scholarly journals CHOP and IRE1α-XBP1/JNK signaling promote Newcastle Disease Virus induced apoptosis and benefit virus proliferation

2018 ◽  
Author(s):  
Yanrong Li ◽  
Ying Liao ◽  
Qiaona Niu ◽  
Feng Gu ◽  
Yingjie Sun ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Transcription Factors ◽  
Er Stress ◽  
Tumor Cells ◽  
Signaling Cascades ◽  
Jnk Signaling ◽  
Unfolded Protein ◽  
Exogenous Expression ◽  
Induced Apoptosis ◽  
Infected Tumor

ABSTRACTNewcastle disease virus (NDV) causes severe infectious disease in poultry, and selectively kills tumor cells by inducing apoptosis. In this report, we revealed the mechanisms underlying NDV-induced apoptosis via investigation of endoplasmic reticulum (ER) stress-related unfolded protein response (UPR) in HeLa cells. We found that NDV infection induced the expression of pro-apoptotic transcription factor CHOP via PKR-eIF2α pathway. Knock down and exogenous expression studies showed that CHOP promoted cell apoptosis by down-regulation of anti-apoptotic protein BCL-2 and MCL-1, promotion of pro-apoptotic JNK and p38 signaling, and suppression of pro-survival AKT signaling. Meanwhile, CHOP facilitated NDV proliferation. Furthermore, virus infection activated IRE1α, another ER stress sensor, thereby promoting the mRNA splicing of XBP1 and resulting in the translation of transcription factor XBP1s. XBP1s entered into cell nucleus, promoted the expression of ER chaperones and components of ER associated degradation (ERAD). Exogenous expression of XBP1s helped IBV proliferation, and silence of XBP1s reduced virus proliferation. Meanwhile, exogenous expression and knock down studies demonstrated that IRE1α activated pro-apoptotic JNK signaling, promoted apoptosis and inflammation. In conclusion, our current study demonstrates that the induction of CHOP and activation of IRE1α-XBP1/JNK signaling cascades promote apoptosis and benefit NDV proliferation.IMPORTANCEIt is well known that NDV kills host animal and tumor cells by inducing cell apoptosis. Although several studies investigate the apoptotic phenomena in NDV-infected tumor cells, the molecular mechanisms underlying this oncolytic virus induced apoptosis is not well understood yet. In this study, we focus on characterization of the ER stress responses in NDV-infected tumor cells, and find that virus induces apoptosis by up-regulation or activation of several unfolded protein responses (UPR) related transcription factors and signaling: such as ATF4, CHOP and XBP1s, and pro-apoptotic kinases (IRE1α, JNK, p38). Moreover, activation of these transcription factors and signaling cascades helps virus proliferation. Our study dissects the UPR induced apoptosis in NDV-infected tumor cells, and provides the evidence that UPR favors NDV proliferation.

Are cachexia-associated tumors transmitTERS of ER stress?

2021 ◽  
Author(s):  
Ana Sayuri Yamagata ◽  
Paula Paccielli Freire
Keyword(s):  
Er Stress ◽  
Tumor Cells ◽  
Cancer Cachexia ◽  
Genotoxic Stress ◽  
Unfolded Protein ◽  
Response To Chemotherapy ◽  
The Unfolded Protein Response ◽  
Protein Response ◽  
Associated Tumors

Cancer cachexia is associated with deficient response to chemotherapy. On the other hand, the tumors of cachectic patients remarkably express more chemokines and have higher immune infiltration. For immunogenicity, a strong induction of the unfolded protein response (UPR) is necessary. UPR followed by cell surface exposure of calreticulin on the dying tumor cell is essential for its engulfment by macrophages and dendritic cells. However, some tumor cells upon endoplasmic reticulum (ER) stress can release factors that induce ER stress to other cells, in the so-called transmissible ER stress (TERS). The cells that received TERS produce more interleukin 6 (IL-6) and chemokines and acquire resistance to subsequent ER stress, nutrient deprivation, and genotoxic stress. Since ER stress enhances the release of extracellular vesicles (EVs), we suggest they can mediate TERS. It was found that ER stressed cachexia-inducing tumor cells transmit factors that trigger ER stress in other cells. Therefore, considering the role of EVs in cancer cachexia, the release of exosomes can possibly play a role in the process of blunting the immunogenicity of the cachexia-associated tumors. We propose that TERS can cause an inflammatory and immunosuppressive phenotype in cachexia-inducing tumors.

