Endothelin Signaling Research Articles

Assessing candidate DLX-regulated genes in the first pharyngeal arch of chick embryos.

Insights into the development and evolution of asymmetrical jaws will require an understanding of the gene regulatory networks that underpin the differential morphogenesis of the maxillary and mandibular domains of the first pharyngeal arch in a variety of gnathostomes. While a robust relationship has been demonstrated between jaw patterning and the Endothelin-Dlx gene axis, much less is known of the next level of genes in the jaw patterning hierarchy. Several genes, whose expression depends on Dlx5 and/or Dlx6, have been identified in mice. Here, we examined the expression patterns of the chick orthologues of some of those genes, namely GSC, PITX1, HAND2, and GBX2, and tested their dependence on endothelin signaling to assess whether there is a conserved regulatory relationship between those genes in the chick embryo. To further validate these genes as direct DLX targets, we identified conserved non-coding sequences containing candidate DLX binding motifs and demonstrated DLX-responsiveness in vitro. The evidence presented in this study combines to support the hypothesis that these four genes are direct targets of DLX transcription factors in the lower jaw-forming tissue.

Lineage-specific intersection of endothelin and GDNF signaling in enteric nervous system development.

Two major ligand-receptor signaling axes - endothelin Edn3 and its receptor Ednrb, and glial-derived neurotrophic factor (GDNF) and its receptor Ret - are required for migration of enteric nervous system (ENS) progenitors to the hindgut. Mutations in either component cause colonic aganglionosis, also called Hirschsprung disease. Here, we have used Wnt1Cre and Pax2Cre in mice to show that these driver lines label distinct ENS lineages during progenitor migration and in their terminal hindgut fates. Both Cre lines result in Hirschsprung disease when combined with conditional Ednrb or conditional Ret alleles. In vitro explant assays and analysis of lineage-labeled mutant embryos show that GDNF but not Edn3 is a migration cue for cells of both lineages. Instead, Edn3-Ednrb function is required in both for GDNF responsiveness albeit in different ways: by expanding the Ret+ population in the Pax2Cre lineage, and by supporting Ret function in Wnt1Cre-derived cells. Our results demonstrate that two distinct lineages of progenitors give rise to the ENS, and that these divergently utilize endothelin signaling to support migration to the hindgut.

Lineage-specific intersection of endothelin and GDNF signaling in enteric nervous system development

Lineage-specific intersection of endothelin and GDNF signaling in enteric nervous system development

Placode and neural crest origins of congenital deafness in mouse models of Waardenburg-Shah syndrome.

Mutations in the human genes encoding the endothelin ligand-receptor pair EDN3 and EDNRB cause Waardenburg-Shah syndrome (WS4), which includes congenital hearing impairment. The current explanation for auditory dysfunction is defective migration of neural crest-derived melanocytes to the inner ear. We explored the role of endothelin signaling in auditory development in mice using neural crest-specific and placode-specific Ednrb mutation plus related genetic resources. On an outbred strain background, we find a normal representation of melanocytes in hearing-impaired mutant mice. Instead, our results in neural crest-specific Ednrb mutants implicate a previously unrecognized role for glial support of synapse assembly between auditory neurons and cochlear hair cells. Placode-specific Ednrb mutation also caused impaired hearing, resulting from deficient synaptic transmission. Our observations demonstrate the significant influence of genetic modifiers in auditory development, and invoke independent and separable roles for endothelin signaling in the neural crest and placode lineages to create a functional auditory circuitry.

Endothelin receptor B is required for the blood pressure-lowering effect of G protein-coupled estrogen receptor 1 in ovariectomized rats.

