Transforming growth factor-β(1) represses bone morphogenetic protein-mediated Smad signaling in pulmonary artery smooth muscle cells via Smad3

LncRNA MYOSLID contributes to PH via targeting BMPR2 signaling in pulmonary artery smooth muscle cell

BACKGROUND/OBJECTIVE

The pathogenesis and vascular remodeling during pulmonary hypertension (PH) have been associated with dysregulation of bone morphogenetic protein receptor type 2 (BMPR2) and transforming growth factor-β (TGF-β) signaling in pulmonary artery smooth muscle cells (PASMCs). Evidence suggests that the human-specific lncRNA MYOSLID is a transcriptional target of the TGF-β/SMAD pathway. In this study, we investigated the involvement of MYOSLID in the pathogenesis of PH.

METHODS

Lung tissues from PH patients and rat PH models were analyzed to assess clinical relevance. RNA-Seq was performed to identify target genes. Pulmonary artery smooth muscle cells (PASMCs) were used to evaluate function and underlying mechanisms.

RESULTS

RNA-Seq analysis of PASMCs stimulated by TGF-β1 revealed significantly dysregulated lncRNAs. MYOSLID expression was markedly elevated in lung tissues from PH patients and in PASMCs stimulated with TGF-β1. Mechanistically, loss of MYOSLID inhibited the TGF-β pathway by reducing SMAD2/3 PHosphorylation and activated the BMPR2 pathway by enhancing SMAD1/5/9 phosphorylation and increasing ID genes expression in PASMCs. DAZAP2, a target gene of MYOSLID, functions as an inhibitor of BMPR2 signaling. Moreover, DAZAP2 expression was significantly elevated in lung tissues from PH patients and rat PH models. Functionally, knockdown of MYOSLID and DAZAP2 reduced proliferation, migration, and apoptosis resistance in PASMCs.

CONCLUSION

The activation of the MYOSLID-DAZAP2-BMPR2 axis contributes to pulmonary vascular remodeling, and targeting MYOSLID and DAZAP2 may represent novel therapeutic strategies for PH treatment.

Analysis of MicroRNA Cargo in Circulating Extracellular Vesicles from HIV-Infected Individuals with Pulmonary Hypertension

The risk of developing pulmonary hypertension (PH) in people living with HIV is at least 300-fold higher than in the general population, and illicit drug use further potentiates the development of HIV-associated PH. The relevance of extracellular vesicles (EVs) containing both coding as well as non-coding RNAs in PH secondary to HIV infection and drug abuse is yet to be explored. We here compared the miRNA cargo of plasma-derived EVs from HIV-infected stimulant users with (HIV + Stimulants + PH) and without PH (HIV + Stimulants) using small RNA sequencing. The data were compared with 12 PH datasets available in the GEO database to identify potential candidate gene targets for differentially altered miRNAs using the following functional analysis tools: ingenuity pathway analysis (IPA), over-representation analysis (ORA), and gene set enrichment analysis (GSEA). MiRNAs involved in promoting cell proliferation and inhibition of intrinsic apoptotic signaling pathways were among the top upregulated miRNAs identified in EVs from the HIV + Stimulants + PH group compared to the HIV + Stimulants group. Alternatively, the downregulated miRNAs in the HIV + Stimulants + PH group suggested an association with the negative regulation of smooth muscle cell proliferation, IL-2 mediated signaling, and transmembrane receptor protein tyrosine kinase signaling pathways. The validation of significantly differentially expressed miRNAs in an independent set of HIV-infected (cocaine users and nondrug users) with and without PH confirmed the upregulation of miR-32-5p, 92-b-3p, and 301a-3p positively regulating cellular proliferation and downregulation of miR-5571, -4670 negatively regulating smooth muscle proliferation in EVs from HIV-PH patients. This increase in miR-301a-3p and decrease in miR-4670 were negatively correlated with the CD4 count and FEV1/FVC ratio, and positively correlated with viral load. Collectively, this data suggest the association of alterations in the miRNA cargo of circulating EVs with HIV-PH.

Endothelial Function in Pulmonary Arterial Hypertension: From Bench to Bedside

Pulmonary arterial hypertension is a complex pathology whose etiology is still not completely well clarified. The pathogenesis of pulmonary arterial hypertension involves different molecular mechanisms, with endothelial dysfunction playing a central role in disease progression. Both individual genetic predispositions and environmental factors seem to contribute to its onset. To further understand the complex relationship between endothelial and pulmonary hypertension and try to contribute to the development of future therapies, we report a comprehensive and updated review on endothelial function in pulmonary arterial hypertension.

HIV and Drug Use: A Tale of Synergy in Pulmonary Vascular Disease Development

Over the past two decades, with the advent and adoption of highly active anti-retroviral therapy, HIV-1 infection, a once fatal and acute illness, has transformed into a chronic disease with people living with HIV (PWH) experiencing increased rates of cardio-pulmonary vascular diseases including life-threatening pulmonary hypertension. Moreover, the chronic consequences of tobacco, alcohol, and drug use are increasingly seen in older PWH. Drug use, specifically, can have pathologic effects on the cardiovascular health of these individuals. The "double hit" of drug use and HIV may increase the risk of HIV-associated pulmonary arterial hypertension (HIV-PAH) and potentiate right heart failure in this population. This article explores the epidemiology and pathophysiology of PAH associated with HIV and recreational drug use and describes the proposed mechanisms by which HIV and drug use, together, can cause pulmonary vascular remodeling and cardiopulmonary hemodynamic compromise. In addition to detailing the proposed cellular and signaling pathways involved in the development of PAH, this article proposes areas ripe for future research, including the influence of gut dysbiosis and cellular senescence on the pathobiology of HIV-PAH. © 2023 American Physiological Society. Compr Physiol 13:4659-4683, 2023.

Insights into bone morphogenetic proteins in cardiovascular diseases

Bone morphogenetic proteins (BMPs) are secretory proteins belonging to the transforming growth factor-β (TGF-β) superfamily. These proteins play important roles in embryogenesis, bone morphogenesis, blood vessel remodeling and the development of various organs. In recent years, as research has progressed, BMPs have been found to be closely related to cardiovascular diseases, especially atherosclerosis, vascular calcification, cardiac remodeling, pulmonary arterial hypertension (PAH) and hereditary hemorrhagic telangiectasia (HHT). In this review, we summarized the potential roles and related mechanisms of the BMP family in the cardiovascular system and focused on atherosclerosis and PAH.

Effect of Qiling Jiaogulan Powder on Pulmonary Fibrosis and Pulmonary Arteriole Remodeling in Low-Temperature-Exposed Broilers

Chinese herbal medicine plays an important role in regulating the nutritional metabolism of poultry and maintaining or improving normal physiological functions and animal health. The present study investigated the effects of dietary supplementation with Qiling Jiaogulan Powder (QLJP) on pulmonary fibrosis and pulmonary arteriole remodeling in low temperature-exposed broilers. Seven-day-old Ross 308 broilers (n = 240) were reared adaptively to 14 days of age. The broilers were randomly divided into six groups: A control group (basal diet and normal feeding temperature); model group (basal diet); low-, medium- and high-dose QLJP groups (basal diet supplemented with 1 g/kg, 2 g/kg, 4 g/kg QLJP); and L-Arg group (basal diet supplemented with 10 g/kg L-arginine). Additionally, all the broilers, except the broilers in the control group, from the age of 14 days old, had a house temperature continuously lowered by 2 °C each day until it reached 12 °C at 21 days of age, and the low temperature was maintained until the end of the experiment. There were four replicates per group and 10 birds per replicate. The results showed that the structure of the lung tissue was clearer and basically intact in the broilers in the QLJP groups, with a small number of collagen fibers formed, and the content of hydroxyproline (HYP) was significantly reduced. QLJP improved pulmonary arteriole lesions, such as tunica media thickening, intimal hyperplasia, arterial wall hypertrophy, and lumen narrowing. QLJP reduced the relative media thickness (%) and relative medial area (%) of the pulmonary arteriole, and significantly decreased the expression level of the alpha-smooth muscle actin (α-SMA) protein in pulmonary arteriole, which alleviated pulmonary arteriole remodeling. The quantitative real-time PCR (qPCR) and enzyme-linked immunosorbent assay (ELISA) results showed that QLJP treatment significantly reduced the gene and protein levels of transforming growth factor-beta l (TGF-β1) and Smad2 in the lung and downregulated the gene and protein levels of collagen type I alpha 1 (COL1A1) and matrix metalloproteinase 2 (MMP2). In conclusion, the results of our study suggested that dietary supplementation with QLJP improved pulmonary fibrosis and pulmonary arteriole remodeling by inhibiting the expression of genes related to the TGF-β1/Smad2 signaling pathway and inhibited the occurrence and development of pulmonary arterial hypertension in low-temperature-exposed broilers.

