Role Of Endoplasmic Reticulum Research Articles

Unraveling the Connection: Pain and Endoplasmic Reticulum Stress.

Pain is a complex and multifaceted experience. Recent research has increasingly focused on the role of endoplasmic reticulum (ER) stress in the induction and modulation of pain. The ER is an essential organelle for cells and plays a key role in protein folding and calcium dynamics. Various pathological conditions, such as ischemia, hypoxia, toxic substances, and increased protein production, may disturb protein folding, causing an increase in misfolding proteins in the ER. Such an overload of the folding process leads to ER stress and causes the unfolded protein response (UPR), which increases folding capacity in the ER. Uncompensated ER stress impairs intracellular signaling and cell function, resulting in various diseases, such as diabetes and degenerative neurological diseases. ER stress may be a critical universal mechanism underlying human diseases. Pain sensations involve the central as well as peripheral nervous systems. Several preclinical studies indicate that ER stress in the nervous system is enhanced in various painful states, especially in neuropathic pain conditions. The purpose of this narrative review is to uncover the intricate relationship between ER stress and pain, exploring molecular pathways, implications for various pain conditions, and potential therapeutic strategies.

Zoledronic Acid Accelerates ER Stress-Mediated Inflammation by Increasing PDE4B Expression in Bisphosphonate-Related Osteonecrosis of the Jaw.

Long-term administration of bisphosphonates can lead to a significant side effect known as bisphosphonate-related osteonecrosis of the jaw (BRONJ). Although macrophage-mediated inflammation has been established as an important factor in BRONJ, the underlying mechanism remains elusive. In the current study, the roles of endoplasmic reticulum (ER) stress in zoledronic acid (ZOL)-induced inflammation were analyzed in macrophages, and the regulatory mechanism of ER stress activation was next investigated. An in vitro model of BRONJ was established by treating RAW264.7 cells with ZOL. The activation of ER stress was analyzed by western blotting and transmission electron microscopy, and inflammation was assessed by quantitative real-time PCR and enzyme-linked immunosorbent assay. ER stress was significantly activated in ZOL-treated macrophages, and inhibition of ER stress by TUDCA, an ER stress inhibitor, suppressed ZOL-induced inflammation in macrophages. Mechanistically, phosphodiesterase 4B (PDE4B) was significantly increased in ZOL-treated macrophages. Forced expression of PDE4B promoted ER stress and inflammation, whereas PDE4B knockdown decreased ZOL-induced ER stress and inflammation in macrophages. More importantly, PDE4B inhibitor could improve ZOL-induced BRONJ in vivo. These data suggest that ZOL accelerates ER stress-mediated inflammation in BRONJ by increasing PDE4B expression. PDE4B inhibition may represent a potential therapeutic strategy for BRONJ. Subsequent research should concentrate on formulating medications that selectively target PDE4B, thereby mitigating the risk of BRONJ in patients undergoing bisphosphonate treatment.

Nanoengineering Calcium Peroxide‐Based Site‐Specific Delivery Platform to Efficiently Activate the cGAS‐STING Pathway for Cancer Immunotherapy by Amplified Endoplasmic Reticulum Stress

Abstract Currently, the understanding of the cyclic GMP‐AMP synthase (cGAS)‐stimulator of interferon genes (STING) pathway's involvement in efficient immunotherapy mainly revolves around the role of mitochondria or nucleus modulation. Nonetheless, the role of endoplasmic reticulum (ER) stress in activating the cGAS‐STING mechanism to boost immunity against tumors remains essentially unexplored. Herein, novel findings demonstrating that ER stress can be used as a strategy for stimulating the cGAS‐STING pathway, thereby augmenting the immune response against cancer, are presented. To accomplish this objective, ER‐targeting p‐methylbenzene sulfonamide‐tailored IR780 (p‐780) is synthesized and it is loaded into CaO2 nanoparticles, which are further functionalized with distearoyl phosphoethanolamine‐polyethylene glycol（DSPE‐PEG）‐biotin to form PEG/CaO2@p‐780 NPs. The disruption of calcium homeostasis, coupled with the heightened levels of reactive oxygen species (ROS) mediated by p‐780, along with hyperpyrexia, collectively contributes to the amplification of endoplasmic reticulum (ER) stress. This cascade of events effectively triggers the cGAS‐STING pathway and, in parallel, facilitates the degradation of the programmed cell death 1 ligand 1 (PD‐L1) protein. In addition, oxygen released through CaO2 decomposition is expected to promote p‐780–mediated phototherapy, while reversing the immunosuppressive tumor microenvironment associated with hypoxia. Furthermore, DSPE‐PEG‐biotin facilitates tumor site‐specific drug delivery through active targeting mediated by the biotin receptor. Collectively, PEG/CaO2@p‐780 nanoparticles successfully activate systemic antitumor immunity by enhancing ER stress.