Activation of G protein-coupled estrogen receptor 1 (GPER1) elicits antihypertensive actions in different animal models. The endothelin-1 signaling system plays a fundamental role in blood pressure regulation. Lack of functional endothelin receptor B (ETB) evokes hypertension and salt sensitivity. GPER1 and ETB interact to promote urinary sodium excretion in female rats. We hypothesized that activation of GPER1 protects against hypertension and salt sensitivity induced by ETB antagonism in female rats. Female Sprague-Dawley rats were implanted with radiotelemetry. Animals were then subjected to ovariectomy and simultaneously implanted with minipumps to deliver either the GPER1 agonist G1 or its corresponding vehicle. Two weeks post surgery, we initiated treatment of rats with the ETB antagonist A-192621. Animals were maintained on a normal-salt diet and then challenged with a high-salt diet for an additional 5 days. Assessment of mean arterial blood pressure revealed an increase in vehicle-treated, but not G1-treated, rats in response to ovariectomy. A-192621 increased blood pressure in normal-salt diet-fed vehicle- and G1-treated rats. G1 improved the circadian blood pressure rhythms that were disrupted in A-192621-treated ovariectomized rats. Thus, although systemic GPER1 activation did not protect ovariectomized rats from hypertension and salt sensitivity induced by ETB antagonism, it maintained circadian blood pressure rhythms. Functional ETB is required to elicit the antihypertensive actions of GPER1. Additional studies are needed to improve our understanding of the interaction between G protein-coupled receptors in regulating circadian blood pressure rhythm.NEW & NOTEWORTHY Systemic G protein-coupled estrogen receptor 1 (GPER1) activation in rats prevents the increase in blood pressure evoked by ovariectomy. Blockade of endothelin receptor B negates the blood pressure-lowering impact of GPER1 in ovariectomized rats. Endothelin receptor B plays an important role in mediating the blood pressure-lowering action of GPER1 activation in female rats.

Targeting endothelin signaling in podocyte injury and diabetic nephropathy-diabetic kidney disease

Targeting endothelin signaling in podocyte injury and diabetic nephropathy-diabetic kidney disease

Blockade of endothelin receptors mitigates SARS-CoV-2-induced osteoarthritis.

Joint pain and osteoarthritis can occur as coronavirus disease 2019 (COVID-19) sequelae after infection. However, little is known about the damage to articular cartilage. Here we illustrate knee joint damage after wild-type, Delta and Omicron variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in vivo. Rapid joint injury with cystic lesions at the osteochondral junction was observed in two patients with post-COVID osteoarthritis and recapitulated in a golden Syrian hamster model. SARS-CoV-2-activated endothelin-1 signalling increased vascular permeability and caused viral spike proteins leakage into the subchondral bone. Osteoclast activation, chondrocyte dropout and cyst formation were confirmed histologically. The US Food and Drug Administration-approved endothelin receptor antagonist, macitentan, mitigated cystic lesions and preserved chondrocyte number in the acute phase of viral infection in hamsters. Delayed macitentan treatment at post-acute infection phase alleviated chondrocyte senescence and restored subchondral bone loss. It is worth noting that it could also attenuate viral spike-induced joint pain. Our work suggests endothelin receptor blockade as a novel therapeutic strategy for post-COVID arthritis.

Navigating the Landscape of Coronary Microvascular Research: Trends, Triumphs, and Challenges Ahead.

Coronary microvascular dysfunction (CMD) refers to structural and functional abnormalities of the microcirculation that impair myocardial perfusion. CMD plays a pivotal role in numerous cardiovascular diseases, including myocardial ischemia with non-obstructive coronary arteries, heart failure, and acute coronary syndromes. This review summarizes recent advances in CMD pathophysiology, assessment, and treatment strategies, as well as ongoing challenges and future research directions. Signaling pathways implicated in CMD pathogenesis include adenosine monophosphate-activated protein kinase/Krüppel-like factor 2/endothelial nitric oxide synthase (AMPK/KLF2/eNOS), nuclear factor erythroid 2-related factor 2/antioxidant response element (Nrf2/ARE), Angiotensin II (Ang II), endothelin-1 (ET-1), RhoA/Rho kinase, and insulin signaling. Dysregulation of these pathways leads to endothelial dysfunction, the hallmark of CMD. Treatment strategies aim to reduce myocardial oxygen demand, improve microcirculatory function, and restore endothelial homeostasis through mechanisms including vasodilation, anti-inflammation, and antioxidant effects. Traditional Chinese medicine (TCM) compounds exhibit therapeutic potential through multi-targeted actions. Small molecules and regenerative approaches offer precision therapies. However, challenges remain in translating findings to clinical practice and developing effective pharmacotherapies. Integration of engineering with medicine through microfabrication, tissue engineering and AI presents opportunities to advance the diagnosis, prediction, and treatment of CMD.

Phillyrin improves myocardial remodeling in salt-sensitive hypertensive mice by reducing endothelin1 signaling.

