Induced Pulmonary Arterial Smooth Muscle Cell Proliferation Research Articles

NAMPT mediates PDGF-induced pulmonary arterial smooth muscle cell proliferation by TLR4/NF-κB/PLK4 signaling pathway

Nicotinamide phosphoribosyltransferase (NAMPT), a pleiotropic protein, promotes the proliferation and migration of pulmonary artery smooth muscle cells (PASMCs), which is associated with the genesis and progression of pulmonary arterial hypertension (PAH). NAMPT is highly increased in PAH patient's plasma and highly relevant to PAH severity. The mRNA and protein levels of NAMPT are elevated in PAH animal models. However, the underlying molecular mechanisms how NAMPT mediated platelet-derived growth factor (PDGF)-induced PASMCs proliferation are still unclear. The present study aimed to address these issues. Primary cultured PASMCs were attained from male Sprague-Dawley (SD) rats. Western blotting, RT-PCR, ELISA, cell transfection, Cell Counting Kit-8 (CCK-8) and EdU incorporation assays were used in the experiments. We showed that PDGF upregulated NAMPT expression through the activation of signal transducers and activators of transcription 5 (STAT5), and elevated extracellular NAMPT further promoted the activation of NF-κB through Toll-like receptor 4 (TLR4), which ultimately upregulated polo-like kinase 4 (PLK4) expression leading to PASMCs proliferation. Knockdown of STAT5, NAMPT or PLK4, and inhibition of TLR4 or NF-κB suppressed PDGF-induced PASMCs proliferation. Our study suggests that NAMPT plays an essential role in PDGF-induced PASMCs proliferation via TLR4/NF-κB/PLK4 pathway, suggesting that targeting NAMPT might be valuable in ameliorating pulmonary arterial hypertension.

Alpha1B-adreneroceptor is involved in norepinephrine-induced pulmonary artery smooth muscle cell proliferation via p38 signaling

The higher norepinephrine (NE) concentration induced by sympathetic nerve hyperactivation participated in pulmonary artery smooth muscle cells (PASMCs) over-proliferation and led to pulmonary vascular remodeling (PVR), which played an important role in pulmonary artery hypertension (PAH). However, the underlying mechanism by which NE induced PASMCs proliferation had not been fully elucidated. In the present study, we found that prazosin, the inhibitor of α1-AR, reversed hypoxia-induced changes in pulmonary circulatory function which were analyzed by echocardiography to measure pulmonary artery acceleration time (PAT) and pulmonary arterial velocity time integral (PAVTI) and right heart catheterization to test right ventricular systolic pressure (RVSP), respectively. Western blotting analysis showed that the expression of alpha1B-adreneroceptor (α1B-AR) increased under hypoxic conditions both in vivo and in vitro. Antagonism of α1B-AR by chloroethylclonidine dihydrochloride (CEC) reversed the NE-induced proliferation in rat PASMCs, which was confirmed by applying Western blotting to test proliferating cell nuclear antigen (PCNA) expression, CCK8 assay to test cell viability, scratch-wounding cellular migration assay to show cell proliferative capacity and immunofluorescence to show Ki67 expression. Furthermore, we revealed that antagonism of α1B-AR alleviated NE-induced acceleration of cell-cycle progression by Western blotting to detect cell-cycle-related protein. In addition, Western blotting results showed that antagonism of α1B-AR reversed NE-promoted phosphorylation of p38 (p-p38) under hypoxia. SB202190, an inhibitor of p38, reversed NE-induced proliferation and acceleration of cell-cycle progression of PASMCs. These results suggested that α1B-AR was involved in NE-induced PASMCs proliferation via p38 signaling pathway, which might be downstream of α1B-AR.

