An emerging role for microRNA in the regulation of endothelin-1

Endothelin System in Hypertension and Chronic Kidney Disease

ET (endothelin) is a powerful vasoconstrictor 21-amino acid peptide present in many tissues, which exerts many physiological functions across the body and participates as a mediator in many pathological conditions. ETs exert their effects through ETA and ETB receptors, which can be blocked by selective receptor antagonists. ETs were shown to play important roles among others, in systemic hypertension, particularly when resistant or difficult to control, and in pulmonary hypertension, atherosclerosis, cardiac hypertrophy, subarachnoid hemorrhage, chronic kidney disease, diabetic cardiovascular disease, scleroderma, some cancers, etc. To date, ET antagonists are only approved for the treatment of primary pulmonary hypertension and recently for IgA nephropathy and used in the treatment of digital ulcers in scleroderma. However, they may soon be approved for the treatment of patients with resistant hypertension and different types of nephropathy. Here, the role of ETs is reviewed with a special emphasis on participation in and treatment of hypertension and chronic kidney disease.

The circadian clock protein PER1 is important in maintaining endothelin axis regulation in Dahl salt-sensitive rats

Endothelin-1 (ET-1) is a peptide hormone that acts on its receptors to regulate sodium handling in the kidney's collecting duct. Dysregulation of the endothelin axis is associated with various diseases, including salt-sensitive hypertension and chronic kidney disease. Previously, our lab has shown that the circadian clock gene PER1 regulates ET-1 levels in mice. However, the regulation of ET-1 by PER1 has never been investigated in rats. Therefore, we used a novel model where knockout of Per1 was performed in Dahl salt-sensitive rat background (SS Per1 -/-) to test a hypothesis that PER1 regulates the ET-1 axis in this model. Here, we show increased renal ET-1 peptide levels and altered endothelin axis gene expression in several tissues, including the kidney, adrenal glands, and liver in SS Per1 -/- compared with control SS rats. Edn1 antisense lncRNA Edn1-AS, which has previously been suggested to be regulated by PER1, was also altered in SS Per1 -/- rats compared with control SS rats. These data further support the hypothesis that PER1 is a negative regulator of Edn1 and is important in the regulation of the endothelin axis in a tissue-specific manner.

Altered Expression of Specific MicroRNAs in Plasma of Aneurysmal Subarachnoid Hemorrhage Patients

Background

Aneurysmal subarachnoid hemorrhage (aSAH) is a life-threatening condition with high disability and mortality. MicroRNAs (miRNAs) are reported to play a modulating role in aSAH. We investigated specific plasma microRNAs (miRNAs) associated with aSAH and gained comprehensive insight into its pathological mechanisms.

Methods

This is a prospective case–control study. We used a two-stage approach, with primary screening and ensuing two-step validation stages. Significantly differentially expressed plasma miRNAs between aSAH patients and neurologically healthy controls were initially screened by microarray analysis. These miRNAs were then validated in two groups of independent cohorts using reverse transcription quantitative real-time polymerase chain reaction assays. Functional annotation of these miRNA targets was performed by Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses.

Results

In the primary screening stage, 14 miRNAs were identified as differentially expressed at a significance level of P < 0.05 and fold change >2 between 5 aSAH patients and 5 neurologically healthy controls. In the two validation steps (20 patients vs. 20 control; 40 patients vs. 30 controls), miR-23b-3p, miR-590-5p, miR-20b-5p, miR-142-3p, and miR-29b-3p were found to be significantly down-regulated in patients with aSAH compared with controls. Through these 5 miRNAs, we obtained 32 overlapping target genes, including TGM2, EREG, EDN1, and COL4A1, in three databases that may affect the progression of aSAH. The results of functional annotation revealed mechanisms mainly related to inflammation, smooth muscle cell proliferation and cell adhesion, potentially contributing to the occurrence of aSAH.

Conclusion

We demonstrate that specific miRNAs in plasma, including miR-23b-3p, miR-590-5p, miR-20b-5p, miR-142-3p, and miR-29b-3p, are significantly down-regulated in aSAH patients and may play a modulating role in its progression.