Prolonged exposure to chronic hypertension places the heart under excessive strain, resulting in myocardial remodeling. Phillyrin, derived from the natural plant Forsythia suspensa, has been found to possess cardioprotective properties. The objective of this study is to investigate the role and mechanism of phillyrin in hypertension-induced myocardial remodeling in mice. We constructed a mouse model of salt-sensitive hypertension. The mice were treated with varying doses of phillyrin, and their blood pressure, cardiac function, cardiac hypertrophy, fibrosis, inflammation, and other conditions were assessed. Our research findings demonstrated that phillyrin has the potential to lower blood pressure, enhance cardiac function, and mitigate cardiac hypertrophy, fibrosis, and inflammatory responses in deoxycorticosterone acetate-salt hypertension mice. In hypertensive mice, there was an elevated expression of endothelin1 (ET-1) in heart tissue, which can be reduced by phillyrin. Additionally, phillyrin effectively reduced the hypertrophy of H9c2 cells induced by ET-1 stimulation. Our research highlights the therapeutic capabilities of phillyrin in the treatment of myocardial remodeling through the reduction of ET-1 signaling. These results contribute to the advancement of novel applications for phillyrin and establish a solid conceptual basis for future investigations in this area.

The β-arrestin1/endothelin axis bolsters ovarian fibroblast-dependent invadosome activity and cancer cell metastatic potential

Recruitment of fibroblasts to tumors and their activation into cancer-associated fibroblasts (CAFs) is a strategy used by tumor cells to direct extracellular matrix (ECM) remodeling, invasion, and metastasis, highlighting the need to investigate the molecular mechanisms driving CAF function. Endothelin-1 (ET-1) regulates the communication between cancer and stroma and facilitates the progression of serous ovarian cancer (SOC). By binding to Endothelin A (ETA) and B (ETB) receptors, ET-1 enables the recruitment of β-arrestin1 (β-arr1) and the formation of signaling complexes that coordinate tumor progression. However, how ET-1 receptors might “educate” human ovarian fibroblasts (HOFs) to produce altered ECM and promote metastasis remains to be elucidated. This study identifies ET-1 as a pivotal factor in the activation of CAFs capable of proteolytic ECM remodeling and the generation of heterotypic spheroids containing cancer cells with a propensity to metastasize. An autocrine/paracrine ET-1/ETA/BR/β-arr1 loop enhances HOF proliferation, upregulates CAF marker expression, secretes pro-inflammatory cytokines, and increases collagen contractility, and cell motility. Furthermore, ET-1 facilitates ECM remodeling by promoting the lytic activity of invadosome and activation of integrin β1. In addition, ET-1 signaling supports the formation of heterotypic HOF/SOC spheroids with enhanced ability to migrate through the mesothelial monolayer, and invade, representing metastatic units. The blockade of ETA/BR or β-arr1 silencing prevents CAF activation, invadosome function, mesothelial clearance, and the invasive ability of heterotypic spheroids. In vivo, therapeutic inhibition of ETA/BR using bosentan (BOS) significantly reduces the metastatic potential of combined HOFs/SOC cells, associated with enhanced apoptotic effects on tumor cells and stromal components. These findings support a model in which ET-1/β-arr1 reinforces tumor/stroma interaction through CAF activation and fosters the survival and metastatic properties of SOC cells, which could be counteracted by ETA/BR antagonists.

Catecholamine treatment induces reversible heart injury and cardiomyocyte gene expression

