Notch signaling change in pulmonary vascular remodeling in rats with pulmonary hypertension and its implication for therapeutic intervention

Jagged 2 inhibition attenuates hypoxia-induced mitochondrial damage and pulmonary hypertension through Sirtuin 1 signaling

Notch pathway has played a significant role in the pathophysiology of pulmonary hypertension (PH). However, the role of Jagged 2 (Jag2), one ligand of Notch, remains to be elucidated.Therefore, determining the contribution of Jag2 to PH and its impact on pulmonary artery smooth muscle cells (PASMCs) was the aim of this investigation. Adeno-associated virus-mediated Jag2 inhibition was used to explore the role of Jag2 in peripheral pulmonary vascular remodeling assessed in a rat model of chronic hypoxia (10% O2, 4 weeks) induced pulmonary hypertension. In vitro, the effect of Jag2 silencing on hypoxia (1% O2, 24h) induced rat PASMCs was determined. Group differences were assessed using a 2-sided unpaired Student's t-test for two groups and one-way ANOVA for multiple groups. Jag2 upregulation was first confirmed in rats with sustained hypoxia-induced PH using publicly available gene expression data, experimental PH rat models and hypoxia induced rat PASMCs. Jag2 deficiency decreased oxidative stress injury, peripheral pulmonary vascular remodeling (0.276±0.020 vs. 0.451±0.033 μm, P<0.001, <50μm), and right ventricular systolic pressure (36.8±3.033 vs. 51.8±4.245 mmHg, P<0.001) in the chronic hypoxia-induced rat model of PH. Moreover, Jag2 knockdown decreased proliferation (1.227±0.051 vs. 1.45±0.07, P = 0.012), increased apoptosis (16.733%±0.724% vs. 6.56%±0.668%, P<0.001), and suppressed mitochondrial injury in hypoxia-treated rat PASMCs. Jag2 inhibition restored the activity of the Nrf2/HO-1 pathway, which was abolished by Sirtuin 1 deficiency. These findings show that Jag2 is essential for modulating pulmonary vascular dysfunction and accelerating PH, and that inhibition of Jag2 expression suppresses the progression and development of PH.

A multiscale computational model of arterial growth and remodeling including Notch signaling

Blood vessels grow and remodel in response to mechanical stimuli. Many computational models capture this process phenomenologically, by assuming stress homeostasis, but this approach cannot unravel the underlying cellular mechanisms. Mechano-sensitive Notch signaling is well-known to be key in vascular development and homeostasis. Here, we present a multiscale framework coupling a constrained mixture model, capturing the mechanics and turnover of arterial constituents, to a cell-cell signaling model, describing Notch signaling dynamics among vascular smooth muscle cells (SMCs) as influenced by mechanical stimuli. Tissue turnover was regulated by both Notch activity, informed by in vitro data, and a phenomenological contribution, accounting for mechanisms other than Notch. This novel framework predicted changes in wall thickness and arterial composition in response to hypertension similar to previous in vivo data. The simulations suggested that Notch contributes to arterial growth in hypertension mainly by promoting SMC proliferation, while other mechanisms are needed to fully capture remodeling. The results also indicated that interventions to Notch, such as external Jagged ligands, can alter both the geometry and composition of hypertensive vessels, especially in the short term. Overall, our model enables a deeper analysis of the role of Notch and Notch interventions in arterial growth and remodeling and could be adopted to investigate therapeutic strategies and optimize vascular regeneration protocols.

Vascular adaptation to cancer beyond angiogenesis: The role of PTEN

Cancer is a public health problem, and it needs blood vessels to grow. Knowing more about the processes of vascular adaptation to cancer improves our chances of attacking it, since the tumor for its extension needs such adaptation to satisfy its progressive demand for nutrients. The main objective of this review is to present the reader with some fundamental molecular pathways for vascular adaptation to cancer, highlighting within them the regulatory role of homologous tensin and phosphatase protein (PTEN). Hence the review describes vascular adaptation to cancer through somewhat known processes, such as angiogenesis, but emphasizes others that are much less explored, namely the changes in vascular reactivity and remodeling of the vascular wall -intima-media thickness and adjustments in the extracellular matrix- The role of PTEN in physiological and pathological vascular mechanisms in different types of cancer is deepened, as a crucial mediator in vascular adaptation to cancer, and points pending further exploration in cancer vascularization are suggested.

Research progress on the mechanism of phenotypic transformation of pulmonary artery smooth muscle cells induced by hypoxia

Phenotypic transformation of pulmonary artery smooth muscle cells (PASMCs) is a key factor in pulmonary vascular remodeling. Inhibiting or reversing phenotypic transformation can inhibit pulmonary vascular remodeling and control the progression of hypoxic pulmonary hypertension. Recent studies have shown that hypoxia causes intracellular peroxide metabolism to induce oxidative stress, induces multi-pathway signal transduction, including those related to autophagy, endoplasmic reticulum stress and mitochondrial dysfunction, and also induces non-coding RNA regulation of cell marker protein expression, resulting in PASMCs phenotypic transformation. This article reviews recent research progress on mechanisms of hypoxia-induced phenotypic transformation of PASMCs, which may be helpful for finding targets to inhibit phenotypic transformation and to improve pulmonary vascular remodeling diseases such as hypoxia-induced pulmonary hypertension.

Computational analysis of the role of mechanosensitive Notch signaling in arterial adaptation to hypertension

Arteries grow and remodel in response to mechanical stimuli. Hypertension, for example, results in arterial wall thickening. Cell-cell Notch signaling between vascular smooth muscle cells (VSMCs) is known to be involved in this process, but the underlying mechanisms are still unclear. Here, we investigated whether Notch mechanosensitivity to strain may regulate arterial thickening in hypertension. We developed a multiscale computational framework by coupling a finite element model of arterial mechanics, including residual stress, to an agent-based model of mechanosensitive Notch signaling, to predict VSMC phenotypes as an indicator of growth and remodeling. Our simulations revealed that the sensitivity of Notch to strain at mean blood pressure may be a key mediator of arterial thickening in hypertensive arteries. Further simulations showed that loss of residual stress can have synergistic effects with hypertension, and that changes in the expression of Notch receptors, but not Jagged ligands, may be used to control arterial growth and remodeling and to intensify or counteract hypertensive thickening. Overall, we identify Notch mechanosensitivity as a potential mediator of vascular adaptation, and we present a computational framework that can facilitate the testing of new therapeutic and regenerative strategies.

The Notch pathway attenuates burn-induced acute lung injury in rats by repressing reactive oxygen species

Background

Acute lung injury (ALI) is a common complication following severe burns. The underlying mechanisms of ALI are incompletely understood; thus, available treatments are not sufficient to repair the lung tissue after ALI.

