Histone demethylase JARID1B regulates proliferation and migration of pulmonary arterial smooth muscle cells in mice with chronic hypoxia-induced pulmonary hypertension via nuclear factor-kappa B (NFkB).

Chronic hypoxia-induced pulmonary hypertension (PH) is a disorder that is characterized by increased pulmonary arterial pressure resulting from lung diseases or shortage of oxygen in the body. Excess proliferation of pulmonary vascular cells such as pulmonary artery endothelial cells (PAECs) and pulmonary artery smooth muscle cells (PASMCs) plays a critical role in the pathogenesis of PH. Recent evidence indicates that, in addition to genetic predisposition and environmental factors, epigenetic mechanisms play a pivotal role in etiology of PH. In this study, we investigated the possible role played by jumonji AT-rich interactive domain 1B (JARID1B), a histone demethylase, in regulating the proliferation of vascular smooth muscle cells in chronic hypoxia-induced PH condition. Quantitative polymerase chain reaction analysis of samples from rats with PH showed an elevated expression of JARID1B in their PASMCs, positively correlating with increased nuclear factor-kappa B (NFkB) expression. Further functional studies in vitro indicated that overexpression of JARID1B increased the proliferation and migration of PASMCs, which were inhibited by depletion of NFkB. Genomewide transcriptional analysis revealed that the JARID1B regulated NFkB signaling pathway by directly binding to its promoter. We have also shown that JARID1B indirectly regulates the expression of vascular endothelial growth factor via NFkB signaling and hence may also play a crucial role in controlling PAECs, leading to changes in vascular architecture in PH. Our findings could lead to further studies on the role of JARID1B in PH etiology and therefore could lead to a potential therapeutic target for chronic hypoxia induced pulmonary hypertension.

Li Y ，Liu S ，Zhang Y ，Gao Q ，Sun W ，Fu L ，Cao J ... -  《-》

Vascular peroxidase 1 mediates hypoxia-induced pulmonary artery smooth muscle cell proliferation, apoptosis resistance and migration.

Reactive oxygen species (ROS) play essential roles in the pulmonary vascular remodelling associated with hypoxia-induced pulmonary hypertension (PH). Vascular peroxidase 1 (VPO1) is a newly identified haeme-containing peroxidase that accelerates oxidative stress development in the vasculature. This study aimed to determine the potential role of VPO1 in hypoxia-induced PH-related vascular remodelling. The vascular morphology and VPO1 expression were assessed in the pulmonary arteries of Sprague-Dawley (SD) rats. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 4 (NOX4) and VPO1 expression and HOCl production were significantly increased in hypoxic rats, which also exhibited obvious vascular remodelling. Furthermore, a hypoxia-induced PH model was generated by exposing primary rat pulmonary artery smooth muscle cells (PASMCs) to hypoxic conditions (3% O2, 48 h), which significantly increased the expression of NOX4 and VPO1 and the production of HOCl. These hypoxic changes were accompanied by enhanced proliferation, apoptosis resistance, and migration. In PASMCs, hypoxia-induced changes, including effects on the expression of cell cycle regulators (cyclin B1 and cyclin D1), apoptosis-related proteins (bax, bcl-2, and cleaved caspase-3), migration promoters (matrix metalloproteinases 2 and 9), and NF-κB expression, as well as the production of HOCl, were all inhibited by silencing VPO1 with small interfering RNAs. Moreover, treatment with HOCl under hypoxic conditions upregulated NF-κB expression and enhanced proliferation, apoptosis resistance, and migration in PASMCs, whereas BAY 11-7082 (an inhibitor of NF-κB) significantly inhibited these effects. Collectively, these results demonstrate that VPO1 promotes hypoxia-induced proliferation, apoptosis resistance, and migration in PASMCs via the NOX4/VPO1/HOCl/NF-κB signalling pathway.

You B ，Liu Y ，Chen J ，Huang X ，Peng H ，Liu Z ，Tang Y ，Zhang K ，Xu Q ，Li X ，Cheng G ，Shi R ，Zhang G ... -  《-》

Role of Rho kinase and Na+/H+ exchange in hypoxia-induced pulmonary arterial smooth muscle cell proliferation and migration.

Abnormal proliferation and migration of pulmonary arterial smooth muscle cells (PASMCs) are hallmark characteristics of vascular remodeling in pulmonary hypertension induced by chronic hypoxia. In this study, we investigated the role of the Na(+)/H(+)exchanger (NHE) and alterations in intracellularpH(pHi) homeostasis in meditating increased proliferation and migration inPASMCs isolated from resistance-sized pulmonary arteries from chronically hypoxic rats or from normoxic rats that were exposed to hypoxia ex vivo (1% or 4% O2, 24-96 h). We found thatPASMCs exposed to either in vivo or ex vivo hypoxia exhibited greater proliferative and migratory capacity, elevated pHi, and enhancedNHEactivity. TheNHEinhibitor, ethyl isopropyl amiloride (EIPA), normalized pHiin hypoxicPASMCs and reduced migration by 73% and 45% in cells exposed to in vivo and in vitro hypoxia, respectively. Similarly,EIPAreduced proliferation by 97% and 78% in cells exposed to in vivo and in vitro hypoxia, respectively. We previously demonstrated thatNHEisoform 1 (NHE1) is the predominant isoform expressed inPASMCs. The development of hypoxia-induced pulmonary hypertension and alterations inPASMC pHihomeostasis were prevented in mice deficient forNHE1. We found that short-term (24 h) ex vivo hypoxic exposure did not alter the expression ofNHE1, so we tested the role of Rho kinase (ROCK) as a possible means of increasingNHEactivity. In the presence of theROCKinhibitor, Y-27632, we found that pHiandNHEactivity were normalized and migration and proliferation were reduced inPASMCs exposed to either in vivo (by 68% for migration and 22% for proliferation) or ex vivo (by 43% for migration and 17% for proliferation) hypoxia. From these results, we conclude that during hypoxia, activation ofROCKenhancesNHEactivity and promotesPASMCmigration and proliferation.

