Mechanism of endoplasmic reticulum stress-induced vascular endothelial dysfunction

PDE4B abrogation extenuates angiotensin II-induced endothelial dysfunction related to hypertension through up-regulation of AMPK/Sirt1/Nrf2/ARE signaling

Endothelial dysfunction is commonly perceived as a precursor in the process of hypertension, a severe cardiovascular disorder. Phosphodiesterase 4B (PDE4B) inactivation has been proposed to exert cardioprotective effects and prevent pulmonary hypertension. However, the role of PDE4B in endothelial dysfunction in hypertension remains inexplicit, which will be investigated in the present work. In angiotensin II (Ang II)-induced human umbilical vein endothelial cells (HUVECs), RT-qPCR and Western blotting were used to analyze PDE4B expression. CCK-8 method was used to detect cell viability. Flow cytometry assay and Caspase 3 assay kit were used to detect cellular apoptotic level. Wound healing and tube formation assays were respectively used to detect cell migration and angiogenesis. Western blotting and corresponding assay kits were respectively used to analyze the expressions and contents of endothelial dysfunction markers. JC-1 assay, RT-qPCR and relevant assay kit were respectively used to detect mitochondrial membrane potential (ΔΨm), quantify mitochondrial DNA (mtDNA) copy number and mitochondrial permeability transition pore (mPTP) opening. Besides, Western blotting was used to analyze the expressions of endoplasmic reticulum stress (ERS) and AMP-activated protein kinase (AMPK)/sirtuin 1 (Sirt1)/nuclear factor-erythroid 2 related factor 2 (Nrf2)/antioxidant response element (ARE) signaling-associated proteins. PDE4B expression was increased in Ang II- induced HUVECs. PDE4B knockdown promoted the viability, migration, angiogenesis while inhibiting the apoptosis, endothelial dysfunction, ERS and mitochondrial damage in Ang II-induced HUVECs. Additionally, PDE4B silence activated AMPK/Sirt1/Nrf2/ARE pathway and AMPK inhibitor Compound C (CC) partially reversed the effects of PDE4B down-regulation on Ang II-induced HUVECs. Conclusively, PDE4B inhibition might protect against Ang II-induced endothelial dysfunction in HUVECs via up-regulating AMPK/Sirt1/Nrf2/ARE pathway, which might be mediated by the suppression of ERS and mitochondrial damage.

Endoplasmic reticulum stress is attenuated by glycolysis in lymphatic malformations

BACKGROUND

This study aims to investigate the role of endoplasmic reticulum stress (ER stress) in human dermal lymphatic endothelial cells (HDLECs) and lymphatic malformations (LMs) and its relationship with aerobic glycolysis and inflammation.

METHODS

The proliferation and apoptosis of HDLECs were examined with lipopolysaccharide (LPS) treatment. ER stress-associated proteins and glycolysis-related markers were detected by western blot. Glycolysis indexes were detected by seahorse analysis and lactic acid production assay kits. Immunohistochemistry was used to reveal the ER stress state of lymphatic endothelial cells (LECs) in LMs.

RESULTS

LPS induced ER stress in HDLECs but did not trigger detectable apoptosis. Intriguingly, LPS-treated HDLECs also showed increased glycolysis flux. Knockdown of Hexokinase 2, a key enzyme for aerobic glycolysis, significantly inhibited the ability of HDLECs to resist ER stress-induced apoptosis. Moreover, compared to normal skin, glucose-regulated protein 78 (GRP78/BIP), and phosphorylation protein kinase R-like kinase (p-PERK), two key ER stress-associated markers, were upregulated in LECs of LMs, which was correlated with the inflected state. In addition, excessively activated ER stress inhibited the progression of LMs in rat models.

CONCLUSIONS

These data indicate that glycolysis could rescue activated ER stress in HDLECs, which is required for the accelerated development of LMs.

IMPACT

Inflammation enhances both ER stress and glycolysis in LECs while glycolysis is required to attenuate the pro-apoptotic effect of ER stress. Endoplasmic reticulum (ER) stress is activated in lymphatic endothelial cells (LECs) of LMs, especially in inflammatory condition. The expression of ER stress-related proteins is increased in LMs and correlated with Hexokinase 2 expression. Pharmacological activation of ER stress suppresses the formation of LM lesions in the rat model. ER stress may be a promising and effective therapeutic target for the treatment of LMs.

Endoplasmic Reticulum Stress Induces Vasodilation in Liver Vessels That Is Not Mediated by Unfolded Protein Response

There is a growing body of evidence that ER stress and the unfolded protein response (UPR) play a key role in numerous diseases. Impaired liver perfusion and ER stress often accompany each other in liver diseases. However, the exact impact of ER stress and UPR on the hepatic perfusion is not fully understood. The aim of this study was to disclose the effect of ER stress and UPR on the size of liver vessels and on the levels of Ca2+ and nitric oxide (NO), critical regulators of vascular tonus. This study was carried out in precisely cut liver tissue slices. Confocal microscopy was used to create 3D images of vessels. NO levels were determined either using either laser scan microscopy (LSM) in cells or by NO-analyser in medium. Ca2+ levels were analysed by LSM. We show that tunicamycin, an inducer of ER stress, acts similarly with vasodilator acetylcholine. Both exert a similar effect on the NO and Ca2+ levels; both induce significant vasodilation. Notably, this vasodilative effect persisted despite individual inhibition of UPR pathways-ATF-6, PERK, and IRE1-despite confirming the activation of UPR. Experiments with HUVEC cells showed that elevated NO levels did not result from endothelial NO synthase (eNOS) activation. Our study suggests that tunicamycin-mediated ER stress induces liver vessel vasodilation in an NO-dependent manner, which is mediated by intracellular nitrodilator-activatable NO store (NANOS) in smooth muscle cells rather than by eNOS.

Pridopidine subtly ameliorates motor skills in a mouse model for vanishing white matter

The leukodystrophy vanishing white matter (VWM) is characterized by chronic and episodic acute neurological deterioration. Curative treatment is presently unavailable. Pathogenic variants in the genes encoding eukaryotic initiation factor 2B (eIF2B) cause VWM and deregulate the integrated stress response (ISR). Previous studies in VWM mouse models showed that several ISR-targeting compounds ameliorate clinical and neuropathological disease hallmarks. It is unclear which ISR components are suitable therapeutic targets. In this study, effects of 4-phenylbutyric acid, tauroursodeoxycholic acid, or pridopidine (PDPD), with ISR targets upstream or downstream of eIF2B, were assessed in VWM mice. In addition, it was found that the composite ataxia score represented motor decline of VWM mice more accurately than the previously used neuroscore. 4-phenylbutyric acid and tauroursodeoxycholic acid did not improve VWM disease hallmarks, whereas PDPD had subtle beneficial effects on motor skills. PDPD alone does not suffice as treatment in VWM mice but may be considered for combination therapy. Also, treatments aimed at ISR components upstream of eIF2B do not improve chronic neurological deterioration; effects on acute episodic decline remain to be investigated.

Ac-SDKP attenuates ER stress-stimulated collagen production in cardiac fibroblasts by inhibiting CHOP-mediated NF-κB expression

Inflammation and cardiac fibrosis are prevalent pathophysiologic conditions associated with hypertension, cardiac remodeling, and heart failure. Endoplasmic reticulum (ER) stress triggers the cells to activate unfolded protein responses (UPRs) and upregulate the ER stress chaperon, enzymes, and downstream transcription factors to restore normal ER function. The mechanisms that link ER stress-induced UPRs upregulation and NF-κB activation that results in cardiac inflammation and collagen production remain elusive. N-Acetyl-Ser-Asp-Lys-Pro (Ac-SDKP), a natural tetrapeptide that negatively regulates inflammation and fibrosis, has been reported. Whether it can inhibit ER stress-induced collagen production in cardiac fibroblasts remains unclear. Thus, we hypothesized that Ac-SDKP attenuates ER stress-stimulated collagen production in cardiac fibroblasts by inhibiting CHOP-mediated NF-κB expression. We aimed to study whether Ac-SDKP inhibits tunicamycin (TM)-induced ER stress signaling, NF-κB signaling, the release of inflammatory cytokine interleukin-6, and collagen production in human cardiac fibroblasts (HCFs). HCFs were pre-treated with Ac-SDKP (10 nM) and then stimulated with TM (0.25 μg/mL). We found that Ac-SDKP inhibits TM-induced collagen production by attenuating ER stress-induced UPRs upregulation and CHOP/NF-κB transcriptional signaling pathways. CHOP deletion by specific shRNA maintains the inhibitory effect of Ac-SDKP on NF-κB and type-1 collagen (Col-1) expression at both protein and mRNA levels. Attenuating ER stress-induced UPR sensor signaling by Ac-SDKP seems a promising therapeutic strategy to combat detrimental cardiac inflammation and fibrosis.

Empagliflozin reduces endoplasmic reticulum stress associated TXNIP/NLRP3 activation in tunicamycin-stimulated aortic endothelial cells

Sodium-glucose cotransporter 2 inhibitors (SGLT2i) have proven to be of therapeutic significance for cardiovascular diseases beyond the treatment of type 2 diabetes. Recent studies have demonstrated the beneficial effects of SGLT2i on endothelial cell (EC) dysfunction, but the underlying cellular mechanisms remain to be clarified. In this study, we sought to understand the effect of empagliflozin (EMPA; Jardiance®) on cell homeostasis and endoplasmic reticulum (ER) stress signaling. ER stress was induced by tunicamycin (Tm) in human abdominal aortic ECs treated with EMPA over 24 h. Tm-induced ER stress caused increases in the protein expression of thioredoxin interacting protein (TXNIP), NLR-family pyrin domain-containing protein 3 (NLRP3), C/EBP homologous protein (CHOP), and in the ratio of phospho-eIF2α/eIF2α. EMPA (50-100 µM) resulted in a dampened downstream activation of ER stress as seen by the reduced expression of CHOP and TXNIP/NLRP3 in a dose-dependent manner. Nuclear factor erythroid 2-related factor 2 (nrf2) translocation was also attenuated in EMPA-treated ECs. These results suggest that EMPA improves redox signaling under ER stress which in turn attenuates the activation of TXNIP/NLRP3.