Methods

To investigate the relationship between the Notch pathway and burn-induced lung injury, we established a rat burn injury model by scalding and verified lung injury via lung injury evaluations, including hematoxylin and eosin (H&E) staining, lung injury scoring, bronchoalveolar lavage fluid and wet/dry ratio analyses, myeloperoxidase immunohistochemical staining and reactive oxygen species (ROS) accumulation analysis. To explore whether burn injury affects Notch1 expression, we detected the expression of Notch1 and Hes1 after burn injury. Then, we extracted pulmonary microvascular endothelial cells (PMVECs) and conducted Notch pathway inhibition and activation experiments, via a γ-secretase inhibitor (GSI) and OP9-DLL1 coculture, respectively, to verify the regulatory effect of the Notch pathway on ROS accumulation and apoptosis in burn-serum-stimulated PMVECs. To investigate the regulatory effect of the Notch pathway on ROS accumulation, we detected the expression of oxidative-stress-related molecules such as superoxide dismutase, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) 2, NOX4 and cleaved caspase-3. NOX4-specific small interfering RNA (siRNA) and the inhibitor GKT137831 were used to verify the regulatory effect of the Notch pathway on ROS via NOX4.

Results

We successfully established a burn model and revealed that lung injury, excessive ROS accumulation and an inflammatory response occurred. Notch1 detection showed that the expression of Notch1 was significantly increased after burn injury. In PMVECs challenged with burn serum, ROS and cell death were elevated. Moreover, when the Notch pathway was suppressed by GSI, ROS and cell apoptosis levels were significantly increased. Conversely, these parameters were reduced when the Notch pathway was activated by OP9-DLL1. Mechanistically, the inhibition of NOX4 by siRNA and GKT137831 showed that the Notch pathway reduced ROS production and cell apoptosis by downregulating the expression of NOX4 in PMVECs.

Conclusions

The Notch pathway reduced ROS production and apoptosis by downregulating the expression of NOX4 in burn-stimulated PMVECs. The Notch-NOX4 pathway may be a novel therapeutic target to treat burn-induced ALI.

Notch4 mediates vascular remodeling via ERK/JNK/P38 MAPK signaling pathways in hypoxic pulmonary hypertension

Background

Hypoxic pulmonary hypertension (HPH) is a chronic progressive advanced disorder pathologically characterized by pulmonary vascular remodeling. Notch4 as a cell surface receptor is critical for vascular development. However, little is known about the role and mechanism of Notch4 in the development of hypoxic vascular remodeling.

Methods

Lung tissue samples were collected to detect the expression of Notch4 from patients with HPH and matched controls. Human pulmonary artery smooth muscle cells (HPASMCs) were cultured in hypoxic and normoxic conditions. Real-time quantitative PCR and western blotting were used to examine the mRNA and protein levels of Notch4. HPASMCs were transfected with small interference RNA (siRNA) against Notch4 or Notch4 overexpression plasmid, respectively. Cell viability, cell proliferation, apoptosis, and migration were assessed using Cell Counting Kit-8, Edu, Annexin-V/PI, and Transwell assay. The interaction between Notch4 and ERK, JNK, P38 MAPK were analyzed by co-immunoprecipitation. Adeno-associated virus 1-mediated siRNA against Notch4 (AAV1-si-Notch4) was injected into the airways of hypoxic rats. Right ventricular systolic pressure (RVSP), right ventricular hypertrophy and pulmonary vascular remodeling were evaluated.

Results

In this study, we demonstrate that Notch4 is highly expressed in the media of pulmonary vascular and is upregulated in lung tissues from patients with HPH and HPH rats compared with control groups. In vitro, hypoxia induces the high expression of Delta-4 and Notch4 in HPASMCs. The increased expression of Notch4 promotes HPASMCs proliferation and migration and inhibits cells apoptosis via ERK, JNK, P38 signaling pathways. Furthermore, co-immunoprecipitation result elucidates the interaction between Notch4 and ERK/JNK/P38. In vivo, silencing Notch4 partly abolished the increase in RVSP and pulmonary vascular remodeling caused by hypoxia in HPH rats.

Conclusions

These findings reveal an important role of the Notch4-ERK/JNK/P38 MAPK axis in hypoxic pulmonary remodeling and provide a potential therapeutic target for patients with HPH.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-01927-9.

Long non-coding RNA RP11-465L10.10 promotes vascular smooth muscle cells phenotype switching and MMP9 expression via the NF-κB pathway

Background

Thoracic aortic aneurysm/dissection (TAA/D) are complicated vascular disorders with rapid development and high mortality. Vascular smooth muscle cells (VSMCs) phenotype switching plays an important role in the pathological process of TAA/D. Previous studies have indicated a potential correlation between long non-coding RNA (lncRNA) RP11-465L10.10 and matrix metallopeptidase 9 (MMP9) involved in the development of TAA/D. This study aims to investigate the role of lncRNA RP11-465L10.10 in VSMCs phenotype switching and the molecular mechanism in regulating MMP9 expression.

Methods

The expression of RP11-465L10.10 in vascular tissues and in VMSCs was detected by RT-qPCR. To investigate the role of RP11-465L10.10 on VSMCs phenotype switching, an RP11-465L10.10-overexpressed lentiviral vector was constructed and transfected into VSMCs. Through EdU staining, migration assay, flow cytometry analysis, the roles of RP11-465L10.10 were estimated. Bioinformatics indicated that RP11-465L10.10 upregulating MMP9 expression via NF-κB signaling, and SN50 (a specific inhibitor of NF-κB pathway) was used to inhibit the NF-κB pathway activation, then the expression of MMP9 was detected in RP11-465L10.10 overexpressed VMSCs.

Results

In this study, we found RP11-465L10.10 and MMP9 were highly increased in TAD patient tissues, which was consistent in angiotensin II-induced VSMCs phenotype switching. RP11-465L10.10 overexpression facilitated VSMCs phenotype switching and MMP9 expression. Mechanismly, NF-κB signal pathway was involved in RP11-465L10.10 induced VSMCs phenotype switching and MMP9 expression by transcriptome data analysis and experimental confirm.

Conclusion

This study demonstrated that RP11-465L10.10 induces VSMCs phenotype switching and MMP9 expression via the NF-κB signal pathway, suggesting that RP11-465L10.10 might be a potential therapeutic target for TAA/D treatment.

Fetal Gene Reactivation in Pulmonary Arterial Hypertension: GOOD, BAD, or BOTH?

Pulmonary arterial hypertension is a debilitating chronic disorder marked by the progressive obliteration of the pre-capillary arterioles. This imposes a pressure overload on the right ventricle (RV) pushing the latter to undergo structural and mechanical adaptations that inexorably culminate in RV failure and death. Thanks to the advances in molecular biology, it has been proposed that some aspects of the RV and pulmonary vascular remodeling processes are orchestrated by a subversion of developmental regulatory mechanisms with an upregulation of a suite of genes responsible for the embryo's early growth and normally repressed in adults. In this review, we present relevant background regarding the close relationship between overactivation of fetal genes and cardiopulmonary remodeling, exploring whether the reawakening of developmental factors plays a causative role or constitutes a protective mechanism in the setting of PAH.

