Hypoxia inducible factor-1-dependent up-regulation of BMP4 mediates hypoxia-induced increase of TRPC expression in PASMCs

Protective Role of TRPC3 Gene Polymorphism (rs10518289) in Obstructive Sleep Apnea Hypopnea Syndrome Among Hypertensive Patients

BACKGROUND Obstructive sleep apnea-hypopnea syndrome (OSAHS) presents a significant health concern, particularly among individuals with essential hypertension (EH). Understanding the genetic underpinnings of this association is crucial for effective management and intervention. We investigated the relationship between TRPC3 gene polymorphisms and susceptibility to OSAHS in patients with EH. MATERIAL AND METHODS We enrolled 373 patients with EH hospitalized at the First Affiliated Hospital of Xinjiang Medical University between April 2015 and November 2017. Patients were categorized into EH (n=74) and EH+OSAHS (n=299) groups according to the apnea-hypopnea index. Sequenom detection technology was used for TRPC3 gene single-nucleotide polymorphism genotyping, including genotypes at rs953691, rs10518289, rs2292232, rs4995894, rs951974, and rs4292355. RESULTS Sex, smoking history, alcohol history, hypertension duration, fasting blood glucose, urea, creatinine, total cholesterol, HDL-C, LDL-C, glycosylated hemoglobin, 24-h mean systolic BP, and 24-h mean diastolic BP were not significantly different between the 2 groups (P>0.05); however, age, BMI, triglyceride levels differed significantly (P<0.05). No significant difference was detected in distribution frequency of polymorphisms of TRPC3 gene between the 2 groups (P>0.05), while genotype, dominant genotype, and recessive genotype at rs10518289 and alleles at rs4292355 differed significantly (P<0.05). Logistic regression analysis showed age, BMI, and CG+GG genotypes at rs10518289 were risk factors for OSAHS in patients with EH. Interaction between TRPC3 (rs10518289) and obesity was not a risk of OSAHS with EH (P>0.05). CONCLUSIONS CC genotype of rs10518289 in the TRPC3 gene could be a protective genetic marker of OSAHS, and CG+GG genotype may be a risk genetic marker of OSAHS with EH.

Hypoxia-Induced FUS-circTBC1D14 Stress Granules Promote Autophagy in TNBC

Triple-negative breast cancer (TNBC) is a highly aggressive subtype of breast cancer that is suggested to be associated with hypoxia. This study is the first to identify a novel circular RNA (circRNA), circTBC1D14, whose expression is significantly upregulated in TNBC. The authors confirm that high circTBC1D14 expression is associated with a poor prognosis in patients with breast cancer. circTBC1D14-associated mass spectrometry and RNA-binding protein-related bioinformatics strategies indicate that FUS can interact with circTBC1D14, which can bind to the downstream flanking sequence of circTBC1D14 to induce cyclization. FUS is an essential biomarker associated with stress granules (SGs), and the authors find that hypoxic conditions can induce FUS-circTBC1D14-associated SG formation in the cytoplasm after modification by protein PRMT1. Subsequently, circTBC1D14 increases the stability of PRMT1 by inhibiting its K48-regulated polyubiquitination, leading to the upregulation of PRMT1 expression. In addition, FUS-circTBC1D14 SGs can initiate a cascade of SG-linked proteins to recognize and control the elimination of SGs by recruiting LAMP1 and enhancing lysosome-associated autophagy flux, thus contributing to the maintenance of cellular homeostasis and promoting tumor progression in TNBC. Overall, these findings reveal that circTBC1D14 is a potential prognostic indicator that can serve as a therapeutic target for TNBC treatment.

Hypermethylation of the Bmp4 promoter dampens binding of HIF-1α and impairs its cardiac protective effects from oxidative stress in prenatally GC-exposed offspring

The exposure to an unhealthy environment in utero can lead to the occurrence of cardiovascular diseases in the offspring. Glucocorticoids (GC) are essential for normal development and maturation of fetal organs and is a first-line treatment for pregnant women affected by autoimmune diseases. However, excess prenatal GC exposure might program the development of fetal organs and cause a number of chronic diseases in later life. Our previous studies indicated that cardiac functions were significantly compromised in rat offspring prenatally exposed to the synthetic glucocorticoid dexamethasone (DEX), only after ischemia-reperfusion. In the present study, we further observed that DNA hypermethylation of bone morphogenetic protein 4 (Bmp4) promoter in cardiomyocytes caused by prenatal DEX exposure substantially dampened the binding activity of transcription factor HIF-1α induced by cardiac ischemia. Therefore, prenatal DEX exposure inhibits the induction of BMP4 upon I/R and attenuates the protective effects of BMP4 in cardiomyocytes, which eventually manifests as malfunction of the adult heart. Moreover, we employed two cardiac-specific Bmp4 knock-in mouse models and found that in vivo BMP4 overexpression could rescue the cardiac dysfunction caused by prenatal GC exposure. In depth mechanistic research revealed that BMP4 protects the cardiomyocytes from mitophagy and apoptosis by attenuating mitochondrial PGC-1α expression in a p-Smad and Parkin-dependent manner. These findings suggest that prenatal GC exposure increases the susceptibility of the offspring's heart to a "second strike" after birth, due to the failure of hypoxia-induced HIF-1α transactivation of the hypermethylated Bmp4 promoter in cardiomyocytes. Pretreatment with the DNA methylation inhibitor, 5-Aza-2'-deoxycytidine, could be a potential therapeutic method for this programming effect of GC exposure during pregnancy on neonatal cardiac dysfunction.

Crucial Role of Stromal Interaction Molecule-Activated TRPC-ORAI Channels in Vascular Remodeling and Pulmonary Hypertension Induced by Intermittent Hypoxia