Portulaca Oleracea L. (Purslane) Extract Protects Endothelial Function by Reducing Endoplasmic Reticulum Stress and Oxidative Stress through AMPK Activation in Diabetic Obese Mice

Portulaca oleracea L. (purslane) is a food and a traditional drug worldwide. It exhibits anti-inflammatory, anti-oxidative, anti-tumor, and anti-diabetic bioactivities; but its activity on diabetic-associated endothelial dysfunction is unknown. This study aimed to investigate the effect of purslane on endothelial function and the underlying mechanisms. Male C57BL/6 mice had 14-week ad libitum access to a high-fat rodent diet containing 60% kcal% fat to induce obesity and diabetes whereas purslane extract (200 mg/kg/day) was administered during the last 4 weeks via intragastric gavage. Primary rat aortic endothelial cells and isolated mouse aortas were cultured with a risk factor, high glucose or tunicamycin, together with purslane extract. By ESI-QTOF-MS/MS, flavonoids and their glycoside products were identified in the purslane extract. Exposure to high glucose or tunicamycin impaired acetylcholine-induced endothelium-dependent relaxations in aortas and induced endoplasmic reticulum (ER) stress and oxidative stress with the downregulation of 5' AMP-activated protein kinase (AMPK)/ endothelial nitric oxide synthase (eNOS) signaling. Co-incubation with purslane significantly ameliorated these impairments. The effects of purslane were abolished by Compound C (AMPK inhibitor). Four-week purslane treatment ameliorated aortic relaxations, ER stress, and oxidative stress in diabetic obese mice. This study supported that purslane protected endothelial function, and inhibited ER stress and oxidative stress in vasculature through AMPK/eNOS activation, revealing its therapeutic potential against vascular complications in diabetes.

Can endoplasmic reticulum stress observed in the PTZ-kindling model seizures be prevented with TUDCA and 4-PBA?

Epilepsy is a chronic neurological disease with recurrent seizures. Increasing evidence suggests that endoplasmic reticulum (ER) stress may play a role in the pathogenesis of epilepsy. We aimed to investigate the effects of Tauroursodeoxycholic acid (TUDCA) and 4-phenyl-butyric acid (4-PBA), which are known to suppress ER stress, on developed seizures in terms of markers of ER stress, oxidative stress, and apoptosis. The pentylenetetrazole (PTZ) kindling model was induced in Wistar albino rats (n = 48) by administering 35 mg/kg PTZ intraperitoneally (I.P.) every other day for 1 month. TUDCA and 4-PBA were administered via I.P. at a dose of 500 mg/kg dose. ER stress, apoptosis, and oxidative stress were determined in the hippocampus tissues of animals in all groups. Immunohistochemistry, qRT-PCR, ELISA, and Western Blot analyzes were performed to determine the efficacy of treatments. Expressions of ATF4, ATF6, p-JNK1/2, Cleaved-Kaspase3, and Caspase12 significantly increased in PTZ-kindled seizures compared to the control group. Increased NOX2 and MDA activity in the seizures were measured. In addition, stereology analyzes showed an increased neuronal loss in the PTZ-kindled group. qRT-PCR examination showed relative mRNA levels of CHOP. Accordingly, TUDCA and 4-PBA treatment suppressed the expressions of ATF4, ATF6, Cleaved-Caspase3, Kaspase12, NOX2, MDA, and CHOP in TUDCA + PTZ and 4-PBA + PTZ groups. ER stress-induced oxidative stress and apoptosis by reducing neuronal loss and degeneration were also preserved in these groups. Our data show molecularly that TUDCA and 4-PBA treatment can suppress the ER stress process in epileptic seizures.

Protection against cancer therapy-induced cardiovascular injury by planed-derived polyphenols and nanomaterials

Cancer therapy-induced heart injury is a significant concern for cancer patients undergoing chemotherapy, radiotherapy, immunotherapy, and also targeted molecular therapy. The use of these treatments can lead to oxidative stress and cardiomyocyte damage in the heart, which can result in heart failure and other cardiac complications. Experimental studies have revealed that chemotherapy drugs such as doxorubicin and cyclophosphamide can cause severe side effects such as cardiac fibrosis, electrophysiological remodeling, chronic oxidative stress and inflammation, etc., which may increase risk of cardiac disorders and attacks for patients that underwent chemotherapy. Similar consequences may also be observed for patients that undergo radiotherapy for left breast or lung malignancies. Polyphenols, a group of natural compounds with antioxidant and anti-inflammatory properties, have shown the potential in protecting against cancer therapy-induced heart injury. These compounds have been found to reduce oxidative stress, necrosis and apoptosis in the heart, thereby preserving cardiac function. In recent years, nanoparticles loaded with polyphenols have also provided for the delivery of these compounds and increasing their efficacy in different organs. These nanoparticles can improve the bioavailability and efficacy of polyphenols while minimizing their toxicity. This review article summarizes the current understanding of the protective effects of polyphenols and nanoparticles loaded with polyphenols against cancer therapy-induced heart injury. The article discusses the mechanisms by which polyphenols protect the heart, including antioxidant and anti-inflammation abilities. The article also highlights the potential benefits of using nanoparticles for the delivery of polyphenols.

Novel pharmacological approaches in abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is a severe vascular disease and a major public health issue with an unmet medical need for therapy. This disease is featured by a progressive dilation of the abdominal aorta, boosted by atherosclerosis, ageing, and smoking as major risk factors. Aneurysm growth increases the risk of aortic rupture, a life-threatening emergency with high mortality rates. Despite the increasing progress in our knowledge about the etiopathology of AAA, an effective pharmacological treatment against this disorder remains elusive and surgical repair is still the unique available therapeutic approach for high-risk patients. Meanwhile, there is no medical alternative for patients with small aneurysms but close surveillance. Clinical trials assessing the efficacy of antihypertensive agents, statins, doxycycline, or anti-platelet drugs, among others, failed to demonstrate a clear benefit limiting AAA growth, while data from ongoing clinical trials addressing the benefit of metformin on aneurysm progression are eagerly awaited. Recent preclinical studies have postulated new therapeutic targets and pharmacological strategies paving the way for the implementation of future clinical studies exploring these novel therapeutic strategies. This review summarises some of the most relevant clinical and preclinical studies in search of new therapeutic approaches for AAA.

Interleukin-1β Disruption Protects Male Mice From Heart Failure With Preserved Ejection Fraction Pathogenesis

Background Heart failure with preserved ejection fraction (HFpEF) is a significant unmet need in cardiovascular medicine and remains an untreatable cardiovascular disease. The role and mechanism of interleukin-1β in HFpEF pathogenesis are poorly understood. Methods and Results C57/Bl6J and interleukin-1β-/- male mice were randomly divided into 4 groups. Groups 1 and 2: C57/Bl6J and interleukin-1β-/- mice were fed a regular diet for 4 months and considered controls. Groups 3 and 4: C57/Bl6 and interleukin-1β-/- mice were fed a high-fat diet with N[w]-nitro-l-arginine methyl ester (endothelial nitric oxide synthase inhibitor, 0.5 g/L) in the drinking water for 4 months. We measured body weight, blood pressure, diabetes status, cardiac function/hypertrophy/inflammation, fibrosis, vascular endothelial function, and signaling. C57/Bl6 fed a high-fat diet and N[w]-nitro-l-arginine methyl ester in the drinking water for 4 months developed HFpEF pathogenesis characterized by obesity, diabetes, hypertension, cardiac hypertrophy, lung edema, low running performance, macrovascular and microvascular endothelial dysfunction, and diastolic cardiac dysfunction but no change in cardiac ejection fraction compared with control mice. Interestingly, the genetic disruption of interleukin-1β protected mice from HFpEF pathogenesis through the modulation of the inflammation and endoplasmic reticulum stress mechanisms. Conclusions Our data suggest that interleukin-1β is a critical driver in the development of HFpEF pathogenesis, likely through regulating inflammation and endoplasmic reticulum stress pathways. Our findings provide a potential therapeutic target for HFpEF treatment.

Aging reduces calreticulin expression and alters spontaneous calcium signals in astrocytic endfeet of the mouse dorsolateral striatum

Aging-related impairment of the blood brain barrier (BBB) and neurovascular unit (NVU) increases the risk for neurodegeneration. Among various cells that participate in BBB and NVU function, calcium signals in astrocytic endfeet are crucial for maintaining BBB and NVU integrity. To assess if aging is associated with altered calcium signals within astrocytic endfeet of the dorsolateral striatum (DLS), we expressed GCaMP6f in DLS astrocytes of young (3-4 months), middle-aged (12-15 months) and aging (20-30 months) mice. Compared to endfeet in young mice, DLS endfeet in aging mice demonstrated decreased calreticulin expression, and alterations to both spontaneous membrane-associated and mitochondrial calcium signals. While young mice required both extracellular and endoplasmic reticulum calcium sources for endfoot signals, middle-aged and aging mice showed heavy dependence on endoplasmic reticulum calcium. Thus, astrocytic endfeet show significant changes in calcium buffering and sources throughout the lifespan, which is important for understanding mechanisms by which aging impairs the BBB and NVU.