Progenitor/Stem Cells in Vascular Remodeling during Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is characterized by an important occlusive vascular remodeling with the production of new endothelial cells, smooth muscle cells, myofibroblasts, and fibroblasts. Identifying the cellular processes leading to vascular proliferation and dysfunction is a major goal in order to decipher the mechanisms leading to PAH development. In addition to in situ proliferation of vascular cells, studies from the past 20 years have unveiled the role of circulating and resident vascular in pulmonary vascular remodeling. This review aims at summarizing the current knowledge on the different progenitor and stem cells that have been shown to participate in pulmonary vascular lesions and on the pathways regulating their recruitment during PAH. Finally, this review also addresses the therapeutic potential of circulating endothelial progenitor cells and mesenchymal stem cells.

Pulmonary Hypertension in Acute and Chronic High Altitude Maladaptation Disorders

Alveolar hypoxia is the most prominent feature of high altitude environment with well-known consequences for the cardio-pulmonary system, including development of pulmonary hypertension. Pulmonary hypertension due to an exaggerated hypoxic pulmonary vasoconstriction contributes to high altitude pulmonary edema (HAPE), a life-threatening disorder, occurring at high altitudes in non-acclimatized healthy individuals. Despite a strong physiologic rationale for using vasodilators for prevention and treatment of HAPE, no systematic studies of their efficacy have been conducted to date. Calcium-channel blockers are currently recommended for drug prophylaxis in high-risk individuals with a clear history of recurrent HAPE based on the extensive clinical experience with nifedipine in HAPE prevention in susceptible individuals. Chronic exposure to hypoxia induces pulmonary vascular remodeling and development of pulmonary hypertension, which places an increased pressure load on the right ventricle leading to right heart failure. Further, pulmonary hypertension along with excessive erythrocytosis may complicate chronic mountain sickness, another high altitude maladaptation disorder. Importantly, other causes than hypoxia may potentially underlie and/or contribute to pulmonary hypertension at high altitude, such as chronic heart and lung diseases, thrombotic or embolic diseases. Extensive clinical experience with drugs in patients with pulmonary arterial hypertension suggests their potential for treatment of high altitude pulmonary hypertension. Small studies have demonstrated their efficacy in reducing pulmonary artery pressure in high altitude residents. However, no drugs have been approved to date for the therapy of chronic high altitude pulmonary hypertension. This work provides a literature review on the role of pulmonary hypertension in the pathogenesis of acute and chronic high altitude maladaptation disorders and summarizes current knowledge regarding potential treatment options.

Dysregulated expression of mRNA and SNP in pulmonary artery remodeling in ascites syndrome in broilers

Broiler ascites syndrome (AS), also called pulmonary artery hypertension, is a metabolic disorder that has been observed worldwide in fast-growing broilers. Pulmonary arterial remodeling is a key step in the development of AS. The precise relationship between mRNA and SNP of the pulmonary artery in regulating AS progression remains unclear. In this study, we obtained pulmonary artery tissues from broilers with AS to perform pathologic section and pathologic anatomic observation. SNP, InDel, and mRNA data analysis were carried out using GATK and ANNOVAR software to study the SNP loci of 985 previously reported genes (437 upregulated and 458 downregulated). The pathology results showed that there was a lot of yellow fluid in the abdominal cavity and pericardium, that the ascites cardiac index and hematocrit changed significantly, and that the pulmonary artery had remodeled and become thicker in the disease group. Myocardial sections showed vacuolar degeneration of myocytes and rupture of muscle fibers. In addition, ALDH7A1, IRG1, GGT5, IGSF1, DHX58, USP36, TREML2, SPAG1, CD34, and PLEKHA7 were found to be closely associated with the pathogenesis of pulmonary artery remodeling in AS progression. Taken together, our present study further illuminates the molecular mechanism of pulmonary artery remodeling underlying AS progression.

Caveolin‑1 modulates hypertensive vascular remodeling via regulation of the Notch pathway

Hypertension is one of the critical risk factors of cerebrovascular disease. Caveolin-1 (Cav-1) has been suggested to be involved in the development of hypertension; however, the underlying mechanism remains largely unknown. Therefore, the present study aimed to investigate the mechanism underlying Cav-1 in hypertension. In the present study, the hypertension model was induced by infusion of angiotensin II (Ang-II) in rats. Cell Counting Kit-8 assay was used to detect the viability of human umbilical vein endothelial cells (HUVECs). Flow cytometry was used to determine the apoptosis of HUVECs. Transmission electron microscopy was utilized to address the thickness of the vessel walls. Reverse transcription-quantitative PCR, western blotting and immunofluorescence staining were used to assess the mechanism of cav-1/Notch1 involved in hypertensive vascular remodeling. In the present study, an Ang-II-induced hypertension model was successfully established in rats. With this model, it was found that the expression levels of cav-1 and Notch1 were significantly increased in brain tissues in the hypertension group compared with the sham-operated group. In cultured HUVECs, knockdown of cav-1 regulated Ang-II-induced HUVEC viability and apoptosis, and modulated hypertensive vascular remodeling, which was mediated by the Notch pathway. The data of the present study demonstrated that the cav-1/Notch signaling plays an important role in the regulation of Ang-II-induced hypertension and vascular remodeling.

MiR-18a-5p contributes to enhanced proliferation and migration of PASMCs via targeting Notch2 in pulmonary arterial hypertension

AIM

This study is undertaken to investigate the role and molecular mechanisms of miR-18a-5p in regulating pulmonary arterial hypertension (PAH) pathogenesis.

METHODS

Gene expression and protein levels were determined by qRT-PCR and western blot, respectively; Cell counting kti-8 and Transwell migration assays were used to determine the biological functions of miR-18a-5p in pulmonary arterial smooth muscle cells (PASMCs); bioinformatics analysis, luciferase reporter assays were used to elucidate the mechanisms of miR-18a-5p.

RESULTS

MiR-18a-5p was up-regulated in the clinical samples from PAH patients. PASMCs treated with hypoxia exhibited enhanced proliferative ability and upregulated miR-18a-5p expression. Knockdown of miR-18a-5p attenuated hypoxia-induced hyper-proliferation and enhanced migratory potential of PASMCs; while miR-18a-5p overexpression promoted PASMC proliferation and migration. Further mechanistic studies showed that Notch2 was a direct target of miR-18a-5p and was repressed by miR-18a-5p overexpression. The rescue studies indicated that Notch2 overexpression counteracted the enhanced proliferation and migration induced by miR-18a-5p mimics in PASMCs. Similarly, Notch2 overexpression also block the effects caused by hypoxia in PASMCs. Moreover, Notch2 expression was down-regulated in the PAH patients and was negatively correlated with miR-18a-5p expression. In vivo animal studies further revealed the up-regulation of miR-18a-5p and the down-regulation of Notch2 in the PAH rats.

CONCLUSIONS

Collectively, this study identified the up-regulated miR-18a-5p in the PAH patients; our data suggest that miR-18a-5p contributes to the enhanced proliferation and migration of PASMCs via repressing Notch2 expression.

