Targeting unfolded protein response: a new horizon for disease control

Activation of PERK/eIF2α/ATF4 signaling inhibits ERα expression in breast cancer

Approximately 70-80% of breast cancers rely on estrogen receptor alpha (ERα) for growth. The unfolded protein response (UPR), a cellular response to endoplasmic reticulum stress (ERS), is an important process crucial for oncogenic transformation. The effect of ERS on ERα expression and signaling remains incompletely elucidated. Here, we focused on the regulatory mechanisms of ERS on ERα expression in ER-positive breast cancer (ER+ BC). Our results demonstrate that ERα protein and mRNA levels in ER+ BC cells are considerably reduced by the ERS inducers thapsigargin (TG) and brefeldin A (BFA) via the PERK/eIF2α/ATF4 signaling pathway. ChIP-qPCR and luciferase reporter gene analysis revealed that ERS induction facilitated ATF4 binding to the ESR1 (the gene encoding ERα) promoter region, thereby suppressing ESR1 promoter activity and inhibiting ERα expression. Furthermore, selective activation of PERK signaling or ATF4 overexpression attenuated ERα expression and tumor cell growth both in vitro and in vivo. In conclusion, our results demonstrate that ERS suppresses ERα expression transcriptionally via the PERK/eIF2α/ATF4 signaling. Our study provides insights into the treatment of ER+ BC by targeting ERα signaling through selective activation of the PERK branch of the UPR.

Redox regulation of lung endothelial PERK, unfolded protein response (UPR) and proliferation via NOX1: Targeted inhibition as a potential therapy for PAH

AIMS

Reactive oxygen species (ROS) play an important role in the pathogenesis of pulmonary arterial hypertension (PAH) and NADPH oxidases (NOXs) as sources of ROS are implicated in the development of the disease. We previously showed that NOX isozyme 1 (NOX1)-derived ROS contributes to pulmonary vascular endothelial cell (EC) proliferation in response to PAH triggers in vitro. However, whether and how NOX1 is involved in PAH in vivo have not been explored nor has NOX1 been examined as a viable and effective therapeutic disease target.

METHODS AND RESULTS

Herein, infusion of mice exposed to Sugen/hypoxia (10 % O2) with a specific NOX1 inhibitor, NOXA1ds, delivered via osmotic minipumps (i.p.), significantly suppressed pathological changes in hemodynamic parameters characteristic of PAH. Furthermore, lungs of human patients with idiopathic PAH (iPAH) and exploratory RNA-seq analysis of hypoxic human pulmonary ECs, in which NOX1 was suppressed, were probed. The findings showed a clear indication of NOX1 in the promotion of both protein disulfide isomerase (PDI) and the unfolded protein response (UPR; in particular, the PERK arm of the pathway including eIF2α and ATF4) leading to proliferation. In aggregate, these results are consistent with a causal role for NOX1 in the development of mouse and human PAH and reveal a novel and mechanistic pathway by which NOX1 activates the UPR response during EC proliferation.

CONCLUSION

NOX1 promotes phenotypic changes in ECs that are pivotal to proliferation and PAH through activation of the UPR. Taken together, our results are consistent with selective inhibition of NOX1 as a novel modality for attenuating PAH.

Enhancing antitumor immunity: the role of immune checkpoint inhibitors, anti-angiogenic therapy, and macrophage reprogramming

Cancer treatment has long been hindered by the complexity of the tumor microenvironment (TME) and the mechanisms that tumors employ to evade immune detection. Recently, the combination of immune checkpoint inhibitors (ICIs) and anti-angiogenic therapies has emerged as a promising approach to improve cancer treatment outcomes. This review delves into the role of immunostimulatory molecules and ICIs in enhancing anti-tumor immunity, while also discussing the therapeutic potential of anti-angiogenic strategies in cancer. In particular, we highlight the critical role of endoplasmic reticulum (ER) stress in angiogenesis. Moreover, we explore the potential of macrophage reprogramming to bolster anti-tumor immunity, with a focus on restoring macrophage phagocytic function, modulating hypoxic tumor environments, and targeting cytokines and chemokines that shape immune responses. By examining the underlying mechanisms of combining ICIs with anti-angiogenic therapies, we also review recent clinical trials and discuss the potential of biomarkers to guide and predict treatment efficacy.

