Long non-coding RNAs: The growth controller of vascular smooth muscle cells in cardiovascular diseases

The active proliferation and migration of vascular smooth muscle cells supports the healing of vessel damage while their abnormal aggression or destitution contribute to the aberrant intima-medial structure and function in various cardiovascular diseases, so the understanding of the proliferation disorders of vascular smooth muscle cell and the related mechanism is the basis of effective intervention and control for cardiovascular diseases. Recently, long non-coding RNAs have stood out as upstream switchers for multiple proliferative signaling pathways and molecules, and many of them have been shown to conduce to the dysregulated proliferation and apoptosis of vascular smooth muscle cells under various pathogenic stimuli. This article discusses the long non-coding RNAs disclosed and linked to atherosclerosis, pulmonary hypertension, and aneurysms, and focuses upon their modulation of vascular smooth muscle cell population affecting three deadly cardiovascular diseases.

Non-coding RNAs in human health and disease: potential function as biomarkers and therapeutic targets

Human diseases have been a critical threat from the beginning of human history. Knowing the origin, course of action and treatment of any disease state is essential. A microscopic approach to the molecular field is a more coherent and accurate way to explore the mechanism, progression, and therapy with the introduction and evolution of technology than a macroscopic approach. Non-coding RNAs (ncRNAs) play increasingly important roles in detecting, developing, and treating all abnormalities related to physiology, pathology, genetics, epigenetics, cancer, and developmental diseases. Noncoding RNAs are becoming increasingly crucial as powerful, multipurpose regulators of all biological processes. Parallel to this, a rising amount of scientific information has revealed links between abnormal noncoding RNA expression and human disorders. Numerous non-coding transcripts with unknown functions have been found in addition to advancements in RNA-sequencing methods. Non-coding linear RNAs come in a variety of forms, including circular RNAs with a continuous closed loop (circRNA), long non-coding RNAs (lncRNA), and microRNAs (miRNA). This comprises specific information on their biogenesis, mode of action, physiological function, and significance concerning disease (such as cancer or cardiovascular diseases and others). This study review focuses on non-coding RNA as specific biomarkers and novel therapeutic targets.

Insights Into the Role of Platelet-Derived Growth Factors: Implications for Parkinson’s Disease Pathogenesis and Treatment

Parkinson’s disease (PD), the second most common neurodegenerative disease after Alzheimer’s disease, commonly occurs in the elderly population, causing a significant medical and economic burden to the aging society worldwide. At present, there are few effective methods that achieve satisfactory clinical results in the treatment of PD. Platelet-derived growth factors (PDGFs) and platelet-derived growth factor receptors (PDGFRs) are important neurotrophic factors that are expressed in various cell types. Their unique structures allow for specific binding that can effectively regulate vital functions in the nervous system. In this review, we summarized the possible mechanisms by which PDGFs/PDGFRs regulate the occurrence and development of PD by affecting oxidative stress, mitochondrial function, protein folding and aggregation, Ca2+ homeostasis, and cell neuroinflammation. These modes of action mainly depend on the type and distribution of PDGFs in different nerve cells. We also summarized the possible clinical applications and prospects for PDGF in the treatment of PD, especially in genetic treatment. Recent advances have shown that PDGFs have contradictory roles within the central nervous system (CNS). Although they exert neuroprotective effects through multiple pathways, they are also associated with the disruption of the blood–brain barrier (BBB). Our recommendations based on our findings include further investigation of the contradictory neurotrophic and neurotoxic effects of the PDGFs acting on the CNS.

FGF21 alleviates pulmonary hypertension by inhibiting mTORC1/EIF4EBP1 pathway via H19

Long non‐coding RNAs (lncRNAs) play a significant role in pulmonary hypertension (PH). Our preliminary data showed that hypoxia‐induced PH is attenuated by fibroblast growth factor 21 (FGF21) administration. Therefore, we further investigated the regulatory role of long non‐coding RNAs in PH treated with FGF21. RNA sequencing analysis and real‐time PCR identified a significantly up‐regulation of the H19 after FGF21 administration. Moreover, gain‐ and loss‐of‐function assays demonstrated that FGF21 suppressed hypoxia‐induced proliferation of pulmonary artery smooth muscle cells partially through upregulation of H19. In addition, FGF21 deficiency markedly exacerbated hypoxia‐induced increases of pulmonary artery pressure and pulmonary vascular remodelling. In addition, AAV‐mediated H19 overexpression reversed the malignant phenotype of FGF21 knockout mice under hypoxia expose. Further investigation uncovered that H19 also acted as an orchestra conductor that inhibited the function of mechanistic target of rapamycin complex 1 (mTORC1) by disrupting the interaction of mTORC1 with eukaryotic translation initiation factor 4E–binding protein 1 (EIF4EBP1). Our work highlights the important role of H19 in PH treated with FGF21 and suggests a mechanism involving mTORC1/EIF4EBP1 inhibition, which may provide a fundamental for clinical application of FGF21 in PH.

MicroRNAs in Pulmonary Hypertension, from Pathogenesis to Diagnosis and Treatment

Pulmonary hypertension (PH) is a fatal and untreatable disease, ultimately leading to right heart failure and eventually death. microRNAs are small, non-coding endogenous RNA molecules that can regulate gene expression and influence various biological processes. Changes in microRNA expression levels contribute to various cardiovascular disorders, and microRNAs have been shown to play a critical role in PH pathogenesis. In recent years, numerous studies have explored the role of microRNAs in PH, focusing on the expression profiles of microRNAs and their signaling pathways in pulmonary artery smooth muscle cells (PASMCs) or pulmonary artery endothelial cells (PAECs), PH models, and PH patients. Moreover, certain microRNAs, such as miR-150 and miR-26a, have been identified as good candidates of diagnosis biomarkers for PH. However, there are still several challenges for microRNAs as biomarkers, including difficulty in normalization, specificity in PH, and a lack of longitudinal and big sample-sized studies. Furthermore, microRNA target drugs are potential therapeutic agents for PH treatment, which have been demonstrated in PH models and in humans. Nonetheless, synthetic microRNA mimics or antagonists are susceptible to several common defects, such as low drug efficacy, inefficient drug delivery, potential toxicity and especially, off-target effects. Therefore, finding clinically safe and effective microRNA drugs remains a great challenge, and further breakthrough is urgently needed.