Obstructive sleep apnea (OSA), a sleep breathing disorder featured by chronic intermittent hypoxia (CIH), is associate with pulmonary hypertension. Rats exposed to CIH develop lung vascular remodeling and pulmonary hypertension, which paralleled the upregulation of stromal interaction molecule (STIM)-activated TRPC-ORAI Ca2+ channels (STOC) in the lung, suggesting that STOC participate in the pulmonary vascular alterations. Accordingly, to evaluate the role played by STOC in pulmonary hypertension we studied whether the STOC blocker 2-aminoethoxydiphenyl borate (2-APB) may prevent the vascular remodeling and the pulmonary hypertension induced by CIH in a rat model of OSA. We assessed the effects of 2-APB on right ventricular systolic pressure (RVSP), pulmonary vascular remodeling, α-actin and proliferation marker Ki-67 levels in pulmonary arterial smooth muscle cells (PASMC), mRNA levels of STOC subunits, and systemic and pulmonary oxidative stress (TBARS) in male Sprague-Dawley (200 g) rats exposed to CIH (5% O2, 12 times/h for 8h) for 28 days. At 14 days of CIH, osmotic pumps containing 2-APB (10 mg/kg/day) or its vehicle were implanted and rats were kept for 2 more weeks in CIH. Exposure to CIH for 28 days raised RVSP &gt; 35 mm Hg, increased the medial layer thickness and the levels of α-actin and Ki-67 in PASMC, and increased the gene expression of TRPC1, TRPC4, TRPC6 and ORAI1 subunits. Treatment with 2-APB prevented the raise in RVSP and the increment of the medial layer thickness, as well as the increased levels of α-actin and Ki-67 in PASMC, and the increased gene expression of STOC subunits. In addition, 2-APB did not reduced the lung and systemic oxidative stress, suggesting that the effects of 2-APB on vascular remodeling and pulmonary hypertension are independent on the reduction of the oxidative stress. Thus, our results supported that STIM-activated TRPC-ORAI Ca2+ channels contributes to the lung vascular remodeling and pulmonary hypertension induced by CIH.

Bioactivities and mechanisms of natural medicines in the management of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a progressive and rare disease without obvious clinical symptoms that shares characteristics with pulmonary vascular remodeling. Right heart failure in the terminal phase of PAH seriously threatens the lives of patients. This review attempts to comprehensively outline the current state of knowledge on PAH its pathology, pathogenesis, natural medicines therapy, mechanisms and clinical studies to provide potential treatment strategies. Although PAH and pulmonary hypertension have similar pathological features, PAH exhibits significantly elevated pulmonary vascular resistance caused by vascular stenosis and occlusion. Currently, the pathogenesis of PAH is thought to involve multiple factors, primarily including genetic/epigenetic factors, vascular cellular dysregulation, metabolic dysfunction, even inflammation and immunization. Yet many issues regarding PAH need to be clarified, such as the "oestrogen paradox". About 25 kinds monomers derived from natural medicine have been verified to protect against to PAH via modulating BMPR2/Smad, HIF-1α, PI3K/Akt/mTOR and eNOS/NO/cGMP signalling pathways. Yet limited and single PAH animal models may not corroborate the efficacy of natural medicines, and those natural compounds how to regulate crucial genes, proteins and even microRNA and lncRNA still need to put great attention. Additionally, pharmacokinetic studies and safety evaluation of natural medicines for the treatment of PAH should be undertaken in future studies. Meanwhile, methods for validating the efficacy of natural drugs in multiple PAH animal models and precise clinical design are also urgently needed to promote advances in PAH.

The biology of bone morphogenetic protein signaling pathway in cerebrovascular system

Bone morphogenetic protein belongs to transcription growth factor superfamily β; bone morphogenetic protein signal pathway regulates cell proliferation, differentiation, and apoptosis among different tissues. Cerebrovascular system supplies sufficient oxygen and blood into brain to maintain its normal function. The disorder of cerebrovascular system will result into serious cerebrovascular diseases, which is gradually becoming a major threat to human health in modern society. In recent decades, many studies have revealed the underlying biology and mechanism of bone morphogenetic protein signal pathway played in cerebrovascular system. This review will discuss the relationship between the two aspects, aiming to provide new perspective for non-invasive treatment and basic research of cerebrovascular diseases.

Cellular Pathways Promoting Pulmonary Vascular Remodeling by Hypoxia

Exposure to hypoxia increases pulmonary vascular resistance, leading to elevated pulmonary arterial pressure and, potentially, right heart failure. Vascular remodeling is an important contributor to the increased pulmonary vascular resistance. Hyperproliferation of smooth muscle, endothelial cells, and fibroblasts, and deposition of extracellular matrix lead to increased wall thickness, extension of muscle into normally non-muscular arterioles, and vascular stiffening. This review highlights intrinsic and extrinsic modulators contributing to the remodeling process.

Epigenetic modification cooperates with Zeb1 transcription factor to regulate Bmp4 to promote chicken PGCs formation

BMP4 is the critical gene of primordial germ cell formation in mammal, however, the mechanism of PGCs formation in chicken still unknown. In this research, we compared the evolution relationship of different species. Although the protein sequence is highly conservative between mouse, human and chicken, promotors vary among avian and mammal species. Therefore, it is easily to predict that there would be different regulation mechanism of Bmp4 expression in chicken. Here, we elucidate the function of chicken Bmp4 during PGCs formation. In vivo, Bmp4 can promote PGCs development and migration, and increase the expression of key genes (Cvh, c-kit, cxcr4, etc.). Whereas, the expression of these genes will decrease after knocking out Bmp4. After over-expression and knockout Bmp4 in vitro, we found that overexpression of Bmp4 could promote the formation of embryoid bodies (EB) and up-regulate the key genes of PGCs formation and migration, while knockout Bmp4 could inhibit the formation of embryoid bodies and decrease the expression of related genes. Flow and indirect immunofluorescence also indicated the same result. These all results proved that chicken Bmp4 could also promote the formation of PGCs. Furthermore, dual-luciferase activity detection showed that the promotor activity of Bmp4 was positively regulated by transcription factor Zeb1. Overexpression of Zeb1 can also increase the mRNA and protein expression of Bmp4. At the same time, DNA methylation inhibited Bmp4 transcription and histone methylation was able to promote its transcription. In conclusion, this study established that chicken Bmp4 can promote the formation of chicken PGCs. This gene is regulated by DNA, histone methylation and transcription factor Zeb1. These results lay a theoretical foundation for exploring the function and molecular mechanism of Bmp4 in the process of PGCs formation.

Proteomic analysis of hypoxia and non-hypoxia secretome mesenchymal stem-like cells from human breastmilk

Introduction

Breastmilk contains proteins and cells which have stem cell properties. The human breastmilk stem cell mimick mesenchymal stem cells and expresses pluripotency genes. The protein level of breastmilk is high in colostrum and gradually subsides in the first year of lactation. The mesenchymal stem cells from breastmilk can be an alternative source of stem cells that can potentially affect cardiovascular therapy. This study aimed to identify the proteomic analysis of secretome mesenchymal stem-like cells under hypoxia compared to non-hypoxia from human breastmilk stem cells.

Material and methods

The human breastmilk was collected from six healthy breastfeeding women and transported to the laboratory under aseptic conditions. The breastmilk cells were isolated then cultured. After 72 h, the human breastmilk stem cells reached confluence then cleaned up and isolated in serum-free media (spheroid) to allow serial passaging every 48 h. The acquisition stem cell was made with flow cytometry. The cells were divided into hBSC secretomes under hypoxia (A) and non-hypoxia (B) and analyzed for LC-MS to identify the peptide structure.