Particulate Matter-Induced Acute Coronary Syndrome: MicroRNAs as Microregulators for Inflammatory Factors

The most prevalent cause of mortality and morbidity worldwide is acute coronary syndrome (ACS) and its consequences. Exposure to particulate matter (PM) from air pollution has been shown to impair both. Various plausible pathogenic mechanisms have been identified, including microRNAs (miRNAs), an epigenetic regulator for gene expression. Endogenous miRNAs, average 22-nucleotide RNAs (ribonucleic acid), regulate gene expression through mRNA cleavage or translation repression and can influence proinflammatory gene expression posttranscriptionally. However, little is known about miRNA responses to fine PM (PM_2.5, PM₁₀, ultrafine particles, black carbon, and polycyclic aromatic hydrocarbon) from air pollution and their potential contribution to cardiovascular consequences, including systemic inflammation regulation. For the past decades, microRNAs (miRNAs) have emerged as novel, prospective diagnostic and prognostic biomarkers in various illnesses, including ACS. We wanted to outline some of the most important studies in the field and address the possible utility of miRNAs in regulating particulate matter-induced ACS (PMIA) on inflammatory factors in this review.

Crosstalk Among NLRP3 Inflammasome, ETBR Signaling, and miRNAs in Stress-Induced Depression-Like Behavior: a Modulatory Role for SGLT2 Inhibitors

Depression is an overwhelming health concern, and many patients fail to optimally respond to available standard therapies. Neuroplasticity and blood-brain barrier (BBB) integrity are the cornerstones of a well-functioning central nervous system, but they are vulnerable to an overly active NLRP3 inflammasome pathway that can also indirectly trigger the release of ET-1 and contribute to the ET system disturbance, which further damages stress resilience mechanisms. Here, the promising yet unexplored antidepressant potential of dapagliflozin (Dapa), a sodium-glucose co-transporter-2 inhibitor, was investigated by assessing its role in the modulation of the NLRP3 inflammasome pathway and ETBR signal transduction, and their impact on neuroplasticity and BBB integrity in an animal model of depression. Dapa (1 mg/kg/day; p.o.) with and without BQ-788 (1 mg/kg/day; i.p.), a specific ETBR blocker, were administered to adolescent male Wistar rats exposed to a 5-week chronic unpredictable stress protocol. The depressive animals demonstrated marked activation of the NLRP3 inflammasome pathway (NF-κB/NLRP3/caspase-1/IL/TNF-α), which was associated with both peripheral and central inflammatory responses. The ET system was disrupted, with noticeable reduction in miR-125a-5p and ETBR gene expression. Cortical ZO-1 expression was downregulated under the influence of NLRP3/TNF-α/miR-501-3p signaling, along with a prominent reduction in hippocampal BDNF and synapsin-1. With ETBR up-regulation being a cornerstone outcome, Dapa administration efficiently created an overall state of resilience, improved histopathological and behavioral variables, and preserved BBB function. These observations were further verified by the results obtained with BQ-788 co-administration. Thus, Dapa may exert its antidepressant action by reinforcing BBB integrity and promoting neuroplasticity through manipulation of the NLRP3/ET-1/ETBR/BDNF/ZO-1 axis, with a significant role for ETBR signaling. Graphical illustration for the proposed mechanisms of the anti-depressant potential of Dapa. Dapa suppressed NLRP3 inflammasome activation and assembly with subsequent inhibition of pro-inflammatory ILs. This results in attenuation of neuro-inflammation, BBB disruption, glial cell activation, TNF-α and ET-1 release, and the enhanced production of neurotrophins. The role of ETBR signaling was emphasized; Dapa possibly augmented ETBR expression, which is thought to boost neurotrophins production. The ETBR blocker, BQ-788, suppressed most of the positive outcomes of Dapa. Finally, miR-125a-5p and miR-501-3p that played major roles in these pathological pathways were modulated by Dapa. It is not yet clear whether Dapa has a direct or rather indirect effect on their expression. BBB, blood-brain barrier; Dapa, dapagliflozin; ET-1, endothelin-1; ETBR, endothelin B receptor; IL, interleukin; NF-κB, nuclear factor kappa B; NLRP3, nucleotide-binding oligomerization domain, leucine-rich repeat and pyrin domain-containing protein 3; TNF-α, tumor necrosis factor-α. Created with BioRender.com.