Sotatercept analog suppresses inflammation to reverse experimental pulmonary arterial hypertension

Sotatercept is an activin receptor type IIA-Fc (ActRIIA-Fc) fusion protein that improves cardiopulmonary function in patients with pulmonary arterial hypertension (PAH) by selectively trapping activins and growth differentiation factors. However, the cellular and molecular mechanisms of ActRIIA-Fc action are incompletely understood. Here, we determined through genome-wide expression profiling that inflammatory and immune responses are prominently upregulated in the lungs of a Sugen-hypoxia rat model of severe angio-obliterative PAH, concordant with profiles observed in PAH patients. Therapeutic treatment with ActRIIA-Fc-but not with a vasodilator-strikingly reversed proinflammatory and proliferative gene expression profiles and normalized macrophage infiltration in diseased rodent lungs. Furthermore, ActRIIA-Fc normalized pulmonary macrophage infiltration and corrected cardiopulmonary structure and function in Bmpr2 haploinsufficient mice subjected to hypoxia, a model of heritable PAH. Three high-affinity ligands of ActRIIA-Fc each induced macrophage activation in vitro, and their combined immunoneutralization in PAH rats produced cardiopulmonary benefits comparable to those elicited by ActRIIA-Fc. Our results in complementary experimental and genetic models of PAH reveal therapeutic anti-inflammatory activities of ActRIIA-Fc that, together with its known anti-proliferative effects on vascular cell types, could underlie clinical activity of sotatercept as either monotherapy or add-on to current PAH therapies.

Differential bioactivity of four BMP-family members as function of biomaterial stiffness

While a soft film itself is not able to induce cell spreading, BMP-2 presented via such soft film (so called "matrix-bound BMP-2") was previously shown to trigger cell spreading, migration and downstream BMP-2 signaling. Here, we used thin films of controlled stiffness presenting matrix-bound BMPs to study the effect of four BMP members (BMP-2, 4, 7, 9) on cell adhesion and differentiation of skeletal progenitors. We performed automated high-content screening of cellular responses, including cell number, cell spreading area, SMAD phosphorylation and alkaline phosphatase activity. We revealed that the cell response to bBMPs is BMP-type specific, and involved certain BMP receptors and beta chain integrins. In addition, this response is stiffness-dependent for several receptors. The basolateral presentation of the BMPs allowed us to discriminate the specificity of cellular response, especiallyd the role of type I and II BMP receptors and of β integrins in a BMP-type and stiffness-dependent manner. Notably, BMP-2 and BMP-4 were found to have distinct roles, while ALK5, previously known as a TGF-β receptor was revealed to be involved in the BMP-pathway.

Therapeutic Approaches for Treating Pulmonary Arterial Hypertension by Correcting Imbalanced TGF-β Superfamily Signaling

Pulmonary arterial hypertension (PAH) is a rare disease characterized by high blood pressure in the pulmonary circulation driven by pathological remodeling of distal pulmonary arteries, leading typically to death by right ventricular failure. Available treatments improve physical activity and slow disease progression, but they act primarily as vasodilators and have limited effects on the biological cause of the disease—the uncontrolled proliferation of vascular endothelial and smooth muscle cells. Imbalanced signaling by the transforming growth factor-β (TGF-β) superfamily contributes extensively to dysregulated vascular cell proliferation in PAH, with overactive pro-proliferative SMAD2/3 signaling occurring alongside deficient anti-proliferative SMAD1/5/8 signaling. We review the TGF-β superfamily mechanisms underlying PAH pathogenesis, superfamily interactions with inflammation and mechanobiological forces, and therapeutic strategies under development that aim to restore SMAD signaling balance in the diseased pulmonary arterial vessels. These strategies could potentially reverse pulmonary arterial remodeling in PAH by targeting causative mechanisms and therefore hold significant promise for the PAH patient population.

The miR-182/Myadm axis regulates hypoxia-induced pulmonary hypertension by balancing the BMP- and TGF-β-signalling pathways in an SMC/EC-crosstalk-associated manner

We recently identified oncologic miR-182 as a new regulator of pulmonary artery hypertension (PAH) that targets myeloid-associated differentiation marker (Myadm), which is expressed in bone marrow stem cells and multipotent progenitors. Both miR-182 and Myadm are expressed in the cardiopulmonary system and correlated with the balance between the bone morphogenetic protein (BMP) and the transforming growth factor (TGF)-β signalling pathways, which are disturbed in PAH. We hypothesize that miR-182/Myadm are involved in BMP-TGF-β-signalling way in PAH. Hypoxia triggered pathological progression in cardiopulmonary PAH in vivo and in vitro; these changes were accompanied by strongly dowregulated BMP/SMAD1/5/8 expression and enhanced TGF-β/SMAD2/3 signalling pathway, favouring SMAD4/SMAD2 transcript formation and inhibiting the PAH negative regulator Id1 expression. miR-182 gain-of-function significantly inhibited the pathological progression in hypoxia-induced PAH (HPH) in vivo and in vitro, with a restoration of the balance in BMP-TGF-β signalling pathway. This recovery was abrogated by overexpression of Myadm. Conversely, loss-of-function of miR-182 increased the pathological progression of HPH followed by severe disturbance of BMP and TGF-β signal transduction and reduced Id1 expression, which was restored by Myadm knockdown. We also showed that the miR-182/Myadm relate BMP-TGF-β pathway is associated with NOS3/NO/cGMP via the crosstalk between endothelial cells and smooth muscle cells. Our findings further support the therapeutic significance of miR-182/Myadm in PAH via the balance of BMP- and TGF-β-associated mechanisms.

Phenotypic Diversity of Vascular Smooth Muscle Cells in Pulmonary Arterial Hypertension: Implications for Therapy

Pulmonary arterial hypertension (PAH) is a progressive incurable condition that is characterized by extensive remodelling of the pulmonary circulation, leading to severe right heart failure and death. Similar to other vascular contractile cells, pulmonary arterial smooth muscle cells (PA-SMCs) play central roles in physiological and pathological vascular remodelling due to their remarkable ability to dynamically modulate their phenotype to ensure contractile and synthetic functions. The dysfunction and molecular mechanisms underlying their contribution to the various pulmonary vascular lesions associated with PAH have been a major focus of research. The aim of this review is to describe the medial and non-medial origins of contractile cells in the pulmonary vascular wall and present evidence of how they contribute to the onset and progression of PAH. We also highlight specific potential target molecules and discuss future directions that are being explored to widen the therapeutic options for the treatment of PAH.

Notch2 Suppression Mimicking Changes in Human Pulmonary Hypertension Modulates Notch1 and Promotes Endothelial Cell Proliferation

Pulmonary arterial hypertension (PAH) is a fatal cardiopulmonary disease characterized by increased vascular cell proliferation with resistance to apoptosis and occlusive remodeling of the small pulmonary arteries in humans. The Notch family of proteins are proximal signaling mediators of an evolutionarily conserved pathway that effect cell proliferation, fate determination, and development. In endothelial cells (ECs), Notch receptor 2 (Notch2) has been shown to promote endothelial apoptosis. However, a pro- or anti-proliferative role for Notch2 in pulmonary endothelial proliferation and ensuing PAH is unknown. Herein, we postulated that suppressed Notch2 signaling drives pulmonary endothelial proliferation in the setting of PAH. We observed that levels of Notch2 are ablated in lung and PA tissue samples from PAH patients compared to non-PAH controls. Interestingly, Notch2 expression was attenuated in human pulmonary artery endothelial cells (hPAECs) exposed to vasoactive factors including hypoxia, TGFβ, ET-1, and IGF-1. Gene silencing of Notch2 increased EC proliferation and reduced apoptosis. At the molecular level, Notch2-deficient hPAECs activated Akt, Erk1/2 and anti-apoptotic protein Bcl-2, and reduced levels of p21^cip and Bax. Intriguingly, loss of Notch2 elicits a paradoxical activation of Notch1 and transcriptional upregulation of canonical Notch target genes Hes1, Hey1 and Hey2. Further, reduction in Rb and increased E2F1 binding to the Notch1 promoter appear to explain the upregulation of Notch1. In aggregate, our results demonstrate that loss of Notch2 derepresses Notch1 and elicits aberrant EC hallmarks of PAH. The data underscore a novel role for Notch in the maintenance of endothelial cell homeostasis.

