Dynamic interaction of BiP and ER stress transducers in the unfolded-protein response

Mitochondrial damage and ER stress in CB1 receptor antagonist-induced apoptosis in human neuroblastoma SH-SY5Y cells

Cannabinoid receptor type 1 (CB1R) is the key modulator of neuronal viability. CB1R antagonists provide neuroprotective effects on neurotoxicity caused by e.g. neuronal injury. However, the underlying mechanisms and potential limitations of CB1R antagonism remain unclear. Here we investigated the impact of environmental conditions on CB1R antagonist effects. We have found that cell-permeable CB1R antagonists, rimonabant and AM251, induced cell death in human neuroblastoma SH-SY5Y cells under serum-free conditions. Mitochondrial morphological analysis revealed mitochondrial swelling characterized by their network fragmentation and cristae reduction. Phosphoproteomics analysis showed the ER stress signaling pathway PERK/eIF2α/ATF4/CHOP, leading to caspase-dependent apoptosis. These results suggest that CB1R antagonists promote apoptosis via mitochondrial damage and ER stress under serum-free conditions in SH-SY5Y cells. Our findings indicate that while CB1R antagonists may be neuroprotective in certain conditions, they may also pose a neurotoxic risk in environments characterized by cellular stress or nutrient deprivation.

Heat shock proteins in cerebral ischemia-reperfusion injury: Mechanisms and therapeutic implications

Cerebral ischemia-reperfusion injury (CIRI) remains a significant challenge in ischemic stroke treatment. Heat shock proteins (HSPs), a cadre of molecular chaperones, have emerged as pivotal regulators in this pathological cascade. This review synthesizes the latest research on HSPs in CIRI from 2013 to 2024 focusing on their multifaceted roles and therapeutic potential. We explore the diverse cellular functions of HSPs, including regulation of oxidative stress, apoptosis, necroptosis, ferroptosis, autophagy, neuroinflammation, and blood-brain barrier integrity. Key HSPs, such as HSP90, HSP70, HSP32, HSP60, HSP47, and small HSPs, are investigated for their specific mechanisms of action in CIRI. Potential therapeutic strategies targeting HSPs, including HSP inhibitors, traditional Chinese medicine components, and gene therapy, are discussed. This review provides a comprehensive understanding of HSPs in CIRI and offers insights into the development of innovative neuroprotective treatments.

Increased inflammation as well as decreased endoplasmic reticulum stress and translation differentiate pancreatic islets from donors with pre-symptomatic stage 1 type 1 diabetes and non-diabetic donors

AIMS/HYPOTHESIS

Progression to type 1 diabetes is associated with genetic factors, the presence of autoantibodies and a decline in beta cell insulin secretion in response to glucose. Very little is known regarding the molecular changes that occur in human insulin-secreting beta cells prior to the onset of type 1 diabetes. Herein, we applied an unbiased proteomics approach to identify changes in proteins and potential mechanisms of islet dysfunction in islet-autoantibody-positive organ donors with pre-symptomatic stage 1 type 1 diabetes (HbA1c ≤42 mmol/mol [6.0%]). We aimed to identify pathways in islets that are indicative of beta cell dysfunction.

METHODS

Multiple islet sections were collected through laser microdissection of frozen pancreatic tissues from organ donors positive for single or multiple islet autoantibodies (AAb+, n=5), and age (±2 years)- and sex-matched non-diabetic (ND) control donors ( n=5) obtained from the Network for Pancreatic Organ donors with Diabetes (nPOD). Islet sections were subjected to MS-based proteomics and analysed with label-free quantification followed by pathway and functional annotations.

RESULTS

Analyses resulted in ~4500 proteins identified with low false discovery rate (<1%), with 2165 proteins reliably quantified in every islet sample. We observed large inter-donor variations that presented a challenge for statistical analysis of proteome changes between donor groups. We therefore focused on only the donors with stage 1 type 1 diabetes who were positive for multiple autoantibodies (mAAb+, n=3) and genetic risk compared with their matched ND controls (n=3) for the final statistical analysis. Approximately 10% of the proteins (n=202) were significantly different (unadjusted p<0.025, q<0.15) for mAAb+ vs ND donor islets. The significant alterations clustered around major functions for upregulation in the immune response and glycolysis, and downregulation in endoplasmic reticulum (ER) stress response as well as protein translation and synthesis. The observed proteome changes were further supported by several independent published datasets, including a proteomics dataset from in vitro proinflammatory cytokine-treated human islets and single-cell RNA-seq datasets from AAb+ individuals.

CONCLUSIONS/INTERPRETATION

In situ human islet proteome alterations in stage 1 type 1 diabetes centred around several major functional categories, including an expected increase in immune response genes (elevated antigen presentation/HLA), with decreases in protein synthesis and ER stress response, as well as compensatory metabolic response. The dataset serves as a proteomics resource for future studies on beta cell changes during type 1 diabetes progression and pathogenesis.

DATA AVAILABILITY

The LC-MS raw datasets that support the findings of this study have been deposited in the online repository: MassIVE ( https://massive.ucsd.edu/ProteoSAFe/static/massive.jsp ) with accession no. MSV000090212.

Regulating islet stress responses through CD47 activation

AIMS/HYPOTHESIS

Diabetes is a global health burden characterised by incremental beta cell loss. Islet transplantation is a recognised treatment for individuals with type 1 diabetes and hypoglycaemia unawareness but broader application is constrained by limited islet survival and function post-transplantation. The underlying molecular mechanisms that induce beta cell dysfunction and demise remain unclear, and therapeutic agents that protect against cellular loss and maintain insulin secretion are in demand as potential treatment options. CD47 is a cell surface protein implicated in cellular stress responses but its role in beta cell function remains relatively unexplored. We hypothesised that modulating CD47 expression would demonstrate a cytoprotective effect in beta cells.

METHODS

We used primary murine islets with/without genetic deletion of CD47, as well as human islets and MIN6 cells subjected to pharmacological disruption of CD47 signalling (siRNA or blocking antibody). Metabolic stress was induced in cells by exposure to hypoxia, hyperglycaemia or thapsigargin, and markers of the unfolded protein response, cell survival and insulin secretory function were assessed. Human pancreases from individuals with and without diabetes were examined for evidence of CD47 signalling.

RESULTS

Expression of CD47 and its high affinity ligand thrombospondin-1 (TSP1) was robustly upregulated by exogenous stressors. Limiting CD47 signalling improved markers of senescence, apoptosis, endoplasmic reticulum stress, unfolded protein response, self-renewal and autophagy, and maintained insulin secretory responses. We also found concurrent upregulated expression of CD47 and senescence markers in the endocrine pancreas of aged donors and those with type 2 diabetes. Both CD47 and TSP1 expression were increased in pancreases of humans with type 1 diabetes, as were plasma levels of TSP1.

CONCLUSIONS/INTERPRETATION

Our study provides key insights into the essential role of CD47 as a novel regulator of islet dysfunction, regulating cytoprotective responses to stress. CD47 may contribute to beta cell damage during the development of diabetes and failure of islet transplant function. Therefore, limiting CD47 activation may be a potential therapeutic tool in conditions where islet function is inadequate.

PARP-16 regulates the PERK and IRE-1α Mediated Unfolded Protein Response in Japanese Encephalitis Virus-Infected Neural Stem/Progenitor Cells

The viral infection and subsequent accumulation of viral proteins in the infected cells leads to endoplasmic reticulum (ER) stress. Japanese encephalitis virus (JEV) infection in the Central Nervous System (CNS) has been shown to induce unfolded protein response (UPR). The ER stress is resolved by the UPR which comprises certain signals that are transduced from the ER either to both the cytoplasm or nucleus, resulting in the adaptation for survival or may even lead to apoptosis. Here, we demonstrate that Poly ADP-ribose polymerase-16 (PARP-16) expression is regulating the ER stress response following JEV infection of Neural Stem/Progenitor cells (NSPCs) in the BALB/c mouse model. Activation of the key sensors of UPR, namely, protein kinase R (PKR)-like ER kinase (PERK) and Inositol-requiring enzyme-1α (IRE-1α) by PARP-16 upon JEV infection, led to the activation of their downstream signalling cascade. The siRNA-mediated in vitro downregulation of PARP-16 in NSPCs alleviated the overall UPR, as the abundance of UPR markers and their downstream modulators of signalling cascade was found to be downregulated. These results highlight an important role of PARP-16 during JEV infection of NSPCs.

