RESUMO
PPARgamma, a nuclear transcription factor, is expressed in various cells within the vasculature and in cardiomyocytes. It has been suggested that PPARgamma is involved in atherogenesis and in cardiac hypertrophy. Therefore, we sought to quantify PPARgamma mRNA in coronary arteries, the aorta and left ventricular specimens from patients with ischaemic (CHD) and dilated cardiomyopathy (CMP). Using real-time PCR, we were able to demonstrate the expression of PPARgamma in all of the human specimens. The lowest expression of PPARgamma was detected in the aorta specimens of both groups (this was set to one). In comparison, the expression in coronary arteries was 2.32-fold in CHD- and 3.78-fold in CMP specimens and in the left ventricle specimens, 2.12-fold in CHD- and 3.51-fold in CMP. Samples from CHD patients showed a higher expression of PPARgamma in all of the samples compared to those from CMP patients (aorta: 1.99-fold; coronary arteries: 1.35; left ventricles: 1.23). PPARgamma levels were not significantly correlated to CD 36 expression values in any group, suggesting that higher levels of PPARgamma are not principally due to increased PPARgamma expression in macrophages. This was confirmed by immunohistochemical analysis, which showed that PPARgamma is also located in the smooth muscle layer and in cardiomyocytes. In conclusion, our observations of increased PPAR mRNA expression in the coronary arteries and left ventricles from CHD and CMP patients suggest an important function of this nuclear receptor in the pathogenesis of heart disease.
Assuntos
Cardiomiopatia Dilatada/metabolismo , Isquemia Miocárdica/metabolismo , Receptores Citoplasmáticos e Nucleares/análise , Fatores de Transcrição/análise , Adulto , Idoso , Aorta/metabolismo , Antígenos CD36/metabolismo , Cardiomiopatia Dilatada/etiologia , Vasos Coronários/metabolismo , Proteínas de Ligação a DNA/análise , Proteínas de Ligação a DNA/genética , Humanos , Imuno-Histoquímica , Masculino , Pessoa de Meia-Idade , Isquemia Miocárdica/etiologia , Miocárdio/metabolismo , Reação em Cadeia da Polimerase , RNA Mensageiro/metabolismo , Receptores Citoplasmáticos e Nucleares/genética , Fatores de Transcrição/genéticaRESUMO
Peroxisome proliferator-activated receptor gamma (PPARgamma) is a ligand activated transcription factor which regulates gene expression in various tissues. PPARgamma was primarily found to be associated with lipid and glucose metabolism. Recent experimental studies provided evidence that PPARgamma is also expressed in the arterial wall and in cardiomyocytes and described PPARgamma as a transducer of antihypertropic signaling in the heart. This comparative study sought to investigate whether PPARgamma is differently expressed in the aorta, coronary arteries and left ventricle specimens derived from healthy heart donors (n = 5). By using quantitative PCR, we found that PPARgamma is expressed in all of the human specimens with the by far highest expression (5.01-fold) in the left ventricles compared to aorta, whereas no significant difference was detected between coronary arteries (0.93-fold) vs. aorta. Furthermore, especially great interindividual variations were observed in PPARgamma expression in aorta, and to a lesser extent, in coronary arteries and left ventricle specimens. In conclusion, our data argue for the prominent role of PPARgamma in the human heart, particularly in the normal left ventricle.
Assuntos
Miocárdio/metabolismo , Receptores Citoplasmáticos e Nucleares/metabolismo , Fatores de Transcrição/metabolismo , Adulto , Análise de Variância , Aorta/metabolismo , Vasos Coronários/metabolismo , Feminino , Ventrículos do Coração/metabolismo , Humanos , Masculino , Especificidade de Órgãos , Reação em Cadeia da Polimerase , RNA Mensageiro/metabolismo , Receptores Citoplasmáticos e Nucleares/genética , Fatores de Transcrição/genéticaRESUMO
Endothelial nitric oxide synthase (eNOS), VEGF, and hypoxia-inducible factor 1-alpha (HIF-1alpha) are important regulators of endothelial function, which plays a role in the pathophysiology of heart failure (HF). PGE1 analog treatment in patients with HF elicits beneficial hemodynamic effects, but the precise mechanisms have not been investigated. We have investigated the effects of the PGE1 analog alprostadil on eNOS, VEGF, and HIF-1alpha expression in human umbilical vein endothelial cells (HUVEC) using RT-PCR and immunoblotting under normoxic and hypoxic conditions. In addition, we studied protein expression by immunohistochemical staining in explanted hearts from patients with end-stage HF, treated or untreated with systemic alprostadil. Alprostadil causes an upregulation of eNOS and VEGF protein and mRNA expression in HUVEC and decreases HIF-1alpha. Hypoxia potently increased eNOS, VEGF, and HIF-1alpha synthesis. The alprostadil-induced upregulation of eNOS and VEGF was prevented by inhibition of MAPKs with PD-98056 or U-0126. Consistently, the expression of eNOS and VEGF was increased, and HIF-1alpha was reduced in failing hearts treated with alprostadil. The potent effects of alprostadil on endothelial VEGF and eNOS synthesis may be useful for patients with HF where endothelial dysfunction is involved in the disease process.
Assuntos
Alprostadil/análogos & derivados , Alprostadil/farmacologia , Células Endoteliais/metabolismo , Fator A de Crescimento do Endotélio Vascular/biossíntese , Vasodilatadores/farmacologia , Western Blotting , Capilares/efeitos dos fármacos , Capilares/enzimologia , Capilares/metabolismo , Cardiomiopatia Dilatada/enzimologia , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/enzimologia , Inibidores Enzimáticos/farmacologia , Feminino , Humanos , Subunidade alfa do Fator 1 Induzível por Hipóxia/biossíntese , Imuno-Histoquímica , Técnicas In Vitro , Proteínas Quinases Ativadas por Mitógeno/antagonistas & inibidores , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Gravidez , RNA Mensageiro/biossíntese , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Cordão Umbilical/citologia , Cordão Umbilical/efeitos dos fármacos , Cordão Umbilical/enzimologiaRESUMO
We showed that the melatonin receptor subtype, MT1, is expressed in healthy and diseased human coronary arteries. As studies in experimental animals suggest that the MT2 melatonin receptor subtype is also present in the vasculature, we investigated whether the MT2 is expressed in human aorta and coronary arteries. Additionally, MT2 expression in human ventricular specimens was analysed, as melatonin was shown to affect myocyte function. Expression of the MT2-receptor was studied in sections of isolated coronary arteries, aorta and left ventricular specimens from healthy heart donors (control) and patients with dilated or ischemic cardiomyopathy. MT2 expression was found by reverse transcriptase (RT)-nested-polymerase chain reaction (PCR) in all of the specimens (aorta, left ventricle and coronary arteries) derived from controls. Also, visible evidence for receptor expression was found in 12 of 15 samples from cardiomyopathy patients and 10 of 15 of coronary heart disease patients. Additionally, the expression of MT2-receptor between aorta, left ventricle and coronary arteries varied among the individuals, some of them showing highest expression in the aorta while in others principal expression sites were coronary arteries or left ventricles. In conclusion, the MT2-receptor subtype is present in human arteries and left ventricles and it is suggested that in coronary heart disease MT2-receptor expression is altered. Furthermore, there is evidence for heterogeneous MT2 expression patterns in individual patients.