LncPTSR Triggers Vascular Remodeling in Pulmonary Hypertension by Regulating [Ca2+]i in Pulmonary Arterial Smooth Muscle Cells

Pulmonary hypertension (PH) is characterized by vascular remodeling and sustained increase in right ventricular systolic pressure (RVSP). The molecular mechanisms behind PH development remain unclear. Here, a long non-coding RNA (lncRNA) attenuated by platelet-derived growth factor BB (PDGF-BB) was identified and its functional roles were investigated in vitro and in vivo. Using RNA-seq data and rapid amplification of cDNA ends, a lncRNA neighboring the locus of plasma membrane calcium transporting ATPase 4 (PMCA4) was identified and named lncPTSR. It is a highly-conserved nuclear lncRNA, and was downregulated in pulmonary arterial smooth muscle cells (PASMCs) with PDGF-BB stimulation or hypoxia induction. Gene interruption/overexpression assays revealed that lncPTSR negatively regulates rat PASMCs proliferation, apoptosis, and migration. LncPTSR interruption in Sprague Dawley (SD) rats using adenovirus associated virus type 9 (AAV9)-mediated short-hairpin RNA (shRNA) resulted in a significant increase in RVSP and vascular remodeling in normoxic condition. LncPTSR knockdown also suppressed PMCA4 expression and attenuated the intracellular Ca2+ efflux of PASMCs in vitro and in vivo. Further studies suggest a complex cross-talk between lncPTSR and mitogen-activated protein kinase (MAPK) pathway: inhibition of mitogen-activated protein kinase kinase (MEK) and extracellular signal-regulated kinase (ERK) abolishes the PDGF-BB-mediated lncPTSR downregulation, and lncPTSR plays a feedback regulation for MAPK signaling molecules. The present study suggests that lncPTSR participates in pulmonary artery (PA) remodeling via modulating the expression of PMCA4 and intracellular Ca2+ homeostasis downstream of PDGF-BB driven MEK/ERK signaling. These results suggest lncPTSR may be a promising therapeutic target in PH treatment.

hsa_circWDR37_016 Regulates Hypoxia-Induced Proliferation of Pulmonary Arterial Smooth Muscle Cells

Pulmonary arterial hypertension (PAH) is characterized by abnormal remodeling of pulmonary vessel walls caused by excessive pulmonary arterial smooth muscle cell (PASMC) proliferation. Our previous clinical studies have demonstrated the importance of the downregulated circRNA in PAH. However, the role of upregulated circRNAs is still elusive. Here, we identified the upregulated circRNA in PAH patients, hsa_circWDR37_016 (circWDR37), as a key regulator of hypoxic proliferative disorder of pulmonary arterial smooth muscle cells (PASMCs). Quantitative real-time PCR (qRT-PCR) analysis validated that exposure to hypoxia markedly increased the circWDR37 level in cultured human PASMCs. As evidenced by flow cytometry, 5-ethynyl-2′-deoxyuridine (EdU) incorporation, wound healing, and Tunel assay, silencing of endogenous circWDR37 attenuated proliferation and cell-cycle progression in hypoxia-exposed human PASMCs in vitro. Furthermore, bioinformatics and Luciferase assay showed that circWDR37 directly sponged hsa-miR-138-5p (miR-138) and was involved in the immunoregulatory and inflammatory processes of PAH. Together, these studies suggested new insights into circRNA regulated the pathology of PAH, providing a new potential therapeutic target for PAH treatment.

Epigenetic Mechanisms as Emerging Therapeutic Targets and Microfluidic Chips Application in Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a disease that progress over time and is defined as an increase in pulmonary arterial pressure and pulmonary vascular resistance that frequently leads to right-ventricular (RV) failure and death. Epigenetic modifications comprising DNA methylation, histone remodeling, and noncoding RNAs (ncRNAs) have been established to govern chromatin structure and transcriptional responses in various cell types during disease development. However, dysregulation of these epigenetic mechanisms has not yet been explored in detail in the pathology of pulmonary arterial hypertension and its progression with vascular remodeling and right-heart failure (RHF). Targeting epigenetic regulators including histone methylation, acetylation, or miRNAs offers many possible candidates for drug discovery and will no doubt be a tempting area to explore for PAH therapies. This review focuses on studies in epigenetic mechanisms including the writers, the readers, and the erasers of epigenetic marks and targeting epigenetic regulators or modifiers for treatment of PAH and its complications described as RHF. Data analyses from experimental cell models and animal induced PAH models have demonstrated that significant changes in the expression levels of multiple epigenetics modifiers such as HDMs, HDACs, sirtuins (Sirt1 and Sirt3), and BRD4 correlate strongly with proliferation, apoptosis, inflammation, and fibrosis linked to the pathological vascular remodeling during PAH development. The reversible characteristics of protein methylation and acetylation can be applied for exploring small-molecule modulators such as valproic acid (HDAC inhibitor) or resveratrol (Sirt1 activator) in different preclinical models for treatment of diseases including PAH and RHF. This review also presents to the readers the application of microfluidic devices to study sex differences in PAH pathophysiology, as well as for epigenetic analysis.

