Protein Kinase RNA-like Endoplasmic Reticulum Research Articles

When two signals cross paths: cGAS-STING and ER stress in kidney disease progression.

Previous reports have suggested that both the endoplasmic reticulum (ER) stress and cyclic guanosine monophosphate-adenosine monophosphate synthase-stimulator of interferon genes pathways contribute to the progression of chronic kidney disease; however, the relationship between these 2 pathways in kidney injury has not been fully elucidated. Andrade-Silva etal. revealed that the cyclic guanosine monophosphate-adenosine monophosphate synthase-stimulator of interferon genes pathway can enhance ER stress through the protein kinase R-like ER kinase (PERK)-mediated signaling cascade in kidney tubular epithelial cells and sequentially augment fibrosis during kidney injury. Further studies are needed to elucidate the precise mechanisms by which the cyclic guanosine monophosphate-adenosine monophosphate synthase-stimulator of interferon genes pathway activates PERK-dependent ER stress in kidney tubular epithelial cells post injury.

ADSL promotes autophagy and tumor growth through fumarate-mediated Beclin1 dimethylation.

As an enzyme with a critical role in de novo purine synthesis, adenylosuccinate lyase (ADSL) expression is upregulated in various malignancies. However, whether ADSL possesses noncanonical functions that contribute to cancer progression remains poorly understood. Here, we demonstrate that protein kinase R-like endoplasmic reticulum kinase (PERK) activated by lipid deprivation or ER stress phosphorylates ADSL at S140, leading to an enhanced association between ADSL and Beclin1. Beclin1-associated ADSL produces fumarate, which in turn inhibits lysine demethylase 8-mediated Beclin1 demethylation, resulting in enhanced Beclin1 K117me2, subsequent disruption of the binding of BCL-2 to Beclin1 and elevated autophagy. Blocking the ADSL-Beclin1 axis by knock-in mutation or a cell-penetrating peptide inhibits autophagy induced by lipid deprivation and ER stress and blunts liver tumor growth in mice. Additionally, ADSL pS140-upregulated Beclin1 K117me2 levels are positively correlated with autophagy levels in human hepatocellular carcinoma specimens and poor patient prognosis. These findings uncover the function of ADSL in autophagy regulation and liver tumor development.

Deciphering SPP1-related macrophage signaling in the pathogenesis of intervertebral disc degeneration

This study delved into the molecular mechanisms underlying mechanical stress-induced intervertebral disc degeneration (msi-IDD) through single-cell and high-throughput transcriptome sequencing in mouse models and patient samples. Results exhibited an upsurge in macrophage presence in msi-IDD intervertebral disc (IVD) tissues, with secreted phosphoprotein 1 (SPP1) identified as a pivotal driver exacerbating degeneration via the protein kinase RNA-like endoplasmic reticulum kinase/ activating transcription factor 4/ interleukin-10 (PERK/ATF4/IL-10) signaling axis. Inhibition of SPP1 demonstrated promising outcomes in mitigating msi-IDD progression in both in vitro and in vivo models. These findings underscore the therapeutic promise associated with the modulation of the PERK signaling pathway in IDD, shedding light on the pathogenesis of msi-IDD and proposing a promising avenue for intervention strategies.Graphical abstract1) Macrophage Regulation in IDD: SPP1 activates the PERK/ATF4/IL-10 signaling axis in macrophages, increasing IL-10 production, essential for inhibiting msi-IDD progression.2) Effective Intervention: Inhibition of SPP1 in macrophages shows potential for therapeutic intervention, significantly mitigating msi-IDD progression in mouse models.3) Mechanical Stress Insights: Highlights the critical role of mechanical stress in intervertebral disc degeneration, establishing a link between macrophage activity and IDD pathogenesis through advanced molecular profiling.

Betacoronaviruses Differentially Activate the Integrated Stress Response to Optimize Viral Replication in Lung-Derived Cell Lines.