The m6A methyltransferase METTL3 promotes hypoxic pulmonary arterial hypertension via targeting PTEN

Abstract Background N6-methyladenosine (m6A) is the most prevalent internal RNA modification in mammal mRNAs. Accumulating evidence has indicated the crucial role of m6A modification in cardiovascular diseases including cardiac hypertrophy, heart failure, ischemic heart disease, vascular calcification, restenosis, and aortic aneurysm. However, the role of m6A methylation in the occurrence and development of hypoxic pulmonary hypertension (HPH) remains largely unknown. Purpose The present study aims to explore the role of key transferase METTL3, in the development of HPH. Methods Hypoxic rat models and pulmonary artery smooth muscle cells (PASMCs) and were used to research the METTL3-mediated m6A in HPH in vivo and in vitro. CCK-8, EdU, PCNA, transwell and TUNEL assay were performed to evaluate the proliferation, migration and apoptosis rates of PASMCs. m6A RNA Methylation Quantification Kit and m6A-qPCR were utilized to measure the total m6A level and m6A-PTEN mRNA expression. RNA immunoprecipitation and RNA pull down were used to detect the interaction between METTL3 and PTEN mRNA. The half-life of mRNA was detected through actinomycin D assay. Results Both METTL3 mRNA and protein were found abnormally upregulated in pulmonary arteries of HPH rats and hypoxia induced PASMCs. Furthermore, downregulation of METTL3 attenuated PASMCs proliferation and migration exposed to hypoxia. In addition, m6A binding protein YTHDF2 was found significantly increased in HPH group in vivo and in vitro. Mechanistically, YTHDF2 recognized METTL3 mediated m6A-PTEN mRNA and promoted the degradation of PTEN. Decreased PTEN led to over-proliferation of PASMCs through activation of PI3K/Akt signaling pathway. Conclusion METTL3/YTHDF2/PTEN axis exerts a significant role in hypoxia induced PASMCs proliferation, providing a novel therapeutic target for HPH. Funding Acknowledgement Type of funding sources: Foundation. Main funding source(s): National Natural Science Foundation of China Figure 1

MicroRNA-663 prevents monocrotaline-induced pulmonary arterial hypertension by targeting TGF-β1/smad2/3 signaling

ObjectivePulmonary vascular remodeling due to excessive growth factor production and pulmonary artery smooth muscle cells (PASMCs) proliferation is the hallmark feature of pulmonary arterial hypertension (PAH). Recent studies suggest that miR-663 is a potent modulator for tumorigenesis and atherosclerosis. However, whether miR-663 involves in pulmonary vascular remodeling is still unclear. Methods and resultsBy using quantitative RT-PCR, we found that miR-663 was highly expressed in normal human PASMCs. In contrast, circulating level of miR-663 dramatically reduced in PAH patients. In addition, in situ hybridization showed that expression of miR-663 was decreased in pulmonary vasculature of PAH patients. Furthermore, MTT and cell scratch-wound assay showed that transfection of miR-663 mimics significantly inhibited platelet derived growth factor (PDGF)-induced PASMCs proliferation and migration, while knockdown of miR-663 expression enhanced these effects. Mechanistically, dual-luciferase reporter assay revealed that miR-663 directly targets the 3’UTR of TGF-β1. Moreover, western blots and ELISA results showed that miR-663 decreased PDGF-induced TGF-β1 expression and secretion, which in turn suppressed the downstream smad2/3 phosphorylation and collagen I expression. Finally, intratracheal instillation of adeno-miR-663 efficiently inhibited the development of pulmonary vascular remodeling and right ventricular hypertrophy in monocrotaline (MCT)-induced PAH rat models. ConclusionThese results indicate that miR-663 is a potential biomarker for PAH. MiR-663 decreases PDGF-BB-induced PASMCs proliferation and prevents pulmonary vascular remodeling and right ventricular hypertrophy in MCT-PAH by targeting TGF-β1/smad2/3 signaling. These findings suggest that miR-663 may represent as an attractive approach for the diagnosis and treatment for PAH.