Role of Long Non-Coding RNAs in Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a debilitating condition of the pulmonary circulatory system that occurs in patients of all ages and if untreated, eventually leads to right heart failure and death. Despite existing medical treatment options that improve survival and quality of life, the disease remains incurable. Thus, there is an urgent need to develop novel therapies to treat this disease. Emerging evidence suggests that long non-coding RNAs (lncRNAs) play critical roles in pulmonary vascular remodeling and PAH. LncRNAs are implicated in pulmonary arterial endothelial dysfunction by modulating endothelial cell proliferation, angiogenesis, endothelial mesenchymal transition, and metabolism. LncRNAs are also involved in inducing different pulmonary arterial vascular smooth muscle cell phenotypes, such as cell proliferation, apoptosis, migration, regulation of the phenotypic switching, and cell cycle. LncRNAs are essential regulators of gene expression that affect various diseases at the chromatin, transcriptional, post-translational, and even post-translational levels. Here, we focus on the role of LncRNAs and their molecular mechanisms in the pathogenesis of PAH. We also discuss the current research challenge and potential biomarker and therapeutic potentials of lncRNAs in PAH.

LncRNA HCG11 Inhibits Adipocyte Differentiation in Human Adipose-Derived Mesenchymal Stem Cells by Sponging miR-204-5p to Upregulate SIRT1

Long noncoding RNAs (lncRNAs) have been discovered to play a key role in adipogenesis, while the role of lncRNA human leukocyte antigen complex group 11 (HCG11) in adipocyte differentiation has not been studied clearly. We used human adipose-derived mesenchymal stem cells (hAdMSCs) to establish a model of cell differentiation in vitro and found that expression of lncRNA HCG11 was decreased during adipogenesis through real-time quantitative polymerase chain reaction analysis. Then, hAdMSCs were transfected with pcDNA-HCG11 or HCG11-shRNA (sh-HCG11); the adipogenic marker proteins were detected by Western blot, and the activity of lipogenesis enzymes was detected by spectrophotometry. The expression of CCAAT-enhancer-binding protein α, fatty acid-binding protein, peroxisome proliferator-activated receptor gamma 2 and the levels of acetyl coenzyme A carboxylase and fatty acid synthase FAS were significantly downregulated in hAdMSCs at different stages transfected with pcDNA-HCG11, while knockdown of lncRNA HCG11 promoted adipocyte differentiation. Bioinformatic analysis indicated that miR-204-5p was a potential target gene of HCG11, which was confirmed by luciferase reporter gene analysis and RNA pull-down analysis. In addition, miR-204-5p directly targeting the 3′-untranslated region of SIRT1 was also predicted by StarBase and verified by luciferase reporter gene analysis. Enforced expression of miR-204-5p negatively regulated the SIRT1 protein level. Furthermore, SIRT1 overexpression significantly inhibited adipogenic marker protein, levels of lipogenesis enzymes, and the proliferation of hAdMSCs. When pcDNA-HCG11 and miR-204-5p mimic were co-transfected into hAdMSCs, we found that the miR-204-5p mimic reversed the suppressor effect of pcDNA-HCG11. Taken together, we found that HCG11 negatively regulated cell proliferation and adipogenesis by the miR-204-5p/SIRT1 axis. Our findings might provide a new target for the study of adipogenesis in hAdMSCs and obesity.

Novel molecular insights and public omics data in pulmonary hypertension

Pulmonary hypertension is a rare disease with high morbidity and mortality which mainly affects women of reproductive age. Despite recent advances in understanding the pathogenesis of pulmonary hypertension, the high heterogeneity in the presentation of the disease among different patients makes it difficult to make an accurate diagnosis and to apply this knowledge to effective treatments. Therefore, new studies are required to focus on translational and personalized medicine to overcome the lack of specificity and efficacy of current management. Here, we review the majority of public databases storing 'omics' data of pulmonary hypertension studies, from animal models to human patients. Moreover, we review some of the new molecular mechanisms involved in the pathogenesis of pulmonary hypertension, including non-coding RNAs and the application of 'omics' data to understand this pathology, hoping that these new approaches will provide insights to guide the way to personalized diagnosis and treatment.

Chronic hypoxia promoted pulmonary arterial smooth muscle cells proliferation through upregulated calcium-sensing receptorcanonical transient receptor potential 1/6 pathway

OBJECTIVES

Although both calcium-sensing receptor (CaSR) and canonical transient receptor potential (TRPC) proteins contribute to chronic hypoxia (CH)-induced pulmonary arterial smooth muscle cells (PASMCs) proliferation, the relationship between CaSR and TRPC in hypoxic PASMCs proliferation remains poorly understood. The goal of this study was to identify that CH promotes PASMCs proliferation through CaSR-TRPC pathway.

METHODS

Rat PASMCs were isolated and treated with CH. Cell proliferation was assessed by cell counting, CCK-8 assay, and EdU incorporation. CaSR and TRPC expressions were determined by qPCR and Western blotting. Store-operated Ca²⁺ entry (SOCE) was assessed by extracellular Ca²⁺ restoration.

RESULTS

In PASMCs, CH enhanced the cell number, cell viability and DNA synthesis, which is accompanied by upregulated expression of CaSR, TRPC1 and TRPC6. Negative CaSR modulators (NPS2143, NPS2390) inhibited, whereas positive modulators (spermine, R568) enhanced, the CH-induced increases in cell number, cell viability and DNA synthesis in PASMCs. Knockdown of CaSR by siRNA inhibited the CH-induced upregulation of TRPC1 and TRPC6 and enhancement of SOCE and attenuated the CH-induced enhancements of cell number, cell viability and DNA synthesis in PASMCs. However, neither siTRPC1 nor siTRPC6 had an effect on the CH-induced CaSR upregulation, although both significantly attenuated the CH-induced enhancements of cell number, cell viability and DNA synthesis in PASMCs.

CONCLUSION

These results demonstrate that upregulated CaSR-TRPC1/6 pathway mediating PASMCs proliferation is an important pathogenic mechanism under hypoxic conditions.

The lncRNA PAHRF functions as a competing endogenous RNA to regulate MST1 expression by sponging miR-23a-3p in pulmonary arterial hypertension

BACKGROUND

Emerging evidence has shown that long non-coding RNA (lncRNA) plays important roles in the development of pulmonary arterial hypertension (PAH). However, some new lncRNAs in patients with PAH are still lacking research. Herein, we examined the expression and role of lncRNA (pulmonary arterial hypertension related factor, PAHRF) in PAH.