Quantification of uncertainty in a new network model of pulmonary arterial adventitial fibroblast pro-fibrotic signalling

Here, we present a novel network model of the pulmonary arterial adventitial fibroblast (PAAF) that represents seven signalling pathways, confirmed to be important in pulmonary arterial fibrosis, as 92 reactions and 64 state variables. Without optimizing parameters, the model correctly predicted 80% of 39 results of input-output and inhibition experiments reported in 20 independent papers not used to formulate the original network. Parameter uncertainty quantification (UQ) showed that this measure of model accuracy is robust to changes in input weights and half-maximal activation levels (EC50), but is more affected by uncertainty in the Hill coefficient (n), which governs the biochemical cooperativity or steepness of the sigmoidal activation function of each state variable. Epistemic uncertainty in model structure, due to the reliance of some network components and interactions on experiments using non-PAAF cell types, suggested that this source of uncertainty had a smaller impact on model accuracy than the alternative of reducing the network to only those interactions reported in PAAFs. UQ highlighted model parameters that can be optimized to improve prediction accuracy and network modules where there is the greatest need for new experiments. This article is part of the theme issue 'Uncertainty quantification in cardiac and cardiovascular modelling and simulation'.

Therapeutic potential of KLF2-induced exosomal microRNAs in pulmonary hypertension

Pulmonary arterial hypertension (PAH) is a severe disorder of lung vasculature that causes right heart failure. Homoeostatic effects of flow-activated transcription factor Krüppel-like factor 2 (KLF2) are compromised in PAH. Here, we show that KLF2-induced exosomal microRNAs, miR-181a-5p and miR-324-5p act together to attenuate pulmonary vascular remodelling and that their actions are mediated by Notch4 and ETS1 and other key regulators of vascular homoeostasis. Expressions of KLF2, miR-181a-5p and miR-324-5p are reduced, while levels of their target genes are elevated in pre-clinical PAH, idiopathic PAH and heritable PAH with missense p.H288Y KLF2 mutation. Therapeutic supplementation of miR-181a-5p and miR-324-5p reduces proliferative and angiogenic responses in patient-derived cells and attenuates disease progression in PAH mice. This study shows that reduced KLF2 signalling is a common feature of human PAH and highlights the potential therapeutic role of KLF2-regulated exosomal miRNAs in PAH and other diseases associated with vascular remodelling.

Pleiotropic microRNA-21 in pulmonary remodeling: novel insights for molecular mechanism and present advancements

MicroRNA-21 (miR-21), probably one of the most studied miRNAs to date, is found pleiotropic in various biological events. Its emerging role in pulmonary remodeling has attracted extensive attention. This review summarizes the genomic information of its primary transcript and various transcriptional regulations on its promoter. In addition, the role of miR-21 in pulmonary remodeling related signaling such as transforming growth factor β (TGF-β), bone morphogenetic protein (BMP), epidermal growth factor receptor (EGFR) and Notch signaling is discussed. Various validated miR-21 target genes participate in controlling of the overactive cell accumulation, smooth muscle contraction, inflammatory stress (trigger for lung epithelium damage), extracellular matrix deposition and hypoxia-induced disorders. Moreover, we focus on its particular implication in events including inflammatory stress-driven epithelium damage, epithelial-to-mesenchymal transition (EMT), transdifferentiation of fibroblasts into myofibroblasts, hypoxia stimuli and ROS response, as well as some other pulmonary remodeling related events such as overactive fibroblast (myofibroblast) accumulation, extracellular matrix deposition, and angiogenesis. Here, we summarize the strong potential of miR-21 in pulmonary remodeling and provide novel clues for further research in this area.

Exploration of the Notch3-HES5 signal pathway in monocrotaline-induced pulmonary hypertension using rat model

OBJECTIVE

This study explores the role of the Notch3-HES5 signal pathway in monocrotaline-induced pulmonary hypertension (PH) using rat models.

METHOD

Sprague Dawley rats (n = 45) were randomly grouped into normal group, control group, and model group. Rats in the model group were used to establish the PH rat model. Four weeks after model establishment, right catheterization was used to measure the mean pulmonary arterial pressure (mPAP) and right ventricular systolic pressure (RVSP) to analyze hemodynamic changes. The severity of PH was assessed by the right ventricular hypertrophy index (RVHI) and percentage of media thickness (MT%). The expressions of Notch3 and HES5 were determined by ELISA and reverse transcription-polymerase chain reaction. The correlation of mRNA expressions of Notch3 and HES5 with mPAP was analyzed.

RESULTS

Rats in the model group had higher mPAP, RVSP, RVHI, and MT% as well as thicker pulmonary arterioles wall than those in the normal group. Immunohistochemistry showed Notch3 and HES5 were mainly expressed in the smooth muscle cell in pulmonary arterioles. In comparison with the normal group, rats in the model group had elevated expressions of Notch3 and HES5. The mean pulmonary arterial pressure was positively related with mRNA expressions of Notch3 and HES5.

CONCLUSION

Taken together, our study demonstrates that monocrotaline-induced PH rats had high expressions of the Notch3-HES5 signal pathway in the pulmonary arterioles. The signal of the Notch3-HES5 signal pathway was positively related to the hemodynamics of the lung vasculature.

Dysregulated expression of microRNAs and mRNAs in pulmonary artery remodeling in ascites syndrome in broiler chickens

Ascites syndrome (AS), also known as pulmonary artery hypertension, remains a challenging disease that severely affects both humans and broiler chickens. Pulmonary artery remodeling presents a key step in the development of AS. In this study, we obtained pulmonary artery tissues from broilers with and without AS to perform miRNA sequencing analysis, miRNA-mRNA association analysis and pathological examinations. 29 significantly differentially expressed miRNAs were found both in known and novel miRNAs with 18 up-regulated and 11 down-regulated miRNAs. Their predicted potential targets were involved in a wide range of functional clusters as indicated via GO (Gene Ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) analyses. The upregulation of miR-155, miR-23b-3p, miR-146b-5p and miR-146b-3p were found closely associated with the pathogenesis of pulmonary artery remodeling in AS progression. The association analysis for the miRNAs-mRNAs showed that these 29 significantly differentially expressed miRNAs regulate 162 differentially expressed target genes. Among them, 20 miRNAs correlated with 18 predicted target genes that appear to be involved in pulmonary artery remodeling, mainly in three broad physiological processes: the hypoxia sensing response (HIF1α, NHE1, STAT5 and STAT3), endothelial permeability dysfunction (CD44, TRAF2, CDK2AP1, LZTFL1, JAZF1, PEBP1, LRP1B, RPS14 and THBS2) and inflammation (MEOX2, STAT5, STAT3, IRF8, MAP3K8, IL-1BETA and TNFRSF1B). Pathological pulmonary artery remodeling in the AS broilers was consistently observed in the present study. Taken together, the current analysis further illuminates the molecular mechanism of pulmonary artery remodeling underlying AS progression.

mTOR-Notch3 signaling mediates pulmonary hypertension in hypoxia-exposed neonatal rats independent of changes in autophagy

BACKGROUND/AIM

Mammalian target of rapamycin (mTOR) is a pivotal regulator of cell proliferation, survival, and autophagy. Autophagy is increased in adult experimental chronic pulmonary hypertension (PHT), but its contributory role to pulmonary vascular disease remains uncertain and has yet to be explored in the neonatal animal. Notch is a major pro-proliferative pathway activated by mTOR. A direct relationship between autophagy and Notch signaling has not been previously explored. Our aim was to examine changes in mTOR-, Notch-, and autophagy-related pathways and the therapeutic effects of autophagy modulators in experimental chronic neonatal PHT secondary to chronic hypoxia.