The betacoronavirus genus contains five of the seven human coronaviruses, making it a particularly critical area of research to prepare for future viral emergence. We utilized three human betacoronaviruses, one from each subgenus-HCoV-OC43 (embecovirus), SARS-CoV-2 (sarbecovirus), and MERS-CoV (merbecovirus)-, to study betacoronavirus interactions with the PKR-like ER kinase (PERK) pathway of the integrated stress response (ISR)/unfolded protein response (UPR). The PERK pathway becomes activated by an abundance of unfolded proteins within the endoplasmic reticulum (ER), leading to phosphorylation of eIF2α and translational attenuation. We demonstrate that MERS-CoV, HCoV-OC43, and SARS-CoV-2 all activate PERK and induce responses downstream of p-eIF2α, while only SARS-CoV-2 induces detectable p-eIF2α during infection. Using a small molecule inhibitor of eIF2α dephosphorylation, we provide evidence that MERS-CoV and HCoV-OC43 maximize viral replication through p-eIF2α dephosphorylation. Interestingly, genetic ablation of growth arrest and DNA damage-inducible protein (GADD34) expression, an inducible protein phosphatase 1 (PP1)-interacting partner targeting eIF2α for dephosphorylation, did not significantly alter HCoV-OC43 or SARS-CoV-2 replication, while siRNA knockdown of the constitutive PP1 partner, constitutive repressor of eIF2α phosphorylation (CReP), dramatically reduced HCoV-OC43 replication. Combining GADD34 knockout with CReP knockdown had the maximum impact on HCoV-OC43 replication, while SARS-CoV-2 replication was unaffected. Overall, we conclude that eIF2α dephosphorylation is critical for efficient protein production and replication during MERS-CoV and HCoV-OC43 infection. SARS-CoV-2, however, appears to be insensitive to p-eIF2α and, during infection, may even downregulate dephosphorylation to limit host translation.

Endoplasmic reticulum stress causes long bone shortening in P4hbC402R/+ mice: A mouse model exhibiting significant features of cole-carpenter syndrome driven by P4HB mutations.

Cole-Carpenter syndrome (CCS) is a rare autosomal-dominant genetic disease characterized by craniosynostosis, ocular proptosis, hydrocephalus, distinctive facial features, and bone fragility. Previous cases of CCS are associated with genetic variations in P4HB, which encodes the protein disulfide isomerase (PDI), a key enzyme in protein folding. Patients with CCS caused by P4HB mutations often present with short stature, limb deformities, and abnormal epiphyseal plates. However, the underlying mechanisms are largely unknown. To investigate this, a mouse model expressing the P4hbC402R mutation (corresponding to P4HBC400R in humans) was generated. Although the mouse model did not exhibit craniofacial bone defects or brittle bone phenotypes, it did show significantly shortened long bones-a prominent characteristic of P4HB-induced CCS. This was due to impaired proliferation and delayed hypertrophy of growth plate chondrocytes. Mutant PDI was found to accumulate abnormally in the endoplasmic reticulum (ER), and in vitro experiments revealed defects in both the catalytic and chaperone activities of mutant PDI. In addition, we observed enhanced ER stress and activation of the PKR-like ER kinase (PERK) pathway in P4hbC402R/+ chondrocytes. Inhibition of ER stress mitigated PERK activation, alleviated defective chondrocyte proliferation and differentiation, thereby rescuing bone length. Taken together, enhanced ER stress and the activation of the PERK, potentially initiated by the malfunctioning of PDIC402R or its abnormal accumulation within the ER, or both, lead to compromised chondrocyte proliferation and differentiation in mice, and ultimately stunts mice growth. This provides new insights into the pathogenesis of P4HB-dominated CCS and offers potential therapeutic targets.

GRP78: A New Promising Candidate in Colorectal Cancer Pathogenesis and Therapy.

