RESUMEN
BACKGROUND: Recent studies have shown that plasma levels of the biologically inactive prohormone for brain natriuretic peptide (proBNP) are increased in patients with heart failure. This can contribute to a reduction in the effectiveness of circulating BNP and exacerbate heart failure progression. The precise mechanisms governing the increase in proBNP remain unclear, however. METHODS AND RESULTS: We used our recently developed, highly sensitive human proBNP assay system to investigate the mechanisms underlying the increase in plasma proBNP levels. We divided 53 consecutive patients hospitalized with heart failure into 2 groups based on their aortic plasma levels of immunoreactive BNP. Patients with higher levels exhibited more severe heart failure, a higher proportion of proBNP among the immunoreactive BNP forms secreted from failing hearts, and a weaker effect of BNP as estimated from the ratio of plasma cyclic guanosine monophosphate levels to log-transformed plasma BNP levels. Glycosylation at threonines 48 and 71 of human proBNP contributed to the increased secretion of proBNP by attenuating its processing, and GalNAc-transferase (GALNT) 1 and 2 mediated the glycosylation-regulated increase in cardiac human proBNP secretion. Cardiac GALNT1 and 2 expression was suppressed by microRNA (miR)-30, which is abundantly expressed in the myocardium of healthy hearts, but is suppressed in failing hearts. CONCLUSIONS: We have elucidated a novel miR-30-GALNT1/2 axis whose dysregulation increases the proportion of inactive proBNP secreted by the heart and impairs the compensatory actions of BNP during the progression of heart failure.
Asunto(s)
Aorta Torácica/metabolismo , Regulación de la Expresión Génica , Insuficiencia Cardíaca/genética , MicroARNs/genética , Miocardio/metabolismo , N-Acetilgalactosaminiltransferasas/genética , Péptido Natriurético Encefálico/sangre , Fragmentos de Péptidos/sangre , Anciano , Animales , Animales Recién Nacidos , Biomarcadores/sangre , Western Blotting , Células Cultivadas , Cromatografía en Gel , Modelos Animales de Enfermedad , Progresión de la Enfermedad , Ecocardiografía , Femenino , Estudios de Seguimiento , Glicosilación , Insuficiencia Cardíaca/diagnóstico , Insuficiencia Cardíaca/metabolismo , Ventrículos Cardíacos/diagnóstico por imagen , Ventrículos Cardíacos/metabolismo , Ventrículos Cardíacos/fisiopatología , Humanos , Masculino , MicroARNs/biosíntesis , Persona de Mediana Edad , Miocardio/patología , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/patología , N-Acetilgalactosaminiltransferasas/biosíntesis , Precursores de Proteínas , Ratas , Ratas Endogámicas Dahl , Reacción en Cadena en Tiempo Real de la Polimerasa , Estudios Retrospectivos , Transducción de Señal , Polipéptido N-AcetilgalactosaminiltransferasaRESUMEN
AIMS: The overloaded heart remodels by cardiomyocyte hypertrophy and interstitial fibrosis, which contributes to the development of heart failure. Signalling via the TGFß-pathway is crucial for this remodelling. Here we tested the hypothesis that microRNAs in the overloaded heart regulate this remodelling process via inhibition of the TGFß-pathway. METHODS AND RESULTS: We show that the miRNA-15 family, which we found to be up-regulated in the overloaded heart in multiple species, inhibits the TGFß-pathway by targeting of TGFBR1 and several other genes within this pathway directly or indirectly, including p38, SMAD3, SMAD7, and endoglin. Inhibition of miR-15b by subcutaneous injections of LNA-based antimiRs in C57BL/6 mice subjected to transverse aorta constriction aggravated fibrosis and to a lesser extent also hypertrophy. CONCLUSION: We identified the miR-15 family as a novel regulator of cardiac hypertrophy and fibrosis acting by inhibition of the TGFß-pathway.
Asunto(s)
Cardiomegalia/metabolismo , Cardiomiopatías/metabolismo , MicroARNs/metabolismo , Miocitos Cardíacos/metabolismo , Transducción de Señal , Factor de Crecimiento Transformador beta/metabolismo , Remodelación Ventricular , Regiones no Traducidas 3' , Animales , Células COS , Cardiomegalia/genética , Cardiomegalia/patología , Cardiomegalia/fisiopatología , Cardiomiopatías/genética , Cardiomiopatías/patología , Cardiomiopatías/fisiopatología , Estudios de Casos y Controles , Chlorocebus aethiops , Modelos Animales de Enfermedad , Fibrosis , Células Hep G2 , Humanos , Ratones Endogámicos C57BL , MicroARNs/genética , Proteínas Serina-Treonina Quinasas/genética , Proteínas Serina-Treonina Quinasas/metabolismo , Ratas Transgénicas , Receptor Tipo I de Factor de Crecimiento Transformador beta , Receptores de Factores de Crecimiento Transformadores beta/genética , Receptores de Factores de Crecimiento Transformadores beta/metabolismo , Proteína smad3/genética , Proteína smad3/metabolismo , Proteína smad7/genética , Proteína smad7/metabolismo , Transfección , Regulación hacia Arriba , Proteínas Quinasas p38 Activadas por Mitógenos/genética , Proteínas Quinasas p38 Activadas por Mitógenos/metabolismoRESUMEN
The Kruppel-like factor (KLF) family of transcription factors regulates diverse cell biological processes including proliferation, differentiation, survival and growth. Previous studies have shown that KLF15 inhibits cardiac hypertrophy by repressing the activity of pivotal cardiac transcription factors such as GATA4, MEF2 and myocardin. We set out this study to characterize the interaction of KLF15 with putative other transcription factors. We first show that KLF15 interacts with myocardin-related transcription factors (MRTFs) and strongly represses the transcriptional activity of MRTF-A and MRTF-B. Second, we identified a region within the C-terminal zinc fingers of KLF15 that contains the nuclear localization signal. Third, we investigated whether overexpression of KLF15 in the heart would have therapeutic potential. Using recombinant adeno-associated viruses (rAAV) we have overexpressed KLF15 specifically in the mouse heart and provide the first evidence that elevation of cardiac KLF15 levels prevents the development of cardiac hypertrophy in a model of Angiotensin II induced hypertrophy.