CHIP suppresses the proliferation and migration of A549 cells by mediating the ubiquitination of eIF2α and upregulation of tumor suppressor RBM5

The PERK-eIF2α pathway plays an essential role in endoplasmic reticulum (ER) stress. When the PERK-eIF2α pathway is activated, PERK phosphorylates eIF2α (p-eIF2α) at Ser51 and quenches global protein synthesis. In this study, we verified eIF2α as a bona fide substrate of the E3 ubiquitin ligase CHIP both in vitro and in cells. CHIP mediated the ubiquitination and degradation of nonphosphorylated eIF2α in a chaperone-independent manner and promoted the upregulation of the transcription factor ATF4 under ER stress conditions. ATF4 induced the transcriptional enhancement of the tumor suppressor genes PTEN and RBM5. Although transcription was enhanced, the PTEN protein was subsequently degraded by CHIP, but the expression of the RBM5 protein was upregulated, thereby suppressing the proliferation and migration of A549 cells. Overall, our study established a new mechanism that deepened the understanding of the PERK-eIF2α pathway through the ubiquitination and degradation of eIF2α. The crosstalk between the phosphorylation and ubiquitination of eIF2α shed light on a new perspective for tumor progression.

Responses and correlation among ER stress, Ca2+ homeostasis, and fatty acid metabolism in Penaeus vannamei under ammonia stress

The role of endoplasmic reticulum (ER) stress, Ca2+ homeostasis, and fatty acid metabolism in the environmental adaptation of aquatic animals is significant, but further confirmation of the relationship between these factors is needed. This study aimed to investigate the responses and correlations among ER stress, Ca2+ homeostasis, and fatty acid metabolism in Penaeus vannamei under ammonia stress. A total of 640 P. vannamei weighing 3.0 ± 0.4 g were selected and exposed to different total ammonia concentrations (0 mg/L for the control group and 3.80, 7.60, and 11.40 mg/L for the stress groups). The experiment involved a 96 h ammonia stress period to assess indicators related to ER stress, Ca2+ homeostasis, and fatty acid metabolism. The experimental results revealed that after 12 h, exposure to ammonia induced the ER stress response in the hepatopancreas of the shrimp. The groups exposed to concentrations of 3.8 mg/L and 7.6 mg/L exhibited an increase in ER Ca2+ efflux, a decrease in influx, an elevation in mitochondrial Ca2+ influx, an enhanced energy demand within the organism, and substantial consumption of triglycerides. The 11.3 mg/L group exhibited a significant enhancement in fatty acid metabolism. At 24 h, the ER stress response induced by ammonia in the shrimp exhibited a gradual recovery. In the 7.6 mg/L and 11.3 mg/L groups, the ER Ca2+ influx and efflux exhibited significant enhancements, while the mitochondrial Ca2+ influx decreased and the organism's energy demand increased. Moreover, there was a substantial enhancement in fatty acid metabolism. At 48 h, the ER stress response disappeared in each stress group, ER Ca2+ efflux was reduced, triglycerides were consumed, and the body's energy homeostasis was basically restored. At 96 h, a stress response reoccurred in the ER in each stress group, resulting in increased influx of Ca2+ into the ER, augmented energy demand within the organism, and notable enhancement in fatty acid metabolism. Pearson correlation analysis revealed a significant positive correlation between the NH3-N content in the hepatopancreas and the expression of ER stress-related genes, as well as between ER Ca2+ influx/efflux and energy homeostasis/fatty acid metabolism. The findings indicate that the stress induced by ammonia triggers an ER stress response in P. vannamei, resulting in ER Ca2+ efflux and mitochondrial Ca2+ influx, which, in turn, enhances fatty acid metabolism to generate additional energy for adaptation in stressful environments. This study contributes to a deeper understanding of the environmental adaptability of P. vannamei in the context of Ca2+ homeostasis.