Colorectal cancer (CRC) is a significant global health challenge, marked by varying incidence and mortality rates across different regions. The pathogenesis of CRC involves multiple stages, including initiation, promotion, progression, and metastasis, influenced by genetic and epigenetic factors. The chaperone protein glucose-regulated protein 78 (GRP78), crucial in regulating the unfolded protein response (UPR) during endoplasmic reticulum (ER) stress, plays a pivotal role in CRC pathogenesis. This review discusses the expression profile of GRP78 in CRC, highlighting its potential as a prognostic biomarker and its role in modulating the cellular mechanisms of CRC, including ER response regulation, cell proliferation, migration and invasion. The complex molecular interactions of GRP78 with key signaling pathways such as protein kinase B (Akt), Wnt, protein kinase R-like ER kinase (PERK), vascular endothelial growth factor (VEGF), and Kirsten rat sarcoma virus (Kras) are explored, elucidating its contributions to tumor survival, proliferation, invasion, and chemoresistance. GRP78's involvement in autophagy, glycolysis, and immune regulation further underscores its importance in CRC progression. The review also covers the therapeutic potential of targeting GRP78 in CRC, examining various natural products like curcumin, epigallocatechin gallate (EGCG), and aloe-emodin, which modulate GRP78 expression and activity. Additionally, GRP78's role in mediating resistance to chemotherapeutic agents like 5-fluorouracil (5-FU) and oxaliplatin is discussed, emphasizing its significance in the development of resistance mechanisms in CRC. In conclusion, GRP78 emerges as a central player in CRC pathogenesis and a promising target for therapeutic interventions aimed at improving treatment outcomes and overcoming chemoresistance in colorectal cancer.

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.

Salivary adenoid cystic carcinoma-derived α2,6-sialylated extracellular vesicles increase vascular permeability by triggering ER-stress in endothelial cells and promote lung metastasis.

Salivary adenoid cystic carcinoma (SACC) tends to metastasize to the lungs in the early stages of the disease. Factors secreted by the primary tumor can induce the formation of a supportive microenvironment in distant organs prior to metastasis, a process known as pre-metastatic niche (PMN) formation. Extracellular vesicles (EVs) participate in PMN formation. In this study, α2,6-sialylation of EVs derived from SACC cells with high metastatic potential increased vascular permeability, thereby facilitating tumor metastasis to the lungs. Mechanistic studies indicated that EV α2,6-sialylation triggers protein kinase R-like endoplasmic reticulum kinase (PERK)-eukaryotic initiation factor 2α (eIF2α)-dependent activation of endoplasmic reticulum (ER) stress in the endothelium, leading to the disruption of vascular endothelial cadherin membrane expression. Sialidase or an ER stress inhibitor rescued vascular permeability induced by SACC EVs, which decreased the number of SACC cells extravasating into the lungs both in vitro and in vivo. This study identified a critical role of α2,6-sialylation of SACC EVs in lung metastasis. The findings indicate that EV α2,6-sialylation-induced ER stress in endothelial cells might be a therapeutic target for preventing SACC lung metastasis.

Quercetin Alleviates All-Trans-Retinal-Induced Photoreceptor Apoptosis and Retinal Degeneration by Inhibiting the ER Stress-Related PERK Signaling.

All-trans-retinal (atRAL)-induced photoreceptor atrophy and retinal degeneration are hallmark features of dry age-related macular degeneration (AMD) and Stargardt disease type 1 (STGD1). The toxicity of atRAL is closely related to the generation of reactive oxygen species (ROS). Quercetin, a natural product, is known for its potent antioxidant properties; however, its effects in mitigating atRAL-mediated retinal damage remains unclear. This study investigated the protective effects of quercetin against atRAL-induced photoreceptor damage. Using atRAL-loaded 661W photoreceptor cells, we evaluated cell viability, ROS generation, and endoplasmic reticulum (ER) stress under quercetin treatment. Quercetin significantly restored the cell viability (to 70%) and reduced ROS generation in atRAL-treated 661W cells. Additionally, Western blot analysis demonstrated that quercetin mitigated protein kinase RNA-like ER kinase (PERK) signaling, preventing ER stress-induced apoptosis. Importantly, in Abca4-/-Rdh8-/- mice, an animal model of light-induced atRAL accumulation in the retina, quercetin treatment effectively alleviated light-exposed photoreceptor atrophy and retinal degeneration by attenuating PERK signaling. Thus, quercetin protected photoreceptor cells from atRAL-induced damage by inhibiting ROS generation and PERK signaling, which suggests its potential as a therapeutic agent for atRAL-related retinal degeneration.