Endoplasmic Reticulum Stress and Renin-Angiotensin System Crosstalk in Endothelial Dysfunction

BACKGROUND

Vascular endothelial dysfunction (VED) significantly results in catastrophic cardiovascular diseases with multiple aetiologies. Variations in vasoactive peptides, including angiotensin II and endothelin 1, and metabolic perturbations like hyperglycaemia, altered insulin signalling, and homocysteine levels result in pathogenic signalling cascades, which ultimately lead to VED. Endoplasmic reticulum (ER) stress reduces nitric oxide availability, causes aberrant angiogenesis, and enhances oxidative stress pathways, consequently promoting endothelial dysfunction. Moreover, the renin-angiotensin system (RAS) has widely been acknowledged to impact angiogenesis, endothelial repair and inflammation. Interestingly, experimental studies at the preclinical level indicate a possible pathological link between the two pathways in the development of VED. Furthermore, pharmacological modulation of ER stress ameliorates angiotensin-II mediated VED as well as RAS intervention either through inhibition of the pressor arm or enhancement of the depressor arm of RAS, mitigating ER stress-induced endothelial dysfunction and thus emphasizing a vital crosstalk.

CONCLUSION

Deciphering the pathway overlap between RAS and ER stress may open potential therapeutic avenues to combat endothelial dysfunction and associated diseases. Several studies suggest that alteration in a component of RAS may induce ER stress or induction of ER stress may modulate the RAS components. In this review, we intend to elaborate on the crosstalk of ER stress and RAS in the pathophysiology of VED.

Chitooligosaccharide prevents vascular endothelial cell apoptosis by attenuation of endoplasmic reticulum stress via suppression of oxidative stress through Nrf2-SOD1 up-regulation

CONTEXT

Endoplasmic reticulum (ER) stress contributes to endothelium pathological conditions. Chitooligosaccharides (COS) have health benefits, but their effect on endothelial cells is unknown. We demonstrate for the first time a protective effect of COS against ER-induced endothelial cell damage.

OBJECTIVE

To evaluate the protective effect of COS on ER stress-induced apoptosis in endothelial cells.

MATERIAL AND METHODS

Endothelial (EA.hy926) cells were pre-treated with COS (250 or 500 μg/mL) for 24 h, and then treated with 0.16 μg/mL of Tg for 24 h and compared to the untreated control. Apoptosis and necrosis were detected by Annexin V-FITC/propidium iodide co-staining. Reactive oxygen species (ROS) were measured with the DCFH₂-DA and DHE probes. The protective pathway and ER stress markers were evaluated by reverse transcription-polymerase chain reaction, western blot, and immunofluorescence analyses.

RESULTS

COS attenuated ER stress-induced cell death. The viability of EA.hy926 cells treated with Tg alone was 44.97 ± 1% but the COS pre-treatment increased cells viability to 74.74 ± 3.95% in the 250 μg/mL COS and 75.34 ± 2.4% in the 500 μg/mL COS treatments. Tg induced ER stress and ROS, which were associated with ER stress-mediated death. Interestingly, COS reduced ROS by upregulating nuclear factor-E2-related factor 2 (Nrf2), and the oxidative enzymes, superoxide dismutase1 (SOD1) and catalase. COS also suppressed up-regulation of the ER-related apoptosis protein, CHOP induced by Tg.

CONCLUSIONS

COS protected against ER stress-induced apoptosis in endothelial cells by suppressing ROS and up-regulation Nrf2 and SOD1. These findings support the use of COS to protect endothelial cells.

Shrimp Lipid Prevents Endoplasmic Reticulum-Mediated Endothelial Cell Damage

Shrimp contains a fat that benefits cardiovascular function and may help in the prevention of diseases. The stress of essential cellular organelle endoplasmic reticulum (ER) is linked to endothelial dysfunction and damage. This research aimed at investigating the effect of shrimp lipid (SL) on endothelial cells in response to ER stress, as well as the underlying mechanisms. Human endothelial cells were pretreated with SL (250 and 500 μg/mL) for 24 h, and treated with 0.16 μg/mL of Thapsigargin (Tg) for 24 h. The apoptosis and necrosis were detected by Hoechst 33342/propidium iodide (PI) co-staining. Cellular signaling pathways and ER stress markers were evaluated by Western blot analysis and immunofluorescence. SL protected against ER-induced endothelial cell apoptosis. According to the results, the viability of EA.hy926 cells treated with Tg alone was 44.97 ± 1%, but SL (250 μg/mL) pretreatment increased cell viability to 77.26 ± 3.9%, and SL (500 μg/mL) increased to 72.42 ± 4.3%. SL suppressed the increase in ER stress regulator glucose-regulated protein 78 (GRP78) and attenuated the RNA-dependent protein kinase-like ER eukaryotic initiation factor-2α kinase (PERK) and inositol-requiring ER-to-nucleus signaling protein 1 (IRE1) pathways. SL could inhibit cell damage by reducing the ER-related apoptosis protein, C/EBPα-homologous protein (CHOP), induced by ER stress. Taken together, we found the protective effect and mechanism of SL in protecting ER stress-induced endothelial cell apoptosis through suppression of the ER stress pathway. The findings may support the potential use of SL as an approach with a protective effect on endothelial cells.

Role of endoplasmic reticulum stress in impaired neonatal lung growth and bronchopulmonary dysplasia

Myeloperoxidase (MPO), oxidative stress (OS), and endoplasmic reticulum (ER) stress are increased in the lungs of rat pups raised in hyperoxia, an established model of bronchopulmonary dysplasia (BPD). However, the relationship between OS, MPO, and ER stress has not been examined in hyperoxia rat pups. We treated Sprague-Dawley rat pups with tunicamycin or hyperoxia to determine this relationship. ER stress was detected using immunofluorescence, transcriptomic, proteomic, and electron microscopic analyses. Immunofluorescence observed increased ER stress in the lungs of hyperoxic rat BPD and human BPD. Proteomic and morphometric studies showed that tunicamycin directly increased ER stress of rat lungs and decreased lung complexity with a BPD phenotype. Previously, we showed that hyperoxia initiates a cycle of destruction that we hypothesized starts from increasing OS through MPO accumulation and then increases ER stress to cause BPD. To inhibit ER stress, we used tauroursodeoxycholic acid (TUDCA), a molecular chaperone. To break the cycle of destruction and reduce OS and MPO, we used N-acetyl-lysyltyrosylcysteine amide (KYC). The fact that TUDCA improved lung complexity in tunicamycin- and hyperoxia-treated rat pups supports the idea that ER stress plays a causal role in BPD. Additional support comes from data showing TUDCA decreased lung myeloid cells and MPO levels in the lungs of tunicamycin- and hyperoxia-treated rat pups. These data link OS and MPO to ER stress in the mechanisms mediating BPD. KYC's inhibition of ER stress in the tunicamycin-treated rat pup's lung provides additional support for the idea that MPO-induced ER stress plays a causal role in the BPD phenotype. ER stress appears to expand our proposed cycle of destruction. Our results suggest ER stress evolves from OS and MPO to increase neonatal lung injury and impair growth and development. The encouraging effect of TUDCA indicates that this compound has the potential for treating BPD.

The Effect of Tauroursodeoxycholic Acid (TUDCA) Treatment on Pregnancy Outcomes and Vascular Function in a Rat Model of Advanced Maternal Age

Advanced maternal age (≥35 years) increases the risk of vascular complications in pregnancy that can result in fetal growth restriction and preeclampsia. Endoplasmic reticulum (ER) stress has been linked to adverse pregnancy outcomes in these complicated pregnancies. However, the role of ER stress in advanced maternal age is not known. We hypothesize that increased ER stress contributes to altered vascular function and poor pregnancy outcomes, and that treatment with the ER-stress inhibitor TUDCA will improve pregnancy outcomes. First, young and aged non-pregnant/pregnant rats were used to assess ER stress markers in mesenteric arteries; mesenteric artery phospho-eIF2α and CHOP expression were increased in aged dams compared to young dams. In a second study, young and aged control and TUDCA-treated dams were studied on gestational day (GD) 20 (term = 22 days). TUDCA treatment was provided via the drinking water throughout pregnancy (GD0-GD20; calculated dose of 150 mg/kg/day TUDCA). ER stress markers were quantified in mesenteric arteries, blood pressure was measured, pregnancy outcomes were recorded, mesenteric and main uterine arteries were isolated and vascular function was assessed by wire myography. Aged dams had increased phospho-eIF2α and CHOP expression, reduced fetal weight, reduced litter size, and impaired uterine artery relaxation. In the aged dams, TUDCA treatment reduced phospho-eIF2α and CHOP expression, reduced blood pressure, improved fetal body weight, and tended to improve uterine artery function compared to control-treated aged dams. In conclusion, our data illustrate the role of ER stress, as well as TUDCA as a potential therapeutic that may benefit pregnancy outcomes in advanced maternal age.

Neuroprotective Effects of Tauroursodeoxicholic Acid Involves Vascular and Glial Changes in Retinitis Pigmentosa Model

Purpose

Retinitis pigmentosa is primarily characterized by a massive photoreceptor loss. But a global retinal remodeling occurs in later stages of the disease. At that phase, glial cells and retinal vasculature are also strongly affected. The main aim of the present work is to assess if the bile acid Tauroursodeoxicholic acid (TUDCA), which has a demonstrated neuroprotective effect in numerous neurodegenerative diseases, is able to prevent glial and vascular degeneration in the P23H rat retina.