Spring viraemia of carp virus modulates the time-dependent unfolded protein response to facilitate viral replication

Introduction

The spring viraemia of carp virus (SVCV) poses a significant threat to global aquaculture, yet effective antiviral drugs and vaccines remain unavailable. Understanding the interplay between host-pathogen interactions and SVCV replication is crucial for devising preventive strategies.

Methods

ZF4 cells were exposed to UV-inactivated SVCV or live SVCV at different multiplicities of infection, and the modulation of the unfolded protein response (UPR) was assayed by qPCR at different times. Moreover, ZF4 cells were treated with several UPR modulators to investigate their effect on viral replication. The UPR was also modulated in vivo in zebrafish larvae, and its impact on the survival against SVCV infection was evaluated.

Results and conclusions

This study reveals how SVCV exploits the host's UPR to facilitate its replication. SVCV targets the immunoglobulin heavy chain-binding protein (BiP) and the activating transcription factor 4 (ATF4) during early infection to enhance viral RNA synthesis and translation. At later stages, activation of the BiP, the PKR-like ER kinase (PERK), and the inositol-requiring enzyme 1 alpha (IRE1α) pathways supports the release of viral progeny and induces cellular processes, including immune responses and apoptotic cell death. Furthermore, the data demonstrate that modulating UPR pathways, particularly ATF6 and PERK, significantly affect viral replication, providing a novel avenue for antiviral drug development. Preliminary in vivo studies suggest the feasibility of chemically modulating the UPR to combat SVCV, though optimizing administration conditions to maximize efficacy while minimizing side effects warrants further investigation. These findings offer critical insights into the molecular mechanisms underlying SVCV pathogenesis and highlight promising targets for therapeutic intervention.

Advances in Studying the Pathologic Mechanisms and Treatment Strategies of Transthyretin Amyloidosis

ABSTRACT

Transthyretin amyloidosis (ATTR) is characterized by the deposition of unstable transthyretin protein (TTR) in the heart or peripheral nerves. Therapeutic strategies for ATTR include inhibition of the secretion of abnormal TTR by the liver, reducing the concentration of aberrant TTR in the circulation, and eliminating amyloid deposits of TTR in tissues. This article delves into the pathogenesis of TTR secretion from the liver into the bloodstream, its deposition in tissues, and the subsequent development of ATTR. In addition, we delineated the advancements in treatment strategies and discussed future research directions to provide novel insights for the identification of diagnostic and preventive targets.

Endothelial Unfolded Protein Response-Mediated Cytoskeletal Effects

The endothelial semipermeable monolayers ensure tissue homeostasis, are subjected to a plethora of stimuli, and their function depends on cytoskeletal integrity and remodeling. The permeability of those membranes can fluctuate to maintain organ homeostasis. In cases of severe injury, inflammation or disease, barrier hyperpermeability can cause irreparable damage of endothelium-dependent issues, and eventually death. Elucidation of the signaling regulating cytoskeletal structure and barrier integrity promotes the development of targeted pharmacotherapies towards disorders related to the impaired endothelium (e.g., acute respiratory distress syndrome, sepsis). Recent reports investigate the role of unfolded protein response in barrier function. Herein we review the cytoskeletal components, the unfolded protein response function; and their interrelations on health and disorder. Moreover, we emphasize on unfolded protein response modulators, since they ameliorate illness related to endothelial leak.

Renal tubular epithelial cell quality control mechanisms as therapeutic targets in renal fibrosis

Renal fibrosis is a devastating consequence of progressive chronic kidney disease, representing a major public health challenge worldwide. The underlying mechanisms in the pathogenesis of renal fibrosis remain unclear, and effective treatments are still lacking. Renal tubular epithelial cells (RTECs) maintain kidney function, and their dysfunction has emerged as a critical contributor to renal fibrosis. Cellular quality control comprises several components, including telomere homeostasis, ubiquitin-proteasome system (UPS), autophagy, mitochondrial homeostasis (mitophagy and mitochondrial metabolism), endoplasmic reticulum (ER, unfolded protein response), and lysosomes. Failures in the cellular quality control of RTECs, including DNA, protein, and organelle damage, exert profibrotic functions by leading to senescence, defective autophagy, ER stress, mitochondrial and lysosomal dysfunction, apoptosis, fibroblast activation, and immune cell recruitment. In this review, we summarize recent advances in understanding the role of quality control components and intercellular crosstalk networks in RTECs, within the context of renal fibrosis.