STING facilitates the development of radiation-induced lung injury via regulating the PERK/eIF2α pathway.

Radiation-induced lung injury (RILI) is one of the serious adverse reactions of thoracic radiotherapy, which largely limits the dose and therapeutic effect of radiotherapy. The underlying mechanism has not been elucidated. RILI is characterized by an acute inflammatory response, and stimulator of interferon genes (STING) has been reported to play an important role in regulating inflammation and innate immune activation. However, its role in RLLI, remains unclear. Here, we reported the potential therapeutic effect of STING inhibitor H-151 on RILI. C57BL/6J mice were exposed to 20 Gy whole-thorax irradiation and H-151 was injected intraperitoneally from the day of irradiation for 4 weeks. The degree of RILI was then assessed. To further explore the mechanism of STING in RILI, the supernatant of irradiated lung epithelial cell MLE-12 was co-cultured with embryonic fibroblast cell NIH/3T3. The cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS)-STING pathway is abnormally activated in irradiated mouse lung tissues. The early application of STING inhibitor significantly alleviated radiation-induced inflammatory cell infiltration and pro-inflammatory cytokine release in lung tissue, as well as the degree of fibrosis in the late stage. The amount of double-stranded DNA (dsDNA) in the supernatant of irradiated MLE-12 cells was abnormally increased, and the epithelial-derived dsDNA could promote the transformation of fibroblasts into myofibroblasts. Mechanistically, STING could mediate the activation of fibroblasts to myofibroblasts via the PKR-like endoplasmic reticulum kinase (PERK)-eukaryotic initiation factor 2α (eIF2α) pathway. Our study focused on the activation of cGAS-STING signaling pathway in RILI, and inhibition of STING significantly ameliorated RILI in mice. STING mediated the effect of radiation-induced dsDNA release to stimulate the activation of inflammatory response, and STING restriction significantly delayed the fibrosis process through the PERK-eIF2α pathway, suggesting that STING intervention may pave a new avenue for the treatment of RILI.

Adjuvant alum regulates the eIF2a-GATA3 axis in CD4+ T cells to influence allergen immunotherapy.

Allergen-specific immunotherapy (AIT) is an aetiology-targeting therapy for allergic diseases. The therapeutic mechanism of AIT is not fully understood yet. Endoplasmic reticulum stress is associated with the pathogenesis of allergic disorders. This study aims to elucidate the effects of AIT on suppressing allergic response through regulating endoplasmic reticulum stress. In this study, patients with perennial allergic rhinitis were recruited. AIT was conducted for the patients. An allergic rhinitis (AR) mouse model was established with mite extracts as allergens. We found that AIT modulated the endoplasmic reticulum stress status in peripheral CD4+ T cells in patients with allergic rhinitis. The intensity of endoplasmic reticulum stress associated the PERK (protein kinase RNA-like endoplasmic reticulum kinase)-eIF2a (eukaryotic translation initiation factor 2a) axis in CD4+ T cells was upregulated by AIT, which was closely associated with the improvement in allergic rhinitis response after AIT. eIF2a interacted with GATA3 to downregulate the IL4 gene transcription in CD4+ T cells. High doses of aluminium hydroxide (alum) in AIT vaccines enhanced the activity of XBP1 to suppress eIF2a in CD4+ T cells. AIT containing a low dose of alum effectively mitigated the experimental allergic rhinitis, while the AIT without alum or a high dose of alum exacerbated the experimental allergic rhinitis. In conclusion, the alum adjuvant in allergen vaccines can regulate the activity of eIF2a to regulate the expression of Th2 cytokines in CD4+ T cells. Manipulating the alum dose in AIT vaccines has the potential to enhance the therapeutic effects of AIT.

