Modulating ER Stress Research Articles

α-ketoglutarate ameliorates colitis through modulation of inflammation, ER stress, and apoptosis.

Colitis is an inflammatory disorder of the gastrointestinal tract. A widely consumed dietary nutrient, α-ketoglutarate (α-KG) is known to play a crucial role in cellular metabolism and provide protection to intestinal epithelium under various pathophysiological conditions. In this study, 2,4,6-trinitrobenzenesulfonic acid (TNBS) was used to induce colitis in Wistar rats. After 36 hours of TNBS administration, the rats were orally treated with a solution of α-KG at 1 g/kg body weight for 5 days. Development of colitis was confirmed by observable physical symptoms of repeated loose blood-mixed stool, apathy for food and weight loss. Macroscopic inspection revealed an inflamed colonic surface with ulcerations. Histopathological observations included alterations in crypts-structure and disruption in both epithelial and mucosal layers of colon in colitis induced rats. Colitis resulted in elevated levels of pro-inflammatory cytokines, ER stress-mediated cell death and intrinsic apoptosis pathway. The ameliorative effects of α-KG against TNBS-mediated toxicity were confirmed through molecular technics and docking analysis. Additionally, there were no instances of toxicity of α-KG. Therefore, α-KG can be considered as a valuable therapeutic agent for further comprehensive research.

Triptolide induces immunogenic cell death in cervical cancer cells via ER stress and redox modulation

Triptolide induces immunogenic cell death in cervical cancer cells via ER stress and redox modulation

LPCAT1 reduces inflammatory response, apoptosis and barrier damage of nasal mucosal epithelial cells caused by allergic rhinitis through endoplasmic reticulum stress.

Allergic rhinitis (AR), common in children and adolescents, involves Lysophosphatidylcholine acyltransferase 1 (LPCAT1) catalyzing surfactant lipid biosynthesis and suppressing endoplasmic reticulum expression. However, the precise mechanism underlying the impact of LPCAT1 on epithelial cell damage in AR remains elusive. Hence, the present investigation elucidated the potential effect of LPCAT1 on epithelial cell damage in AR by inhibiting endoplasmic reticulum stress. To assess cell viability, CCK8 assay was employed. Additionally, western blotting was utilized to evaluate the expression of endoplasmic reticulum stress-associated proteins ATF6, CHOP, p-eIF2α, p-IRE1, and LPCAT1. Subsequently, an interference plasmid targeting LPCAT1 was constructed, and western blot analysis was conducted to determine interference level of LPCAT1. An ELISA assay was employed to quantify the concentrations of TNFα, IL-1β, IL-6, GM-CSF, and eotaxin. Additionally, flow cytometry and western blotting techniques were utilized to evaluate cellular apoptosis, whereas immunofluorescence staining was applied to detect the expression levels of ZO-1. Our findings indicated that IL-13 stimulation resulted in an elevated expression of ER stress proteins and LPCAT1 in nasal mucosal epithelial cells. Furthermore, LPCAT1 interference diminished the expression of inflammatory mediators, apoptosis markers, barrier disruption indicators, and ER stress proteins in IL-13-stimulated nasal mucosal epithelial cells. Further, by inhibiting ER stress, LPCAT1 interference diminished the expression of inflammatory factors, apoptosis, and barrier damage in nasal mucosal epithelial cells stimulated by IL-13. Concisely, LPCAT1 ameliorates AR-induced inflammation, apoptosis, and barrier impairment in nasal mucosal epithelial cells by modulating ER stress, implying its potential as a novel therapeutic target for AR.

Herbo-vitamin medicine Livogrit Vital ameliorates isoniazid induced liver injury (IILI) in human liver (HepG2) cells by decreasing isoniazid accumulation and oxidative stress driven hepatotoxicity