METHODS

Rat pups were exposed to normoxia or hypoxia (13% O₂ ) from postnatal days 1-21, while receiving treatment with temsirolimus (mTOR inhibitor), DAPT (Notch inhibitor), or chloroquine (inhibitor of autophagic flux).

RESULTS

Exposure to hypoxia up-regulated autophagy and Notch3 signaling markers in lung, pulmonary artery (PA), and PA-derived smooth muscle cells (SMCs). Temsirolimus prevented chronic PHT and attenuated PA and SMC signaling secondary to hypoxia. These effects were replicated by DAPT. mTOR or Notch inhibition also down-regulated smooth muscle content of platelet-derived growth factor β-receptor, a known contributor to vascular remodeling. In contrast, chloroquine had no modifying effects on markers of chronic PHT. Knockdown of Beclin-1 in SMCs had no effect on hypoxia-stimulated Notch3 signaling.

CONCLUSIONS

mTOR-Notch3 signaling plays a critical role in experimental chronic neonatal PHT. Inhibition of autophagy did not suppress Notch signaling and had no effect on markers of chronic PHT.

Notch Signaling in Endothelial Cells: Is It the Therapeutic Target for Vascular Neointimal Hyperplasia?

Blood vessels respond to injury through a healing process that includes neointimal hyperplasia. The vascular endothelium is a monolayer of cells that separates the outer vascular wall from the inner circulating blood. The disruption and exposure of endothelial cells (ECs) to subintimal components initiate the neointimal formation. ECs not only act as a highly selective barrier to prevent early pathological changes of neointimal hyperplasia, but also synthesize and release molecules to maintain vascular homeostasis. After vascular injury, ECs exhibit varied responses, including proliferation, regeneration, apoptosis, phenotypic switching, interacting with other cells by direct contact or secreted molecules and the change of barrier function. This brief review presents the functional role of the evolutionarily-conserved Notch pathway in neointimal hyperplasia, notably by regulating endothelial cell functions (proliferation, regeneration, apoptosis, differentiation, cell-cell interaction). Understanding endothelial cell biology should help us define methods to prompt cell proliferation, prevent cell apoptosis and dysfunction, block neointimal hyperplasia and vessel narrowing.

Current understanding of the pathophysiology of chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is a unique form of pulmonary hypertension arising from fibrotic obliteration of major pulmonary arteries. Pro-thrombotic states, large clot burden and impaired dissolution are believed to contribute to the occurrence and progression of thrombosis after an acute pulmonary embolic event. Recent data utilizing several models have facilitated the understanding of clot resolution. This review summarizes current knowledge on pathophysiological mechanisms of major vessel occlusion in CTEPH.

Hypoxia-Induced Mitogenic Factor Acts as a Nonclassical Ligand of Calcium-Sensing Receptor, Therapeutically Exploitable for Intermittent Hypoxia-Induced Pulmonary Hypertension

Hypoxia-induced mitogenic factor (HIMF) is an inflammatory cytokine playing important role(s) in the development of hypoxic pulmonary hypertension. The molecular target mediating HIMF-stimulated downstream events remains unclear. The coimmunoprecipitation screen identified extracellular calcium-sensing receptor (CaSR) as the binding partner for HIMF in pulmonary artery smooth muscle cells. The yeast 2-hybrid assay then revealed the binding of HIMF to the intracellular, not the extracellular, domain of extracellular CaSR. The binding of HIMF enhanced the activity of extracellular CaSR and mediated hypoxia-evoked proliferation of pulmonary artery smooth cells and the development of pulmonary vascular remodeling and pulmonary hypertension, all of which was specifically attenuated by a synthesized membrane-permeable peptide flanking the core amino acids of the intracellular binding domain of extracellular CaSR. Thus, HIMF induces pulmonary hypertension as a nonclassical ligand of extracellular CaSR, and the binding motif of extracellular CaSR can be therapeutically exploitable.

Role of Jagged1-Hey1 Signal in Angiotensin II-induced Impairment of Myocardial Angiogenesis

BACKGROUND

Angiotensin II (Ang II) is a major contributor to the development of heart failure. However, the molecular and cellular mechanisms that underlie this process remain elusive. Inadequate angiogenesis in the myocardium leads to a transition from cardiac hypertrophy to dysfunction, and our previous study showed that Ang II significantly impaired the angiogenesis response. The current study was designed to examine the role of Jagged1-Notch signaling in the effect of Ang II during impaired angiogenesis and cardiac hypertrophy.

METHODS

Ang II was subcutaneously infused into 8-week-old male C57BL/6 mice at a dose of 200 ng·kg-1·min-1 for 2 weeks using Alzet micro-osmotic pumps. N-[N-(3, 5-difluorophenacetyl)-L-alanyl]-S-phenylglycine tert-butyl ester (DAPT), a γ-secretase inhibitor, was injected subcutaneously during Ang II infusion at a dose of 10.0 mg·kg-1·d-1. Forty mice were divided into four groups (n = 10 per group): control group; Ang II group, treated with Ang II; DAPT group, treated with DAPT; and Ang II + DAPT group, treated with both Ang II and DAPT. At the end of experiments, myocardial (left ventricle [LV]) tissue from each experimental group was evaluated using immunohistochemistry, Western blotting, and real-time polymerase chain reaction. Data were analyzed using one-way analysis of variance test followed by the least significant difference method or independent samples t-test.

RESULTS

Ang II treatment significantly induced cardiac hypertrophy and impaired the angiogenesis response compared to controls, as shown by hematoxylin and eosin (HE) staining and immunohistochemistry for CD31, a vascular marker (P < 0.05 for both). Meanwhile, Jagged1 protein was significantly increased, but gene expression for both Jag1 and Hey1 was decreased in the LV following Ang II treatment, compared to that in controls (relative ratio for Jag1 gene: 0.45 ± 0.13 vs. 0.84 ± 0.15; relative ratio for Hey1 gene: 0.51 ± 0.08 vs. 0.91 ± 0.09; P < 0.05). All these cellular and molecular effects induced by Ang II in the hearts of mice were reduced by DAPT treatment. Interestingly, Ang II stimulated Hey1, a known Notch target, but did not affect the expression of Hey2, another Notch target gene.

CONCLUSIONS

A Jagged1-Hey1 signal might mediate the impairment of angiogenesis induced by Ang II during cardiac hypertrophy.