Alcohol induces ER stress and apoptosis by inducing oxidative stress and disruption of calcium homeostasis in glial cells

Alcohol has teratogenic effects that can cause developmental abnormalities and alter anatomical and functional characteristics of the developed brain and other organs. Glial cells play a crucial role in alcohol metabolism and protect neurons from toxic effects of alcohol. However, chronic alcohol exposure can lead to uncontrollable levels of reactive oxygen species, resulting in the death of glial cells and exposing neuronal cells to the toxic effects of alcohol. The exact molecular mechanism of alcohol-induced glial cell death has not been fully explored. This study reported that different concentrations of alcohol induce different expressions of ER stress markers in glial cells, focusing on the role of endoplasmic reticulum (ER) stress. Alcohol-induced concentration-dependent toxicity in both cells also induced oxidative stress, leading to mitochondrial damage. The expression of p53 and apoptotic proteins was significantly up-regulated after alcohol exposure, while Bcl2 (anti-apoptotic) was down-regulated. The signalling pathway for ER stress was activated and up-regulated marker proteins in a concentration-dependent manner. Cells pre-treated with BAPTA-AM and NAC showed significant resistance against alcohol assault compared to other cells. These in vitro findings will prove valuable for defining the mechanism by which alcohol modulates oxidative stress, mitochondrial and ER damage leading to glial cell death.

An investigation of the endoplasmic reticulum stress in obesity exposure in the prenatal period

ObjectivesExposure to maternal obesity has been shown to make offspring more prone to cognitive and metabolic disorders later in life. Although the underlying mechanisms are unclear, the role of endoplasmic reticulum (ER) stress in the fetal programming process is remarkable. ER stress can be activated by many chronic diseases, including obesity and diabetes. Therefore, our study aimed to investigate the role of ER stress caused by maternal diet-induced obesity in the offspring hippocampus. We also evaluated the protective effect of N-acetylcysteine (NAC) against ER stress. MethodsA rat obesity model was created by providing a high-fat (60 % kcal) diet. N-acetylcysteine (NAC) was administered at a dosage of 150 mg/kg via the intragastric route. The animals were mated at the age of 12 weeks. The same diet was maintained during pregnancy and lactation. The experiment was terminated on the postnatal 28th day, and the offspring's brain tissues were examined. Immunohistochemical staining for ER stress markers was performed on sections taken from tissues after routine histological procedures. ResultsThe results revealed increased GRP78, PERK, and eIF2α immunoreactivities in the hippocampal dentate gyrus (DG) and cornu ammonis 1 (CA1) regions in the obese group offspring, while the expression of those markers in those regions normalized with NAC supplementation (p < 0.01). Statistical analysis of XBP1 immunoreactivity H-scores revealed no difference between the study groups (p > 0.05). DiscussionThese results suggest that exposure to obesity during the prenatal period may cause increased ER stress in hippocampal neurons, which have an important role in the regulation of learning, memory and behavior, and this may contribute to decreased cognitive performance. On the other hand, NAC stands out as an effective agent that can counteract hippocampal ER stress.

Abstract 3247: Combination therapy using PERK and PD1/PD-L1 inhibitors reprograms tumor associated macrophages and reduces tumor burden

