Antioxidants reduce endoplasmic reticulum stress and improve protein secretion. Proc Natl Acad Sci U S A. 2008;105:18525-18530. [PMID: 19011102 DOI: 10.1073/pnas.0809677105]

Increased clearance of non-biodegradable polystyrene nanoplastics by exocytosis through inhibition of retrograde intracellular transport

Nanoplastics (NPs) are derived from microplastics and may cause health problems. We previously showed that 100 nm polystyrene (PS)-NPs enter cells, including mouse embryonic fibroblasts (MEFs), and their intracellular accumulation induces inflammatory and oxidative stress. Moreover, PS-NP uptake was found to occur via endocytosis, and they accumulated mostly at the juxtanuclear position, but never within the nucleus. We speculated that PS-NPs were cleared from cells when they were no longer exposed to PS-NPs. However, the effects of PS-NPs on the cellular machinery remain unknown. The accumulation of PS-NPs at the juxtanuclear position may be due to retrograde transport along microtubules. To confirm this, we treated PS-NP-exposed MEFs with inhibitors of histone deacetylase 6 (HDAC6), dynein, or microtubule polymerization and found greatly diminished intracellular and juxtanuclear accumulation. Moreover, rapid clearance of PS-NPs was observed when MEFs were treated with an HDAC6 inhibitor. PS-NPs were removed by exocytosis, as confirmed by treatment with an exocytosis inhibitor. Furthermore, inhibiting the retrograde transport of PS-NPs alleviated the activation of the antioxidant response pathway, inflammatory and oxidative stress, and reactive oxygen species generation. In summary, inhibition of the retrograde transport of non-biodegradable PS-NPs leads to their rapid export by exocytosis, which may reduce their cytotoxicity.

ER Redox Homeostasis Regulates Proinsulin Trafficking and Insulin Granule Formation in the Pancreatic Islet β-Cell

Defects in the pancreatic β-cell's secretion system are well-described in type 2 diabetes (T2D) and include impaired proinsulin processing and a deficit in mature insulin-containing secretory granules; however, the cellular mechanisms underlying these defects remain poorly understood. To address this, we used an in situ fluorescent pulse-chase strategy to study proinsulin trafficking. We show that insulin granule formation and the appearance of nascent granules at the plasma membrane are decreased in rodent and cell culture models of prediabetes and hyperglycemia. Moreover, we link the defect in insulin granule formation to an early trafficking delay in endoplasmic reticulum (ER) export of proinsulin, which is independent of overt ER stress. Using a ratiometric redox sensor, we show that the ER becomes hyperoxidized in β-cells from a dietary model of rodent prediabetes and that addition of reducing equivalents restores ER export of proinsulin and insulin granule formation and partially restores β-cell function. Together, these data identify a critical role for the regulation of ER redox homeostasis in proinsulin trafficking and suggest that alterations in ER redox poise directly contribute to the decline in insulin granule production in T2D. This model highlights a critical link between alterations in ER redox and ER function with defects in proinsulin trafficking in T2D. Hyperoxidation of the ER lumen, shown as hydrogen peroxide, impairs proinsulin folding and disulfide bond formation that prevents efficient exit of proinsulin from the ER to the Golgi. This trafficking defect limits available proinsulin for the formation of insulin secretory granules during the development of T2D.

4-PBA rescues hyperoxaluria induced nephrolithiasis by modulating urinary glycoproteins: Cross talk between endoplasmic reticulum, calcium homeostasis and mitochondria

AIM

Urinary glycoproteins such as Tamm Horsfall Protein (THP) and Osteopontin (OPN) are well established key regulators of renal stone formation. Additionally, recent revelations have highlighted the influence of Endoplasmic Reticulum (ER) and mitochondria of crucial importance in nephrolithiasis. However, till date conclusive approach highlighting the influence of ER stress on urinary glycoproteins and chaperone in nephrolithiasis remains elusive. Therefore, the present study was focussed on deciphering the possible effect of 4-PBA mitigating ER stress on urinary glycoproteins and calnexin (chaperone) with emphasis on interlinking calcium homeostasis in hyperoxaluric rats.

MATERIAL AND METHODS

Post 9 days of treatment, animals were sacrificed, and renal tissues were investigated for urinary glycoproteins, calnexin, calcium homeostasis, ER environment, redox status, and mitochondrial linkage.

KEY FINDINGS

4-PBA appreciably reversed the altered levels of THP, OPN, and calnexin observed along with curtailing the disrupted calcium homeostasis when assessed for SERCA activity and intra-cellular calcium levels. Additionally, significant improvement in the perturbed ER environment as verified by escalated ER stress markers, disturbed protein folding-aggregation-degradation (congo red assay) pathway, and redox status was found post 4-PBA intervention. Interestingly, linkage of ER stress and mitochondria was established under hyperoxaluric conditions when assessed for protein levels of VDAC1 and GRP75.

SIGNIFICANCE

4-PBA treatment resulted in rectifying the repercussions of ER-mitochondrial caused distress when assessed for protein folding/aggregation/degradation events along with disturbed calcium homeostasis. The present study advocates the necessity to adopt a holistic vision towards hyperoxaluria with emphasis on glycoproteins and ER environment.

Elevated homocysteine activates unfolded protein responses and causes aberrant trophoblast differentiation and mouse blastocyst development

Hyperhomocysteinemia may arise from folate/vitamin B12 deficiency, genetic polymorphisms, kidney disease, or hypothyroidism. It is associated with an increased risk of early pregnancy loss and placenta-related complications of pregnancy, including pre-eclampsia and fetal growth restriction. While the majority of studies of hyperhomocysteinemia focus on epigenetic changes secondary to metabolic disruption, the effects of homocysteine toxicity on placental development remain unexplored. Here, we investigated the influence of hyperhomocysteinemia on early blastocyst development and trophoblast differentiation. Exposure of cultured blastocysts to high homocysteine levels reduces cell number in the trophectoderm layer, most likely through increased apoptosis. Homocysteine also promotes differentiation of a trophoblast stem cell line. Both effects diminish the stem cell pool, and are mediated in an endoplasmic reticulum (ER) unfolded protein response (UPRER )-dependent manner. Targeted alleviation of UPRER may therefore provide a new therapeutic intervention to improve pregnancy outcome in women with hyperhomocysteinemia.

Riboflavin (Vitamin B2) Deficiency Induces Apoptosis Mediated by Endoplasmic Reticulum Stress and the CHOP Pathway in HepG2 Cells

Riboflavin is an essential micronutrient and a precursor of flavin mononucleotide and flavin adenine dinucleotide for maintaining cell homeostasis. Riboflavin deficiency (RD) induces cell apoptosis. Endoplasmic reticulum (ER) stress is considered to induce apoptosis, and C/EBP homologous protein (CHOP) is a key pathway involved in this process. However, whether RD-induced apoptosis is mediated by ER stress and the CHOP pathway remains unclear and needs further investigation. Therefore, the current study presents the effect of RD on ER stress and apoptosis in the human hepatoma cell line (HepG2). Firstly, cells were cultured in a RD medium (4.55 nM riboflavin) and a control (CON) medium (1005 nM riboflavin). We conducted an observation of cell microstructure characterization and determining apoptosis. Subsequently, 4-phenyl butyric acid (4-PBA), an ER stress inhibitor, was used in HepG2 cells to investigate the role of ER stress in RD-induced apoptosis. Finally, CHOP siRNA was transfected into HepG2 cells to validate whether RD triggered ER stress-mediated apoptosis by the CHOP pathway. The results show that RD inhibited cell proliferation and caused ER stress, as well as increased the expression of ER stress markers (CHOP, 78 kDa glucose-regulated protein, activating transcription factor 6) (p < 0.05). Furthermore, RD increased the cell apoptosis rate, enhanced the expression of proapoptotic markers (B-cell lymphoma 2-associated X, Caspase 3), and decreased the expression of the antiapoptotic marker (B-cell lymphoma 2) (p < 0.05). The 4-PBA treatment and CHOP knockdown markedly alleviated RD-induced cell apoptosis. These results demonstrate that RD induces cell apoptosis by triggering ER stress and the CHOP pathway.

