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Transgenic overexpression of GTP cyclohydrolase 1 in cardiomyocytes ameliorates post-infarction cardiac remodeling.

ABSTRACT: GTP cyclohydrolase 1 (GCH1) and its product tetrahydrobiopterin play crucial roles in cardiovascular health and disease, yet the exact regulation and role of GCH1 in adverse cardiac remodeling after myocardial infarction are still enigmatic. Here we report that cardiac GCH1 is degraded in remodeled hearts after myocardial infarction, concomitant with increases in the thickness of interventricular septum, interstitial fibrosis, and phosphorylated p38 mitogen-activated protein kinase and decreases in left ventricular anterior wall thickness, cardiac contractility, tetrahydrobiopterin, the dimers of nitric oxide synthase, sarcoplasmic reticulum Ca2+ release, and the expression of sarcoplasmic reticulum Ca2+ handling proteins. Intriguingly, transgenic overexpression of GCH1 in cardiomyocytes reduces the thickness of interventricular septum and interstitial fibrosis and increases anterior wall thickness and cardiac contractility after infarction. Moreover, we show that GCH1 overexpression decreases phosphorylated p38 mitogen-activated protein kinase and elevates tetrahydrobiopterin levels, the dimerization and phosphorylation of neuronal nitric oxide synthase, sarcoplasmic reticulum Ca2+ release, and sarcoplasmic reticulum Ca2+ handling proteins in post-infarction remodeled hearts. Our results indicate that the pivotal role of GCH1 overexpression in post-infarction cardiac remodeling is attributable to preservation of neuronal nitric oxide synthase and sarcoplasmic reticulum Ca2+ handling proteins, and identify a new therapeutic target for cardiac remodeling after infarction.

SUBMITTER: Liu Y

PROVIDER: S-EPMC5465102 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature

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Transgenic overexpression of GTP cyclohydrolase 1 in cardiomyocytes ameliorates post-infarction cardiac remodeling.

Liu Yanan Y Baumgardt Shelley L SL Fang Juan J Shi Yang Y Qiao Shigang S Bosnjak Zeljko J ZJ Vásquez-Vivar Jeannette J Xia Zhengyuan Z Warltier David C DC Kersten Judy R JR Ge Zhi-Dong ZD

Scientific reports 20170608 1

GTP cyclohydrolase 1 (GCH1) and its product tetrahydrobiopterin play crucial roles in cardiovascular health and disease, yet the exact regulation and role of GCH1 in adverse cardiac remodeling after myocardial infarction are still enigmatic. Here we report that cardiac GCH1 is degraded in remodeled hearts after myocardial infarction, concomitant with increases in the thickness of interventricular septum, interstitial fibrosis, and phosphorylated p38 mitogen-activated protein kinase and decreases ...[more]

PMID: 28596578

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Project description:Ubiquitin carboxyl-terminal hydrolase L1 (UCHL1) is a deubiquitinase known to play essential roles in the nervous tissue. Myocardial upregulation of UCHL1 was observed in human dilated cardiomyopathy and several animal models of heart disease, but the (patho)physiological significance of UCHL1 in cardiomyocytes remains undefined. Hence, we conducted this study to fill this critical gap. We produced cardiomyocyte-restricted Uchl1 knockout (CKO) by coupling the Uchl1-floxed allele with transgenic Myh6-Cre in C57B/6J inbred mice. Mice transgenic for Myh6-Cre were used as controls (CTL). Myocardial Uchl1 proteins were markedly reduced in CKO mice but they did not display discernible abnormal phenotype. Ten-week old CTL or CKO mice were subjected to left anterior descending artery ligation (myocardial infarction, MI) or sham surgery (Sham) and characterized at 7- and 28-day after surgery. Compared with Sham mice, significant increases in myocardial UCHL1 proteins were detected in CTL MI but not in CKO MI mice. MI-induced left ventricular (LV) chamber dilation, reduction of ejection fraction (EF) and fractional shortening (FS), and LV anterior wall thinning detected by echocardiography were comparable between the CTL MI and CKO MI groups 7-day post-MI. However, by 28-day post-MI, MI-induced LV chamber dilatation, EF and FS reduction, increases of myocardial ubiquitin conjugates, and increases in the heart weight to body weight ratio and the ventricular weight to body weight ratio were significantly more pronounced in CKO MI than CTL MI mice. As further revealed by LV pressure-volume relationship analyses, CKO MI mice but not CTL MI mice displayed significant decreases in stroke volume, cardiac output, and the maximum rates of LV pressure rising or declining and of LV volume declining, as well as significant increases in LV end-diastolic pressure and Tau, compared with their respective Sham controls. LC3-II flux assays reveal that autophagic flux is decreased in CKO mouse myocardium as well as in cultured Uchl1-deficient cardiomyocytes. In conclusion, UCHL1 of cardiomyocytes is dispensable for development but promotes macroautophagy in cardiomyocytes. Upregulation of UCHL1 in post-MI hearts occurs primarily in the cardiomyocytes and protects against post-MI cardiac remodeling and malfunction likely through supporting autophagic flux and proteostasis during a stress condition.

Project description:Supplemental Digital Content is available in the text. Abnormal uteroplacental remodeling leads to placental hypoperfusion, causing fetal growth restriction and pregnancy-related hypertension, which are associated with endothelial dysfunction and markers of reduced vascular NO bioavailability and oxidative stress. Tetrahydrobiopterin (BH4) is a redox cofactor for eNOS (endothelial NO synthase) with a required role in NO generation. Using mice models and human samples, we investigated the physiological requirement for endothelial cell BH4 in uteroplacental vascular adaptation and blood pressure regulation to pregnancy. In pregnant mice, selective maternal endothelial BH4 deficiency resulting from targeted deletion of Gch1 caused progressive hypertension during pregnancy and fetal growth restriction. Maternal endothelial cell Gch1 deletion caused defective functional and structural remodeling in uterine arteries and in spiral arteries, leading to placental insufficiency. Using primary endothelial cells isolated from either normal or hypertensive pregnancies, we found that hypertensive pregnancies are associated with reduced endothelial cell BH4 levels, impaired eNOS activity, and reduced endothelial cell proliferation, mediated by reduced GTPCH (GTP cyclohydrolase 1) protein. In rescue experiments, high blood pressure and fetal growth restriction in pregnant endothelial cell Gch1 deficient mice was not rescued by oral BH4 supplementation, due to systemic oxidation of BH4 to dihydrobiopterin. However, the fully reduced folate, 5-methyltetrahydrofolate prevented BH4 oxidation, reduced blood pressure to normal levels, and normalized fetal growth. We identify a critical requirement for maternal endothelial cell BH4 biosynthesis in uteroplacental vascular remodeling in pregnancy. Restoration of endothelial cell BH4 with reduced folates identifies a novel therapeutic target for the prevention and treatment of pregnancy-related hypertension such as preeclampsia.

Dataset Information

Transgenic overexpression of GTP cyclohydrolase 1 in cardiomyocytes ameliorates post-infarction cardiac remodeling.

Publications

Transgenic overexpression of GTP cyclohydrolase 1 in cardiomyocytes ameliorates post-infarction cardiac remodeling.

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