scholarly journals Senescent Cell Depletion Through Targeting BCL-Family Proteins and Mitochondria

2020 ◽  
Vol 11 ◽  
Author(s):  
Ying Fan ◽  
Jiaoqi Cheng ◽  
Huihong Zeng ◽  
Lijian Shao
Keyword(s):  
Adenine Nucleotide ◽  
The Body ◽  
Mitochondrial Dna Mutation ◽  
Dna Mutation ◽  
Unfolded Protein ◽  
Respiratory Complex I ◽  
Protein Response

Senescent cells with replicative arrest can be generated during genotoxic, oxidative, and oncogenic stress. Long-term retention of senescent cells in the body, which is attributed to highly expressed BCL-family proteins, chronically damages tissues mainly through a senescence-associated secretory phenotype (SASP). It has been documented that accumulation of senescent cells contributes to chronic diseases and aging-related diseases. Despite the fact that no unique marker is available to identify senescent cells, increased p16INK4a expression has long been used as an in vitro and in vivo marker of senescent cells. We reviewed five existing p16INK4a reporter mouse models to detect, isolate, and deplete senescent cells. Senescent cells express high levels of anti-apoptotic and pro-apoptotic genes compared to normal cells. Thus, disrupting the balance between anti-apoptotic and pro-apoptotic gene expression, such as ABT-263 and ABT-737, can activate the apoptotic signaling pathway and remove senescent cells. Mitochondrial abnormalities in senescent cells were also discussed, for example mitochondrial DNA mutation accumulation, dysfunctional mitophagy, and mitochondrial unfolded protein response (mtUPR). The mitochondrial-targeted tamoxifen, MitoTam, can efficiently remove senescent cells due to its inhibition of respiratory complex I and low expression of adenine nucleotide translocase-2 (ANT2) in senescent cells. Therefore, senescent cells can be removed by various strategies, which delays chronic and aging-related diseases and enhances lifespan and healthy conditions in the body.

scholarly journals Toxoplasma gondii co-opts the unfolded protein response to enhance migration and dissemination of infected host cells

2020 ◽  
Author(s):  
Leonardo Augusto ◽  
Jennifer Martynowicz ◽  
Parth H. Amin ◽  
Nada S. Alakhras ◽  
Mark H. Kaplan ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Host Cell ◽  
The Body ◽  
Host Cells ◽  
Migratory Activity ◽  
Unfolded Protein ◽  
The Unfolded Protein Response ◽  
Protein Response

AbstractToxoplasma gondii is an intracellular parasite that reconfigures its host cell to promote pathogenesis. One consequence of Toxoplasma parasitism is increased migratory activity of host cells, which facilitates dissemination. Here we show that Toxoplasma triggers the unfolded protein response (UPR) in host cells through calcium release from the endoplasmic reticulum (ER). We further found that host IRE1, an ER stress sensor protein activated during Toxoplasma infection, also plays a noncanonical role in actin remodeling by binding filamin A in infected cells. By inducing cytoskeletal remodeling via IRE1 oligomerization in host cells, Toxoplasma enhances host cell migration in vitro and dissemination of the parasite to host organs in vivo. Our study identifies novel mechanisms used by Toxoplasma to induce dissemination of infected cells, providing new insights into strategies for treatment of toxoplasmosis.ImportanceCells that are infected with the parasite Toxoplasma gondii exhibit heightened migratory activity, which facilitates dissemination of the infection throughout the body. In this study, we identify a new mechanism used by Toxoplasma to hijack its host cell and increase its mobility. We further show that the ability of Toxoplasma to increase host cell migration does not involve the enzymatic activity of IRE1, but rather IRE1 engagement with actin cytoskeletal remodeling. Depletion of IRE1 from infected host cells reduces their migration in vitro and significantly hinders dissemination of Toxoplasma in vivo. Our findings reveal a new mechanism underlying host-pathogen interactions, demonstrating how host cells are co-opted to spread a persistent infection around the body.

scholarly journals USP19 deubiquitinating enzyme inhibits muscle cell differentiation by suppressing unfolded-protein response signaling

2015 ◽  
Vol 26 (5) ◽  
pp. 913-923 ◽  
Author(s):  
Benjamin Wiles ◽  
Miao Miao ◽  
Erin Coyne ◽  
Louise Larose ◽  
Andrey V. Cybulsky ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
Unfolded Protein Response ◽  
Muscle Cell ◽  
Deubiquitinating Enzyme ◽  
Muscle Cell Differentiation ◽  
Unfolded Protein ◽  
The Unfolded Protein Response ◽  
Protein Response