Insights into the Activation of Unfolded Protein Response Mechanism during Coronavirus Infection

Coronaviruses represent a significant class of viruses that affect both animals and humans. Their replication cycle is strongly associated with the endoplasmic reticulum (ER), which, upon virus invasion, triggers ER stress responses. The activation of the unfolded protein response (UPR) within infected cells is performed from three transmembrane receptors, IRE1, PERK, and ATF6, and results in a reduction in protein production, a boost in the ER's ability to fold proteins properly, and the initiation of ER-associated degradation (ERAD) to remove misfolded or unfolded proteins. However, in cases of prolonged and severe ER stress, the UPR can also instigate apoptotic cell death and inflammation. Herein, we discuss the ER-triggered host responses after coronavirus infection, as well as the pharmaceutical targeting of the UPR as a potential antiviral strategy.

Naturally occurring small molecules with dual effect upon inflammatory signaling pathways and endoplasmic reticulum stress response

The endoplasmic reticulum (ER) is determinant to maintain cellular proteostasis. Upon unresolved ER stress, this organelle activates the unfolded protein response (UPR). Sustained UPR activates is known to occur in inflammatory processes, deeming the ER a potential molecular target for the treatment of inflammation. This work characterizes the inflammatory/UPR-related molecular machinery modulated by an in-house library of natural products, aiming to pave the way for the development of new selective drugs that act upon the ER to counter inflammation-related chronic diseases. Starting from a library of 134 compounds of natural occurrence, mostly occurring in medicinal plants, nontoxic molecules were screened for their inhibitory capacity against LPS-induced nuclear factor kappa B (NF-κB) activation in a luciferase-based reporter gene assay. Since several natural products inhibited NF-κB expression in THP-1 macrophages, their effect on reactive oxygen species (ROS) production and inflammasome activation was assessed, as well as their transcriptional outcome regarding ER stress. The bioactivities of several natural products are described herein for the first time. We report the anti-inflammatory potential of guaiazulene and describe 5-deoxykaempferol as a novel inhibitor of inflammasome activation. Furthermore, we describe the dual potential of 5-deoxykaempferol, berberine, guaiazulene, luteolin-4'-O-glucoside, myricetin, quercetagetin and sennoside B to modulate inflammatory signaling ER stress. Our results show that natural products are promising molecules for the discovery and pharmaceutical development of chemical entities able to modulate the inflammatory response, as well as proteostasis and the UPR.

Mechanism of Decision Making between Autophagy and Apoptosis Induction upon Endoplasmic Reticulum Stress

Dynamic regulation of the cellular proteome is mainly controlled in the endoplasmic reticulum (ER). Accumulation of misfolded proteins due to ER stress leads to the activation of unfolded protein response (UPR). The primary role of UPR is to reduce the bulk of damages and try to drive back the system to the former or a new homeostatic state by autophagy, while an excessive level of stress results in apoptosis. It has already been proven that the proper order and characteristic features of both surviving and self-killing mechanisms are controlled by negative and positive feedback loops, respectively. The new results suggest that these feedback loops are found not only within but also between branches of the UPR, fine-tuning the response to ER stress. In this review, we summarize the recent knowledge of the dynamical characteristic of endoplasmic reticulum stress response mechanism by using both theoretical and molecular biological techniques. In addition, this review pays special attention to describing the mechanism of action of the dynamical features of the feedback loops controlling cellular life-and-death decision upon ER stress. Since ER stress appears in diseases that are common worldwide, a more detailed understanding of the behaviour of the stress response is of medical importance.

Inhibition of endoplasmic reticulum stress restores the balance of renal RAS components and lowers blood pressure in the spontaneously hypertensive rats

BACKGROUND

Endoplasmic reticulum (ER) stress has been shown to play a critical role in the pathogenesis of hypertension. However, the underlying mechanisms for lowering blood pressure (BP) by suppressing ER stress remain unclear. Here, we hypothesized that inhibition of ER stress could restore the balance between RAS components and lower BP in spontaneously hypertensive rats (SHRs).

METHODS

Wistar-Kyoto (WKY) rats and SHRs received vehicle or 4-PBA, an ER stress inhibitor, in the drinking water for 4 weeks. BP was measured by tail-cuff plethysmography, and the expression of RAS components was examined by Western blot.