Abstract Background: The role of endoplasmic reticulum (ER) stress is profound in increasing malignant activity of neoplastic tumor cells and has been recently demonstrated to also increase immunosuppressive activity of tumor-associated macrophages (TAMs). Immunosuppressive TAM activity is thought to underly resistance to PD-1/PD-L1-targeted immune checkpoint inhibitors used for cancer therapy. Protein kinase RNA-like endoplasmic reticulum kinase (PERK) is a rate-limiting enzyme central to the ER-stress response mechanism that transduces ER-stress signals in cells to regulate protein synthesis, cell death, and cell survival. We hypothesized that inhibition of PERK would improve responses to ICI therapy by reprogramming TAM from immunosuppressive to immunoactivating cells. Methods: To investigate if ER-stress underlies resistance to PD-1/PD-L1 targeted therapies, we utilized ex vivo assays to investigate ER-stress regulation of macrophage phenotype, and in vivo syngeneic murine models of melanoma growth, with HC-5404 (PERKi), a selective and potent first-in-human small molecule PERK inhibitor currently in a phase 1 clinical trial for solid tumors (NCT04834778). Results: Treatment with PERKi sensitized αPD-1/PD-L1 mAb-resistant melanoma tumors (Y1.7/YR1.7) to PD-1/PD-L1 blockade with concomitant increase in tumor infiltrating leukocytes, TH1- reprogrammed TAM, and cytotoxic CD8+ T cells. In addition to tumor microenvironment changes by PERKi, gene expression analysis confirmed reprograming of the tumor microenvironment, marked by a relative increase in TH1-associated genes and downregulation of TH2-associated genes when compared with untreated tumors. We utilized an ex vivo macrophage-splenocyte co-culture assay to depict macrophage dependent T cell suppression prevalent in tumors. This revealed that treating macrophages with PERKi prior to co-culturing with T cells or adding PERKi to the macrophage-T cell co-culture relieved macrophage dependent T cell suppression, illustrating a potential mechanism of therapeutic efficacy. We are now studying how ER-stress is regulated in TAMs and are focusing on identifying components of PERK-dependent cell signaling that increases the tumor promoting behavior of TAMs. Conclusions: The combination therapy targeting PERK and PD-1/PD-L1 signaling increased adaptive immune responses, reprogramed TAMs and reduced tumor growth kinetics. Results from these studies highlight a role for ER-stress signaling in TAMs to maintain an immunosuppressive tumor microenvironment and demonstrate the potential therapeutic strategy of PERK inhibition in αPD-1/PD-L1 resistant tumors. Citation Format: Sushil Kumar, Michael McCane, Jeremy Drees, Nandita Bose, Lisa Coussens. Combination therapy using PERK and PD1/PD-L1 inhibitors reprograms tumor associated macrophages and reduces tumor burden [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3247.

Long non-coding RNAs TUG1 and MEG3 in patients with type 2 diabetes and their association with endoplasmic reticulum stress markers.

Long non-coding RNAs (lncRNAs), including taurine upregulated gene 1 (TUG1), metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), and maternally expressed 3 (MEG3) play a regulatory role in endoplasmic reticulum (ER) stress. The present study aimed to investigate the expression of these lncRNAs in patients with type 2 diabetes and their association with biochemical and ER stress parameters. Participants included 57 patients with diabetes and 32 healthy individuals. Real-time PCR was performed to assess MALAT1, TUG1, MEG3, ATF4, and CHOP gene expression in peripheral blood mononuclear cells. Plasma GRP78, advanced glycation end products (AGEs), and insulin were measured using enzyme-linked immunosorbent assay (ELISA), and insulin resistance (IR) was calculated by the homeostasis model assessment of insulin resistance (HOMA-IR). The expression of TUG1, MEG3, ATF4, and CHOP genes was significantly increased in the patients with diabetes compared to healthy individuals. MALAT1 gene expression was also higher in patients group; although it did not reach significant levels. TUG1 and MEG3 expression revealed significant positive correlations with the indices of glycemic control, including FBS, HbA1c, HOMA-IR, and AGEs, as well as markers of ER stress. MALAT1 expression was also positively correlated with ATF4 and AGEs. The expression levels of TUG1 and MEG3 lncRNAs were increased in patients with diabetes and were associated with glycemic control and components of ER stress. Thus, these lncRNAs might be considered appropriate markers to identify ER stress due to hyperglycemia.