Results

The human breastmilk cells contained several mesenchymal stem-like cells in density 2.4 × 10⁶ cell/mL for hypoxia and 2 × 10⁶ cell/mL for non-hypoxia conditions. The human breastmilk stem cell surface markers derived from the third cell passage process were 93.77% for CD44, 98.69% for CD73, 88.45% for CD90, and 96.30% for CD105. The protein level of secretome mesenchymal stem -like cells under hypoxia was measured at 5.56 μg/mL and 4.28 μg/mL for non-hypoxia. The liquid chromatography-mass spectrometry analysis identified 130 and 59 peptides from hypoxia and non-hypoxia of the human breastmilk stem cell secretome sequentially. Some important proteomics structures were found in the hypoxic human breastmilk stem cell secretome, such as transforming growth factor-β, VE-cadherin, and caspase.

Conclusion

The human breastmilk cells contain mesenchymal stem-like cells and a high concentration of CD44, CD73, CD90, and CD105 as surface markers at third passage culture. The hypoxic hBSC secretome produces a higher protein level compare to non-hypoxia. The transforming growth factor -β was found in the hypoxic hBSC secretome as a modulator of VEGF-mediated angiogenesis.

Androgens regulate ovarian gene expression by balancing Ezh2-Jmjd3 mediated H3K27me3 dynamics

Conventionally viewed as male hormone, androgens play a critical role in female fertility. Although androgen receptors (AR) are transcription factors, to date very few direct transcriptional targets of ARs have been identified in the ovary. Using mouse models, this study provides three critical insights about androgen-induced gene regulation in the ovary and its impact on female fertility. First, RNA-sequencing reveals a number of genes and biological processes that were previously not known to be directly regulated by androgens in the ovary. Second, androgens can also influence gene expression by decreasing the tri-methyl mark on lysine 27 of histone3 (H3K27me3), a gene silencing epigenetic mark. ChIP-seq analyses highlight that androgen-induced modulation of H3K27me3 mark within gene bodies, promoters or distal enhancers have a much broader impact on ovarian function than the direct genomic effects of androgens. Third, androgen-induced decrease of H3K27me3 is mediated through (a) inhibiting the expression and activity of Enhancer of Zeste Homologue 2 (EZH2), a histone methyltransferase that promotes tri-methylation of K27 and (b) by inducing the expression of a histone demethylase called Jumonji domain containing protein-3 (JMJD3/KDM6B), responsible for removing the H3K27me3 mark. Androgens through the PI3K/Akt pathway, in a transcription-independent fashion, increase hypoxia-inducible factor 1 alpha (HIF1α) protein levels, which in turn induce JMJD3 expression. Furthermore, proof of concept studies involving in vivo knockdown of Ar in the ovary and ovarian (granulosa) cell-specific Ar knockout mouse model show that ARs regulate the expression of key ovarian genes through modulation of H3K27me3.

Histidine decarboxylase deficiency inhibits NBP-induced extramedullary hematopoiesis by modifying bone marrow and spleen microenvironments

Histidine decarboxylase (HDC), a histamine synthase, is expressed in various hematopoietic cells and is induced by hematopoietic cytokines such as granulocyte colony-stimulating factor (G-CSF). We previously showed that nitrogen-containing bisphosphonate (NBP)-treatment induces extramedullary hematopoiesis via G-CSF stimulation. However, the function of HDC in NBP-induced medullary and extramedullary hematopoiesis remains unclear. Here, we investigated changes in hematopoiesis in wild-type and HDC-deficient (HDC-KO) mice. NBP treatment did not induce anemia in wild-type or HDC-KO mice, but did produce a gradual increase in serum G-CSF levels in wild-type mice. NBP treatment also enhanced Hdc mRNA expression and erythropoiesis in the spleen and reduced erythropoiesis in bone marrow and the number of vascular adhesion molecule 1 (VCAM-1)-positive macrophages in wild-type mice, as well as increased the levels of hematopoietic progenitor cells and proliferating cells in the spleen and enhanced expression of bone morphogenetic protein 4 (Bmp4), CXC chemokine ligand 12 (Cxcl12), and hypoxia inducible factor 1 (Hif1) in the spleen. However, such changes were not observed in HDC-KO mice. These results suggest that histamine may affect hematopoietic microenvironments of the bone marrow and spleen by changing hematopoiesis-related factors in NBP-induced extramedullary hematopoiesis.

Mechanisms of vasculogenic mimicry in hypoxic tumor microenvironments

Background

Vasculogenic mimicry (VM) is a recently discovered angiogenetic process found in many malignant tumors, and is different from the traditional angiogenetic process involving vascular endothelium. It involves the formation of microvascular channels composed of tumor cells; therefore, VM is considered a new model for the formation of new blood vessels in aggressive tumors, and can provide blood supply for tumor growth. Many studies have pointed out that in recent years, some clinical treatments against angiogenesis have not been satisfactory possibly due to the activation of VM. Although the mechanisms underlying VM have not been fully elucidated, increasing research on the soil “microenvironment” for tumor growth suggests that the initial hypoxic environment in solid tumors is inseparable from VM.

Main body

In this review, we describe that the stemness and differentiation potential of cancer stem cells are enhanced under hypoxic microenvironments, through hypoxia-induced epithelial-endothelial transition (EET) and extracellular matrix (ECM) remodeling to form the specific mechanism of vasculogenic mimicry; we also summarized some of the current drugs targeting VM through these processes, suggesting a new reference for the clinical treatment of tumor angiogenesis.

Conclusion

Overall, the use of VM inhibitors in combination with conventional anti-angiogenesis treatments is a promising strategy for improving the effectiveness of targeted angiogenesis treatments; further, considering the importance of hypoxia in tumor invasion and metastasis, drugs targeting the hypoxia signaling pathway seem to achieve good results.