Abstract 4134426: Targeting the TRIM29-PERK signaling axis for treating viral myocarditis

Introduction: Viral myocarditis is an inflammatory disease of the myocardium that significantly contributes to sudden death in children and young adults. The COVID-19 pandemic underscores the critical need to understand the pathogenesis and develop effective treatment strategies for viral myocarditis. Methods: To investigate the role of the novel E3 ligase TRIM29 in viral myocarditis, we used wild-type and TRIM29 knockout mice infected with coxsackievirus B3 (CVB3) and encephalomyocarditis virus (EMCV), to induce the myocarditis. Additionally, wild-type mice infected with CVB3 were treated with the protein kinase RNA-like endoplasmic reticulum kinase (PERK) inhibitor GSK2656157 or a DMSO control to evaluate potential therapeutic interventions. Mice survival and heart function were monitored using transthoracic echocardiography, and hearts were harvested for histological and immunohistochemical analysis. Techniques including real-time PCR, western blotting, co-immunoprecipitation, enzyme-linked immunoassay, flow cytometry, over-expression, and knockdown were employed to elucidate the pathogenic mechanisms by which TRIM29 regulates the endoplasmic reticulum stress response after viral infection. Results: We found that TRIM29 was highly induced by cardiotropic viruses, including CVB3 and EMCV, and promoted PERK-mediated endoplasmic reticulum (ER) stress, apoptosis, and reactive oxygen species (ROS) responses, which restricted viral replication in cardiomyocytes in vitro . TRIM29 deficiency protected mice from viral myocarditis by enhancing cardiac antiviral functions and reducing PERK-mediated inflammation and immunosuppressive cells in vivo . Mechanistically, TRIM29 interacted with PERK to catalyze the SUMOylation of PERK, maintaining its stability and thereby promoting PERK-mediated signaling pathways. Furthermore, we demonstrated that the PERK inhibitor GSK2656157 mitigated viral myocarditis by disrupting the TRIM29-PERK interaction, which improved cardiac function, enhanced cardiac antiviral responses, and reduced inflammation and immunosuppressive cells in vivo . Conclusions: Our findings provide the first evidence that the TRIM29-PERK signaling axis can be targeted for the treatment of viral myocarditis. This suggests that targeting the TRIM29-PERK axis could effectively mitigate viral myocarditis and associated cardiovascular diseases.

Grass Carp Reovirus (GCRV) infection activates the PERK-eIF2α pathway to promote the viral replication

Grass carp reovirus (GCRV) belongs to the genus Aquareovirus and is responsible for causing serious hemorrhagic disease in grass carp (Ctenopharyngodon idella), characterized by high mortality rates. Numerous animal viruses have been shown to activate endoplasmic reticulum stress (ERS). However, the potential for GCRV infection to induce ERS and its implications for viral infection remain unclear. In this study, we demonstrated that GCRV infection induces ERS, activates the protein kinase R-like ER kinase (PERK) pathway, and inhibits both the inositol-requiring enzyme 1 (IRE1) and activating transcription factor 6 (ATF6) pathways within the unfolded protein response (UPR). Additionally, we modulated the levels of ERS and UPR pathways in CIK cells through drug treatment and small interfering RNAs (siRNAs). Our findings revealed that the onset of ERS accelerated GCRV infection, while the ATF6 and IRE1 pathways within the UPR negatively regulated GCRV infection. Conversely, the PERK pathway facilitated GCRV infection. Furthermore, we showed that GCRV infection induced oxidative stress, with the production of reactive oxygen species (ROS) being positively regulated by the PERK pathway and the downstream gene endoplasmic reticulum oxidoreductase-1α (ERO1α). Notably, ROS promoted GCRV infection. Collectively, our findings indicate that GCRV infection activates ERS, which in turn promotes viral infection through the PERK-ERO1α-ROS signaling pathway. Thus, the PERK pathway may serve as a novel antiviral target for the prevention of GCRV infection.