Abstract B060: Investigating the role of ERphagy in pancreatic cancer

Abstract Pancreatic ductal adenocarcinoma (PDAC) harbors mutations in KRAS in greater than 90% of cases and is characterized by a dense, fibrotic stroma that fosters the formation of a hypoxic, nutrient-poor tumor microenvironment. Tumor cells counteract these stresses through the hyperactivation of multiple nutrient scavenging pathways, including macropinoytosis and macroautophagy. Whereas the role of the latter in the regulation of PDAC growth has been extensively studied, much less is known about the role of endoplasmic reticulum (ER)-specific autophagy (ERphagy), a homeostatic mechanism involving ER membrane remodeling which promotes the clearance of misfolded protein aggregates, thereby supporting proteostasis. Using an ERphagy reporter system, we found that pancreatic cancer cells display mutant KRas-dependent suppression of ERphagy both at baseline and in the context of nutrient deprivation, which was partially dependent on the ER-resident receptor CCPG1. Furthermore, direct perturbation of the 26S proteasome with bortezomib enhanced ERphagy, suggesting that the attenuated ERphagy capacity in pancreatic cancer cells may reflect a greater dependence on proteasomal activity for the maintenance of proteostasis. Significantly, the knockdown of CCPG1 but not other ERphagy receptors augmented the growth-suppressive effects of bortezomib in vitro, an effect likely caused by unresolved proteotoxic stress. Overall, our findings implicate CCPG1-mediated ERphagy in pancreatic cancer cell survival and identify a targetable cell-intrinsic vulnerability that can potentiate the cytotoxic effects of bortezomib, which alone is clinically ineffective in treating PDAC. Citation Format: Sandra L. Vogt, Dafna Bar-Sagi. Investigating the role of ERphagy in pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr B060.

Retraction: Protein Tyrosine Phosphatase 1B and Insulin Resistance: Role of Endoplasmic Reticulum Stress/Reactive Oxygen Species/Nuclear Factor Kappa B Axis.

Retraction: Protein Tyrosine Phosphatase 1B and Insulin Resistance: Role of Endoplasmic Reticulum Stress/Reactive Oxygen Species/Nuclear Factor Kappa B Axis.

Endoplasmic reticulum stress contributes to cisplatin-induced chronic kidney disease via the PERK-PKCδ pathway.

Cisplatin is an effective chemotherapeutic drug, but it may induce both acute and chronic kidney problems. The pathogenesis of chronic kidney disease (CKD) associated with cisplatin chemotherapy remains largely unclear. Mice and renal tubular cells were subjected to repeated low-dose cisplatin (RLDC) treatment to induce CKD and related pathological changes. The roles of endoplasmic reticulum (ER) stress, PERK, and protein kinase C-δ (PKCδ) were determined using pharmacological inhibitors and genetic manipulation. ER stress was induced by RLDC in kidney tubular cells in both in vivo and in vitro models. ER stress inhibitors given immediately after RLDC attenuated kidney dysfunction, tubular atrophy, kidney fibrosis, and inflammation in mice. In cultured renal proximal tubular cells, inhibitors of ER stress or its signaling kinase PERK also suppressed RLDC-induced fibrotic changes and the expression of inflammatory cytokines. Interestingly, RLDC-induced PKCδ activation, which was blocked by ER stress or PERK inhibitors, suggesting PKCδ may act downstream of PERK. Indeed, suppression of PKCδ with a kinase-dead PKCδ (PKCδ-KD) or Pkcδ-shRNA attenuated RLDC-induced fibrotic and inflammatory changes. Moreover, the expression of active PKCδ-catalytic fragment (PKCδ-CF) diminished the beneficial effects of PERK inhibitor in RLDC-treated cells. Co-immunoprecipitation assay further suggested PERK binding to PKCδ. These results indicate that ER stress contributes to chronic kidney pathologies following cisplatin chemotherapy via the PERK-PKCδ pathway.

A Novel Defined Endoplasmic Reticulum Stress-Related lncRNA Signature for Prognosis Prediction and Immune Therapy in Glioma.

Gliomas are a group of the most aggressive primary central nervous system tumors with limited treatment options. The abnormal expression of long non-coding RNA (lncRNA) is related to the prognosis of glioma. However, the role of endoplasmic reticulum (ER) stress-associated lncRNAs in glioma prognosis has not been reported. In this paper, we obtained ER stress-related lncRNAs by co-expression analysis, and then a risk signature composed of 6 ER stress-related lncRNAs was constructed using Cox regression analysis. Glioma samples in The Cancer Genome Atlas (TCGA) were separated into high- and low-risk groups based on the median risk score. Compared with the low-risk group, patients in the high-risk group had shorter survival times. Additionally, we verified the predictive ability of these candidate lncRNAs in the testing set. Three glioma patient subgroups (cluster 1/2/3) were identified by consensus clustering. We further analysed the abundance of immune-infiltrating cells and the expression levels of immune checkpoint molecules in both three subgroups and two risk groups, respectively. Immunotherapy and anticancer drug response prediction showed that ER stress-related lncRNA risk signature positively correlates with responding to immune checkpoints and chemosensitivity. Functional analysis showed that these gene sets are enriched in the malignant process of tumors. Finally, LINC00519 was chosen for functional experiments. The silence of LINC00519 restrained the migration and invasion of glioma cells. Hence, those results indicated that ER stress-related lncRNA risk signature could be a potential treatment target and a prognosis biomarker for glioma patients.