Consecutive Hypoxia Decreases Expression of NOTCH3, HEY1, CC10, and FOXJ1 via NKX2-1 Downregulation and Intermittent Hypoxia-Reoxygenation Increases Expression of BMP4, NOTCH1, MKI67, OCT4, and MUC5AC via HIF1A Upregulation in Human Bronchial Epithelial Cells

Previous studies have shown that the experimental models of hypoxia-reoxygenation (H/R) mimics the physiological conditions of ischemia-reperfusion and induce oxidative stress and injury in various types of organs, tissues, and cells, both in vivo and in vitro, including human lung adenocarcinoma epithelial cells. Nonetheless, it had not been reported whether H/R affected proliferation, apoptosis, and expression of stem/progenitor cell markers in the bronchial epithelial cells. In this study, we investigated differential effects of consecutive hypoxia and intermittent 24/24-h cycles of H/R on human bronchial epithelial (HBE) cells derived from the same-race and age-matched healthy subjects (i.e., NHBE) and subjects with chronic obstructive pulmonary disease (COPD) (i.e., DHBE). To analyze gene/protein expression during differentiation, both the NHBE and DHBE cells at the 2nd passage were cultured at the air-liquid interface (ALI) in the differentiation medium under normoxia for 3 days, followed by either culturing under hypoxia (1% O₂) for consecutively 9 days and then returning to normoxia for another 9 days, or culturing under 24/24-h cycles of H/R (i.e., 24 h of 1% O₂ followed by 24 h of 21% O₂, repetitively) for 18 days in total, so that all differentiating HBE cells were exposed to hypoxia for a total of 9 days. In both the normal and diseased HBE cells, intermittent H/R significantly increased HIF1A, BMP4, NOTCH1, MKI67, OCT4, and MUC5AC expression, while consecutive hypoxia significantly decreased NKX2-1, NOTCH3, HEY1, CC10, and FOXJ1 expression. Inhibition of HIF1A or NKX2-1 expression by siRNA transfection respectively decreased BMP4/NOTCH1/MKI67/OCT4/MUC5AC and NOTCH3/HEY1/CC10/FOXJ1 expression in the HBE cells cultured under intermittent H/R to the same levels under normoxia. Overexpression of NKX2-1 via cDNA transfection caused more than 2.8-fold increases in NOTCH3, HEY1, and FOXJ1 mRNA levels in the HBE cells cultured under consecutive hypoxia compared to the levels under normoxia. Taken together, our results show for the first time that consecutive hypoxia decreased expression of the co-regulated gene module NOTCH3/HEY1/CC10 and the ciliogenesis-inducing transcription factor gene FOXJ1 via NKX2-1 mRNA downregulation, while intermittent H/R increased expression of the co-regulated gene module BMP4/NOTCH1/MKI67/OCT4 and the predominant airway mucin gene MUC5AC via HIF1A mRNA upregulation.

Energy metabolism: A newly emerging target of BMP signaling in bone homeostasis

Energy metabolism is the process of generating energy (i.e. ATP) from nutrients. This process is indispensable for cell homeostasis maintenance and responses to varying conditions. Cells require energy for growth and maintenance and have evolved to have multiple pathways to produce energy. Both genetic and functional studies have demonstrated that energy metabolism, such as glucose, fatty acid, and amino acid metabolism, plays important roles in the formation and function of bone cells including osteoblasts, osteocytes, and osteoclasts. Dysregulation of energy metabolism in bone cells consequently disturbs the balance between bone formation and bone resorption. Metabolic diseases have also been reported to affect bone homeostasis. Bone morphogenic protein (BMP) signaling plays critical roles in regulating the formation and function of bone cells, thus affecting bone development and homeostasis. Mutations of BMP signaling-related genes in mice have been reported to show abnormalities in energy metabolism in many tissues, including bone. In addition, BMP signaling correlates with critical signaling pathways such as mTOR, HIF, Wnt, and self-degradative process autophagy to coordinate energy metabolism and bone homeostasis. These findings will provide a newly emerging target of BMP signaling and potential therapeutic strategies and the improved management of bone diseases. This review summarizes the recent advances in our understanding of (1) energy metabolism in regulating the formation and function of bone cells, (2) function of BMP signaling in whole body energy metabolism, and (3) mechanistic interaction of BMP signaling with other signaling pathways and biological processes critical for energy metabolism and bone homeostasis.

Heart‑lung crosstalk in pulmonary arterial hypertension following myocardial infarction (Review)

Left heart disease is the main cause of clinical pulmonary arterial hypertension (PAH). Common types of left heart disease that result in PAH include heart failure, left ventricular systolic dysfunction, left ventricular diastolic dysfunction and valvular disease. It is currently believed that mechanical pressure caused by high pulmonary venous pressure is the main cause of myocardial infarction (MI) in individuals with ischemic cardiomyopathy and left ventricular systolic dysfunction. In the presence of decreased cardiac function, vascular remodeling of pulmonary vessels in response to long-term stimulation by high pressure in turn leads to exacerbation of PAH. However, the underlying pathological mechanisms remain unclear. Elucidating the association between the development of MI and PAH may lead to a better understanding of potential risk factors and better disease treatment. In this article, the pathophysiological effects of multiple systems in individuals with MI and PAH were reviewed in order to provide a general perspective on various potential interactions between cardiomyocytes and pulmonary vascular cells.

Oxygen homeostasis and cardiovascular disease: A role for HIF?

Hypoxia, the decline of tissue oxygen stress, plays a role in mediating cellular processes. Cardiovascular disease, relatively widespread with increased mortality, is closely correlated with oxygen homeostasis regulation. Besides, hypoxia-inducible factor-1(HIF-1) is reported to be a crucial component in regulating systemic hypoxia-induced physiological and pathological modifications like oxidative stress, damage, angiogenesis, vascular remodeling, inflammatory reaction, and metabolic remodeling. In addition, HIF1 controls the movement, proliferation, apoptosis, differentiation and activity of numerous core cells, such as cardiomyocytes, endothelial cells (ECs), smooth muscle cells (SMCs), and macrophages. Here we review the molecular regulation of HIF-1 in cardiovascular diseases, intended to improve therapeutic approaches for clinical diagnoses. Better knowledge of the oxygen balance control and the signal mechanisms involved is important to advance the development of hypoxia-related diseases.

TRPC channels: Structure, function, regulation and recent advances in small molecular probes

Transient receptor potential canonical (TRPC) channels constitute a group of receptor-operated calcium-permeable nonselective cation channels of the TRP superfamily. The seven mammalian TRPC members, which can be further divided into four subgroups (TRPC1, TRPC2, TRPC4/5, and TRPC3/6/7) based on their amino acid sequences and functional similarities, contribute to a broad spectrum of cellular functions and physiological roles. Studies have revealed complexity of their regulation involving several components of the phospholipase C pathway, G_i and G_o proteins, and internal Ca²⁺ stores. Recent advances in cryogenic electron microscopy have provided several high-resolution structures of TRPC channels. Growing evidence demonstrates the involvement of TRPC channels in diseases, particularly the link between genetic mutations of TRPC6 and familial focal segmental glomerulosclerosis. Because TRPCs were discovered by the molecular identity first, their pharmacology had lagged behind. This is rapidly changing in recent years owning to great efforts from both academia and industry. A number of potent tool compounds from both synthetic and natural products that selective target different subtypes of TRPC channels have been discovered, including some preclinical drug candidates. This review will cover recent advancements in the understanding of TRPC channel regulation, structure, and discovery of novel TRPC small molecular probes over the past few years, with the goal of facilitating drug discovery for the study of TRPCs and therapeutic development.