USP19 deubiquitinating enzyme has two isoforms, cytoplasmic and endoplasmic reticulum (ER) localized. The ER-localized isoform specifically suppresses muscle cell differentiation in vitro and appears to do so by inhibiting the unfolded-protein response that occurs during such differentiation. In vivo, loss of USP19 promotes muscle regeneration following injury.

scholarly journals Pentoxifylline Attenuates Methionine- and Choline-Deficient-Diet-Induced Steatohepatitis by Suppressing TNF-αExpression and Endoplasmic Reticulum Stress

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Min Kyung Chae ◽  
Sang Gyu Park ◽  
Sun-Ok Song ◽  
Eun Seok Kang ◽  
Bong Soo Cha ◽  
...  
Keyword(s):  
Er Stress ◽  
Deficient Diet ◽  
Group Iii ◽  
Unfolded Protein ◽  
Sd Rats ◽  
Group I ◽  
Hep3b Cells ◽  
Protein Response

Background. Pentoxifylline (PTX) anti-TNF properties are known to exert hepatoprotective effects in various liver injury models. The aim of this study was to investigate whether PTX has beneficial roles in the development of methionine- and choline-deficient-(MCD-) diet-induced NAFLD SD ratsin vivoand TNF-α-induced Hep3B cellsin vitro.Methods. SD Rats were classified according to diet (chow or MCD diet) and treatment (normal saline or PTX injection) over a period of 4 weeks: group I (chow + saline,n=4), group II (chow + PTX), group III (MCD + saline), and group IV (MCD + PTX). Hep3B cells were treated with 100 ng/ml TNF-α(24 h) in the absence or presence of PTX (1 mM).Results. PTX attenuated MCD-diet-induced serum ALT levels and hepatic steatosis. In real-time PCR and western blotting analysis, PTX decreased MCD-diet-induced TNF-alpha mRNA expression and proapoptotic unfolded protein response by ER stress (GRP78, p-eIF2, ATF4, IRE1α, CHOP, and p-JNK activation)in vivo. PTX (1 mM) reduced TNF-α-induced activation of GRP78, p-eIF2, ATF4, IRE1α, and CHOPin vitro.Conclusion. PTX has beneficial roles in the development of MCD-diet-induced steatohepatitis through partial suppression of TNF-αand ER stress.

scholarly journals A Novel Transcription Factor, ERD15 (Early Responsive to Dehydration 15), Connects Endoplasmic Reticulum Stress with an Osmotic Stress-induced Cell Death Signal

2011 ◽  
Vol 286 (22) ◽  
pp. 20020-20030 ◽  
Author(s):  
Murilo S. Alves ◽  
Pedro A. B. Reis ◽  
Silvana P. Dadalto ◽  
Jerusa A. Q. A. Faria ◽  
Elizabeth P. B. Fontes ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Death ◽  
Transcription Factor ◽  
Osmotic Stress ◽  
Er Stress ◽  
Unfolded Protein ◽  
Eukaryotic Organisms ◽  
Protein Response

As in all other eukaryotic organisms, endoplasmic reticulum (ER) stress triggers the evolutionarily conserved unfolded protein response in soybean, but it also communicates with other adaptive signaling responses, such as osmotic stress-induced and ER stress-induced programmed cell death. These two signaling pathways converge at the level of gene transcription to activate an integrated cascade that is mediated by N-rich proteins (NRPs). Here, we describe a novel transcription factor, GmERD15 (Glycine max Early Responsive to Dehydration 15), which is induced by ER stress and osmotic stress to activate the expression of NRP genes. GmERD15 was isolated because of its capacity to stably associate with the NRP-B promoter in yeast. It specifically binds to a 187-bp fragment of the NRP-B promoter in vitro and activates the transcription of a reporter gene in yeast. Furthermore, GmERD15 was found in both the cytoplasm and the nucleus, and a ChIP assay revealed that it binds to the NRP-B promoter in vivo. Expression of GmERD15 in soybean protoplasts activated the NRP-B promoter and induced expression of the NRP-B gene. Collectively, these results support the interpretation that GmERD15 functions as an upstream component of stress-induced NRP-B-mediated signaling to connect stress in the ER to an osmotic stress-induced cell death signal.

scholarly journals Is Surface Metastability of Today’s Ceramic Bearings a Clinical Issue?