The effect of selected drugs on the mitigation of myocardial injury caused by gamma radiation

Radiation damage of healthy tissues represents one of the complications of radiotherapy effectiveness. This study is focused on the screening of potentially effective drugs routinely used in medical practice and involved in the mechanism of radiation injury, namely for radiation-induced production of free radicals in the body. Experiments in rats revealed significant reduction of oxidative stress (malondialdehyde) and inflammatory marker (tumor necrosis factor α) in 10 Gy irradiated groups after administration of atorvastatin and a slight decrease after tadalafil administration, which indicates that one of the possible mechanisms for mitigation of radiation-induced cardiac damage could be the modulation of nitric oxide (NO) in endothelium and phosphodiesterase 5. In addition, miRNAs were analyzed as potential markers and therapeutically effective molecules. Expression of miRNA-21 and miRNA-15b showed the most significant changes after irradiation. Atorvastatin and tadalafil normalized changes of miRNA (miRNA-1, miRNA-15b, miRNA-21) expression levels in irradiated hearts. This screening study concludes that administration of specific drugs could mitigate the negative impact of radiation on the heart, but more detailed experiments oriented to other aspects of drug effectiveness and their exact mechanisms are still needed.

Interplay of the Circadian Clock and Endothelin System

The peptide hormone endothelin-1 and its receptors are linked to several disease states. Pharmacological inhibition of this pathway has proven beneficial in pulmonary hypertension, yet its potential in other disease states remains to be realized. This review considers an often understudied aspect of endothelin biology, circadian rhythm regulation and how understanding the intersection between endothelin signaling and the circadian clock may be leveraged to realize the potential of endothelin-based therapeutics.

Knockout of the circadian clock protein PER1 results in sex-dependent alterations of ET-1 production in mice in response to a high-salt diet plus mineralocorticoid treatment

Previously, we showed that global knockout (KO) of the circadian clock transcription factor PER1 in male, but not female, mice fed a high-salt diet plus mineralocorticoid treatment (HS/DOCP) resulted in nondipping hypertension and decreased night/day ratio of sodium (Na) excretion. Additionally, we have shown that the endothelin-1 (ET-1) gene is targeted by both PER1 and aldosterone. We hypothesized that ET-1 would exhibit a sex-specific response to HS/DOCP treatment in PER1 KO. Here we show that male, but not female, global PER1 KO mice exhibit a decreased night/day ratio of urinary ET-1. Gene expression analysis revealed significant genotype differences in ET-1 and endothelin A receptor (ET_A) expression in male, but not female, mice in response to HS/DOCP. Additionally, both wild-type and global PER1 KO male mice significantly increase endothelin B receptor (ET_B) expression in response to HS/DOCP, but female mice do not. Finally, siRNA-mediated knockdown of PER1 in mouse cortical collecting duct cells (mpkCCDc14) resulted in increased ET-1 mRNA expression and peptide secretion in response to aldosterone treatment. These data suggest that PER1 is a negative regulator of ET-1 expression in response to HS/DOCP, revealing a novel mechanism for the regulation of renal Na handling in response to HS/DOCP treatment.

Emerging roles of let‑7d in attenuating pulmonary arterial hypertension via suppression of pulmonary artery endothelial cell autophagy and endothelin synthesis through ATG16L1 downregulation