Cyanidin‑3‑O‑β‑glucoside protects against pulmonary artery hypertension induced by monocrotaline via the TGF‑β1/p38 MAPK/CREB signaling pathway

Pulmonary artery hypertension (PAH) is a disease with high morbidity and mortality. Cyanidin‑3‑O‑β‑glucoside (Cy‑3‑g), a classical anthocyanin, has a variety of biological effects. The present study evaluated whether Cy‑3‑g attenuated PAH, and explored the potential mechanism of action. Rats were injected with monocrotaline (MCT; 60 mg per kg of body weight) and then treated with Cy‑3‑g (200 or 400 mg per kg of body weight) for 4 weeks. Protein expression was determined in vitro in transforming growth factor‑β1 (TGF‑β1)‑mediated human pulmonary arterial smooth muscle cells (SMCs). The results indicated that Cy‑3‑g significantly inhibited the mean pulmonary artery pressure, right ventricular systolic pressure and right ventricular hypertrophy index, as well as vascular remodeling induced by MCT in PAH rats. Further experiments showed that Cy‑3‑g suppressed the expression of pro‑-inflammatory factors and enhanced the levels of anti‑inflammatory factors. Cy‑3‑g blocked oxidative stress and improved vascular endothelial injury. Cy‑3‑g also reduced the proliferation of SMCs. Furthermore, the MCT‑ and TGF‑β1‑induced increase in TGF‑β1, phosphorylated (p)‑p38 mitogen‑activated protein kinase (MAPK) and p‑cAMP‑response element binding protein (CREB) expression was blocked by Cy‑3‑g treatment in vivo and in vitro. These results indicated that Cy‑3‑g could prevent vascular remodeling in PAH via inhibition of the TGF‑β1/p38 MAPK/CREB axis.

Icariin Attenuates Monocrotaline-Induced Pulmonary Arterial Hypertension via the Inhibition of TGF-β1/Smads Pathway in Rats

Background

Pulmonary artery remodeling is important in the development of pulmonary artery hypertension. The TGF-β1/Smads signaling pathway is activated in pulmonary arterial hypertension (PAH) in rats. Icariin (ICA) suppresses the TGF-β1/Smad2 pathway in myocardial fibrosis in rats. Therefore, we investigated the role of icariin in PAH by inhibiting the TGF-β1/Smads pathway.

Methods

Rats were randomly divided into control, monocrotaline (MCT), MCT + ICA-low, and MCT + ICA-high groups. MCT (60 mg/kg) was subcutaneously injected to induce PAH, and icariin (50 or 100 mg/kg.d) was orally administered for 2 weeks. At the end of the fourth week, right ventricular systolic pressure (RVSP) was obtained and the right ventricular hypertrophy index (RI) was determined as the ratio of the right ventricular weight to the left ventricular plus septal weight (RV/LV + S). Western blots were used to determine the expression of TGF-β1, Smad2/3, P-Smad2/3, and matrix metalloproteinase-2 (MMP2) in lung tissues.

Results

Compared to the control group, RVSP and RI were increased in the MCT group (ρ < 0.05). Additionally, TGF-β1, Smad2/3, P-Smad2/3, and MMP2 expressions were obviously increased (ρ < 0.01). Compared to the MCT group, RVSP and RI were decreased in the MCT + ICA group (ρ < 0.05). TGF-β1, Smad2/3, P-Smad2/3, and MMP2 expressions were also inhibited in the icariin treatment groups (ρ < 0.05). Conclusions. Icariin may suppress MCT-induced PAH via the inhibition of the TGFβ1-Smad2/3 pathway.

Dual roles of TGF-β signaling in the regulation of dental epithelial cell proliferation

The purpose of this study is to investigate the molecular mechanisms and biological function of TGF-β-activated Smad1/5 in dental epithelium. Immunohistochemistry was used to detect the expressions of TGF-β signaling-related gene in mice molar germ. Primary dental epithelial cells were cultured and treated with TGF-β1 at a concentration of 0.5 or 5 ng/mL. Small molecular inhibitors, SB431542 and ML347, was used to inhibite ALK5 and ALK1/2, respectively. Small interfering RNA was used to knock down Smad1/5 or Smad2/3. The proliferation rate of cells was evaluated by EdU assay. In the basal layer of dental epithelial bud TGF-β1 and p-Smad1/5 were highly expressed, and in the interior of the epithelial bud TGF-β1 was lowly expressed, whereas p-Smad2/3 was highly expressed. In primary cultured dental epithelial cells, low concentration of TGF-β1 activated Smad2/3 but not Smad1/5, while high concentration of TGF-β1 was able to activate both Smad2/3 and Smad1/5. SB431542 but not ML347 was able to block the phosphorylation of Smad2/3 by TGF-β1. Either SB431542 or ML347 was able to block the phosphorylation of Smad1/5 by TGF-β1. EdU staining showed that high concentration of TGF-β1 promoted dental epithelial cell proliferation, which was reversed by silencing Smad1/5, whereas low concentration of TGF-β1 inhibited cell proliferation, which was reversed by silencing Smad2/3. In conclusions, TGF-β exhibits dual roles in the regulation of dental epithelial cell proliferation through two pathways. On the one hand, TGF-β activates canonical Smad2/3 signaling through ALK5, inhibiting the proliferation of internal dental epithelial cells. On the other hand, TGF-β activates noncanonical Smad1/5 signaling through ALK1/2-ALK5, promoting the proliferation of basal cells in the dental epithelial bud.

Network medicine in Cardiovascular Research

The ability to generate multi-omics data coupled with deeply characterizing the clinical phenotype of individual patients promises to improve understanding of complex cardiovascular pathobiology. There remains an important disconnection between the magnitude and granularity of these data and our ability to improve phenotype-genotype correlations for complex cardiovascular diseases. This shortcoming may be due to limitations associated with traditional reductionist analytical methods, which tend to emphasize a single molecular event in the pathogenesis of diseases more aptly characterized by crosstalk between overlapping molecular pathways. Network medicine is a rapidly growing discipline that considers diseases as the consequences of perturbed interactions between multiple interconnected biological components. This powerful integrative approach has enabled a number of important discoveries in complex disease mechanisms. In this review, we introduce the basic concepts of network medicine and highlight specific examples by which this approach has accelerated cardiovascular research. We also review how network medicine is well-positioned to promote rational drug design for patients with cardiovascular diseases, with particular emphasis on advancing precision medicine.

Opposing and potentially antagonistic effects of BMP and TGF-β in multiple sclerosis: The "Yin and Yang" of neuro-immune Signaling

Bone Morphogenetic Proteins (BMP) and Transforming Growth Factor-beta (TGF-β) are cytokines with similar receptors and messengers. They are important for immune cell function, with BMPs exerting mainly proinflammatory but also anti-inflammatory effects, and TGF-β suppressing inflammation. Patients with Multiple Sclerosis exhibit BMP overactivity and suppressed TGF-β signaling. This dysregulated signaling participates in the crosstalk between infiltrating immune cells and glia, where BMP inhibits remyelination. Reciprocal antagonism between the two pathways takes place via a variety of mechanisms. Although this antagonism has not been studied in the setting of Multiple Sclerosis, it could inform further research and treatment discovery.