Abstract 12535: MicroRNA-663 Ameliorates Monocrotaline-induced Pulmonary Arterial Hypertension by Targeting TGFβ1/smad2/3 Signaling

Objective: Pulmonary vascular remodeling due to excessive growth factor production and pulmonary artery smooth muscle cells (PASMCs) proliferation is the hallmark feature of pulmonary arterial hypertension (PAH). Recent studies suggest that miR-663 is a potent modulator for tumorigenesis and atherosclerosis. However, whether miR-663 involves in pulmonary vascular remodeling is still unclear. Methods and Results: By using quantitative RT-PCR, we found that miR-663 was highly expressed in normal human PASMCs. In contrast, circulating level of miR-663 dramatically reduced in PAH patients. In addition, in situ hybridization showed that expression of miR-663 was decreased in PAMSCs of PAH patients. Furthermore, MTT and cell scratch-wound assay showed that transfection of miR-663 mimics significantly inhibited platelet derived growth factor (PDGF)-induced PASMC proliferation and migration, while knockdown of miR-663 expression enhanced these effects. Mechanistically, dual-luciferase reporter assay revealed that miR-663 directly targets the 3’UTR of TGF-β1. Moreover, western blots and ELISA results showed that miR-663 decreased PDGF-induced TGF-β1 expression and secretion, which in turn suppressed the downstream smad2/3 phosphorylation and collagen I expression. Finally, intratracheal instillation of adeno-miR-663 dramatically attenuated pulmonary vascular remodeling and right ventricular hypertrophy, as well as right ventricular systolic pressure and mean pulmonary arterial pressure in MCT-induced PAH rat models. Conclusion: These results indicate that miR-663 is a potential biomarker for PAH. MiR-663 decreases PDGF-BB-induced PAMSCs proliferation and ameliorates pulmonary vascular remodeling and right ventricular hypertrophy in MCT-PAH by targeting TGF-β1/smad2/3 signaling. These findings suggest that miR-663 may represent as an attractive approach for the diagnosis and treatment of PAH.

The six-transmembrane protein Stamp2 ameliorates pulmonary vascular remodeling and pulmonary hypertension in mice

Six-transmembrane protein of prostate (Stamp2) protects from diabetes and atherosclerosis in mice via anti-inflammatory mechanisms. As chronic inflammation is a hallmark of pulmonary arterial hypertension (PAH), we investigated the role of Stamp2. Stamp2 expression was substantially reduced in the lung of humans with idiopathic PAH, as well as in experimental PAH. In Stamp2-deficient mice, hypoxia modestly aggravated pulmonary vascular remodeling and right ventricular pressure compared to WT. As endothelial cell (EC) and pulmonary arterial smooth muscle cell (PASMC) phenotypes drive remodeling in PAH, we explored the role of Stamp2. Knock-down of Stamp2 in human EC neither affected apoptosis, viability, nor release of IL-6. Moreover, Stamp2 deficiency in primary PASMC did not alter mitogenic or migratory properties. As Stamp2 deficiency augmented expression of inflammatory cytokines and numbers of CD68-positive cells in the lung, actions of Stamp2 in macrophages may drive vascular remodeling. Thus, PASMC responses were assessed following treatment with conditioned media of primary Stamp2−/− or WT macrophages. Stamp2−/− supernatants induced PASMC proliferation and migration stronger compared to WT. A cytokine array revealed CXCL12, MCP-1 and IL-6 as most relevant candidates. Experiments with neutralizing antibodies confirmed the role of these cytokines in driving Stamp2’s responses. In conclusion, Stamp2 deficiency aggravates pulmonary vascular remodeling via cross-talk between macrophages and PASMC. Despite a substantial pro-inflammatory response, the hemodynamic effect of Stamp2 deficiency is modest suggesting that additional mechanisms apart from inflammation are necessary to induce severe PAH.

CD248 as a novel therapeutic target in pulmonary arterial hypertension.