2021 ◽  
Vol 5 (10) ◽  
pp. 273
Author(s):  
Alessandro Alan Porporati ◽  
Laurent Gremillard ◽  
Jérôme Chevalier ◽  
Rocco Pitto ◽  
Marco Deluca
Keyword(s):  
Raman Spectroscopy ◽  
The Body ◽  
Clinical Issue ◽  
Surface Stability ◽  
In Vitro Aging ◽  
Aging Kinetics ◽  
Many Sources

Recent studies on zirconia-toughened alumina (ZTA) evidenced that in vivo aged implants display a much higher monoclinic zirconia content than expected from in vitro simulations by autoclaving. At the moment, there is no agreement on the source of this discrepancy: Some research groups ascribe it to the effect of mechanical impact shocks, which are generally not implemented in standard in vitro aging or hip walking simulators. Others invoke the effect of metal transfer, which should trigger an autocatalytic reaction in the body fluid environment, accelerating the kinetics of tetragonal-to-monoclinic transformation in vivo. Extrapolations of the aging kinetics from high (autoclave) to in vivo temperature are also often disputed. Last, Raman spectroscopy is by far the preferred method to quantify the amount of monoclinically transformed zirconia. There are, however, many sources of errors that may negatively affect Raman results, meaning that the final interpretation might be flawed. In this work, we applied Raman spectroscopy to determine the monoclinic content in as-received and in vitro aged ZTA hip joint implants, and in one long-term retrieval study. We calculated the monoclinic content with the most used equations in the literature and compared it with the results of X-ray diffraction obtained on a similar probe depth. Our results show, contrary to many previous studies, that the long-term surface stability of ZTA ceramics is preserved. This suggests that the Raman technique does not offer consistent and unique results for the analysis of surface degradation. Moreover, we discuss here that tetragonal-to-monoclinic transformation is also necessary to limit contact damage and wear stripe extension. Thus, the surface metastability of zirconia-containing ceramics may be a non-issue.

scholarly journals Activation of the Unfolded Protein Response with the First-in-Class P97 Inhibitor CB-5083 Induces Stable Disease Regression and Overcomes Ara-C Resistance in AML

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 1350-1350
Author(s):  
Steffan T. Nawrocki ◽  
Yingchun Han ◽  
Ronan LE Moigne ◽  
Valeria Visconte ◽  
Bartlomiej Przychodzen ◽  
...  
Keyword(s):  
Unfolded Protein Response ◽  
Board Of Directors ◽  
Cell Lines ◽  
Primary Cells ◽  
Advisory Committees ◽  
Unfolded Protein ◽  
The Unfolded Protein Response ◽  
Protein Response