scholarly journals Identification of MEF2-regulated genes during muscle differentiation

2004 ◽  
Vol 20 (1) ◽  
pp. 143-151 ◽  
Author(s):  
James Paris ◽  
Carl Virtanen ◽  
Zhibin Lu ◽  
Mark Takahashi
Keyword(s):  
Gene Regulation ◽  
Transcription Factor ◽  
Transcription Factors ◽  
Neuromuscular Junctions ◽  
Muscle Differentiation ◽  
Signaling Cascades ◽  
Specific Gene ◽  
Genetic Mechanisms ◽  
Selection Parameters ◽  
First Time

Although a great deal has been elucidated concerning the mechanisms regulating muscle differentiation, little is known about transcription factor-specific gene regulation. Our understanding of the genetic mechanisms regulating cell differentiation is quite limited. Much of what has been defined centers on regulatory signaling cascades and transcription factors. Surprisingly few studies have investigated the association of genes with specific transcription factors. To address these issues, we have utilized a method coupling chromatin immunoprecipitation and CpG microarrays to characterize the genes associated with MEF2 in differentiating C2C12 cells. Results demonstrated a defined binding pattern over the course of differentiation. Filtered data demonstrated 9 clones to be elevated at 0 h, 792 at 6 h, 163 by 1 day, and 316 at 3 days. Using unbiased selection parameters, we selected a subset of 291 prospective candidates. Clones were sequenced and filtered for removal of redundancy between clones and for the presence of repetitive elements. We were able to place 50 of these on the mouse genome, and 20 were found to be located near well-annotated genes. From this list, previously undefined associations with MEF2 were discovered. Many of these genes represent proteins involved in neurogenesis, neuromuscular junctions, signaling and metabolism. The remaining clones include many full-length cDNA and represent novel gene targets. The results of this study provides for the first time, a unique look at gene regulation at the level of transcription factor binding in differentiating muscle.

scholarly journals RIPK1 promotes death receptor-independent caspase-8-mediated apoptosis under unresolved ER stress conditions

2014 ◽  
Vol 5 (12) ◽  
pp. e1555-e1555 ◽  
Author(s):  
Y Estornes ◽  
M A Aguileta ◽  
C Dubuisson ◽  
J De Keyser ◽  
V Goossens ◽  
...  
Keyword(s):  
Er Stress ◽  
Molecular Mechanisms ◽  
Death Receptor ◽  
Caspase 8 ◽  
Interacting Protein ◽  
Life And Death ◽  
Unfolded Protein ◽  
Induced Apoptosis ◽  
The Unfolded Protein Response ◽  
Protein Response

Abstract Accumulation of unfolded proteins in the endoplasmic reticulum (ER) causes ER stress and results in the activation of the unfolded protein response (UPR), which aims at restoring ER homeostasis. However, when the stress is too severe the UPR switches from being a pro-survival response to a pro-death one, and the molecular mechanisms underlying ER stress-mediated death have remained incompletely understood. In this study, we identified receptor interacting protein kinase 1 (RIPK1)—a kinase at the crossroad between life and death downstream of various receptors—as a new regulator of ER stress-induced death. We found that Ripk1-deficient MEFs are protected from apoptosis induced by ER stressors, which is reflected by reduced caspase activation and PARP processing. Interestingly, the pro-apoptotic role of Ripk1 is independent of its kinase activity, is not regulated by its cIAP1/2-mediated ubiquitylation, and does not rely on the direct regulation of JNK or CHOP, two reportedly main players in ER stress-induced death. Instead, we found that ER stress-induced apoptosis in these cells relies on death receptor-independent activation of caspase-8, and identified Ripk1 upstream of caspase-8. However, in contrast to RIPK1-dependent apoptosis downstream of TNFR1, we did not find Ripk1 associated with caspase-8 in a death-inducing complex upon unresolved ER stress. Our data rather suggest that RIPK1 indirectly regulates caspase-8 activation, in part via interaction with the ER stress sensor inositol-requiring protein 1 (IRE1).

scholarly journals Effect of aging on UVC-induced apoptosis of rat splenocytes.