The critical role of endoplasmic reticulum stress and the stimulator of interferon genes (STING) pathway in kidney fibrosis

Endoplasmic reticulum (ER) stress is a condition in which the ER is overwhelmed and unable to manage its protein load properly. The precise activation mechanisms and role of ER stress in kidney disease remain unclear. To study this, we performed unbiased transcriptomics analysis to demonstrate ER stress in kidneys of patients with chronic kidney disease and in mouse models of acute and chronic kidney injury (cisplatin and unilateral ureteral obstruction and reanalyzed previously published data on folic acid and mitochondrial transcription factor A(TFAM) knockout mice). Inhibiting the protein kinase RNA-like ER kinase (PERK) arm of ER stress but not activating transcription factor 6 or inositol-requiring enzyme 1, protected mice from kidney fibrosis. The stimulator of interferon genes (STING) was identified as an important upstream activator of ER stress in kidney tubule cells. STING and PERK were found to physically interact, and STING agonists induced PERK activation in kidney tubule cells. Mice with a STING activating mutation presented with ER stress and kidney fibroinflammation. We also generated mice with a tubule specific STING deletion that were resistant to ER stress and kidney fibrosis. Human kidney spatial transcriptomics highlighted a spatial correlation between STING, ER stress and fibrotic gene expression. Thus, our results indicate that STING is an important upstream regulator of PERK and ER stress in tubule cells during kidney fibrosis development.

Short-term Uridine Treatment Alleviates Endoplasmic Reticulum Stress via Regulating Inflammation and Oxidative Stress in Lithium-Pilocarpine Model of Status Epilepticus

Status Epilepticus (SE) leads to the development of epilepsy with the contribution of Endoplasmic Reticulum (ER) stress. Uridine, a pyrimidine nucleoside, has been shown to have neuroprotective and antiepileptogenic effects in animal models. This study aimed to determine whether uridine ameliorates ER stress and apoptosis following epileptogenic insult. Secondly, this study aimed to establish the effect of uridine on inflammatory and oxidative stress parameters that contribute to ER stress. Status epilepticus was induced using lithium-pilocarpine in adult male Sprague-Dawley rats. Following SE termination, rats were treated with uridine, 4-phenylbutyric acid (4-PBA), or saline twice daily for 48 h. Expressions of hippocampal glucose-regulated protein 78 (GRP78), Inositol- Requiring Protein 1 (IRE1α), Protein kinase RNA-like Endoplasmic Reticulum Kinase (PERK), and C/EBP Homologous Protein (CHOP) were determined by western blotting 48 h after SE. Uridine's effects on apoptosis, inflammation or oxidation were evaluated by analyses of cleaved caspase-3 and poly(ADP-ribose) polymerase 1 (PARP1) protein expressions or pro-inflammatory cytokine levels or levels of oxidative stress markers, respectively. Expressions of all ER stress-related proteins significantly increased 48 h after SE. Uridine treatment markedly decreased GRP78, IRE1α, and CHOP levels. A decrease in the PERK level was observed following the administration of 4-PBA; however, uridine had no effect. Cleaved caspase-3 and PARP1 levels were increased in the SHAM group, while uridine and 4-PBA treatment effectively decreased their expressions. Treatment with uridine significantly reduced Myeloperoxidase (MPO) and Malondialdehyde (MDA) levels while tending to increase Catalase (CAT) and Glutathione Peroxidase (GPx) levels. Uridine treatment also significantly attenuated levels of TNF-α and IL-1β, the pro-inflammatory cytokines, which increased 48 h post-SE. Our data indicate that uridine alleviates ER stress after SE. This effect may be attributed to the regulation of inflammation and oxidative stress. Uridine shows promise as a potential preventive agent for epilepsy.

Endoplasmic Reticulum Stress Nano-Orchestrators for Precisely Regulated Immunogenic Cell Death as Potent Cancer Vaccines.