SIRT1 promotes pulmonary artery endothelial cell proliferation by targeting the Akt signaling pathway

Pulmonary arterial hypertension (PAH) is a disease characterized by a progressive increase in pulmonary vascular resistance and obliterative pulmonary vascular remodeling; however, the pathogenesis of the disease is not completely understood. Sirtuin 1 (SIRT1) is a histone deacetylase involved in cell survival and metabolism. The present study explored the potential role of SIRT1 in human pulmonary arterial endothelial cells (HPAECs) under hypoxic conditions. In vitro HPAECs were cultured and exposed to hypoxic conditions. Subsequently, SIRT1 expression levels were measured via western blotting, the generation of reactive oxygen species (ROS) was evaluated, and the interaction between SIRT1 and Akt was assessed via reverse transcription-quantitative PCR and western blotting. In addition, the effects of SIRT1 on cell proliferation and apoptosis were also investigated. The results indicated that hypoxia induced SIRT1 expression in pulmonary arterial endothelial cells, which may be associated with ROS generation. SIRT1 expression activated the Akt signaling pathway, which increased the expression levels of Bcl-2 and hypoxia-inducible factor-1 in HPAECs. Moreover, SIRT1 promoted HPAEC proliferation and inhibited HPAEC apoptosis. ROS generation enhanced the SIRT1/Akt axis, which was essential for epithelial cell injury under hypoxic conditions. Therefore, blocking SIRT1 may reduce hypoxia-induced pathological damage in HPAECs.

The application of big data to cardiovascular disease: paths to precision medicine

Advanced phenotyping of cardiovascular diseases has evolved with the application of high-resolution omics screening to populations enrolled in large-scale observational and clinical trials. This strategy has revealed that considerable heterogeneity exists at the genotype, endophenotype, and clinical phenotype levels in cardiovascular diseases, a feature of the most common diseases that has not been elucidated by conventional reductionism. In this discussion, we address genomic context and (endo)phenotypic heterogeneity, and examine commonly encountered cardiovascular diseases to illustrate the genotypic underpinnings of (endo)phenotypic diversity. We highlight the existing challenges in cardiovascular disease genotyping and phenotyping that can be addressed by the integration of big data and interpreted using novel analytical methodologies (network analysis). Precision cardiovascular medicine will only be broadly applied to cardiovascular patients once this comprehensive data set is subjected to unique, integrative analytical strategies that accommodate molecular and clinical heterogeneity rather than ignore or reduce it.

TGF-β1 increases sialidase 3 expression in human lung epithelial cells by decreasing its degradation and upregulating its translation

Purpose: We previously found extensive desialylation of glycoconjugates and upregulation of the sialidase enzyme NEU3 in fibrotic lesions in human and mouse lungs. However, studies using microarray analysis of whole lung tissue mRNA and single cell RNA-seq found no significant difference in levels of NEU3 mRNA between IPF patients and controls. This study aimed to elucidate how NEU3 was upregulated in fibrotic lungs.Materials and methods: Transforming growth factor-β1 (TGF-β1), a key driver of fibrosis, was added to A549 human alveolar basal epithelial adenocarcinoma cells and human small airway epithelial cells (HSAEpC). NEU3 expression in A549 cells and HSAEpC was detected by immunofluorescence staining. NEU3 translation and degradation were assessed by polysome profiling (polysomes efficiently translate mRNAs; monosomes poorly translate mRNAs) and cycloheximide chase after treating cells with or without TGF-β1 for 48 h.Results: TGF-β1 increased NEU3 expression and secretion in A549 cells and HSAEpC but did not change total (nuclear + cytosolic) NEU3 mRNA levels. TGF-β1 decreased the degradation rate of NEU3 in A549 cells. TGF-β1 decreased NEU3 mRNA levels in monosomes and increased NEU3 mRNA level in polysomes.Conclusion: TGF-β1 upregulates levels of NEU3 in epithelial cells by both decreasing NEU3 degradation and by increasing the translation of NEU3 mRNA, explaining the apparent paradox of high levels of NEU3 protein in pulmonary fibrosis without a concomitant increase in the expression of NEU3 mRNA.

Opposing roles and potential antagonistic mechanism between TGF-β and BMP pathways: Implications for cancer progression

The transforming growth factor β (TGF-β) superfamily participates in tumour proliferation, apoptosis, differentiation, migration, invasion, immune evasion and extracellular matrix remodelling. Genetic deficiency in distinct components of TGF-β and BMP-induced signalling pathways or their excessive activation has been reported to regulate the development and progression of some cancers. As more in-depth studies about this superfamily have been conducted, more evidence suggests that the TGF-β and BMP pathways play an opposing role. The cross-talk of these 2 pathways has been widely studied in kidney disease and bone formation, and the opposing effects have also been observed in some cancers. However, the antagonistic mechanisms are still insufficiently investigated in cancer. In this review, we aim to display more evidences and possible mechanisms accounting for the antagonism between these 2 pathways, which might provide some clues for further study in cancer.

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Describe the basics of TGF-β and BMP signalling

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Summarize the potential mechanisms accounting for the antagonism between TGF-β and BMP pathways

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Provide some evidence about the antagonistic effects between pathways observed in some cancers

Drug abuse and HIV-related pulmonary hypertension: double hit injury

: Improved survival among HIV-1-infected individuals with the advent of antiretroviral therapy has clearly led to a greater prevalence of noninfectious complications. One of the most devastating sequelae in these individuals is the development of pulmonary arterial hypertension (PAH). Various epidemiological studies suggest worse survival of HIV-PAH patients when compared with other forms of PAH. Given that only a subset and not all HIV-infected individuals develop HIV-PAH, it is suggested that an additional second-hit of genetic or environmental trigger is needed for the development of PAH. In this context, it has been well documented that HIV patients who abuse illicit drugs such as stimulants, opioids, and the like, are more susceptible to develop PAH. In this review, we highlight the studies that support the significance of a double hit of HIV and drug abuse in the incidence of PAH and focus on the research that has been undertaken to unravel the pathobiology and vascular remodeling mechanisms underlying the deleterious synergy between HIV infection and drugs of abuse in orchestrating the development of PAH.

Treatment with low-dose tacrolimus inhibits bleeding complications in a patient with hereditary hemorrhagic telangiectasia and pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) can be found in patients suffering from a loss-of-function mutation of the gene encoding for the activin receptor-like kinase 1 (ALK-1), a bone morphogenetic protein (BMP) type 1 receptor. Interestingly, ALK-1 mutations also lead to hereditary hemorrhagic telangiectasia (HHT), an autosomal dominant disease characterized by arteriovenous malformations (AVMs) leading to potentially life-threatening bleeding complications such as epistaxis. Current therapeutic options for both diseases are limited and often only temporary or accompanied by severe side effects. Here, we report of a patient with a mutation of the ALK-1 gene suffering from both HHT and PAH. Recently, it was shown that tacrolimus increased ALK-1 signaling and had beneficial effects in selected end-stage PAH patients. We thus hypothesized that treatment with tacrolimus may prevent disease progression in this patient. Surprisingly, treatment with low-dose tacrolimus dramatically improved his HHT-associated epistaxis but did not attenuate progression of PAH.

TGF-β and BMPR2 Signaling in PAH: Two Black Sheep in One Family

Knowledge pertaining to the involvement of transforming growth factor β (TGF-β) and bone morphogenetic protein (BMP) signaling in pulmonary arterial hypertension (PAH) is continuously increasing. There is a growing understanding of the function of individual components involved in the pathway, but a clear synthesis of how these interact in PAH is currently lacking. Most of the focus has been on signaling downstream of BMPR2, but it is imperative to include the role of TGF-β signaling in PAH. This review gives a state of the art overview of disturbed signaling through the receptors of the TGF-β family with respect to vascular remodeling and cardiac effects as observed in PAH. Recent (pre)-clinical studies in which these two pathways were targeted will be discussed with an extended view on cardiovascular research fields outside of PAH, indicating novel future perspectives.

Consequences of BMPR2 Deficiency in the Pulmonary Vasculature and Beyond: Contributions to Pulmonary Arterial Hypertension

Since its association with familial pulmonary arterial hypertension (PAH) in 2000, Bone Morphogenetic Protein Receptor II (BMPR2) and its related signaling pathway have become recognized as a key regulator of pulmonary vascular homeostasis. Herein, we define BMPR2 deficiency as either an inactivation of the receptor, decreased receptor expression, or an impairment of the receptor’s downstream signaling pathway. Although traditionally the phenotypic consequences of BMPR2 deficiency in PAH have been thought to be limited to the pulmonary vasculature, there is evidence that abnormalities in BMPR2 signaling may have consequences in many other organ systems and cellular compartments. Revisiting how BMPR2 functions throughout health and disease in cells and organs beyond the lung vasculature may provide insight into the contribution of these organ systems to PAH pathogenesis as well as the potential systemic manifestation of PAH. Here we review our knowledge of the consequences of BMPR2 deficiency across multiple organ systems.