The role of endoglin in post-ischemic revascularization

Following arterial occlusion, blood vessels respond by forming a new network of functional capillaries (angiogenesis), by reorganizing preexisting capillaries through the recruitment of smooth muscle cells to generate new arteries (arteriogenesis) and by growing and remodeling preexisting collateral arterioles into physiologically relevant arteries (collateral development). All these processes result in the recovery of organ perfusion. The importance of endoglin in post-occlusion reperfusion is sustained by several observations: (1) endoglin expression is increased in vessels showing active angiogenesis/remodeling; (2) genetic endoglin haploinsufficiency in humans causes deficient angiogenesis; and (3) the reduction of endoglin expression by gene disruption or the administration of endoglin-neutralizing antibodies reduces angiogenesis and revascularization. However, the precise role of endoglin in the several processes associated with revascularization has not been completely elucidated and, in some cases, the function ascribed to endoglin by different authors is controversial. The purpose of this review is to organize in a critical way the information available for the role of endoglin in several phenomena (angiogenesis, arteriogenesis and collateral development) associated with post-ischemic revascularization.

Gene expression profiling of common signal transduction pathways affected by rBMSCs/F92A-Cav1 in the lungs of rat with pulmonary arterial hypertension

BACKGROUND

Pulmonary arterial hypertension (PAH) is associated with sustained vasoconstriction, inflammation and suppressed apoptosis of smooth muscle cells. Our previous studies have found that rat bone marrow-derived mesenchymal stem cells (rBMSCs) transduced with a mutant caveolin-1(F92A-Cav1) could enhance endothelial nitric oxide synthase (eNOS) activity and improve pulmonary vascular remodeling, but the potential mechanism is not yet fully explored. The present study was to investigate the gene expression profile upon rBMSCs/F92A-Cav1delivered to PAH rat to evaluate the role of F92A-Cav1 in its regulation.

METHODS

PAH was induced with monocrotaline (MCT, 60mg/kg) prior to delivery of lentiviral vector transduced rBMSCs expressing Cav1 or F92A-Cav1. Gene expression profiling was performed using Rat Signal Transduction PathwayFinder array. The expression changes of 84 key genes representing 10 signal transduction pathways in rat following rBMSCs/F92A-Cav1 treatment was examined.

RESULTS

Screening with the Rat Signal Transduction PathwayFinder R² PCR Array system and subsequent western blot, immunohistochemistry or real time PCR analysis revealed that F92A-Cav1 modified rBMSCs can inhibit the inflammation factors (TNF-alpha, Icam1 and C/EBPdelta), pro-proliferation genes (c-Myc, Bcl2a1d, Notch1and Hey2), oxidative stress gene (Hmox1) and activate cell cycle arrested gene Cdkn1a, ameliorating inflammation and inhibiting cell proliferation in PAH rat.

CONCLUSION

rBMSCs/F92A-Cav1 inhibits inflammation and cell proliferation by regulating signaling pathways that related to inflammation, proliferation, cell cycle and oxidative stress.

Gamma-secretase Inhibitor Prevents Proliferation and Migration of Ductus Arteriosus Smooth Muscle Cells through the Notch3-HES1/2/5 Pathway

Patent ductus arteriosus (PDA) can cause morbidity and mortality in neonates. Vascular remodeling, characterized by proliferation and migration of smooth muscle cells (SMCs), is an essential process for postnatal DA closure. Notch signaling is an important mediator of vascular remodelling but its role in DA is unkonwn. We investigated the effects and underlying mechanisms of γ-secretase inhibitor DAPT, a Notch signaling inhibitor on angiotensin II (Ang II)-induced proliferation and migration of DASMCs. Proliferation and migration of DASMCs cultured from neonatal Wistar rats were induced by Ang II, with or without DAPT pre-treatment. In addition, potential underlying mechanisms including cell cycle progression, Ca(2+) influx, reactive oxygen species (ROS) production, signal transduction of MAPK and Akt, and Notch receptor with its target gene pathway were examined. We found that DAPT inhibited Ang II-induced DASMCs proliferation and migration dose dependently. DAPT also arrested the cell cycle progression in the G0/G1-phase, and attenuated calcium overload and ROS production caused by Ang II. Moreover, DAPT inhibited nuclear translocation of Notch3 receptor intracellular domain, with decreased expression of its down-stream genes including HES1, HES2 and HES5. Finally, Ang II-activated ERK1/2, JNK and Akt were also counteracted by DAPT. In conclusion, DAPT inhibits Ang II-induced DASMCs proliferation and migration. These effects are potentially mediated by decreased calcium influx, reduced ROS production, and down-regulation of ERK1/2, JNK and Akt, through the Notch3-HES1/2/5 pathway. Therefore, Notch signaling has a role in DA remodeling and may provide a target pathway for therapeutic intervention of PDA.

Transcriptome Analysis and Gene Identification in the Pulmonary Artery of Broilers with Ascites Syndrome

BACKGROUND

Pulmonary arterial hypertension, also known as Ascites syndrome (AS), remains a clinically challenging disease with a large impact on both humans and broiler chickens. Pulmonary arterial remodeling presents a key step in the development of AS. The precise molecular mechanism of pulmonary artery remodeling regulating AS progression remains unclear.

METHODOLOGY/PRINCIPAL FINDINGS

We obtained pulmonary arteries from two positive AS and two normal broilers for RNA sequencing (RNA-seq) analysis and pathological observation. RNA-seq analysis revealed a total of 895 significantly differentially expressed genes (DEGs) with 437 up-regulated and 458 down-regulated genes, which were significantly enriched to 12 GO (Gene Ontology) terms and 4 KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways (Padj<0.05) regulating pulmonary artery remodeling and consequently occurrence of AS. These GO terms and pathways include ribosome, Jak-STAT and NOD-like receptor signaling pathways which regulate pulmonary artery remodeling through vascular smooth cell proliferation, inflammation and vascular smooth cell proliferation together. Some notable DEGs within these pathways included downregulation of genes like RPL 5, 7, 8, 9, 14; upregulation of genes such as IL-6, K60, STAT3, STAT5 Pim1 and SOCS3; IKKα, IkB, P38, five cytokines IL-6, IL8, IL-1β, IL-18, and MIP-1β. Six important regulators of pulmonary artery vascular remodeling and construction like CYP1B1, ALDH7A1, MYLK, CAMK4, BMP7 and INOS were upregulated in the pulmonary artery of AS broilers. The pathology results showed that the pulmonary artery had remodeled and become thicker in the disease group.

CONCLUSIONS/SIGNIFICANCE

Our present data suggested some specific components of the complex molecular circuitry regulating pulmonary arterial remodeling underlying AS progression in broilers. We revealed some valuable candidate genes and pathways that involved in pulmonary artery remodeling further contributing to the AS progression.