Pulmonary vascular remodeling is the most important pathological characteristic of pulmonary arterial hypertension (PAH). No effective treatment for PAH is currently available because the mechanism underlying vascular remodeling is not completely clear. CD248, also known as endosialin, is a transmembrane protein that is highly expressed in pericytes and fibroblasts. Here, we evaluated the role of CD248 in pulmonary vascular remodeling and the processes of PAH pathogenesis. Activation of CD248 in pulmonary artery smooth muscle cells (PASMCs) was found to be proportional to the severity of PAH. CD248 contributed to platelet‐derived growth factor‐BB (PDGF‐BB)‐induced PASMC proliferation and migration along with the shift to more synthetic phenotypes. In contrast, treatment with Cd248 siRNA or the anti‐CD248 therapeutic antibody (ontuxizumab) significantly inhibited the PDGF signaling pathway, obstructed NF‐κB p65‐mediated transcription of Nox4, and decreased reactive oxygen species production induced by PDGF‐BB in PAMSCs. In addition, knockdown of CD248 alleviated pulmonary vascular remodeling in rat PAH models. This study provides novel insights into the dysfunction of PASMCs leading to pulmonary vascular remodeling, and provides evidence for anti‐remodeling treatment for PAH via the immediate targeting of CD248.

EIF2α promotes vascular remodeling via autophagy in monocrotaline-induced pulmonary arterial hypertension rats.

PurposeEukaryotic initiation factor 2α (eIF2α) plays important roles in the proliferation and survival of pulmonary artery smooth muscle cells (PASMCs) in animal hypoxia-induced pulmonary hypertension models. However, the underlying mechanism remains unknown at large. Autophagy has been reported to play a key role in the vascular remodeling in pulmonary arterial hypertension (PAH). The purposes of this study are to determine the functions of eIF2α and autophagy in the vascular remodeling of the monocrotaline-induced PAH rats and to clarify the correlation between eIF2α and autophagy.MethodsWe established a rat model of monocrotaline-induced PAH, and we established a cell model of platelet derived growth factor (PDGF)-induced PASMCs proliferation. The vascular morphology and the expression of eIF2α, LC3B, and p62 were assessed in the pulmonary arterial tissue of Sprague-Dawleyrats and PDGF-induced PASMCs.ResultsAutophagy was significantly active in monocrotaline model group (MCT)-induced PAH rats, which obviously promotes vascular remodeling in MCT-induced PAH rats. Furthermore, the proliferation of PASMCs was induced by PDGF in vitro. The expression of LC3B, eIF2α was increased in the PDGF-induced PASMCs proliferation, and the expression of p62 was reduced in the PDGF-induced PASMCs proliferation. Moreover, eIF2α siRNA downregulated the expression of eIF2α and LC3B, and upregulated the expression of p62 in PDGF-induced PASMCs proliferation. eIF2α siRNA inhibited the PDGF-induced PASMCs proliferation. Finally, chloroquine can upregulate the protein expression of LC3B and p62, it also can inhibit proliferation in PDGF-induced PASMCs.ConclusionBased on these observations, we conclude that eIF2α promotes the proliferation of PASMCs and vascular remodeling in monocrotaline-induced PAH rats through accelerating autophagy pathway.

Activation of PPARγ inhibits HDAC1-mediated pulmonary arterial smooth muscle cell proliferation and its potential mechanisms

The downstream targets of histone deacetylase 1 (HDAC1) mediation of platelet-derived growth factor (PDGF)-induced pulmonary arterial smooth muscle cell (PASMC) proliferation are still unclear, and it is also unknown whether activation of peroxisome proliferator-activated receptor γ (PPARγ) modulates HDAC1 and its down-stream targets in PASMCs. The present study aims to address these issues. Our results showed that PDGF dose- and time-dependently induced PASMC proliferation, and this was accompanied by an increase of HDAC1 and cyclin-dependent kinase 4 (CDK4) protein expression as well as a reduction of microRNA-124 (miR-124). Pre-silencing of HDAC1 with small interfering RNA (siRNA) abolished PDGF-induced miR-124 down-regulation, CDK4 protein up-regulation, and PASMC proliferation. In addition, over-expression of miR-124 reversed CDK4 protein elevation and PASMC proliferation caused by PDGF. We further found that pre-incubation of PASMCs with pioglitazone, an agonist of PPARγ receptors, significantly increased PPARγ expression and activity, and blocked PDGF-stimulated cell proliferation by regulating HDAC1-mediated miR-124 and CDK4 expression. Our study indicates that HDAC1/miR-124/CDK4 axis plays an important role in PDGF-induced PASMC proliferation, and activation of PPARγ inhibits PASMC proliferation by acting on HDAC1 pathway.