BackgroundTuberculosis (TB) is a leading cause of infection related mortality. Isoniazid is one of the frontline drugs for anti-TB therapy. Hepatotoxicity induced by isoniazid is a major cause of drug-discontinuation which may lead to development of resistant TB or increased mortality.PurposeTo characterize pharmacological properties of plant-based prescription medicine, Livogrit Vital (LVV) against isoniazid-induced liver injury (IILI) using HepG2 cells.MethodPhytometabolite characterization of LVV was performed by High-performance liquid chromatography (HPLC). The effects of LVV on cytosafety, IC50 shift, oxidative stress, ER stress, apoptosis, liver injury markers, and accumulation of isoniazid and hydrazine was performed on HepG2 cells induced with isoniazid. Silymarin was used as the positive control.ResultsHPLC based phytometabolite characterization of LVV revealed the presence of several anti-oxidant, anti-apoptotic, and hepatoprotective compounds. In isoniazid-induced HepG2 cells, LVV reduced cytotoxicity of isoniazid and shifted its IC50 value. Treatment with LVV reduced ROS generation and lipid peroxidation; enhanced GSH enzyme levels in isoniazid-induced HepG2 cells. As per the mechanistic evaluation, LVV modulated gene expression level of Caspase-3, FGF21, and IRE-1α. LVV treatment also normalized isoniazid-induced elevated Caspase-3 activity and cPARP1 protein levels, indicating its potentials to regulate liver cell apoptosis. Concomitantly, biomarkers of hepatotoxicity, ALT and GGT, also decreased by LVV treatment. Interestingly, LVV treatment reduced intracellular accumulation of isoniazid and its toxic metabolite hydrazine, in isoniazid-stimulated HepG2 cells.ConclusionTreatment of hepatic cells with the herbo-vitamin medicine, Livogrit Vital, regulates IILI by modulation of oxidative and ER stress, apoptosis, and bioaccumulation of isoniazid and hydrazine. Collectively, Livogrit Vital could well be explored as an adjuvant hepatoprotective agent alongwith anti-TB medicines.

MiR-421-mediated suppression of FGF13 as a novel mechanism ameliorates cardiac hypertrophy by inhibiting endoplasmic reticulum stress

Pathological cardiac hypertrophy is an independent risk factor for heart failure. Currently, clinical treatments offer limited effectiveness, and both mortality and morbidity from cardiac hypertrophy and heart failure continue to be significant. Therefore, it is extremely urgent to find new intervention targets to prevent and alleviate pathological cardiac hypertrophy. In this study, we explored FGF13 expression and its upstream regulators in hypertrophic hearts. Firstly, we observed an increase in FGF13 expression levels in human hypertrophic myocardium tissues, as well as in mouse models of TAC-induced hypertrophy and in neonatal rat cardiomyocyte (NRCM) models induced by isoproterenol (ISO). Moreover, these elevated levels of FGF13 were shown to positively correlate with hypertrophic markers, including ANP and BNP. By using both gain-of-function and loss-of-function approaches in an in vitro hypertrophy model, we demonstrated that FGF13 knockdown could inhibit endoplasmic reticulum stress (ERS), thereby ameliorating cardiomyocyte hypertrophy. Meanwhile, we investigated the upstream regulators of FGF13 in hypertrophic hearts, and a dual-luciferase reporter assay confirmed that FGF13 is a direct target of miR-421. Overexpression of miR-421 decreased the protein level of FGF13 and ameliorated ISO-induced cardiomyocyte hypertrophy via modulating ER stress. In contrast, overexpression of FGF13 attenuated the ameliorative effect of miR-421 on ISO-induced cardiomyocyte hypertrophy. Taken together, the present results suggested that miR-421 ameliorated ISO-induced cardiomyocyte hypertrophy by negatively regulating FGF13 expression. This finding may offer a novel approach for the treatment of cardiac hypertrophy.

Metabolism of primary high-grade serous ovarian carcinoma (HGSOC) cells under limited glutamine or glucose availability

