Antitumor T cell function requires CPEB4-mediated adaptation to chronic endoplasmic reticulum stress
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ABSTRACT:
SUBMITTER: Mr. Marcos Fernandez-Alfara
PROVIDER: S-SCDT-10_15252-EMBJ_2022111494 | biostudies-other |
REPOSITORIES: biostudies-other
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Project description:The endoplasmic reticulum (ER) is an energy-sensing organelle with intimate ties to programming cell activation and metabolic fate. T-cell receptor (TCR) activation represents a form of acute cell stress and induces mobilization of ER Ca2+ stores. The role of the ER in programming T-cell activation and metabolic fate remains largely undefined. Gp96 is an ER protein with functions as a molecular chaperone and Ca2+ buffering protein. We hypothesized that the ER stress response may be important for CD4+ T-cell activation and that gp96 may be integral to this process. To test our hypothesis, we utilized genetic deletion of the gp96 gene Hsp90b1 in a CD4+ T cell-specific manner. We show that gp96-deficient CD4+ T cells cannot undergo activation-induced glycolysis due to defective Ca2+ mobilization upon TCR engagement. We found that activating naïve CD4+ T cells while inhibiting ER Ca2+ exchange, through pharmacological blockade of the ER Ca2+ channel inositol trisphosphate receptor (IP3R), led to a reduction in cytosolic Ca2+ content and generated a pool of CD62Lhigh/CD44low CD4+ T cells compared with wild-type (WT) matched controls. In vivo IP3R-inhibited CD4+ T cells exhibited elevated tumor control above WT T cells. Together, these data show that ER-modulated cytosolic Ca2+ plays a role in defining CD4+ T-cell phenotype and function. Factors associated with the ER stress response are suitable targets for T cell-based immunotherapies. Cancer Immunol Res; 5(8); 666-75. ©2017 AACR.
| S-EPMC5585019 | biostudies-literature
Project description:The large secretory glycoprotein thyroglobulin is the primary translation product of thyroid follicular cells. This difficult-to-fold protein is susceptible to structural alterations that disable export of the misfolded thyroglobulin from the endoplasmic reticulum (ER), which is a known cause of congenital hypothyroidism characterized by severe chronic thyrocyte ER stress. Nevertheless, individuals with this disease commonly grow a goiter, indicating thyroid cell survival and adaptation. To model these processes, here we continuously exposed rat PCCL3 thyrocytes to tunicamycin, which causes a significant degree of ER stress that is specifically attributable to thyroglobulin misfolding. We found that, in response, PCCL3 cells down-regulate expression of the "tunicamycin transporter" (major facilitator superfamily domain containing-2A, Mfsd2a). Following CRISPR/Cas9-mediated Mfsd2a deletion, PCCL3 cells could no longer escape the chronic effects of high-dose tunicamycin, as demonstrated by persistent accumulation of unglycosylated thyroglobulin; nevertheless, these thyrocytes survived and grew. A proteomic analysis of these cells adapted to chronic ER protein misfolding revealed many hundreds of up-regulated proteins, indicating stimulation of ER chaperones, oxidoreductases, stress responses, and lipid biosynthesis pathways. Further, we noted increased phospho-AMP-kinase, suggesting up-regulated AMP-kinase activity, and decreased phospho-S6-kinase and protein translation, suggesting decreased mTOR activity. These changes are consistent with conserved cell survival/adaptation pathways. We also observed a less-differentiated thyrocyte phenotype with decreased PAX8, FOXE1, and TPO protein levels, along with decreased thyroglobulin mRNA levels. In summary, we have developed a model of thyrocyte survival and growth during chronic continuous ER stress that recapitulates features of congenital hypothyroid goiter caused by mutant thyroglobulin.
| S-EPMC7242714 | biostudies-literature
Project description:The large secretory glycoprotein, thyroglobulin, is the primary translation product of thyroid follicular cells. This difficult-to-fold protein is readily susceptible to structural alterations that render the misfolded thyroglobulin unable to be exported from the endoplasmic reticulum (ER) a known cause of congenital hypothyroidism, with severe, chronic thyrocyte ER stress. Nevertheless, patients with this disease commonly grow a goiter indicative of thyroid cell survival and adaptation. To model this, we have treated PCCl3 thyrocytes with continuous exposure to tunicamcyin (causing an ER stress that can be specifically attributed to thyroglobulin misfolding). In response, PCCl3 cells escape by downregulating expression of Mfsd2a (the tunicamycin transporter). By contrast, following CRISPR/Cas9-mediated deletion of Mfsd2a, PCCl3 cells cannot escape the continuous, chronic effects of high-dose tunicamycin (as demonstrated by persistent accumulation of unglycosylated thyroglobulin); nevertheless the thyrocytes live and grow. A comprehensive proteomic analysis of these cells adapted to chronic ER protein misfolding reveals many hundreds of up-regulated proteins, supporting stimulation of ER chaperones, oxidoreductases, and stress responses as well as lipid biosynthesis pathways. Further, we noted: a) increased phospho-AMP-kinase-B (suggesting upregulated AMPK activity) and decreased phospho-S6 and protein translation (suggesting decreased mTOR activity), consistent with conserved cell survival/adaptation pathways; and b) a suggestion of less differentiated thyrocyte phenotype with decreased PAX8, FOXE1, and TPO protein, as well as a significant decrease of thyroglobulin mRNA levels.