METHODS

LncRNA PAHRF expression and localization were analyzed by realtime PCR and fluorescence in situ hybridization. Proliferation and apoptosis were detected by MTT, CCK-8, EDU staining, JC-1 assay, flow cytometry and western blotting. Luciferase activity assay was used to identify PAHRF/ miR-23a-3p/serine/threonine kinase 4 (STK4/MST1) interaction.

RESULTS

LncRNA PAHRF was down-regulated in both the PAs of PAH patients and hypoxic human pulmonary artery smooth muscle cells (PASMCs). The overexpression of PAHRF inhibited the proliferation and promoted the apoptosis of PASMCs. Similarly, we also found PAHRF overexpression decreased the proliferation under hypoxia condition. Knockdown of PAHRF exerted the opposite effects. Luciferase activity assay proved molecular binding between PAHRF and hsa-miR-23a-3p. Moreover, MST1 was confirmed to be the putative target gene and regulated by PAHRF/miR-23a-3p. In addition, we explored the molecular mechanism regulating the expression of miR-23a-3p, and found that lncRNA PAHRF acted as an endogenous sponge for miR-23a-3p, and silencing lncRNA PAHRF could up-regulate the expression of miR-23a-3p. On the contrary, PAHRF-overexpressing plasmid inhibited the expression of miR-23a-3p in hypoxia.

CONCLUSIONS

Our present study reveals a novel PAH regulating model that is composed of PAHRF, miR-23a-3p, and MST1. The aim of this study is probably going to provide a new explanation and give a further understanding of the occurrence of vascular remodeling in PAH from the perspective competing endogenous RNA hypothesis.

LINC01559 promotes colorectal cancer via sponging miR-1343-3p to modulate PARP1/PTEN/AKT pathway

BACKGROUND

Colorectal cancer (CRC) is considered as one of the commonest tumors and is the major reason of cancer-related deaths around the world. Plentiful evidences have validated that long non-coding RNAs (lncRNAs) play a significant part in various cancers, including CRC. LINC01559 is implicated in the development of various cancers. However, the detailed function of LINC01559 in CRC has not been illustrated.

METHODS

LINC01559 expression was examined via RT-qPCR, and a series of functional experiments were conducted to explore the role of LINC01559 in CRC progression. Mechanism experiments were carried out to examine the underlying mechanism of LINC01559.

RESULTS

LINC01559 expression was increased in CRC cells and tissues, and LINC01559 depletion restrained the biological behaviors of CRC cells. Also, LINC01559 sponged miR-1343-3p in CRC, and PARP1 was the target of miR-1343-3p. Besides, miR-1343-3p overexpression or PARP1 down-regulation affected the biological behaviors of CRC cells. In addition, up-regulation of PARP1 or adding SC79 (AKT pathway activator) could remedy the repressive effects of LINC01559 silencing on CRC cell biological behaviors.

CONCLUSIONS

LINC01559 promotes CRC through sponging miR-1343-3p to modulate PARP1/PTEN/AKT pathway, which may be conducive to offering a new idea for CRC therapeutic treatment.

Evolving Schema for Employing Network Biology Approaches to Understand Pulmonary Hypertension

Reductionist approaches have served as the cornerstone for traditional mechanistic endeavors in biomedical research. However, for pulmonary hypertension (PH), a relatively rare but deadly vascular disease of the lungs, the use of traditional reductionist approaches has failed to define the complexities of pathogenesis. With the development of new -omics platforms (i.e., genomics, transcriptomics, proteomics, and metabolomics, among others), network biology approaches have offered new pipelines for discovery of human disease pathogenesis. Human disease processes are driven by multiple genes that are dysregulated which are affected by regulatory networks. Network theory allows for the identification of such gene clusters which are dysregulated in various disease states. This framework may in part explain why current therapeutics that seek to target a single part of a dysregulated cluster may fail to provide clinically significant improvements. Correspondingly, network biology could further the development of novel therapeutics which target clusters of "disease genes" so that a disease phenotype can be more robustly addressed. In this chapter, we seek to explain the theory behind network biology approaches to identify drivers of disease as well as how network biology approaches have been used in the field of PH. Furthermore, we discuss an example of in silico methodology using network pharmacology in conjunction with gene networks tools to identify drugs and drug targets. We discuss similarities between the pathogenesis of PH and other disease states, specifically cancer, and how tools developed for cancer may be repurposed to fill the gaps in research in PH. Finally, we discuss new approaches which seek to integrate clinical health record data into networks so that correlations between disease genes and clinical parameters can be explored in the context of this disease.

PDGF/MEK/ERK axis represses Ca2+ clearance via decreasing the abundance of plasma membrane Ca2+ pump PMCA4 in pulmonary arterial smooth muscle cells

Pulmonary arterial hypertension (PAH) is a rare and lethal disease characterized by vascular remodeling and vasoconstriction, which is associated with increased intracellular calcium ion concentration ([Ca2+]i). Platelet-derived growth factor-BB (PDGF-BB) is the most potent mitogen for pulmonary arterial smooth muscle cells (PASMCs) and is involved in vascular remodeling during PAH development. PDGF signaling has been proved to participate in maintaining Ca2+ homeostasis of PASMCs; however, the mechanism needs to be further elucidated. Here, we illuminate that the expression of plasma membrane calcium-transporting ATPase 4 (PMCA4) was downregulated in PASMCs after PDGF-BB stimulation, which could be abolished by restraining the mitogen-activated protein kinase/extracellular signal-regulated kinase (MEK/ERK). Functionally, suppression of PMCA4 attenuated the [Ca2+]i clearance in PASMCs after Ca2+ entry, promoting cell proliferation and elevating cell locomotion through mediating formation of focal adhesion. Additionally, the expression of PMCA4 was decreased in the pulmonary artery of monocrotaline (MCT)- or hypoxia-induced PAH rats. Moreover, knockdown of PMCA4 could increase the right ventricular systolic pressure (RVSP) and wall thickness (WT) of pulmonary artery in rats raised under normal conditions. Taken together, our findings demonstrate the importance of the PDGF/MEK/ERK/PMCA4 axis in intracellular Ca2+ homeostasis in PASMCs, indicating a functional role of PMCA4 in pulmonary arterial remodeling and PAH development.