BackgroundHigh-grade serous ovarian carcinoma (HGSOC) is the most common and aggressive subtype of epithelial ovarian carcinoma. It is primarily diagnosed at stage III or IV when the 5-year survival rate ranges between 20% and 40%. Here, we aimed to validate the hypothesis, based on HGSOC cell lines, that proposed the existence of two distinct groups of HGSOC cells with high and low oxidative phosphorylation (OXPHOS) metabolism, respectively, which are associated with their responses to glucose and glutamine withdrawal.MethodsWe isolated and cultivated primary cancer cell cultures from HGSOC and nontransformed ovarian fibroblasts from the surrounding ovarium of 45 HGSOC patients. We tested the metabolic flexibility of the primary cells, particularly in response to glucose and glutamine depletion, analyzed and modulated endoplasmic reticulum stress, and searched for indices of the existence of previously reported groups of HGSOC cells with high and low OXPHOS metabolism.ResultsThe primary HGSOC cells did not form two groups with high and low OXPHOS that responded differently to glucose and glutamine availabilities in the cell culture medium. Instead, they exhibited a continuum of OXPHOS phenotypes. In most tumor cell isolates, the responses to glucose or glutamine withdrawal were mild and surprisingly correlated with those of nontransformed ovarian fibroblasts from the same patients. The growth of tumor-derived cells in the absence of glucose was positively correlated with the lipid trafficking regulator FABP4 and was negatively correlated with the expression levels of HK2 and HK1. The correlations between the expression of electron transport chain (ETC) proteins and the oxygen consumption rates or extracellular acidification rates were weak. ER stress markers were strongly expressed in all the analyzed tumors. ER stress was further potentiated by tunicamycin but not by the recently proposed ER stress inducers based on copper(II)-phenanthroline complexes. ER stress modulation increased autophagy in tumor cell isolates but not in nontransformed ovarian fibroblasts.ConclusionsAnalysis of the metabolism of primary HGSOC cells rejects the previously proposed hypothesis that there are distinct groups of HGSOC cells with high and low OXPHOS metabolism that respond differently to glutamine or glucose withdrawal and are characterized by ETC protein levels.

Cardiovascular protection of YiyiFuzi powder and the potential mechanisms through modulating mitochondria-endoplasmic reticulum interactions.

Cardiovascular diseases (CVD) remain the leading cause of death worldwide and represent a major public health challenge. YiyiFuzi Powder (YYFZ), composed of Coicis semen and Fuzi, is a classical traditional Chinese medicine prescription from the Synopsis of Golden Chamber dating back to the Han Dynasty. Historically, YYFZ has been used to treat various CVD, rooted in Chinese therapeutic principles. Network pharmacology analysis indicated that YYFZ may exhibit direct or indirect effects on mitochondria-endoplasmic reticulum (ER) interactions. This review, focusing on the cardiovascular protective effects of Coicis semen and Fuzi, summarizes the potential mechanisms by which YYFZ acts on mitochondria and the ER. The underlying mechanisms are associated with regulating cardiovascular risk factors (such as blood lipids and glucose), impacting mitochondrial structure and function, modulating ER stress, inhibiting oxidative stress, suppressing inflammatory responses, regulating cellular apoptosis, and maintaining calcium ion balance. The involved pathways include, but were not limited to, upregulating the IGF-1/PI3K/AKT, cAMP/PKA, eNOS/NO/cGMP/SIRT1, SIRT1/PGC-1α, Klotho/SIRT1, OXPHOS/ATP, PPARα/PGC-1α/SIRT3, AMPK/JNK, PTEN/PI3K/AKT, β2-AR/PI3K/AKT, and modified Q cycle signaling pathways. Meanwhile, the MCU, NF-κB, and JAK/STAT signaling pathways were downregulated. The PERK/eIF2α/ATF4/CHOP, PERK/SREBP-1c/FAS, IRE1, PINK1-dependent mitophagy, and AMPK/mTOR signaling pathways were bidirectionally regulated. High-quality experimental studies are needed to further elucidate the underlying mechanisms of YYFZ in CVD treatment.

Exploring the Role of Endoplasmic Reticulum Stress in Various Diseases: Implications and Potential Therapeutic Strategies

This study examines prospective therapeutic approaches to modulate Endoplasmic reticulum stress (ER stress) for disease intervention and emphasizes the significant role of ER stress in the pathophysiology of numerous diseases. ER stress is an intracellular stress response when the ER fails to properly fold and repair proteins. This cellular stress response holds crucial relevance in developing many diseases, such as metabolic-related diseases, neurodegenerative diseases, and cardiovascular diseases. This work reviews the underlying mechanisms of ER stress and summarizes its association with various diseases. ER stress can lead to the disordered accumulation of intracellular proteins and the abnormality of cell function, impairing the normal physiological function of cells. These abnormal processes are closely related to disease development.Furthermore, several potential therapeutic options have been described, aiming to modulate ER stress and alleviate symptoms of associated diseases. These therapeutic options include small molecules, chemical chaperones, modulation of the UPR signaling pathway, gene therapy, and more. By modulating ER stress, researchers can intervene in disease development and provide new ideas and methods for preventing and treating these diseases.