Methods

Homozygous P23H (line 3) animals were injected weekly with a TUDCA (500 mg/kg, i.p.) or vehicle solution, from the postnatal day (P) 21 to P120. Sprague-Dawley rats (SD) were used as control. Retinal cross-sections and wholemounts were immunostained using different glial and vascular markers and visualized with confocal microscopy. Retinal blood vessels were stained with nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase histochemistry and retinal vascular networks were drawn by hand using a camera lucida.

Results

At P120, the photoreceptor degeneration observed in P23H rats was accompanied by a reduction in the vascular network density and complexity at the deep capillary plexus. In addition, astrocytes showed gliotic features and the outer processes of Müller cells displayed an aberrant distribution in ring-shaped structures. When treated with TUDCA, P23H rats displayed better-preserved vessels and capillary loops in the deep capillary plexus which are associated with the partial preservation of photoreceptors. TUDCA treatment also increased the number of astrocytes and reduced the presence of Müller cell process clusters in the outer retina.

Conclusion

This work suggests that, besides its neuroprotective effect on photoreceptor cells, TUDCA treatment also protects from vascular and glial degeneration, a fact that encourages the use of TUDCA as a powerful therapy for neurodegenerative diseases.

Insulin-like growth factor-1: A potential target for bronchopulmonary dysplasia treatment (Review)

Bronchopulmonary dysplasia (BPD) is a common respiratory disorder among preterm infants, particularly low-birth-weight infants (LBWIs) and very-low-birth-weight infants (VLBWIs). Although BPD was first reported 50 years ago, no specific drugs or efficient measures are yet available for prevention or treatment. Insulin-like growth factor-1 (IGF-1) belongs to the insulin family. It promotes mitosis and stimulates cell proliferation and DNA synthesis, the primary factors involved in pulmonary development during the fetal and postnatal periods. Several studies have reported that IGF-1 exerts certain effects on BPD genesis and progression by regulating BPD-related biological processes. In addition, exogenous addition of IGF-1 can alleviate lung inflammation, cell apoptosis and eliminate alveolar development disorders in children with BPD. These findings suggest that IGF-1 could be a new target for treating BPD. Here, we summarize and analyze the definition, pathogenesis, and research status of BPD, as well as the pathogenesis of IGF-1 in BPD and the latest findings in related biological processes.

Disrupting Interleukin 12 Improves Microvascular Endothelial Function in Type 2 Diabetes Through ER Stress CHOP and Oxidative Stress Mechanisms

PURPOSE

Vascular endothelial dysfunction is well established in type 2 diabetes. Interleukin-12 (IL-12) and endoplasmic reticulum (ER) stress are up-regulated in type 2 diabetic patients and animal models of type 2 diabetes. However, the role and underlying mechanisms of IL-12 and the ER stress CHOP in endothelial dysfunction are not fully understood.

METHODS

We generated double knockout mice between db^-/db^- and p40IL-12^-/- mice (db^-/db^{-p40-IL-12-/-}) and endoplasmic (ER) stress-CHOP^-/- mice (db^-/db^-CHOP-/-). We performed a glucose tolerance test (GTT) to determine the effect of IL-12 and ER stress CHOP on glucose metabolism. We assessed the endothelial function and determined the phosphorylation level of eNOS, Akt, AMPK, and the expression of ER stress (CHOP, BIP), and oxidative stress (Nox2 and Nox4 and NADPH oxidase activity).

RESULTS

The results showed that GTT was improved in db-/db^{-p40-IL-12-/-} and db^-/db^-CHOP-/- suggesting IL-12 and CHOP as parts of a mechanism involved in the development of type 2 diabetes. The microvascular endothelial dysfunction in db^-/db^- mouse is associated with decreased phosphorylated eNOS, Akt, AMPK, and increased CHOP, BIP, Nox2, and Nox4 expressions. Interestingly, disrupting IL-12 and ER stress CHOP in db^-/db^- mice significantly improved endothelial function, increased survival markers expression and decreased ER and oxidative stress.

CONCLUSION

Using a genetic approach, these findings provide evidence that IL-12 and ER stress CHOP play a significant role in microvascular endothelial dysfunction in type 2 diabetes.

Effects of Escitalopram on Endoplasmic Reticulum Stress and Oxidative Stress Induced by Tunicamycin

Background: Major depressive disorder (MDD) was reported to be associated with endoplasmic reticulum stress (ERS) combined with oxidative stress (OS) (ERS/OS). Here, we aimed to investigate the effects of escitalopram (ESC) on blood-brain barrier (BBB) permeability and ERS/OS-related pathways in brain microvascular endothelial cells (bEnd.3 cells) induced by tunicamycin (TM).

Methods: bEnd.3 cells were divided into four groups: control, TM, ESC, and ESC + TM groups. CCK-8 and flow cytometry were used to detect cell survival and apoptosis, respectively. The expression levels of proteins involved in cell permeability and ERS/OS-related pathways were assessed by western blot and immunofluorescence. Malondialdehyde (MDA) concentration and superoxide dismutase (SOD) activity were determined by commercial kits.

Results: We revealed that TM-induced bEnd.3 cells exhibited remarkably decreased viability and increased apoptosis rate, while ESC treatment reversed these changes. Additionally, TM treatment resulted in markedly increased PERK, GRP78, ATF6, XBP1, and CHOP protein expression levels. On the contrary, the expression of PERK, GRP78, XBP1, and CHOP was obviously reduced in TM-induced bEnd.3 cells after ESC treatment. Moreover, TM significantly reduced the expression of p-eNOS and P-gp and increased the expression of CaMKII and MMP9 compared with the control group. However, ESC reversed these changes in TM-induced bEnd.3 cells. Furthermore, the expression of SOD was significantly decreased, while MDA was significantly increased by TM treatment. In contrast, the expression of SOD was dramatically increased, while MDA was remarkably decreased by ESC treatment.

Conclusion: Our results demonstrated that ESC can inhibit ERS/OS and BBB permeability of TM-induced bEnd.3 cells. ESC may alleviate cognitive impairment and prevent comorbidities in MDD patients through ERS/OS.

Sestrin2 suppression aggravates oxidative stress and apoptosis in endothelial cells subjected to pharmacologically induced endoplasmic reticulum stress

Endoplasmic reticulum (ER) stress is an inflammatory response that contributes to endothelial cell dysfunction, a hallmark of cardiovascular diseases, in close interplay with oxidative stress. Recently, Sestrin2 (SESN2) emerged as a novel stress-inducible protein protecting cells from oxidative stress. We investigated here, for the first time, the impact of SESN2 suppression on oxidative stress and cell survival in human endothelial cells subjected to pharmacologically (thapsigargin)-induced ER stress and studied the underlying cellular pathways. We found that SESN2 silencing, though did not specifically induce ER stress, it aggravated the effects of thapsigargin-induced ER stress on oxidative stress and cell survival. This was associated with a dysregulation of Nrf-2, AMPK and mTORC1 signaling pathways. Furthermore, SESN2 silencing aggravated, in an additive manner, apoptosis caused by thapsigargin. Importantly, SESN2 silencing, unlike thapsigargin, caused a dramatic decrease in protein expression and phosphorylation of Akt, a critical pro-survival hub and component of the AMPK/Akt/mTORC1 axis. Our findings suggest that patients with conditions characterized by ER stress activation, such as diabetes, may be at higher risk for cardiovascular complications if their endogenous ability to stimulate and/or maintain expression levels of SESN2 is disturbed or impaired. Therefore, identifying novel or repurposing existing pharmacotherapies to enhance and/or maintain SESN2 expression levels would be beneficial in these conditions.

Down-regulation of AMPK/PPARδ signalling promotes endoplasmic reticulum stress-induced endothelial dysfunction in adult rat offspring exposed to maternal diabetes

AIMS

Exposure to maternal diabetes is associated with increased prevalence of hypertension in the offspring. The mechanisms underlying the prenatal programming of hypertension remain unclear. Because endoplasmic reticulum (ER) stress plays a key role in vascular endothelial dysfunction in hypertension, we investigated whether aberrant ER stress causes endothelial dysfunction and high blood pressure in the offspring of dams with diabetes.

METHODS AND RESULTS

Pregnant Sprague-Dawley rats were intraperitoneally injected with streptozotocin (35 mg/kg) or citrate buffer at Day 0 of gestation. Compared with control mother offspring (CMO), the diabetic mother offspring (DMO) had higher blood pressure and impaired endothelium-dependent relaxation in mesenteric arteries, accompanied by decreased AMPK phosphorylation and PPARδ expression, increased ER stress markers, and reactive oxygen species (ROS) levels. The inhibition of ER stress reversed these aberrant changes in DMO. Ex vivo treatment of mesenteric arteries with an AMPK agonist (A769662) or a PPARδ agonist (GW1516) improved the impaired EDR in DMO and reversed the tunicamycin-induced ER stress, ROS production, and EDR impairment in mesenteric arteries from CMO. The effects of A769662 were abolished by co-treatment with GSK0660 (PPARδ antagonist), whereas the effects of GW1516 were unaffected by Compound C (AMPK inhibitor).

CONCLUSION

These results suggest an abnormal foetal programming of vascular endothelial function in offspring of rats with maternal diabetes that is associated with increased ER stress, which can be ascribed to down-regulation of AMPK/PPARδ signalling cascade.