Epigenetic Targets for Oligonucleotide Therapies of Pulmonary Arterial Hypertension

Arterial wall remodeling underlies increased pulmonary vascular resistance and right heart failure in pulmonary arterial hypertension (PAH). None of the established vasodilator drug therapies for PAH prevents or reverse established arterial wall thickening, stiffening, and hypercontractility. Therefore, new approaches are needed to achieve long-acting prevention and reversal of occlusive pulmonary vascular remodeling. Several promising new drug classes are emerging from a better understanding of pulmonary vascular gene expression programs. In this review, potential epigenetic targets for small molecules and oligonucleotides will be described. Most are in preclinical studies aimed at modifying the growth of vascular wall cells in vitro or normalizing vascular remodeling in PAH animal models. Initial success with lung-directed delivery of oligonucleotides targeting microRNAs suggests other epigenetic mechanisms might also be suitable drug targets. Those targets include DNA methylation, proteins of the chromatin remodeling machinery, and long noncoding RNAs, all of which act as epigenetic regulators of vascular wall structure and function. The progress in testing small molecules and oligonucleotide-based drugs in PAH models is summarized.

'There and Back Again'-Forward Genetics and Reverse Phenotyping in Pulmonary Arterial Hypertension

Although the invention of right heart catheterisation in the 1950s enabled accurate clinical diagnosis of pulmonary arterial hypertension (PAH), it was not until 2000 when the landmark discovery of the causative role of bone morphogenetic protein receptor type II (BMPR2) mutations shed new light on the pathogenesis of PAH. Since then several genes have been discovered, which now account for around 25% of cases with the clinical diagnosis of idiopathic PAH. Despite the ongoing efforts, in the majority of patients the cause of the disease remains elusive, a phenomenon often referred to as "missing heritability". In this review, we discuss research approaches to uncover the genetic architecture of PAH starting with forward phenotyping, which in a research setting should focus on stable intermediate phenotypes, forward and reverse genetics, and finally reverse phenotyping. We then discuss potential sources of "missing heritability" and how functional genomics and multi-omics methods are employed to tackle this problem.

Emerging role of long non-coding RNAs in pulmonary hypertension and their molecular mechanisms (Review)

Pulmonary hypertension (PH) is a life-threatening cardiopulmonary condition caused by several pathogenic factors. All types of PH are characterized by the excessive proliferation of pulmonary artery endothelial cells and pulmonary artery smooth muscle cells, apoptosis resistance, pulmonary vascular remodeling, sustained elevated pulmonary arterial pressure, right heart failure and even death. Over the past decade, next generation sequencing, particularly RNA-sequencing, has identified some long non-coding RNAs (lncRNAs) that may act as regulators of cell differentiation, proliferation and apoptosis. Studies have shown that lncRNAs are closely associated with the development of several diseases, including cardiovascular diseases. In addition, a number of studies have reported that lncRNAs, including maternally expressed gene 3, metastasis-associated lung adenocarcinoma transcript 1, taurine upregulated 1 and cancer susceptibility candidate 2, serve important roles in the pathogenesis of PH. Despite the development of novel drug treatments, the mortality rate of PH remains high with no evident downward trend. Therefore, certain lncRNAs may be considered as therapeutic targets for the treatment of incurable PH. The present review summarizes the latest research on lncRNAs and PH, aiming to briefly describe PH-associated lncRNAs and their mechanisms of action.

Beyond the genome: challenges and potential for epigenetics-driven therapeutic approaches in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a devastating disease of the cardiopulmonary system caused by the narrowing of the pulmonary arteries, leading to increased vascular resistance and pressure. This leads to right ventricle remodeling, dysfunction, and eventually, death. While conventional therapies have largely focused on targeting vasodilation, other pathological features of PAH including aberrant inflammation, mitochondrial dynamics, cell proliferation, and migration have not been well explored. Thus, despite some recent improvements in PAH treatment, the life expectancy and quality of life for patients with PAH remains poor. Showing many similarities to cancers, PAH is characterized by increased pulmonary arterial smooth muscle cell proliferation, decreased apoptotic signaling pathways, and changes in metabolism. The recent successes of therapies targeting epigenetic modifiers for the treatment of cancer has prompted epigenetic research in PAH, revealing many new potential therapeutic targets. In this minireview we discuss the emergence of epigenetic dysregulation in PAH and highlight epigenetic-targeting compounds that may be effective for the treatment of PAH.

Overexpressed lncRNA AC068039.4 Contributes to Proliferation and Cell Cycle Progression of Pulmonary Artery Smooth Muscle Cells Via Sponging miR-26a-5p/TRPC6 in Hypoxic Pulmonary Arterial Hypertension

BACKGROUND

Hypoxic pulmonary hypertension (HPH) is a devastating and incurable disease characterized by pulmonary vascular remodeling, resulting in right heart failure and even death. Accumulated evidence has confirmed long coding RNAs (lncRNAs) are involved in hypoxia-induced pulmonary vascular remodeling in HPH. The exact mechanism of lncRNA in hypoxic pulmonary hypertension remains unclear.

