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IGF-1 signaling in neonatal hypoxia-induced pulmonary hypertension: Role of epigenetic regulation.

ABSTRACT: Pulmonary hypertension is a fatal disease characterized by a progressive increase in pulmonary artery pressure accompanied by pulmonary vascular remodeling and increased vasomotor tone. Although some biological pathways have been identified in neonatal hypoxia-induced pulmonary hypertension (PH), little is known regarding the role of growth factors in the pathogenesis of PH in neonates. In this study, using a model of hypoxia-induced PH in neonatal mice, we demonstrate that the growth factor insulin-like growth factor-1 (IGF-1), a potent activator of the AKT signaling pathway, is involved in neonatal PH. After exposure to hypoxia, IGF-1 signaling is activated in pulmonary endothelial and smooth muscle cells in vitro, and the IGF-1 downstream signal pAKT(S473) is upregulated in lungs of neonatal mice. We found that IGF-1 regulates ET-1 expression in pulmonary endothelial cells and that IGF-1 expression is regulated by histone deacetylases (HDACs). In addition, there is a differential cytosine methylation site in the IGF-1 promoter region in response to neonatal hypoxia. Moreover, inhibition of HDACs with apicidin decreases neonatal hypoxia-induced global DNA methylation levels in lungs and specific cytosine methylation levels around the pulmonary IGF-1 promoter region. Finally, HDAC inhibition with apicidin reduces chronic hypoxia-induced activation of IGF-1/pAKT signaling in lungs and attenuates right ventricular hypertrophy and pulmonary vascular remodeling. Taken together, we conclude that IGF-1, which is epigenetically regulated, is involved in the pathogenesis of pulmonary hypertension in neonatal mice. This study implicates a novel HDAC/IGF-1 epigenetic pathway in the regulation of hypoxia-induced PH and warrants further study of the role of IGF-1 in neonatal pulmonary hypertensive disease.

SUBMITTER: Yang Q

PROVIDER: S-EPMC4578983 | biostudies-literature | 2015 Oct

REPOSITORIES: biostudies-literature

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IGF-1 signaling in neonatal hypoxia-induced pulmonary hypertension: Role of epigenetic regulation.

Yang Qiwei Q Sun Miranda M Ramchandran Ramaswamy R Raj J Usha JU

Vascular pharmacology 20150425

Pulmonary hypertension is a fatal disease characterized by a progressive increase in pulmonary artery pressure accompanied by pulmonary vascular remodeling and increased vasomotor tone. Although some biological pathways have been identified in neonatal hypoxia-induced pulmonary hypertension (PH), little is known regarding the role of growth factors in the pathogenesis of PH in neonates. In this study, using a model of hypoxia-induced PH in neonatal mice, we demonstrate that the growth factor ins ...[more]

PMID: 25921925

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Project description:Baicalin, an important flavonoid in Scutellaria baicalensis Georgi extracts, exerts a variety of pharmacological effects. In this study, we explored the effects of baicalin on chronic hypoxia-induced pulmonary arterial hypertension (PAH) and investigated the mechanism underlying these effects. Moreover, we examined whether the inflammatory response was mediated by the A2A receptor (A2AR) and stromal cell-derived factor-1 (SDF-1)/C-X-C chemokine receptor type 4 (CXCR4)-induced phosphatidyl inositol-3-kinase (PI3K) signaling in vivo.We established a hypoxia-induced pulmonary hypertension (HPH) mouse model by subjecting wild-type (WT) and A2AR knockout (A2AR-/-) animals to chronic hypoxia, and we examined the effects of a 4-week treatment with baicalin or the A2AR agonist CGS21680 in these animals. Invasive hemodynamic parameters, the right ventricular hypertrophy index, pulmonary congestion, the pulmonary arterial remodeling index, blood gas parameters, A2AR expression, and the expression of SDF-1/CXCR4/PI3K/protein kinase B (PKB; AKT) signaling components were measured.Compared with WT mice, A2AR-/- mice exhibited increased right ventricular systolic pressure (RVSP), right ventricle-to-left ventricle plus septum [RV/(LV + S)] ratio, RV weight-to-body weight (RV/BW) ratio, and lung wet weight-to-body weight (Lung/BW) ratio in the absence of an altered mean carotid arterial pressure (mCAP). These changes were accompanied by increases in pulmonary artery wall area and thickness and reductions in arterial oxygen pressure (PaO2) and hydrogen ion concentration (pH). In the HPH model, A2AR-/- mice displayed increased CXCR4, SDF-1, phospho-PI3K, and phospho-AKT expression compared with WT mice. Treating WT and A2AR-/- HPH mice with baicalin or CGS21680 attenuated the hypoxia-induced increases in RVSP, RV/(LV + S) and Lung/BW, as well as pulmonary arterial remodeling. Additionally, baicalin or CGS21680 alone could reverse the hypoxia-induced increases in CXCR4, SDF-1, phospho-PI3K, and phospho-AKT expression. Moreover, baicalin improved the hypoxemia induced by 4 weeks of hypoxia. Finally, we found that A2AR levels in WT lung tissue were enhanced by hypoxia and that baicalin up-regulated A2AR expression in WT hypoxic mice.Baicalin exerts protective effects against clinical HPH, which are partly mediated through enhanced A2AR activity and down-regulated SDF-1/CXCR4-induced PI3K/AKT signaling. Therefore, the A2AR may be a promising target for baicalin in treating HPH.

Dataset Information

IGF-1 signaling in neonatal hypoxia-induced pulmonary hypertension: Role of epigenetic regulation.

Publications

IGF-1 signaling in neonatal hypoxia-induced pulmonary hypertension: Role of epigenetic regulation.

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