RESULTS

Compared with vehicle-treated WKY rats, vehicle-treated SHRs exhibited higher blood pressure and increased renal ER stress and oxidative stress, accompanied by impaired diuresis and natriuresis. Moreover, SHRs had higher ACE and AT₁R and lower AT₂R, ACE2, and MasR expressions in the kidney. Interestingly, 4-PBA treatment improved impaired diuresis and natriuresis and lowered blood pressure in SHRs, accompanied by reducing ACE and AT₁R protein expression and increasing AT₂R, ACE2, and MasR expression in the kidneys of SHRs. In addition, these changes were associated with the reduction of ER stress and oxidative stress.

CONCLUSIONS

These results suggest that the imbalance of renal RAS components was associated with increased ER stress in SHRs. Inhibition of ER stress with 4-PBA reversed the imbalance of renal RAS components and restored the impaired diuresis and natriuresis, which, at least in part, explains the blood pressure-lowering effects of 4-PBA in hypertension.

The ameliorative effect of CangFu Daotan Decoction on polycystic ovary syndrome of rodent model is associated with m6A methylation and Wnt/β-catenin pathway

Objective: This study investigates the effects of CangFu Daotan Decoction (CDD) on m6A methylation and Wnt/β-catenin pathway in rats with polycystic ovary syndrome (PCOS).Methods: The PCOS rat model was established by letrozole gavage. The rats were fed high-fat chow, and their body weight and blood glucose were recorded. The expressions of follicle-stimulating hormone(FSH), luteinizing hormone(LH), and testosterone(T) were quantified by ELISA. Chemical components in CDD were analyzed using UPLC-Q/TOF-MS. Based on network pharmacology methods, related targets of CDD on PCOS were screened. An enrichment analysis according to Tokyo Encyclopedia of Genes and Genomes (KEGG) was conducted to predict the potential signaling pathway of CDD in PCOS. The expressions of Wnt-1, β-Catenin, GSK-3β, C-MYC, Beclin1, LC3II, Bax, and PCNA were detected by western blotting. The expressions of Mettl3, Mettl14, Fto, Alkbh5, Ythdf1, and Ythdf2 were monitored by RT-PCR. The expressions of Mettl3, Fto, and Ythdf1 were detected by western blotting.Results: Letrozole and a high-fat diet induced ovarian dysfunction in rats, which was attenuated by CDD. CDD decreased blood glucose, LH, and T concentrations and increased FSH expression in PCOS. After removing duplicates, a total of 71 compounds were identified by UHPLC-Q/TOF-MS, among which terpenoids and flavonoids account for the main proportion. The clustering analysis showed that the active site of CDD might be in the Wnt/β-catenin pathway. CDD decreased the expressions of Wnt-1, β-Catenin, GSK-3β, C-MYC, Beclin1, LC3II, and Bax and increased PCNA expression in the ovarian tissue of PCOS rats. CDD decreased the m6A gene expressions of Mettl3, Mettl14, Fto, Alkbh5, Ythdf1, and Ythdf2 in peripheral blood and ovarian tissue of PCOS rats. CDD reduced the m6A proteins expressions of Mettl3, Fto, and Ythdf1 in the ovarian tissue of PCOS rats.Conclusion: CDD can regulate m6A modification and inhibit the Wnt/β-catenin signaling pathway in PCOS rats, thereby reducing body weight, lowering blood glucose levels, improving sex hormone disorders, and decreasing autophagy and apoptosis in ovarian tissue to promote the recovery of ovarian morphology.

ER-phagy in neurodegeneration

There are many cellular mechanisms implicated in the initiation and progression of neurodegenerative disorders. However, age and the accumulation of unwanted cellular products are a common theme underlying many neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, and Niemann-Pick type C. Autophagy has been studied extensively in these diseases and various genetic risk factors have implicated disruption in autophagy homoeostasis as a major pathogenic mechanism. Autophagy is essential in the maintenance of neuronal homeostasis, as their postmitotic nature makes them particularly susceptible to the damage caused by accumulation of defective or misfolded proteins, disease-prone aggregates, and damaged organelles. Recently, autophagy of the endoplasmic reticulum (ER-phagy) has been identified as a novel cellular mechanism for regulating ER morphology and response to cellular stress. As neurodegenerative diseases are generally precipitated by cellular stressors such as protein accumulation and environmental toxin exposure the role of ER-phagy has begun to be investigated. In this review we discuss the current research in ER-phagy and its involvement in neurodegenerative diseases.