SGK1 Mediates Hypoxic Pulmonary Hypertension through Promoting Macrophage Infiltration and Activation

Inflammation plays a pivotal role in the development of pulmonary arterial hypertension (PAH). Meanwhile, serum glucocorticoid-regulated kinase-1 (SGK1) has been considered to be an important factor in the regulation of inflammation in some vascular disease. However, the role of SGK1 in hypoxia-induced inflammation and PAH is still unknown. WT and SGK1^−/− mice were exposed to chronic hypoxia to induce PAH. The quantitative PCR and immunohistochemistry were used to determine the expression of SGK1. The right ventricular hypertrophy index (RVHI), RV/BW ratio, right ventricle systolic pressure (RVSP), and percentage of muscularised vessels and medical wall thickness were measured to evaluate PAH development. The infiltration of macrophages and localization of SGK1 on cells were examined by histological analysis. The effects of SGK1 on macrophage function and cytokine expression were assessed by comparing WT and SGK1^−/− macrophages in vitro. SGK1 has high expression in hypoxia-induced PAH. Deficiency of SGK1 prevented the development of hypoxia-induced PAH and inhibited macrophage infiltration in the lung. In addition, SGK1 knockout inhibited the expression of proinflammatory cytokines in macrophages. SGK1-induced macrophage activation and proinflammatory response contributes to the development of PAH in hypoxia-treated mice. Thus, SGK1 might be considered a promising target for PAH treatment.

Trpc1 as the Missing Link Between the Bmp and Ca2+ Signalling Pathways During Neural Specification in Amphibians

In amphibians, the inhibition of bone morphogenetic protein (BMP) in the dorsal ectoderm has been proposed to be responsible for the first step of neural specification, called neural induction. We previously demonstrated that in Xenopus laevis embryos, the BMP signalling antagonist, noggin, triggers an influx of Ca²⁺ through voltage-dependent L-type Ca²⁺ channels (LTCCs), mainly via Ca_V1.2, and we showed that this influx constitutes a necessary and sufficient signal for triggering the expression of neural genes. However, the mechanism linking the inhibition of BMP signalling with the activation of LTCCs remained unknown. Here, we demonstrate that the transient receptor potential canonical subfamily member 1, (Trpc1), is an intermediate between BMP receptor type II (BMPRII) and the Ca_V1.2 channel. We show that noggin induces a physical interaction between BMPRII and Trpc1 channels. This interaction leads to the activation of Trpc1 channels and to an influx of cations, which depolarizes the plasma membrane up to a threshold sufficient to activate Cav1.2. Together, our results demonstrate for the first time that during neural induction, Ca²⁺ entry through the Ca_V1.2 channel results from the noggin-induced interaction between Trpc1 and BMPRII.

Inactivation of carboxyl terminus of Hsc70-interacting protein prevents hypoxia-induced pulmonary arterial smooth muscle cells proliferation by reducing intracellular Ca2+ concentration

Carboxyl terminus of Hsc70-interacting protein (CHIP) is a 35-kDa cytoplasmic protein expressed in human striated muscle, brain, aortic smooth muscle, endothelial cells, and other tissues. Studies have confirmed that CHIP regulates cell growth, apoptosis, cell phenotype, metabolism, neurodegeneration, etc. However, whether CHIP is involved in pulmonary artery smooth muscle cell (PASMC) proliferation, a vital contributor to chronic hypoxia-induced pulmonary hypertension (CHPH), remains unknown. In this study, we first evaluated CHIP expression in the pulmonary arteries (PAs) of CHPH model rats. Subsequently, by silencing CHIP, we investigated the effect of CHIP on hypoxia-induced PASMC proliferation and the underlying mechanism. Our results showed that CHIP expression was upregulated in the PAs of CHPH model rats. Silencing CHIP significantly suppressed the hypoxia-triggered promotion of proliferation, [Ca²⁺]_i, store-operated Ca²⁺ entry (SOCE), and some regulators of SOCE such as TRPC1 and TRPC6 in cultured PASMCs. These results indicate that CHIP likely contributes to hypoxia-induced PASMC proliferation by targeting the SOCE-[Ca²⁺]_i pathway through the regulation of TRPC1 and TRPC6 in the PASMCs. In conclusion, the findings of the current study clarify the role of CHIP in hypoxia-induced PASMC proliferation.

H2S attenuates endoplasmic reticulum stress in hypoxia-induced pulmonary artery hypertension

Background: Previous studies have found that hydrogen sulfide (H₂S) has multiple functions such as anti-inflammatory, antioxidative in addition to biological effects among the various organs. Exaggerated proliferation and resistance to apoptosis of pulmonary artery smooth muscle cells (PASMCs) is a key component of vascular remodeling. We hypothesized that endogenous bioactive molecular known to suppress endoplasmic reticulum (ER) stress signaling, like H₂S, will inhibit the disruption of the ER-mitochondrial unit and prevent/reverse pulmonary arterial hypertension (PAH).

Methods and results: A hypoxic model was established with PASMCs to investigate the possible role of H₂S in PAH. Effects of H₂S on proliferation of PASMCs were evaluated by CCK-8 and EdU assay treated with or without GYY4137 (donor of H₂S). H₂S significantly inhibited hypoxia-induced increase in PASMCs proliferation in a dose-dependent manner. H₂S by intraperitoneal injection with rats both prevented and reversed chronic hypoxia-induced pulmonary hypertension in rats, decreasing pulmonary vascular resistance, pulmonary artery remodeling and right ventricular hypertrophy, and improving functional capacity without affecting systemic hemodynamic. Exogenous H₂S suppressed ER stress indexes in vivo and in vitro, decreased activating transcription factor 6 activation, and inhibited the hypoxia-induced decrease in mitochondrial calcium and mitochondrial function.

Conclusion: H₂S effectively inhibits hypoxia-induced increase in cell proliferation, migration, and oxidative stress in PASMCs, and NOX-4 might be the underlying mechanism of PAH. Attenuating ER stress with exogenous H₂S may be a novel therapeutic strategy in pulmonary hypertension with high translational potential.

Generation of Vascular Networks from Adipocytes In Vitro

Multipotent cells derived from white mature adipocytes, referred to as dedifferentiated fat (DFAT) cells have the capacity differentiate into endothelial cells. The objective of this study was to modify the isolation method for DFAT cells in order to optimize the endothelial lineage potential. The adipocytes were preincubated for 24 hours, washed, and then incubated for 5 days to allow the generated DFAT cells to remain in proximity to the adipocytes while the cells aggregated into cell clusters. The DFAT cells rapidly differentiated into adipocytes after which endothelial-like cells (ECs) emerged and formed tube-like structure closely associated with the newly differentiated adipocytes. The lipid-filled cells then gradually disappeared whereas the network of tube structure expanded over the course of 3 weeks. ECs accounted for 35-45% of the cells derived from the DFAT cells, as assessed by qPCR, immunofluorescence and fluorescence-activated cell sorting. The DFAT cell-derived ECs could also be further enriched by magnetic sorting, thereby serving as a mouse cell line for further research.