Pulmonary arterial hypertension (PAH) is a severe disease characterized by elevated pulmonary arterial pressure and pulmonary vascular resistance, resulting in right ventricular failure and death. Compelling evidence has suggested the roles of microRNAs (miRNAs/miRs) in PAH. The present study investigated the possible effects of miR-let-7d on PAH through autophagy-related 16-like 1 (ATG16L1). Initially, the serum levels of let-7d in PAH patients were detected. Rats were then treated with monocrotaline to induce a rat model of PAH, after which the right ventricular systolic pressure (RVSP) and right ventricular hypertrophy index (RVHI) were determined. Next, the putative binding sites between let-7d and ATG16L1 were detected. The expression of let-7d and ATG16L1 in PAH rat models and cells was upregulated or downregulated to assess the effects of these molecules on autophagy in pulmonary artery vascular endothelial cells (PAECs) and on endothelin synthesis. In addition, the levels of p62, LC3-I, LC3-II, LC3B and endothelin-1 (ET-1) were assessed. The results obtained revealed that let-7d was downregulated in the serum of PAH patients and rats with PAH. Importantly, ATG16L1 was found to be a target gene of let-7d and let-7d could suppress the expression of ATG16L1. Overexpression of let-7d was found to reduce RVSP and RVHI values. Additionally, upregulation of let-7d or depletion of ATG16L1 led to suppression of PAEC autophagy and endothelin synthesis, corresponding to decreased ratios of LC3-II to LC3-I and reduced levels of LC3B but elevated levels of p62 in PAECs and ET-1 in plasma and lung tissues. In summary, let-7d upregulation alleviates PAH by inhibiting autophagy in PAECs and suppressing endothelin synthesis through negative regulation of ATG16L1.

EDN1-AS, A Novel Long Non-coding RNA Regulating Endothelin-1 in Human Proximal Tubule Cells

Endothelin-1 (ET-1) is a peptide hormone that functions as a vasoconstrictor in the vasculature, whereas in the collecting duct of the kidney it exerts blood pressure-lowering effects via natriuretic actions. Aberrant ET-1 signaling is associated with several pathological states including hypertension and chronic kidney disease. ET-1 expression is regulated largely through transcriptional control of the gene that encodes ET-1, EDN1. Here we report a long, non-coding RNA (lncRNA) that appears to be antisense to the EDN1 gene, called EDN1-AS. Because EDN1-AS represents a potential novel mechanism to regulate ET-1 expression, we examined the regulation of EDN1-AS expression and action. A putative glucocorticoid receptor response (GR) element upstream of the predicted EDN1-AS transcription start site was identified using the ENCODE database and the UCSC genome browser. Two homozygous deletion clones of the element were generated using CRISPR/Cas9. This deletion resulted in a significant increase in the expression of EDN1-AS, which was associated with increased secretion of ET-1 peptide from HK-2 cells (two-fold increase in KO cells vs. CNTL, n = 7, P < 0.05). Phenotypic characterization of these CRISPR clones revealed a difference in cell growth rates. Using a standard growth assay, we determined that the KO1 clone exhibited a three-fold increase in growth over 8 days compared to control cells (n = 4, P < 0.01) and the KO2 clone exhibited a two-fold increase (n = 4, P < 0.01). These results support a role for EDN1-AS as a novel regulatory mechanism of ET-1 expression and cellular proliferation.

The role of epigenetic changes in preeclampsia

Preeclampsia (PE) is a disorder affecting 2-10% of pregnancies and has a major role for perinatal and maternal mortality and morbidity. PE can be occurred by initiation of new hypertension combined with proteinuria after 20 weeks gestation, as well as various reasons such as inflammatory cytokines, poor trophoblast invasion can be related with PE disease. Environmental factors can cause epigenetic changes including DNA methylation, microRNAs (miRNAs), and histone modification that may be related to different diseases such as PE. Abnormal DNA methylation during placentation is the most important epigenetic factor correlated with PE. Moreover, changes in histone modification like acetylation and also the effect of overregulation or low regulation of miRNAs or long noncoding RNAs on variety signaling pathways can be resulted in PE. The aim of this review is to describe of studies about epigenetic changes in PE and its therapeutic strategies.