Cadmium-induced pyroptosis is mediated by PERK/TXNIP/NLRP3 signaling in SH-SY5Y cells

Cadmium (Cd) is a hypertoxic heavy metal that may be exposed to environmental pollutants by humans and animals. It can lead to cognitive disfunction, and is linked to neurodegenerative diseases. Cadmium reportedly can induce endoplasmic reticulum (ER) stress, but few studies have concentrated on it in nerve cells, and the connection between ER stress and neuroinflammation. In this study, in vitro experiments on SH-SY5Y neuroblastoma cells were carried out. We aimed at exploring whether Cd attributed to the cell pyroptosis and the role of PERK in promoting this form of cell damage which can induce strong inflammatory responses. Our results demonstrated that CdCl2 treatment induced excess reactive oxygen species (ROS) production, caused significant modifications in the expression of PERK and increased TXNIP, NLRP3, IL-1β, IL-18, and caspase1 in SH-SY5Y cells. In addition, scavenging ROS with N-acetylcysteine or inhibiting the expression of PERK by using GSK2606414, rescued the SH-SY5Y cells from cadmium-induced pyroptosis. In conclusion, the results suggest that Cd induces pyroptotic death of SH-SY5Y cells through ER stress, and this may be the potential mechanism of Cd incurring neurological diseases.

Signaling pathways and intervention for therapy of type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) represents one of the fastest growing epidemic metabolic disorders worldwide and is a strong contributor for a broad range of comorbidities, including vascular, visual, neurological, kidney, and liver diseases. Moreover, recent data suggest a mutual interplay between T2DM and Corona Virus Disease 2019 (COVID-19). T2DM is characterized by insulin resistance (IR) and pancreatic β cell dysfunction. Pioneering discoveries throughout the past few decades have established notable links between signaling pathways and T2DM pathogenesis and therapy. Importantly, a number of signaling pathways substantially control the advancement of core pathological changes in T2DM, including IR and β cell dysfunction, as well as additional pathogenic disturbances. Accordingly, an improved understanding of these signaling pathways sheds light on tractable targets and strategies for developing and repurposing critical therapies to treat T2DM and its complications. In this review, we provide a brief overview of the history of T2DM and signaling pathways, and offer a systematic update on the role and mechanism of key signaling pathways underlying the onset, development, and progression of T2DM. In this content, we also summarize current therapeutic drugs/agents associated with signaling pathways for the treatment of T2DM and its complications, and discuss some implications and directions to the future of this field.

Elnosary M, L. Ashour M, M. Abd El-Moneam N, A. Shreadah M. Flavonoids Biosynthesis in Plants as a Defense Mechanism: Role and Function Concerning Pharmacodynamics and Pharmacokinetic Properties

Flavonoids are a major class of secondary metabolites that comprises more than 6000 compounds that have been identified. They are biosynthesized via the phenylpropanoid metabolic pathway that involves groups of enzymes such as isomerases, hydroxylases, and reductases that greatly affect the determination of the flavonoid skeleton. For example, transferase enzymes responsible for the modification of sugar result in changes in the physiological activity of the flavonoids and changes in their physical properties, such as solubility, reactivity, and interaction with cellular target molecules, which affect their pharmacodynamics and pharmacokinetic properties. In addition, flavonoids have diverse biological activities such as antioxidants, anticancer, and antiviral in managing Alzheimer’s disease. However, most marine flavonoids are still incompletely discovered because marine flavonoid biosynthesis is produced and possesses unique substitutions that are not commonly found in terrestrial bioactive compounds. The current chapter will illustrate the importance of flavonoids’ role in metabolism and the main difference between marine and terrestrial flavonoids.

Unfolded protein response and angiogenesis in malignancies

Cellular stress, arising from accumulation of unfolded proteins, occurs frequently in rapidly proliferating cancer cells. This cellular stress, in turn, activates the unfolded protein response (UPR), an interconnected set of signal transduction pathways that alleviate the proteostatic stress. The UPR is implicated in cancer cell survival and proliferation through upregulation of pro-tumorigenic pathways that ultimately promote malignant metabolism and neoangiogenesis. Here, we reviewed mechanisms of signaling crosstalk between the UPR and angiogenesis pathways, as well as transmissible ER stress and the role in tumor growth and development. To characterize differences in UPR and UPR-mediated angiogenesis in malignancy, we employed a data mining approach using patient tumor data from The Cancer Genome Atlas (TCGA). The analysis of TCGA revealed differences in UPR between malignant samples versus their non-malignant counterparts.