ER stress and UPR in Alzheimer's disease: mechanisms, pathogenesis, treatments

Alzheimer's disease (AD) is a devastating neurodegenerative disorder characterized by gradual loss of memory and cognitive function, which constitutes a heavy burden on the healthcare system globally. Current therapeutics to interfere with the underlying disease process in AD is still under development. Although many efforts have centered on the toxic forms of Aβ to effectively tackle AD, considering the unsatisfactory results so far it is vital to examine other targets and therapeutic approaches as well. The endoplasmic reticulum (ER) stress refers to the build-up of unfolded or misfolded proteins within the ER, thus, perturbing the ER and cellular homeostasis. Emerging evidence indicates that ER stress contributes to the onset and development of AD. A thorough elucidation of ER stress machinery in AD pathology may help to open up new therapeutic avenues in the management of this devastating condition to relieve the cognitive dementia symptoms. Herein, we aim at deciphering the unique role of ER stress in AD pathogenesis, reviewing key findings, and existing controversy in an attempt to summarize plausible therapeutic interventions in the management of AD pathophysiology.

Translation termination codons in protein synthesis and disease

Fidelity of protein synthesis, a process shaped by several mechanisms involving specialized ribosome regions and external factors, ensures the precise reading of sense as well as stop codons (UGA, UAG, UAA), which are usually localized at the 3' of mRNA and drive the release of the polypeptide chain. However, either natural (NTCs) or premature (PTCs) termination codons, the latter arising from nucleotide changes, can undergo a recoding process named ribosome or translational readthrough, which insert specific amino acids (NTCs) or subset(s) depending on the stop codon type (PTCs). This process is particularly relevant for nonsense mutations, a relatively frequent cause of genetic disorders, which impair gene expression at different levels by potentially leading to mRNA degradation and/or synthesis of truncated proteins. As a matter of fact, many efforts have been made to develop efficient and safe readthrough-inducing compounds, which have been challenged in several models of human disease to provide with a therapy. In this view, the dissection of the molecular determinants shaping the outcome of readthrough, namely nucleotide and protein contexts as well as their interplay and impact on protein structure/function, is crucial to identify responsive nonsense mutations resulting in functional full-length proteins. The interpretation of experimental and mechanistic findings is also important to define a possibly clear picture of potential readthrough-favorable features useful to achieve rescue profiles compatible with therapeutic thresholds typical of each targeted disorder, which is of primary importance for the potential translatability of readthrough into a personalized and mutation-specific, and thus patient-oriented, therapeutic strategy.

The repositioned drugs disulfiram/diethyldithiocarbamate combined to benznidazole: Searching for Chagas disease selective therapy, preventing toxicity and drug resistance

Chagas disease (CD) affects at least 6 million people in 21 South American countries besides several thousand in other nations all over the world. It is estimated that at least 14,000 people die every year of CD. Since vaccines are not available, chemotherapy remains of pivotal relevance. About 30% of the treated patients cannot complete the therapy because of severe adverse reactions. Thus, the search for novel drugs is required. Here we tested the benznidazole (BZ) combination with the repositioned drug disulfiram (DSF) and its derivative diethyldithiocarbamate (DETC) upon Trypanosoma cruzi in vitro and in vivo. DETC-BZ combination was synergistic diminishing epimastigote proliferation and enhancing selective indexes up to over 10-fold. DETC was effective upon amastigotes of the BZ- partially resistant Y and the BZ-resistant Colombiana strains. The combination reduced proliferation even using low concentrations (e.g., 2.5 µM). Scanning electron microscopy revealed membrane discontinuities and cell body volume reduction. Transmission electron microscopy revealed remarkable enlargement of endoplasmic reticulum cisternae besides, dilated mitochondria with decreased electron density and disorganized kinetoplast DNA. At advanced stages, the cytoplasm vacuolation apparently impaired compartmentation. The fluorescent probe H2-DCFDA indicates the increased production of reactive oxygen species associated with enhanced lipid peroxidation in parasites incubated with DETC. The biochemical measurement indicates the downmodulation of thiol expression. DETC inhibited superoxide dismutase activity on parasites was more pronounced than in infected mice. In order to approach the DETC effects on intracellular infection, peritoneal macrophages were infected with Colombiana trypomastigotes. DETC addition diminished parasite numbers and the DETC-BZ combination was effective, despite the low concentrations used. In the murine infection, the combination significantly enhanced animal survival, decreasing parasitemia over BZ. Histopathology revealed that low doses of BZ-treated animals presented myocardial amastigote, not observed in combination-treated animals. The picrosirius collagen staining showed reduced myocardial fibrosis. Aminotransferase de aspartate, Aminotransferase de alanine, Creatine kinase, and urea plasma levels demonstrated that the combination was non-toxic. As DSF and DETC can reduce the toxicity of other drugs and resistance phenotypes, such a combination may be safe and effective.

Using analogue data to substantiate long-term durability of gene therapies: a narrative review

The number of gene therapies in clinical trials and moving toward licensure is increasing. Most gene therapies are designed to achieve long-term effects, but at licensure the data to support claims of long-term durability are often limited, as long-term monitoring studies are often part of post-approval commitments by companies. Health technology assessors must therefore assess the potential for the long-term durability of a product and the potential cost-effectiveness based on the data available. The authors explored the benefit of strengthening the ability to infer durability of effect using analogue category data. Different analogue categories were assessed for the potential to substantiate claims of sustainability of effect for gene therapies by leveraging biological plausibility arguments. The authors propose a pathway for identifying potential analogues. Such a pathway should help establish plausible or theoretical long-term outcomes that can be considered in value assessments of gene therapies.

Endoplasmic Reticulum Stress, Oxidative Stress, and Rheumatic Diseases

BACKGROUND

The endoplasmic reticulum (ER) is a multi-functional organelle responsible for cellular homeostasis, protein synthesis, folding and secretion. It has been increasingly recognized that the loss of ER homeostasis plays a central role in the development of autoimmune inflammatory disorders, such as rheumatic diseases. Purpose/Main contents: Here, we review current knowledge of the contribution of ER stress to the pathogenesis of rheumatic diseases, with a focus on rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). We also review the interplay between protein folding and formation of reactive oxygen species (ROS), where ER stress induces oxidative stress (OS), which further aggravates the accumulation of misfolded proteins and oxidation, in a vicious cycle. Intervention studies targeting ER stress and oxidative stress in the context of rheumatic diseases are also reviewed.

CONCLUSIONS

Loss of ER homeostasis is a significant factor in the pathogeneses of RA and SLE. Targeting ER stress, unfolded protein response (UPR) pathways and oxidative stress in these diseases both in vitro and in animal models have shown promising results and deserve further investigation.

Production of Plant Sesquiterpene Lactone Parthenolide in the Yeast Cell Factory

Parthenolide, a kind of sesquiterpene lactone, is the direct precursor for the promising anti-glioblastoma drug ACT001. Compared with traditional parthenolide source from plant extraction, de novo biosynthesis of parthenolide in microorganisms has the potential to make a sustainable supply. Herein, an integrated strategy was designed with P450 source screening, nicotinamide adenine dinucleotide phosphate (NADPH) supply, and endoplasmic reticulum (ER) size rewiring to manipulate three P450s regarded as the bottleneck for parthenolide production. Germacrene A oxidase from Cichorium intybus, costunolide synthase from Lactuca sativa, and parthenolide synthase from Tanacetum parthenium have the best efficiency, resulting in a parthenolide titer of 2.19 mg/L, which was first achieved in yeast. The parthenolide titer was further increased by 300% with NADPH supplementation and ER expanding stepwise. Finally, the highest titers of 31.0 mg/L parthenolide and 648.5 mg/L costunolide in microbes were achieved in 2.0 L fed-batch fermentation. This study not only provides an alternative microbial platform for producing sesquiterpene lactones in a sustainable way but also highlights a general strategy for manipulating multiple plant-derived P450s in microbes.

ELOVL5-mediated fatty acid elongation promotes cellular proliferation and invasion in renal cell carcinoma

Renal cell carcinoma (RCC) features altered lipid metabolism and accumulated polyunsaturated fatty acids (PUFAs). Elongation of very long–chain fatty acid (ELOVL) family enzymes catalyze fatty acid elongation, and ELOVL5 is indispensable for PUFAs elongation, but its role in RCC progression remains unclear. Here, we show that higher levels of ELOVL5 correlate with poor RCC clinical prognosis. Liquid chromatography/electrospray ionization‐tandem mass spectrometry analysis showed decreases in ELOVL5 end products (arachidonic acid and eicosapentaenoic acid) under CRISPR/Cas9‐mediated knockout of ELOVL5 while supplementation with these fatty acids partially reversed the cellular proliferation and invasion effects of ELOVL5 knockout. Regarding cellular proliferation and invasion, CRISPR/Cas9‐mediated knockout of ELOVL5 suppressed the formation of lipid droplets and induced apoptosis via endoplasmic reticulum stress while suppressing renal cancer cell proliferation and in vivo tumor growth. Furthermore, CRISPR/Cas9‐mediated knockout of ELOVL5 inhibited AKT Ser473 phosphorylation and suppressed renal cancer cell invasion through chemokine (C‐C motif) ligand‐2 downregulation by AKT‐mTOR‐STAT3 signaling. Collectively, these results suggest that ELOVL5‐mediated fatty acid elongation promotes not only cellular proliferation but also invasion in RCC.