NEDD9 targets COL3A1 to promote endothelial fibrosis and pulmonary arterial hypertension

Germline mutations involving small mothers against decapentaplegic-transforming growth factor-β (SMAD-TGF-β) signaling are an important but rare cause of pulmonary arterial hypertension (PAH), which is a disease characterized, in part, by vascular fibrosis and hyperaldosteronism (ALDO). We developed and analyzed a fibrosis protein-protein network (fibrosome) in silico, which predicted that the SMAD3 target neural precursor cell expressed developmentally down-regulated 9 (NEDD9) is a critical ALDO-regulated node underpinning pathogenic vascular fibrosis. Bioinformatics and microscale thermophoresis demonstrated that oxidation of Cys18 in the SMAD3 docking region of NEDD9 impairs SMAD3-NEDD9 protein-protein interactions in vitro. This effect was reproduced by ALDO-induced oxidant stress in cultured human pulmonary artery endothelial cells (HPAECs), resulting in impaired NEDD9 proteolytic degradation, increased NEDD9 complex formation with Nk2 homeobox 5 (NKX2-5), and increased NKX2-5 binding to COL3A1 Up-regulation of NEDD9-dependent collagen III expression corresponded to changes in cell stiffness measured by atomic force microscopy. HPAEC-derived exosomal signaling targeted NEDD9 to increase collagen I/III expression in human pulmonary artery smooth muscle cells, identifying a second endothelial mechanism regulating vascular fibrosis. ALDO-NEDD9 signaling was not affected by treatment with a TGF-β ligand trap and, thus, was not contingent on TGF-β signaling. Colocalization of NEDD9 with collagen III in HPAECs was observed in fibrotic pulmonary arterioles from PAH patients. Furthermore, NEDD9 ablation or inhibition prevented fibrotic vascular remodeling and pulmonary hypertension in animal models of PAH in vivo. These data identify a critical TGF-β-independent posttranslational modification that impairs SMAD3-NEDD9 binding in HPAECs to modulate vascular fibrosis and promote PAH.

MiR-125a-5p ameliorates monocrotaline-induced pulmonary arterial hypertension by targeting the TGF-β1 and IL-6/STAT3 signaling pathways

Pulmonary vascular remodeling due to excessive proliferation and resistance to apoptosis of pulmonary artery smooth muscle cells (PASMCs) is the hallmark feature of pulmonary arterial hypertension (PAH). Recent evidence suggests that miR-125a-5p plays a role in a rat model of monocrotaline-induced PAH (MCT-PAH); however, the underlying mechanism is currently unknown. Here, we examined the expression profile of miR-125a-5p in MCT-PAH rats and investigated the putative therapeutic effect of miR-125a-5p using the miR-125a-5p agomir. In addition, the miR-125a-5p agomir or antagomir was transfected into rat PASMCs, and proliferation and apoptosis were measured. Activity of the miR-125a-5p target STAT3 was measured using a luciferase reporter assay, and the expression of downstream molecules was measured using RT–qPCR and/or western blot analysis. Importantly, inducing miR-125a-5p expression in vivo slowed the progression of MCT-PAH by reducing systolic pulmonary arterial pressure, the Fulton index, and pulmonary vascular remodeling. Moreover, overexpressing miR-125a-5p inhibited the proliferation and promoted the apoptosis of PASMCs. In addition, stimulating PASMCs with TGF-β1 or IL-6 upregulated miR-125a-5p expression, whereas overexpressing miR-125a-5p reduced TGF-β1 and IL-6 production, as well as the expression of their downstream targets STAT3 and Smad2/3; in contrast, downregulating miR-125a-5p increased TGF-β1 and IL-6 production. Finally, a dual-luciferase reporter assay revealed that miR-125a-5p targets the 3′-UTR of STAT3, suppressing the downstream molecules PCNA, Bcl-2, and Survivin. Taken together, these findings suggest that miR-125a-5p ameliorates MCT-PAH in rats, has a negative feedback regulation with TGF-β1 and IL-6, and regulates the proliferation and apoptosis of PASMCs by directly targeting STAT3.

A study in rats suggests that the small RNA molecule miR-125a-5p is a promising therapeutic target for treating pulmonary arterial hypertension (PAH). This type of high blood pressure is due to the narrowing of arteries that carry blood from the heart to the lungs and at present has no cure. Jieyan Shen at Shanghai Jiao Tong University, China, and colleagues found that PAH lowers the levels of miR-125a-5p in rat pulmonary arteries and that administration of miR-125a-5p as an early preventative treatment reduced disease progression. miR-125a-5p slowed the proliferation of pulmonary artery smooth muscle cells and triggered cell death by directly interacting with a gene expression regulator and reducing the production of certain pro-inflammatory signaling molecules. Targeting miR-125a-5p’s mechanism of action could represent a new treatment approach for this chronic, life-changing disease.

Clinical Relevance and Mechanisms of Antagonism Between the BMP and Activin/TGF-β Signaling Pathways

The transforming growth factor β (TGF-β) superfamily is a large group of signaling molecules that participate in embryogenesis, organogenesis, and tissue homeostasis. These molecules are present in all animal genomes. Dysfunction in the regulation or activity of this superfamily's components underlies numerous human diseases and developmental defects. There are 2 distinct arms downstream of the TGF-β superfamily ligands-the bone morphogenetic protein (BMP) and activin/TGF-β signaling pathways-and these 2 responses can oppose one another's effects, most notably in disease states. However, studies have commonly focused on a single arm of the TGF-β superfamily, and the antagonism between these pathways is unknown in most physiologic and pathologic contexts. In this review, the authors summarize the clinically relevant scenarios in which the BMP and activin/TGF-β pathways reportedly oppose one another and identify several molecular mechanisms proposed to mediate this interaction. Particular attention is paid to experimental findings that may be informative to human pathology to highlight potential therapeutic approaches for future investigation.

Hyperactive TGF-β Signaling in Smooth Muscle Cells Exposed to HIV-protein(s) and Cocaine: Role in Pulmonary Vasculopathy

We earlier demonstrated synergistic increase in the proliferation of pulmonary smooth muscle cells on exposure to HIV-proteins and/or cocaine due to severe down-modulation of bone morphogenetic protein receptor (BMPR) axis: the anti-proliferative arm of TGF-β super family of receptors. Here, now we demonstrate the effect of HIV-Tat and cocaine on the proliferative TGF-β signaling cascade. We observed a significant increase in the secretion of TGF-β1 ligand along with enhanced protein expression of TGFβ Receptor (TGFβR)-1, TGFβR-2 and phosphorylated SMAD2/3 in human pulmonary arterial smooth muscle cells on treatment with cocaine and Tat. Further, we noticed an increase in the levels of p-TAK1 complexed with TGFβR-2. Concomitant to this a significant increase in the activation of TAK1-mediated, SMAD-independent downstream signaling molecules: p-MKK4 and p-JNK was observed. However, activation of MKK3/6-p38MAPK, another axis downstream of TAK1 was found to be reduced due to attenuation in the protein levels of BMPR2. Both SMAD and non-SMAD dependent TGFβR cascades were found to contribute to hyper-proliferation. Finally the increase in the levels of phosphorylated TGFβR1 and TGFβR2 on exposure to HIV-proteins and cocaine was confirmed in pulmonary smooth muscle cells from cocaine injected HIV-transgenic rats and in total lung extracts from HIV infected cocaine and/or opioid users.

