Search Results (627)

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy characterized by therapeutic resistance and poor prognosis, underscoring the need for new therapeutic strategies. Bufalin, a major bioactive constituent of Venenum bufonis, has shown antitumor activity in several cancer types; however, its mechanism of action in PDAC remains incompletely defined. In this study, we investigated the antitumor effects of bufalin in PDAC using in vitro assays, mouse tumor models, and integrative transcriptomic, proteomic, metabolomic, and bioinformatic analyses. Bufalin inhibited PDAC cell viability, clonogenic growth, migration, and tumor progression in vivo. Pharmacological rescue experiments indicated that ferroptosis contributes importantly to bufalin-induced cytotoxicity, although apoptosis- and pyroptosis-related pathways may also be involved. Multi-omics analyses revealed coordinated alterations in calcium homeostasis, endoplasmic reticulum (ER) stress/unfolded protein response (UPR) signaling, and ferroptosis-related metabolic pathways. Further experiments showed that bufalin was associated with disrupted intracellular Ca²⁺ homeostasis, IP₃R-linked ER Ca²⁺ release, activation of PERK/eIF2α/ATF4 signaling, increased ATF3 expression, reduced SLC7A11 and GPX4 expression, glutathione depletion, and enhanced lipid peroxidation. Molecular docking and surface plasmon resonance assays supported an in vitro physical interaction between bufalin and IP₃R1/IP₃R3, while inhibition of ER stress attenuated several bufalin-induced ferroptosis-related phenotypes. Bioinformatic analyses further showed that higher ER stress and ferroptosis signature scores were associated with improved overall survival in PDAC, and concurrent activation of both signatures was linked to the most favorable prognosis. Collectively, these findings support that bufalin suppresses PDAC progression through coordinated ER stress- and ferroptosis-related responses, highlighting ER stress-ferroptosis crosstalk as a potential therapeutic vulnerability in PDAC. Full article

Decidualization in the human endometrium is not merely a hormone-dependent differentiation process; rather, it represents a multilayered adaptive program characterized by the tight integration of immune regulation, metabolic reprogramming, and cellular stress responses. In this review, endoplasmic reticulum (ER) stress and the associated unfolded protein response (UPR) are proposed as central regulatory mechanisms governing this process. Triggered by increased protein synthesis and secretory demand, UPR activation under physiological conditions preserves proteostasis and supports the secretory capacity of stromal cells. In contrast, chronic or dysregulated activation leads to a maladaptive response characterized by apoptosis, inflammation, and metabolic dysfunction. UPR signaling pathways shape immune tolerance through their effects on macrophage polarization, uterine natural killer (uNK) cell function, and T cell balance. At the metabolic level, adenosine monophosphate-activated protein kinase (AMPK) regulates cellular adaptation through bidirectional interactions with mitochondrial function and redox homeostasis. Within this framework, the ER stress–immune–metabolic axis operates not as a linear pathway but as a dynamic network incorporating multiple feedback loops, thereby constituting a critical threshold mechanism that determines the success of decidualization. Disruption of this axis provides a shared mechanistic basis for pathologies such as recurrent implantation failure, pregnancy loss, and preeclampsia. From a therapeutic perspective, agents including chemical chaperones, UPR modulators, AMPK activators, and anti-inflammatory compounds hold translational potential by targeting these pathological feedback circuits. However, key knowledge gaps remain, particularly regarding the cell type-specific and temporal regulation of ER stress, the molecular boundaries defining the transition from adaptive to pathological states, and interspecies differences. Future studies employing single-cell omics approaches and functional in vivo models will be essential to elucidate the dynamic organization of this axis and to enable the development of targeted and personalized therapeutic strategies. Full article

Natural products remain a major source of anticancer agents, yet freshwater organisms are largely unexplored. Building on our previous evidence that planarian mucus exerts cytostatic and cytotoxic effects on cancer cells, we investigated the involvement of endoplasmic reticulum stress and unfolded protein response (UPR) pathways. Mucus-induced cytotoxicity is ROS-dependent and associated with depletion of intracellular reduced glutathione (GSH), not through inhibition of the System Xc⁻ transporter but potentially associated with upregulation of CHAC1, a glutathione-degrading enzyme. Mucus fractionation based on molecular weight identified the high-molecular-weight crude fraction as the one containing the bioactive entity, reproducing the effects of whole mucus. Treatment with this fraction early activates the PERK–ATF4 branch of the UPR, which could be responsible for driving CHAC1 induction. Moreover, ATF4 enhances DDIT3 expression, and activates a compensatory NRF2-dependent antioxidant response. At a later stage mucus also activates the IRE1α–XBP1 axis, with no ATF6 involvement, indicating selective UPR engagement in response to oxidative and lipid stress. Overall, our data are consistent with a potential PERK–ATF4–CHAC1–GSH self-sustaining axis promoting oxidative stress that culminates in cell death, supporting the potential of planarian mucus as a source of pleiotropic bioactive compounds, although the molecular identity of the active component(s) remains still unresolved. Full article