Metabolic Engineering of Saccharomyces cerevisiae for Heterologous Carnosic Acid Production

Carnosic acid (CA), a phenolic tricyclic diterpene, has many biological effects, including anti-inflammatory, anticancer, antiobesity, and antidiabetic activities. In this study, an efficient biosynthetic pathway was constructed to produce CA in Saccharomyces cerevisiae. First, the CA precursor miltiradiene was synthesized, after which the CA production strain was constructed by integrating the genes encoding cytochrome P450 enzymes (P450s) and cytochrome P450 reductase (CPR) SmCPR. The CA titer was further increased by the coexpression of CYP76AH1 and SmCPR ∼t28SpCytb5 fusion proteins and the overexpression of different catalases to detoxify the hydrogen peroxide (H₂O₂). Finally, engineering of the endoplasmic reticulum and cofactor supply increased the CA titer to 24.65 mg/L in shake flasks and 75.18 mg/L in 5 L fed-batch fermentation. This study demonstrates that the ability of engineered yeast cells to synthesize CA can be improved through metabolic engineering and synthetic biology strategies, providing a theoretical basis for microbial synthesis of other diterpenoids.

Gene therapy - are we ready now?

Introduction

Haemophilia therapy has evolved from rudimentary transfusion‐based approaches to an unprecedented level of innovation with glimmers of functional cure brought by gene therapy. After decades of misfires, gene therapy has normalized factor (F)VIII and factor (F)IX levels in some individuals in the long term. Several clinical programmes testing adeno‐associated viral (AAV) vector gene therapy are approaching completion with imminent regulatory approvals.

Discussion

Phase 3 studies along with multiyear follow‐up in earlier phase investigations raised questions about efficacy as well as short‐ and long‐term safety, prompting a reappraisal of AAV vector gene therapy. Liver toxicities, albeit mostly low‐grade, occur in the first year in at least some individuals in all haemophilia A and B trials and are poorly understood. Extreme variability and unpredictability of outcome, as well as a slow decline in factor expression (seemingly unique to FVIII gene therapy), are vexing because immune responses to AAV vectors preclude repeat dosing, which could increase suboptimal or restore declining expression, while overexpression may result in phenotoxicity. The long‐term safety will need lifelong monitoring because AAV vectors, contrary to conventional wisdom, integrate into chromosomes at the rate that calls for vigilance.

Conclusions

AAV transduction and transgene expression engage the host immune system, cellular DNA processing, transcription and translation machineries in ways that have been only cursorily studied in the clinic. Delineating those mechanisms will be key to finding mitigants and solutions to the remaining problems, and including individuals who cannot avail of gene therapy at this time.

Molecular therapeutics of Hemophilia A and B

INTRODUCTION

Hemophilia A (HA) or B (HB) is an X-linked recessive disorder caused by a defect in the factor VIII (FVIII) or factor IX (FIX) gene which leads to the dysfunction of blood coagulation. Protein replacement therapy (PRT) uses recombinant proteins and plasma-derived products, which incurs high cost and inconvenience requiring routine intravenous infusions and life-time treatment. Understanding of detailed molecular mechanisms on FVIII gene function could provide innovative solutions to amend this disorder. In recent decades, gene therapeutics have advanced rapidly and a one-time cure solution has been proposed.

AREAS COVERED

This review summarizes current understanding of molecular pathways involved in blood coagulation, with emphasis on FVIII's functional role. The existing knowledge and challenges on FVIII gene expression, from transcription, translation, post-translational modification including glycosylation to protein processing and secretion, and co-factor interactions are deciphered and potential molecular interventions discussed.

EXPERT OPINION

This article reviews the potential treatment targets for HA and HB, including antibodies, small molecules and gene therapeutics, based on molecular mechanisms of FVIII biosynthesis, and further, assessing the pros and cons of these various treatment strategies. Understanding detailed FVIII protein synthesis and secretory pathways could provide exciting opportunities in identifying novel therapeutics to ameliorate hemophilia state.

Antioxidant Responses are Crucial for Defense against Misfolded Human Z-Type α1-Antitrypsin

Backgrounds:

The Z-type variant of human α1-antitrypsin is involved in liver cirrhosis and pulmonary emphysema. Due to its slow folding characteristics, this variant accumulates folding intermediates and forms protein aggregates within hepatocytes. Misfolded proteins may induce oxidative stress and subsequent cell death.

Objective:

The potential application of antioxidant response signaling pathway and antioxidants to cope with Z-type α1-antitrypsin-induced oxidative stress was evaluated.

Methods:

Overexpression of Z-type α1-antitrypsin in Saccharomyces cerevisiae provoked oxidative stress and increased susceptibility to oxidative challenges such as hydrogen peroxide treatment. Deletion of antioxidant-response genes, including yap1, skn7, sod2, tsa1, and pst2, exacerbated the slow growth phenotype of Z-type α1-antitrypsin-expressing cells. Antioxidant treatment alleviated oxidative stress and cytotoxicity induced by Z-type α1-antitrypsin.

Results:

Our results show that cellular antioxidant capacity is crucial to protection against misfolded Z-type α1-antitrypsin.

Conclusion:

The information obtained here may be used to prevent oxidative stress caused by misfolded proteins, which are associated with several degenerative diseases, including amyotrophic lateral sclerosis and Parkinson’s disease.

Interindividual variability in transgene mRNA and protein production following adeno-associated virus gene therapy for hemophilia A

Factor VIII gene transfer with a single intravenous infusion of valoctocogene roxaparvovec (AAV5-hFVIII-SQ) has demonstrated clinical benefits lasting 5 years to date in people with severe hemophilia A. Molecular mechanisms underlying sustained AAV5-hFVIII-SQ-derived FVIII expression have not been studied in humans. In a substudy of the phase 1/2 clinical trial (NCT02576795), liver biopsy samples were collected 2.6–4.1 years after gene transfer from five participants. Primary objectives were to examine effects on liver histopathology, determine the transduction pattern and percentage of hepatocytes transduced with AAV5-hFVIII-SQ genomes, characterize and quantify episomal forms of vector DNA and quantify transgene expression (hFVIII-SQ RNA and hFVIII-SQ protein). Histopathology revealed no dysplasia, architectural distortion, fibrosis or chronic inflammation, and no endoplasmic reticulum stress was detected in hepatocytes expressing hFVIII-SQ protein. Hepatocytes stained positive for vector genomes, showing a trend for more cells transduced with higher doses. Molecular analysis demonstrated the presence of full-length, inverted terminal repeat-fused, circular episomal genomes, which are associated with long-term expression. Interindividual differences in transgene expression were noted despite similar successful transduction, possibly influenced by host-mediated post-transduction mechanisms of vector transcription, hFVIII-SQ protein translation and secretion. Overall, these results demonstrate persistent episomal vector structures following AAV5-hFVIII-SQ administration and begin to elucidate potential mechanisms mediating interindividual variability.

The analysis of liver biopsy samples after AAV gene therapy for hemophilia A reveals normal histology and long-term persistence of the episomal vector, and identifies potential factors contributing to interindividual variability of transgene expression.

The Biphasic Effect of Flavonoids on Oxidative Stress and Cell Proliferation in Breast Cancer Cells

Flavonoids have been reported to play an essential role in modulating processes of cellular redox homeostasis such as scavenging ROS. Meanwhile, they also induce oxidative stress that exerts potent antitumor bioactivity. However, the contradiction between these two aspects still remains unclear. In this study, four typical flavonoids were selected and studied. The results showed that low-dose flavonoids slightly promoted the proliferation of breast cancer cells under normal growth via gradually reducing accumulated oxidative products and demonstrated a synergistic effect with reductants NAC or VC. Besides, low-dose flavonoids significantly reduced the content of ROS and MDA induced by LPS or Rosup but restored the activity of SOD. However, high-dose flavonoids markedly triggered the cell death via oxidative stress as evidenced by upregulated ROS, MDA and downregulated SOD activity that could be partly rescued by NAC pretreatment, which was also confirmed by antioxidative gene expression levels. The underlying mechanism of such induced cell death was pinpointed as apoptosis, cell cycle arrest, accumulated mitochondrial superoxide, impaired mitochondrial function and decreased ATP synthesis. Transcriptomic analysis of apigenin and quercetin uncovered that high-dose flavonoids activated TNF-α signaling, as verified through detecting inflammatory gene levels in breast cancer cells and RAW 264.7 macrophages. Moreover, we identified that BRCA1 overexpression effectively attenuated such oxidative stress, inflammation and inhibited ATP synthesis induced by LPS or high dose of flavonoids possibly through repairing DNA damage, revealing an indispensable biological function of BRCA1 in resisting oxidative damage and inflammatory stimulation caused by exogenous factors.