Crosstalk of dynamic functional modules in lung development of rhesus macaques

Lung development follows a complex series of dynamic histogenic events that depend on the fluctuation of gene expression, and the disruption of gene regulation could lead to devastating consequences, such as diseases in adulthood. In order to investigate the mechanism of lung development, we performed RNA sequencing by Illumina HiSeq™ 2000 to measure mRNA expression in lung tissues of nine rhesus macaques spanning from foetuses at gestation of 45 days to postnatal at 7 days. This development period was divided into three developmental stages, including the early stage (45-100 gestational days), the middle stage (137-163 gestational days) and the late stage (after birth at 4-7 days). Firstly, we identified stage-specific genes, based on which we found that the principle biological processes of the early stage were mainly associated with internal growth signalling, while the middle and late stage-specific genes controlled the external stress signalling. Then, we constructed a stage-specific protein-protein interaction (PPI) subnetwork, extracted dynamic modules, and identified crosstalk between modules. Moreover, we found four active pathways that could mediate the crosstalk, including the Notch signalling pathway, cell cycle, NOD-like receptor signalling pathway, and Toll-like receptor signalling pathway. These pathways not only played crucial roles in lung development, but also were implicated in lung diseases. Finally, some important bridgers, such as PSEN2, HSP90AA1 and CASP8, were discovered to explain the potential mechanism of crosstalk. Therefore, our study presents the landscape of gene expression of lung development of rhesus macaques, and provides an extended insight into the lung development mechanism.

Novel homozygous BMP9 nonsense mutation causes pulmonary arterial hypertension: a case report

BACKGROUND

Pulmonary arterial hypertension (PAH) is a rare, progressive, fatal vascular disorder. Genetic predisposition plays vital roles in the development of PAH, with most mutations being identified in genes involved in the transforming growth factor beta (TGF-β) signaling pathways. Defects in the BMP9 gene have been documented in hereditary hemorrhagic telangiectasia (HHT), the most common inherited vascular disorder, which is occasionally associated with PAH. Selective enhancement of endothelial BMPR2 with BMP9 reverses pulmonary arterial hypertension.

CASE PRESENTATION

We report the case of a 5-year-old Hispanic boy who was diagnosed with severe PAH and right heart failure at 3 years of age. During his stay in the pediatric intensive care unit, treatment was initiated with inhaled nitric oxide and intravenous epoprostenol; he subsequently was transitioned to treprostinil, sildenafil, and prophylactic enoxaparin. Now, two years later, the child is asymptomatic on sildenafil, bosentan, subcutaneous treprostinil, and warfarin. Genetic screening revealed a novel homozygous nonsense mutation in the BMP9 gene (c.76C > T; p.Gln26Ter). The child had no telangiectasias or arteriovenous malformations; family history also was negative. Subsequent parental testing showed both parents were heterozygous for the same mutation, indicating that the child inherited the BMP9 mutant allele from each parent.

CONCLUSION

To our knowledge, this is the first report of a BMP9 mutation in a patient with PAH. The homozygous nonsense mutation may account for the early onset and severity of PAH in this patient and also fit the 'two-hit' model we proposed previously. The absence of clinical symptoms for PAH in the parents may be due to incomplete penetrance or various expressivities of the BMP9 mutations. Our study expands the spectrum of phenotypes related to BMP9 mutations.

Human lung microRNA profiling in pulmonary arterial hypertension secondary to congenital heart defect

OBJECTIVE

Although several microRNAs were reported to play essential roles in pulmonary artery hypertension due to hypoxia or monocrotaline, their potential role in pulmonary arterial hypertension secondary to congenital heart disease is largely unknown. This study aimed to indentify microRNAs implicated in pulmonary arterial hypertension secondary to congenital heart disease in children.

METHODS

Using microRNAs microarray, we profiled the microRNAs in the lung specimen from 12 congenital heart disease patients, (6 with pulmonary arterial hypertension and the others without). We validated the microRNAs expression using RT-PCR experiments. Then, we predicted the target genes of the promising microRNAs by bioinformatical analysis and verified its regulating role by luciferase assay and western blot experiments.

RESULTS

All the 12 patients were uneventfully recovered from cardiac surgery. Comparing to the non-pulmonary arterial hypertension lung tissue, 62 microRNAs were significantly up-regulated and 12 were significantly de-regulated in the pulmonary arterial hypertension lung tissue. Among them 27 microRNAs reached P values ≤ 0.05, we validated the up-regulation of microRNA-27b by RT-PCR experiments and found the expression level of microRNA-27b was correlated with preoperative mean pulmonary arterial pressure. In vitro, overexpression of microRNA-27b decreased the protein expression of NOTCH1 and significantly reduced luciferase activity.

CONCLUSIONS

The current study revealed for the first time that microRNAs may be important regulators in pulmonary arterial hypertension secondary to congenital heart disease, and demonstrated the correlation between microRNA-27b and pulmonary arterial hypertension with the implication of NOTCH1.

Pulmonary arterial wall thickness in Eisenmenger Syndrome: Prospective, cross-sectional, controlled clinical trial

BACKGROUND

The aim of current study is to investigate echocardiographic pulmonary artery wall thickness (PAWT) association with angiocardiography, echocardiography, and biochemical findings and to demonstrate its predictive role in morbidity of disease.

METHOD

Nineteen patients with Eisenmenger Syndrome (ES) (13 females; a mean age of 12.0 ± 4.1 [min-max 4-17] years) and 24 (16 females; a mean age of 12.1 ± 4.3 [min-max 3-18 years]) healthy subjects as a control group were included in this prospective, cross-sectional, controlled clinical study between December, 2012 and December, 2013. PAWT were measured at the end of systole at the distal site of pulmonary valves at the parasternal short-axis. PAWT was compared with morbidity criteria of the disease such as functional class, pulmonary vascular resistance.

RESULTS

PAWT was higher in the patient group (P = 0.005) together with pulmonary arterial diameter (Z-score, P < 0.001), vena cava inferior diameter (P = 0.002), and right ventricular wall thickness (RVWT), while TAPSE was significantly lower (P = 0.002). PAWT was strongly positively correlated to RVWT (r = 0.893, P < 0.001) and moderate negatively correlated to TAPSE (r = 0.597; P < 0.011).

CONCLUSION

PAWT can be used as an additional parameter with other echocardiographic parameters in the follow-up of Eisenmenger Syndrome in children.

Sodium Hydroxide Pinpoint Pressing Permeation Method for the Animal Modeling of Sick Sinus Syndrome

Sodium hydroxide pinpoint pressing permeation (SHPPP) was investigated in order to build a rat model of sick sinus syndrome (SSS), which is easy to operate and control the degree of damage, with fewer complications and applicable for large and small animals.Thirty healthy Wistar rats (15 males and 15 females, weighing 250-350 g) were randomly divided into 3 groups, namely a formaldehyde thoracotomy wet compressing group (FTWC), formaldehyde pinpoint pressing permeation group (FPPP) group, and SHPPP group. The number of surviving rats, heart rate (HR), sinoatrial node recovery time (SNRT), corrected SNRT (CSNRT), and sinoatrial conduction time (SACT) were recorded 3 days, one week, and two weeks after modeling.The achievement ratio of modeling was 10% in the FTWC group, 40% in the FPPP group, and 70% in the SHPPP group, and the differences were statistically significant (χ(2) = 7.250, P = 0.007). Meanwhile, the HR was reduced by about 37% in these 3 groups 3 days after modeling, while the reduction was maintained only in SHPPP (P > 0.05) and the HR was re-elevated in the FTWC and FPPP groups 2 weeks after modeling (P < 0.05). Additionally, the SNRT, cS-NRT, and SACT were significantly prolonged compared with pre-modeling in all 3 groups (P < 0.01).SHPPP was the best method with which to build an SSS model with stable and lasting low HR and high success rate of modeling, which might be helpful for further studies on the SSS mechanisms and drugs.