Endoplasmic reticulum (ER) stress and the unfolded protein response (UPR) represent fundamental cellular adaptive mechanisms that maintain protein homeostasis and metabolic balance. Many RNA viruses, particularly flaviviruses such as dengue virus (DENV), Zika virus (ZIKV), West Nile virus (WNV), yellow fever virus (YFV), and Japanese encephalitis virus (JEV), extensively remodel the ER to establish replication compartments and assemble progeny virions. This massive reorganization disrupts ER homeostasis, leading to UPR activation. Emerging evidence reveals that flaviviruses not only trigger but also manipulate the three UPR branches—PERK, IRE1, and ATF6—to optimize viral translation, replication, and egress. In parallel, flavivirus infection profoundly alters host lipid metabolism and promotes dynamic changes in lipid droplets (LDs), key organelles that mediate lipid storage and serve as scaffolds for viral replication and assembly. The UPR intimately connects to LD biogenesis through transcriptional and translational programs mediated by XBP1, ATF4, and ATF6, thereby coupling ER stress responses to lipid remodeling and energy homeostasis. This intricate crosstalk between UPR and LDs creates a metabolic and structural niche favorable for viral replication but detrimental to host cell integrity. This review provides a comprehensive analysis of the molecular mechanisms by which flaviviruses exploit ER stress and the UPR to reprogram lipid metabolism and LD dynamics. We highlight the dual role of UPR signaling in promoting adaptive lipid synthesis and initiating cell death under prolonged stress, discuss recent insights into ER–LD interactions during flavivirus infection, and explore therapeutic opportunities targeting UPR–lipid metabolic pathways as broad-spectrum antiviral strategies. Understanding this interconnected network will advance our knowledge of viral pathogenesis and identify new avenues for host-directed antiviral intervention. Full article

Serglycin (SRGN) has been found overexpressed and secreted in glioblastoma (GBM), associated with tumorigenic signaling and poor prognosis. In this study, we aimed to elucidate the involvement of SRGN in the unfolded protein response (UPR), an oncogenic signaling pathway implicated in protein recycling and cell fate. Herein, we developed stably transduced LN-18^shSCR GBM cells, expressing high levels of SRGN, and SRGN-depleted LN-18^shSRGN cells. We observed significantly attenuated expression and activity of all UPR mediators upon SRGN suppression, in particular PERK, IRE1, ATF6 and downstream effectors. SRGN-expressing cells possessed a constitutively active UPR, as indicated by its active phosphorylation status and accumulated pool of nuclear ATF4 in LN-18^shSCR cells. Constitutive activation of the caspase-dependent apoptotic pathway was apparent in LN-18^shSRGN cells. Induction of endoplasmic reticulum (ER) stress pointed out that LN-18^shSRGN cells were predisposed to ER stress-associated cell death, whereas LN-18^shSCR cells activated adaptive UPR signaling and displayed resistance to apoptosis. The evaluation of TLRs, TNFRs, ILs and NF-kB also underscored that SRGN is essential for their expression and active inflammatory signaling. We concluded that SRGN-expressing cells acquire a pro-survival UPR mechanism, highlighting the novel regulatory role of SRGN in the adaptation and survival of GBM cells. Full article

Climate change has transformed extreme heat from a transient environmental perturbation into a persistent threat that worsens cardiovascular outcomes. Epidemiological studies show a lag between heat exposure and peaks in acute myocardial infarction (AMI) mortality, indicating a subclinical, latent vulnerability. This latent vulnerability likely originates at the level of the microvasculature, as cardiac microvascular endothelial cells (CMECs)—the heart’s primary “thermal sensors”—are uniquely susceptible to proteotoxic stress. The existing literature suggests that this sensitivity may be mediated by thermodynamically gated activation of the activating transcription factor 6 (ATF6) branch of the unfolded protein response (UPR), which could function as a master switch that reprograms endothelial cells from a pro-repair to a maladaptive, anti-angiogenic phenotype. However, this mechanism is derived primarily from preclinical studies and lacks direct validation in humans. The resulting “endothelial memory” is sustained by epigenetic modifications and organelle uncoupling; it persists beyond the initial insult and impairs subsequent neovascularization. As a result, ischemia occurs later in a compromised microenvironment, promoting a fibrosis–conduction mismatch that drives infarct expansion and arrhythmic risk. Thus, the post-exposure latent phase emerges as a novel therapeutic window: Precision targeting of the ER stress–angiogenesis axis during this period offers a focused strategy to protect heat-vulnerable individuals Full article