Aqp-1 Gene Knockout Attenuates Hypoxic Pulmonary Hypertension of Mice

Objective—

Hypoxic pulmonary hypertension (HPH) is characterized by proliferative vascular remodeling. Abnormal pulmonary artery smooth muscle cells proliferation and endothelial dysfunction are the primary cellular bases of vascular remodeling. AQP1 (aquaporin-1) is regulated by oxygen level and has been observed to play a role in the proliferation and migration of pulmonary artery smooth muscle cells. The role of AQP1 in HPH pathogenesis has not been directly determined to date. To determine the possible roles of AQP1 in the pathogenesis of HPH and explore its possible mechanisms.

Approach and Results—

Aqp1 knockout mice were used, and HPH model was established in this study. Primary pulmonary artery smooth muscle cells, primary mouse lung endothelial cells, and lung tissue sections from HPH model were used. Immunohistochemistry, immunofluorescence and Western blot, cell cycle, apoptosis, and migration analysis were performed in this study. AQP1 expression was upregulated by chronic hypoxia exposure, both in pulmonary artery endothelia and medial smooth muscle layer of mice. Aqp1 deficiency attenuated the elevation of right ventricular systolic pressures and mitigated pulmonary vascular structure remodeling. AQP1 deletion reduced abnormal cell proliferation in pulmonary artery and accompanied with accumulation of HIF (hypoxia-inducible factor). In vitro, Aqp1 deletion reduced hypoxia-induced proliferation, apoptosis resistance, and migration ability of primary cultured pulmonary artery smooth muscle cells and repressed HIF-1α protein stability. Furthermore, Aqp1 deficiency protected lung endothelial cells from apoptosis in response to hypoxic injury.

Conclusions—

Our data showed that Aqp1 deficiency could attenuate hypoxia-induced vascular remodeling in the development of HPH. AQP1 may be a potential target for pulmonary hypertension treatment.

Assessment of noggin level in pulmonary arterial hypertension patients

Noggin (NOG) is a protein that is involved in the development of many body tissues, including nerve tissue, muscles, and bones. The NOG protein plays a role in germ layer-specific derivation of specialized cells. Via NOG, the formation of neural tissues, the notochord, hair follicles, and eye structures arise from the ectoderm germ layer, while noggin activity in the mesoderm gives way to the formation of cartilage, bone and muscle growth. In the endoderm, NOG is involved in the development of the lungs.

NOG dimerizes by a core body, while two pairs of strands extend from it preceding by an N-terminal segment (called a clip segment) with approximately 20 amino acids. This clip twists around the BMP ligand and obstructs the growth factor surfaces from binding to both BMP receptors type I and type II. NOG binding to some BMPs inhibits these from combining and thus activating receptors of BMP, therefore, blocking non-Smad and Smad-dependent signaling.

The anti-proliferative noggin has particular effects in pulmonary arterial smooth muscle cells (PASMCs) that are exposed to specifically down regulated hypoxia. This occurs together with the BMP4 up-regulation levels of protein, and this imbalance between NOG and BMP4 consequence results in the activation and development of PAH disease. Our study consists of numerous examinations so as to explore new biomarkers in order to determine onset of PAH, and to discover the relationship between NOG serum level and gender, age, body mass index (BMI), waist circumferences (WC), smoking, types of PAH primaries and secondaries, as well as their grade.

Effects of curcumin on hypoxia-inducible factor as a new therapeutic target

Hypoxia-inducible factor-1 (HIF-1) is a transcription factor that consists of two subunits, the HIF-1α and HIF-1β (ARNT). Under hypoxic conditions, HIF-1 is an adaptive system that regulates the transcription of multiple genes associated with growth, angiogenesis, proliferation, glucose transport, metabolism, pH regulation and cell death. However, aberrant HIF-1 activation contributes to the pathophysiology of several human diseases such as cancer, ischemic cardiovascular disorders, and pulmonary and kidney diseases. A growing body of evidence indicates that curcumin, a natural bioactive compound of turmeric root, significantly targets both HIF-1 subunits, but is more potent against HIF-1α. In this review, we have summarized the knowledge about the pharmacological effects of curcumin on HIF-1 and the related molecular mechanisms that may be effective candidates for the development of multi-targeted therapy for several human diseases.

A current view of G protein-coupled receptor - mediated signaling in pulmonary hypertension: finding opportunities for therapeutic intervention

Pathological vascular remodeling is observed in various cardiovascular diseases including pulmonary hypertension (PH), a disease of unknown etiology that has been characterized by pulmonary artery vasoconstriction, right ventricular hypertrophy, vascular inflammation, and abnormal angiogenesis in pulmonary circulation. G protein-coupled receptors (GPCRs) are the largest family in the genome and widely expressed in cardiovascular system. They regulate all aspects of PH pathophysiology and represent therapeutic targets. We overview GPCRs function in vasoconstriction, vasodilation, vascular inflammation-driven remodeling and describe signaling cross talk between GPCR, inflammatory cytokines, and growth factors. Overall, the goal of this review is to emphasize the importance of GPCRs as critical signal transducers and targets for drug development in PH.

BMP9 counteracts the tumorigenic and pro-angiogenic potential of glioblastoma

Glioblastoma multiforme (GBM) is a highly vascularized and aggressive brain tumor, with a strong ability to disseminate and invade the surrounding parenchyma. In addition, a subpopulation of GBM stem cells has been reported to possess the ability to transdifferentiate into tumor-derived endothelial cells (TDECs), supporting the resistance to anti-angiogenic treatments of newly formed blood vessels. Bone Morphogenetic Protein 9 (BMP9) is critically involved in the processes of cancer cell differentiation, invasion and metastasis, representing a potential tool in order to impair the intrinsic GBM aggressiveness. Here we demonstrate that BMP9 is able to trigger the activation of SMADs in patient-derived GBM cells, and to strongly inhibit proliferation and invasion by reducing the activation of PI3K/AKT/MAPK and RhoA/Cofilin pathways, respectively. Intriguingly, BMP9 treatment is sufficient to induce a strong differentiation of GBM stem-like cells and to significantly counteract the already reported process of GBM cell transdifferentiation into TDECs not only in in vitro mimicked TDEC models, but also in vivo in orthotopic xenografts in mice. Additionally, we describe a strong BMP9-mediated inhibition of the whole angiogenic process engaged during GBM tumor formation. Based on these results, we believe that BMP9, by acting at multiple levels against GBM cell aggressiveness, can be considered a promising candidate, to be further developed, for the future therapeutic management of GBM.