Targeting PAK4 reverses cisplatin resistance in NSCLC by modulating ER stress

Chemoresistance poses a significant impediment to effective treatments for non-small-cell lung cancer (NSCLC). P21-activated kinase 4 (PAK4) has been implicated in NSCLC progression by invasion and migration. However, the involvement of PAK4 in cisplatin resistance is not clear. Here, we presented a comprehensive investigation into the involvement of PAK4 in cisplatin resistance within NSCLC. Our study revealed enhanced PAK4 expression in both cisplatin-resistant NSCLC tumors and cell lines. Notably, PAK4 silencing led to a remarkable enhancement in the chemosensitivity of cisplatin-resistant NSCLC cells. Cisplatin evoked endoplasmic reticulum stress in NSCLC. Furthermore, inhibition of PAK4 demonstrated the potential to sensitize resistant tumor cells through modulating endoplasmic reticulum stress. Mechanistically, we unveiled that the suppression of the MEK1-GRP78 signaling pathway results in the sensitization of NSCLC cells to cisplatin after PAK4 knockdown. Our findings establish PAK4 as a promising therapeutic target for addressing chemoresistance in NSCLC, potentially opening new avenues for enhancing treatment efficacy and patient outcomes.

Inhibiting the endoplasmic reticulum stress response enhances the effect of doxorubicin by altering the lipid metabolism of liver cancer cells

Hepatocellular carcinoma (HCC) is characterized by a low and variable response to chemotherapeutic treatments. One contributing factor to the overall pharmacodynamics is the activation of endoplasmic reticulum (ER) stress pathways. This is a cellular stress mechanism that becomes activated when the cell's need for protein synthesis surpasses the ER's capacity to maintain accurate protein folding, and has been implicated in creating drug-resistance in several solid tumors. ObjectiveTo identify the role of ER-stress and lipid metabolism in mediating drug response in HCC. MethodsBy using a chemically-induced mouse model for HCC, we administered the ER-stress inhibitor 4μ8C and/or doxorubicin (DOX) twice weekly for three weeks post-tumor initiation. Histological analyses were performed alongside comprehensive molecular biology and lipidomics assessments of isolated liver samples. In vitro models, including HCC cells, spheroids, and patient-derived liver organoids were subjected to 4μ8C and/or DOX, enabling us to assess their synergistic effects on cellular viability, lipid metabolism, and oxygen consumption rate. ResultsWe reveal a pivotal synergy between ER-stress modulation and drug response in HCC. The inhibition of ER-stress using 4μ8C not only enhances the cytotoxic effect of DOX, but also significantly reduces cellular lipid metabolism. This intricate interplay culminates in the deprivation of energy reserves essential for the sustenance of tumor cells. ConclusionsThis study elucidates the interplay between lipid metabolism and ER-stress modulation in enhancing doxorubicin efficacy in HCC. This novel approach not only deepens our understanding of the disease, but also uncovers a promising avenue for therapeutic innovation. The long-term impact of our study could open the possibility of ER-stress inhibitors and/or lipase inhibitors as adjuvant treatments for HCC-patients.

NTRK1-mediated protection against manganese-induced neurotoxicity and cell apoptosis via IGF2 in SH-SY5Y cells

BackgroundExcessive manganese (Mn) exposure has been linked to neurotoxicity, cognitive impairments. Neurotrophic Receptor Kinase 1 (NTRK1) encodes Tropomyosin kinase A (TrkA), a neurotrophic receptor, as a mediator of neuron differentiation and survival. Insulin-like growth factor 2 (IGF2), a pivotal member of the insulin gene family, plays a crucial role in brain development and neuroprotection. Despite this knowledge, the precise mechanisms through which NTRK1 and IGF2 influence cell responses to Mn-induced neuronal damage remain elusive. MethodsCell apoptosis was assessed using CCK8, TUNEL staining, and Western blot analysis of cleaved Caspase-3. Lentiviral vectors facilitated NTRK1 overexpression, while small interfering RNAs (siRNAs) facilitated IGF2 knockdown. Real-time Quantitative PCR (qPCR) determined gene expression levels, while Western blotting measured protein expression. ResultsThe study reveals that NTRK1 inhibits MnCl2-induced apoptosis in SH-SY5Y cells. NTRK1 overexpression significantly upregulated IGF2 expression, and subsequent siRNA-IGF2 experiments confirmed IGF2's pivotal role in NTRK1-mediated neuroprotection. Notably, the study identifies that NTRK1 regulates the expression of IGF2 in the neuroprotective mechanism with the involvement of ER stress pathways. DiscussionThe study reveals NTRK1's neuroprotective role via IGF2 against Mn-induced neurotoxicity and ER stress modulation in SH-SY5Y cells. These findings offer insights into potential therapies for neurodegenerative disorders related to Mn exposure and NTRK1 dysfunction, driving future research in this domain.