Yeast models are widely used to study molecular chaperones from diverse organisms, including plants, because of their well-characterized genetics and the conservation of the protein-folding machinery among eukaryotes. Cross-species complementation studies in yeast have yielded valuable insights into conserved biochemical activity and molecular functions that manage protein folding, assembly, and repair during stress. This study evaluated the functional capacity of three potato StBiP isoforms (StBiP1, StBiP2, and StBiP3) to complement the kar2 deletion (kar2Δ) strain under a range of environmental and ER stress conditions. All three StBiPs partially restored colony growth under normal conditions, demonstrating that they are functional orthologs of yeast KAR2 and can support core ER housekeeping functions. Under severe stress, however, the isoforms diverged: StBiP3 most effectively complemented the kar2Δ strain during heat- and chemically induced ER stress, whereas StBiP1 and StBiP2 provided weaker protection. Unfolded protein response (UPR) activation, monitored via HAC1 mRNA splicing, further highlighted isoform-specific differences in how the StBiPs support IRE1-HAC1 signaling under ER stress and oxidative stress. A conserved cysteine in the nucleotide-binding domain, previously implicated in Kar2 redox control, was also critical for StBiP3-mediated protection in yeast, although the same mutation led to different consequences in plant tissues. Together, these findings provide evidence of subfunctionalization among potato BiP isoforms, with StBiP3 emerging as a stress-specialized chaperone that is a promising target for improving ER stress resilience in solanaceous crops. Full article

Alpha-1 antitrypsin deficiency (AATD) is an inherited disorder characterized by intracellular retention of mutant Z (Pi*Z) alpha-1 antitrypsin (AAT) within hepatocytes, resulting in progressive liver disease. Currently, no approved pharmacological therapies exist for AATD-associated hepatic injury. Emerging preclinical evidence indicates that inhibition of mammalian target of rapamycin (mTOR) ameliorates liver pathology in AATD; however, the status of mTOR activity and its regulatory mechanisms under Pi*Z AAT-induced cellular stress remains incompletely understood. In this study, we investigated alterations in mTOR signaling and its upstream regulatory pathways using a gene-edited human hepatocyte model harboring the Pi*Z mutation (Huh7.5Z cells) and a Pi*Z AAT transgenic mouse model. Attenuation of mTORC1 activity was observed in both cellular and murine Pi*Z models. In vitro analyses demonstrated activation of AMP-activated protein kinase (AMPKα), a key inhibitory regulator of mTORC1, accompanied by paradoxical activation of Akt and the unfolded protein response (UPR) branch ATF6α. Pharmacological inhibition of mTOR significantly reduced intracellular Pi*Z AAT accumulation, alleviated ER stress, and suppressed apoptotic signaling through enhancement of autophagy. These findings reveal that hepatocytes adapt to Pi*Z AAT-induced stress through coordinated regulation of mTOR by AMPK, Akt, and ATF6α pathways. This study provides mechanistic insight into metabolic and stress-response signaling in AATD and identifies mTOR modulation as a promising therapeutic strategy for AATD-associated liver disease. Full article

Background: The aminosteroid RM-581 exhibits strong antiproliferative activity against cell lines from more than 10 solid tumor cancers, including some with poor prognoses. However, RM-581’s impact has never been assessed on leukemia. Methods: Cellular responses to RM-581 were evaluated using complementary approaches. Cytotoxicity was quantified using MTS-based viability assays and drug interactions were analyzed according to the Chou-Talalay method. Flow cytometry was employed to assess apoptosis, cell cycle distribution and effects on lymphocytes subpopulations. The transcriptomic profile was investigated by mRNA sequencing to identify differentially expressed genes and associated pathways. Results: Its evaluation on six leukemia cell lines (HL-60, THP-1, JURKAT, K-562, HG-3 and JVM-2) showed that RM-581 efficiently blocked the proliferation of leukemia cells. In healthy peripheral blood lymphocytes, flow cytometry revealed a significant impact on T lymphocytes (CD3+), particularly cytotoxic T cells (CD8+), at 50 µM. In THP-1 cells, an acute monocytic leukemia cell line, RM-581 triggered apoptosis and induced G0/G1 cell cycle arrest, which was confirmed with a transcriptomic analysis of enriched pathways. The role of RM-581 as an endoplasmic reticulum (ER) stress aggravator was confirmed by observing an increase in ER stress markers, such as BIP (GRP-78), CHOP and HERP, and in unfolded protein response (UPR) effectors (PERK, IRE1α and ATF6). Conclusions: This study demonstrates that RM-581 could be a promising candidate to treat leukemia, notably through the induction of ER-stress mediated apoptosis. Full article