Transforming growth factor-β stimulates Smad1/5 signaling in pulmonary artery smooth muscle cells and fibroblasts of the newborn mouse through ALK1

The intracellular signaling mechanisms through which TGF-β regulates pulmonary development are incompletely understood. Canonical TGF-β signaling involves Smad2/3 phosphorylation, Smad2/3·Smad4 complex formation and nuclear localization, and gene regulation. Here, we show that physiologically relevant TGF-β1 levels also stimulate Smad1/5 phosphorylation, which is typically a mediator of bone morphogenetic protein (BMP) signaling, in mouse pup pulmonary artery smooth muscle cells (mPASMC) and lung fibroblasts and other interstitial lung cell lines. This cross-talk mechanism likely has in vivo relevance because mixed Smad1/5/8·Smad2/3 complexes, which are indicative of TGF-β-stimulated Smad1/5 activation, were detected in the developing mouse lung using a proximity ligation assay. Although mixed Smad complexes have been shown not to transduce nuclear signaling, we determined that TGF-β stimulates nuclear localization of phosphorylated Smad1/5 and induces the expression of prototypical BMP-regulated genes in the mPASMC. Small-molecule kinase inhibitor studies suggested that TGF-β-regulated Smad1/5 phosphorylation in these cells is mediated by TGF-β-type I receptors, not BMP-type I receptors, but possibly the accessory activin-like kinase (ALK1) receptor. Although work by others suggested that ALK1 is expressed exclusively in endothelial cells in the vasculature, we detected ALK1 mRNA and protein expression in mPASMC in vitro and in mouse pup lungs. Moreover, using an antimurine ALK1 antibody and mPASMC, we determined that ALK1 regulates Smad1/5 phosphorylation by TGF-β. Together, these studies characterize an accessory TGF-β-stimulated BMP R-Smad signaling mechanism in interstitial cells of the developing lung. They also indicate the importance of considering alternate Smad pathways in studies directed at determining how TGF-β regulates newborn lung development.

Codependence of Bone Morphogenetic Protein Receptor 2 and Transforming Growth Factor-β in Elastic Fiber Assembly and Its Perturbation in Pulmonary Arterial Hypertension

OBJECTIVE

We determined in patients with pulmonary arterial (PA) hypertension (PAH) whether in addition to increased production of elastase by PA smooth muscle cells previously reported, PA elastic fibers are susceptible to degradation because of their abnormal assembly.

APPROACH AND RESULTS

Fibrillin-1 and elastin are the major components of elastic fibers, and fibrillin-1 binds bone morphogenetic proteins (BMPs) and the large latent complex of transforming growth factor-β1 (TGFβ1). Thus, we considered whether BMPs like TGFβ1 contribute to elastic fiber assembly and whether this process is perturbed in PAH particularly when the BMP receptor, BMPR2, is mutant. We also assessed whether in mice with Bmpr2/1a compound heterozygosity, elastic fibers are susceptible to degradation. In PA smooth muscle cells and adventitial fibroblasts, TGFβ1 increased elastin mRNA, but the elevation in elastin protein was dependent on BMPR2; TGFβ1 and BMP4, via BMPR2, increased extracellular accumulation of fibrillin-1. Both BMP4- and TGFβ1-stimulated elastic fiber assembly was impaired in idiopathic (I) PAH-PA adventitial fibroblast versus control cells, particularly those with hereditary (H) PAH and a BMPR2 mutation. This was related to profound reductions in elastin and fibrillin-1 mRNA. Elastin protein was increased in IPAH PA adventitial fibroblast by TGFβ1 but only minimally so in BMPR2 mutant cells. Fibrillin-1 protein increased only modestly in IPAH or HPAH PA adventitial fibroblasts stimulated with BMP4 or TGFβ1. In Bmpr2/1a heterozygote mice, reduced PA fibrillin-1 was associated with elastic fiber susceptibility to degradation and more severe pulmonary hypertension.

CONCLUSIONS

Disrupting BMPR2 impairs TGFβ1- and BMP4-mediated elastic fiber assembly and is of pathophysiologic significance in PAH.

Schisandrin B displays a protective role against primary pulmonary hypertension by targeting transforming growth factor β1

Pulmonary arterial smooth muscle cells (PASMCs) in the medial layer of the vessel wall are involved in vessel homeostasis, but also for pathologic vascular remodeling in diverse diseases, such as pulmonary arterial hypertension (PAH). Pulmonary vascular remodeling in PAH results in vascular disorders, but its underlying molecular mechanisms are still not to be fully disclosed. In this study, we investigated the expression and function of the transforming growth factor (TGF)-β1 in human PASMC cultured under the condition of hypoxia and elucidated the effect of schisandra chinensis and its active ingredients on proliferation, migration, and apoptosis in human PASMCs. We demonstrated that schisandrin B (Sch.B) alleviated the severity of PAH in PASMCs cultured under the condition of hypoxia. Significant upregulation of TGF-β1 was observed in hypoxia-induced human PASMCs. Interestingly, administration of Sch.B substantially attenuated TGF-β1 level in these PASMCs. In order to elucidate Sch.B function, the hypoxia-induced human PASMC was stimulated with Sch.B or cotreatment with TGF-β1 in vitro. In agreement with its TGF-β1-reducing effect, Sch B relieved human PASMCs migration and promoted the apoptosis of human PASMCs, by activation of TGF-β1 downstream signal pathways in PASMCs. In contrast, co-treatment with TGF-β1 promoted human PASMC proliferation and migration and inhibited the apoptosis of human PASMC, which can attenuate the protective role of Sch.B in human PASMC. Taken collectively, these findings suggest that the vascular relaxation evoked by Sch.B was mediated by direct effect on vascular smooth muscle cell via TGF-β1 downstream signal pathways.

Wdr68 Mediates Dorsal and Ventral Patterning Events for Craniofacial Development

Birth defects are among the leading causes of infant mortality and contribute substantially to illness and long-term disability. Defects in Bone Morphogenetic Protein (BMP) signaling are associated with cleft lip/palate. Many craniofacial syndromes are caused by defects in signaling pathways that pattern the cranial neural crest cells (CNCCs) along the dorsal-ventral axis. For example, auriculocondylar syndrome is caused by impaired Endothelin-1 (Edn1) signaling, and Alagille syndrome is caused by defects in Jagged-Notch signaling. The BMP, Edn1, and Jag1b pathways intersect because BMP signaling is required for ventral edn1 expression that, in turn, restricts jag1b to dorsal CNCC territory. In zebrafish, the scaffolding protein Wdr68 is required for edn1 expression and subsequent formation of the ventral Meckel’s cartilage as well as the dorsal Palatoquadrate. Here we report that wdr68 activity is required between the 17-somites and prim-5 stages, that edn1 functions downstream of wdr68, and that wdr68 activity restricts jag1b, hey1, and grem2 expression from ventral CNCC territory. Expression of dlx1a and dlx2a was also severely reduced in anterior dorsal and ventral 1^st arch CNCC territory in wdr68 mutants. We also found that the BMP agonist isoliquiritigenin (ISL) can partially rescue lower jaw formation and edn1 expression in wdr68 mutants. However, we found no significant defects in BMP reporter induction or pSmad1/5 accumulation in wdr68 mutant cells or zebrafish. The Transforming Growth Factor Beta (TGF-β) signaling pathway is also known to be important for craniofacial development and can interfere with BMP signaling. Here we further report that TGF-β interference with BMP signaling was greater in wdr68 mutant cells relative to control cells. To determine whether interference might also act in vivo, we treated wdr68 mutant zebrafish embryos with the TGF-β signaling inhibitor SB431542 and found partial rescue of edn1 expression and craniofacial development. While ISL treatment failed, SB431542 partially rescued dlx2a expression in wdr68 mutants. Together these findings reveal an indirect role for Wdr68 in the BMP-Edn1-Jag1b signaling hierarchy and dorso-anterior expression of dlx1a/2a.

Developmental Reprogramming in Mesenchymal Stromal Cells of Human Subjects with Idiopathic Pulmonary Fibrosis

Cellular plasticity and de-differentiation are hallmarks of tissue/organ regenerative capacity in diverse species. Despite a more restricted capacity for regeneration, humans with age-related chronic diseases, such as cancer and fibrosis, show evidence of a recapitulation of developmental gene programs. We have previously identified a resident population of mesenchymal stromal cells (MSCs) in the terminal airways-alveoli by bronchoalveolar lavage (BAL) of human adult lungs. In this study, we characterized MSCs from BAL of patients with stable and progressive idiopathic pulmonary fibrosis (IPF), defined as <5% and ≥10% decline, respectively, in forced vital capacity over the preceding 6-month period. Gene expression profiles of MSCs from IPF subjects with progressive disease were enriched for genes regulating lung development. Most notably, genes regulating early tissue patterning and branching morphogenesis were differentially regulated. Network interactive modeling of a set of these genes indicated central roles for TGF-β and SHH signaling. Importantly, fibroblast growth factor-10 (FGF-10) was markedly suppressed in IPF subjects with progressive disease, and both TGF-β1 and SHH signaling were identified as critical mediators of this effect in MSCs. These findings support the concept of developmental gene re-activation in IPF, and FGF-10 deficiency as a potentially critical factor in disease progression.