Abstract 17307: Pre-Existing Endoplasmic Reticulum (ER) Stress Inhibits Sars-Co-V2 Entry Into Host Cells Through Modulation of AKT Signaling and Unfolded Protein Response (UPR)

Introduction: It is well known that SARS-Co-V2 infection can induce ER stress-associated activation of unfolded protein response (UPR) in various host cells which may contribute to the pathogenesis of COVID-19. However, the interplay between SARS-Co-V2 infection and UPR signaling in pre-existing ER stress associated pathological conditions has not been well elucidated. Hypothesis: We hypothesized that modulation of a pre-existing ER stress in host cells could attenuate susceptibility to SARS-CoV-2 infection by activating a range of cellular defense. Methods: Increasing concentrations of Tunicamycin (Tm) and Thapsigargin (Tg) have been used to induce ER stress in Huh-7 cells. After 6h treatment, cells were infected with SARS-CoV-2 pseudotyped particles (SARS-CoV-2pp) for 48 p.i. SARS-Co-V2-2pp entry was measured using Bright Glo TM luciferase assay. Cell viability was measured by cell titer Glo ® luminescent cell viability assay. The mRNA and protein expression of UPR markers were evaluated using RT-qPCR and Western blot methods. Results: Tm (5 μg/ml) and Tg (1 μM) efficiently inhibited SARS-CoV-2pp entry into cells without any cytotoxic effect. Chemical ER stress-induced inhibition of SARS-CoV-2pp entry was associated with significant reduction of ACE2 expression in Tg-infected cells but not with Tm. Strikingly, Tm and Tg revealed differential effects in modulating the expression of ER stress genes in infected cells. Both Tm and Tg significantly reduced the expression of stress-inducible ER chaperone GRP78/BIP in infected cells. In contrast, the IRE1-XBP1s and PERK-eIF2α-ATF4-CHOP signaling pathways were downregulated in Tg-infected cells only. Additionally, insulin-mediated glucose uptake, phosphorylation of Ser 307 IRS-1 and downstream p-AKT were enhanced in Tg-infected cells without any change in ERK phosphorylation. Conclusions: These findings suggest that pre-existing ER stress could modulate a specific UPR response in infected cells capable of counteracting the stress-inducible elements signaling, thereby depriving SARS-Co-V2 of essential components for their entry and replication. Pharmacological manipulation of ER stress in host cells might provide new therapeutic strategies to alleviate SARS-CoV-2 infection.

Caffeic acid's role in mitigating polycystic ovary syndrome by countering apoptosis and ER stress triggered by oxidative stress

Polycystic ovary syndrome (PCOS) is a complex endocrine disorder that affects women of reproductive age, characterized by androgen-induced oxidative stress leading to several metabolic disorders. In this study, we investigated the potential therapeutic effect of caffeic acid on PCOS and its underlying molecular mechanism. We used a human ovarian granulosa cell line (KGN cells) induced by hydrogen peroxide (H2O2) to examine how caffeic acid influences the protein expression of oxidative stress-induced apoptosis-related markers. Our results indicate that caffeic acid significantly inhibits intracellular reactive oxygen species (ROS) generation and safeguards KGN cells against oxidative stress. For the in vivo aspect of our study, female Sprague-Dawley (SD) rats were utilized to induce the PCOS model using dehydroepiandrosterone (DHEA). Caffeic acid was then administered to the rats for a duration of 6 weeks. The outcomes revealed that caffeic acid effectively improved irregular estrous cycles, fasting blood glucose levels, liver function, and lipid profiles in DHEA-induced PCOS rats. Additionally, it mitigated hyperandrogenism, enhanced steroidogenesis enzyme expression, and modulated apoptosis-related protein expression. Our findings strongly suggest that caffeic acid holds promising potential in reducing oxidative stress-induced damage and ameliorating PCOS-related complications by modulating ER stress.