Abstract Acute myeloid leukemia (AML) therapy has remained relatively unchanged for more than 40 years with the majority of patients not achieving long-term remission when treated with currently available agents. Novel strategies are urgently needed to improve outcomes. The constitutive dysregulation of protein synthesis/turnover contributes to disease progression and drug resistance in many forms of cancer including AML. p97 (VCP) is a master regulator of protein turnover that has been implicated in oncogenesis and malignant pathogenesis. CB-5083 is a first-in-class selective and potent orally available inhibitor of p97 that in currently being evaluated in phase I clinical trials in patients with multiple myeloma and advanced solid tumors. To assess the potential benefit of p97 inhibition as a novel approach for AML therapy, we investigated the efficacy, pharmacodynamics (PD), and pharmacokinetics (PK) of CB-5083 in a panel of human AML cell lines with diverse genetic backgrounds, primary AML specimens from both newly diagnosed and relapsed/refractory patients, and xenograft mouse models of AML. In vitro treatment with CB-5083 potently diminished the viability of AML cell lines (n = 7) and primary CD34+ blasts obtained from patients (n = 10) with IC50s significantly below 1 µM (range 200 - 700 nM) in all lines and specimens evaluated to date. Diminished viability was associated with reduced clonogenic survival and increased apoptosis in AML cell lines and primary blasts. In contrast to many conventional and experimental drugs that are less active against primary AML cells than established AML cell lines, primary cells exhibited sensitivity to CB-5083 that was similar to cell lines. Additionally, CB-5083 was highly active in 3 different cell line models of cytarabine resistance and primary cells from refractory AML patients. This suggests that CB-5083 may be effective for patients who are relapsed/refractory to conventional therapy. In vitro PD analyses demonstrated that CB-5083 rapidly triggered the accumulation of ubiquitin-conjugated proteins, activated the unfolded protein response (UPR), disrupted STAT5 signaling, reduced levels of key STAT5 targets including BCL-xL and PIM-2, and induced apoptosis. The pro-apoptotic effects of CB-5083 were associated with activation of the endoplasmic reticulum (ER) resident initiator caspase-4 and induction of the BH3-only protein NOXA, which has been previously demonstrated to be an important mediator of cell death induced by other agents that disrupt protein homeostasis. RNA sequencing (RNASeq) gene ontology (GO) analyses of MV4-11 and MOLM-13 AML cells following treatment with CB-5083 demonstrated that short-term treatment (6h) caused significant increases in multiple regulators of the unfolded protein response, protein biosynthesis, and other ubiquitin-related pathways (p<0.001). Results were confirmed by qRT-PCR. The in vivo anti-leukemic activity of CB-5083 was investigated in two different xenograft mouse models of AML: the FLT3-ITD+ MV4-11 cell line and APML HL-60 cells. Oral administration of CB-5083 (once daily, 4 days on, 3 days off) was well tolerated and induced disease regression in both xenograft models (p<0.01). In vivo PD studies demonstrated that administration of CB-5083 led to reduced AML cell proliferation (PCNA), to the induction of apoptosis (active caspase-3), and pathway inhibition as evidenced by poly-ubiquitin accumulation and elevated expression of CHOP, GRP78, and NOXA. PK-PD analyses demonstrated a correlation between the kinetics of the in vivo PD effects and drug exposure. Our collective preclinical data demonstrate that p97 inhibition is a very effective novel anti-leukemic strategy and support clinical investigation of CB-5083 in patients with relapsed/refractory AML. Disclosures LE Moigne: Cleave Biosciences: Employment. Rolfe:Cleave Biosciences: Employment. Djakovic:Cleave Biosciences: Employment. Anderson:Cleave Biosciences: Employment. Wustrow:Cleave Biosciences: Employment. Zhou:Cleave Biosciences: Employment. Wong:Cleave Biosciences: Employment. Sekeres:TetraLogic: Membership on an entity's Board of Directors or advisory committees; Celgene Corporation: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees. Carew:Boehringer Ingelheim: Research Funding.

scholarly journals Leukemia-Associated HSC Vascular Niche Is Negatively Regulated By PERK of Unfolded Protein Response (UPR)

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 2486-2486
Author(s):  
Lan Zhou ◽  
Cui Liu ◽  
Stanley A Adoro ◽  
Lechuang Chen ◽  
Diana Ramirez ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Endothelial Cells ◽  
Er Stress ◽  
Leukemia Cell ◽  
Unfolded Protein ◽  
Vascular Niche ◽  
Activating Transcription Factor ◽  
Protein Response

T cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological malignancy derived from early T cell progenitors. Diffuse infiltration of the bone marrow by T-ALL is associated with worse prognosis. We previously reported that actively proliferating leukemia cells inhibit normal hematopoietic stem and progenitor cell (HSPC) proliferation and homing to the perivascular region. We found that aberrant Notch activation in the stroma plays an important role in negatively regulating the expression of CXLC12 on osteoblasts and their differentiation. However, the underlying molecular mechanism that leads to the suppression of hematopoiesis and decreased HSPC in the vascular niche is unclear. It has been demonstrated that rapid cellular proliferation associated with oncogenic activity such as MYC in T-ALL leads to a global increase in protein synthesis and an increase in misfolded/unfolded polypeptides in the endoplasmic reticulum (ER), referred to as unfolded protein response (UPR) or ER stress. Elevated ER stress leads to activation of at least three types of ER stress transducers through the release of inhibitory binding by glucose-regulated chaperone protein (GRP78/BIP): the protein kinase RNA-like ER kinase (PERK), the inositol-requiring enzyme 1 (IRE1), and the activating transcription factor 6 (ATF6). Activation of PERK phosphorylates eIF2 to repress global translation with the exception of a small number of proteins including ATF4 (activating transcription factor-4). ATF4 regulates genes involved in restoring ER homeostasis and genes in apoptosis. Here, we studied the role of UPR in the regulation of HSC niche function in the setting of T-ALL progression. Using in vitro assays in which T-ALL leukemia cells driven by activated Notch1 (ICN1) were co-cultured with endothelial cells (MILE SVEN 1, MS1), and in vivo ICN1-driven T-ALL model, we found that PERK-eIF2a-ATF4 pathway was activated in both MS1 cells and BM endothelial cells isolated from T-ALL mice, while IRE1 and ATF6 pathways were only mildly altered. The activation of PERK was accompanied with the increased expression of Jagged1 and suppressed expression of CXCL12 in both cultured endothelial cells and bone marrow endothelial cells from leukemia mice. PERK inhibitor (GSK2606414) treatment of co-cultured cells largely restored CXCL12 expression, which was also negatively regulated by Jagged1, and accelerated the leukemia cell apoptosis as indicated by the enhanced annexin staining. These findings suggest that PERK is the upstream regulator of Jagged1 and CXCL12 in the endothelial cells; however, the function of cell-autonomous PERK on leukemia cell survival needs to be further clarified. To understand the role of PERK in bone marrow endothelium during leukemia development in vivo, we examined T-ALL leukemia progression and its effect on vascular niche function in VE-CadherinERT2/PERKF/F mice in which Perk was specifically deleted in endothelial cells. Consistent with in vitro findings, T-ALL development induced endothelial PERK-eIF2a-ATF4 activation, while up-regulated Jagged1 and down-regulated CXCL12 were also identified in isolated BM endothelial cells. Compared to the wild type mice, VE-CadherinERT2/PERKF/F mice showed attenuated leukemia progression, increased HSPC (Lin-Sca-1+c-kit+) frequency, and improved survival. Taken together, our findings suggest that PERK activation in BM endothelial cells is a key regulator of the leukemia vascular niche to promote leukemia progression and to suppress normal hematopoiesis. Therefore, targeting PERK may offer an effective strategy in restoring normal HSPC homeostasis and limiting leukemia progression. Disclosures No relevant conflicts of interest to declare.