Peroxisome proliferator-activated receptor γ attenuates serotonin-induced pulmonary artery smooth muscle cell proliferation and apoptosis inhibition involving ERK1/2 pathway

Serotonin (5-HT) has been shown to be involved in pulmonary vascular remodeling in pulmonary arterial hypertension (PAH) by inducing pulmonary artery smooth muscle cells (PASMCs) proliferation and inhibiting PASMC apoptosis. Peroxisome proliferator-activated receptor γ (PPARγ) plays a crucial role in regulating proliferation and apoptosis of many cell types. Moreover, recently, loss of PPARγ has also been reported to be associated with the development of PAH. The present study is aimed to assess whether PPARγ is involved in 5-HT induced PASMC proliferation and apoptosis inhibition and the possible mechanism. We found that 5-HT could induce PASMC proliferation and inhibit PASMC apoptosis in a dose-dependent manner. Furthermore, we found that 5-HT negatively regulated PPARγ expression and gene promoter activity in PASMCs and 5-HT induced PASMC proliferation and apoptosis resistance could be abolished by PPARγ agonists and enhanced by PPARγ inhibitor. In addition, we found that extracellular signal-regulated kinase (ERK) signaling pathway mediated the 5-HT-induced inhibition of PPARγ expression. Our results might provide novel insights into the mechanisms for the pro-remodeling action of 5-HT in pulmonary vasculature.

Inhibition of SOC/Ca2+/NFAT pathway is involved in the anti-proliferative effect of sildenafil on pulmonary artery smooth muscle cells

BackgroundSildenafil, a potent phosphodiesterase type 5 (PDE5) inhibitor, has been proposed as a treatment for pulmonary arterial hypertension (PAH). The mechanism of its anti-proliferative effect on pulmonary artery smooth muscle cells (PASMC) is unclear. Nuclear translocation of nuclear factor of activated T-cells (NFAT) is thought to be involved in PASMC proliferation and PAH. Increase in cytosolic free [Ca2+] ([Ca2+]i) is a prerequisite for NFAT nuclear translocation. Elevated [Ca2+]i in PASMC of PAH patients has been demonstrated through up-regulation of store-operated Ca2+ channels (SOC) which is encoded by the transient receptor potential (TRP) channel protein. Thus we investigated if: 1) up-regulation of TRPC1 channel expression which induces enhancement of SOC-mediated Ca2+ influx and increase in [Ca2+]i is involved in hypoxia-induced PASMC proliferation; 2) hypoxia-induced promotion of [Ca2+]i leads to nuclear translocation of NFAT and regulates PASMC proliferation and TRPC1 expression; 3) the anti-proliferative effect of sildenafil is mediated by inhibition of this SOC/Ca2+/NFAT pathway.MethodsHuman PASMC were cultured under hypoxia (3% O2) with or without sildenafil treatment for 72 h. Cell number and cell viability were determined with a hemocytometer and MTT assay respectively. [Ca2+]i was measured with a dynamic digital Ca2+ imaging system by loading PASMC with fura 2-AM. TRPC1 mRNA and protein level were detected by RT-PCR and Western blotting respectively. Nuclear translocation of NFAT was determined by immunofluoresence microscopy.ResultsHypoxia induced PASMC proliferation with increases in basal [Ca2+]i and Ca2+ entry via SOC (SOCE). These were accompanied by up-regulation of TRPC1 gene and protein expression in PASMC. NFAT nuclear translocation was significantly enhanced by hypoxia, which was dependent on SOCE and sensitive to SOC inhibitor SKF96365 (SKF), as well as cGMP analogue, 8-brom-cGMP. Hypoxia-induced PASMC proliferation and TRPC1 up-regulation were inhibited by SKF and NFAT blocker (VIVIT and Cyclosporin A). Sildenafil treatment ameliorated hypoxia-induced PASMC proliferation and attenuated hypoxia-induced enhancement of basal [Ca2+]i, SOCE, up-regulation of TRPC1 expression, and NFAT nuclear translocation.ConclusionThe SOC/Ca2+/NFAT pathway is, at least in part, a downstream mediator for the anti-proliferative effect of sildenafil, and may have therapeutic potential for PAH treatment.