BackgroundCatecholamines are commonly used as therapeutic drugs in intensive care medicine to maintain sufficient organ perfusion during shock. However, excessive or sustained adrenergic activation drives detrimental cardiac remodeling and may lead to heart failure. Whether catecholamine treatment in absence of heart failure causes persistent cardiac injury, is uncertain. In this experimental study, we assessed the course of cardiac remodeling and recovery during and after prolonged catecholamine treatment and investigated the molecular mechanisms involved.ResultsC57BL/6N wild-type mice were assigned to 14 days catecholamine treatment with isoprenaline and phenylephrine (IsoPE), treatment with IsoPE and subsequent recovery, or healthy control groups. IsoPE improved left ventricular contractility but caused substantial cardiac fibrosis and hypertrophy. However, after discontinuation of catecholamine treatment, these alterations were largely reversible. To uncover the molecular mechanisms involved, we performed RNA sequencing from isolated cardiomyocyte nuclei. IsoPE treatment resulted in a transient upregulation of genes related to extracellular matrix formation and transforming growth factor signaling. While components of adrenergic receptor signaling were downregulated during catecholamine treatment, we observed an upregulation of endothelin-1 and its receptors in cardiomyocytes, indicating crosstalk between both signaling pathways. To follow this finding, we treated mice with endothelin-1. Compared to IsoPE, treatment with endothelin-1 induced minor but longer lasting changes in cardiomyocyte gene expression. DNA methylation-guided analysis of enhancer regions identified immediate early transcription factors such as AP-1 family members Jun and Fos as key drivers of pathological gene expression following catecholamine treatment.ConclusionsThe results from this study show that prolonged catecholamine exposure induces adverse cardiac remodeling and gene expression before the onset of left ventricular dysfunction which has implications for clinical practice. The observed changes depend on the type of stimulus and are largely reversible after discontinuation of catecholamine treatment. Crosstalk with endothelin signaling and the downstream transcription factors identified in this study provide new opportunities for more targeted therapeutic approaches that may help to separate desired from undesired effects of catecholamine treatment.

Coronary Artery Disease Risk Variant Dampens the Expression of CALCRL by Reducing HSF Binding to Shear Stress Responsive Enhancer in Endothelial Cells In Vitro.

CALCRL (calcitonin receptor-like) protein is an important mediator of the endothelial fluid shear stress response, which is associated with the genetic risk of coronary artery disease. In this study, we functionally characterized the noncoding regulatory elements carrying coronary artery disease that risks single-nucleotide polymorphisms and studied their role in the regulation of CALCRL expression in endothelial cells. To functionally characterize the coronary artery disease single-nucleotide polymorphisms harbored around the gene CALCRL, we applied an integrative approach encompassing statistical, transcriptional (RNA-seq), and epigenetic (ATAC-seq [transposase-accessible chromatin with sequencing], chromatin immunoprecipitation assay-quantitative polymerase chain reaction, and electromobility shift assay) analyses, alongside luciferase reporter assays, and targeted gene and enhancer perturbations (siRNA and clustered regularly interspaced short palindromic repeats/clustered regularly interspaced short palindromic repeat-associated 9) in human aortic endothelial cells. We demonstrate that the regulatory element harboring rs880890 exhibits high enhancer activity and shows significant allelic bias. The A allele was favored over the G allele, particularly under shear stress conditions, mediated through alterations in the HSF1 (heat shock factor 1) motif and binding. CRISPR deletion of rs880890 enhancer resulted in downregulation of CALCRL expression, whereas HSF1 knockdown resulted in a significant decrease in rs880890-enhancer activity and CALCRL expression. A significant decrease in HSF1 binding to the enhancer region in endothelial cells was observed under disturbed flow compared with unidirectional flow. CALCRL knockdown and variant perturbation experiments indicated the role of CALCRL in mediating eNOS (endothelial nitric oxide synthase), APLN (apelin), angiopoietin, prostaglandins, and EDN1 (endothelin-1) signaling pathways leading to a decrease in cell proliferation, tube formation, and NO production. Overall, our results demonstrate the existence of an endothelial-specific HSF (heat shock factor)-regulated transcriptional enhancer that mediates CALCRL expression. A better understanding of CALCRL gene regulation and the role of single-nucleotide polymorphisms in the modulation of CALCRL expression could provide important steps toward understanding the genetic regulation of shear stress signaling responses.

Aspirin Caused Intestinal Damage through FXR and ET-1 Signaling Pathways.