Myeloid-Derived Suppressor Cells in Cancer and COVID-19 as Associated with Oxidative Stress

Myeloid-derived suppressor cells MDSCs are a heterogeneous population of cells that expand beyond their physiological regulation during pathologies such as cancer, inflammation, bacterial, and viral infections. Their key feature is their remarkable ability to suppress T cell and natural killer NK cell responses. Certain risk factors for severe COVID-19 disease, such as obesity and diabetes, are associated with oxidative stress. The resulting inflammation and oxidative stress can negatively impact the host. Similarly, cancer cells exhibit a sustained increase in intrinsic ROS generation that maintains the oncogenic phenotype and drives tumor progression. By disrupting endoplasmic reticulum calcium channels, intracellular ROS accumulation can disrupt protein folding and ultimately lead to proteostasis failure. In cancer and COVID-19, MDSCs consist of the same two subtypes (PMN-MSDC and M-MDSC). While the main role of polymorphonuclear MDSCs is to dampen the response of T cells and NK killer cells, they also produce reactive oxygen species ROS and reactive nitrogen species RNS. We here review the origin of MDSCs, their expansion mechanisms, and their suppressive functions in the context of cancer and COVID-19 associated with the presence of superoxide anion •O2- and reactive oxygen species ROS.

The potential role of protein disulfide isomerases (PDIs) during parasitic infections: a focus on Leishmania spp

Leishmaniasis is a group of vector-borne diseases caused by intracellular protozoan parasites belonging to the genus Leishmania. Leishmania parasites can employ different and numerous sophisticated strategies, including modulating host proteins, cell signaling, and cell responses by parasite proteins, to change the infected host conditions to favor the parasite persistence and induce pathogenesis. In this sense, protein disulfide isomerases (PDIs) have been described as crucial proteins that can be modulated during leishmaniasis and affect the pathogenesis process. The effect of modulated PDIs can be investigated in both aspects, parasite PDIs and infected host cell PDIs, during infection. The information concerning PDIs is not sufficient in parasitology; however, this study aimed to provide data regarding the biological functions of such crucial proteins in parasites with a focus on Leishmania spp. and their relevant effects on the pathogenesis process. Although there are no clinical trial vaccines and therapeutic approaches, highlighting this information might be fruitful for the development of novel strategies based on PDIs for the management of parasitic diseases, especially leishmaniasis.

Targeting RNA with small molecules-A safety perspective

RNA is a major player in cellular function, and consequently can drive a number of disease pathologies. Over the past several years, small molecule-RNA targeting (smRNA targeting) has developed into a promising drug discovery approach. Numerous techniques, tools, and assays have been developed to support this field, and significant investments have been made by pharmaceutical and biotechnology companies. To date, the focus has been on identifying disease validated primary targets for smRNA drug development, yet RNA as a secondary (off) target for all small molecule drug programs largely has been unexplored. In this perspective, we discuss structure, target, and mechanism-driven safety aspects of smRNAs and highlight how these parameters can be evaluated in drug discovery programs to produce potentially safer drugs.

Pharmacological Manipulation of UPR: Potential Antiviral Strategy Against Chikungunya Virus

Abstract

Viruses invade the host cells and maneuver the cellular translation machinery to translate the viral proteins in substantial amounts, which may disturb Endoplasmic Reticulum homeostasis leading to induction of Unfolded Protein Response (UPR), a host response pathway involved in viral pathogenesis. Here, we investigated the effect of UPR pathways on the pathogenesis of chikungunya virus infection. We observed that chikungunya virus mediated the modulation of UPR. A positive modulation was observed in the activation of IRE1 and ATF6 branch while the PERK branch of UPR observed suppressed upon virus infection. We further investigated the effect of the inhibition of UPR pathways on chikungunya virus replication using inhibitors for each branch. Cells treated with 3-ethoxy-5,6-dibromosalicylaldehyde (IRE1 inhibitor) and AEBSF (ATF6 inhibitor) significantly inhibits the viral replication process. This study has provided a novel perspective in designing antivirals against chikungunya virus.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s12088-022-01046-5.