2000 ◽  
Vol 47 (2) ◽  
pp. 339-347 ◽  
Author(s):  
E Radziszewska ◽  
K Piwocka ◽  
A Bielak-Zmijewska ◽  
J Skierski ◽  
E Sikora
Keyword(s):  
Transcription Factor ◽  
Transcription Factors ◽  
Morphological Changes ◽  
Transcription Factor Activity ◽  
Factor Activity ◽  
Dna Ladder ◽  
Young Rats ◽  
Bax Protein ◽  
Old Rats ◽  
Induced Apoptosis

UVC-induced apoptotic symptoms such as morphological changes, DNA fragmentation, Bcl-2 and Bax protein expression were examined in primary splenocyte cultures from young (3 months) and old (24 months) rats. The activities of AP-1 and CRE transcription factors in UVC-irradiated splenocytes were also assessed. At 24 h after UVC irradiation 40% of cells derived from young rats were found to be apoptotic, which was twice as much as in splenocytes from old rats. Apoptosis in cells from old rats did not give typical symptoms like a "DNA ladder" and Bcl-2 protein downregulation, in contrast to splenocytes from young rats. No AP-1 transcription factor activity was found in UVC-irradiated splenocytes from old animals and only a trace activity in splenocytes from young animals. This indicates that, UVC-induced apoptosis in rat splenocytes is practically AP-1 independent and that cells from old rats are less sensitive to UVC irradiation than splenocytes from young rats.

scholarly journals Unification of Opposites between Two Antioxidant Transcription Factors Nrf1 and Nrf2 in Mediating Distinct Cellular Responses to the Endoplasmic Reticulum Stressor Tunicamycin

Antioxidants ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 4 ◽  
Author(s):  
Yu-ping Zhu ◽  
Ze Zheng ◽  
Shaofan Hu ◽  
Xufang Ru ◽  
Zhuo Fan ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Transcription Factor ◽  
Transcription Factors ◽  
Er Stress ◽  
Target Genes ◽  
Cellular Responses ◽  
Water Soluble ◽  
Heme Oxygenase 1 ◽  
Nuclear Factor ◽  
Activating Transcription Factor

The water-soluble Nrf2 (nuclear factor, erythroid 2-like 2, also called Nfe2l2) is accepted as a master regulator of antioxidant responses to cellular stress, and it was also identified as a direct target of the endoplasmic reticulum (ER)-anchored PERK (protein kinase RNA-like endoplasmic reticulum kinase). However, the membrane-bound Nrf1 (nuclear factor, erythroid 2-like 1, also called Nfe2l1) response to ER stress remains elusive. Herein, we report a unity of opposites between these two antioxidant transcription factors, Nrf1 and Nrf2, in coordinating distinct cellular responses to the ER stressor tunicamycin (TU). The TU-inducible transcription of Nrf1 and Nrf2, as well as GCLM (glutamate cysteine ligase modifier subunit) and HO-1 (heme oxygenase 1), was accompanied by activation of ER stress signaling networks. Notably, the unfolded protein response (UPR) mediated by ATF6 (activating transcription factor 6), IRE1 (inositol requiring enzyme 1) and PERK was significantly suppressed by Nrf1α-specific knockout, but hyper-expression of Nrf2 and its target genes GCLM and HO-1 has retained in Nrf1α−/− cells. By contrast, Nrf2−/−ΔTA cells with genomic deletion of its transactivation (TA) domain resulted in significant decreases of GCLM, HO-1 and Nrf1; this was accompanied by partial decreases of IRE1 and ATF6, rather than PERK, but with an increase of ATF4 (activating transcription factor 4). Interestingly, Nrf1 glycosylation and its trans-activity to mediate the transcriptional expression of the 26S proteasomal subunits, were repressed by TU. This inhibitory effect was enhanced by Nrf1α−/− and Nrf2−/−ΔTA, but not by a constitutive activator caNrf2ΔN (that increased abundances of the non-glycosylated and processed Nrf1). Furthermore, caNrf2ΔN also enhanced induction of PERK and IRE1 by TU, but reduced expression of ATF4 and HO-1. Thus, it is inferred that such distinct roles of Nrf1 and Nrf2 are unified to maintain cell homeostasis by a series of coordinated ER-to-nuclear signaling responses to TU. Nrf1α (i.e., a full-length form) acts in a cell-autonomous manner to determine the transcription of most of UPR-target genes, albeit Nrf2 is also partially involved in this process. Consistently, transactivation of ARE (antioxidant response element)-driven BIP (binding immunoglobulin protein)-, PERK- and XBP1 (X-box binding protein 1)-Luc reporter genes was mediated directly by Nrf1 and/or Nrf2. Interestingly, Nrf1α is more potent than Nrf2 at mediating the cytoprotective responses against the cytotoxicity of TU alone or plus tBHQ (tert-butylhydroquinone). This is also further supported by the evidence that the intracellular reactive oxygen species (ROS) levels are increased in Nrf1α−/− cells, but rather are, to our surprise, decreased in Nrf2−/−ΔTA cells.