Salvia miltiorrhiza: A Potential Red Light to the Development of Cardiovascular Diseases

Salvia miltiorrhiza Bunge, also known as Danshen in Chinese, has been widely used to treat cardiovascular diseases (CVD) in China and other Asia countries. Here, we summarize literatures of the historical traditional Chinese medicine (TCM) interpretation of the action of Salvia miltiorrhiza, its use in current clinical trials, its main phytochemical constituents and its pharmacological findings by consulting Pubmed, China Knowledge Resource Integrated, China Science and Technology Journal, and the Web of Science Databases. Since 2000, 39 clinical trials have been identified that used S. miltiorrhiza in TCM prescriptions alone or with other herbs for the treatment of patients with CVD. More than 200 individual compounds have been isolated and characterized from S. miltiorrhiza, which exhibited various pharmacological activities targeting different pathways for the treatment of CVD in various animal and cell models. The isolated compounds may provide new perspectives in alternative treatment regimes and reveal novel chemical scaffolds for the development of anti-CVD drugs. Meanwhile, there are also some rising concerns of the potential side effects and drug-drug interactions of this plant. The insights gained from this study will help us to better understanding of the actions of this herb for management of cardiovascular disorders. As an herb of red root, S. miltiorrhiza will act as a potential red light to prevent the development of CVD.

Pharmacological activation of PPARγ inhibits hypoxia-induced proliferation through a caveolin-1-targeted and -dependent mechanism in PASMCs

Previously, we and others have demonstrated that activation of peroxisome proliferator-activated receptor γ (PPARγ) by specific pharmacological agonists inhibits the pathogenesis of chronic hypoxia-induced pulmonary hypertension (CHPH) by suppressing the proliferation and migration in distal pulmonary arterial smooth muscle cells (PASMCs). Moreover, these beneficial effects of PPARγ are mediated by targeting the intracellular calcium homeostasis and store-operated calcium channel (SOCC) proteins, including the main caveolae component caveolin-1. However, other than the caveolin-1 targeted mechanism, in this study, we further uncovered a caveolin-1 dependent mechanism within the activation of PPARγ by the specific agonist GW1929. First, effective knockdown of caveolin-1 by small-interfering RNA (siRNA) markedly abolished the upregulation of GW1929 on PPARγ expression at both mRNA and protein levels; Then, in HEK293T, which has previously been reported with low endogenous caveolin-1 expression, exogenous expression of caveolin-1 significantly enhanced the upregulation of GW1929 on PPARγ expression compared with nontransfection control. In addition, inhibition of PPARγ by either siRNA or pharmacological inhibitor T0070907 led to increased phosphorylation of cellular mitogen-activated protein kinases ERK1/2 and p38. In parallel, GW1929 dramatically decreased the expression of the proliferative regulators (cyclin D1 and PCNA), whereas it increased the apoptotic factors (p21, p53, and mdm2) in hypoxic PASMCs. Furthermore, these effects of GW1929 could be partially reversed by recovery of the drug treatment. In combination, PPARγ activation by GW1929 reversibly drove the cell toward an antiproliferative and proapoptotic phenotype in a caveolin-1-dependent and -targeted mechanism.

Canonical Transient Receptor Potential Channels and Their Link with Cardio/Cerebro-Vascular Diseases

The canonical transient receptor potential channels (TRPCs) constitute a series of nonselective cation channels with variable degrees of Ca²⁺ selectivity. TRPCs consist of seven mammalian members, TRPC1, TRPC2, TRPC3, TRPC4, TRPC5, TRPC6, and TRPC7, which are further divided into four subtypes, TRPC1, TRPC2, TRPC4/5, and TRPC3/6/7. These channels take charge of various essential cell functions such as contraction, relaxation, proliferation, and dysfunction. This review, organized into seven main sections, will provide an overview of current knowledge about the underlying pathogenesis of TRPCs in cardio/cerebrovascular diseases, including hypertension, pulmonary arterial hypertension, cardiac hypertrophy, atherosclerosis, arrhythmia, and cerebrovascular ischemia reperfusion injury. Collectively, TRPCs could become a group of drug targets with important physiological functions for the therapy of human cardio/cerebro-vascular diseases.

Bone morphogenetic protein signalling in pulmonary hypertension: advances and therapeutic implications

NEW FINDINGS

What is the topic of this review? This review covers recent evidence highlighting the crucial pathophysiological roles and molecular mechanisms of the bone morphogenetic protein (BMP) signalling pathway during the progression of pulmonary hypertension (PH) and discusses targeting of BMP signalling as a new treatment option against PH. What advances does it highlight? A series of breakthrough findings have greatly enriched our understanding about the mechanism of action of BMP signalling in PH and proved the feasibility of BMP targeting strategies in experimental PH models. This review collects these ideas and discusses the frontiers of BMP signalling-targeted PH therapy at different steps of the signal transduction. The bone morphogenetic protein (BMP)-mediated signalling pathway plays crucial roles in the development and progression of pulmonary hypertension (PH). Typical BMP signalling involves BMP ligands, specific transmembrane serine/threonine kinase receptors, cellular responsive kinases and secreted antagonists. As more and more studies have been conducted, the specific protective or pathogenic roles of these molecules within all these subgroups of BMP signalling have been continuously uncovered. Based on this evidence, specific strategies have been designed by targeting these factors as a new treatment approach to PH. In this review, we have collected recent advances in the exciting findings that link BMP signalling with the pathogenesis of PH and we discuss the potential future frontiers in therapeutic design.

Targeting Hypoxia Inducible Factors-1α As a Novel Therapy in Fibrosis

Fibrosis, characterized by increased extracellular matrix (ECM) deposition, and widespread vasculopathy, has the prominent trait of chronic hypoxia. Hypoxia inducible factors-1α (HIF-1α), a key transcriptional factor in response to this chronic hypoxia, is involved in fibrotic disease, such as Systemic sclerosis (SSc). The implicated function of HIF-1α in fibrosis include stimulation of excessive ECM, vascular remodeling, and futile angiogenesis with further exacerbation of chronic hypoxia and deteriorate pathofibrogenesis. This review will focus on the molecular biological behavior of HIF-1α in regulating progressive fibrosis. Better understanding of the role for HIF-1α-regulated pathways in fibrotic disease will accelerate development of novel therapeutic strategies that target HIF-1α. Such new therapeutic strategies may be particularly effective for treatment of the prototypic, multisystem fibrotic, autoimmune disease SSc.