A BiP-centric View of Endoplasmic Reticulum Functions and of My Career

After completing my post-doctoral training at the University of Alabama, Birmingham and a brief period on the faculty there, I joined the Department of Tumor Cell Biology at St. Jude Children's Research Hospital in 1987 as an Assistant Member and started my independent research program. For the following 37 years, I led a relatively small basic research group comprised at various times of post-doctoral fellows, graduate students, undergraduate students, and research technicians; many of whom I am still in contact. Last year I closed the lab and transitioned to an emeritus position at St. Jude. I continue to maintain several research collaborations covering areas of research that have long been dear to my heart. My post-doctoral studies on BiP revealed that it controlled immunoglobulin assembly and transport, and as such, played a critical role in the fidelity of the immune response. My lab continued to define BiP's functions in protein folding and subunit assembly, as well as, in degradation of proteins that failed to mature properly using biochemical, cell-based, and biophysical analyses. Several ER localized co-factors that regulate the activity of BiP and allow it to contribute to its multiple ER functions were identified by our group. These include DnaJ family members and nucleotide change factors. Through a variety of collaborative studies, we pursued BiP's functions in maintaining the permeability barrier of the translocon, contributing to ER calcium stores, and regulating the up-stream transducers of the UPR, a stress response that is activated by the accumulation of unfolded proteins in the ER.

Irisin: muscle's novel player in endoplasmic reticulum stress and disease

Irisin, an exercise-induced myokine, exhibits elevated levels during physical activity, yet its role in modulating the unfolded protein response (UPR) remains poorly understood. This comprehensive review pioneers an in-depth examination of irisin-mediated endoplasmic reticulum (ER) stress mitigation across various diseases. We provide a nuanced characterization of irisin's molecular profile, biological activity, and significance as a skeletal muscle-derived cytokine analogue. Our discussion elucidates the complex interplay between exercise, irisin signalling, and metabolic outcomes, highlighting key molecular interactions driving salutary effects. Moreover, we delineate the UPR's role as a critical ER stress countermeasure and underscore irisin's pivotal function in alleviating this stress, revealing potential therapeutic avenues for disease management. Exercise-induced release of irisin ameliorates ER stress through AMPK phosphorylation during various diseases (Icon image source: www.flaticon.com ).

Independent and Combined Effects of Particulate Matter and Sleep Deprivation on Human Skin Barrier

BACKGROUND

The exposome encompasses all factors people encounter through life, with the skin constantly exposed. While particulate matter (PM) and sleep deprivation are known to contribute to barrier dysfunction, their combined effects remain unclear.

OBJECTIVE

To evaluate the independent and combined effects of PM exposure and short-term sleep deprivation on skin barrier function.

METHODS

Forty healthy Korean women (aged 24-58 years) were enrolled in this study. Forearms were divided into 4 sites: control, PM exposure, sleep deprivation, and PM plus sleep deprivation. Parameters such as trans-epidermal water loss (TEWL), hydration, elasticity, roughness, and redness were measured at baseline and post-exposure. RNA sequencing and reverse transcription-polymerase chain reaction were conducted on tape-stripped skin samples.

RESULTS

PM exposure significantly increased TEWL (+25.59%, p<0.01), roughness (+21.9%, p<0.01), and redness (+13.7%, p<0.0001) while reducing elasticity (-3.98%, p<0.01). Sleep deprivation modestly reduced elasticity (-1.39%, p<0.05) without affecting other parameters. Combined PM and sleep deprivation did not further exacerbate barrier dysfunction compared to PM alone. RNA sequencing revealed reduced FLG and LORICRIN expression and upregulated endoplasmic reticulum (ER) stress markers (HSP90B1, CANX) in both PM and sleep deprivation conditions.

CONCLUSION

PM exposure impaired skin barrier function, while short-term sleep deprivation alone did not significantly affect the barrier, either independently or in combination with PM. However, it was observed that the sleep deprivation-only, while not directly causing barrier damage, induced changes in ER stress-related gene expression in tape-stripped skin samples, like the PM exposure-only. This suggests that such signaling pathways could potentially exacerbate skin barrier deterioration.

Impact of proteostasis workload on sensitivity to proteasome inhibitors in multiple myeloma

Genomic alterations and enormous monoclonal immunoglobulin production cause multiple myeloma to heavily depend on proteostasis mechanisms, including protein folding and degradation. These findings support the use of proteasome inhibitors for treating multiple myeloma and mantle cell lymphoma. Myeloma treatment has evolved, especially with the availability of new drugs, such as proteasome inhibitors, into therapeutic strategies for both frontline and relapsed/refractory disease settings. However, proteasome inhibitors are generally not effective enough to cure most patients. Natural resistance and eventual acquired resistance led to relapsed/refractory disease and poor prognosis. Advances in the understanding of cellular proteostasis and the development of innovative drugs that also target other proteostasis network components offer opportunities to exploit the intrinsic vulnerability of myeloma cells. This review outlines recent findings on the molecular mechanisms regulating cellular proteostasis pathways, as well as resistance, sensitivity, and escape strategies developed against proteasome inhibitors and provides a rationale and examples for novel combinations of proteasome inhibitors with FDA-approved drugs and investigational drugs targeting the NRF1 (NFE2L1)-mediated proteasome bounce-back response, redox homeostasis, heat shock response, unfolding protein response, autophagy, and VCP/p97 to increase proteotoxic stress, which can improve the efficacy of antimyeloma therapy based on proteasome inhibitors.

Investigation of the protective effect of beta caryophyllene against indomethacin-induced gastric ulcer in rats: in vivo and in vitro study

In this study, the protective and healing effects of beta-caryophyllene (BCP) on gastric mucosa in indomethacin (INDO)-induced gastric ulcer model were investigated. In the study, 116 male Sprague-Dawley rats were used. In in vivo experiments, rat was administered doses of 50-100-200 mg/kg BCP and 5 mg/kg omeprazole for 14 days, and indomethacin (100 mg/kg) was given on the last day. In in vitro experiments, the effects of BCP (250-500-1000 µg/ml) on gastric motility and acid secretion were examined by isolated organ bath method. It was found that INDO treatment increased MDA level in gastric tissue, but decreased GPx and SOD activities. Nrf2 and HO-1 levels were decreased in INDO-treated groups. INDO increased TNF-α, IL-1β, and NF-κB levels and iNOS activity, but decreased COX-1 activity and PGE2 levels. INDO induced ER stress and increased GRP78, ATF4, ATF6, p-IRE1, sXBP1, eIF2-α, and CHOP expression levels in gastric tissue. Bax, caspase-3, and caspase-12 levels increased in INDO group, while Bcl-2 level decreased. BCP showed protective activity in gastric tissue and brought these parameters closer to normal levels. In vitro studies revealed that BCP decreased ACh and KCl-induced gastric contractions. Again, BCP decreased gastric acid secretion via M3 receptor pathway but not via H2 and CCK2 receptor pathways. This study revealed that BCP showed healing effects by protecting gastric mucosa from oxidative stress, inflammation, ER stress, and apoptosis in INDO-induced gastric ulcer model. In addition, it was revealed that BCP affects gastric motility by regulating gastric acid secretion via M3 receptor pathway.

Thioredoxin: a key factor in cold tumor formation and a promising biomarker for immunotherapy resistance in NSCLC

Immune checkpoint blockade (ICB) therapy has shown promising clinical efficacy in cancer treatment, but only a subset of patients experience significant therapeutic responses. Tumor cells respond to internal and external stresses, such as hypoxia and nutrient deprivation, by activating the unfolded protein response (UPR) in the tumor microenvironment. This response helps maintain homeostasis, promoting malignant progression, chemotherapy resistance, and immune escape. In this study, single-cell RNA sequencing (scRNA-seq) data from non-small cell lung cancer (NSCLC) patients treated with ICB revealed upregulation of thioredoxin (TXN) expression in the epithelial tissues of LUAD (lung adenocarcinoma) and LUSC (lung squamous cell carcinoma) patients with minimal pathological remission. High TXN expression was also associated with "cold tumors," characterized by a lack of T cells and low levels of chemokine receptors and immunomodulators. Experimental results showed that TXN was highly expressed in NSCLC tissues, and its knockdown significantly inhibited the proliferation and migration of A549 and SK-MES-1 cells. Furthermore, TXN knockdown enhanced T-cell-mediated cytotoxicity against these tumor cells, suggesting that TXN contributes to immune escape in NSCLC by promoting tumor cell proliferation and migration while inhibiting immune killing. Notably, TXN knockdown also upregulated CD40 expression, indicating that TXN may regulate immune escape in lung cancer through CD40 modulation.

Investigation and validation of genes associated with endoplasmic reticulum stress in diabetic retinopathy using various machine learning algorithms

BACKGROUND

Diabetic retinopathy (DR) is a common complication of diabetes, with Endoplasmic reticulum stress (ERS) playing a key role in cellular adaptation, injury, or apoptosis, impacting disease pathology. This study aimed to identify early diagnostic markers for personalized DR treatment.

METHODS

DR and healthy control (HC) samples were collected from the Gene Expression Omnibus (GEO) database. Differentially expressed ERS-related genes (DE-ERSRGs) were identified, and machine learning algorithms were used to pinpoint DR-specific feature DE-ERSRGs (FDE-ERSRGs). Diagnostic accuracy was assessed using ROC curve analysis. Further analyses included differential expression, co-expression, GO functional, KEGG pathway enrichment, and immune cell infiltration profiling in DR.