Melatonin Engineering M2 Macrophage-Derived Exosomes Mediate Endoplasmic Reticulum Stress and Immune Reprogramming for Periodontitis Therapy.

Periodontitis is a chronic infectious disease caused by bacterial irritation. As an essential component of the host immunity, macrophages are highly plastic and play a crucial role in inflammatory response. An appropriate and timely transition from proinflammatory (M1) to anti-inflammatory (M2) macrophages is indispensable for treating periodontitis. As M2 macrophage-derived exosomes (M2-exos) can actively target inflammatory sites and modulate immune microenvironments, M2-exos can effectively treat periodontitis. Excessive endoplasmic reticulum stress (ER stress) and unfolded protein response (UPR) are highly destructive pathological characteristics during inflammatory periodontal bone loss. Although melatonin has antioxidant and anti-inflammatory effects, studies focusing on melatonin ER stress modulation remain limited. This study fabricates engineered M2-exos loading with melatonin (Mel@M2-exos) for treating periodontitis. As a result, M2-exos drive an appropriate and timely macrophage reprogramming from M1 to M2 type, which resolves chronic inflammation and accelerated periodontal healing. Melatonin released from Mel@M2-exos rescues the osteogenic and cementogenic differentiation capacity in inflammatory human periodontal ligament cells (hPDLCs) by reducing excessive ER stress and UPR. Injectable gelatin methacryloyl (GelMA) hydrogels with sustained-release Mel@M2-exos accelerate periodontal bone regeneration in rats with ligation-induced periodontitis. Taken together, melatonin engineering M2 macrophage-derived exosomes are promising candidates for inflammatory periodontal tissue regeneration.

Δ8-THC Protects against Amyloid Beta Toxicity Modulating ER Stress In Vitro: A Transcriptomic Analysis.

Alzheimer's disease (AD) represents the most common form of dementia, characterized by amyloid β (Aβ) plaques and neurofibrillary tangles (NFTs). It is characterized by neuroinflammation, the accumulation of misfolded protein, ER stress and neuronal apoptosis. It is of main importance to find new therapeutic strategies because AD prevalence is increasing worldwide. Cannabinoids are arising as promising neuroprotective phytocompounds. In this study, we evaluated the neuroprotective potential of Δ8-THC pretreatment in an in vitro model of AD through transcriptomic analysis. We found that Δ8-THC pretreatment restored the loss of cell viability in retinoic acid-differentiated neuroblastoma SH-SY5Y cells treated with Aβ1-42. Moreover, the transcriptomic analysis provided evidence that the enriched biological processes of gene ontology were related to ER functions and proteostasis. In particular, Aβ1-42 upregulated genes involved in ER stress and unfolded protein response, leading to apoptosis as demonstrated by the increase in Bax and the decrease in Bcl-2 both at gene and protein expression levels. Moreover, genes involved in protein folding and degradation were also deregulated. On the contrary, Δ8-THC pretreatment reduced ER stress and, as a consequence, neuronal apoptosis. Then, the results demonstrated that Δ8-THC might represent a new neuroprotective agent in AD.

The Role of Sigma‐1‐Receptor in Endoreticulum Stress and Alzheimer's Disease.