The cytotoxic effect of islet amyloid polypeptide (IAPP) misfolding and aggregation has a well-recognized role in the pathogenesis of type 2 diabetes mellitus, mediated by failure of the beta cell’s protein quality control system to rescue the cell from overwhelming proteotoxic stress induced by IAPP aggregates, ultimately leading to apoptosis. A small but growing body of research also links IAPP-mediated proteotoxic stress to the pathogenesis of type 1 diabetes and to the functional decline of transplanted islets. Among the most promising therapeutic approaches under investigation are small organic molecules that may act as direct chemical chaperones to prevent IAPP aggregation, promote the activity of endogenous chaperones, or alter gene networks of the unfolded protein response (UPR) to promote pro-survival rather than pro-apoptotic pathways in response to IAPP-mediated proteotoxic stress. Compounds warranting special attention include 4-phenylbutyrate (PBA), tauroursodeoxycholic acid (TUDCA), and epigallocatechin gallate (EGCG), as each has a growing body of evidence supporting their ability to ameliorate this process, and given that each of these are already known to have good safety profiles in humans, potentially accelerating the timeline to interventional studies. This review explores the evidence for IAPP-mediated proteotoxicity in multiple forms of diabetes, the mechanisms of cytotoxicity at different levels of the cell’s protein quality control systems, how these small organic compounds may act on these processes including new insights on the role of thioredoxin-interacting protein (TXNIP), and the current evidence supporting each of these compounds in mitigating diabetogenesis. Full article

Endoplasmatic reticulum (ER) stress is an imbalance between the load of unfolded proteins and the ability of cellular mechanisms to handle it. Under the influence of this stress, cells activate the unfolded protein response (UPR). The molecular mechanisms of ER stress have been repeatedly linked to metabolic and inflammatory diseases, such as obesity and allergic inflammation. The aim of our study was to investigate if the allergic inflammation in adipocytes affects the expression of UPR pathway genes and Ormdl3 and whether miRNA-665 can modify inflammatory response in adipocytes. We isolated rat preadipocytes and treated them with IL-13 to induce allergic inflammation. Later, we transfected them with miRNA-665 inhibitor. RNA was isolated from adipocytes and analyzed by qPCR. From cell culture medium, we performed an LDH assay and ELISA for secreted IL-6 and TNFα proteins. A comparison between control cells and IL-13-treated cells showed significant differences in the expression of most of the studied UPR pathway genes, Ormdl3 and Bax. Comparing the IL-13-treated cells after miR-665 transfection with non-transfected ones, we observe significant differences only in Ire1α gene. Our research suggests that allergic inflammation induces an adaptive UPR in adipocytes and miR-665 may selectively modify this response, triggering the IRE1/XBP1 axis. Full article

Background/Objectives: This study aimed to compare in vivo cerebral gadolinium (Gd³⁺) accumulation, associated unfolded protein response (UPR), and oxidative stress parameters in rats after exposure to gadolinium-based contrast agents (GBCAs). Methods: This study was designed as a controlled, experimental animal study to evaluate the accumulation of Gd³⁺ in the basal ganglia of rats following the administration of 0.6 mmol/kg gadopentetate dimeglumine (linear) and gadoterate meglumine (macrocyclic). Male Sprague–Dawley rats were exposed to the contrast agents for 24 and 72 h, and then the basal ganglia tissues were collected postmortem. The tissue levels of Gd³⁺ accumulation, activating transcription factor-6 (ATF6), inositol-requiring enzyme-1 (IRE-1), protein kinase RNA-like endoplasmic reticulum kinase (PERK), damage-inducible transcript-3 (DDIT3), total antioxidant status (TAS), and total oxidant status (TOS) were determined. Results: Linear GBCA-treated rats had persistent Gd³⁺ levels over time, whereas a significant reduction from 24 to 72 h was observed in macrocyclic GBCA-treated rats (p < 0.001). PERK, DDIT3, and ATF6 expressions were significantly elevated after linear GBCA exposure (p < 0.05), while no significant increase was observed in the macrocyclic GBCA-treated group. However, IRE-1, TAS, and TOS levels were not significantly different in either group. Conclusions: Linear and macrocyclic GBCAs demonstrated distinct patterns of cerebral Gd³⁺ accumulation and UPR levels in rats. Accordingly, GBCA administration should be reserved for instances where it is necessary, such as when contrast enhancement is clinically required. Full article