RESULTS

A total of 55 DE-ERSRGs were initially identified, and after further analysis, two key FDE-ERSRGs, SELENOS and heat shock protein family A member 5 (HSPA5), were highlighted due to their robust differential expression patterns between DR and healthy controls. Both genes exhibited high diagnostic potential, with AUC values of 0.792 and 0.799, respectively, indicating their promise as biomarkers for DR. Additionally, we examined the differential and co-expression patterns of DE-ERSRGs between high- and low-expression groups. We investigated the molecular functions and biological pathways associated with DR, analyzed immune cell infiltration differences between DR and HC groups, and assessed their correlation with FDE-ERSRGs.

CONCLUSIONS

Our findings provide new insights into the molecular mechanisms and metabolic pathways involved in DR, potentially paving the way for the identification of novel diagnostic and immunotherapeutic biomarkers.

Impact of ER stress and the unfolded protein response on Fabry disease

Fabry disease (FD) is a lysosomal storage disorder caused by pathogenic missense and nonsense variants in the α-galactosidase A (GLA) gene, leading to absent or reduced enzyme activity. The resulting lysosomal accumulation of the substrate globotriaosylceramide leads to progressive renal failure, cardiomyopathy with (malignant) cardiac arrhythmias and progressive heart failure as well as recurrent strokes, which significantly limits the life expectancy of patients affected with FD. There is increasing evidence that pathogenic GLA missense variants as well as formally benign GLA variants can cause retention in the endoplasmic reticulum (ER), resulting in ER stress, which in turn triggers an unfolded protein response (UPR) leading to cellular dysregulation including inflammation, irreversible cell damage, and apoptosis. This review aims to provide an update on the pathogenetic significance of ER stress and UPR in FD, current treatment options, including pharmaceutical and chemical chaperones, and an outlook on current research and future treatment options in FD.

GRP78 Nanobody-Directed Immunotoxin Activates Innate Immunity Through STING Pathway to Synergize Tumor Immunotherapy

The lack of targetable antigens poses a significant challenge in developing effective cancer-targeted therapies. Cell surface translocation of endoplasmic reticulum (ER) chaperones, such as glucose-regulated protein 78 (GRP78), during malignancy, drug resistance, and ER stress induced by therapies, offers a promising pan-cancer target. To target GRP78, nanobody C5, identified from a phage library and exhibiting high affinity for human and mouse GRP78, is utilized to develop the Pseudomonas exotoxin (PE) immunotoxin C5-PE38. C5-PE38 induced ER stress, apoptosis and immunogenic cell death in targeted cells and showed antitumor efficacy against colorectal cancer and melanoma models without obvious toxicity. Mechanistically, transcriptome profiling showed that C5-PE38 reshaped the tumor immune microenvironment with enhanced innate and adaptive immune response and response to interferon beta. Moreover, C5-PE38-induced cell death could trans-activate STING pathway in dendritic cells and macrophages, promoting CD8+ T cell infiltration. It also sensitizes both primary and metastatic melanomas to anti-PD1 therapy, partly through STING activation. Overall, this study unveils a feasible GRP78 nanobody-directed therapy strategy for single or combinatorial cancer intervention. This work finds that C5-PE38-induced cell death stimulates STING-dependent cytosolic DNA release to promote antitumor immunity, a mechanism not previously reported for PE38, providing valuable insights for its clinical use.

Pre-clinical model of dysregulated FicD AMPylation causes diabetes by disrupting pancreatic endocrine homeostasis

The bi-functional enzyme FicD catalyzes AMPylation and deAMPylation of the endoplasmic reticulum chaperone BiP to modulate ER homeostasis and the unfolded protein response (UPR). Human hFicD with an arginine-to-serine mutation disrupts FicD deAMPylation activity resulting in severe neonatal diabetes. We generated the mFicDR371S mutation in mice to create a pre-clinical murine model for neonatal diabetes. We observed elevated BiP AMPylation levels across multiple tissues and signature markers for diabetes including glucose intolerance and reduced serum insulin levels. While the pancreas of mFicDR371S mice appeared normal at birth, adult mFicDR371S mice displayed disturbed pancreatic islet organization that progressed with age. mFicDR371S mice provide a preclinical mouse model for the study of UPR associated diabetes and demonstrate the essentiality of FicD for tissue resilience.

YC-4-3, a Novel Glycogen Synthase Kinase 3β Inhibitor, Alleviates the Endoplasmic Reticulum Stress of Macrophages in Primary Immune Thrombocytopenia

Primary immune thrombocytopenia (ITP) is a heterogeneous autoimmune disease, characterized by decreased platelet count and increased risk of hemorrhage, in which macrophages play an important role in the pathogenesis. This study aims to explore the effects of YC-4-3, the patented chemical synthesis of benzothiazepinone compounds (BTZs), a novel GSK-3β inhibitor (GSK-3βi), on macrophages in ITP. The expressions of GSK-3β in monocytes are tested. The effects of GSK-3βi (YC-4-3) on macrophages of ITP patients are examined and validated in passive and active murine models. Signal pathway enrichment analysis is performed. The interaction proteins of endoplasmic reticulum (ER) stress and GSK-3β are explored. The GSK-3β+ cells in monocytes are increased in newly diagnosed ITP patients and decreased in treatment-response patients. YC-4-3 can restrain the proinflammatory differentiation, phagocytosis, and cytokine generation of macrophages and alleviate thrombocytopenia in ITP. YC-4-3 suppresses the PI3K/mTOR/Akt, NFκB/IκBα, and MAPK pathways, as well as the ER stress signal pathway. YC-4-3 directly interacts with the protein chaperone Bip. YC-4-3, a patented GSK-3βi, can modulate the inflammatory status of macrophages and improve the thrombocytopenia in ITP by directly interacting with ER stress response. YC-4-3 may be a novel potential therapeutic agent for ITP.

SRP19 and the protein secretion machinery is a targetable vulnerability in cancers with APC loss

Loss of the tumor suppressor gene (TSG) Adenomatous Polyposis Coli (APC) is a hallmark event in colorectal cancers. Since it is not possible to directly target a TSG, no treatment options are available for these patients. Here, we identify SRP19 and the protein secretion machinery as a unique vulnerability in cancers with heterozygous APC loss. SRP19 is located 15 kb from APC and is almost always codeleted in these tumors. Heterozygous APC/SRP19 loss leads to lower levels of SRP19 mRNA and protein. Consequently, cells with APC/SRP19 loss are vulnerable to partial suppression of SRP19. Moreover, we show that SRP19 is rate limiting for the formation of the Signal Recognition Particle, a complex that mediates ER-protein translocation, and thus, heterozygous SRP19 loss leads to less protein secretion and higher levels of ER-stress. As a result, low-dose arsenic trioxide induces ER-stress and inhibits proliferation in cultured cell lines and animal models. Our work identifies a strategy to treat cancers with APC deletion and provides a framework for identifying and translating vulnerabilities associated with loss of a TSG.

Improving data interpretability with new differential sample variance gene set tests

BACKGROUND

Gene set analysis methods have played a major role in generating biological interpretations of omics data such as gene expression datasets. However, most methods focus on detecting homogenous pattern changes in mean expression while methods detecting pattern changes in variance remain poorly explored. While a few studies attempted to use gene-level variance analysis, such approach remains under-utilized. When comparing two phenotypes, gene sets with distinct changes in subgroups under one phenotype are overlooked by available methods although they reflect meaningful biological differences between two phenotypes. Multivariate sample-level variance analysis methods are needed to detect such pattern changes.

RESULTS

We used ranking schemes based on minimum spanning tree to generalize the Cramer-Von Mises and Anderson-Darling univariate statistics into multivariate gene set analysis methods to detect differential sample variance or mean. We characterized the detection power and Type I error rate of these methods in addition to two methods developed earlier using simulation results with different parameters. We applied the developed methods to microarray gene expression dataset of prednisolone-resistant and prednisolone-sensitive children diagnosed with B-lineage acute lymphoblastic leukemia and bulk RNA-sequencing gene expression dataset of benign hyperplastic polyps and potentially malignant sessile serrated adenoma/polyps. One or both of the two compared phenotypes in each of these datasets have distinct molecular subtypes that contribute to within phenotype variability and to heterogeneous differences between two compared phenotypes. Our results show that methods designed to detect differential sample variance provide meaningful biological interpretations by detecting specific hallmark gene sets associated with the two compared phenotypes as documented in available literature.

CONCLUSIONS

The results of this study demonstrate the usefulness of methods designed to detect differential sample variance in providing biological interpretations when biologically relevant but heterogeneous changes between two phenotypes are prevalent in specific signaling pathways. Software implementation of the methods is available with detailed documentation from Bioconductor package GSAR. The available methods are applicable to gene expression datasets in a normalized matrix form and could be used with other omics datasets in a normalized matrix form with available collection of feature sets.