Aspirin is a non-steroidal, anti-inflammatory drug often used long term. However, long-term or large doses will cause gastrointestinal adverse reactions. To explore the mechanism of intestinal damage, we used non-targeted metabolomics; farnesoid X receptor (FXR) knockout mice, which were compared with wild-type mice; FXR agonists obeticholic acid (OCA) and chenodeoxycholic acid (CDCA); and endothelin-producing inhibitor estradiol to explore the mechanisms of acute and chronic intestinal injuries induced by aspirin from the perspective of molecular biology. Changes were found in the bile acids taurocholate acid (TCA) and tauro-β-muricholic acid (T-β-MCA) in the duodenum, and we detected a significant inhibition of FXR target genes. After additional administration of the FXR agonists OCA and CDCA, duodenal villus damage and inflammation were effectively improved. The results in the FXR knockout mice and wild-type mice showed that the overexpression of endothelin 1 (ET-1) was independent of FXR regulation after aspirin exposure, whereas CDCA was able to restore the activation of ET-1, which was induced by aspirin in wild-type mice in an FXR-dependent manner. The inhibition of ET-1 production could also effectively protect against small bowel damage. Therefore, the study revealed the key roles of the FXR and ET-1 pathways in acute and chronic aspirin-induced intestinal injuries, as well as strategies on alleviating aspirin-induced gastrointestinal injury by activating FXR and inhibiting ET-1 overexpression.

Combination of blockade of endothelin signalling and compensation of IGF1 expression protects the retina from degeneration.

Retinitis pigmentosa (RP) and macular dystrophy (MD) cause severe retinal dysfunction, affecting 1 in 4000 people worldwide. This disease is currently assumed to be intractable, because effective therapeutic methods have not been established, regardless of genetic or sporadic traits. Here, we examined a RP mouse model in which the Prominin-1 (Prom1) gene was deficient and investigated the molecular events occurring at the outset of retinal dysfunction. We extracted the Prom1-deficient retina subjected to light exposure for a short time, conducted single-cell expression profiling, and compared the gene expression with and without stimuli. We identified the cells and genes whose expression levels change directly in response to light stimuli. Among the genes altered by light stimulation, Igf1 was decreased in rod photoreceptor cells and astrocytes under the light-stimulated condition. Consistently, the insulin-like growth factor (IGF) signal was weakened in light-stimulated photoreceptor cells. The recovery of Igf1 expression with the adeno-associated virus (AAV) prevented photoreceptor cell death, and its treatment in combination with the endothelin receptor antagonist led to the blockade of abnormal glial activation and the promotion of glycolysis, thereby resulting in the improvement of retinal functions, as assayed by electroretinography. We additionally demonstrated that the attenuation of mammalian/mechanistic target of rapamycin (mTOR), which mediates IGF signalling, leads to complications in maintaining retinal homeostasis. Together, we propose that combinatorial manipulation of distinct mechanisms is useful for the maintenance of the retinal condition.

Regulation of involucrin and signalling pathway in scleroderma epidermal keratinocytes.

Systemic sclerosis is a complex disease characterized by the fibrosis and vasculopathy. We aimed to assess scleroderma by examining involucrin, an early terminal differentiation marker of epidermal keratinocytes. Immunolocalization of involucrin was performed in healthy controls and patients with scleroderma lesions by using an immunofluorescence (IF) assay. Normal and scleroderma keratinocytes were incubated in low-Ca basal-defined K-SFM overnight. Cells were pre-treated with Y-27632 (a Rho signalling pathway inhibitor) or interleukins (ILs), tumor necrosis factor-α (TNF-α), transforming growth factor β1 (TGF-β1), endothelin-1 (ET-1), interferon-γ (IFN)-γ, vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) - BB. The involucrin protein expression level was measured by western blot. Compared with the normal skin, involucrin was detected in the granular layer and the upper stratum spinosum in patients with scleroderma lesions. However, involucrin protein expression was decreased in cultured scleroderma keratinocytes. IL-6, IL-10, IL-17A, TNF-α, TGF-β1, ET-1, IFN-γ, VEGF165, and PDGF-BB increased involucrin expression in normal keratinocytes but decreased it in scleroderma keratinocytes. IFN-γ and IL-13 remarkably downregulated involucrin levels in normal and scleroderma keratinocytes, respectively, by Y-27632 intervention. Inflammatory cytokines, such as IL-6, IL-10, TGF-β1, ET-1, IFN-γ, VEGF, PDGF-BB, and Rho signalling pathway may be associated with the delayed epidermal differentiation in scleroderma.