METHODS

Microarray analysis was applied to investigate the profiles of lncRNA expression in pulmonary artery smooth muscle cells (PASMCs) cultured under hypoxia and normoxia condition. qRT-PCR was performed for the expression of lncRNAs, miRNA, and mRNAs, western blot analysis was employed for the detection of the expression of proteins. CCK-8 and transwell chamber assay were applied for the assessment of PASMC proliferation and migration, respectively. Besides, flow cytometry was performed for assessments of cell cycle progression. The binding between AC068039.4 and miR-26a-5p, miR-26a-5p, and TRPC6 3'UTR was detected by dual luciferase reporter assay.

RESULTS

A total of 1,211 lncRNAs (698 up-regulated and 513 down-regulated) were differently expressed in hypoxia-induced PASMCs. Consistent with microarray analysis, quantitative PCR verified that AC068039.4 was obviously up-regulated in hypoxia-induced PASMCs. Knocking down AC068039.4 alleviated proliferation and migration of PASMCs and regulated cell cycle progression through inhibiting cells entering the G0/G1 cell cycle phase. Further experiment indicated AC068039.4 promoted hypoxic PASMCs proliferation via sponging miR-26-5p. In addition, transient receptor potential canonical 6 (TRPC6) was confirmed to be a target gene of miR-26a-5p.

CONCLUSION

In conclusion, downregulation of lncRNA AC068039.4 inhibited pulmonary vascular remodeling through AC068039.4/miR-26a-5p/TRPC6 axis, providing new therapeutic insights for the treatment of HPH.

The application of 'omics' to pulmonary arterial hypertension

Recent genome-wide analyses of rare and common sequence variations have brought greater clarity to the genetic architecture of pulmonary arterial hypertension and implicated novel genes in disease development. Transcriptional signatures have been reported in whole lung tissue, pulmonary vascular cells and peripheral circulating cells. High-throughput platforms for plasma proteomics and metabolomics have identified novel biomarkers associated with clinical outcomes and provided molecular instruments for risk assessment. There are methodological challenges to integrating these datasets, coupled to statistical power limitations inherent to the study of a rare disease, but the expectation is that this approach will reveal novel druggable targets and biomarkers that will open the way to personalized medicine. Here, we review the current state-of-the-art and future promise of 'omics' in the field of translational medicine in pulmonary arterial hypertension. LINKED ARTICLES: This article is part of a themed issue on Risk factors, comorbidities, and comedications in cardioprotection. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.1/issuetoc.

Long Noncoding RNA COPDA1 Promotes Airway Smooth Muscle Cell Proliferation in Chronic Obstructive Pulmonary Disease

Abnormal expression of long noncoding RNAs (lncRNAs) has been confirmed to be associated with many diseases, including chronic obstructive pulmonary disease (COPD). To gain better understanding of the mechanism of COPD, we investigated the lncRNA and mRNA profiles in the lung tissue of patients with COPD. According to the analysis, one of the significantly different lncRNAs, COPDA1, might participate in the occurrence and development of COPD. Lung tissues were collected from nonsmokers, smokers, or smokers with COPD for RNA sequencing. Bioinformatic analysis and cell experiments were used to define the function of COPDA1, and the effects of COPDA1 on intracellular Ca²⁺ concentration and cell proliferation were examined after knockdown or overexpression of COPDA1. A number of variations of lncRNAs were found in the comparison of nonsmokers, smokers, and smokers with COPD. GO (Gene Ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway analyses indicated that smoking was involved in the activation of cytokines and the cell cycle, which is associated with COPD. According to the lncRNA-mRNA-coexpressing network and enrichment analysis, COPDAz1 and one of its target genes, MS4A1 (membrane-spanning 4-domains family, subfamily A) were investigated, and we discovered that the expression of MS4A1 was closely associated with lncRNA COPDA1 expression in human bronchial smooth muscle cells (HBSMCs). Further study showed that lncRNA COPDA1 upregulated the expression of MS4A1 to increase store-operated calcium entry in the HBSMCs, resulting in the promotion of the proliferation of smooth muscle cells as well as of airway remodeling. COPDA1 might be involved in the regulation of certain signaling pathways in COPD, might promote the proliferation of HBSMCs, and might also be involved in facilitating airway remodeling.

Pathobiology of pulmonary artery hypertension: role of long non-coding RNAs

Pulmonary arterial hypertension (PAH) is a disease with complex pathobiology, significant morbidity and mortality, and remains without a cure. It is characterized by vascular remodelling associated with uncontrolled proliferation of pulmonary artery smooth muscle cells, endothelial cell proliferation and dysfunction, and endothelial-to-mesenchymal transition, leading to narrowing of the vascular lumen, increased vascular resistance and pulmonary arterial pressure, which inevitably results in right heart failure and death. There are multiple molecules and signalling pathways that are involved in the vascular remodelling, including non-coding RNAs, i.e. microRNAs and long non-coding RNAs (lncRNAs). It is only in recent years that the role of lncRNAs in the pathobiology of pulmonary vascular remodelling and right ventricular dysfunction is being vigorously investigated. In this review, we have summarized the current state of knowledge about the role of lncRNAs as key drivers and gatekeepers in regulating major cellular and molecular trafficking involved in the pathogenesis of PAH. In addition, we have discussed the limitations and challenges in translating lncRNA research in vivo and in therapeutic applications of lncRNAs in PAH.

Long noncoding RNAs as novel players in the pathogenesis of hypertension

Long noncoding RNAs (lncRNAs) are non-(protein)-coding RNAs longer than ~200 nucleotides and have been reported to be involved in multiple human diseases by regulating gene expression. A growing body of evidence has demonstrated that lncRNAs are also widely implicated in mechanisms of hypertension, including regulation of the proliferation, migration, and apoptosis of VSMCs; the production of iNOS and NO; and the angiogenic function of endothelial cells. Several lncRNAs were also differentially expressed in the renal and cardiac tissues of hypertensive rats and even in placental samples from preeclampsia patients. In particular, several circulating lncRNAs have been identified as novel biomarkers of hypertension. In this review, we summarize the current studies of lncRNAs in the pathogenesis of hypertension in order to aid in better understanding the molecular mechanism of hypertension and provide a basis to explore new therapeutic targets.