Cannabidiol Enhances the Anticancer Activity of Etoposide on Prostate Cancer Cells

Introduction: Cannabis sativa extract has been used as an herbal medicine since ancient times. It is one of the most researched extracts, especially among supportive treatments against cancer. Prostate cancer is one of the most frequently diagnosed cancer types in men worldwide and an estimated 288,300 new cases were diagnosed in 2023. Today, many advanced therapeutic approaches are used for prostate cancer, such as immunotherapy and chemotherapy, but acquired drug resistance, long-term drug usage and differentiation of cancer cells mostly restricted the efficiency of therapies. Therefore, it is thought that the use of natural products to overcome these limitations and improve the effectiveness of existing therapies may offer promising approaches. The present study focused on the investigation of the possible enhancer role of cannabidiol (CBD), which is a potent ingredient compound of Cannabis, on the chemotherapeutic agent etoposide in prostate cancer cells. Methods: Herein, we tested the potentiator role of CBD on etoposide in prostate cancer cells by testing the cytotoxic effect, morphological alterations, apoptotic effects, autophagy, unfolded protein response (UPR) signaling, endoplasmic reticulum-associated degradation mechanism (ERAD), angiogenic and androgenic factors, and epithelial-mesenchymal transition (EMT). In addition, we examined the combined treatment of CBD and etoposide on colonial growth, migrative, invasive capability, 3D tumor formation, and cellular senescence. Results: Our findings demonstrated that cotreatment of etoposide with CBD importantly suppressed autophagic flux and induced ERAD and UPR signaling in LNCaP cells. Also, CBD strongly enhanced the etoposide-mediated suppression of androgenic signaling, angiogenic factor VEGF-A, protooncogene c-Myc, EMT, and also induced apoptosis through activation caspase-3 and PARP-1. Moreover, coadministration markedly decreased tumorigenic properties, such as proliferative capacity, colonial growth, migration, and 3D tumor formation and also induced senescence. Altogether, our data revealed that CBD has a potent enhancer effect on etoposide-associated anticancer activities. Conclusion: The present study suggests that the use of CBD as a supportive therapy in existing chemotherapeutic approaches may be a promising option, but this effectiveness needs to be investigated on a large scale.

A novel TLR4 accessory molecule drives hepatic oncogenesis through tumor-associated macrophages

Tumor-associated macrophages (TAMs) play a crucial role in the tumor microenvironment, yet the roles and mechanisms of TAMs in inflammation-associated oncogenesis remain enigmatic. We report that protein canopy homolog 2 (CNPY2) functions as a novel TLR4 regulator, promoting cytokine production in macrophages. CNPY2 binds directly to TLR4. Cnpy2 deficiency reduces cell surface expression of TLR4, nuclear translocation of NFκB and cytokine production in macrophages. Macrophage-specific CNPY2 deficiency significantly decreases cytokine production in macrophages and reduces hepatocarcinogenesis in a diethylnitrosamine (DEN)-induced liver cancer model. RNA-sequencing analysis revealed Cnpy2 knockout decreased the mRNA level and cell surface expression of two VEGF receptors, Flt1 and Kdr, compared to those in WT counterparts, resulting in inhibition of macrophage tumor infiltration. Cnpy2 knockout inhibits NFκB2/p52-mediated transcription of Flt1 and Kdr in macrophages. These findings demonstrate that CNPY2 regulates macrophages in both inflammation and hepatocarcinogenesis and may serve as a therapeutic target for cancer.

A nonenzymatic dependency on inositol-requiring enzyme 1 controls cancer cell cycle progression and tumor growth

Endoplasmic-reticulum resident inositol-requiring enzyme 1α (IRE1) supports protein homeostasis via its cytoplasmic kinase-RNase module. Known cancer dependency on IRE1 entails its enzymatic activation of the transcription factor XBP1s and of regulated RNA decay. We discovered surprisingly that some cancer cell lines require IRE1 but not its enzymatic activity. IRE1 knockdown but not enzymatic IRE1 inhibition or XBP1 disruption attenuated cell cycle progression and tumor growth. IRE1 silencing led to activation of TP53 and CDKN1A/p21 in conjunction with increased DNA damage and chromosome instability, while decreasing heterochromatin as well as DNA and histone H3K9me3 methylation. Immunoelectron microscopy detected some endogenous IRE1 protein at the nuclear envelope. Thus, cancer cells co-opt IRE1 either enzymatically or nonenzymatically, which has significant implications for IRE1's biological role and therapeutic targeting.

Differential Induction of Endoplasmic Reticulum Stress Signaling by Antibody Isotypes: Implications for Plasma Cell Differentiation

IgE induces stronger ER stress than IgG1 due to its constant region, particularly the Cε3 domain, which binds BiP more efficiently. Genetic and structural analyses confirmed IgE's higher BiP-binding capacity. ER stress, driven by IRE1-XBP1 signaling, regulates plasma cell differentiation, suggesting IgE-specific mechanisms in immune responses.

Neuroprotective Effects of Lilium Lancifolium Thunberg Extract Against Corticosterone-Induced Dysfunctions in PC12 Cells

Chronic stress in the central nervous system can lead to neurological dysfunction characterized by spontaneous neuronal cell death. This study investigated the neuroprotective potential of an aqueous extract of Lilium lancifolium Thunberg (ELL) against corticosterone (CORT)-induced pathophysiology in PC12 cells. To assess the neuroprotective effects of ELL, PC12 cells were pretreated with 50 µg/mL of ELL before being exposed to CORT. ELL significantly prevented CORT-induced neuronal cell death by attenuating pro-apoptotic protein expression, lactate dehydrogenase release, and reactive oxygen species generation, while maintaining intact adenosine triphosphate levels. Furthermore, ELL significantly mitigated CORT-induced endoplasmic reticulum (ER) stress responses by attenuating the elevation of unfolded protein responses, intracellular calcium levels, opening of mitochondrial permeability transition pores, and loss of mitochondrial membrane potential. In conclusion, ELL exerts neuroprotective effects by inhibiting apoptosis through the mitigation of CORT-induced ER stress and mitochondrial dysfunction, suggesting that ELL may prevent neuronal damage associated with chronic stress-induced neurotoxicity.

Endocytic Uptake of Self-Assembled Iridium(III) Nanoaggregates for Holistic Treatment of Metastatic 3D Triple-Negative Breast Tumor Spheroids

Triple-negative breast cancer (TNBC) presents a formidable challenge due to its aggressive behavior and limited array of treatment options available. This study focuses on employing nanoaggregate material of organometallic Ir(III) complexes for treating TNBC cell line MDA-MB-231. In this approach, Ir(III) complexes with enhanced cellular permeability are strategically designed and achieved through the incorporation of COOMe groups into their structure. The lead compound, IrL1, exhibits promiscuous nanoscale aggregation in RPMI cell culture media, characterized by a stable hydrodynamic effective diameter ranging from 190 to 202 nm over 48 h. With excellent photo-responsive contrast-enhanced cell imaging properties IrL1 exhibits an outstanding IC50, 48h value of 36.05± 0.03 nm when irradiated with 390 nm light in MDA-MB-231 (IC50, 48 h of Cisplatin is 5.29 µµ). In cell, investigation confirms that IrL1 nanoaggregates internalization via energy-dependent endocytosis undergo ferroptosis and ROS mediated cell death in MDA-MB-231 cells. Further, these in vivo studies using NOD-SCID mice confirmed that IrL1 exhibits a tendency to ablate tumors inoculated in mice models at therapeutically relevant doses. Thus, this comprehensive approach holds promise for expanding the repertoire of organometallic Ir(III) nanoaggregates with adaptable characteristics, thereby advancing their clinical utility of nanomedicine in the holistic treatment of metastatic 3D triple-negative breast tumor spheroids.

Skeletal muscle atrophy induced by aging and disuse atrophy are strongly associated with the upregulation of the endoplasmic stress protein CHOP in rats

BACKGROUND

While canonical anabolic and proteolytic pathways have been well examined in the context of skeletal muscle proteostasis, the roles of endoplasmic reticulum stress (ERS) and the induced unfolded protein response (UPR) are underappreciated. Thus, we aimed to determine whether aging and/or disuse atrophy in rats altered skeletal muscle ERS/UPR markers.

METHODS AND RESULTS

Soleus (SOL) and plantaris (PLT) muscles of 3-month-old (mo), 6 mo, 12 mo, 18 mo, and 24 mo rats (9-10 per group, 48 in total) were analyzed for UPR proteins with further analysis performed on the protein CHOP. The gastrocnemius muscles of 4 mo rats that had undergone hindlimb immobilization (HLI, n = 12) or sham casting (CTL, n = 12) were analyzed for similar targets as well as more extensive CHOP-related targets. CHOP protein was greater in the PLT and SOL of 18 and 24 mo rats versus other age groups (P < 0.05). Moreover, negative correlations existed between CHOP expression and normalized PLT (R=-0.702, P < 0.001) and SOL (R=-0.658, P < 0.001) muscle weights in all rats analyzed at different ages. CHOP protein expression was also greater in the gastrocnemius of HLI versus CTL rats (P < 0.001), and a negative correlation existed between CHOP protein expression and normalized muscle weights in these rats (R=-0.814, P < 0.001). Nuclear CHOP protein levels (P < 0.010) and genes transcriptionally regulated by CHOP were also greater in HLI versus CTL rats (P < 0.001) implicating transcriptional activity of CHOP is elevated during disuse atrophy.