Protein Disulfide Isomerases Function as the Missing Link Between Diabetes and Cancer

Significance: Diabetes has long been recognized as an independent risk factor for cancer, but there is insufficient mechanistic understanding of biological mediators that bridge two disorders together. Understanding the pathogenic association between diabetes and cancer has become the focus of many studies, and findings are potentially valuable for the development of effective preventive or therapeutic strategies for both disorders. Recent Advances: A summary of literature reveals a possible connection between diabetes and cancer through the family of protein disulfide isomerase (PDI). Historical as well as the most recent findings on the structure, biochemistry, and biology of the PDI family were summarized in this review. Critical Issues: PDIs in general function as redox enzymes and protein chaperones to control the quality of proteins by correcting or otherwise eliminating misfolded proteins in conditions of oxidative stress and endoplasmic reticulum stress, respectively. However, individual members of the PDI family may contribute uniquely to the pathogenesis of diabetes and cancer. Studies of exemplary members such as protein disulfide isomerase-associated (PDIA) 1, PDIA6, and PDIA15 were reviewed to highlight their contributions in the pathogenesis of diabetes and cancer and how they can be potential links bridging the two disorders through the cross talk of signaling pathways. Future Directions: Apparently ubiquitous presence of the PDIs creates difficulties and challenges for scientific community to develop targeted therapeutics for the treatment of diabetes and cancer simultaneously. Understanding molecular contribution of individual PDI in the context of specific disease may provide some insights into the development of mechanism-based target-directed therapeutics. Antioxid. Redox Signal. 37, 1191-1205.

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

CONTEXT

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

OBJECTIVE

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

MATERIAL AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Antioxidants affect endoplasmic reticulum stress-related diseases

The endoplasmic reticulum (ER) is a complex multifunctional organelle that maintains cell homeostasis. Intrinsic and extrinsic factors alter ER functions, including the rate of protein folding that triggers the accumulation of misfolded proteins and alters homeostasis, thus generating stress in the ER, which activates the unfolded protein response (UPR) pathway to promote cell survival and restore their homeostasis; however, if the damage is not corrected, it could also trigger cell death. In addition, ER stress and oxidative stress are closely related because excessive production of reactive oxygen species (ROS), a well-known inducer of ER stress, promotes the accumulation of misfolded proteins; at the same time, the ER stress enhances ROS production, generating a pathological cycle. Furthermore, it has been described that the dysregulation of the UPR contributes to the progression of various diseases, so the use of compounds capable of regulating ER stress, such as antioxidants, has been used in several experimental models of diseases to alleviate the damage induced by the maladaptive signaling of the UPR, the mechanism of action of antioxidants generally is dose-dependent, and it is specific in each tissue and pathology, could decrease or enhance specific proteins of the UPR to have beneficial or detrimental effects.

Endoplasmic reticulum stress targeted therapy for breast cancer

Recurrence, metastasis, and drug resistance are still big challenges in breast cancer therapy. Internal and external stresses have been proven to substantially facilitate breast cancer progression through molecular and systemic mechanisms. For example, endoplasmic reticulum stress (ERS) results in activation of the unfolded protein response (UPR), which are considered an important cellular stress response. More and more reports indicate its key role in protein homeostasis and other diverse functions involved in the process of breast cancer progression. Therefore, therapies targeting the activation of ERS and its downstream signaling pathways are potentially helpful and novel tools to counteract and fight breast cancer. However, recent advances in our understanding of ERS are focused on characterizing and modulating ERS between healthy and disease states, and so little attention has been paid to studying the role and clinical application of targeting ERS in a certain cancer. In this review, we summarize the function and main mechanisms of ERS in different molecular types of breast cancer, and focus on the development of agents targeting ERS to provide new treatment strategies for breast cancer.

Optimizing the Live Attenuated Influenza A Vaccine Backbone for High-Risk Patient Groups