2020-02-25 | MSV000085006 | MassIVE
Project description:The new type 2 diabetes drug, dapagliflozin, reduces blood glucose levels and body weight by inhibiting sodium glucose transporter 2 (SGLT2) in proximal tubular cells. SGLT2 inhibitors might modulate glucose influx into renal tubular cells, thereby regulating the metabolic conditions that cause endoplasmic reticulum (ER) stress in the cells. In this study, we examined the effect of dapagliflozin on ER stress in the HK-2 proximal tubular cell line and in the kidney of db/db mice to characterise its function in diabetic nephropathy (DN). We found that dapagliflozin regulated ER stress-mediated apoptosis in vitro and in vivo. Only the elf2?-ATF4-CHOP pathway was regulated under these conditions. Notably, the drug rescued C2 ceramide-induced ER stress-mediated apoptosis and ER stress-mediated apoptosis, which might occur in DN, in db/db mice. Our study shows a novel role for dapagliflozin as an inhibitor of ER stress and suggests that dapagliflozin might be useful for the prevention of DN.
| S-EPMC6614429 | biostudies-literature
Project description:Endoplasmic reticulum (ER) stress leads to endothelial dysfunction which is commonly associated in the pathogenesis of several cardiovascular diseases. We explored the vascular protective effects of chronic treatment with paeonol (2'-hydroxy-4'-methoxyacetophenone), the major compound from the root bark of Paeonia suffruticosa on ER stress-induced endothelial dysfunction in mice. Male C57BL/6J mice were injected intraperitoneally with ER stress inducer, tunicamycin (1 mg/kg/week) for 2 weeks to induce ER stress. The animals were co-administered with or without paeonol (20 mg/kg/oral gavage), reactive oxygen species (ROS) scavenger, tempol (20 mg/kg/day) or ER stress inhibitor, tauroursodeoxycholic acid (TUDCA, 150 mg/kg/day) respectively. Blood pressure and body weight were monitored weekly and at the end of treatment, the aorta was isolated for isometric force measurement. Protein associated with ER stress (GRP78, ATF6 and p-eIF2?) and oxidative stress (NOX2 and nitrotyrosine) were evaluated using Western blotting. Nitric oxide (NO) bioavailability were determined using total nitrate/nitrite assay and western blotting (phosphorylation of eNOS protein). ROS production was assessed by en face dihydroethidium staining and lucigenin-enhanced chemiluminescence assay, respectively. Our results revealed that mice treated with tunicamycin showed an increased blood pressure, reduction in body weight and impairment of endothelium-dependent relaxations (EDRs) of aorta, which were ameliorated by co-treatment with either paeonol, TUDCA and tempol. Furthermore, paeonol reduced the ROS level in the mouse aorta and improved NO bioavailability in tunicamycin treated mice. These beneficial effects of paeonol observed were comparable to those produced by TUDCA and tempol, suggesting that the actions of paeonol may involve inhibition of ER stress-mediated oxidative stress pathway. Taken together, the present results suggest that chronic treatment with paeonol preserved endothelial function and normalized blood pressure in mice induced by tunicamycin in vivo through the inhibition of ER stress-associated ROS.
| S-EPMC5451063 | biostudies-literature
Project description:Cells exposed to sustained endoplasmic reticulum (ER) stress undergo programmed cell death and display features typical of apoptosis, such as cysteine aspartyl protease (caspase) activation, cytochrome c release, and DNA fragmentation. Here, we show that the execution of cell death induced by ER stress is mediated via the proteasome. Inhibition of the proteasome by lactacystin prevented ER stress-induced degradation of Bcl-2, release of cytochrome c, processing of effector caspase-3, and exposure of phosphatidylserine. Owing to the ability of lactacystin to inhibit cytochrome c release, we propose that the pro-apoptotic activity of the proteasome lies upstream of mitochondrial activation. Thus, the proteasome serves as a principal mediator of ER stress-induced cell death in this system.