CONCLUSIONS

CHOP is operative during aging- and disuse-induced skeletal muscle atrophy in rodents, and more research is needed to determine if CHOP is a key mechanistic driver of these processes.

Mitochondria associated membranes in dilated cardiomyopathy: connecting pathogenesis and cellular dysfunction

Dilated cardiomyopathy (DCM) is a leading cause of heart failure, yet therapeutic options remain limited. While traditional research has focused on mechanisms such as energy deficits and calcium dysregulation, increasing evidence suggests that mitochondria-associated membranes (MAMs) could provide new insights into understanding and treating DCM. In this narrative review, we summarize the key role of MAMs, crucial endoplasmic reticulum (ER)-mitochondria interfaces, in regulating cellular processes such as calcium homeostasis, lipid metabolism, and mitochondrial dynamics. Disruption of MAMs function may initiate pathological cascades, including ER stress, inflammation, and cell death. These disruptions in MAM function lead to further destabilization of cellular homeostasis. Identifying MAMs as key modulators of cardiac health may provide novel insights for early diagnosis and targeted therapies in DCM.

Hepatoprotective Effects of Royal Jelly Against Vincristine-Induced Hepatotoxicity in Rats: A Biochemical and Molecular Study

Vincristine (VCR) is a chemotherapeutic agent classified as a vinca alkaloid. Royal jelly (RJ) is a significant bee product produced by worker bees, characterized by its high protein content. This study aims to investigate the protective effects of RJ against VCR-induced liver damage. VCR was intraperitoneally administered at a dose of 0.1 mg/kg body weight (b.w.) and RJ was orally administered at doses of 150 and 300 mg/kg b.w. Both treatments were applied to the rats on days 1-6 and 9-14. The composition of RJ was analyzed using LC-MS/MS, revealing the presence of 15 different phytochemical compounds with strong antioxidant properties. Serum samples obtained from the rats were analyzed for ALT, ALP, and AST levels. While these enzyme levels were significantly elevated in the VCR group, a notable reduction was observed following RJ administration. Additionally, SOD, CAT, GPx, and GSH antioxidant parameters, along with MDA levels, were evaluated in liver tissue samples. The results indicated a decrease in SOD, CAT, GPx, and GSH activities/levels and an increase in MDA levels in the VCR group. Furthermore, ELISA was used to assess JAK2, STAT3, and mTOR/PI3K/AKT signaling pathways. VCR administration led to a decrease in mTOR/PI3K/AKT levels and an increase in JAK2 and STAT3 levels. In addition, the mRNA transcription levels of inflammation (NF-κB, TNF-α, and IL-1β), endoplasmic reticulum (ER) stress (IRE-1, GRP78, PERK, and ATF-6), and autophagy markers (LC3A and LC3B) were examined. A significant increase in inflammation, ER stress, and autophagy-related markers was observed in the VCR-treated group. Lastly, the protein expression levels of Bax, Bcl-2, Caspase-3, and NF-κB were evaluated. VCR treatment increased Bax, Caspase 3, and NF-κB levels, whereas Bcl-2 levels were decreased. However, following RJ administration, all these parameters were reversed, demonstrating significant improvements. In conclusion, these findings suggest that RJ may exert a protective effect against VCR-induced liver damage.

Role of endoplasmic reticulum stress in cell apoptosis induced by duck hepatitis A virus type 1 infection

The endoplasmic reticulum (ER), an elaborate cellular organelle that interweaves the cytosol, nucleus, mitochondria and plasma membrane, is essential for cell function and survival. Disruption of ER function can trigger unfolded protein response (UPR), which is activated by ER stress (ERS). In this study, we investigated the role of ERS in cell apoptosis induced by duck hepatitis A virus type 1 (DHAV-1) infection. Our findings revealed that DHAV-1 infection led to the activation of ERS. Specially, the expression of glucose-regulated protein 78 (GRP78) was upregulated, activating two pathways of UPR: the protein kinase R-like ER kinase (PERK) pathway and the inositol-requiring enzyme 1(IRE1) pathway. Consequently, phosphorylation of eukaryotic initiation factor 2 alpha (p-eIF2α) was increased, and transcription factor 4 (ATF4) was up-regulated, resulting in the induction of the apoptotic C/EBP homologous protein (CHOP). DHAV-1-infected cells exhibited various apoptotic phenotypes, including growth arrest, induction of the DNA damage-inducible protein 34 (GADD34), activation of caspase-3, and suppression of antiapoptotic protein B cell lymphoma-2 (Bcl-2). Importantly, inhibition of PERK or protein kinase R (PKR) activity suppressed CHOP activation and DHAV-1 replication, indicating that the PERK/PKR-eIF2α pathway played a crucial role in ERS-induced apoptosis. Collectively, our study provides novel insights into the mechanism of DHAV-1-induced apoptosis and reveals a potential defense mechanism against DHAV-1 replication.

Inhibition of the TRPM2 cation channel attenuates morphine tolerance by modulating endoplasmic reticulum stress and apoptosis in rats

Opioid drugs such as morphine are frequently preferred drugs for severe pain in cancer and chronic diseases, but long-term use causes opioid tolerance. The mechanism of tolerance to opioids is quite complex and not fully understood. Our aim in this study was to investigate the effects of TRPM2 cation channel antagonists N-(p-amylcinnamoyl) anthranilic acid (ACA) and 2-aminoethoxydiphenyl borate (2-APB) on morphine analgesia and tolerance in rats. Forty-eight Wistar Albino male rats were included in the study and the rats were randomly divided into drug and control (saline) groups. To induce morphine tolerance, the rats were injected with 10 mg/kg morphine intraperitoneally for 7 days. After thermal analgesia tests, dorsal root ganglion (DRG) and cortex tissues were isolated. Proapoptotic mediators caspase-3 and 9, total oxidant status (TOS) and total antioxidant status (TAS) and ER stress proteins GRP78/BiP, ATF-6, p-IRE1 and pERK levels were measured by biochemical analysis of tissue homogenates. The findings showed that there was a significant decrease in morphine tolerance in rats administered ACA and 2-APB (p<0.05). In addition, biochemical tests revealed a significant decrease in ER stress proteins, proapoptotic biomarkers and TOS levels and a significant increase in TAS levels in DRG, thalamus and sensory cortex tissues (p<0.05). In conclusion, inhibition of TRPM2 cation channel by ACA and 2-APB reduces morphine tolerance by preventing ER stress and apoptosis. It may be possible to increase the analgesic potential of morphine by combined application with ACA and 2-APB in the clinic, but further experimental and molecular studies are needed.

Geminivirus βV1 protein activates bZIP17/28-mediated UPR signaling to facilitate viral pathogenicity but its activity is attenuated by autophagic degradation in plants

The unfolded protein response (UPR) is a vital cellular pathway that maintains endoplasmic reticulum (ER) homeostasis under conditions of ER stress and is associated with the degradation of misfolded proteins. However, the role of ER-associated degradation in plant-microbe interactions has yet to be explored. In this study, we identified a novel viral protein, βV1, encoded by the tomato yellow leaf curl betasatellite (TYLCCNB), which is localized to the ER and triggers ER aggregation. Transient expression of βV1 in Nicotiana benthamiana induces robust ER stress and activates the bZIP17/28 branch of the UPR signaling pathway. The induction of bZIP17/28 by βV1 is crucial for successful virus infection. Furthermore, we demonstrated that βV1 is unstable in N. benthamiana mesophyll cells, as it is targeted for autophagic degradation. The autophagy-related protein ATG18a, a key component of autophagosomes, participates in the degradation of βV1, thereby exerting an anti-viral role. Taken together, our results reveal a novel function of the βV1 protein and provide the first evidence for involvement of bZIP17/28 and ATG18a in ER-associated autophagic degradation during geminivirus infection. These findings significantly expand our understanding of the arms-race dynamics between plants and viruses.