Dying tumor cells regulated by immunogenic cell death (ICD) inducers are promising candidates for cancer vaccine development because of their comprehensive antigen spectrum. However, their limited immunogenicity and potential tumorigenicity hinder clinical translation. To address these challenges, a nano-orchestrator is developed that targets the endoplasmic reticulum (ER) stress, a critical pre-ICD event, to optimize the "precise dose" of ER stress. Using a clinical-range irradiation fluence (50‒200 J cm-2) with an 808 nm laser, the release of damage associated molecular patterns (DAMPs) and antigens are precisely regulated. A fluence of 150 J cm-2 (2 W cm-2 for 75 s) increases dendritic cell maturation and antitumor T cell proliferation, providing valuable clinical insights. The ER stress nano-orchestrator enhances both adjuvanticity and antigenicity via the protein kinase R-like endoplasmic reticulum kinase (PERK)-C/EBP homologousprotein (CHOP) pathway to regulate ICD-induced DAMPs and promote tumor cell apoptosis. These optimized ER stress phototherapeutic dying tumor cells can serve as prophylactic vaccines, achieving a remarkable 100% success rate against tumor rechallenge in vivo. Additionally, the nano-orchestrator shows the potential to develop in situ therapeutic tumor vaccines when combined with anti-PD-L1 treatment, providing important insights into enhancing the efficacy of immune checkpoint regulators by modulating endogenous immune responses.

Potential ameliorative effect of Dapagliflozin on systemic inflammation-induced cardiovascular injury via endoplasmic reticulum stress and autophagy pathway.

Dapagliflozin (DPG) is a sodium-glucose cotransporter-2 inhibitor and is used in the treatment of diabetes. In this study, we aimed to investigate the effect of DPG on cardiotoxicity caused by systemic inflammation via endoplasmic reticulum (ER) stress and autophagy. Four groups of thirty-two Wistar Albino rats were created: Control (1ml oral physiological saline for five days and intraperitoneal saline on the 5th day), LPS (1ml oral physiological saline for five days and intraperitoneal 5mg/kg of LPS on the 5th day), LPS + DPG (10mg/kg of DPG orally for five days and 5mg/kg of LPS intraperitoneally on the 5th day), and DPG (10mg/kg of DPG orally for five days and 5mg/kg of SF intraperitoneally on the 5th day). Histopathological and immunohistochemical analyses were performed on heart and aorta tissues. ER stress and autophagy gene markers in heart tissues were evaluated by RT-qPCR. Oxidative stress in heart tissues and serum cardiac enzymes were analyzed by spectrophotometric method. The heart and aortic tissues of the LPS group showed increased expressions of Tumor Necrosis Factor-α (TNF-α) and Caspase-3 (Cas-3), along with mild hyperemia, slight inflammatory cell infiltrations, and myocardial cell damage. The heart tissues also showed genetically increased expressions of include binding immunoglobulin protein (BiP/ GRP78), protein kinase RNA-like ER Kinase (PERK), inositol-requiring enzyme 1 (IRE-1), activating transcription factors 4 (ATF-4), activating transcription factors 4 (ATF6), C/EBP homologous protein (CHOP), and BECLIN 1. Furthermore, Creatine kinase-MB (CK-MB) and Lactate dehydrogenase (LDH) levels in blood tissue significantly increased, according to biochemical analysis. With DPG therapy, all of these findings were reversed. In conclusion, DPG protects against the cardiotoxic effect of systemic inflammation with its antioxidant and anti-inflammatory properties by regulating ER stress and autophagy pathways.

Sodium-Glucose Cotransporter 2 (SGLT2) Inhibitors: Guardians against Mitochondrial Dysfunction and Endoplasmic Reticulum Stress in Heart Diseases.

Sodium-glucose cotransporter 2 (SGLT2) inhibitors are an innovative class of antidiabetic drugs that provide cardiovascular benefits to both diabetic and nondiabetic patients, surpassing those of other antidiabetic drugs. Although the roles of mitochondria and endoplasmic reticulum (ER) in cardiovascular research are increasingly recognized as promising therapeutic targets, the exact molecular mechanisms by which SGLT2 inhibitors influence mitochondrial and ER homeostasis in the heart remain incompletely elucidated. This review comprehensively summarizes and discusses the impacts of SGLT2 inhibitors on mitochondrial dysfunction and ER stress in heart diseases including heart failure, ischemic heart disease/myocardial infarction, and arrhythmia from preclinical and clinical studies. Based on the existing evidence, the effects of SGLT2 inhibitors may potentially involve the restoration of mitochondrial biogenesis and alleviation of ER stress. Such consequences are achieved by enhancing adenosine triphosphate (ATP) production, preserving mitochondrial membrane potential, improving the activity of electron transport chain complexes, maintaining mitochondrial dynamics, mitigating oxidative stress and apoptosis, influencing cellular calcium and sodium handling, and targeting the unfolded protein response (UPR) through three signaling pathways including inositol requiring enzyme 1α (IRE1α), protein kinase R like endoplasmic reticulum kinase (PERK), and activating transcription factor 6 (ATF6). Therefore, SGLT2 inhibitors have emerged as a promising target for treating heart diseases due to their potential to improve mitochondrial functions and ER stress.