Oxidative Stress and Vascular Damage in the Context of Obesity: The Hidden Guest

The vascular system plays a central role in the transport of cells, oxygen and nutrients between different regions of the body, depending on the needs, as well as of metabolic waste products for their elimination. While the structure of different components of the vascular system varies, these structures, especially those of main arteries and arterioles, can be affected by the presence of different cardiovascular risk factors, including obesity. This vascular remodeling is mainly characterized by a thickening of the media layer as a consequence of changes in smooth muscle cells or excessive fibrosis accumulation. These vascular changes associated with obesity can trigger functional alterations, with endothelial dysfunction and vascular stiffness being especially common features of obese vessels. These changes can also lead to impaired tissue perfusion that may affect multiple tissues and organs. In this review, we focus on the role played by perivascular adipose tissue, the activation of the renin-angiotensin-aldosterone system and endoplasmic reticulum stress in the vascular dysfunction associated with obesity. In addition, the participation of oxidative stress in this vascular damage, which can be produced in the perivascular adipose tissue as well as in other components of the vascular wall, is updated.

Berberine ameliorates vascular dysfunction by a global modulation of lncRNA and mRNA expression profiles in hypertensive mouse aortae

Objective

The current study investigated the mechanism underlying the therapeutic effects of berberine in the vasculature in hypertension.

Methods

Angiotensin II (Ang II)-loaded osmotic pumps were implanted in C57BL/6J mice with or without berberine administration. Mouse aortae were suspended in myograph for force measurement. Microarray technology were performed to analyze expression profiles of lncRNAs and mRNAs in the aortae. These dysregulated expressions were then validated by qRT-PCR. LncRNA-mRNA co-expression network was constructed to reveal the specific relationships.

Results

Ang Ⅱ resulted in a significant increase in the blood pressure of mice, which was suppressed by berberine. The impaired endothelium-dependent aortic relaxation was restored in hypertensive mice. Microarray data revealed that 578 lncRNAs and 554 mRNAs were up-regulated, while 320 lncRNAs and 377 mRNAs were down-regulated in the aortae by Ang Ⅱ; both were reversed by berberine treatment. qRT-PCR validation results of differentially expressed genes (14 lncRNAs and 6 mRNAs) were completely consistent with the microarray data. GO analysis showed that these verified differentially expressed genes were significantly enriched in terms of “cellular process”, “biological regulation” and “regulation of biological process”, whilst KEGG analysis identified vascular function-related pathways including cAMP signaling pathway, cGMP-PKG signaling pathway, and calcium signaling pathway etc. Importantly, we observed that lncRNA ENSMUST00000144849, ENSMUST00000155383, and AK041185 were majorly expressed in endothelial cells.

Conclusion

The present results suggest that the five lncRNAs ENSMUST00000144849, NR_028422, ENSMUST00000155383, AK041185, and uc.335+ might serve critical regulatory roles in hypertensive vasculature by targeting pivotal mRNAs and subsequently affecting vascular function-related pathways. Moreover, these lncRNAs were modulated by berberine, therefore providing the novel potential therapeutic targets of berberine in hypertension. Furthermore, lncRNA ENSMUST00000144849, ENSMUST00000155383, and AK041185 might be involved in the preservation of vascular endothelial cell function.

NADPH Oxidase 5 Induces Changes in the Unfolded Protein Response in Human Aortic Endothelial Cells and in Endothelial-Specific Knock-in Mice

Oxidative stress constitutes a key molecular mechanism in the development of cardiovascular diseases. A potential relationship between reactive oxygen species (ROS) driven by the NADPH oxidase family (NOX) and the unfolded protein response (UPR) has been postulated. Nevertheless, there is a lack of information about the crosstalk between NOX5 homologue and the UPR in a cardiovascular context. The main aim was to analyze NOX5-mediated ROS effects in the UPR and its importance in cardiovascular diseases. To this effect, we used an adenoviral NOX5-β overexpression model in human aortic endothelial cells (HAEC) and a conditional endothelial NOX5 knock-in mouse. Using expression arrays, we investigated NOX5-induced genomic changes in HAEC. Compared with the control HAEC, 298 genes were differentially expressed. Gene ontology analysis revealed the activation of numerous cellular routes, the most relevant being the UPR pathway. Using real-time PCR and Western Blot experiments, we confirmed that NOX5 overexpression induced changes in the expression of the UPR components, which were associated with increased apoptosis. Moreover, in endothelial-specific NOX5 knock-in mice, we found changes in the expression of the UPR components genes. In these mice, myocardial infarction was performed by permanent coronary artery ligation; however, NOX5 expression was not associated with differences in the UPR components mRNA levels. In these animals, we found significant associations between the UPR components gene expression and echocardiographic parameters. Our data support the idea that NOX5-derived ROS may modulate the UPR pathway in endothelial cells, which might play a relevant role in cardiac physiology.

The involvement of autophagy in the maintenance of endothelial homeostasis: The role of mitochondria

Endothelial mitochondria play important signaling roles critical for the regulation of various cellular processes, including calcium signaling, ROS generation, NO synthesis or inflammatory response. Mitochondrial stress or disturbances in mitochondrial function may participate in the development and/or progression of endothelial dysfunction and could precede vascular diseases. Vascular functions are also strictly regulated by properly functioning degradation machinery, including autophagy and mitophagy, and tightly coordinated by mitochondrial and endoplasmic reticulum responses to stress. Within this review, current knowledge related to the development of cardiovascular disorders and the importance of mitochondria, endoplasmic reticulum and degradation mechanisms in vascular endothelial functions are summarized.

The Anti-atherogenic Role of Exercise Is Associated With the Attenuation of Bone Marrow-Derived Macrophage Activation and Migration in Hypercholesterolemic Mice

An early event in atherogenesis is the recruitment and infiltration of circulating monocytes and macrophage activation in the subendothelial space. Atherosclerosis subsequently progresses as a unresolved inflammatory disease, particularly in hypercholesterolemic conditions. Although physical exercise training has been a widely accepted strategy to inhibit atherosclerosis, its impact on arterial wall inflammation and macrophage phenotype and function has not yet been directly evaluated. Thus, the aim of this study was to investigate the effects of aerobic exercise training on the inflammatory state of atherosclerotic lesions with a focus on macrophages. Hypercholesterolemic LDL-receptor-deficient male mice were subjected to treadmill training for 8 weeks and fed a high-fat diet. Analyses included plasma lipoprotein and cytokine levels; aortic root staining for lipids (oil red O); macrophages (CD68, MCP1 and IL1β); oxidative (nitrotyrosine and, DHE) and endoplasmic reticulum (GADD) stress markers. Primary bone marrow-derived macrophages (BMDM) were assayed for migration activity, motility phenotype (Rac1 and F-actin) and inflammation-related gene expression. Plasma levels of HDL cholesterol were increased, while levels of proinflammatory cytokines (TNFa, IL1b, and IL6) were markedly reduced in the exercised mice. The exercised mice developed lower levels of lipid content and inflammation in atherosclerotic plaques. Additionally, lesions in the exercised mice had lower levels of oxidative and ER stress markers. BMDM isolated from the exercised mice showed a marked reduction in proinflammatory cytokine gene expression and migratory activity and a disrupted motility phenotype. More importantly, bone marrow from exercised mice transplanted into sedentary mice led to reduced atherosclerosis in the recipient sedentary mice, thus suggesting that epigenetic mechanisms are associated with exercise. Collectively, the presented data indicate that exercise training prevents atherosclerosis by inhibiting bone marrow-derived macrophage recruitment and activation.

Endoplasmic reticulum stress and oxidative stress drive endothelial dysfunction induced by high selenium

Selenium is an essential trace element important for human health. A balanced intake is, however, crucial to maximize the health benefits of selenium. At physiological concentrations, selenium mediates antioxidant, anti-inflammatory, and pro-survival actions. However, supra-nutritional selenium intake was associated with increased diabetes risk leading potentially to endothelial dysfunction, the initiating step in atherosclerosis. High selenium causes apoptosis in cancer cells via endoplasmic reticulum (ER) stress, a mechanism also implicated in endothelial dysfunction. Nonetheless, whether ER stress drives selenium-induced endothelial dysfunction, remains unknown. Here, we investigated the effects of increasing concentrations of selenium on endothelial cells. High selenite reduced nitric oxide bioavailability and impaired angiogenesis. High selenite also induced ER stress, increased reactive oxygen species (ROS) production, and apoptosis. Pretreatment with the chemical chaperone, 4-phenylbutyrate, prevented the toxic effects of selenium. Our findings support a model where high selenite leads to endothelial dysfunction through activation of ER stress and increased ROS production. These results highlight the importance of tailoring selenium supplementation to achieve maximal health benefits and suggest that prophylactic use of selenium supplements as antioxidants may entail risk.

Procyanidin B2 mitigates endothelial endoplasmic reticulum stress through a PPARδ-Dependent mechanism

Hyperglycemia-induced endothelial endoplasmic reticulum (ER) stress is implicated in the pathophysiology of diabetes and its vascular complications. Procyanidins are enriched in many plant foods and have been demonstrated to exert several beneficial effects on diabetes, cardiovascular and other metabolic diseases. In the present study, we investigated the effect of procyanidin B2 (PCB2), the most widely distributed natural procyanidin, on ER stress evoked by high glucose in endothelial cells (ECs) and the underlying mechanisms. We showed that PCB2 mitigated the high glucose-activated ER stress pathways (PERK, IRE1α and ATF6) in human vascular ECs. In addition, we found that PCB2 attenuated endothelial ER stress via the activation of peroxisome proliferator-activated receptor δ (PPARδ). We demonstrated that PCB2 directly bound to and activated PPARδ. Conversely, GSK0660, a selective PPARδ antagonist, attenuated the suppressive effect of PCB2 on the ER stress signal pathway. Functionally, PCB2 ameliorated the high glucose-impaired endothelium-dependent relaxation in mouse aortas. The protective effect of PCB2 on vasodilation was abolished in the aortas pretreated with GSK0660 or those from the EC-specific PPARδ knockout mice. Moreover, the protective effects of PCB2 on ER stress and endothelial dysfunction required the inter-dependent actions of PPARδ and AMPK. Collectively, we demonstrated that PCB2 mitigated ER stress and ameliorated vasodilation via a PPARδ-mediated mechanism beyond its classic action as a scavenger of free radicals. These findings further highlighted the novel roles of procyanidins in intervening the ER stress and metabolic disorders related to endothelial dysfunction.