Exploring proinsulin proteostasis: insights into beta cell health and diabetes

Proinsulin misfolding is central to diabetes. This review examines the cellular mechanisms regulating proinsulin proteostasis in pancreatic β-cells, encompassing genetic factors such as insulin gene mutations, and exploring the roles of endoplasmic reticulum (ER) stress and the unfolded protein response (UPR), ER redox balance, mitochondrial function, and the influence of extrinsic factors. Mutations in the INS gene, particularly those affecting cysteine residues, impair folding and disulfide bond formation, often exhibiting dominant-negative effects on the wild-type proinsulin. The importance of ER quality control mechanisms, including chaperones and oxidoreductases, in facilitating proper folding and degradation of misfolded proinsulin is emphasized. Disruptions in these systems, due to genetic mutations, ER stress, or impaired ER-to-Golgi trafficking, lead to proinsulin accumulation and β-cell dysfunction. The unfolded protein response (UPR), especially the PERK and IRE1α-XBP1 pathways, emerges as a central regulator of protein synthesis and ER stress management. The review also discusses the role of mitochondrial health, ER redox state, and extrinsic factors such as diet and medications in influencing proinsulin proteostasis. Finally, the structural insights from NMR and molecular dynamics simulations are discussedhighlighting the dynamics of misfolding and underscoring the importance of disulfide bonds. These mechanistic insights suggest innovative strategies targeting thiol/disulfide redox systems in cells to mitigate protein misfolding diseases including diabetes.

IRE1 is a promising therapeutic target in pancreatic cancer

[Figure: see text].

Less is better: various means to reduce protein load in the endoplasmic reticulum

The endoplasmic reticulum (ER) is an important organelle that controls the intracellular and extracellular environments. The ER is responsible for folding almost one-third of the total protein population in the eukaryotic cell. Disruption of ER-protein folding is associated with numerous human diseases, including metabolic disorders, neurodegenerative diseases, and cancer. During ER perturbations, the cells deploy various mechanisms to increase the ER-folding capacity and reduce ER-protein load by minimizing the number of substrates entering the ER to regain homeostasis. These mechanisms include signaling pathways, degradation mechanisms, and other processes that mediate the reflux of ER content to the cytosol. In this review, we will discuss the recent discoveries of five different ER quality control mechanisms, including the unfolded protein response (UPR), ER-associated-degradation (ERAD), pre-emptive quality control, ER-phagy and ER to cytosol signaling (ERCYS). We will discuss the roles of these processes in decreasing ER-protein load and inter-mechanism crosstalk.

Beta cell dysfunction occurs independently of insulitis in type 1 diabetes pathogenesis

The loss of insulin secretory function associated with type 1 diabetes (T1D) is attributed to the immune-mediated destruction of beta cells. Yet, at onset of T1D, patients often have a significant beta cell mass remaining while T cell infiltration of pancreatic islets is sporadic. Thus, we investigated the hypothesis that the remaining beta cells in T1D are largely dysfunctional using live human pancreas tissue slices prepared from organ donors with recently diagnosed T1D. Beta cells in slices from donors with T1D had significantly diminished Ca2+ mobilization and insulin secretion responses to glucose. Beta cell function was equally impaired in T cell-infiltrated and non-infiltrated islets. Fixed tissue staining and gene expression profiling of laser-capture microdissected islets revealed significant decreases of proteins and genes in the glucose stimulus secretion coupling pathway. From these data, we posit that functional defects occur in the remaining mass of beta cells during human T1D pathogenesis.

Membrane-tethered SCOTIN condensates elicit an endoplasmic reticulum stress response by sequestering luminal BiP

The endoplasmic reticulum (ER) stress response controls the balance between cellular survival and death. Here, we implicate SCOTIN, an interferon-inducible ER protein, in activating the ER stress response and modulating cell fate through its proline-rich domain (PRD)-mediated cytosolic condensation. SCOTIN overexpression leads to the formation of condensates enveloping multiple layers of the ER, accompanied by morphological signs of organelle stress. Luminal BiP chaperone proteins are sequestered within these SCOTIN condensates, which elicit ER stress responses. The colocalization of luminal BiP with SCOTIN is strictly contingent upon the PRD-mediated condensation of SCOTIN in the cytosolic compartment, closely associated with the ER membrane. The cysteine-rich domain (CRD) of SCOTIN, along with the condensation-prone PRD domain, is required for ER stress induction. We propose that membrane-associated condensation transduces signals across the ER membrane, leading to the induction of BiP assembly and the ER stress response.

The integrated stress response in neurodegenerative diseases

The integrated stress response (ISR) is a conserved network in eukaryotic cells that mediates adaptive responses to diverse stressors. The ISR pathway ensures cell survival and homeostasis by regulating protein synthesis in response to internal or external stresses. In recent years, the ISR has emerged as an important regulator of the central nervous system (CNS) development, homeostasis and pathology. Dysregulation of ISR signaling has been linked to several neurodegenerative diseases. Intriguingly, while acute ISR provide neuroprotection through the activation of cell survival mechanisms, prolonged ISR can promote neurodegeneration through protein misfolding, oxidative stress, and mitochondrial dysfunction. Understanding the molecular mechanisms and dynamics of the ISR in neurodegenerative diseases aids in the development of effective therapies. Here, we will provide a timely review on the cellular and molecular mechanisms of the ISR in neurodegenerative diseases. We will highlight the current knowledge on the dual role that ISR plays as a protective or disease worsening pathway and will discuss recent advances on the therapeutic approaches that have been developed to target ISR activity in neurodegenerative diseases.

Adaptation of Natural Killer Cells to Hypoxia: A Review of the Transcriptional, Translational, and Metabolic Processes

As important innate immune cells, natural killer (NK) cells play an essential role in resisting pathogen invasion and eliminating transformed cells. However, the hypoxic microenvironment caused by disease conditions is an important physicochemical factor that impairs NK cell function. With the increasing prominence of NK cells in immunotherapy, there has been a surge of interest in developing biological means through which NK cells may overcome the inhibition caused by hypoxia in disease conditions. Although the effects of hypoxic conditions in shaping the functions of NK cells have been increasingly recognized and investigated, reviews have been scantly. A comprehensive understanding of how NK cells adapt to hypoxia can provide valuable insights into how the functional capacity of NK cells may be restored. This review focuses on the functional alterations of NK cells in response to hypoxia. It delineates the mechanisms by which NK cells adapt to hypoxia at the transcriptional, metabolic, translational levels. Furthermore, given the complexity of the hypoxic microenvironment, we also elucidated the effects of key hypoxic metabolites on NK cells. Finally, this review discusses the current clinical therapies derived from targeting hypoxic NK cells. The study of NK cell adaptation to hypoxia has yielded new insights into immunotherapy. These insights may lead to development of novel strategies to improve the treatment of infectious diseases and cancer.

(-) - (11R, 12S)-mefloquine ameliorates neuropathic pain by modulating Cx36-ER stress interaction in the pain-related central nervous system in rats

AIMS

To explore the specific molecular and cellular mechanisms of (-) - Mefloquine (one of Mefloquine's enantiomers) in modulating the interaction between Connexin 36 (Cx36) and endoplasmic reticulum stress (ERS) both in rats with CCI-induced neuropathic pain and in tunicamycin-induced ERS cells.

MATERIALS AND METHODS

The authors conducted chronic constriction injury (CCI) in rats to induce neuropathic pain and established the ERS model in SH-SY5Y cells to mimic the stress state after neuropathic pain. The study employed behavioral tests and various molecular biology techniques, including Western blot analysis, cell transfection, and co-immunoprecipitation (co-IP).

KEY FINDINGS

In vivo, we found that (-) - MQ treatment alleviated CCI-induced ERS to regulate the cytoplasmic Cx36 by inhibiting the activation of PERK in spinal cord and ATF-6 in hippocampus, thereby ameliorating neuropathic pain significantly. In vitro, (-) - MQ not only promoted Cx36 synthesis in the ER and inhibited the excessive transport of Cx36 from the ER to the Golgi apparatus, but also interrupted the binding of Cx36 with calmodulin (CaM), which led to diminished junction formation as indicated by the reduced over-stacking of Cx36 on the membrane of the ERS-exposed cells. Together, these findings clarified that (-) - MQ could ameliorate neuropathic pain through modulating Cx36-ERS interactions within pain-associated regions of the central nervous system in CCI rats.

SIGNIFICANCE

This study, for the first time, elucidated the cellular and molecular mechanisms of (-) - MQ in modulating Cx36-ERS interaction in neuropathic pain, thereby providing new therapeutic options for clinical treatment.

Do wolframin, P-glycoprotein, and GRP78/BiP cooperate to alter the response of L1210 cells to endoplasmic reticulum stress or drug sensitivity?

In previous research, we revealed that murine leukemia cells L1210 with induced expression of P-glycoprotein (P-gp, a membrane drug transporter, product of the Abcb1 gene) are better able to withstand endoplasmic reticulum (ER) stress (ERS) than their P-gp negative counterparts. This was associated with increased GRP78/BiP expression and modulation of the expression of several other proteins active in the cellular response to ERS (like CHOP, spliced XBP1, 50-kDa ATF6 protein fragment and others) in P-gp positive cells. Wolframin is an ER transmembrane protein, product of the WFS1 gene whose mutations are associated with Wolfram syndrome. However, this protein is frequently overexpressed in cells undergoing ERS and its expression may accompany changes in the above ERS markers. Therefore, our aim in this work was to investigate wolframin expression in P-gp-negative and P-gp-positive murine leukemia L1210 cells in relation to ERS related proteins in normal or ERS condition. We induced ERS in cells either by blocking N-glycosylation in the ER with tunicamycin or by blocking ER Ca2+-ATPase activity with thapsigargin, as known ER stressors. The results of this paper demonstrated increased wolframin expression in P-gp positive cells compared to P-gp negative cells. Immunoprecipitation experiments revealed the formation of complexes between wolframin and ERS related proteins (PERK, ATF6 and GRP78/BiP), the amount of which varied depending on the presence of the above ER stressors.

