardiac hypertrophy. MPC abundance was reduced in failing hypertrophic human hearts, as well as in the myocardium of mice induced to fail by angiotensin II or through transverse aortic constriction. Constitutive knockout of cardiomyocyte MPC1/2 in mice resulted in cardiac hypertrophy and reduced survival, while tamoxifen-induced cardiomyocyte-specific reduction of MPC1/2 to the attenuated levels observed during pressure overload was sufficient to induce hypertrophy with impaired cardiac function. Failing hearts from cardiomyocyte-restricted knockout mice displayed increased abundance of anabolic metabolites, including amino acids and pentose phosphate pathway intermediates and reducing cofactors. These hearts showed a concomitant decrease in carbon flux into mitochondrial tricarboxylic acid cycle intermediates, as corroborated by complementary 1,2-[ 13 C 2 ]glucose tracer studies. In contrast, inducible cardiomyocyte overexpression of MPC1/2 resulted in increased tricarboxylic acid cycle intermediates, and sustained carrier expression during transverse aortic constriction protected against cardiac hypertrophy and failure. Collectively, our findings demonstrate that loss of the MPC1/2 causally mediates adverse cardiac remodelling.Healthy myocardial mitochondria primarily utilize oxidative phosphorylation to generate adenosine triphosphate (ATP), which is required to meet the heart's energy-demanding function as a blood pump. In healthy myocardium with sufficient oxygen supply, oxidation of fatty acids provides approximately 60-90% of the myocardial acetyl-coenzyme A that contributes to ATP generation, with 10-40% arising from pyruvate oxidation 1,2 . However, the stressed human heart changes its fuel preference 3,4 , switching from fatty acids to glucose as a favoured carbon source 5,6 . Consistent with this observation, several studies with animal models of pressure overload-induced hypertrophy have shown reduced fatty acid oxidation rates with enhanced glucose uptake and glycolysis, accompanied by a compensatory anaplerosis to maintain the tricarboxylic acid cycle flux in the pathological heart [7][8][9] . Interestingly, this enhanced glycolysis and carbon influx via anaplerosis did not augment ATP production, consistent with an 'uncoupling' between glycolysis and glucose oxidation during pathological hypertrophy 7,10,11 . Furthermore, instead of pyruvate predominantly being oxidized in the mitochondria, it is metabolized by alternative pathways, including reductive fermentation to lactate, despite sufficient oxygen availability 12,13 . This is reminiscent of the Warburg effect, whereby many cancer cells increase glucose uptake and convert it to lactate via the reduction of pyruvate despite oxygen availability.Since the identification of the mitochondrial pyruvate carrier (MPC) in 2012 (refs. 14,15 ...

Soluble epoxide hydrolase (sEH) is inhibited by electrophilic lipids by their adduction to Cys521 proximal to its catalytic center. This inhibition prevents hydrolysis of the enzymes' epoxyeicosatrienoic acid (EET) substrates, so they accumulate inducing vasodilation to lower blood pressure (BP). We generated a Cys521Ser sEH redoxdead knockin (KI) mouse model that was resistant to this mode of inhibition. The electrophilic lipid 10-nitro-oleic acid (NO 2 -OA) inhibited hydrolase activity and also lowered BP in an angiotensin II-induced hypertension model in wild-type (WT) but not KI mice. Furthermore, EET/dihydroxy-epoxyeicosatrienoic acid isomer ratios were elevated in plasma from WT but not KI mice following NO 2 -OA treatment, consistent with the redox-dead mutant being resistant to inhibition by lipid electrophiles. sEH was inhibited in WT mice fed linoleic acid and nitrite, key constituents of the Mediterranean diet that elevates electrophilic nitro fatty acid levels, whereas KIs were unaffected. These observations reveal that lipid electrophiles such as NO 2 -OA mediate antihypertensive signaling actions by inhibiting sEH and suggest a mechanism accounting for protection from hypertension afforded by the Mediterranean diet.thiol | cardiovascular

Despite the mechanisms for endogenous nitroxyl (HNO) production and action being incompletely understood, pharmacological donors show broad therapeutic promise and are in clinical trials. Mass spectrometry and site-directed mutagenesis showed that chemically distinct HNO donors 1-nitrosocyclohexyl acetate or Angeli’s salt induced disulfides within cGMP-dependent protein kinase I-alpha (PKGIα), an interdisulfide between Cys42 of the two identical subunits of the kinase and a previously unobserved intradisulfide between Cys117 and Cys195 in the high affinity cGMP-binding site. Kinase activity was monitored in cells transfected with wildtype (WT), Cys42Ser or Cys117/195Ser PKGIα that cannot form the inter- or intradisulfide, respectively. HNO enhanced WT kinase activity, an effect significantly attenuated in inter- or intradisulfide-deficient PKGIα. To investigate whether the intradisulfide modulates cGMP binding, real-time imaging was performed in vascular smooth muscle cells expressing a FRET-biosensor comprising the cGMP-binding sites of PKGIα. HNO induced FRET changes similar to those elicited by an increase of cGMP, suggesting that intradisulfide formation is associated with activation of PKGIα. Intradisulfide formation in PKGIα correlated with enhanced HNO-mediated vasorelaxation in mesenteric arteries in vitro and arteriolar dilation in vivo in mice. HNO induces intradisulfide formation in PKGIα, inducing the same effect as cGMP binding, namely kinase activation and thus vasorelaxation.