The expression of Smad signaling pathway in myocardium and potential therapeutic effects

Myocardial infarction (MI) is a life-threatening disease. The expression of Smad proteins in the ischemic myocardium changes significantly following myocardial infarction, suggesting a close relationship between Smad proteins and heart remodeling. Moreover, it is known that the expression of Smads is regulated by transforming growth factor-β (TGF-β) and bone morphogenetic proteins (BMP). Based on these findings, regulating the expression of Smad proteins by targeting TGF-β and BMP in the ischemic myocardium may be considered to be a possible therapeutic strategy for the treatment of myocardial infarction.

Transcriptome and proteome characterization of surface ectoderm cells differentiated from human iPSCs

Surface ectoderm (SE) cells give rise to structures including the epidermis and ectodermal associated appendages such as hair, eye, and the mammary gland. In this study, we validate a protocol that utilizes BMP4 and the γ-secretase inhibitor DAPT to induce SE differentiation from human induced pluripotent stem cells (hiPSCs). hiPSC-differentiated SE cells expressed markers suggesting their commitment to the SE lineage. Computational analyses using integrated quantitative transcriptomic and proteomic profiling reveal that TGFβ superfamily signaling pathways are preferentially activated in SE cells compared with hiPSCs. SE differentiation can be enhanced by selectively blocking TGFβ-RI signaling. We also show that SE cells and neural ectoderm cells possess distinct gene expression patterns and signaling networks as indicated by functional Ingenuity Pathway Analysis. Our findings advance current understanding of early human SE cell development and pave the way for modeling of SE-derived tissue development, studying disease pathogenesis, and development of regenerative medicine approaches.

Identification of multiple ACVRL1 mutations in patients with pulmonary arterial hypertension by targeted exome capture

Pulmonary artery hypertension (PAH) is characterized as sustained elevation of pressure in the pulmonary vascular system that is attributable to a variety of causes. More than a dozen genes have previously been proposed as being associated with PAH. To examine potential mutations of these genes in patients with PAH, we developed a targeted exome kit containing 22 PAH-associated genes for genetic screens of 80 unrelated patients with PAH. As a result, we identified 16 different mutations in the BMPR2 gene and four different mutations in ACVRL1, the gene for activin receptor-like kinase-1 (ACVRL1). However, no deleterious mutations were found in the remaining 20 genes. In the present study, we provided detailed characterization of the ACVRL1 mutations in four pedigrees, including two novel missense mutations (c.676G>A, p.V226M; c.955G>C, p.G319R) and two recurrent mutations (c.1231C>T, p.R411W; c.1450C>T, p.R484W). Furthermore, we showed that markedly reduced Smad1/5 phosphorylation levels and reduced activities of luciferase reporters in each of the four ACVRL1 mutant-transfected NIH-3T3 cells. Therefore, our findings demonstrated that missense mutations of ACVRL1 identified in the present study significantly affected the bone morphogenetic protein 9 (BMP-9) pathway, implicating PAH pathogenesis. Detailed genotype–phenotype correlation analysis revealed initial symptoms of hereditary haemorrhagic telangiectasia (HHT) in some of the patients, suggesting the importance of sequencing molecular markers for early identification and intervention of individuals at risk for PAH and potential HHT. We developed a customized exome sequencing system to identify mutations in these PAH-associated genes, and found two novel missense mutations and two recurrent mutations in the ACVRL1 gene in four unrelated Chinese families; we also determined hypomorphic alleles using functional studies.

Salvianolic acid A attenuates vascular remodeling in a pulmonary arterial hypertension rat model

AIM

The current therapeutic approaches have a limited effect on the dysregulated pulmonary vascular remodeling, which is characteristic of pulmonary arterial hypertension (PAH). In this study we examined whether salvianolic acid A (SAA) extracted from the traditional Chinese medicine 'Dan Shen' attenuated vascular remodeling in a PAH rat model, and elucidated the underlying mechanisms.

METHODS

PAH was induced in rats by injecting a single dose of monocrotaline (MCT 60 mg/kg, sc). The rats were orally treated with either SAA (0.3, 1, 3 mg·kg(-1)·d(-1)) or a positive control bosentan (30 mg·kg(-1)·d(-1)) for 4 weeks. Echocardiography and hemodynamic measurements were performed on d 28. Then the hearts and lungs were harvested, the organ indices and pulmonary artery wall thickness were calculated, and biochemical and histochemical analysis were conducted. The levels of apoptotic and signaling proteins in the lungs were measured using immunoblotting.

RESULTS

Treatment with SAA or bosentan effectively ameliorated MCT-induced pulmonary artery remodeling, pulmonary hemodynamic abnormalities and the subsequent increases of right ventricular systolic pressure (RVSP). Furthermore, the treatments significantly attenuated MCT-induced hypertrophic damage of myocardium, parenchymal injury and collagen deposition in the lungs. Moreover, the treatments attenuated MCT-induced apoptosis and fibrosis in the lungs. The treatments partially restored MCT-induced reductions of bone morphogenetic protein type II receptor (BMPRII) and phosphorylated Smad1/5 in the lungs.

CONCLUSION

SAA ameliorates the pulmonary arterial remodeling in MCT-induced PAH rats most likely via activating the BMPRII-Smad pathway and inhibiting apoptosis. Thus, SAA may have therapeutic potential for the patients at high risk of PAH.

MiRNA-199a-5p influences pulmonary artery hypertension via downregulating Smad3

MicroRNAs (miRNAs) play important roles in pulmonary artery hypertension (PAH). Recently, it has been reported that miR-199a-5p participates in the progression of chronic obstructive pulmonary disease, ventricular hypertrophy and heart failure. However, the roles of miR-199a-5p in PAH are still unclear. In the present study, miR-199a-5p was investigated in PAH rat models and in human pulmonary artery smooth muscle cells (HPASMCs) and endothelial cells (HPAECs). The expression of miR-199a-5p was significantly increased following PAH induction, and anti-miR-199a-5p could increase the nitric oxide (NO) level and decrease the PAH-induced upregulation of pulmonary artery pressure and right ventricular hypertrophy. Moreover, in HPASMCs and HPAECs, miR-199a-5p overexpression could inhibit the level of NO and promote the concentration of Ca(2+), but anti-miR-199a-5p showed opposite results. Further analysis demonstrated that miR-199a-5p attenuated the expression of Smad3. Importantly, Smad3 was confirmed to be the target gene of miR-199a-5p using dual-luciferase reporter assay. Mechanism analyses revealed that the downregulation of NO and the upregulation of Ca(2+) caused by miR-199a-5p were all reversed by Smad3 overexpression in HPASMCs and HPAECs. Moreover, in PAH model, Smad3, p-Smad3 and Smad4 were all downregulated in lung tissues, and SIS3 (Smad3 inhibitor) could reverse the effects of anti-miR-199a-5p in PAH rats. Our date suggest that miR-199a-5p may function as a regulator of PAH by targeting Smad3, indicating a novel therapeutic strategy for patients with PAH.