| S-EPMC2748804 | biostudies-literature
Project description:Soluble proteins are enriched in the endoplasmic reticulum (ER) by retrograde transport from the Golgi that is mediated by the KDEL receptors. In addition to the classic carboxyl-terminal KDEL motif, a variety of sequence variants are also capable of receptor binding that result in ER localization. Although different ER localization signals that exhibit varying affinities for the KDEL receptors exist, whether there are functional implications was unknown. The present study determines whether AGR2 requires a specific ER localization signal to be functionally active. AGR2 is expressed in most human adenocarcinomas and serves a role in promoting growth and the transformed phenotype. Using two different cell lines in which AGR2 induces expression of either the EGFR ligand amphiregulin or the transcription factor CDX2, only the highly conserved wild-type carboxyl-terminal KTEL motif results in the appropriate outcome. Deletion of the KTEL motif results in AGR2 secretion and loss of AGR2 function. AGR2 function is also lost when ER residence is achieved with a carboxyl-terminal KDEL or KSEL instead of a KTEL motif. Thus variations in ER localization sequences may serve a specific functional role, and in the case of AGR2, this role is served specifically by KTEL.
| S-EPMC3281655 | biostudies-literature
Project description:Falcarindiol (FAD) is a natural polyyne with various beneficial biological activities. We show here that FAD preferentially kills colon cancer cells but not normal colon epithelial cells. Furthermore, FAD inhibits tumor growth in a xenograft tumor model and exhibits strong synergistic killing of cancer cells with 5-fluorouracil, an approved cancer chemotherapeutic drug. We demonstrate that FAD-induced cell death is mediated by induction of endoplasmic reticulum (ER) stress and activation of the unfolded protein response (UPR). Decreasing the level of ER stress, either by overexpressing the ER chaperone protein glucose-regulated protein 78 (GRP78) or by knockout of components of the UPR pathway, reduces FAD-induced apoptosis. In contrast, increasing the level of ER stress by knocking down GRP78 potentiates FAD-induced apoptosis. Finally, FAD-induced ER stress and apoptosis is correlated with the accumulation of ubiquitinated proteins, suggesting that FAD functions at least in part by interfering with proteasome function, leading to the accumulation of unfolded protein and induction of ER stress. Consistent with this, inhibition of protein synthesis by cycloheximide significantly decreases the accumulation of ubiquitinated proteins and blocks FAD-induced ER stress and cell death. Taken together, our study shows that FAD is a potential new anticancer agent that exerts its activity through inducing ER stress and apoptosis.
| S-EPMC3434669 | biostudies-literature
Project description:RationaleTribbles (TRB)3 is an intracellular pseudokinase that modulates the activity of several signal transduction cascades. TRB3 has been reported to inhibit the activity of Akt protein kinases. TRB3 gene expression is highly regulated in many cell types, and amino acid starvation, hypoxia, or endoplasmic reticulum (ER) stress promotes TRB3 expression in noncardiac cells.ObjectiveThe objective of this work was to examine TRB3 expression and function in cultured cardiac myocytes and in mouse heart.Methods and resultsAgents that induced ER stress increased TRB3 expression in cultured cardiac myocytes while blocking insulin-stimulated Akt activation in these cells. Knockdown of TRB3 in cultured cardiac myocytes reversed the effects of ER stress on insulin signaling. Experimental myocardial infarction led to increased TRB3 expression in murine heart tissue in the infarct border zone suggesting that ER stress may play a role in pathological cardiac remodeling. Transgenic mice with cardiac-specific overexpression of TRB3 were generated and they exhibited normal contractile function but altered cardiac signal transduction and metabolism with reduced cardiac glucose oxidation rates. Transgenic TRB3 mice were also sensitized to infarct expansion and cardiac myocyte apoptosis in the infarct border zone after myocardial infarction.ConclusionsThese results demonstrate that TRB3 induction is a significant aspect of the ER stress response in cardiac myocytes and that TRB3 antagonizes cardiac glucose metabolism and cardiac myocyte survival.
| S-EPMC2913227 | biostudies-literature
Project description:Upregulation of SESTRIN 2 (SESN2) has been reported in response to diverse cellular stresses. In this study we demonstrate SESTRIN 2 induction following endoplasmic reticulum (ER) stress. ER stress-induced increases in SESTRIN 2 expression were dependent on both PERK and IRE1/XBP1 arms of the unfolded protein response (UPR). SESTRIN 2 induction, post ER stress, was responsible for mTORC1 inactivation and contributed to autophagy induction. Conversely, knockdown of SESTRIN 2 prolonged mTORC1 signaling, repressed autophagy and increased ER stress-induced cell death. Unexpectedly, the increase in ER stress-induced cell death was not linked to autophagy inhibition. Analysis of UPR pathways identified prolonged eIF2?, ATF4 and CHOP signaling in SESTRIN 2 knockdown cells following ER stress. SESTRIN 2 regulation enables UPR derived signals to indirectly control mTORC1 activity shutting down protein translation thus preventing further exacerbation of ER stress.
| S-EPMC4914282 | biostudies-literature