TRPC1 is a differential regulator of hypoxia-mediated events and Akt signalling in PTEN-deficient breast cancer cells

Hypoxia is a feature of the tumour microenvironment that promotes invasiveness, resistance to chemotherapeutics and cell survival. Our studies identify the transient receptor potential canonical-1 (TRPC1) ion channel as a key component of responses to hypoxia in breast cancer cells. This regulation includes control of specific epithelial to mesenchymal transition (EMT) events and hypoxia-mediated activation of signalling pathways such as activation of the EGFR, STAT3 and the autophagy marker LC3B, through hypoxia-inducible factor-1α (HIF1α)-dependent and -independent mechanisms. TRPC1 regulated HIF1α levels in PTEN-deficient MDA-MB-468 and HCC1569 breast cancer cell lines. This regulation arises from effects on the constitutive translation of HIF1α under normoxic conditions via an Akt-dependent pathway. In further support of the role of TRPC1 in EMT, its expression is closely associated with EMT- and metastasis-related genes in breast tumours, and is enhanced in basal B breast cancer cell lines. TRPC1 expression is also significantly prognostic for basal breast cancers, particularly those classified as lymph node positive. The defined roles of TRPC1 identified here could be therapeutically exploited for the control of oncogenic pathways in breast cancer cells.

Isolation, culture and identification of pulmonary arterial smooth muscle cells from rat distal pulmonary arteries

The culture of pulmonary arterial smooth muscle cells (PASMCs) is one of the most powerful tools for exploring the mechanisms of pulmonary hypertension (PH). Both pulmonary vasoconstriction and remodeling occur predominantly in distal pulmonary arteries (PA). In this study, we provide our detailed and standardized protocol for easy isolation and culture of PASMCs from rat distal PA to supply every investigator with a simple, economical and useful method in studying PH. The protocol can be divided into four stages: isolation of distal PA, isolation of cells, growth in culture and passage of cells. Rat distal PASMCs were characterized by morphological activity and by immunostaining for smooth muscle α-actin and smooth muscle myosin heavy chain, but not for CD90/Thy-1 or von Willebrand factor. Furthermore, functional assessments were performed, confirming the presence of voltage-dependent Ca²⁺ channels and physiological characteristic of response to hypoxia. In conclusion, we have developed a detailed and simple protocol for obtaining rat distal PASMCs. These PASMCs exhibit features consistent with vascular smooth muscle cells, and they could subsequently be used to further explore the pathophysiological mechanisms of PH.

Integrated RNA-seq and DNase-seq analyses identify phenotype-specific BMP4 signaling in breast cancer

Background

Bone morphogenetic protein 4 (BMP4) plays an important role in cancer pathogenesis. In breast cancer, it reduces proliferation and increases migration in a cell line-dependent manner. To characterize the transcriptional mediators of these phenotypes, we performed RNA-seq and DNase-seq analyses after BMP4 treatment in MDA-MB-231 and T-47D breast cancer cells that respond to BMP4 with enhanced migration and decreased cell growth, respectively.

Results

The RNA-seq data revealed gene expression changes that were consistent with the in vitro phenotypes of the cell lines, particularly in MDA-MB-231, where migration-related processes were enriched. These results were confirmed when enrichment of BMP4-induced open chromatin regions was analyzed. Interestingly, the chromatin in transcription start sites of differentially expressed genes was already open in unstimulated cells, thus enabling rapid recruitment of transcription factors to the promoters as a response to stimulation. Further analysis and functional validation identified MBD2, CBFB, and HIF1A as downstream regulators of BMP4 signaling. Silencing of these transcription factors revealed that MBD2 was a consistent activator of target genes in both cell lines, CBFB an activator in cells with reduced proliferation phenotype, and HIF1A a repressor in cells with induced migration phenotype.

Conclusions

Integrating RNA-seq and DNase-seq data showed that the phenotypic responses to BMP4 in breast cancer cell lines are reflected in transcriptomic and chromatin levels. We identified and experimentally validated downstream regulators of BMP4 signaling that relate to the different in vitro phenotypes and thus demonstrate that the downstream BMP4 response is regulated in a cell type-specific manner.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-016-3428-1) contains supplementary material, which is available to authorized users.

Bortezomib alleviates experimental pulmonary hypertension by regulating intracellular calcium homeostasis in PASMCs

The ubiquitin-proteasome system is considered to be the key regulator of protein degradation. Bortezomib (BTZ) is the first proteasome inhibitor approved by the US Food and Drug Administration for treatment of relapsed multiple myeloma and mantle cell lymphoma. Recently, BTZ treatment was reported to inhibit right ventricular hypertrophy and vascular remodeling in hypoxia-exposed and monocrotaline-injected rats. However, the underlying mechanisms remain poorly understood. We previously confirmed that hypoxia-elevated basal intracellular Ca(2+) concentration ([Ca(2+)]i) and store-operated Ca(2+) entry (SOCE) in pulmonary artery smooth muscle cells (PASMCs) are involved in pulmonary vascular remodeling. In this study we aim to determine whether BTZ attenuates the hypoxia-induced elevation of [Ca(2+)] in PASMCs and the signaling pathway involved in this mechanism. Our results showed that 1) in hypoxia- and monocrotaline-induced rat pulmonary hypertension (PH) models, BTZ markedly attenuated the development and progression of PH, 2) BTZ inhibited the hypoxia-induced increase in cell proliferation, basal [Ca(2+)]i, and SOCE in PASMCs, and 3) BTZ significantly normalized the hypoxia-upregulated expression of hypoxia-inducible factor-1α, bone morphogenetic protein 4, canonical transient receptor potential isoforms 1 and 6, and the hypoxia-downregulated expression of peroxisome proliferator-activated receptor-γ in rat distal pulmonary arteries and PASMCs. These results indicate that BTZ exerts its protective role in the development of PH potentially by inhibiting the canonical transient receptor potential-SOCE-[Ca(2+)]i signaling axis in PASMCs.

BMP signaling in vascular biology and dysfunction

The vascular system is critical for developmental growth, tissue homeostasis and repair but also for tumor development. Bone morphogenetic protein (BMP) signaling has recently emerged as a fundamental pathway of the endothelium by regulating cardiovascular and lymphatic development and by being causative for several vascular dysfunctions. Two vascular disorders have been directly linked to impaired BMP signaling: pulmonary arterial hypertension and hereditary hemorrhagic telangiectasia. Endothelial BMP signaling critically depends on the cellular context, which includes among others vascular heterogeneity, exposure to flow, and the intertwining with other signaling cascades (Notch, WNT, Hippo and hypoxia). The purpose of this review is to highlight the most recent findings illustrating the clear need for reconsidering the role of BMPs in vascular biology.