Dezocine induces apoptosis in human cervical carcinoma Hela cells via the endoplasmic reticulum stress pathway.

Dezocine, a dual agonist and antagonist of the μ-opioid receptor and κ-opioid receptor, is widely used as an analgesic in China. At present, there are few studies on anti-tumor effects of dezocine, most of which are used to treat cancer pain. However, it has recently been reported that dezocine can induce apoptosis of triple negative breast cancer cells. Dezocine may have some anti-tumor activity, but the effect and potential mechanism of dezocine in the treatment of other types of cancer remain to be fully studied. The purpose of the present study was to investigate the effect of dezocine on human Hela cervical carcinoma cells, and to elucidate the underlying molecular mechanisms. We performed CCK-8 assays, clone formation assays, xenograft, flow cytometry analysis, western blot and RNA-seq analysis to evaluate the effects of dezocine on Hela cells. In addition, the role of endoplasmic reticulum (ER) stress in dezocine-induced apoptosis was investigated using qPCR and western blot analysis. Dezocine inhibited Hela cell viability in dose-dependent and time-dependent manners, and notably did not achieve this effect by targeting the opioid receptors. Further mechanistic studies demonstrated that dezocine activated ER stress by upregulating the expression of GRP78, IRE1 and p-JNK, and that dezocine-induced apoptosis was attenuated when the ER stress pathway was blocked. Our results provide a foundation to support the redefinition of dezocine as a novel, adjuvant treatment for patients with cervical cancer, although further research will be required to support its application in clinical practice.

Endoplasmic reticulum stress and mitochondrial injury are critical molecular drivers of AlCl3-induced testicular and epididymal distortion and dysfunction: protective role of taurine

Aluminum, the third most plentiful metal in the Earth’s crust, has potential for human exposure and harm. Oxidative stress plays an essential role in producing male infertility by inducing defects in sperm functions. We aimed to investigate the role of endoplasmic reticulum (ER) stress and mitochondrial injury in the pathogenesis of aluminum chloride (AlCl3)-induced testicular and epididymal damage at the histological, biochemical, and molecular levels, and to assess the potential protective role of taurine. Forty-eight adult male albino rats were separated into four groups (12 in each): negative control, positive control, AlCl3, and AlCl3 plus taurine groups. Testes and epididymis were dissected. Histological and immunohistochemical (Bax and vimentin) studies were carried out. Gene expression of vimentin, PCNA, CHOP, Bcl-2, Bax, and XBP1 were investigated via quantitative real-time polymerase chain reaction (qRT-PCR), besides estimation of malondialdehyde (MDA) and total antioxidant capacity (TAC). Light and electron microscopic examinations of the testes and epididymis revealed pathological changes emphasizing both mitochondrial injury and ER stress in the AlCl3 group. Taurine-treated rats showed a noticeable improvement in the testicular and epididymal ultrastructure. Moreover, they exhibited increased gene expression of vimentin, Bcl-2, and PNCA accompanied by decreased CHOP, Bax, and XBP1 gene expression. In conclusion, male reproductive impairment is a significant hazard associated with AlCl3 exposure. Both ER stress and mitochondrial impairment are critical mechanisms of the deterioration in the testes and epididymis induced by AlCl3, but taurine can amend this.

The Role of Endoplasmic Reticulum and Mitochondria in Maintaining Redox Status and Glycolytic Metabolism in Pluripotent Stem Cells.

Pluripotent stem cells (PSCs), including embryonic stem cells and induced pluripotent stem cells (iPSCs), can be applicable for regenerative medicine. They strangely rely on glycolysis metabolism akin to aerobic glycolysis in cancer cells. Upon differentiation, PSCs undergo a metabolic shift from glycolysis to oxidative phosphorylation (OXPHOS). The metabolic shift depends on organelles maturation, transcriptome modification, and metabolic switching. Besides, metabolism-driven chromatin regulation is necessary for cell survival, self-renewal, proliferation, senescence, and differentiation. In this respect, mitochondria may serve as key organelle to adapt environmental changes with metabolic intermediates which are necessary for maintaining PSCs identity. The endoplasmic reticulum (ER) is another organelle whose role in cellular identity remains under-explored. The purpose of our article is to highlight the recent progress on these two organelles' role in maintaining PSCs redox status focusing on metabolism. Topics include redox status, metabolism regulation, mitochondrial dynamics, and ER stress in PSCs. They relate to the maintenance of stem cell properties and subsequent differentiation of stem cells into specific cell types.