Role of Na+/H+ Exchange (NHE) in hypoxia‐induced pulmonary arterial smooth muscle cell (PASMC) growth and migration

In many lung diseases, chronic hypoxia (CH) causes pulmonary hypertension resulting in part from vascular remodeling due to growth/migration of PASMCs. The mechanisms involved in this process are unresolved, but a role for NHE activity has been suggested. We examined whether NHE activity was required for hypoxia‐induced PASMC growth/migration. Equal numbers of PASMCs from rats exposed to normoxia or CH (10% O2; 3 wk) were plated into 96 well plates (proliferation) or onto transwell filters (migration). In some experiments, cells were exposed to hypoxia (4 or 1% O2) ex vivo. PASMCs were cultured with or without the NHE inhibitor, ethyl isopropyl amiloride (EIPA; 10‐5 M). For proliferation, cells were cultured for 48 hr before addition of BrdU for 24 hrs. ELISA for BrdU incorporation showed that CH and ex vivo hypoxia induced PASMC proliferation. EIPA reduced both basal and hypoxia‐induced growth. For migration, PASMCs were cultured on filters for 24 hr, fixed and Coomasie stained. Cells on the transparent filters were imaged (total), the upper side of the filter scraped and images of migrated cells (bottom of filter) obtained. The percent of migrated cells was greater in cells exposed to CH and hypoxia ex vivo. EIPA reduced migration induced by CH and 4% O2. These data suggest that NHE activity modulates hypoxia‐induced PASMC growth and migration and may contribute to increased muscularization of small pulmonary arteries.

Sildenafil Inhibits Human Pulmonary Artery Smooth Muscle Cell Proliferation by Decreasing Capacitative Ca2+ Entry

Ca2+ is a pivotal signal in human pulmonary artery smooth muscle cells (PASMCs) proliferation. Capacitative Ca2+ entry (CCE) via the store-operated channel (SOC), which encoded by the transient receptor potential (TRP) gene, is an important mechanism for regulating intracellular Ca2+ concentration ([Ca2+]i) in PASMCs. Sildenafil, a potent type 5 nucleotide-dependent phosphodiesterase (PDE) inhibitor, has been proposed as a therapeutic tool to treat or prevent pulmonary arterial hypertension (PAH); however, the mechanism of its antiproliferative effect on PASMCs remains unclear. This study was designed to investigate the possible antiproliferative mechanism of sildenafil on human PASMCs, namely, its effect on the Ca2+-signal pathway. Cultured normal PASMCs were treated with endothelin-1 (ET-1) or ET-1 plus sildenafil separately. Cell number and viability were determined with a hemocytometer or MTT assay. [Ca2+]i was measured by loading PASMCs with fura 2-AM. Expression of the TRPC1 gene and protein was detected by RT-PCR and Western blot, respectively. The results show that sildenafil dose-dependently inhibited the proliferation of PASMCs, the enhancement of basal [Ca2+]i level, increase of CCE, and upregulation of TRPC expression induced by ET-1. These results suggest that sildenafil potently inhibits ET-1–induced PASMCs proliferation and downregulation of CCE and TRPC expression may be responsible for its antiproliferative effect.