AbstractBackgroundOne evident hallmark of Alzheimer's Disease (AD) is the irregular accumulation of proteins such as Aβ and pTau. This accumulation could alleviate ER stress and trigger an integrated signaling cascade called the unfolded protein response (UPR). UPR reduces the number of misfolded proteins and further inhibits abnormal protein accumulation. Targeting ER stress may therefore be an effective treatment for AD. One protein of interest that plays a role in modulating ER stress is the Sigma‐1 receptor (Sig1R). Sig1R agonists have been shown to be neuroprotective and anti‐amnesic in AD mouse models. However, the mechanism of action remains largely unknown.MethodIn our study, we use primary MEF cells derived from Wild‐type and Knock‐out Sig1R mouse models to examine the role of Sig1R in ER stress. We treated cells with an acute ER stressor, DTT, and measured transcript levels of target genes under the UPR branches. Furthermore, we used Chromosomal Immunoprecipitation (ChIP) to identify regulators of SIG1R gene during stress.ResultWe observed that the loss of Sig1R compromised the PERK pathway. KO MEFs had a slow recovery from stress suggesting Sig1R plays a role in re‐establishing homeostasis following stress. Following DTT treatment, mRNA and protein levels of Sig1R increase significantly over the course of recovery. ChIP uncovered three CHOP, a major player in the UPR, binding sites within the promoter of SIG1R, and each site had a distinct temporal binding pattern over the course of cell recovery. This increase in binding correlates with an increase in Sig1R expression. This showed that Sig1R is a chaperone downstream of CHOP, and that the up‐regulation of Sig1R might be crucial in re‐establishing homeostasis. Finally, our imaging data showed an increase in localization of Sig1R with extracellular vesicles. We further hypothesized that the high expression of Sig‐1R may have a role in the removal of misfolded proteins, perhaps Aβ. Therefore, we have ongoing experiments looking at the effect of Aβ on our models.ConclusionOur study has the potential to unravel the implications of Sig1R in AD by showing that it is transcriptionally and translationally regulated in response to stress induced by misfolded proteins.

Comparison between aerobic exercise training and enalapril treatment as tools to improve diet-induced metabolic-associated fatty liver disease: Effects on endoplasmic reticulum stress markers

AimsEndoplasmic reticulum (ER) stress poses a new pathological mechanism for metabolic-associated fatty liver disease (MAFLD). MAFLD treatment has encompassed renin-angiotensin system (RAS) blockers and aerobic exercise training, but their association with hepatic ER stress is not well known. Therefore, we aimed to compare the effects of hepatic RAS modulation by enalapril and/or aerobic exercise training over ER stress in MAFLD caused by a diet-induced obesity model. Main methodsC57BL/6 mice were fed a standard-chow (CON, n = 10) or a high-fat (HF, n = 40) diet for 8 weeks. HF group was then randomly divided into: HF (n = 10), HF + Enalapril (EN, n = 10), HF + Aerobic exercise training (AET, n = 10), and HF + Enalapril+Aerobic exercise training (EN + AET, n = 10) for 8 more weeks. Body mass (BM) and glucose profile were evaluated. In the liver, ACE and ACE2 activity, morphology, lipid profile, and protein expression of ER stress and metabolic markers were assessed. Key findingsBoth enalapril and aerobic exercise training provided comparable efficacy in improving diet-induced MAFLD through modulation of RAS and ER stress, but the latter was more efficient in improving ER stress, liver damage and metabolism. SignificanceThis is the first study to evaluate pharmacological (enalapril) and non-pharmacological (aerobic exercise training) RAS modulators associated with ER stress in a diet-induced MAFLD model.

Endoplasmic reticulum‐stress and unfolded protein response‐activation in immune‐mediated necrotizing myopathy

Patients suffering from immune-mediated necrotizing myopathies (IMNM) harbor, the pathognomonic myositis-specific auto-antibodies anti-SRP54 or -HMGCR, while about one third of them do not. Activation of chaperone-assisted autophagy was described as being part of the molecular etiology of IMNM. Endoplasmic reticulum (ER)/sarcoplasmic reticulum (SR)-stress accompanied by activation of the unfolded protein response (UPR) often precedes activation of the protein clearance machinery and represents a cellular defense mechanism toward restoration of proteostasis. Here, we show that ER/SR-stress may be part of the molecular etiology of IMNM. To address this assumption, ER/SR-stress related key players covering the three known branches (PERK-mediated, IRE1-mediated, and ATF6-mediated) were investigated on both, the transcript and the protein levels utilizing 39 muscle biopsy specimens derived from IMNM-patients. Our results demonstrate an activation of all three UPR-branches in IMNM, which most likely precedes the activation of the protein clearance machinery. In detail, we identified increased phosphorylation of PERK and eIF2a along with increased expression and protein abundance of ATF4, all well-documented characteristics for the activation of the UPR. Further, we identified increased general XBP1-level, and elevated XBP1 protein levels. Additionally, our transcript studies revealed an increased ATF6-expression, which was confirmed by immunostaining studies indicating a myonuclear translocation of the cleaved ATF6-form toward the forced transcription of UPR-related chaperones. In accordance with that, our data demonstrate an increase of downstream factors including ER/SR co-chaperones and chaperones (e.g., SIL1) indicating an UPR-activation on a broader level with no significant differences between seropositive and seronegative patients. Taken together, one might assume that UPR-activation within muscle fibers might not only serve to restore protein homeostasis, but also enhance sarcolemmal presentation of proteins crucial for attracting immune cells. Since modulation of ER-stress and UPR via application of chemical chaperones became a promising therapeutic treatment approach, our findings might represent the starting point for new interventional concepts.