LACC1 Required for NOD2-Induced, ER Stress-Mediated Innate Immune Outcomes in Human Macrophages and LACC1 Risk Variants Modulate These Outcomes

LACC1 genetic variants are associated with multiple immune-mediated diseases. However, laccase domain containing-1 (LACC1) functions are incompletely defined. We find that upon stimulation of the pattern-recognition receptor (PRR) NOD2, LACC1 localizes to the endoplasmic reticulum (ER) and forms a complex with ER-stress sensors. All three ER-stress branches, PERK, IRE1α, and ATF6, are required for NOD2-induced signaling, cytokines, and antimicrobial pathways in human macrophages. LACC1, and its localization to the ER, is required for these outcomes. Relative to wild-type (WT) LACC1, transfection of the common Val254 and rare Arg284 immune-mediated disease-risk LACC1 variants into HeLa cells and macrophages, as well as macrophages from LACC1 Val254 carriers, shows reduced NOD2-induced ER stress-associated outcomes; these downstream outcomes are restored by rescuing ER stress. Therefore, we identify ER stress to be essential in PRR-induced outcomes in macrophages, define a critical role for LACC1 in these ER stress-dependent events, and elucidate how LACC1 disease-risk variants mediate these outcomes.

Gestational Hypoxia Inhibits Pregnancy-Induced Upregulation of Ca2+ Sparks and Spontaneous Transient Outward Currents in Uterine Arteries Via Heightened Endoplasmic Reticulum/Oxidative Stress

Hypoxia during pregnancy profoundly affects uterine vascular adaptation and increases the risk of pregnancy complications, including preeclampsia and fetal intrauterine growth restriction. We recently demonstrated that increases in Ca2+ sparks and spontaneous transient outward currents (STOCs) played an essential role in pregnancy-induced uterine vascular adaptation. In the present study, we hypothesize that gestational hypoxia suppresses Ca2+ sparks/STOCs coupling leading to increased uterine vascular tone via enhanced endoplasmic reticulum (ER)/oxidative stress. Uterine arteries were obtained from nonpregnant and near-term pregnant sheep residing in low altitude or acclimatizing to high-altitude (3801 m) hypoxia for ≈110 days. High-altitude hypoxia suppressed pregnancy-induced upregulation of RyR1 and RyR2 (ryanodine receptor 1 and 2) protein abundance, Ca2+ sparks, and STOCs in uterine arteries. Inhibition of Ca2+ sparks/STOCs with the RyR inhibitor ryanodine significantly increased pressure-dependent myogenic tone in uterine arteries from low-altitude normoxic pregnant animals but not those from high-altitude hypoxic pregnant animals. Gestational hypoxia significantly increased ER/oxidative stress in uterine arteries. Of importance, the hypoxia-mediated suppression of Ca2+ sparks/STOCs and increase in myogenic tone in uterine arteries of pregnant animals were reversed by inhibiting ER/oxidative stress. Of great interest, the impaired sex hormonal regulation of STOCs in high-altitude animals was annulled by scavenging reactive oxygen species but not by inhibiting ER stress. Together, the findings reveal the differential mechanisms of ER and oxidative stresses in suppressing Ca2+ sparks/STOCs and increasing myogenic tone of uterine arteries in hypoxia during gestation, providing new insights into the understanding of pregnancy complications associated with hypoxia.

The microscopic anatomy of endothelial cells in human atherosclerosis: Focus on ER and mitochondria

Once regarded merely as a bland lipid storage disease consequence of aging, atherosclerosis is currently considered a slow and continuous inflammatory process (partially controllable by treatment) with complex etiology involving a multitude of genetic and environmental risk factors which ultimately result in the formation of the plaque. The vascular endothelium, a monolayer of endothelial cells (ECs), is an important regulatory "organ" critical for cardiovascular homeostasis in health which also contributes significantly to the pathomechanisms of several disease states, including atherosclerosis. Over the years, there has been evidence highlighting the central role of endoplasmic reticulum (ER) in the maintenance of endothelial function and perturbations in ER biology have been proposed to adversely affect a diverse range of endothelial functions. Of particular interest is the evidence that under certain pathophysiological circumstances, abnormal ER ultrastructure correlates with altered ER function and signaling and can contribute to cell injury and apoptosis. Therefore, the ultrastructural traits of ER membranes can have important implications not only for their functional bearings but also for the etiology and pathophysiology of diverse human disorders. With regard to atherosclerosis, the focus of ER research has been centered on the molecular signals originated from the ER to manage conditions of stress, leaving the fine structure of this organelle an almost unexplored (but promising) area of studies. There is, also, increasing evidence that mitochondrial dysfunction plays a critical role in promoting cell apoptosis, inflammation, and oxidative stress, thereby contributing to atheroma growth. It is within this context that the present study has been undertaken to investigate the microscopic architecture of ECs in human atherosclerosis and to determine whether the potential structural abnormalities of ER and mitochondria may play a central pathogenic role in atherogenesis or may merely reflect the condition of a tissue whose integrity has already been disturbed or destroyed. For this purpose, transmission electron microscopy (TEM) remains a powerful technique that can not only provide information about the ultrastructural state of cell organelles but also allow the correlation between different subcellular alterations indicative of a certain pathophysiological condition and cellular response. The present study expands the spectrum of ultrastructural defects known to exist in human atherosclerosis and suggests that ER alterations may be of great importance in the pathogenesis of the disease. The architectural changes of ER may be considered early pathological events that precede any overt histologic abnormalities in the vascular endothelium and its subcellular organelles, primarily the mitochondrial pool.

Selective deficiency in endothelial PTP1B protects from diabetes and endoplasmic reticulum stress-associated endothelial dysfunction via preventing endothelial cell apoptosis

Diabetes notably increases the risk for endothelial dysfunction, a main precursor for microvascular complications. While endoplasmic reticulum stress (ERS) and protein tyrosine phosphatase 1B (PTP1B) have been associated with endothelial dysfunction in resistance vessels, whether these mechanisms also contribute to diabetes-mediated endothelial dysfunction in conduit arteries remains unknown. Herein, we tested the hypothesis that diabetes induces macrovascular endothelial dysfunction via endothelial ERS-induced, PTP1B-mediated apoptosis. We showed that diabetes concomitantly increased the expression of PTP1B and of markers of ERS, including GRP78, XBP1, splXBP1 and CHOP in human vessels. Exposure of aortic rings from wild-type mice to the ERS inducers tunicamycin and thapsigargin markedly reduced endothelium-dependent relaxation. Global and endothelial-specific deletion of PTP1B as well as pharmacological inhibition protected aortic rings from ERS-mediated endothelial dysfunction. Nitric oxide synthase inhibition with l-NAME abolished relaxation in the presence and absence of ERS, but neither reactive oxygen species scavenging with tempol or peg-catalase, nor cyclooxygenase inhibition with indomethacin prevented ERS-mediated endothelial dysfunction. However, both p38-MAPK and JNK inhibition protected aortic rings from ERS-mediated endothelial dysfunction. In HUVECs, PTP1B deletion prevented ERS-induced PARP cleavage and apoptosis. Lastly, acute ERS inhibition in aortic rings and selective deficiency of endothelial PTP1B in mice protected mice from diabetes-induced endothelial dysfunction. Altogether, these data support the contribution of the p38/JNK-apoptosis pathway in ERS-mediated endothelial dysfunction and present endothelial PTP1B as a major regulator of endothelial cell viability in conduit vessels and a potential target for the management of macrovascular diseases in diabetes.

A cell permeant phosphopeptide mimetic of Niban inhibits p38 MAPK and restores endothelial function after injury

Vascular injury leads to membrane disruption, ATP release, and endothelial dysfunction. Increases in the phosphorylation of p38 mitogen‐activated protein kinase (p38 MAPK) and decreases in the phosphorylation of Niban, a protein implicated in ER stress and apoptosis, are associated with vascular injury. A cell permeant phosphopeptide mimetic of Niban (NiPp) was generated. The effects of NiPp in restoring endothelial function were determined ex vivo using intact rat aortic tissue (RA) after pharmacological activation of p38 MAPK and also in multiple clinically relevant injury models. Anisomycin (Aniso) increased p38 MAPK phosphorylation and reduced endothelial‐dependent relaxation in RA. Treatment with NiPp prevented Ansio‐induced reduction in endothelial function and increases in p38 MAPK phosphorylation. NiPp treatment also restored endothelial function after stretch injury (subfailure stretch), treatment with acidic Normal Saline (NS), and P2X7R activation with 2′(3′)‐O‐(4‐Benzoylbenzoyl)adenosine 5′‐triphosphate (BzATP). Aged, diseased, human saphenous vein (HSV) remnants obtained from patients undergoing coronary bypass surgical procedures have impaired endothelial function. Treatment of these HSV segments with NiPp improved endothelial‐dependent relaxation. Kinome screening experiments indicated that NiPp inhibits p38 MAPK. These data demonstrate that p38 MAPK and Niban signaling have a role in endothelial function, particularly in response to injury. Niban may represent an endogenous regulator of p38 MAPK activation. The NiPp peptide may serve as an experimental tool to further elucidate p38 MAPK regulation and as a potential therapeutic for endothelial dysfunction.