Combination therapy based on targeted nano drug co-delivery systems for liver fibrosis treatment: A review

Liver fibrosis is the hallmark of liver disease and occurs prior to the stages of cirrhosis and hepatocellular carcinoma. Any type of liver damage or inflammation can result in fibrosis. Fibrosis does not develop overnight, but rather as a result of the long-term action of injury factors. At present, however, there are no good treatment methods or specific drugs other than removing the pathogenic factors. Drug application is still limited, which means that drugs with good performance in vitro cannot achieve good therapeutic effects in vivo, owing to various factors such as poor drug targeting, large side effects, and strong hydrophobicity. Hepatic stellate cells (HSC) are the primary effector cells in liver fibrosis. The nano-drug delivery system is a new and safe drug delivery system that has many advantages which are widely used in the field of liver fibrosis. Drug resistance and side effects can be reduced when two or more drugs are used in combination drug delivery. Combination therapy of drugs with different targets has emerged as a novel approach to treating liver fibrosis, and the nano co-delivery system enhances the benefits of combination therapy. While nano co-delivery systems can maximize benefits while avoiding drug side effects, this is precisely the advantage of the nano co-delivery system. This review briefly described the pathogenesis and current treatment strategies, the different co-delivery systems of combination drugs in the nano delivery system, and targeting strategies for nano delivery systems on liver fibrosis therapy. Because of their superior performance, nano delivery systems and targeting drug delivery systems have received a lot of attention in the new drug delivery system. The new delivery systems offer a new pathway in the treatment of liver fibrosis, and it is believed that it can be a new treatment for fibrosis in the future. Nano co-delivery system of combination drugs and targeting strategies has proven the effectiveness of anti-fibrosis at the experimental level.

Dihydroartemisinin Induces ER Stress-Mediated Apoptosis in Human Tongue Squamous Carcinoma by Regulating ROS Production

BACKGROUND

Tongue squamous cell carcinoma is a fatal disease characterized by high invasion and early metastasis. Dihydroartemisinin, an antimalarial drug with multiple biological activities, is reported to be a potential anti-cancer agent.

OBJECTIVE

This study aimed to evaluate the antitumor effect of Dihydroartemisinin on tongue squamous cell carcinoma cells, and to identify the underlying mechanisms of Dihydroartemisinin-induced cell apoptosis.

METHODS

Here, Cell Counting Kit 8 assay and colony formation assay were conducted to study cell proliferation. Annexin V-FITC/propidium iodide staining and western blot analysis were performed to analyze cell apoptosis. DCFH-DA probe was used to measure the generation of cellular reactive oxygen species. Endoplasmic reticulum stress activation was also determined via western blot analysis.

RESULTS

The results showed that Dihydroartemisinin substantially inhibited cell proliferation and induced cell apoptosis in vivo. Moreover, reactive oxygen species production and endoplasmic reticulum stress activation were both observed after stimulation with Dihydroartemisinin. However, the reactive oxygen species inhibitor N-acetylcysteine significantly alleviated Dihydroartemisinin-induced endoplasmic reticulum stress and apoptosis.

CONCLUSION

These results imply that Dihydroartemisinin induced cell apoptosis by triggering reactive oxygen species-mediated endoplasmic reticulum stress in CAL27 cells. In addition, Dihydroartemisinin might be an effective drug for tongue squamous cell carcinoma therapy.

Lutein activates downstream signaling pathways of unfolded protein response in hyperglycemic ARPE-19 cells

We have earlier demonstrated that lutein effectively prevents hyperglycemia generated sustained oxidative stress in ARPE-19 cells by activating Nrf2 (nuclear factor erythroid 2-related factor 2) signaling. Since evidence portrays an intricate connection between ER (endoplasmic reticulum) stress and hyperglycemia-mediated oxidative stress, we aimed to explore the protective mechanism of lutein on hyperglycemia-induced ER stress in ARPE-19 cells. To determine the effect of lutein, we probed three major downstream branches of unfolded protein response (UPR) signaling pathways using western blot, immunofluorescent and RT-PCR techniques. The data showed a reduction (38%) in protein expression of an imperative ER chaperon, BiP (binding immunoglobulin protein), in glucose-treated ARPE-19 cells. At the same time, lutein pretreatment blocked this glucose-mediated effect, leading to a significant increase in BiP expression. Lutein promoted the phosphorylation of IRE1 (inositol requiring enzyme 1) and subsequent splicing of XBP1 (X-box binding protein 1), leading to enhanced nuclear translocation. Likewise, lutein activated the expression and translocation of transcription factors, ATF6 (activating transcription factor 6) and ATF4 (activating transcription factor 4) suppressed by hyperglycemia. Lutein also increased CHOP (C/EBP-homologous protein) levels in ARPE-19 cultured under high glucose conditions. The mRNA expression study showed that lutein pretreatment upregulates downstream UPR genes HRD1 (ERAD-associated E3 ubiquitin-protein ligase HRD1), p58^IPK (protein kinase inhibitor p58) compared to high glucose treatment alone. From our study, it is clear that lutein show protection against hyperglycemia-mediated ER stress in ARPE-19 cells by activating IRE1-XBP1, ATF6, and ATF4 pathways and their downstream activators. Thus, lutein may have the pharmacological potential for protection against widespread disease conditions of ER stress.

Small molecule epigenetic modulators for enhancing recombinant antibody production in CHO cell cultures

Small molecule epigenetic modulators that modify epigenetic states in cells are useful tools for regulating gene expression by inducing chromatin remodeling. To identify small molecule epigenetic modulators that enhance recombinant protein expression in CHO cells, we examined eight histone deacetylase inhibitors (iHDACs) and six DNA methyltransferase inhibitors as chemical additives in recombinant CHO (rCHO) cell cultures. Among these, a benzamide-based iHDAC, CI994, was the most effective in increasing monoclonal antibody (mAb) production. Despite suppressing cell growth, the addition of CI994 to mAb-expressing GSR cell cultures at 10 μM resulted in a 2.3-fold increase in maximum mAb concentration due to a 3.0-fold increase in specific mAb productivity (q _mAb ). CI994 increased mAb mRNA levels and histone H3 acetylation in GSR cells, and ChIP-qPCR analysis revealed that CI994 significantly increased the histone H3 acetylation level at the CMV promoter driving mAb gene expression, indicating that chromatin remodeling in the promoter region results in enhanced mAb gene transcription and q _mAb . Similar beneficial effects of CI994 on mAb production were observed in mAb-expressing CS13-1.00 cells. Collectively, our findings indicate that CI994 increases mAb production in rCHO cell cultures by chromatin remodeling resulting from acetylation of histones in the mAb gene promoter. This article is protected by copyright. All rights reserved.

Chinese Herbal Medicine Alleviates Myocardial Ischemia/Reperfusion Injury by Regulating Endoplasmic Reticulum Stress

Myocardial ischemia/reperfusion injury is the main cause of increased mortality and disability in cardiovascular diseases. The injury involves many pathological processes, such as oxidative stress, calcium homeostasis imbalance, inflammation, and energy metabolism disorders, and these pathological stimuli can activate endoplasmic reticulum stress. In the early stage of ischemia, endoplasmic reticulum stress alleviates the injury as an adaptive survival response, but the long-term stress on endoplasmic reticulum amplifies oxidative stress, inflammation, and calcium overload to accelerate cell damage and apoptosis. Therefore, regulation of endoplasmic reticulum stress may be a mechanism to improve ischemia/reperfusion injury. Chinese herbal medicine has a long history of clinical application and unique advantages in the treatment of ischemic heart diseases. This review focuses on the effect of Chinese herbal medicine on myocardial ischemia/reperfusion injury from the perspective of regulation of endoplasmic reticulum stress.