Characterization of UGT8 as a monogalactosyl diacylglycerol synthase in mammals

Monogalactosyl diacylglycerol (MGDG) is a major membrane lipid component in plants and is crucial for proper thylakoid functioning. However, MGDG in mammals has not received much attention, partly because of its relative scarcity in mammalian tissues. In addition, the biosynthetic pathway of MGDG in mammals has not been thoroughly analysed, although some reports have suggested that UGT8, a ceramide galactosyltransferase, has the potential to catalyse MGDG biosynthesis. Here, we successfully captured the endogenous levels of MGDG in HeLa cells using liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS)-based lipidomics. Cellular MGDG was completely depleted in CRISPR/Cas9-mediated UGT8 knockout (KO) HeLa cells. Transient overexpression of UGT8 enhanced MGDG production in HeLa cells, and the corresponding cell lysates displayed MGDG biosynthetic activity in vitro. Site-directed mutagenesis revealed that His358 within the UGT signature sequence was important for its activity. UGT8 was localized in the endoplasmic reticulum and activation of the unfolded protein response by membrane lipid saturation was impaired in UGT8 KO cells. These results demonstrate that UGT8 is an MGDG synthase in mammals and that UGT8 regulates membrane lipid saturation signals in cells.

Transmission of unfolded protein response-a regulator of disease progression, severity, and spread in virus infections

The unfolded protein response (UPR) is a cell-autonomous stress response aimed at restoring homeostasis due to the accumulation of misfolded proteins in the endoplasmic reticulum (ER). Viruses often hijack the host cell machinery, leading to an accumulation of misfolded proteins in the ER. The cell-autonomous UPR is the immediate response of an infected cell to this stress, aiming to restore normal function by halting protein translation, degrading misfolded proteins, and activating signaling pathways that increase the production of molecular chaperones. The cell-non-autonomous UPR involves the spreading of UPR signals from initially stressed cells to neighboring unstressed cells that lack the stressor. Though viruses are known modulators of cell-autonomous UPR, recent advancements have highlighted that cell-non-autonomous UPR plays a critical role in elucidating how local infections cause systemic effects, thereby contributing to disease symptoms and progression. Additionally, by utilizing cell-non-autonomous UPR, viruses have devised novel strategies to establish a pro-viral state, promoting virus spread. This review discusses examples that have broadened the understanding of the role of UPR in virus infections and disease progression by looking beyond cell-autonomous to non-autonomous processes and mechanistic details of the inducers, spreaders, and receivers of UPR signals.

Polysulfide and persulfide-mediated activation of the PERK-eIF2α-ATF4 pathway increases Sestrin2 expression and reduces methylglyoxal toxicity

Unfolded protein response (UPR) is activated in cells under endoplasmic reticulum (ER) stress. One sensor protein involved in this response is PERK, which is activated through its redox-dependent oligomerization. Prolonged UPR activation is associated with the development and progression of various diseases, making it essential to understanding the redox regulation of PERK. Sulfane sulfur, such as polysulfides and persulfides, can modify the cysteine residues and regulate the function of various proteins. However, the regulatory mechanism and physiological effects of sulfane sulfur on the PERK-eIF2α-ATF4 pathway remain poorly understood. This study focuses on the persulfidation of PERK to elucidate the effects of polysulfides on the PERK-eIF2α-ATF4 pathway and investigate its cytoprotective mechanism. Here, we demonstrated that polysulfide treatment promoted the oligomerization of PERK and PTP1B in neuronal cells using western blotting under nonreducing conditions. We also observed that l-cysteine, a biological source of sulfane sulfur, promoted the oligomerization of PERK and the knockdown of CBS and 3-MST, two sulfane sulfur-producing enzymes, and reduced PERK oligomerization induced by l-cysteine treatment. Furthermore, the band shift assay and LC-MS/MS studies revealed that polysulfides and persulfides induce PTP1B and PERK persulfidation. Additionally, polysulfides promoted eIF2α phosphorylation and ATF4 accumulation in the nucleus, suggesting that polysulfides activate the PERK-eIF2α-ATF4 pathway in neuronal cells. Moreover, polysulfides protected neuronal cells from methylglyoxal-induced toxicity, and this protective effect was reduced when the expression of Sestrin2, regulated by ATF4 activity, was suppressed. This study identified a novel mechanism for the activation of the PERK-eIF2α-ATF4 pathway through persulfidation by polysulfides and persulfides. Interestingly, activation of this pathway overcame the toxicity of methylglyoxal in dependence on Sestrin2 expression. These findings deepen our understanding of neuronal diseases involving ER stress and UPR disturbance and may inspire new therapeutic strategies.

14-3-3σ restricts YY1 to the cytoplasm, promoting therapy resistance, and tumor progression in colorectal cancer

14-3-3σ functions as an oncogene in colorectal cancer and is associated with therapy resistance. However, the mechanisms underlying these observations are not clear. The results in this report demonstrate that loss of 14-3-3σ in colorectal cancer cells leads to a decrease in tumor formation and increased sensitivity to chemotherapy. The increased sensitivity to chemotherapy is due to a decrease in the expression of UPR pathway genes in the absence of 14-3-3σ. 14-3-3σ promotes expression of the UPR pathway genes by binding to the transcription factor YY1 and preventing the nuclear localization of YY1. YY1, in the absence of 14-3-3σ, shows increased nuclear localization and binds to the promoter of the UPR pathway genes, resulting in decreased gene expression. Similarly, a YY1 mutant that cannot bind to 14-3-3σ also shows increased nuclear localization and is enriched on the promoter of the UPR pathway genes. Finally, inhibition of the UPR pathway with genetic or pharmacological approaches sensitizes colon cancer cells to chemotherapy. Our results identify a novel mechanism by which 14-3-3σ promotes tumor progression and therapy resistance in colorectal cancer by maintaining UPR gene expression.

Cellular takeover: How new world alphaviruses impact host organelle function

Alphavirus replication is dependent on host cell organelles to facilitate multiple steps of the viral life cycle. New world alphaviruses (NWA) consisting of eastern, western and Venezuelan equine encephalitis viruses are a subgroup of alphaviruses associated with central nervous system disease. Despite differing morbidity and mortality amongst these viruses, all are important human pathogens due to their transmission through viral aerosolization and mosquito transmission. In this review, we summarize the utilization of host organelles for NWA replication and the subversion of the host innate immune responses. The impact of viral proteins and replication processes on organelle function is also discussed. Literature involving old world alphaviruses (OWA), such as chikungunya virus and Sindbis virus, is included to compare and contrast between OWA and NWA and highlight gaps in knowledge for NWA. Finally, potential targets for therapeutics or vaccine candidates are highlighted with a focus on host-directed therapeutics.

The endoplasmic reticulum degradation-enhancing α-mannosidase-like protein 3 attenuates the unfolded protein response and has pro-survival and pro-viral roles in hepatoma cells and hepatocellular carcinoma patients

BACKGROUND

Chronic hepatitis B virus (HBV) infection is a major risk for development of hepatocellular carcinoma (HCC), a frequent malignancy with a poor survival rate. HBV infection results in significant endoplasmic reticulum (ER) stress and activation of the unfolded protein response (UPR) signaling, a contributing factor to carcinogenesis. As part of the UPR, the ER-associated degradation (ERAD) pathway is responsible for removing the burden of misfolded secretory proteins, to re-establish cellular homeostasis. Emerging evidence indicates consistent upregulation of ERAD factors, including members of the ER degradation-enhancing alpha-mannosidase-like protein (EDEM) family in infection and various tumor types. However, the significance of this gene expression pattern in HBV-driven pathology is just beginning to be deciphered.

METHODS

In this study we quantified the expression of the ERAD factor EDEM3, in a cohort of HCC patients with and without HBV infection, and validated our results by analysis of publically available transcriptomic and microarray data sets. We performed mechanistic studies in HepaRG cells with modulated EDEM3 expression to address UPR, ERAD, autophagy and apoptosis signaling, and their consequences on HBV infection.

RESULTS

Our work revealed significantly elevated EDEM3 expression in HCC tissues irrespective of HBV infection, while the highest levels were observed in tissues from HBV-infected patients. Investigation of published transcriptomic data sets confirmed EDEM3 upregulation in independent HCC patient cohorts, associated with tumor progression, poor survival prognosis and resistance to therapy. EDEM3-overexpressing hepatic cells exhibited attenuated UPR and activated secretory autophagy, which promoted HBV production. Conversely, cell depletion of EDEM3 resulted in significant ER stress inducing pro-apoptotic mechanisms and cell death.