Preeclamptic plasma stimulates the expression of miRNAs, leading to a decrease in endothelin-1 production in endothelial cells

Preeclampsia is a major cause of maternal and fetal morbidity and mortality worldwide. It is a multisystem pregnancy syndrome characterized by general endothelial dysfunction caused mainly by plasma factors and debris in endothelial cells. It is widely accepted that endothelin-1 (ET-1) is involved in the pathophysiology of preeclampsia, and so it is of interest to ascertain whether the ET-1 gene (EDN1) can be targeted with tools such as miRNAs. Therefore, we investigated the relationship between the expression of miRNAs that putatively target EDN1 (and so affect ET-1 levels) in HUVECs incubated with plasma from preeclamptic women. EDN1 expression and ET-1 levels in HUVECs incubated with plasma from women with preeclampsia were similar to those in plasma from healthy pregnant women. Expression of miRNAs let-7a, -7b, and -7c, and to a lesser degree 125a and 125b, was increased in preeclampsia. Expression of miRNAs of the let-7 family was significantly negatively correlated with ET-1 levels in preeclampsia. Transfection of the preeclampsia cultures with mimic miRNA let-7 decreased ET-1 levels. Our findings show that preeclamptic plasma stimulates the expression of miRNAs in HUVECs, leading to a decrease in ET-1levels, which suggests that therapeutic miRNAs may aid in the management of preeclampsia.

Diabetic retinopathy and endothelin system: microangiopathy versus endothelial dysfunction

In the face of the global epidemic of diabetes, it is critical that we update our knowledge about the pathogenesis of diabetes and the related micro alterations on the vascular network in the body. This may ultimately lead to early diagnosis and novel treatment options for delaying the progression of diabetic complications. Research has recently revealed the pivotal role of endothelin in the pathogenesis of diabetic complications, particularly in the regulation of the capillary flow, which is affected in the course of retinopathy. Although there are several reviews on various approaches to the treatment of diabetes, including normalization of glucose and fat metabolism, no reviews in literature have focused on the endothelin system as a therapeutic target or early indicator of diabetic microangiopathy. In this review, we summarize some of the experimental and clinical evidence suggesting that current therapeutic approaches to diabetes may include the modulation of the blood concentration of compounds of the endothelin system. In addition, we will briefly discuss the beneficial effects produced by the inhibition of the production of high levels of endothelin in vasculopathy, with focus on diabetic retinopathy. The cutting-edge technology currently widely used in opththalmology, such as the OCT angiography, allows us to detect very early retinal morphological changes alongside alterations in choroidal and retinal vascular network. Combination of such changes with highly sensitive measurements of alterations in serum concentrations of endothelin may lead to more efficient early detection and treatment of diabetes and related macro/microvascular complications.

β-arrestin1 at the cross-road of endothelin-1 signaling in cancer

The advent of targeted therapeutics in human cancer has begun to find novel druggable targets and, in this context, the endothelin-1 receptor (ET-1R), namely ET_A receptor (ET_AR) and ET_B receptor, among the GPCR family represents a class of highly druggable molecules in cancer. ET-1R are aberrantly expressed in human malignancies, potentially representing prognostic factors. Their activation by ligand stimulation initiate signaling cascades activating different downstream effectors, allowing precise control over multiple signaling pathways. ET-1R regulates cell proliferation, survival, motility, cytoskeletal changes, angiogenesis, metastasis as well as drug resistance. The molecular events underlying these responses are the activation of transcriptional factors and coactivators, and downstream genes, acting as key players in tumor growth and progression. ET-1R represent crucial cancer targets that have been exploited for ET-1R therapeutics. Importantly, efforts to explore new information of ET_AR in cancer have uncovered that their functions are crucially regulated by multifunctional scaffold protein β-arrestins (β-arrs) which orchestrate the multidimensionality of ET_AR signaling into highly regulated and distinct signaling complexes, a property that is highly advantageous for tumor signaling. Moreover, the role of β-arr1 in ET-1 signaling in cancer highlights why the pleiotropic effects of ET-1 and its dynamic signaling are more complex than previously recognized. In order to improve therapeutic strategies that interfere with the widespread effects of ET-1R, it is important to consider antagonists able to turn the receptors “off” selectively controlling β-arr1-dependent signaling, highlighting the possibility that targeting ET_AR/β-arr1 may display a large therapeutic window in cancer.