Proteomic and metabolomic profiling of acute and chronic stress events associated with military exercises

By characterizing physiological changes that occur in warfighters during simulated combat, we can start to unravel the key biomolecular components that are linked to physical and cognitive performance. Viable field-based sensors for the warfighter must be rapid and noninvasive. In an effort to facilitate this, we applied a multiomics pipeline to characterize the stress response in the saliva of warfighters to correlate biomolecular changes with overall performance and health. In this study, two different stress models were observed - one of chronic stress and one of acute stress. In both models, significant perturbations in the immune, metabolic, and protein manufacturing/processing systems were observed. However, when differentiating between stress models, specific metabolites associated with the "fight or flight" response and protein folding were seen to be discriminate of the acute stress model.

Bifidobacterium dentium-derived y-glutamylcysteine suppresses ER-mediated goblet cell stress and reduces TNBS-driven colonic inflammation

Endoplasmic reticulum (ER) stress compromises the secretion of MUC2 from goblet cells and has been linked with inflammatory bowel disease (IBD). Although Bifidobacterium can beneficially modulate mucin production, little work has been done investigating the effects of Bifidobacterium on goblet cell ER stress. We hypothesized that secreted factors from Bifidobacterium dentium downregulate ER stress genes and modulates the unfolded protein response (UPR) to promote MUC2 secretion. We identified by mass spectrometry that B. dentium secretes the antioxidant γ-glutamylcysteine, which we speculate dampens ER stress-mediated ROS and minimizes ER stress phenotypes. B. dentium cell-free supernatant and γ-glutamylcysteine were taken up by human colonic T84 cells, increased glutathione levels, and reduced ROS generated by the ER-stressors thapsigargin and tunicamycin. Moreover, B. dentium supernatant and γ-glutamylcysteine were able to suppress NF-kB activation and IL-8 secretion. We found that B. dentium supernatant, γ-glutamylcysteine, and the positive control IL-10 attenuated the induction of UPR genes GRP78, CHOP, and sXBP1. To examine ER stress in vivo, we first examined mono-association of B. dentium in germ-free mice which increased MUC2 and IL-10 levels compared to germ-free controls. However, no changes were observed in ER stress-related genes, indicating that B. dentium can promote mucus secretion without inducing ER stress. In a TNBS-mediated ER stress model, we observed increased levels of UPR genes and pro-inflammatory cytokines in TNBS treated mice, which were reduced with addition of live B. dentium or γ-glutamylcysteine. We also observed increased colonic and serum levels of IL-10 in B. dentium- and γ-glutamylcysteine-treated mice compared to vehicle control. Immunostaining revealed retention of goblet cells and mucus secretion in both B. dentium- and γ-glutamylcysteine-treated animals. Collectively, these data demonstrate positive modulation of the UPR and MUC2 production by B. dentium-secreted compounds.

Multiyear Factor VIII Expression after AAV Gene Transfer for Hemophilia A

BACKGROUND

The goal of gene therapy for patients with hemophilia A is to safely impart long-term stable factor VIII expression that predictably ameliorates bleeding with the use of the lowest possible vector dose.

METHODS

In this phase 1-2 trial, we infused an investigational adeno-associated viral (AAV) vector (SPK-8011) for hepatocyte expression of factor VIII in 18 men with hemophilia A. Four dose cohorts were enrolled; the lowest-dose cohort received a dose of 5  × 10¹¹ vector genomes (vg) per kilogram of body weight, and the highest-dose cohort received 2 × 10¹² vg per kilogram. Some participants received glucocorticoids within 52 weeks after vector administration either to prevent or to treat a presumed AAV capsid immune response. Trial objectives included evaluation of the safety and preliminary efficacy of SPK-8011 and of the expression and durability of factor VIII.

RESULTS

The median safety observation period was 36.6 months (range, 5.5 to 50.3). A total of 33 treatment-related adverse events occurred in 8 participants; 17 events were vector-related, including 1 serious adverse event, and 16 were glucocorticoid-related. Two participants lost all factor VIII expression because of an anti-AAV capsid cellular immune response that was not sensitive to immune suppression. In the remaining 16 participants, factor VIII expression was maintained; 12 of these participants were followed for more than 2 years, and a one-stage factor VIII assay showed no apparent decrease in factor VIII activity over time (mean [±SD] factor VIII activity, 12.9±6.9% of the normal value at 26 to 52 weeks when the participants were not receiving glucocorticoids vs. 12.0±7.1% of the normal value at >52 weeks after vector administration; 95% confidence interval [CI], -2.4 to 0.6 for the difference between matched pairs). The participants had a 91.5% reduction (95% CI, 88.8 to 94.1) in the annualized bleeding rate (median rate, 8.5 events per year [range, 0 to 43.0] before vector administration vs. 0.3 events per year [range, 0 to 6.5] after vector administration).

CONCLUSIONS

Sustained factor VIII expression in 16 of 18 participants who received SPK-8011 permitted discontinuation of prophylaxis and a reduction in bleeding episodes. No major safety concerns were reported. (Funded by Spark Therapeutics and the National Heart, Lung, and Blood Institute; ClinicalTrials.gov numbers, NCT03003533 and NCT03432520.).

Hemophilia A Gene Therapy: Current and Next-Generation Approaches

INTRODUCTION

: Hemophilia comprises a group of X-linked hemorrhagic disorders that result from a deficiency of coagulation factors. The disorder affects mainly males and leads to chronic pain, joint deformity, reduced mobility, and increased mortality. Current therapies require frequent administration of replacement clotting factors, but the emergence of alloantibodies (inhibitors) diminishes their efficacy. New therapies are being developed to produce the deficient clotting factors and prevent the emergence of inhibitors.

AREAS COVERED

: This article provides an update on the characteristics and disease pathophysiology of hemophilia A, as well as current treatments, with a special focus on ongoing clinical trials related to gene replacement therapies.

EXPERT OPINION

: Gene replacement therapies provide safe, durable, and stable transgene expression while avoiding the challenges of clotting factor replacement therapies in patients with hemophilia. Improving the specificity of the viral construct and decreasing the therapeutic dose are critical toward minimizing cellular stress, induction of the unfolded protein response, and the resulting loss of protein production in liver cells. Next-generation gene therapies incorporating chimeric DNA sequences in the transgene can increase clotting factor synthesis and secretion, and advance the efficacy, safety, and durability of gene replacement therapy for hemophilia A as well as other blood clotting disorders.

Discovery of a small molecule inhibitor of cullin neddylation that triggers ER stress to induce autophagy

Protein neddylation is catalyzed by a three-enzyme cascade, namely an E1 NEDD8-activating enzyme (NAE), one of two E2 NEDD8 conjugation enzymes and one of several E3 NEDD8 ligases. The physiological substrates of neddylation are the family members of cullin, the scaffold component of cullin RING ligases (CRLs). Currently, a potent E1 inhibitor, MLN4924, also known as pevonedistat, is in several clinical trials for anti-cancer therapy. Here we report the discovery, through virtual screening and structural modifications, of a small molecule compound HA-1141 that directly binds to NAE in both in vitro and in vivo assays and effectively inhibits neddylation of cullins 1–5. Surprisingly, unlike MLN4924, HA-1141 also triggers non-canonical endoplasmic reticulum (ER) stress and PKR-mediated terminal integrated stress response (ISR) to activate ATF4 at an early stage, and to inhibit protein synthesis and mTORC1 activity at a later stage, eventually leading to autophagy induction. Biologically, HA-1141 suppresses growth and survival of cultured lung cancer cells and tumor growth in in vivo xenograft lung cancer models at a well-tolerated dose. Taken together, our study has identified a small molecule compound with the dual activities of blocking neddylation and triggering ER stress, leading to growth suppression of cancer cells.

Induction of Premature Cell Senescence Stimulated by High Doses of Antioxidants Is Mediated by Endoplasmic Reticulum Stress

In our previous study, we found that high doses of several substances with antioxidant capacities (Tempol, resveratrol, diphenyleneiodonium) can cause genotoxic stress and induce premature senescence in the human mesenchymal stem cells (MSCs). Here, using whole-transcriptome analysis, we revealed the signs of endoplasmic reticulum stress and unfolded protein response (UPR) in MSCs stressed with Tempol and resveratrol. In addition, we found the upregulation of genes, coding the UPR downstream target APC/C, and E3 ubiquitin ligase that regulate the stability of cell cycle proteins. We performed the molecular analysis, which further confirmed the untimely degradation of APC/C targets (cyclin A, geminin, and Emi1) in MSCs treated with antioxidants. Human fibroblasts responded to antioxidant applications similarly. We conclude that endoplasmic reticulum stress and impaired DNA synthesis regulation can be considered as potential triggers of cell damage and premature senescence stimulated by high-dose antioxidant treatments.