Patchouli alcohol protects against myocardial ischaemia–reperfusion injury by regulating the Notch1/Hes1 pathway

Context Patchouli alcohol (PA) has protective effects on cerebral ischaemia/reperfusion (I/R) injury, but its efficacy on myocardial ischaemia-reperfusion (MI/R) has yet to be addressed. Objective To examine the therapeutic effect of PA on myocardial ischaemia-reperfusion (I/R) injury. Materials and methods C57BL/6 male mice were randomly divided into sham, MI/R, MI/R + PA-10, MI/R + PA-20 and MI/R + PA-40 groups. In vivo MI/R model was established by ligating the anterior descending coronary artery of the heart. In vitro stimulated IR cell model was constructed by using the rat cardiomyocyte H9C2 cell line. Mice in the treatment groups were intraperitoneally injected with PA (10, 20, 40 mg/kg) for 30 days then subjected to surgery, and cells in the experimental group were pre-treated with PA (1, 10 or 100 μmol/L). After treatment, mouse heart function, myocardial injury markers, myocardial infarction and Notch1/Hes1 expression, endoplasmic reticulum stress markers, and apoptosis-related proteins were determined. Results In vivo, PA treatment improved hemodynamic parameter changes and myocardial enzymes, increased the left ventricular ejection fraction and left ventricular fractional shortening, reduced the left ventricular end-systolic diameter and inhibited CK-MB, cTnI and cTnT levels. In addition, PA attenuated myocardial tissue damage and apoptosis. PA treatment elevated Notch1, NICD and Hes1 levels and suppressed the levels of ATF4, p-PERK/PERK, and cleaved caspase-3/caspase-3 in vitro and in vivo. Discussion and conclusion PA protects against MI/R, possibly by modulating ER stress, apoptosis and the Notch1/Hes1 signalling pathways. These findings indicate that PA may be a promising candidate for treating ischaemic heart diseases.

Dexmedetomidine and Ketamine Attenuated Neuropathic Pain Related Behaviors via STING Pathway to Induce ER-Phagy.

Our previous work indicated that ER-phagy level had altered in spinal nerve ligation (SNL) rats. In this study, we investigated whether dexmedetomidine or ketamine exhibits anti-anxiety or anti-nociceptive effects via modulation of the spinal STING/TBK pathway to alter ER-phagy in SNL rats. We evaluated the analgesic and anti-anxiety effects of ketamine and dexmedetomidine in SNL rats. 2’3’-cGAMP (a STING pathway agonist) was administrated to investigate whether enhanced spinal STING pathway activation could inhibit dexmedetomidine or ketamine treatment effects in SNL rats. Analgesic effects were assessed with the mechanical withdrawal threshold (MWT) and anti-anxiety effects were measured via an open field test (OFT). Protein expression levels were evaluated by immunoblotting. Distribution and cellular localization of Grp78 (ER stress marker) were evaluated by confocal immunofluorescence. SNL induced mechanical hypersensitivity and anxiety in rats; dexmedetomidine and ketamine both provided analgesia and anti-anxiety effects in SNL rats. Furthermore, the STING pathway was involved in the modulation of ER stress and ER-phagy in SNL rats and dexmedetomidine and ketamine alleviated ER stress by inhibiting STING pathway to enhance ER-phagy. Thus, both ketamine and dexmedetomidine provided anti-anxiety and anti-nociceptive effects by alleviating ER stress through the inhibition of the STING/TBK pathway to modulate spinal ER-phagy in SNL rats.