A comprehensive insight into autophagy and its potential signaling pathways as a therapeutic target in podocyte injury.

As part of the glomerular filtration membrane, podocyte is terminally differentiated, structurally unique, and highly specialized in maintaining kidney function. Proteinuria caused by podocyte injury (foot process effacement) is the clinical symptom of various kidney diseases (CKD), including nephrotic syndrome. Podocyte autophagy has become a powerful therapeutic strategy target in ameliorating podocyte injury. Autophagy is known to be associated significantly with sirtuin-1, proteinuria, and podocyte injury. Various key findings in podocyte autophagy were reported in the past ten years, such as the role of endoplasmic reticulum (ER) stress in podocyte autophagy impairment, podocyte autophagy-related gene, essential roles of the signaling pathways: Mammalian Target of Rapamycin (mTOR)/ Phosphoinositide 3-kinase (PI3k)/ serine/threonine kinase 1 (Akt) in podocyte autophagy. These significant factors caused podocyte injury associated with autophagy impairment. Sirtuin-1 was reported to have a vital key role in mTOR signaling, 5'AMP-activated protein kinase (AMPK) regulation, autophagy activation, and various critical pathways associated with podocyte's function and health; it has potential value to podocyte injury pathogenesis investigation. From these findings, podocyte autophagy has become an attractive therapeutic strategy to ameliorate podocyte injury, and this review will provide an in-depth review on therapeutic targets he podocyte autophagy.

Endoplasmic reticulum stress promotes local immunoglobulin E production in allergic rhinitis.

BackgroundThe role of endoplasmic reticulum (ER) stress in the pathogenesis of allergic rhinitis (AR) remains elusive.MethodsReal‐time polymerase chain reaction (RT‐PCR), immunohistochemistry, and western blotting analyses were performed to detect the expression of ER stress and unfolded protein response markers: 78‐kDa glucose‐regulated protein (GRP78), C/EBP homologous protein (CHOP), activating transcription factor 6 (ATF6α), spliced X‐box binding protein 1 (sXBP‐1), and phosphorylated eukaryotic initiation factor 2α (p‐eIF2α), in inferior turbinate tissue samples from patients with AR and non‐AR controls. Nasal tissues from patients with AR were cultured ex vivo and treated with 4‐phenylbutyric acid (4‐PBA), an ER stress inhibitor.ResultsCompared to those in non‐AR controls, the mRNA and protein levels of GRP78, CHOP, ATF6α, sXBP‐1, and p‐eIF2α were significantly increased in nasal tissues from patients with AR. GRP78 and CHOP were mainly expressed in CD138+ plasma cells in nasal tissues from patients with AR. The frequency of IgE+CD138+ plasma cells was significantly higher in nasal tissues from patients with AR than that in non‐AR controls. IgE levels in nasal secretions and tissues were positively correlated with GRP78 and CHOP mRNA levels in the nasal tissues. After 4‐PBA treatment, the protein expression of GRP78, CHOP, ATF6α, sXBP‐1, and p‐eIF2α was significantly reduced in cultured AR‐derived nasal tissues, and IgE levels were simultaneously decreased in cultured supernatants.ConclusionsER stress may be involved in the regulation of local IgE production in patients with AR. Inhibition of ER stress potentially provides a therapeutic avenue in AR by reducing local IgE production.Level of EvidenceNA

The Role of Endoplasmic Reticulum in the Differential Endurance against Redox Stress in Cortical and Spinal Astrocytes from the Newborn SOD1G93A Mouse Model of Amyotrophic Lateral Sclerosis.

