RESUMO
The metabolic rewiring of cardiomyocytes is a widely accepted hallmark of heart failure (HF). These metabolic changes include a decrease in mitochondrial pyruvate oxidation and an increased export of lactate. We identify the mitochondrial pyruvate carrier (MPC) and the cellular lactate exporter monocarboxylate transporter 4 (MCT4) as pivotal nodes in this metabolic axis. We observed that cardiac assist device-induced myocardial recovery in chronic HF patients was coincident with increased myocardial expression of the MPC. Moreover, the genetic ablation of the MPC in cultured cardiomyocytes and in adult murine hearts was sufficient to induce hypertrophy and HF. Conversely, MPC overexpression attenuated drug-induced hypertrophy in a cell-autonomous manner. We also introduced a novel, highly potent MCT4 inhibitor that mitigated hypertrophy in cultured cardiomyocytes and in mice. Together, we find that alteration of the pyruvate-lactate axis is a fundamental and early feature of cardiac hypertrophy and failure.
Assuntos
Proteínas de Transporte de Ânions/metabolismo , Cardiomegalia/patologia , Insuficiência Cardíaca/patologia , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Transportadores de Ácidos Monocarboxílicos/metabolismo , Proteínas Musculares/metabolismo , Animais , Proteínas de Transporte de Ânions/antagonistas & inibidores , Proteínas de Transporte de Ânions/genética , Cardiomegalia/induzido quimicamente , Cardiomegalia/complicações , Insuficiência Cardíaca/etiologia , Coração Auxiliar , Humanos , Ácido Láctico/metabolismo , Potencial da Membrana Mitocondrial , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mitocôndrias/metabolismo , Proteínas de Transporte da Membrana Mitocondrial/antagonistas & inibidores , Proteínas de Transporte da Membrana Mitocondrial/genética , Transportadores de Ácidos Monocarboxílicos/antagonistas & inibidores , Transportadores de Ácidos Monocarboxílicos/genética , Proteínas Musculares/antagonistas & inibidores , Miócitos Cardíacos/citologia , Miócitos Cardíacos/metabolismo , Ácido Pirúvico/metabolismo , Interferência de RNA , RNA Interferente Pequeno/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Função Ventricular Esquerda/fisiologiaRESUMO
Elevated hepatic synthesis of fatty acids and triglycerides, driven by hyperactivation of the SREBP-1c transcription factor, has been implicated as a causal feature of metabolic syndrome. SREBP-1c activation requires the proteolytic maturation of the endoplasmic-reticulum-bound precursor to the active, nuclear transcription factor, which is stimulated by feeding and insulin signaling. Here, we show that feeding and insulin stimulate the hepatic expression of PASK. We also demonstrate, using genetic and pharmacological approaches, that PASK is required for the proteolytic maturation of SREBP-1c in cultured cells and in the mouse and rat liver. Inhibition of PASK improves lipid and glucose metabolism in dietary animal models of obesity and dyslipidemia. Administration of a PASK inhibitor decreases hepatic expression of lipogenic SREBP-1c target genes, decreases serum triglycerides, and partially reverses insulin resistance. While the signaling network that controls SREBP-1c activation is complex, we propose that PASK is an important component with therapeutic potential.