Tunicamycin induced endoplasmic reticulum changes in endothelial cells investigated in vitro by confocal Raman imaging

This paper describes how tunicamycin (Tu), the most widely used pharmacological agent for inducing endoplasmic reticulum (ER) stress, interacts with endothelial cells. Our results show that tunicamycin enters the cells and accumulates within the ER area. ER stress takes place when improperly folded or damaged proteins begin to accumulate; however, spectroscopic markers of these changes have not been identified as yet. In this work, Raman spectroscopy and scanning electron microscopy imaging of individual endothelial cells treated with Tu were performed. The changes in the biochemical composition of endothelial cells induced by Tu attributed to ER stress were studied in detail. A main feature of the Tu impact on the cells was a decrease of the phospholipid content in the area of ER, and the most abundant lipid with phosphorus groups found there, was identified as sphingomyelin.

Endoplasmic reticulum stress and pulmonary hypertension

Pulmonary hypertension is a fatal disease of which pulmonary vasculopathy is the main pathological feature resulting in the mean pulmonary arterial pressure higher than 25 mmHg. Moreover, pulmonary hypertension remains a tough problem with unclear molecular mechanisms. There have been dozens of studies about endoplasmic reticulum stress during the onset of pulmonary hypertension in patients, suggesting that endoplasmic reticulum stress may have a critical effect on the pathogenesis of pulmonary hypertension. The review aims to summarize the rationale to elucidate the role of endoplasmic reticulum stress in pulmonary hypertension. Started by reviewing the mechanisms responsible for the unfolded protein response following endoplasmic reticulum stress, the potential link between endoplasmic reticulum stress and pulmonary hypertension were introduced, and the contributions of endoplasmic reticulum stress to different vascular cells, mitochondria, and inflammation were described, and finally the potential therapies of attenuating endoplasmic reticulum stress for pulmonary hypertension were discussed.

Chemotherapy Controls Metastasis Through Stimulatory Effects on GRP78 and Its Transcription Factor CREB3L1

To achieve a cure for metastatic breast cancer, further understanding of molecular drivers of the metastatic cascade is essential. Currently, chemotherapy regimens include doxorubicin and paclitaxel which act in part by inducing the unfolded protein response (UPR). The master regulator of the UPR, glucose regulated protein 78 (GRP78), localizes on the surface of tumor cells and is associated with metastatic disease. Cyclic AMP responsive element binding protein 3-like 1 (CREB3L1), a member of the UPR, is a breast cancer metastasis suppressor that acts on cyclic AMP to promote the expression of target genes including GRP78. The aim of the present study was to evaluate the effects of chemotherapy on CREB3L1 and cell-surface GRP78 expression and its association with the development of breast cancer metastasis. For this purpose, we use breast cancer cells migration in vitro assays and an in vivo metastatic mouse model. The results showed that chemotherapy activated CREB3L1 and enhanced cell-surface GRP78 expression specifically in triple-negative breast cancer cells (TNBC), reducing their migration and metastatic potential. CREB3L1 knockout (KO) in the triple negative MDAMB231 cell line using CRISPR/Cas9 technology led to inhibition of GRP78 expression and abrogation of the CREB3L1 metastatic suppression function. Inoculation of CREB3L1-KO MDAMB231 cells into a mouse metastatic model induced a massive metastatic profile which chemotherapy failed to prevent. These findings elucidate a potential pathway to the development of a novel treatment strategy for metastatic TNBC based on modulating CREB3L1 and cell-surface GRP78 expression by chemotherapy and GRP78-targeted drugs.

Rapamycin Rescues Endoplasmic Reticulum Stress-Induced Dry Eye Syndrome in Mice

Purpose

To investigate whether rapamycin protects tear production and the ocular surface during endoplasmic reticulum (ER) stress-induced dry eye syndrome in mice.

Methods

Tunicamycin was injected intraperitoneally in BALB/c mice without or with rapamycin (TM or RM5 group). Peritoneal injection of PBS performed in vehicle group. Group without injection served as control. Blinking rate, fluorescein staining score (FSS), and phenol red thread tear production test were measured at 4 days, 1 week, and 2 weeks after treatment. Levels of inflammatory and angiogenic cytokines were measured by ELISA.

Results

Blinking rate and FSS were elevated, and tear production was decreased in TM group compared with controls (P < 0.05 for all), which was ameliorated by rapamycin at 1 and 2 weeks. Levels of inflammatory and angiogenic cytokines in the cornea and lacrimal glands were higher in the TM group than controls, and lower in the RM5 group than the TM group at 1 and 2 weeks (P < 0.05 for all).

Conclusion

Rapamycin protected tear production and the ocular surface against this dry eye syndrome by ameliorating ER stress-induced vascular damage and inflammation of lacrimal glands and the ocular surface.

Enhanced endoplasmic reticulum and mitochondrial stress in abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is a degenerative vascular disease with a complex aetiology that remains to be fully elucidated. Clinical management of AAA is limited to surgical repair, while an effective pharmacotherapy is still awaited. Endoplasmic reticulum (ER) stress and mitochondrial dysfunction have been involved in the pathogenesis of cardiovascular diseases (CVDs), although their contribution to AAA development is uncertain. Therefore, we aimed to determine their implication in AAA and investigated the profile of oxysterols in plasma, specifically 7-ketocholesterol (7-KC), as an ER stress inducer.In the present study, we determined aortic ER stress activation in a large cohort of AAA patients compared with healthy donors. Higher gene expression of activating transcription factor (ATF) 6 (ATF6), IRE-1, X-binding protein 1 (XBP-1), C/EBP-homologous protein (CHOP), CRELD2 and suppressor/enhancer of Lin-12-like (SEL1L) and greater protein levels of active ATF6, active XBP1 and of the pro-apoptotic protein CHOP were detected in human aneurysmatic samples. This was accompanied by an exacerbated apoptosis, higher reactive oxygen species (ROS) production and by a reduction in mitochondrial biogenesis in the vascular wall of AAA. The quantification of oxysterols, performed by liquid chromatography-(atmospheric pressure chemical ionization (APCI))-mass spectrometry, showed that levels of 7-KC were significantly higher while those of 7α-hydroxycholesterol (HC), 24-HC and 27-HC were lower in AAA patients compared with healthy donors. Interestingly, the levels of 7-KC correlate with the expression of ER stress markers.Our results evidence an induction of ER stress in the vascular wall of AAA patients associated with an increase in circulating 7-KC levels and a reduction in mitochondrial biogenesis suggesting their implication in the pathophysiology of this disease.

Endoplasmic Reticulum Stress: A Critical Molecular Driver of Endothelial Dysfunction and Cardiovascular Disturbances Associated with Diabetes

Physical inactivity and sedentary lifestyle contribute to the widespread epidemic of obesity among both adults and children leading to rising cases of diabetes. Cardiovascular disease complications associated with obesity and diabetes are closely linked to insulin resistance and its complex implications on vascular cells particularly endothelial cells. Endoplasmic reticulum (ER) stress is activated following disruption in post-translational protein folding and maturation within the ER in metabolic conditions characterized by heavy demand on protein synthesis, such as obesity and diabetes. ER stress has gained much interest as a key bridging and converging molecular link between insulin resistance, oxidative stress, and endothelial cell dysfunction and, hence, represents an interesting drug target for diabetes and its cardiovascular complications. We reviewed here the role of ER stress in endothelial cell dysfunction, the primary step in the onset of atherosclerosis and cardiovascular disease. We specifically focused on the contribution of oxidative stress, insulin resistance, endothelial cell death, and cellular inflammation caused by ER stress in endothelial cell dysfunction and the process of atherogenesis.

Mast Cells Induce Blood Brain Barrier Damage in SCD by Causing Endoplasmic Reticulum Stress in the Endothelium

Endothelial dysfunction underlies the pathobiology of cerebrovascular disease. Mast cells are located in close proximity to the vasculature, and vasoactive mediators released upon their activation can promote endothelial activation leading to blood brain barrier (BBB) dysfunction. We examined the mechanism of mast cell-induced endothelial activation via endoplasmic reticulum (ER) stress mediated P-selectin expression in a transgenic mouse model of sickle cell disease (SCD), which shows BBB dysfunction. We used mouse brain endothelial cells (mBECs) and mast cells-derived from skin of control and sickle mice to examine the mechanisms involved. Compared to control mouse mast cell conditioned medium (MCCM), mBECs incubated with sickle mouse MCCM showed increased, structural disorganization and swelling of the ER and Golgi, aggregation of ribosomes, ER stress marker proteins, accumulation of galactose-1-phosphate uridyl transferase, mitochondrial dysfunction, reactive oxygen species (ROS) production, P-selectin expression and mBEC permeability. These effects of sickle-MCCM on mBEC were inhibited by Salubrinal, a reducer of ER stress. Histamine levels in the plasma, skin releasate and in mast cells of sickle mice were higher compared to control mice. Compared to control BBB permeability was increased in sickle mice. Treatment of mice with imatinib, Salubrinal, or P-selectin blocking antibody reduced BBB permeability in sickle mice. Mast cells induce endothelial dysfunction via ER stress-mediated P-selectin expression. Mast cell activation contributes to ER stress mediated endothelial P-selectin expression leading to increased endothelial permeability and impairment of BBB. Targeting mast cells and/or ER stress has the potential to ameliorate endothelial dysfunction in SCD and other pathobiologies.