CONCLUSIONS

We provide evidence of major implications of the ERAD pathway in HBV infection and HCC development and progression. Our results suggest that ERAD activation in HBV-infected cells is a protective mechanism against prolonged ER stress, potentially contributing to establishment of chronic HBV infection and promoting tumorigenesis. Developing specific inhibitors for ERAD factors may be an attractive approach to improve efficiency of current antiviral and anticancer therapies.

Enhancing Tolerance to Combined Heat and Drought Stress in Cool-Season Grain Legumes: Mechanisms, Genetic Insights, and Future Directions

The increasing frequency of concurrent heat and drought stress poses a significant challenge to agricultural productivity, particularly for cool-season grain legumes, including broad bean (Vicia Faba L.), lupin (Lupinus spp.), lentil (Lens culinaris Medik), chickpea (Cicer arietinum L.), grasspea (Lathyrus sativus L.), pea (Pisum sativum L.), and common vetch (Vicia sativa L.). These legumes play a vital role in sustainable agricultural systems due to their nitrogen-fixing ability and high nutritional value. This review synthesizes current knowledge of the impacts and tolerance mechanisms associated with combined heat and drought stresses in these crops. We evaluate physiological and biochemical responses to combined heat and drought stress, focusing on their detrimental effects on growth, development, and yield. Key genetic and molecular mechanisms, such as the roles of osmolytes, antioxidants, and stress-responsive genes, are explored. We also discuss the intricate interplay between heat and drought stress signaling pathways, including the involvement of Ca2+ ions, reactive oxygen species, transcription factor DREB2A, and the endoplasmic reticulum in mediating stress responses. This comprehensive analysis offers new insights into developing resilient legume varieties to enhance agricultural sustainability under climate change. Future research should prioritize integrating omics technologies to unravel plant responses to combined abiotic stresses.

Hepatitis B small surface protein hijacking Bip is initial and essential to promote lipid synthesis

To date, the molecular pathogenic mechanisms between HBsAg and liver metabolic disorders have not been fully understood. To explore the overall effects of HBsAg on liver tissues from HBV transgenic mice, proteome, interactome, and signal pathway analysis were employed to uncover the underlying mechanisms. Bioinformatics analysis of 191 differentially expressed proteins suggested that HBV upregulated the expression of multiple enzymes involved in lipid synthesis, and small HBs (SHBs) caused lipid accumulation in cells. Further studies showed that SHBs bound to binding immunoglobulin protein (Bip), which normally functions in cell homeostasis against the unfolded protein response (UPR) signaling via occupying inositol-requiring enzyme 1 (IRE1). Hijacking Bip by SHBs alleviated the inhibition of post-endoplasmic reticulum (ER) signaling and sequential activation of the IRE1 downstream transcription factors involved in lipid synthesis, such as spliced X-box binding protein 1 (sXBP1) and sterol regulatory element-binding protein 1 (SREBP1), leading to lipid metabolism disorder. The restoration of Bip can alleviate ER stress, and block the sequential post-ER signaling caused by SHBs. This study revealed a new pathway through which SHBs promote lipid disorder, and suggests that Bip may serve as a novel target for intervention in HBV related liver diseases. SIGNIFICANCE: In this study, we found a new pathway promoting the lipid disorder by SHBs through quantitative proteomics studies, and Bip may serve as a novel target for intervention in HBV related liver diseases. These findings highlight a novel role of SHBs in regulating cell lipid metabolism and provide an insight into the relationship between HBV infection and liver fatty disorders, which may serve as a potential therapeutic target for intervention of HBV related liver diseases.

MMP-2 inhibition attenuates ER stress-mediated cell death during myocardial ischemia-reperfusion injury by preserving IRE1α

Endoplasmic reticulum (ER) stress is one of the major events accompanying myocardial ischemia-reperfusion (IR) injury, as hypoxia and oxidative stress disrupt protein folding in the ER. As a result, the unfolded protein response (UPR) is activated through different sensors including inositol-requiring enzyme 1α (IRE1α) and protein kinase R-like ER kinase (PERK). Failure of the UPR to reduce ER stress induces cellular dysfunction. Matrix metalloproteinase-2 (MMP-2) is a ubiquitous protease that is activated intracellularly in response to oxidative stress and partially localizes near the ER. However, its role in ER homeostasis is unknown. We hypothesized that MMP-2 is involved in the regulation of the UPR and ER stress-mediated apoptosis during IR injury. Isolated mouse hearts subjected to IR injury showed impaired recovery of post-ischemic contractile function compared to aerobically perfused controls. Ventricular extracts from IR hearts had higher levels of glucose-regulated protein-78 and protein disulfide isomerase and lower levels of IRE1α and PERK compared to aerobic controls. MMP-2 inhibitors, ARP-100 or ONO-4817, given 10 min before ischemia, improved cardiac post-ischemic recovery and preserved IRE1α level in hearts subjected to 30 min ischemia/40 min reperfusion. IR also increased the levels of CHOP and mitochondrial Bax and caspase-3 and -9 activities, indicating induction of apoptosis, all of which were attenuated by MMP-2 inhibitors, regardless of the reperfusion time. Immunoprecipitation showed an association between MMP-2 and IRE1α in aerobic and IR hearts. During myocardial IR injury MMP-2 may impair the UPR and induce apoptosis by proteolysis of IRE1α. Inhibition of MMP-2 activity protects against cardiac contractile dysfunction in part by preserving IRE1α and preventing the progression to myocardial cell death.

Ursodeoxycholic Acid Alleviates Palmitic Acid-Induced Apoptosis in Bovine Mammary Epithelial Cells

This study investigated the protective effects of ursodeoxycholic acid (UDCA) against PA-induced apoptosis in the MAC-T bovine mammary epithelial cell (bMEC) line by assessing the level of cell viability, oxidative stress indicators, and expression of endoplasmic reticulum (ER) stress markers. MAC-T cells were pretreated with UDCA at 25, 50, and 100 μM before exposure to PA at 300 μM. UDCA was noncytotoxic at these concentrations and significantly improved cell viability, which was reduced by PA. UDCA pretreatment notably decreased PA-induced expression of GRP78, XBP1s, ATF4, and CHOP mRNA, indicating reduced ER stress. Moreover, UDCA substantially lowered PA-induced reactive oxygen species production and dichlorofluorescein fluorescence intensities. Although PA treatment elevated GSSG levels and disrupted redox balance by decreasing both the total GSH/GSSG and reduced GSH/GSSG ratios, UDCA effectively counteracted these effects. Specifically, UDCA reduced PA-induced GSSG levels and restored redox balance by increasing both total and reduced GSH/GSSG ratios. These findings suggest that UDCA mitigates PA-induced apoptosis in MAC-T cells by enhancing redox homeostasis. Therefore, incorporating UDCA into dairy cow feed could help reduce PA-induced cellular stress and improve milk production during periods of negative energy balance.

Baicalein protects against heart failure by improving mitochondrial dysfunction and regulating endoplasmic reticulum stress to reduce apoptosis in vitro and in vivo

OBJECTIVES

Baicalein, a flavonoid derived from the roots of Scutellaria baicalensis Georgi, demonstrates multifarious pharmacological effects due to its high antioxidant activity. However, the latent mechanisms remain insufficiently resolved. In the present research, we evaluated the therapeutic effects of baicalein on isoprenaline (ISO)-induced heart failure and investigated the possible underlying mechanisms.

METHODS

Toxicity was analyzed in zebrafish embryos and mouse atrial myocytes HL-1. The MTT assay was used to evaluate the effectiveness of baicalein. DCFH-DA was used as a fluorescence probe to detect intracellular reactive oxygen species (ROS). Superoxide dismutase (SOD), malondialdehyde (MDA), and glutathione peroxidase (GSH-Px) levels were measured using SOD, MDA and GSH-Px commercial kits. Adult BALB/c mice were randomized into six groups of ten animals each. Cardiac function was analyzed by echocardiographic images. Structural changes were analyzed by hematoxylin & eosin (HE) staining, Masson staining and TUNEL staining. The mechanism of baicalein was investigated by analyzing relative signaling pathways through western blotting.

RESULTS

Our studies show that baicalein both significantly reduces ISO-induced oxidative stress, apoptosis and cardiac fibrosis in vitro and vivo, this phenomenon was related to mitochondrial fusion/fission balance and inhibiting GRP78/CHOP pathway.

CONCLUSIONS

Our results suggested that baicalein controls mitochondrial fusion/fission balance and inhibits GRP78/CHOP pathway, thus exerting therapeutic effects in ISO-induced heart failure in HL-1 cells and BALB/c mice. These results suggested that baicalein may be a potential therapeutic agent for heart failure.