Targeting epigenetic mechanisms as an emerging therapeutic strategy in pulmonary hypertension disease

Pulmonary arterial hypertension (PAH) is a multifactorial cardiopulmonary disease characterized by an elevation of pulmonary artery pressure (PAP) and pulmonary vascular resistance (PVR), which can lead to right ventricular (RV) failure, multi-organ dysfunction, and ultimately to premature death. Despite the advances in molecular biology, the mechanisms underlying pulmonary hypertension (PH) remain unclear. Nowadays, there is no curative treatment for treating PH. Therefore, it is crucial to identify novel, specific therapeutic targets and to offer more effective treatments against the progression of PH. Increasing amounts of evidence suggest that epigenetic modification may play a critical role in the pathogenesis of PAH. In the presented paper, we provide an overview of the epigenetic mechanisms specifically, DNA methylation, histone acetylation, histone methylation, and ncRNAs. As the recent identification of new pharmacological drugs targeting these epigenetic mechanisms has opened new therapeutic avenues, we also discuss the importance of epigenetic-based therapies in the context of PH.

Linking lncRNAs to regulation, pathogenesis, and diagnosis of pulmonary hypertension

Pulmonary hypertension (PH) is a syndrome characterized by a persistent increase in pulmonary vascular resistance. Due to the lack of specificity in clinical manifestations, patients are usually diagnosed at the late stage of PH, which is hard to treat and often causes right heart failure and death. Furthermore, the regulation and pathogenesis of PH remain obscure. Recently, long noncoding RNAs (lncRNAs), a type of transcript longer than 200 nt that lacks protein-coding ability, have been found to substantially influence the incidence and progression of various diseases through regulating gene expression at the chromatin, transcriptional, post-transcriptional, translational, and even post-translational levels. The crucial roles of lncRNAs in PH have started to draw widespread attention. This review summarizes the regulatory, pathogenic, and diagnostic roles of lncRNAs in PH, in the hope to facilitate the search for early diagnostic markers of and effective therapeutic targets for this devastating disease.

Clinical value of non-coding RNAs in cardiovascular, pulmonary, and muscle diseases

Although a majority of the mammalian genome is transcribed to RNA, mounting evidence indicates that only a minor proportion of these transcriptional products are actually translated into proteins. Since the discovery of the first non-coding RNA (ncRNA) in the 1980s, the field has gone on to recognize ncRNAs as important molecular regulators of RNA activity and protein function, knowledge of which has stimulated the expansion of a scientific field that quests to understand the role of ncRNAs in cellular physiology, tissue homeostasis, and human disease. Although our knowledge of these molecules has significantly improved over the years, we have limited understanding of their precise functions, protein interacting partners, and tissue-specific activities. Adding to this complexity, it remains unknown exactly how many ncRNAs there are in existence. The increased use of high-throughput transcriptomics techniques has rapidly expanded the list of ncRNAs, which now includes classical ncRNAs (e.g., ribosomal RNAs and transfer RNAs), microRNAs, and long ncRNAs. In addition, splicing by-products of protein-coding genes and ncRNAs, so-called circular RNAs, are now being investigated. Because there is substantial heterogeneity in the functions of ncRNAs, we have summarized the present state of knowledge regarding the functions of ncRNAs in heart, lungs, and skeletal muscle. This review highlights the pathophysiologic relevance of these ncRNAs in the context of human cardiovascular, pulmonary, and muscle diseases.

MicroRNAs and Long Non-coding RNAs in Genetic Diseases

Since the discovery and classification of non-coding RNAs, their roles have gained great attention. In this respect, microRNAs and long non-coding RNAs have been firmly demonstrated to be linked to regulation of gene expression and onset of human diseases, including rare genetic diseases; therefore they are suitable targets for therapeutic intervention. This issue, in the context of rare genetic diseases, is being considered by an increasing number of research groups and is of key interest to the health community. In the case of rare genetic diseases, the possibility of developing personalized therapy in precision medicine has attracted the attention of researchers and clinicians involved in developing "orphan medicinal products" and proposing these to the European Medicines Agency (EMA) and to the Food and Drug Administration (FDA) Office of Orphan Products Development (OOPD) in the United States. The major focuses of these activities are the evaluation and development of products (drugs, biologics, devices, or medical foods) considered to be promising for diagnosis and/or treatment of rare diseases or conditions, including rare genetic diseases. In an increasing number of rare genetic diseases, analysis of microRNAs and long non-coding RNAs has been proven a promising strategy. These diseases include, but are not limited to, Duchenne muscular dystrophy, cystic fibrosis, Rett syndrome, and β-thalassemia. In conclusion, a large number of approaches based on targeting microRNAs and long non-coding RNAs are expected in the field of molecular diagnosis and therapy, with a facilitated technological transfer in the case of rare genetic diseases, in virtue of the existing regulation concerning these diseases.

Long non-coding RNA in osteogenesis: A new world to be explored

Long non-coding RNAs (lncRNAs) are transcripts longer than 200 nucleotides with limited coding potential, which have emerged as novel regulators in many biological and pathological processes, including growth, development, and oncogenesis. Accumulating evidence suggests that lncRNAs have a special role in the osteogenic differentiation of various types of cell, including stem cells from different sources such as embryo, bone marrow, adipose tissue and periodontal ligaments, and induced pluripotent stem cells. Involved in complex mechanisms, lncRNAs regulate osteogenic markers and key regulators and pathways in osteogenic differentiation. In this review, we provide insights into the functions and molecular mechanisms of lncRNAs in osteogenesis and highlight their emerging roles and clinical value in regenerative medicine and osteogenesis-related diseases.

Cite this article: J. Zhang, X. Hao, M. Yin, T. Xu, F. Guo. Long non-coding RNA in osteogenesis: A new world to be explored. Bone Joint Res 2019;8:73–80. DOI: 10.1302/2046-3758.82.BJR-2018-0074.R1.