Recent studies reported that the uptake of [18F]-fluorodeoxyglucose (FDG) is increased in the spinal cord (SC) and decreased in the motor cortex (MC) of patients with ALS, suggesting that the disease might differently affect the two nervous districts with different time sequence or with different mechanisms. Here we show that MC and SC astrocytes harvested from newborn B6SJL-Tg (SOD1G93A) 1Gur mice could play different roles in the pathogenesis of the disease. Spectrophotometric and cytofluorimetric analyses showed an increase in redox stress, a decrease in antioxidant capacity and a relative mitochondria respiratory uncoupling in MC SOD1G93A astrocytes. By contrast, SC mutated cells showed a higher endurance against oxidative damage, through the increase in antioxidant defense, and a preserved respiratory function. FDG uptake reproduced the metabolic response observed in ALS patients: SOD1G93A mutation caused a selective enhancement in tracer retention only in mutated SC astrocytes, matching the activity of the reticular pentose phosphate pathway and, thus, of hexose-6P dehydrogenase. Finally, both MC and SC mutated astrocytes were characterized by an impressive ultrastructural enlargement of the endoplasmic reticulum (ER) and impairment in ER–mitochondria networking, more evident in mutated MC than in SC cells. Thus, SOD1G93A mutation differently impaired MC and SC astrocyte biology in a very early stage of life.

Canopy Homolog 2 as a Novel Molecular Target in Hepatocarcinogenesis.

Simple SummaryProtein canopy homolog 2 (CNPY2) controls the outgrowth of neurites through positive regulation of their outgrowth in neuroblastoma and pheochromocytoma due to stabilizing the myosin regulatory light chain (MRLC). Given the important role in endoplasmic reticulum (ER) stress and proteolysis, we focused on investigation of CNPY2 expression in mouse and human hepatocarcinogenesis and its clinical relevance in virus-associated liver cancer. CNPY2 elevation and coordinated accumulation of numerous cytoskeletal proteins and those involved in ER and mitochondrial stresses was found in mouse altered foci and tumors by proteome analysis of microdissected lesions. In Huh7 and HepG2 human liver cancer cells, CNPY2 increase was significantly associated with cell cycle progression, activated cell proliferation and invasion. CNPY2 expression was high in HCV-associated HCC patients, being positively associated with survival. To the best of our knowledge, this is the first report to demonstrate that CNPY2 may become a useful prognostic biomarker in HCV-associated HCC. In the present study, the role of a novel protein involved in neurite development and endoplasmic reticulum (ER) stress, canopy homolog 2 (CNPY2), was investigated in mouse and human hepatocarcinogenesis. Firstly, a sensitive quantitative and qualitative detection of protein expression using QSTAR Elite LC-Ms/Ms was performed for the analysis of lysates of microdissected hepatocellular altered foci (AF), adenomas (HCAs), carcinomas (HCCs) and peri-tumoral livers from C57Bl/6J mice treated with diethylnitrosamine (DEN) and then maintained for 27 or 38 weeks on basal diet. Significant overexpression of 18.5 kDa CNPY2 processed form was demonstrated in AF, HCAs and HCCs, while low expression was observed in the livers of DEN-treated and control mice. Furthermore, CNPY2 elevation in AF and tumors was coordinated with accumulation of numerous cytoskeletal proteins, including cytokeratins 8 and 18, actin, non-muscle myosin and septin 9 and those involved in ER and mitochondrial stresses such as calreticulin, prohibitins 1 and 2 and YME1-like-1. Knockdown of CNPY2 in Huh7 and HepG2 human liver cancer cells resulted in significant suppression of cell survival and invasive potential, inhibition of cyclin D1, induction of p21Waf1/Cip1 and suppression of the apoptosis inhibitor Bcl2. In contrast, transfection of a mouse CNPY2 (mCNPY2-Ds-Red) vector plasmid in Huh7 and HepG2 cancer cells, with subsequent accumulation of CNPY2 in the ER, resulted in significant increase in cancer cells survival. Clinicopathological analysis in 90 HCV-positive HCC patients, revealed significant association of CNPY2 overexpression with poor overall (p = 0.041) survival. Furthermore, CNPY2 increase was associated with vessel invasion (p = 0.038), poor histological differentiation (p = 0.035) and advanced clinical stage (p = 0.016). In conclusion, CNPY2 is a promising molecular target elevated early in hepatocarcinogenesis and prognostic marker for human HCV-associated HCC. CNPY2 is involved in the processes of ER stress, cell cycle progression, proliferation, survival and invasion of liver tumor cells.