Peroxisome Proliferator-Activated Receptor γ and microRNA 98 in Hypoxia-Induced Endothelin-1 Signaling

Endothelin-1 (ET-1) plays a critical role in endothelial dysfunction and contributes to the pathogenesis of pulmonary hypertension (PH). We hypothesized that peroxisome proliferator-activated receptor γ (PPARγ) stimulates microRNAs that inhibit ET-1 and pulmonary artery endothelial cell (PAEC) proliferation. The objective of this study was to clarify molecular mechanisms by which PPARγ regulates ET-1 expression in vitro and in vivo. In PAECs isolated from patients with pulmonary arterial hypertension, microRNA (miR)-98 expression was reduced, and ET-1 protein levels and proliferation were increased. Similarly, hypoxia reduced miR-98 and increased ET-1 levels and PAEC proliferation in vitro. In vivo, hypoxia reduced miR-98 expression and increased ET-1 and proliferating cell nuclear antigen (PCNA) levels in mouse lung, derangements that were aggravated by treatment with the vascular endothelial growth factor receptor antagonist Sugen5416. Reporter assays confirmed that miR-98 binds directly to the ET-1 3'-untranslated region. Compared with littermate control mice, miR-98 levels were reduced and ET-1 and PCNA expression were increased in lungs from endothelial-targeted PPARγ knockout mice, whereas miR-98 levels were increased and ET-1 and PCNA expression was reduced in lungs from endothelial-targeted PPARγ-overexpression mice. Gain or loss of PPARγ function in PAECs in vitro confirmed that alterations in PPARγ were sufficient to regulate miR-98, ET-1, and PCNA expression. Finally, PPARγ activation with rosiglitazone regimens that attenuated hypoxia-induced PH in vivo and human PAEC proliferation in vitro restored miR-98 levels. The results of this study show that PPARγ regulates miR-98 to modulate ET-1 expression and PAEC proliferation. These results further clarify molecular mechanisms by which PPARγ participates in PH pathogenesis and therapy.

[MiRNAs in the diagnosis of cardiovascular diseases associated with type 2 diabetes mellitus and obesity]

Worldwide, the number of patients with type 2 diabetes mellitus (T2DM), obesity, and cardiovascular diseases (CVD) continues to increase steadily. Despite long-term studies of obesity and concomitant diseases, the molecular genetic bases for the development of these pathological conditions have remained the subject of numerous investigations so far. Recent investigations point to the involvement of miRNAs as dynamic modifiers of the pathogenesis of various pathological conditions, including obesity, T2DM, and CVD. MicroRNAs are involved in various biological processes underlying the development of CVDs, including endothelial dysfunction, cell adhesion, and atherosclerotic plaque formation and rupture. Some of them are considered as potential sensitive diagnostic markers of coronary heart disease and acute myocardial infarction. Approximately 1,000 microRNAs are found in the human body. It has been determined that miRNAs regulate 30% of all human genes. Among them there are about 50 circulating miRNAs presumably associated with cardiovascular diseases. This review provides recent data on the participation of some miRNAs in various pathological and physiological states associated with CVD in DM and obesity. An extended and exact understanding of the function of miRNAs in the gene regulatory networks associated with cardiovascular risk in obesity will be able to reveal new mechanisms for the progression of disease, to predict its development, and to elaborate innovative therapeutic strategies.

MicroRNAs and cardiovascular diseases

Coronary artery diseases (CAD) and heart failure have high mortality rate in the world, although much progress has been made in this field in last two decades. There is still a clinical need for a novel diagnostic approach and a therapeutic strategy to decrease the incidence of CAD. MicroRNAs (miRNAs) are highly conserved noncoding small RNA molecules that regulate a large fraction of the genome by binding to complementary messenger RNA sequences, resulting in posttranscriptional gene silencing. Recent studies have shown that specific miRNAs are involved in whole stage of atherosclerosis, from endothelium dysfunction to plaque rupture. These findings suggest that miRNAs are potential biomarkers in early diagnosis and therapeutic targets in CAD. In the present review, we highlight the role of miRNAs in every stage of atherosclerosis, and discuss the prospects of miRNAs in the near future.