Long noncoding RNA Hoxaas3 contributes to hypoxia-induced pulmonary artery smooth muscle cell proliferation

Aims

Long noncoding RNAs (lncRNAs) are involved in the regulation of vascular smooth muscle cells and cardiovascular pathology. However, the contribution of lncRNAs to pulmonary hypertension (PH) remains largely unknown. The over-proliferation of pulmonary artery smooth muscle cells (PASMCs) causes pulmonary arterial smooth muscle hypertrophy and stenosis of the pulmonary vascular lumen, resulting in PH. Here, we investigated the biological role of a novel lncRNA, Hoxa cluster antisense RNA 3 (Hoxaas3), in the regulation of cell proliferation in PH.

Methods and results

Hoxaas3 was up-regulated in the lung vasculature of hypoxic mice and in PASMCs under hypoxic conditions. Histone H3 Lysine 9 acetylation of Hoxaas3 promoted gene expression. Moreover, high expression of Hoxaas3 was associated with cell proliferation and modulated cell cycle distribution by up-regulating Homeobox a3 at the mRNA and protein levels.

Conclusion

This study defined the role and mechanism of action of Hoxaas3 in the regulation of cell proliferation in PH, which should facilitate the development of new therapeutic strategies for the treatment of this disease.

Long non-coding RNAs influence the transcriptome in pulmonary arterial hypertension: the role of PAXIP1-AS1

In idiopathic pulmonary arterial hypertension (IPAH), global transcriptional changes induce a smooth muscle cell phenotype characterised by excessive proliferation, migration, and apoptosis resistance. Long non‐coding RNAs (lncRNAs) are key regulators of cellular function. Using a compartment‐specific transcriptional profiling approach, we sought to investigate the link between transcriptional reprogramming by lncRNAs and the maladaptive smooth muscle cell phenotype in IPAH. Transcriptional profiling of small remodelled arteries from 18 IPAH patients and 17 controls revealed global perturbations in metabolic, neuronal, proliferative, and immunological processes. We demonstrated an IPAH‐specific lncRNA expression profile and identified the lncRNA PAXIP1‐AS1 as highly abundant. Comparative transcriptomic analysis and functional assays revealed an intrinsic role for PAXIP1‐AS1 in orchestrating the hyperproliferative and migratory actions of IPAH smooth muscle cells. Further, we showed that PAXIP1‐AS1 mechanistically interferes with the focal adhesion axis via regulation of expression and phosphorylation of its downstream target paxillin. Overall, we show that changes in the lncRNA transcriptome contribute to the disease‐specific transcriptional landscape in IPAH. Our results suggest that lncRNAs, such as PAXIP1‐AS1, can modulate smooth muscle cell function by affecting multiple IPAH‐specific transcriptional programmes. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

LncRNA H19 promotes the proliferation of pulmonary artery smooth muscle cells through AT1R via sponging let-7b in monocrotaline-induced pulmonary arterial hypertension

BACKGROUND

Pulmonary arterial hypertension (PAH) is related to inflammation, and the lncRNA H19 is associated with inflammation. However, whether PDGF-BB-H19-let-7b-AT1R axis contributes to the pathogenesis of PAH has not been thoroughly elucidated to date. This study investigated the role of H19 in PAH and its related mechanism.

METHODS

In the present study, SD rats, C57/BL6 mice and H19-/- mice were injected with monocrotaline (MCT) to establish a PAH model. H19 was detected in the cytokine-stimulated pulmonary arterial smooth muscle cells (PASMCs), serum and lungs of rats/mice. H19 overexpression and knockdown experiments were also conducted. A dual luciferase reporter assay was used to explore whether let-7b is a sponge miRNA of H19, and AT1R is a novel target of let-7b. A CCK-8 assay and flow cytometry were used to analyse cell proliferation.

RESULTS

The results showed that H19 was highly expressed in the serum and lungs of MCT-induced rats/mice, and H19 was upregulated by PDGF-BB in vitro. H19 upregulated AT1R expression via sponging miRNA let-7b following PDGF-BB stimulation. AT1R is a novel target of let-7b. Moreover, the overexpression of H19 and AT1R could facilitate PASMCs proliferation in vitro. H19 knockout protected mice from pulmonary artery remodeling and PAH following MCT treatment.

CONCLUSION

Our study showed that H19 is highly expressed in MCT-induced rodent lungs and upregulated by PDGF-BB. The H19-let-7b-AT1R axis contributed to the pathogenesis of PAH by stimulating PASMCs proliferation. The H19 knockout had a protective role in the development of PAH. H19 may be a potential tar-get for the treatment of PAH.

LncRNAs in vascular biology and disease

Accumulating studies indicate that long non-coding RNAs (lncRNAs) play important roles in the regulation of diverse biological processes involved in homeostatic control of the vessel wall in health and disease. However, our knowledge of the mechanisms by which lncRNAs control gene expression and cell signaling pathways is still nascent. Furthermore, only a handful of lncRNAs has been functionally evaluated in response to pathophysiological stimuli or in vascular disease states. For example, lncRNAs may regulate endothelial dysfunction by modulating endothelial cell proliferation (e.g. MALAT1, H19) or angiogenesis (e.g. MEG3, MANTIS). LncRNAs have also been implicated in modulating vascular smooth muscle cell (VSMC) phenotypes or vascular remodeling (e.g. ANRIL, SMILR, SENCR, MYOSLID). Finally, emerging studies have implicated lncRNAs in leukocytes activation (e.g. lincRNA-Cox2, linc00305, THRIL), macrophage polarization (e.g. GAS5), and cholesterol metabolism (e.g. LeXis). This review summarizes recent findings on the expression, mechanism, and function of lncRNAs implicated in a range of vascular disease states from mice to human subjects. An improved understanding of lncRNAs in vascular disease may provide new pathophysiological insights and opportunities for the generation of a new class of RNA-based biomarkers and therapeutic targets.