Targeting BMP signalling in cardiovascular disease and anaemia

Bone morphogenetic proteins (BMPs) and their receptors, known to be essential regulators of embryonic patterning and organogenesis, are also critical for the regulation of cardiovascular structure and function. In addition to their contributions to syndromic disorders including heart and vascular development, BMP signalling is increasingly recognized for its influence on endocrine-like functions in postnatal cardiovascular and metabolic homeostasis. In this Review, we discuss several critical and novel aspects of BMP signalling in cardiovascular health and disease, which highlight the cell-specific and context-specific nature of BMP signalling. Based on advancing knowledge of the physiological roles and regulation of BMP signalling, we indicate opportunities for therapeutic intervention in a range of cardiovascular conditions including atherosclerosis and pulmonary arterial hypertension, as well as for anaemia of inflammation. Depending on the context and the repertoire of ligands and receptors involved in specific disease processes, the selective inhibition or enhancement of signalling via particular BMP ligands (such as in atherosclerosis and pulmonary arterial hypertension, respectively) might be beneficial. The development of selective small molecule antagonists of BMP receptors, and the identification of ligands selective for BMP receptor complexes expressed in the vasculature provide the most immediate opportunities for new therapies.

iTRAQ-Based Quantitative Proteomic Comparison of Early- and Late-Passage Human Dermal Papilla Cell Secretome in Relation to Inducing Hair Follicle Regeneration

Alopecia is an exceedingly prevalent problem that lacks effective therapy. Recently, research has focused on early-passage dermal papilla cells (DPCs), which have hair inducing activity both in vivo and in vitro. Our previous study indicated that factors secreted from early-passage DPCs contribute to hair follicle (HF) regeneration. To identify which factors are responsible for HF regeneration and why late-passage DPCs lose this potential, we collected 48-h-culture medium (CM) from both of passage 3 and 9 DPCs, and subcutaneously injected the DPC-CM into NU/NU mice. Passage 3 DPC-CM induced HF regeneration, based on the emergence of a white hair coat, but passage 9 DPC-CM did not. In order to identify the key factors responsible for hair induction, CM from passage 3 and 9 DPCs was analyzed by iTRAQ-based quantitative proteomic technology. We identified 1360 proteins, of which 213 proteins were differentially expressed between CM from early-passage vs. late-passage DPCs, including SDF1, MMP3, biglycan and LTBP1. Further analysis indicated that the differentially-expressed proteins regulated the Wnt, TGF-β and BMP signaling pathways, which directly and indirectly participate in HF morphogenesis and regeneration. Subsequently, we selected 19 proteins for further verification by multiple reaction monitoring (MRM) between the two types of CM. These results indicate DPC-secreted proteins play important roles in HF regeneration, with SDF1, MMP3, biglycan, and LTBP1 being potential key inductive factors secreted by dermal papilla cells in the regeneration of hair follicles.

MicroRNA-143 Activation Regulates Smooth Muscle and Endothelial Cell Crosstalk in Pulmonary Arterial Hypertension

RATIONALE

The pathogenesis of pulmonary arterial hypertension (PAH) remains unclear. The 4 microRNAs representing the miR-143 and miR-145 stem loops are genomically clustered.

OBJECTIVE

To elucidate the transcriptional regulation of the miR-143/145 cluster and the role of miR-143 in PAH.

METHODS AND RESULTS

We identified the promoter region that regulates miR-143/145 microRNA expression in pulmonary artery smooth muscle cells (PASMCs). We mapped PAH-related signaling pathways, including estrogen receptor, liver X factor/retinoic X receptor, transforming growth factor-β (Smads), and hypoxia (hypoxia response element), that regulated levels of all pri-miR stem loop transcription and resulting microRNA expression. We observed that miR-143-3p is selectively upregulated compared with miR-143-5p during PASMC migration. Modulation of miR-143 in PASMCs significantly altered cell migration and apoptosis. In addition, we found high abundance of miR-143-3p in PASMC-derived exosomes. Using assays with pulmonary arterial endothelial cells, we demonstrated a paracrine promigratory and proangiogenic effect of miR-143-3p-enriched exosomes from PASMC. Quantitative polymerase chain reaction and in situ hybridization showed elevated expression of miR-143 in calf models of PAH and in samples from PAH patients. Moreover, in contrast to our previous findings that had not supported a therapeutic role in vivo, we now demonstrate a protective role of miR-143 in experimental pulmonary hypertension in vivo in miR-143-/- and anti-miR-143-3p-treated mice exposed to chronic hypoxia in both preventative and reversal settings.

CONCLUSIONS

MiR-143-3p modulated both cellular and exosome-mediated responses in pulmonary vascular cells, whereas inhibition of miR-143-3p blocked experimental pulmonary hypertension. Taken together, these findings confirm an important role for the miR-143/145 cluster in PAH pathobiology.

Regulation of chondroitin-4-sulfotransferase (CHST11) expression by opposing effects of arylsulfatase B on BMP4 and Wnt9A

In this report, the gene regulatory mechanism by which decline in arylsulfatase B (ARSB; N-acetylgalactosamine-4-sulfatase) reduces CHST11 (chondroitin-4-sulfotransferase; C4ST) mRNA expression in human colonic epithelial cells and in colonic epithelium of ARSB-deficient mice is presented. ARSB controls the degradation of chondroitin 4-sulfate (C4S) by removing the 4-sulfate group at the non-reducing end of the C4S chain, but has not previously been shown to affect C4S biosynthesis. The decline in CHST11 expression following ARSB reduction is attributable to effects of ARSB on bone morphogenetic protein (BMP)4, since BMP4 expression and secretion declined when ARSB was silenced. Inhibition of BMP4 by neutralizing antibody also reduced CHST11 expression. When C4S was more sulfated due to decline in ARSB, more BMP4 was sequestered by C4S in the cell membrane, and CHST11 expression declined. Exogenous recombinant BMP4, acting through a phospho-Smad3 binding site in the CHST11 promoter, increased the mRNA expression of CHST11. In contrast to the decline in BMP4 that followed decline in ARSB, Wnt9A mRNA expression was previously shown to increase when ARSB was silenced and C4S was more highly sulfated. Galectin-3 bound less to the more highly sulfated C4S, leading to increased nuclear translocation and enhanced galectin-3 interaction with Sp1 in the Wnt9A promoter. Silencing Wnt9A increased the expression of CHST11 in the colonic epithelial cells, and chromatin immunoprecipitation assay demonstrated enhancing effects of Wnt9A siRNA and exogenous BMP4 on the CHST11 promoter through the pSmad3 binding site. These findings suggest that cellular processes mediated by differential effects of Wnt9A and BMP4 can result from opposing effects on CHST11 expression.

Bone Morphogenetic Protein (BMP) signaling in development and human diseases

Bone Morphogenetic Proteins (BMPs) are a group of signaling molecules that belongs to the Transforming Growth Factor-β (TGF-β) superfamily of proteins. Initially discovered for their ability to induce bone formation, BMPs are now known to play crucial roles in all organ systems. BMPs are important in embryogenesis and development, and also in maintenance of adult tissue homeostasis. Mouse knockout models of various components of the BMP signaling pathway result in embryonic lethality or marked defects, highlighting the essential functions of BMPs. In this review, we first outline the basic aspects of BMP signaling and then focus on genetically manipulated mouse knockout models that have helped elucidate the role of BMPs in development. A significant portion of this review is devoted to the prominent human pathologies associated with dysregulated BMP signaling.

Sildenefil increases connexin 40 in smooth muscle cells through activation of BMP pathways in pulmonary arterial hypertension

BACKGROUND

Pulmonary arterial hypertension (PAH) is a cardiovascular disorder associated with enhanced proliferation and suppressed apoptosis of pulmonary arterial smooth muscle cells (PASMCs). The sildenafil can regulate the Connexin (Cx) 43 in the PASMCs and thus inhibit the PASMCs proliferation and the remodeling of pulmonary arterial. However, how sildenafil exert regulation in the Cx40 in the PASMCs in PAH remains unclear.

METHODS AND RESULTS

Using the rat PAH model induced by the monocrotoline, we demonstrated that the Cx40 in the PASMCs is down-regulated in the PAH. The sildenafil promotes the up-regulation of Cx40 in the PASMCs via bone morphogenetic protein (BMP) signaling, accompanied by an anti-proliferative response in PASMCs. Inhibition of the BMP axis reverses the up-regulation of Cx40 and anti-proliferation of the sildenafil in these cells. In monocrotaline-induced PAH rat models, which display reduced levels of BMP signaling, this study further indicates that the BMP-Cx40 axis is activated in lungs following the sildenafil treatment. Furthermore, we also find in vitro that sildenafil increases the Cx40 expression of PASMCs isolated from MCT-PAH rats and inhibit the proliferation of these cells. These phenomenon are reversed by LDN-193189, the antagonist of type II receptor for bone morphogenetic protein (BMPR2) treatment, providing strong evidence for the protect effect of sildenafil and the BMP-Cx40 axis involvement.

CONCLUSIONS

Taken together, these data suggest the sildenafil activate BMP-Cx40 signaling in the PAH. This axis may be a potential therapeutic target in PAH.