Together with inactivated influenza vaccines (IIV), live attenuated influenza vaccines (LAIV) are an important tool to prevent influenza A virus (IAV) illnesses in patients. LAIVs present the advantages to have a needle-free administration and to trigger a mucosal immune response. LAIV is approved for healthy 2- to 49-year old individuals. However, due to its replicative nature and higher rate of adverse events at-risk populations are excluded from the benefits of this vaccine. Using targeted mutagenesis, we modified the nonstructural protein 1 of the currently licensed LAIV in order to impair its ability to bind the host cellular protein CPSF30 and thus its ability to inhibit host mRNA poly-adenylation. We characterized our optimized LAIV (optiLAIV) in three different mouse models mimicking healthy and high-risk patients. Using a neonatal mouse model, we show faster clearance of our optimized vaccine compared to the licensed LAIV. Despite lower replication, optiLAIV equally protected mice against homosubtypic and hetesubtypic influenza strain challenges. We confirmed the safer profile of optiLAIV in Stat1^-/- mice (highly susceptible to viral infections) by showing no signs of morbidity compared to a 50% mortality rate observed following LAIV inoculation. Using a human nasal 3D tissue model, we showed an increased induction of ER stress-related genes following immunization with optiLAIV. Induction of ER stress was previously shown to improve antigen-specific immune responses and is proposed as the mechanism of action of the licensed adjuvant AS03. This study characterizes a safer LAIV candidate in two mouse models mimicking infants and severely immunocompromised patients and proposes a simple attenuation strategy that could broaden LAIV application and reduce influenza burden in high-risk populations. IMPORTANCE Live attenuated influenza vaccine (LAIV) is a needle-free, mucosal vaccine approved for healthy 2- to 49-year old individuals. Its replicative nature and higher rate of adverse events excludes at-risk populations. We propose a strategy to improve LAIV safety and explore the possibility to expand its applications in children under 2-year old and immunocompromised patients. Using a neonatal mouse model, we show faster clearance of our optimized vaccine (optiLAIV) compared to the licensed LAIV. Despite lower replication, optiLAIV equally protected mice against influenza virus challenges. We confirmed the safer profile of optiLAIV in Stat1^-/- mice (highly susceptible to viral infections) by showing no signs of morbidity compared to a 50% mortality rate from LAIV. OptiLAIV could expand the applications of the current LAIV and help mitigate the burden of IAV in susceptible populations.

Molecular mechanisms of programmed cell death in methamphetamine-induced neuronal damage

Methamphetamine, commonly referred to as METH, is a highly addictive psychostimulant and one of the most commonly misused drugs on the planet. Using METH continuously can increase your risk for drug addiction, along with other health complications like attention deficit disorder, memory loss, and cognitive decline. Neurotoxicity caused by METH is thought to play a significant role in the onset of these neurological complications. The molecular mechanisms responsible for METH-caused neuronal damage are discussed in this review. According to our analysis, METH is closely associated with programmed cell death (PCD) in the process that causes neuronal impairment, such as apoptosis, autophagy, necroptosis, pyroptosis, and ferroptosis. In reviewing this article, some insights are gained into how METH addiction is accompanied by cell death and may help to identify potential therapeutic targets for the neurological impairment caused by METH abuse.

ROS and Endoplasmic Reticulum Stress in Pulmonary Disease

Pulmonary diseases are main causes of morbidity and mortality worldwide. Current studies show that though specific pulmonary diseases and correlative lung-metabolic deviance own unique pathophysiology and clinical manifestations, they always tend to exhibit common characteristics including reactive oxygen species (ROS) signaling and disruptions of proteostasis bringing about accumulation of unfolded or misfolded proteins in the endoplasmic reticulum (ER). ER is generated by the unfolded protein response. When the adaptive unfolded protein response (UPR) fails to preserve ER homeostasis, a maladaptive or terminal UPR is engaged, leading to the disruption of ER integrity and to apoptosis, which is called ER stress. The ER stress mainly includes the accumulation of misfolded and unfolded proteins in lumen and the disorder of Ca²⁺ balance. ROS mediates several critical aspects of the ER stress response. We summarize the latest advances in of the UPR and ER stress in the pathogenesis of pulmonary disease and discuss potential therapeutic strategies aimed at restoring ER proteostasis in pulmonary disease.

Neurotoxicity of methamphetamine: Main effects and mechanisms

Methamphetamine (METH) is an illicit psychostimulant that is abused throughout the world. METH addiction is also a major public health concern and the abuse of large doses of the drug is often associated with serious neuropsychiatric consequences that may include agitation, anxiety, hallucinations, paranoia, and psychosis. Some human methamphetamine users can also suffer from attention, memory, and executive deficits. METH-associated neurological and psychiatric complications might be related, in part, to METH-induced neurotoxic effects. Those include altered dopaminergic and serotonergic functions, neuronal apoptosis, astrocytosis, and microgliosis. Here we have endeavored to discuss some of the main effects of the drug and have presented the evidence supporting certain of the molecular and cellular bases of METH neurotoxicity. The accumulated evidence suggests the involvement of transcription factors, activation of dealth pathways that emanate from mitochondria and endoplasmic reticulum (ER), and a role for neuroinflammatory mechanisms. Understanding the molecular processes involved in METH induced neurotoxicity should help in developing better therapeutic approaches that might also serve to attenuate or block the biological consequences of use of large doses of the drug by some humans who meet criteria for METH use disorder.