scholarly journals Unfolded Protein Response and Crohn’s Diseases: A Molecular Mechanism of Wound Healing in the Gut

2021 ◽  
Author(s):  
Chao Li
Keyword(s):  
Er Stress ◽  
Unfolded Protein Response ◽  
Immune Cell ◽  
Macrophage Polarization ◽  
Intestinal Epithelial ◽  
Unfolded Protein ◽  
The Unfolded Protein Response ◽  
Protein Response

Endoplasmic reticulum (ER) stress triggers a series of signaling and transcriptional events termed the unfolded protein response (UPR). Severe ER stress is associated with the development of fibrosis in different organs including lung, liver, kidney, heart, and intestine. ER stress is an essential response of epithelial and immune cells in the pathogenesis of inflammatory bowel disease (IBD) including Crohn&rsquo;s disease. Intestinal epithelial cells are susceptible to ER stress-mediated damage due to secretion of a large amount of proteins that are involved in mucosal defense. In other cells, ER stress is linked to myofibroblast activation, extracellular matrix production, macrophage polarization, and immune cell differentiation. This review focuses on the role of UPR in the pathogenesis in IBD from an immunologic perspective. The roles of macrophage and mesenchymal cells in the UPR from in vitro and in vivo animal models are discussed. The links between ER stress and other signaling pathways such as senescence and autophagy are introduced. Recent advances in the understanding of the epigenetic regulation of UPR signaling are also updated here. The future directions of development of the UPR research and therapeutic strategies to manipulate ER stress levels are also reviewed.

scholarly journals P09.14 Blocking counterregulation of unfolded protein response by targeted protein synthesis inhibition produces highly synergistic cell death in several cancer entities

2020 ◽  
Vol 8 (Suppl 2) ◽  
pp. A59.1-A59
Author(s):  
F Gsottberger ◽  
C Meier ◽  
S Petkovic ◽  
L Mellenthin ◽  
M Krumbholz ◽  
...  
Keyword(s):  
Cell Death ◽  
Protein Synthesis ◽  
Unfolded Protein Response ◽  
Therapeutic Window ◽  
Protein Synthesis Inhibition ◽  
Synthesis Inhibition ◽  
Unfolded Protein ◽  
Protein Response