Disruption of miR-29 Leads to Aberrant Differentiation of Smooth Muscle Cells Selectively Associated with Distal Lung Vasculature

Differentiation of lung vascular smooth muscle cells (vSMCs) is tightly regulated during development or in response to challenges in a vessel specific manner. Aberrant vSMCs specifically associated with distal pulmonary arteries have been implicated in the pathogenesis of respiratory diseases, such as pulmonary arterial hypertension (PAH), a progressive and fatal disease, with no effective treatment. Therefore, it is highly relevant to understand the underlying mechanisms of lung vSMC differentiation. miRNAs are known to play critical roles in vSMC maturation and function of systemic vessels; however, little is known regarding the role of miRNAs in lung vSMCs. Here, we report that miR-29 family members are the most abundant miRNAs in adult mouse lungs. Moreover, high levels of miR-29 expression are selectively associated with vSMCs of distal vessels in both mouse and human lungs. Furthermore, we have shown that disruption of miR-29 in vivo leads to immature/synthetic vSMC phenotype specifically associated with distal lung vasculature, at least partially due to the derepression of KLF4, components of the PDGF pathway and ECM-related genes associated with synthetic phenotype. Moreover, we found that expression of FBXO32 in vSMCs is significantly upregulated in the distal vasculature of miR-29 null lungs. This indicates a potential important role of miR-29 in smooth muscle cell function by regulating FBXO32 and SMC protein degradation. These results are strongly supported by findings of a cell autonomous role of endogenous miR-29 in promoting SMC differentiation in vitro. Together, our findings suggested a vessel specific role of miR-29 in vSMC differentiation and function by targeting several key negative regulators.

The pathogenesis of some vascular diseases, such as PAH is selectively associated with aberrant differentiation and proliferation of vSMCs of distal arteries. While significant progresses have been made in understanding the core mechanism of differentiation and proliferation of vSMCs, little is known regarding vessel specific regulations. By investigating the expression and function of miR-29 in vivo, we found a vessel selective enriched expression and function of miR-29 during mouse lung development. Interestingly, disruption of miR-29 results in defects in vSMCs differentiation of distal vessels, reminiscent of vSMC phenotype observed in the early stage of PAH in which immature/synthetic vSMCs of distal arteries failed to differentiate and were unable to tune down the expression of collagens and other extracellular-related genes. This is the first evidence that miR-29 selectively regulates vSMCs differentiation and vessel wall formation. Future implications are to study the expression and function of miR-29 in human pulmonary vascular diseases, which might lead to establishing miR-29 as a therapeutic target for disease intervention.

The Notch γ-secretase inhibitor ameliorates kidney fibrosis via inhibition of TGF-β/Smad2/3 signaling pathway activation

Kidney fibrosis is a common feature of chronic kidney disease (CKD). A recent study suggests that abnormal Notch signaling activation contributes to the development of renal fibrosis. However, the molecular mechanism that regulates this process remains unexplored. Unilateral ureteral obstruction (UUO) or sham-operated C57BL6 mice (aged 10 weeks) were randomly assigned to receive dibenzazepine (DBZ, 250 μg/100g/d) or vehicle for 7 days. Histologic examinations were performed on the kidneys using Masson's trichrome staining and immunohistochemistry. Real-time PCR and western blot analysis were used for detection of mRNA expression and protein phosphorylation. The expression of Notch 1, 3, and 4, Notch intracellular domain (NICD), and its target genes Hes1 and HeyL were upregulated in UUO mice, while the increase in NICD protein was significantly attenuated by DBZ. After 7 days, the severity of renal fibrosis and expression of fibrotic markers, including collagen 1α1/3α1, fibronectin, and α-smooth muscle actin, were markedly increased in UUO compared with sham mice. In contrast, administration of DBZ markedly attenuated these effects. Furthermore, DBZ significantly inhibited UUO-induced expression of transforming growth factor (TGF)-β, phosphorylated Smad 2, and Smad 3. Mechanistically, Notch signaling activation in tubular epithelial cells enhanced fibroblast proliferation and activation in a coculture experiment. Our study provides evidence that Notch signaling is implicated in renal fibrogenesis. The Notch inhibitor DBZ can ameliorate this process via inhibition of the TGF-β/Smad2/3 signaling pathway, and might be a novel drug for preventing chronic kidney disease.

Endothelial progenitor cells and pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a progressive disease characterised by lung endothelial cell dysfunction and vascular remodelling. A number of studies now suggest that endothelial progenitor cells (EPCs) may induce neovascularisation and could be a promising approach for cell based therapy for PAH. On the contrary EPCs may contribute to pulmonary vascular remodelling, particularly in end-stage pulmonary disease. This review article will provide a brief summary of the relationship between PAH and EPCs, the application of the EPCs to PAH and highlight the potential clinical application of the EPCs cell therapy to PAH.

Soluble JAGGED1 inhibits pulmonary hypertension by attenuating notch signaling

OBJECTIVE

Notch signaling has been implicated in the development of pulmonary arterial hypertension (PH) as reflected by increased expression of Notch member proteins that induce the proliferation of pulmonary arterial smooth muscle cells (PASMCs). Soluble Jagged1 (sJag1) has been shown to inhibit Notch signaling in vitro and in vivo; however, its capacity to suppress PH remains unknown.

APPROACH AND RESULTS

Notch1, Notch3, Jagged1, and Herp2 protein were highly expressed in both the mouse model of hypoxia-induced PH and the rat model of monocrotaline-induced PH. By attenuation and reversal of multiple pathological processes that were associated with PH, adenoviral sJag1 transfection significantly reduced the proliferation and enhanced the apoptosis of PASMCs in PH, whereas vehicle had no effect. The sJag1 inhibitory effect on Notch activation is likely related to its interference with ligand-induced signaling. Importantly, the administration with adenoviral sJag1 improved the survival rate of PH rats. Furthermore, sJag1 can restore the PH-PASMCs phenotype from the dedifferentiated to the differentiated state, by giving a positive effect on the physical binding of myocardin to the CC(A/T)nGG (CArG)-containing regions of vascular smooth muscle cells-specific promoters.

CONCLUSIONS

Our results demonstrated that the potential therapeutic use of the sJag1 may not only inhibit the proliferation of PASMCs but also restore the PH-PASMCs phenotype from the dedifferentiated to the differentiated state through interference with Notch-Herp2 signaling.