Targeting the Endothelin-1 pathway to reduce invasion and chemoresistance in gallbladder cancer cells

BackgroundGallbladder cancer (GBC) is a prevalent and deadly biliary tract carcinoma, often diagnosed at advanced stages with limited treatment options. The 5-year survival rate varies widely from 4 to 60%, mainly due to differences in disease stage detection. With only a small fraction of patients having resectable tumors and a high incidence of metastasis, advanced GBC stages are characterized by significant chemoresistance. Identification of new therapeutic targets is crucial, and recent studies have shown that the Endothelin-1 (ET-1) signaling pathway, involving ETAR and/or ETBR receptors (ETRs), plays a crucial role in promoting tumor aggressiveness in various cancer models. Blocking one or both receptors has been reported to reduce invasiveness and chemoresistance in cancers like ovarian, prostate, and colon. Furthermore, transcriptomic studies have associated ET-1 levels with late stages of GBC; however, it remains unclear whether its signaling or its inhibition has implications for its aggressiveness. Although the role of ET-1 signaling in gallbladder physiology is minimally understood, its significance in other tumor models leads us to hypothesize its involvement in GBC malignancy.ResultsIn this study, we investigated the expression of ET-1 pathway proteins in three GBC cell lines and a primary GBC culture. Our findings demonstrated that both ETAR and ETBR receptors are expressed in GBC cells and tumor samples. Moreover, we successfully down-regulated ET-1 signaling using a non-selective ETR antagonist, Macitentan, which resulted in reduced migratory and invasive capacities of GBC cells. Additionally, Macitentan treatment chemosensitized the cells to Gemcitabine, a commonly used therapy for GBC.ConclusionFor the first time, we reveal the role of the ET-1 pathway in GBC cells, providing insight into the potential therapeutic targeting of its receptors to mitigate invasion and chemoresistance in this cancer with limited treatment options. These findings pave the way for further exploration of Macitentan or other ETR antagonists as potential therapeutic strategies for GBC management. In summary, our study represents a groundbreaking contribution to the field by providing the first evidence of the ET 1 pathway's pivotal role in modulating the behavior and aggressiveness of GBC cells, shedding new light on potential therapeutic targets.

Abstract 13928: Targeted Atrial Inhibition of Galphaq Signaling With Inhibitory Peptides Attenuates Fibrosis and Inducibility of Atrial Fibrillation in a Canine Heart Failure Model

Introduction: Endothelial dysfunction, a hallmark of heart failure (HF), is closely associated with atrial fibrillation (AF). However, the precise role of endothelial dysfunction in creating an atrial arrhythmogenic substrate is unknown. Endothelin-1 (ET-1) and its downstream Gα q signaling are significantly upregulated in the atria of patients with HF. We therefore hypothesized that ET-1-Gα q signaling contributes to adverse structural remodeling in the atria in the setting of HF. Hypothesis: Inhibition of atrial ET-1-Gα q signaling with Gα q inhibitory peptides (Gα q -ct) will attenuate the development of atrial fibrosis and AF inducibility in a HF model. Methods: Plasmids expressing Gα q -ct were injected and electroporated in the left atria of 4 dogs. LacZ or scrambled plasmids were used in 8 control dogs. HF was induced by ventricular tachypacing (VTP) at 240 bpm for 3 weeks. At terminal EP study, left atrial conduction vectors were recorded with high-density mapping and AF inducibility assessed. Left atrial fibrosis was quantified by Masson Trichrome. Results: All animals developed clinical HF (prolonged capillary refill time, ascites, reduced activity level) and LV systolic dysfunction by echocardiogram (LVEF 17.5±8.3% in Gα q -ct, 13.7±3.1% in controls, p=0.55). Conduction inhomogeneity was reduced in Gα q -ct animals (example of posterior left atrium recordings in Fig. A). AF was less inducible in Gα q -ct than control animals (4.8% of pacing attempts Vs 17.8%, p<0.001, Fig. B) and AF episodes were shorter (5.6±0.9 sec Vs 63.8±11.9 sec). Left atrial fibrosis was significantly attenuated in Gα q -ct animals Vs controls (Fig. C). Conclusions: Gα q signaling contributes to atrial fibrosis and subsequent AF susceptibility in VTP-induced HF, thereby highlighting an important role for ET-1 signaling in HF-related atrial remodeling. Future optimization of gene therapy targeting ET-1 signaling may lead to novel, mechanism-guided treatments for AF in the context of HF.

Gestational intermittent hypoxia induces endothelial dysfunction and hypertension in pregnant rats: role of endothelin type B receptor†.