Emerging role of microRNAs in modulating endothelin-1 expression in gastric cancer

Endothelin-1 (ET-1) is a small 21-amino acid peptide that is known to exert diverse biological effects on a wide variety of tissues and cell types through its own receptors. The ET-1-ETRA axis is frequently dysfunctional in numerous types of carcinomas, and contributes to the promotion of cell growth and migration. microRNAs (miRNAs) are small non-coding RNAs that play a critical role in carcinogenesis through mRNA degradation or the translational inhibition of cancer-associated protein-coding genes. However, the role of ET-1 and the relationship between ET-1 and miRNAs in gastric cancer remain unknown. Results of the analysis of the database of The Cancer Genome Atlas (TCGA) revealed that ET-1 is significantly overexpressed in gastric cancer cells when compared with its expression in adjacent normal cells. Exogenous ET-1 significantly enhanced gastric cancer cell proliferation, implying that ET-1 plays an oncogenic role in gastric cancer carcinogenesis. Using a luciferase reporter assay we showed that 18 miRNA candidates had a significant silencing effect on ET-1 expression by up to 20% in HEK293T cells. Among them, 5 miRNAs (miR-1, miR-101, miR-125A, miR-144 and let-7c) were shown to be involved in ET-1 silencing through post-transcriptional modulation in gastric cancer. Our data also revealed that DNA hypermethylation contributes to the silenced miR-1 expression in gastric cancer cells. The ectopic expression of miR-1 significantly inhibited AGS cell proliferation by suppressing ET-1 expression. Overall, our study revealed that ET-1 overexpression may be due to DNA hypermethylation resulting in the silencing of miR-1 expression in gastric cancer cells. In addition, we identified several miRNAs as potential modulators for ET-1 in gastric cancer, which may be used as targets for gastric cancer therapy.

Melatonin reduces endothelin-1 expression and secretion in colon cancer cells through the inactivation of FoxO-1 and NF-κβ

Melatonin is an indoleamine that is synthesised from tryptophan under the control of the enzymes arylalkylamine N-acetyltransferase (AA-NAT) and acetylserotonin methyltransferase (ASMT). Melatonin inhibits colon cancer growth in both in vivo and in vitro models; however, a precise mechanism responsible for inhibiting tumour growth has not been clearly described. Endothelin-1 (ET-1) is a peptide that acts as a survival factor in colon cancer, inducing cell proliferation, protecting carcinoma cells from apoptosis and promoting angiogenesis. The data presented show that melatonin inhibits edn-1 mRNA expression (the first step in ET-1 synthesis), ECE-1 protein expression and the release of ET-1 from colorectal cancer cells in vitro. ET-1 levels in cultured media present a similar inhibition pattern to that of edn-1 mRNA expression despite the inhibition of ECE-1 protein after melatonin treatment, which suggests that an endopeptidase other than ECE-1 could be mainly responsible for ET-1 synthesis. The inhibition of edn-1 expression is due to an inactivation of FoxO1 and NF-κβ transcription factors. FoxO1 inactivation is associated with an increased Src phosphorylation, due to elevated cAMP content and PKA activity, whereas NF-κβ inactivation is associated with the blockade of Akt and ERK phosphorylation due to the inhibition of PKC activity after melatonin treatment. Melatonin also inhibits edn-1 promoter activity regulated by FoxO1 and NF-κβ. Finally, a significant correlation was observed between AA-NAT and edn-1 expression downregulation in human colorectal cancer tissues. In conclusion, melatonin may be useful in treating colon carcinoma in which the activation of ET-1 plays a role in tumour growth and progression.

Tissue-specific and time-dependent regulation of the endothelin axis by the circadian clock protein Per1

AIMS

The present study is designed to consider a role for the circadian clock protein Per1 in the regulation of the endothelin axis in mouse kidney, lung, liver and heart. Renal endothelin-1 (ET-1) is a regulator of the epithelial sodium channel (ENaC) and blood pressure (BP), via activation of both endothelin receptors, ETA and ETB. However, ET-1 mediates many complex events in other tissues.