Enhanced endoplasmic reticulum stress signaling disrupts porcine sertoli cell function in response to Bisphenol A exposure

Bisphenol A (BPA), a pervasive substance in our daily lives and livestock excreta, poses significant threats due to its infiltration into foods and water sources. BPA has adverse impacts on male reproductive function, particularly affecting the critical Sertoli (ST) cells that play a pivotal role in the process of spermatogonia differentiating into spermatozoa. In this study, we examined the prevalence of BPA within the pig industry and delved into the impact of BPA exposure on the motility of boar sperm, the function of pig ST cells, as well as the underlying molecular mechanisms involved. This study revealed spatial disparities in the global distribution of BPA and its analogue contamination, utilizing data compiled from 130 comprehensive studies. The average concentration of BPA found in pig feed ranges from 9.7 to 47.9 μg/kg, while in serum, it averages between 55.1 and 75.6 ng/L. The BPA concentration in feed exhibits a negative correlation with sperm viability and the percentage of progressive motile spermatozoa. Exposure to BPA reduced sperm motility in boar and ST cell activity at both 6 and 24 h. The transcriptome analysis revealed that, compared to untreated control cells, endoplasmic reticulum stress (ERS)-related genes were upregulated in ST cells exposed to BPA at 6 and 24 h. This activation of ERS in ST cells was mediated by receptor protein kinase RNA-like endoplasmic reticulum kinase (PERK), inositol-requiring protein-1α (IRE1α), and activating transcription factor 6 (ATF6). Additionally, BPA exposure triggered oxidative stress and a proinflammatory response mediated by the transcription factor NF-κB, accompanied by an increase in downstream proinflammatory cytokines. BPA exposure also led to apoptosis in ST cells and upregulated the expression levels of pro-apoptosis proteins. However, inhibiting ERS activity with 4-PBA attenuated the BPA-induced inflammatory response and apoptosis in ST cells. Our findings suggest that BPA induced apoptosis and inflammatory response in porcine ST cells through persistent activation of ERS, thereby compromising the normal function of these cells.

Genetic knock-in of EIF2AK3 variants reveals differences in PERK activity in mouse liver and pancreas under endoplasmic reticulum stress

Common single-nucleotide variants (SNVs) of eukaryotic translation initiation factor 2 alpha kinase 3 (EIF2AK3) slightly increase the risk of disorders in the periphery and the central nervous system. EIF2AK3 encodes protein kinase RNA-like endoplasmic reticulum kinase (PERK), a key regulator of ER stress. Three exonic EIF2AK3 SNVs form the PERK-B haplotype, which is present in 28% of the global population. Importantly, the precise impact of these SNVs on PERK activity remains elusive. In this study, we demonstrate that PERK-B SNVs do not alter PERK expression or basal activity in vitro and in the novel triple knock-in mice expressing the exonic PERK-B SNVs in vivo. However, the kinase activity of PERK-B protein is higher than that of PERK-A in a cell-free assay and in mouse liver homogenates. Pancreatic tissue in PERK-B/B mice also exhibit increased susceptibility to apoptosis under acute ER stress. Monocyte-derived macrophages from PERK-B/B mice exhibit higher PERK activity than those from PERK-A/A mice, albeit with minimal functional consequences at acute timepoints. The subtle PERK-B-driven effects observed in liver and pancreas during acute stress implicate PERK as a contributor to disease susceptibility. The novel PERK-B mouse model provides valuable insights into ER stress-induced PERK activity, aiding the understanding of the genetic basis of disorders associated with ER stress.