Obstructive sleep apnea is a recognized risk factor for gestational hypertension, yet the exact mechanism behind this association remains unclear. Here, we tested the hypothesis that intermittent hypoxia, a hallmark of obstructive sleep apnea, induces gestational hypertension through perturbed endothelin-1 signaling. Pregnant Sprague-Dawley rats were subjected to normoxia (control), mild intermittent hypoxia (10.5% O2), or severe intermittent hypoxia (6.5% O2) from gestational days 10-21. Blood pressure was monitored. Plasma was collected and mesenteric arteries were isolated for myograph and protein analyses. The mild and severe intermittent hypoxia groups demonstrated elevated blood pressure, reduced plasma nitrate/nitrite, and unchanged endothelin-1 levels compared to the control group. Western blot analysis revealed decreased expression of endothelin type B receptor and phosphorylated endothelial nitric oxide synthase, while the levels of endothelin type A receptor and total endothelial nitric oxide synthase remained unchanged following intermittent hypoxia exposure. The contractile responses to potassium chloride, phenylephrine, and endothelin-1 were unaffected in endothelium-denuded arteries from mild and severe intermittent hypoxia rats. However, mild and severe intermittent hypoxia rats exhibited impaired endothelium-dependent vasorelaxation responses to endothelin type B receptor agonist IRL-1620 and acetylcholine compared to controls. Endothelium denudation abolished IRL-1620-induced vasorelaxation, supporting the involvement of endothelium in endothelin type B receptor-mediated relaxation. Treatment with IRL-1620 during intermittent hypoxia exposure significantly attenuated intermittent hypoxia-induced hypertension in pregnant rats. This was associated with elevated circulating nitrate/nitrite levels, enhanced endothelin type B receptor expression, increased endothelial nitric oxide synthase activation, and improved vasodilation responses. Our data suggested that intermittent hypoxia exposure during gestation increases blood pressure in pregnant rats by suppressing endothelin type B receptor-mediated signaling, providing a molecular mechanism linking intermittent hypoxia and gestational hypertension.

Endothelin mediates sex-differences in acclimation to high salt diet in rats

IntroductionCurrent understanding of sodium (Na+) handling is based on studies done primarily in males. Contrary to the gradual increase in high salt (HS) induced natriuresis over 3–5 days in males, female Sprague Dawley (SD) rats have a robust natriuresis after 1 day of HS. Renal endothelin-1 (ET-1) signaling, through ET receptor A and B, is an important natriuretic pathway and was implicated in our previous dietary salt acclimation studies, however, the contribution of ET receptors to sex-differences in acclimation to dietary Na+ challenges has yet to be clarified. We hypothesized that ET receptors mediate the augmented natriuretic capacity of female rats in response to a HS diet.MethodsTo test our hypothesis, male and female SD rats were implanted with telemeters and randomly assigned to treatment with A-182086, a dual ETA and ETB receptor antagonist, or control. 24-h urine samples were collected and assessed for electrolytes and ET-1. Studies were performed on a normal salt (NS, 0.3% NaCl) diet and after challenging rats with HS (4% NaCl) diet for 1 day.ResultsWe found that A-182086 increased blood pressure in male and female SD rats fed either diet. Importantly, A-182086 eliminated sex-differences in natriuresis on NS and HS. In particular, A-182086 promotes HS-induced natriuresis in male rats rather than attenuating the natriuretic capacity of females. Further, the sex-difference in urinary ET-1 excretion in NS-fed rats was eliminated by A-182086.ConclusionIn conclusion, ET receptors are crucial for mediating sex-difference in the natriuretic capacity primarily through their actions in male rats.

Insulin-mediated endothelin signaling is antiviral during West Nile virus infection.

Arboviruses, particularly those transmitted by mosquitoes, pose a significant threat to humans and are an increasing concern because of climate change, human activity, and expanding vector-competent populations. West Nile virus is of significant concern as the most frequent mosquito-borne disease transmitted annually within the continental United States. Here, we identify a previously uncharacterized signaling pathway that impacts West Nile virus infection, namely endothelin signaling. Additionally, we demonstrate that we can successfully translate results obtained from D. melanogaster into the more relevant human system. Our results add to the growing field of insulin-mediated antiviral immunity and identify potential biomarkers or intervention targets to better address West Nile virus infection and severe disease.