Walker J ，Undem C ，Yun X ，Lade J ，Jiang H ，Shimoda LA ... -  《Physiological Reports》

Stox1 induced the proliferation and cell cycle arrest in pulmonary artery smooth muscle cells via AKT signaling pathway.

Pulmonary arterial hypertension (PAH) is a life-threatening disease characterized by the vascular remodeling that also involves proliferation and migration of pulmonary artery smooth muscle cells (PASMCs). Overexpression of Storkhead box (STOX1) regulates genes involved hypoxia, redox balance, nitric oxide, and energy metabolism. In this study, we supposed Stox1 adjusted cells proliferation and migration in PASMCs development and played an important role in the pulmonary arterial vascular remodeling. Hemodynamic assay and Right ventricular morphometric assay were used to check the rat model of PAH. HE staining was used to examine the arterial wall thickness. Masson staining showed that the deposition of collagen was significantly increased in PAH. In addition, Stox1 were assessed by immunofluorescence and immunohistochemistry staining. The effect of Stox1 on PASMCs was assessed by cell counting Kit-8 assay (CCK-8 assay), Scratch-Wound assay, EdU staining assay, Cell cycle analysis and Western blot. Right ventricular systolic pressure (RVSP) and right ventricular were significantly increased in hypoxia group and monocrotaline group compared to control group. The expression of Stox1 was increased in lung tissues in PAH rats. In vitro, the expression of Stox1 was up-regulated with time-dependent manner in hypoxia condition. Meanwhile, Stxo1 promoted the proliferation and migration in hypoxia-treated PASMCs. Moreover, we found that hypoxia promoted the expression of PCNA, Cyclin E and Cyclin A, increased more cells from G0/G1 phase to S phase and induced the activation of AKT proteins, which was significantly attenuated by inhibition of Stox1 expression in PASMCs. These findings indicated that Stox1 induced proliferation of PASMCs and the effect is, at least in part, mediated through AKT signaling pathway.

Xu Y ，Sun Z ，Wang Q ，Wang T ，Liu Y ，Yu F ... -  《-》

Phosphatidylinositol 3-Kinase-DNA Methyltransferase 1-miR-1281-Histone Deacetylase 4 Regulatory Axis Mediates Platelet-Derived Growth Factor-Induced Proliferation and Migration of Pulmonary Artery Smooth Muscle Cells.

Platelet-derived growth factor BB, a potent mitogen of pulmonary artery smooth muscle cells (PASMCs), has been implicated in pulmonary arterial remodeling, which is a key pathogenic feature of pulmonary arterial hypertension. Previous microRNA profiling in platelet-derived growth factor BB-treated PASMCs found a significantly downregulated microRNA, miR-1281, but it has not been associated with any cellular function, and we investigated the possibility. Real-time quantitative reverse transcription-polymerase chain reaction assay proved that downregulation of miR-1281 was a conserved phenomenon in human and rat PASMCs. Overexpression and inhibition of miR-1281 in PASMCs promoted and suppressed, respectively, the cell proliferation and migration. Bioinformatic prediction and 3'-untranslated region reporter assay identified histone deacetylase 4 to be a direct target of miR-1281. Supporting this, proliferation and migration assay demonstrated the cellular function of histone deacetylase 4 is inversely correlated with that of miR-1281. Mechanistically, it is found that platelet-derived growth factor BB activates the phosphatidylinositol 3-kinase pathway, which then induces the expression of DNA methyltransferase 1, leading to enhanced methylation of a flanking CpG island and repressed miR-1281 expression. Finally, a reduced miR-1281 level was consistently identified in hypoxic PASMCs in vitro, in pulmonary arteries of rats with monocrotaline-induced pulmonary arterial hypertension, and in serum of patients with coronary heart disease-pulmonary arterial hypertension. These data suggest that there may be a diagnostic and therapeutic use for miR-1281. Herein, we report a novel regulatory axis, phosphatidylinositol 3-kinase-DNA methyltransferase 1-miR-1281-histone deacetylase 4, integrating multiple epigenetic regulators that participate in platelet-derived growth factor BB-stimulated PASMC proliferation and migration and pulmonary vascular remodeling.

Li Y ，Li L ，Qian Z ，Lin B ，Chen J ，Luo Y ，Qu J ，Raj JU ，Gou D ... -  《Journal of the American Heart Association》