MAIN METHODS

Tissues were collected in the middle of murine rest and active phases, at noon and midnight, respectively. ET-1, ETA and ETB mRNA expressions were measured in the lung, heart, liver, renal inner medulla and renal cortex of wild type and Per1 heterozygous mice using real-time quantitative RT-PCR.

KEY FINDINGS

The effect of reduced Per1 expression on levels of mRNAs and the time-dependent regulation of expression of the endothelin axis genes appeared to be tissue-specific. In the renal inner medulla and the liver, ETA and ETB exhibited peaks of expression in opposite circadian phases. In contrast, expressions of ET-1, ETA and ETB in the lung did not appear to vary with time, but ET-1 expression was dramatically decreased in this tissue in Per1 heterozygous mice. Interestingly, ET-1 and ETA, but not ETB, were expressed in a time-dependent manner in the heart.

SIGNIFICANCE

Per1 appears to regulate expression of the endothelin axis genes in a tissue-specific and time-dependent manner. These observations have important implications for our understanding of the best time of day to deliver endothelin receptor antagonists.

MicroRNA regulation of endothelin-1 mRNA in renal collecting duct cells

AIMS

Recently, microRNAs (miRNAs) have been implicated in control of Edn1 mRNA in several tissues. Here we examined the role of miRNA action on Edn1 mRNA expression in renal distal collecting duct cells.

MAIN METHODS

A microarray study was conducted to provide a comprehensive assessment of miRNAs present in a murine inner medullary collecting duct (mIMCD-3) cell line. The experiment was designed as a comparison between mIMCD-3 cells grown in the presence and absence of aldosterone. Argonaute (Ago) immunoprecipitation experiments were used to investigate binding of the RNA induced silencing complex (RISC) to Edn1 mRNA.

KEY FINDINGS

Thirty-four miRNAs were detected in very high abundance in mIMCD-3 cells, and a large number of others were present at lower levels. The microarray experiments were validated by quantitative PCR analysis of selected miRNAs. The microarray data, in combination with in silico examination of the Edn1 3' UTR provided a panel of candidate miRNAs that could act upon the Edn1 expression. Edn1 mRNA was co-immunoprecipitated with an Argonaute protein antibody, and this interaction was blocked by anti-miR-709 oligonucleotides.

SIGNIFICANCE

These results define the miRNA landscape of the mIMCD-3 cell line. Moreover, Edn1 was shown to interact with Argonaute protein suggesting that it is a target of the RNA induced silencing complex (RISC).

Flavonol-rich dark cocoa significantly decreases plasma endothelin-1 and improves cognition in urban children

Air pollution exposures are linked to systemic inflammation, cardiovascular and respiratory morbidity and mortality, neuroinflammation and neuropathology in young urbanites. In particular, most Mexico City Metropolitan Area (MCMA) children exhibit subtle cognitive deficits, and neuropathology studies show 40% of them exhibiting frontal tau hyperphosphorylation and 51% amyloid-β diffuse plaques (compared to 0% in low pollution control children). We assessed whether a short cocoa intervention can be effective in decreasing plasma endothelin 1 (ET-1) and/or inflammatory mediators in MCMA children. Thirty gram of dark cocoa with 680 mg of total flavonols were given daily for 10.11 ± 3.4 days (range 9–24 days) to 18 children (10.55 years, SD = 1.45; 11F/7M). Key metabolite ratios in frontal white matter and in hippocampus pre and during cocoa intervention were quantified by magnetic resonance spectroscopy. ET-1 significantly decreased after cocoa treatment (p = 0.0002). Fifteen children (83%) showed a marginally significant individual improvement in one or both of the applied simple short memory tasks. Endothelial dysfunction is a key feature of exposure to particulate matter (PM) and decreased endothelin-1 bioavailability is likely useful for brain function in the context of air pollution. Our findings suggest that cocoa interventions may be critical for early implementation of neuroprotection of highly exposed urban children. Multi-domain nutraceutical interventions could limit the risk for endothelial dysfunction, cerebral hypoperfusion, neuroinflammation, cognitive deficits, structural volumetric detrimental brain effects, and the early development of the neuropathological hallmarks of Alzheimer's and Parkinson's diseases.