OSMI-1 Enhances TRAIL-Induced Apoptosis through ER Stress and NF-κB Signaling in Colon Cancer Cells

Levels of O-GlcNAc transferase (OGT) and hyper-O-GlcNAcylation expression levels are associated with cancer pathogenesis. This study aimed to find conditions that maximize the therapeutic effect of cancer and minimize tissue damage by combining an OGT inhibitor (OSMI-1) and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). We found that OSMI-1 treatment in HCT116 human colon cancer cells has a potent synergistic effect on TRAIL-induced apoptosis signaling. Interestingly, OSMI-1 significantly increased TRAIL-mediated apoptosis by increasing the expression of the cell surface receptor DR5. ROS-induced endoplasmic reticulum (ER) stress by OSMI-1 not only upregulated CHOP-DR5 signaling but also activated Jun-N-terminal kinase (JNK), resulting in a decrease in Bcl2 and the release of cytochrome c from mitochondria. TRAIL induced the activation of NF-κB and played a role in resistance as an antiapoptotic factor. During this process, O-GlcNAcylation of IκB kinase (IKK) and IκBα degradation occurred, followed by translocation of p65 into the nucleus. However, combination treatment with OSMI-1 counteracted the effect of TRAIL-mediated NF-κB signaling, resulting in a more synergistic effect on apoptosis. Therefore, the combined treatment of OSMI-1 and TRAIL synergistically increased TRAIL-induced apoptosis through caspase-8 activation. Conclusively, OSMI-1 potentially sensitizes TRAIL-induced cell death in HCT116 cells through the blockade of NF-κB signaling and activation of apoptosis through ER stress response.

The transcription factor Xrp1 is required for PERK-mediated antioxidant gene induction in Drosophila

PERK is an endoplasmic reticulum (ER) transmembrane sensor that phosphorylates eIF2α to initiate the Unfolded Protein Response (UPR). eIF2α phosphorylation promotes stress-responsive gene expression most notably through the transcription factor ATF4 that contains a regulatory 5’ leader. Possible PERK effectors other than ATF4 remain poorly understood. Here, we report that the bZIP transcription factor Xrp1 is required for ATF4-independent PERK signaling. Cell-type-specific gene expression profiling in Drosophila indicated that delta-family glutathione-S-transferases (gstD) are prominently induced by the UPR-activating transgene Rh1^G69D. Perk was necessary and sufficient for such gstD induction, but ATF4 was not required. Instead, Perk and other regulators of eIF2α phosphorylation regulated Xrp1 protein levels to induce gstDs. The Xrp1 5’ leader has a conserved upstream Open Reading Frame (uORF) analogous to those that regulate ATF4 translation. The gstD-GFP reporter induction required putative Xrp1 binding sites. These results indicate that antioxidant genes are highly induced by a previously unrecognized UPR signaling axis consisting of PERK and Xrp1.

Endoplasmic reticulum stress induces hepatic steatosis by transcriptional upregulating lipid droplet protein perilipin2

Previous studies have shown that endoplasmic reticulum (ER) stress contributes to hepatic steatosis in several manners. However, how lipid droplet (LD) proteins participate in this process has rarely been reported. In the present study, ER stress was induced at both in vitro and in vivo levels with tunicamycin in large yellow croaker (Larimichthys crocea). Effects of LD protein perilipin2 (PLIN2) on hepatic lipid accumulation and lipoprotein transport under normal physiological condition and ER stress were then explored using dsRNA mediated knockdown. Subsequently, the transcriptional regulation of plin2 expression by transcription factors generated in the unfolded protein response (UPR) was determined by dual-luciferase reporter assays, chromatin immunoprecipitation and electrophoretic mobility-shift assay. We demonstrated that ER stress could promote LDs accumulation and inhibit lipoprotein transport by transcriptionally upregulating PLIN2 in liver. Among the transcription factors generated by UPR, spliced X-box binding protein1 can directly upregulated the expression of plin2, whereas C/EBP homologous protein can upregulate the expression of plin2 through peroxisome proliferator activated-receptor α. These results revealed that the LD protein PLIN2 played an important role in ER stress-induced hepatic steatosis, which might be a novel mechanism explaining hepatic steatosis triggered by ER stress.

Factors affecting the quality of therapeutic proteins in recombinant Chinese hamster ovary cell culture

Chinese hamster ovary (CHO) cells are the most widely used mammalian host cells for the commercial production of therapeutic proteins. Fed-batch culture is widely used to produce therapeutic proteins, including monoclonal antibodies, because of its operational simplicity and high product titer. Despite technical advances in the development of culture media and cell cultures, it is still challenging to maintain high productivity in fed-batch cultures while also ensuring good product quality. In this review, factors that affect the quality attributes of therapeutic proteins in recombinant CHO (rCHO) cell culture, such as glycosylation, charge variation, aggregation, and degradation, are summarized and categorized into three groups: culture environments, chemical additives, and host cell proteins accumulated in culture supernatants. Understanding the factors that influence the therapeutic protein quality in rCHO cell culture will facilitate the development of large-scale, high-yield fed-batch culture processes for the production of high-quality therapeutic proteins.

β-Caryophyllene may attenuate hyperoxaluria-induced kidney dysfunction in rats by regulating stress marker KIM-1/MCP-1 and NF-κB signaling pathway

β-Caryophyllene (BCP), a bicyclic sesquiterpene, has proved to exhibit antioxidant and anti-inflammatory activities. The present study is carried out to investigate BCP impact on hyperoxaluria-induced kidney dysfunction in male Wistar rats. The animals were categorized into four groups, namely, Group I, control rats; Group II, ethylene glycol (inducer); Group III, inducer + BCP (100 µM/kg bw); Group IV, BCP alone. After the treatment period, the rate of creatinine clearance and the concentration of urea in urine and serum were assessed. Histopathology reports were conducted to study renal and liver tissues, while the reverse transcription-polymerase chain reaction studies were carried out for messenger RNA expression of inflammatory (nuclear factor kappa B) and endoplasmic reticulum (ER) stress (kidney dysfunction molecule-1, monocyte chemoattractant protein-1, glucose binding protein 78, CHOP, activating factor 4, and X-box binding protein-1) markers as well as antioxidant activity for the hyperoxaluric rats. Western blot was performed to investigate the level of protein expression by the treatment group on apoptotic (Bcl-2, Bax, caspase-3, and caspase-9) proteins. The results show BCP to possess a renoprotective effect under hyperoxaluric conditions by decreasing the level of the inflammatory and ER stress markers and restoring the enzymes' antioxidant activities. The histology reports depicted the satisfactory morphology of glomerulus in diseased rats. Furthermore, the results of Western blot suggested that BCP may possess inhibitory action on apoptosis by affecting the mitochondrial-dependent apoptotic pathway. Therefore, BCP can be considered as a potential candidate for the therapy of hyperoxaluric-induced kidney complications.

Mechanism of Endoplasmic Reticulum Stress in Cerebral Ischemia

Endoplasmic reticulum (ER) is the main organelle for protein synthesis, trafficking and maintaining intracellular Ca²⁺ homeostasis. The stress response of ER results from the disruption of ER homeostasis in neurological disorders. Among these disorders, cerebral ischemia is a prevalent reason of death and disability in the world. ER stress stemed from ischemic injury initiates unfolded protein response (UPR) regarded as a protection mechanism. Important, disruption of Ca²⁺ homeostasis resulted from cytosolic Ca²⁺ overload and depletion of Ca²⁺ in the lumen of the ER could be a trigger of ER stress and the misfolded protein synthesis. Brain cells including neurons, glial cells and endothelial cells are involved in the complex pathophysiology of ischemic stroke. This is generally important for protein underfolding, but even more for cytosolic Ca²⁺ overload. Mild ER stress promotes cells to break away from danger signals and enter the adaptive procedure with the activation of pro-survival mechanism to rescue ischemic injury, while chronic ER stress generally serves as a detrimental role on nerve cells via triggering diverse pro-apoptotic mechanism. What’s more, the determination of some proteins in UPR during cerebral ischemia to cell fate may have two diametrically opposed results which involves in a specialized set of inflammatory and apoptotic signaling pathways. A reasonable understanding and exploration of the underlying molecular mechanism related to ER stress and cerebral ischemia is a prerequisite for a major breakthrough in stroke treatment in the future. This review focuses on recent findings of the ER stress as well as the progress research of mechanism in ischemic stroke prognosis provide a new treatment idea for recovery of cerebral ischemia.