During ischemia, endothelial cell integrity is compromised, as a consequence, blood barrier homeostasis is disrupted. Therefore, the structural and functional preservation of endothelial cells is paramount when trying to improve outcomes after ischemic injury. Endoplasmic reticulum (ER) stress is increasingly recognized as a key player in ischemic injury through unfolded protein response (UPR) signalling, and its crosstalk with mitochondrial death pathways. This study provides a cost-effective and straightforward method to delve into the relationship between ER stress and ischemia in human microvascular endothelial cells-1 (HMEC-1). HMEC-1 was exposed to 8 h of oxygen–glucose deprivation (OGD) in glucose-free medium with rapidly induced hypoxia. Hypoxia, oxygen consumption, cell viability, apoptosis, and ER stress markers (BiP/GRP78, PERK, ATF6, IRE1/XBP1s, CHOP) were assessed by RT-qPCR and Western blot. Cell viability decreased by approximately 33% following OGD, while CHOP expression increased ~4-fold, indicating significant ER stress induction. The model enables quantification of metabolic stress (OCR), as well as evaluation of viability loss, membrane integrity, apoptotic commitment, and discrimination between ER stress resolution versus maladaptation. Overall, GasPak EZ Pouch Systems provide a reproducible and practical in vitro platform to study ischemic injury down to the mechanistic details of ER-mitochondria signalling. They give the opportunity to evaluate therapeutic approaches that target ER homeostasis to limit apoptosis and/or recovery of metabolic function after ischemia. This method could allow rapid screening of ER stress-modulating interventions aimed at preserving endothelial barrier function, in various ischemic contexts. Full article

Safety concerns surrounding skin-lightening agents have intensified following chemical leukoderma linked to rhododendrol. Here, we performed an in vitro safety and hazard profiling comparison of raspberry ketone (RK) and a total anthraquinone fraction from Fallopia multiflora var. cillinerve (Polygonum cillinerve) using an immortalized keratinocyte–melanocyte co-culture model (human HaCaT keratinocytes and murine B10.BR melanocytes, 3:1). Rhododendrol and arbutin were included as contextual references. Following viability-guided range finding, cells were exposed for 48 h and evaluated for melanocyte stress and injury, including ROS generation, UPR/ER-stress activation (PERK/eIF2α–ATF4-associated readouts: ATF4, Hmox1, GADD45a; and IRE1 phosphorylation), IL-8-related chemokine output (CXCL1/KC, a murine functional homolog of IL-8), cell-cycle perturbation, and Caspase-3-associated apoptosis. In parallel, targeted LC–MS metabolomics was performed to resolve pathway-level perturbations. High-dose RK elicited a rhododendrol-like in vitro stress/toxicity signature, characterized by elevated ROS, robust UPR engagement, inflammatory chemokine induction, cell-cycle dysregulation, and pro-apoptotic responses; under viability-adjusted conditions, these effects remained more evident than with arbutin. Metabolomics revealed convergent disturbances between RK and rhododendrol, highlighting purine metabolism as a prominent perturbed pathway and suggesting purine-related metabolites as candidate indicators associated with leukoderma-relevant cellular stress in vitro. In contrast, the anthraquinone fraction did not trigger oxidative or ER stress within the tested range and exhibited a more favorable in vitro safety profile, including reduced ROS. Full article

The endoplasmic reticulum (ER) stress response, or unfolded protein response (UPR), is crucial for cellular homeostasis and host defense. Its role in insect vectors of plant pathogens remains poorly understood. This study conducted a comprehensive molecular characterization of three core UPR genes—BiP, IRE1, and XBP1—in Diaphorina citri, the insect vector of the citrus huanglongbing pathogen Candidatus Liberibacter asiaticus (CLas). Expression profiling showed distinct developmental and tissue-specific patterns for these genes. The IRE1-mediated unconventional splicing of XBP1 mRNA was identified in D. citri and predicted across diverse insect pests. A semi-quantitative RT-PCR assay was established to detect this splicing event for monitoring ER stress. Time-course analysis of CLas-infected D. citri revealed an early activation (upregulation of BiP, IRE1, XBP1 transcripts, and increased XBP1 splicing) followed by later suppression of the UPR. Functional studies demonstrated that induction of ER stress with thapsigargin increased CLas titer. RNAi-mediated silencing showed that IRE1 silencing increased CLas proliferation, whereas XBP1 silencing reduced it. These findings provide foundational insights into the ER stress pathway in D. citri and demonstrate that the IRE1-XBP1 branch of the UPR plays a critical role in modulating CLas infection dynamics within its insect vector. Full article