BackgroundBecause tumor cells have high proliferation rates the demand for energy on the one hand and proteins on the other hand is high. In line, protein folding machinery of the ER is heavily used. 2-Deoxyglucose (2-DG) not only blocks energy synthesis by inhibiting glycolysis but also blocks synthesis of mannosyl leading to impaired N-linked glycosylation, accumulation of misfolded proteins, and increased unfolded protein response (UPR). However, due to compensatory events, UPR-induced apoptosis is hampered. Therefore, we combined 2-DG with targeted protein synthesis inhibition by immunotoxins, consisting of an antibody and pseudomonas exotoxin, to enhance UPR mediated cell death.Materials and MethodsEstablished cell lines and patient-derived B-ALL samples were treated in vitro with various protein synthesis inhibitors and UPR-inducers. Drug synergy was determined mathematically as fold-increase over additivity. Biochemical studies were performed using western blots. In vivo enhancement was tested using systemic xenograft models.ResultsThe combination of Moxetumomab and 2-DG achieved a two to nine-fold synergy in vitro. Synergy was abrogated by the addition of Mannose suggesting UPR as cause of synergistic cell death. Similarly, Moxetumomab enhanced UPR-inducers Bortezomib and tunicamycin and protein synthesis inhibition by cycloheximide and puromycin enhanced 2-DG suggesting a conserved mechanism. Using HB21, an immunotoxin targeting human transferrin-receptor, breast cancer, hepatocellular carcinoma, and glioblastoma were sensitized to 2-DG induced cell death. Biochemically, 2-DG increased XBP-1-cleavage, expression of pro-apoptotic CHOP and of anti-apoptotic BIP. Moxetumomab, however, blocked the upregulation of BIP while maintaining CHOP correlating with synergistic increase in PARP-cleavage and apoptosis. In two systemic mouse models, bone marrow (BM) lymphoma infiltration was not reduced by 2-DG or tunicamycin alone but was reduced after treatment with Moxetumomab alone by 5-fold in the JeKo-1 and by 16-fold in the Ramos model, respectively. The combination of Moxetumomab and 2-DG achieved a three-fold synergy in the JeKo-1 model and achieved MRD-negative BM status in the Ramos model. Against patient-derived B-ALL of the Burkitt’s type, 2-DG and Moxetumomab were up to 5-fold more active in vitro and up to 7-fold more active in mouse xenografts in vivo.ConclusionsCell death after persisting unfolded protein response is synergistically enhanced by tumor-cell specific inhibition of protein synthesis against four distinct tumor entities at physiologically achievable concentrations. Our approach of immunotoxin-induced targeted protein synthesis inhibition opens a novel, so far undescribed therapeutic window which may warrant clinical evaluation.Disclosure InformationF. Gsottberger: None. C. Meier: None. S. Petkovic: None. L. Mellenthin: None. M. Krumbholz: None. M. Metzler: None. A. Mackensen: None. F. Müller: None.

scholarly journals Dominant negative FADD dissipates the proapoptotic signalosome of the unfolded protein response in diabetic embryopathy

2015 ◽  
Vol 309 (10) ◽  
pp. E861-E873 ◽  
Author(s):  
Fang Wang ◽  
Hongbo Weng ◽  
Michael J. Quon ◽  
Jingwen Yu ◽  
Jian-Ying Wang ◽  
...  
Keyword(s):  
Er Stress ◽  
Unfolded Protein Response ◽  
High Glucose ◽  
Dominant Negative ◽  
Caspase 8 ◽  
Death Domain ◽  
Unfolded Protein ◽  
Protein Response

Endoplasmic reticulum (ER) stress and caspase 8-dependent apoptosis are two interlinked causal events in maternal diabetes-induced neural tube defects (NTDs). The inositol-requiring enzyme 1α (IRE1α) signalosome mediates the proapoptotic effect of ER stress. Diabetes increases tumor necrosis factor receptor type 1R-associated death domain (TRADD) expression. Here, we revealed two new unfolded protein response (UPR) regulators, TRADD and Fas-associated protein with death domain (FADD). TRADD interacted with both the IRE1α-TRAF2-ASK1 complex and FADD. In vivo overexpression of a FADD dominant negative (FADD-DN) mutant lacking the death effector domain disrupted diabetes-induced IRE1α signalosome and suppressed ER stress and caspase 8-dependent apoptosis, leading to NTD prevention. FADD-DN abrogated ER stress markers and blocked the JNK1/2-ASK1 pathway. Diabetes-induced mitochondrial translocation of proapoptotic Bcl-2 members mitochondrial dysfunction and caspase cleavage were also alleviated by FADD-DN. In vitro TRADD overexpression triggered UPR and ER stress before manifestation of caspase 3 and caspase 8 cleavage and apoptosis. FADD-DN overexpression repressed high glucose- or TRADD overexpression-induced IRE1α phosphorylation, its downstream proapoptotic kinase activation and endonuclease activities, and apoptosis. FADD-DN also attenuated tunicamycin-induced UPR and ER stress. These findings suggest that TRADD participates in the IRE1α signalosome and induces UPR and ER stress and that the association between TRADD and FADD is essential for diabetes- or high glucose-induced UPR and ER stress.

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