Investigating Optimal Autologous Cellular Platforms for Prenatal or Perinatal Factor VIII Delivery to Treat Hemophilia A

Patients with the severe form of hemophilia A (HA) present with a severe phenotype, and can suffer from life-threatening, spontaneous hemorrhaging. While prophylactic FVIII infusions have revolutionized the clinical management of HA, this treatment is short-lived, expensive, and it is not available to many A patients worldwide. In the present study, we evaluated a panel of readily available cell types for their suitability as cellular vehicles to deliver long-lasting FVIII replacement following transduction with a retroviral vector encoding a B domain-deleted human F8 transgene. Given the immune hurdles that currently plague factor replacement therapy, we focused our investigation on cell types that we deemed to be most relevant to either prenatal or very early postnatal treatment and that could, ideally, be autologously derived. Our findings identify several promising candidates for use as cell-based FVIII delivery vehicles and lay the groundwork for future mechanistic studies to delineate bottlenecks to efficient production and secretion of FVIII following genetic-modification.

Mutation in FBXO32 causes dilated cardiomyopathy through up-regulation of ER-stress mediated apoptosis

Endoplasmic reticulum (ER) stress induction of cell death is implicated in cardiovascular diseases. Sustained activation of ER-stress induces the unfolded protein response (UPR) pathways, which in turn activate three major effector proteins. We previously reported a missense homozygous mutation in FBXO32 (MAFbx, Atrogin-1) causing advanced heart failure by impairing autophagy. In the present study, we performed transcriptional profiling and biochemical assays, which unexpectedly revealed a reduced activation of UPR effectors in patient mutant hearts, while a strong up-regulation of the CHOP transcription factor and of its target genes are observed. Expression of mutant FBXO32 in cells is sufficient to induce CHOP-associated apoptosis, to increase the ATF2 transcription factor and to impair ATF2 ubiquitination. ATF2 protein interacts with FBXO32 in the human heart and its expression is especially high in FBXO32 mutant hearts. These findings provide a new underlying mechanism for FBXO32-mediated cardiomyopathy, implicating abnormal activation of CHOP. These results suggest alternative non-canonical pathways of CHOP activation that could be considered to develop new therapeutic targets for the treatment of FBXO32-associated DCM.

Al-Yacoub et al. investigate the consequences of FBXO32 mutation on dilated cardiomyopathy. ER stress, abnormal CHOP activation and CHOP-induced apoptosis with no UPR effector activation are found to underlie the FBXO32 mutation induced cardiomyopathy, suggesting an alternative pathway that can be considered to develop new therapeutic targets for its treatment.

The Yeast eIF2 Kinase Gcn2 Facilitates H2O2-Mediated Feedback Inhibition of Both Protein Synthesis and Endoplasmic Reticulum Oxidative Folding during Recombinant Protein Production

Recombinant protein production is a known source of oxidative stress. However, knowledge of which reactive oxygen species are involved or the specific growth phase in which stress occurs remains lacking. Using modern, hypersensitive genetic H₂O₂-specific probes, microcultivation, and continuous measurements in batch culture, we observed H₂O₂ accumulation during and following the diauxic shift in engineered Saccharomyces cerevisiae, correlating with peak α-amylase production. In agreement with previous studies supporting a role of the translation initiation factor kinase Gcn2 in the response to H₂O₂, we find that Gcn2-dependent phosphorylation of eIF2α increases alongside translational attenuation in strains engineered to produce large amounts of α-amylase. Gcn2 removal significantly improved α-amylase production in two previously optimized high-producing strains but not in the wild type. Gcn2 deficiency furthermore reduced intracellular H₂O₂ levels and the Hac1 splicing ratio, while expression of antioxidants and the endoplasmic reticulum (ER) disulfide isomerase PDI1 increased. These results suggest protein synthesis and ER oxidative folding are coupled and subject to feedback inhibition by H₂O₂.

IMPORTANCE Recombinant protein production is a multibillion dollar industry. Optimizing the productivity of host cells is, therefore, of great interest. In several hosts, oxidants are produced as an unwanted side product of recombinant protein production. The buildup of oxidants can result in intracellular stress responses that could compromise the productivity of the host cell. Here, we document a novel protein synthesis inhibitory mechanism that is activated by the buildup of a specific oxidant (H₂O₂) in the cytosol of yeast cells upon the production of recombinant proteins. At the center of this inhibitory mechanism lies the protein kinase Gcn2. By removing Gcn2, we observed a doubling of recombinant protein productivity in addition to reduced H₂O₂ levels in the cytosol. In this study, we want to raise awareness of this inhibitory mechanism in eukaryotic cells to further improve protein production and contribute to the development of novel protein-based therapeutic strategies.

Can a Micronutrient Mixture Delay the Onset and Progression of Symptoms of Single-Point Mutation Diseases?

Single-point mutation diseases in which substitution of one nucleotide with another in a gene occurs include familial Alzheimer's disease (fAD), familial Parkinson's disease (fPD), and familial Creutzfeldt-Jacob disease (fCJD) as well as Huntington's disease (HD), sickle cell anemia, and hemophilia. Inevitability of occurrence of these diseases is certain. However, the time of appearance of symptoms could be influenced by the diet, environment, and possibly other genetic factors. There are no effective approaches to delay the onset or progression of symptoms of these diseases. The fact that increased oxidative stress and inflammation significantly contribute to the initiation and progression of these point mutation diseases shows that antioxidants could be useful. The major objectives are (a) to present evidence that increased oxidative stress and chronic inflammation are associated with selected single-point mutation diseases, such as fAD, fPD, and fCJD, HD, sickle cell anemia, and hemophilia; (b) to describe limited studies on the role of individual antioxidants in experimental models of some of these diseases; and (c) to discuss a rationale for utilizing a comprehensive mixture of micronutrients, which may delay the development and progression of symptoms of above diseases by simultaneously reducing oxidative and inflammatory damages.Key teaching pointsSelected single-point mutation diseases and their pattern of inheritanceCharacteristics of each selected single-point mutation diseaseEvidence for increased oxidative stress and inflammation in each diseasePotential reasons for failure of single antioxidants in human studiesRationale for using a comprehensive mixture of micronutrients in delaying the onset and progression of single-point mutation diseases.

Gallic Acid Prevents the Oxidative and Endoplasmic Reticulum Stresses in the Hippocampus of Adult-Onset Hypothyroid Rats

Thyroid hormone is essential for hippocampal redox environment and neuronal viability in adulthood, where its deficiency causes hypothyroidism related to oxidative and endoplasmic reticulum stresses in the hippocampus, resulting in neuronal death. One option of treatment is antioxidants; however, they must be transported across the blood-brain barrier. Gallic acid is a polyphenol that meets these criteria. Thus, this study aimed to prove that the neuroprotective mechanism of GA is associated with the prevention of oxidative and endoplasmic reticulum stresses in the hippocampus of adult-onset hypothyroid rats. Male Wistar rats were divided into euthyroid (n = 20) and hypothyroid groups (n = 20). Thyroidectomy with parathyroid gland reimplementation caused hypothyroidism. Each group was subdivided into two: vehicle and 50 mg/kg/d of gallic acid. 3 weeks after thyroidectomy, six animals of each group were euthanized, and the hippocampus was dissected to evaluate oxidative and endoplasmic reticulum stress markers. The rest of the animals were euthanized after 4 weeks of treatment for histological analysis of the hippocampus. The results showed that hypothyroidism increased lipid peroxidation, reactive oxygen species, and nitrites; it also increased endoplasmic reticulum stress by activating the inositol-requiring enzyme-1α (IRE1α) pathway, the protein kinase RNA-like endoplasmic reticulum kinase (PERK) and activated transcription factor 6α (ATF6α) pathways associated with a proapoptotic state that culminates in hippocampal neuronal damage. Meanwhile, the hypothyroid rat treated with gallic acid reduced oxidative stress and increased endoplasmic reticulum-associated degradation (ERAD) through IRE1α and ATF6. Also, the gallic acid treatment prevented the Bax/BCl2 ratio from increasing and the overexpression of p53 and caspase 12. This treatment in hypothyroid animals was associated with the neuronal protection observed in the hippocampus. In conclusion, gallic acid prevents hypothyroidism-induced hippocampal damage associated with oxidative and endoplasmic reticulum stresses.