Crosstalk Between Oxidative Stress and Endoplasmic Reticulum (ER) Stress in Endothelial Dysfunction and Aberrant Angiogenesis Associated With Diabetes: A Focus on the Protective Roles of Heme Oxygenase (HO)-1

Type-2 diabetes prevalence is continuing to rise worldwide due to physical inactivity and obesity epidemic. Diabetes and fluctuations of blood sugar are related to multiple micro- and macrovascular complications, that are attributed to oxidative stress, endoplasmic reticulum (ER) activation and inflammatory processes, which lead to endothelial dysfunction characterized, among other features, by reduced availability of nitric oxide (NO) and aberrant angiogenic capacity. Several enzymatic anti-oxidant and anti-inflammatory agents have been found to play protective roles against oxidative stress and its downstream signaling pathways. Of particular interest, heme oxygenase (HO) isoforms, specifically HO-1, have attracted much attention as major cytoprotective players in conditions associated with inflammation and oxidative stress. HO operates as a key rate-limiting enzyme in the process of degradation of the iron-containing molecule, heme, yielding the following byproducts: carbon monoxide (CO), iron, and biliverdin. Because HO-1 induction was linked to pro-oxidant states, it has been regarded as a marker of oxidative stress; however, accumulating evidence has established multiple cytoprotective roles of the enzyme in metabolic and cardiovascular disorders. The cytoprotective effects of HO-1 depend on several cellular mechanisms including the generation of bilirubin, an anti-oxidant molecule, from the degradation of heme; the induction of ferritin, a strong chelator of free iron; and the release of CO, that displays multiple anti-inflammatory and anti-apoptotic actions. The current review article describes the major molecular mechanisms contributing to endothelial dysfunction and altered angiogenesis in diabetes with a special focus on the interplay between oxidative stress and ER stress response. The review summarizes the key cytoprotective roles of HO-1 against hyperglycemia-induced endothelial dysfunction and aberrant angiogenesis and discusses the major underlying cellular mechanisms associated with its protective effects.

Single-dose radiotherapy disables tumor cell homologous recombination via ischemia/reperfusion injury

Tumor cure with conventional fractionated radiotherapy is 65%, dependent on tumor cell-autonomous gradual buildup of DNA double-strand break (DSB) misrepair. Here we report that single-dose radiotherapy (SDRT), a disruptive technique that ablates more than 90% of human cancers, operates a distinct dual-target mechanism, linking acid sphingomyelinase-mediated (ASMase-mediated) microvascular perfusion defects to DNA unrepair in tumor cells to confer tumor cell lethality. ASMase-mediated microcirculatory vasoconstriction after SDRT conferred an ischemic stress response within parenchymal tumor cells, with ROS triggering the evolutionarily conserved SUMO stress response, specifically depleting chromatin-associated free SUMO3. Whereas SUMO3, but not SUMO2, was indispensable for homology-directed repair (HDR) of DSBs, HDR loss of function after SDRT yielded DSB unrepair, chromosomal aberrations, and tumor clonogen demise. Vasoconstriction blockade with the endothelin-1 inhibitor BQ-123, or ROS scavenging after SDRT using peroxiredoxin-6 overexpression or the SOD mimetic tempol, prevented chromatin SUMO3 depletion, HDR loss of function, and SDRT tumor ablation. We also provide evidence of mouse-to-human translation of this biology in a randomized clinical trial, showing that 24 Gy SDRT, but not 3×9 Gy fractionation, coupled early tumor ischemia/reperfusion to human cancer ablation. The SDRT biology provides opportunities for mechanism-based selective tumor radiosensitization via accessing of SDRT/ASMase signaling, as current studies indicate that this pathway is tractable to pharmacologic intervention.

Inhibition of endoplasmic reticulum stress protected DOCA-salt hypertension-induced vascular dysfunction

Hypertension has complex vascular pathogenesis and therefore the molecular etiology remains poorly elucidated. Endoplasmic reticulum stress (ERS), which is a condition of the unfolded/misfolded protein accumulation in the endoplasmic reticulum, has been defined as a potential target for cardiovascular disease. In the present study, the effects of ERS inhibition on hypertension-induced alterations in the vessels were investigated. In male Wistar albino rats, hypertension was induced through unilateral nephrectomy, deoxycorticosterone-acetate (DOCA) injection (20 mg/kg, twice a week) and 1% NaCl with 0.2% KCI added to drinking water for 12 weeks. An ERS inhibitor, tauroursodeoxycolic acid (TUDCA) (150 mg/kg/day, i.p.), was administered for the final four weeks. ERS inhibition in DOCA-salt induced hypertension was observed to have reduced systolic blood pressure, improved endothelial dysfunction, enhanced plasma nitric oxide (NO) level, reduced protein expressions of phosphorylated-double-stranded RNA-activated protein kinase-like endoplasmic reticulum kinase (pPERK), 78 kDa glucose-regulated protein (GRP78), Inositol trisphosphate receptor1 (IP₃R1) and Epidermal growth factor receptor (EGFR), increased expressions of endoplasmic reticulum Ca²⁺-ATPase2 (SERCA2) and B cell lymphoma2 (Bcl2) in vessels. These findings suggest that the beneficial effects of ERS inhibition on hypertension may be related to protection of vessel functions through restoration of endoplasmic reticulum calcium homeostasis, and apoptotic and mitotic pathways.

Micromanaging human placental function: differential microRNA expression in feto-placental endothelial cells of gestational diabetes pregnancies

Healthy development in utero relies on the appropriate exchange of nutrients and other signalling between the maternal and fetal circulations. Disruption to this fine balance is associated with several pregnancy and adverse birth outcomes, including gestational diabetes mellitus (GDM). This is a complex condition influenced by genetic, environment and potentially epigenetic factors in association with a range of altered developmental outcomes. A recent study, published in Clinical Science, explores miRNAs as a molecular mechanism underpinning the altered function of placental endothelial cells in GDM pregnancies.

Cross Talk Between p22phox and ATF4 in the Endothelial Unfolded Protein Response

BACKGROUND

Cardiovascular diseases have been associated with stress in the endoplasmic reticulum (ER) and accumulation of unfolded proteins leading to the unfolded protein response (UPR). Reactive oxygen species (ROS) such as superoxide and H₂O₂ derived from NADPH oxidases have been implicated in the pathogenesis of cardiovascular diseases. ROS have also been associated with ER stress. The role NADPH oxidases in the UPR is, however, not completely resolved yet.

AIM

In this study, we investigated the role of p22phox, an essential component of most NADPH oxidases, in the UPR of endothelial cells.

RESULTS

Induction of ER stress increased p22phox expression at the transcriptional level. p22phox was identified as novel target of the UPR transcription factor ATF4 (activator of transcription factor 4) under ER stress conditions by promoter analyses and ChIP. Depletion of ATF4 and p22phox diminished the levels of superoxide and H₂O₂ under ER stress conditions. On the contrary, p22phox was instrumental in increasing eIF2α phosphorylation and subsequent ATF4 expression on induction of ER stress by chemicals, oxysterols, or severe hypoxia in vitro and in vivo, leading to increased expression of CHOP and activation of effector caspases.

INNOVATION

p22phox is a novel target of ATF4 in response to ER stress, which can promote the PERK-ATF4 branch of the UPR in vitro and in vivo.

CONCLUSION

p22phox-dependent NADPH oxidases are important mediators of ER stress driving the UPR.

TGF-β downregulation-induced cancer cell death is finely regulated by the SAPK signaling cascade

Transforming growth factor (TGF)-β signaling is increasingly recognized as a key driver in cancer. In progressive cancer tissues, TGF-β promotes tumor formation, and its increased expression often correlates with cancer malignancy. In this study, we utilized adenoviruses expressing short hairpin RNAs against TGF-β1 and TGF-β2 to investigate the role of TGF-β downregulation in cancer cell death. We found that the downregulation of TGF-β increased the phosphorylation of several SAPKs, such as p38 and JNK. Moreover, reactive oxygen species (ROS) production was also increased by TGF-β downregulation, which triggered Akt inactivation and NOX4 increase-derived ROS in a cancer cell-type-specific manner. We also revealed the possibility of substantial gene fluctuation in response to TGF-β downregulation related to SAPKs. The expression levels of Trx and GSTM1, which encode inhibitory proteins that bind to ASK1, were reduced, likely a result of the altered translocation of Smad complex proteins rather than from ROS production. Instead, both ROS and ROS-mediated ER stress were responsible for the decrease in interactions between ASK1 and Trx or GSTM1. Through these pathways, ASK1 was activated and induced cytotoxic tumor cell death via p38/JNK activation and (or) induction of ER stress.

Reducing the levels of the multifunctional protein transforming growth factor (TGF)-β in cancer cells prevents tumor growth in mice. Previous studies have shown that high levels of TGF-β in cancerous tissue are associated with accelerated disease progression. Hye Jin Choi and Jae J Song at Yonsei University in Seoul, South Korea, and colleagues infected cancer cells with genetically modified viruses that reduced the expression of the gene encoding TGF-β. The resulting decrease in TGF-β protein led to cell death by stimulating the production of reactive oxygen species and signaling through the apoptosis signal-regulating kinase 1 (ASK1) pathway. When tumor-bearing mice were infected with these modified viruses, their overall survival was improved. Further understanding the mechanisms through which TGF-β regulates cancer cell survival will contribute to the development of new approaches in cancer treatment.