C/EBP homologous protein deficiency enhances hematopoietic stem cell function via reducing ATF3/ROS-induced cell apoptosis

Hematopoietic stem cells (HSCs) reside in a quiescent niche to reserve their capacity of self‐renewal. Upon hematopoietic injuries, HSCs enter the cell cycle and encounter protein homeostasis problems caused by accumulation of misfolded proteins. However, the mechanism by which protein homeostasis influences HSC function and maintenance remains poorly understood. Here, we show that C/EBP homologous protein (CHOP), demonstrated previously to induces cell death upon unfolded protein response (UPR), plays an important role in HSCs regeneration. CHOP^−/− mice showed normal hematopoietic stem and progenitor cell frequencies in steady state. However, when treated with 5‐FU, CHOP deficiency resulted in higher survival rates, associated with an increased number of HSCs and reduced level of apoptosis. In serial competitive transplantation experiments, CHOP^−/− HSCs showed a dramatic enhancement of repopulation ability and a reduction of protein aggresomes. Mechanistically, CHOP deletion causes reduced ATF3 expression and further leads to decreased protein aggregation and ROS. In addition, CHOP^−/− HSCs exhibited an increased resistance to IR‐induced DNA damage and improved HSCs homeostasis and function in telomere dysfunctional (G3Terc^−/−) mice. In summary, these findings disclose a new role of CHOP in the regulation of the HSCs function and homeostasis through reducing ATF3 and ROS signaling.

Upregulation of V-ATPase by STAT3 Activation Promotes Anoikis Resistance and Tumor Metastasis

Most cancer mortality results from metastatic tumor cells and not the localized tumor. Overcoming anoikis is one of the most important steps for detached tumor cells to migrate and metastasize. However, the molecular mechanisms remain to be fully deciphered. Herein, our study revealed upregulation of vacuolar ATPase (V-ATPase) in cancer cells during ECM detachment plays a key role in anoikis evasion. V-ATPase is an enzyme complex that utilizes energy from ATP hydrolysis to maintain cellular homeostasis and had been reported to enhance cancer progression. In this study, V-ATPase inhibition sensitized human cervical cancer, breast cancer, and murine melanoma cells to anoikis via increased ROS production, accumulation of misfolded protein, and impaired pulmonary metastasis in vivo. Scavenging ROS restored anoikis resistance and clearance of misfolded protein accumulation in the tumor cells. Mechanistically, STAT3 upregulates V-ATPase expression while blockade of STAT3 activity repressed V-ATPase expression in these tumor cells as well as sensitized cells to anoikis, increased ROS production, and misfolded protein accumulation. Altogether, our data demonstrate an unreported role of STAT3 in mediating the upregulation of V-ATPase to promote anoikis resistance, thus provides an alternative option to target cancer metastasis.

Effect of Reactive Oxygen Species on the Endoplasmic Reticulum and Mitochondria during Intracellular Pathogen Infection of Mammalian Cells

Oxidative stress, particularly reactive oxygen species (ROS), are important for innate immunity against pathogens. ROS directly attack pathogens, regulate and amplify immune signals, induce autophagy and activate inflammation. In addition, production of ROS by pathogens affects the endoplasmic reticulum (ER) and mitochondria, leading to cell death. However, it is unclear how ROS regulate host defense mechanisms. This review outlines the role of ROS during intracellular pathogen infection, mechanisms of ROS production and regulation of host defense mechanisms by ROS. Finally, the interaction between microbial pathogen-induced ROS and the ER and mitochondria is described.

Endoplasmic reticulum stress promotes epithelial‑mesenchymal transition via the PERK signaling pathway in paraquat‑induced pulmonary fibrosis

Pulmonary fibrosis is the primary reason for mortality in patients with paraquat (PQ) poisoning. Our previous study demonstrated that epithelial-mesenchymal transition (EMT) had a role in PQ-induced pulmonary fibrosis. However, the role of endoplasmic reticulum (ER) stress in PQ-induced EMT remains clear. The present study aimed to determine the role of ER stress in EMT in PQ-induced pulmonary fibrosis. A549 and RLE-6TN cells were incubated with LY294002 (a PI3K inhibitor) or transfected with protein kinase RNA-like ER kinase (PERK) small interfering RNA (si) for 24 h prior to being exposed to PQ. Next, the expression levels of ER stress-related proteins, PI3K/AKT/GSK-3β signaling pathway-related proteins and EMT-related markers were analyzed by performing western blotting, reverse transcription-quantitative PCR and immunofluorescence assays. The results of the present study revealed that the protein expression levels of PERK, phosphorylated (p)-PERK, p-eukaryotic initiation factor 2 (eIF2)α were significantly upregulated in the PQ group, whereas p-PI3K, p-AKT and p-GSK-3β were significantly upregulated in the sicontrol + PQ group compared with the sicontrol group. In vitro, following transfection with siPERK or treatment with the PI3K inhibitor, the protein expression levels of E-cadherin (an epithelial marker) were upregulated, whereas the protein expression levels of α-SMA (a mesenchymal marker) were downregulated. Immunofluorescence analysis revealed that the levels of E-cadherin were markedly upregulated, whereas the levels of α-SMA were notably downregulated following transfection with siPERK compared with the sicontrol group. The results of wound healing assay demonstrated that cell migration in the siPERK + PQ group was markedly decreased compared with the sicontrol + PQ group. These indicated that PQ-induced EMT was suppressed after silencing PERK. The expression levels of p-GSK-3β, p-AKT and p-PI3K were also markedly downregulated in the siPERK + PQ group compared with the sicontrol + PQ group. In conclusion, the findings of the present study suggested that ER stress may promote EMT through the PERK signaling pathway in PQ-induced pulmonary fibrosis. Thus, ER stress may represent a potential therapeutic target for PQ-induced pulmonary fibrosis.

Redox and Inflammatory Signaling, the Unfolded Protein Response, and the Pathogenesis of Pulmonary Hypertension

Protein folding overload and oxidative stress disrupt endoplasmic reticulum (ER) homeostasis, generating reactive oxygen species (ROS) and activating the unfolded protein response (UPR). The altered ER redox state induces further ROS production through UPR signaling that balances the cell fates of survival and apoptosis, contributing to pulmonary microvascular inflammation and dysfunction and driving the development of pulmonary hypertension (PH). UPR-induced ROS production through ER calcium release along with NADPH oxidase activity results in endothelial injury and smooth muscle cell (SMC) proliferation. ROS and calcium signaling also promote endothelial nitric oxide (NO) synthase (eNOS) uncoupling, decreasing NO production and increasing vascular resistance through persistent vasoconstriction and SMC proliferation. C/EBP-homologous protein further inhibits eNOS, interfering with endothelial function. UPR-induced NF-κB activity regulates inflammatory processes in lung tissue and contributes to pulmonary vascular remodeling. Conversely, UPR-activated nuclear factor erythroid 2-related factor 2-mediated antioxidant signaling through heme oxygenase 1 attenuates inflammatory cytokine levels and protects against vascular SMC proliferation. A mutation in the bone morphogenic protein type 2 receptor (BMPR2) gene causes misfolded BMPR2 protein accumulation in the ER, implicating the UPR in familial pulmonary arterial hypertension pathogenesis. Altogether, there is substantial evidence that redox and inflammatory signaling associated with UPR activation is critical in PH pathogenesis.

NRF2-mediated signaling is a master regulator of transcription factors in bovine granulosa cells under oxidative stress condition

Transcription factors (TFs) are known to be involved in regulating the expression of several classes of genes during folliculogenesis. However, the regulatory role of TFs during oxidative stress (OS) is not fully understood. The current study was aimed to investigate the regulation of the TFs in bovine granulosa cells (bGCs) during exposure to OS induced by H₂O₂ in vitro. For this, bGCs derived from ovarian follicles were cultured in vitro till their confluency and then treated with H₂O₂ for 40 min. Twenty-four hours later, cells were subjected to various phenotypic and gene expression analyses for genes related to TFs, endoplasmic reticulum stress, apoptosis, cell proliferation, and differentiation markers. The bGCs exhibited higher reactive oxygen species accumulation, DNA fragmentation, and endoplasmic reticulum stress accompanied by reduction of mitochondrial activity after exposure to OS. In addition, higher lipid accumulation and lower cell proliferation were noticed in H₂O₂-challenged cells. The mRNA level of TFs including NRF2, E2F1, KLF6, KLF9, FOS, SREBF1, SREBF2, and NOTCH1 was increased in H₂O₂-treated cells compared with non-treated controls. However, the expression level of KLF4 and its downstream gene, CCNB1, were downregulated in the H₂O₂-challenged group. Moreover, targeted inhibition of NRF2 using small interference RNA resulted in reduced expression of KLF9, FOS, SREBF2, and NOTCH1 genes, while the expression of KLF4 was upregulated. Taken together, bovine granulosa cells exposed to OS exhibited differential expression of various transcription factors, which are mediated by the NRF2 signaling pathway.