scholarly journals Ceapins are a new class of unfolded protein response inhibitors, selectively targeting the ATF6α branch

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Ciara M Gallagher ◽  
Carolina Garri ◽  
Erica L Cain ◽  
Kenny Kean-Hooi Ang ◽  
Christopher G Wilson ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Er Stress ◽  
Unfolded Protein Response ◽  
Proteolytic Processing ◽  
Unfolded Protein ◽  
New Class ◽  
Cancer Models ◽  
Membrane Bound ◽  
The Unfolded Protein Response ◽  
Protein Response

The membrane-bound transcription factor ATF6α plays a cytoprotective role in the unfolded protein response (UPR), required for cells to survive ER stress. Activation of ATF6α promotes cell survival in cancer models. We used cell-based screens to discover and develop Ceapins, a class of pyrazole amides, that block ATF6α signaling in response to ER stress. Ceapins sensitize cells to ER stress without impacting viability of unstressed cells. Ceapins are highly specific inhibitors of ATF6α signaling, not affecting signaling through the other branches of the UPR, or proteolytic processing of its close homolog ATF6β or SREBP (a cholesterol-regulated transcription factor), both activated by the same proteases. Ceapins are first-in-class inhibitors that can be used to explore both the mechanism of activation of ATF6α and its role in pathological settings. The discovery of Ceapins now enables pharmacological modulation all three UPR branches either singly or in combination.

scholarly journals The unfolded protein response controls ER stress-induced apoptosis of lung epithelial cells through angiotensin generation

2016 ◽  
Vol 311 (5) ◽  
pp. L846-L854 ◽  
Author(s):  
Hang Nguyen ◽  
Bruce D. Uhal
Keyword(s):  
Epithelial Cells ◽  
Er Stress ◽  
Unfolded Protein Response ◽  
Cathepsin D ◽  
Lung Epithelial Cells ◽  
Chemical Chaperone ◽  
Unfolded Protein ◽  
Induced Apoptosis ◽  
The Unfolded Protein Response ◽  
Protein Response

Recent work from this laboratory showed that endoplasmic reticulum (ER) stress-induced apoptosis of alveolar epithelial cells (AECs) is regulated by the autocrine angiotensin (ANG)II/ANG1-7 system. The proteasome inhibitor MG132 or surfactant protein C (SP-C) BRICHOS domain mutation G100S induced apoptosis in human AECs by activating the proapoptotic cathepsin D and reducing antiapoptotic angiotensin converting enzyme-2 (ACE-2). This study tested the hypothesis that ER stress-induced apoptosis of human AECs might be mediated by influence of the unfolded protein response (UPR) on the autocrine ANGII/ANG1-7 system. A549 cells were challenged with MG132 or SP-C BRICHOS domain mutant G100S to induce ER stress and activation of UPR pathways. The results showed that either MG132 or G100S SP-C mutation activated all three canonical pathways of the UPR (IRE1/XBP1, ATF6, and PERK/eIF2α), which led to a significant increase in cathepsin D or in TACE (an ACE-2 ectodomain shedding enzyme) and eventually caused AEC apoptosis. However, ER stress-induced AEC apoptosis could be prevented by chemical chaperone or by UPR blockers. It is also suggested that ATF6 and IRE1 pathways might play important role in regulation of angiotensin system. These data demonstrate that ER stress induces apoptosis in human AECs through mediation of UPR pathways, which in turn regulate the autocrine ANGII/ANG1-7 system. They also demonstrated that ER stress-induced AEC apoptosis can be blocked by inhibition of UPR signaling pathways.

scholarly journals Activation of the ATF6 branch of the unfolded protein response in neurons improves stroke outcome

2016 ◽  
Vol 37 (3) ◽  
pp. 1069-1079 ◽  
Author(s):  
Zhui Yu ◽  
Huaxin Sheng ◽  
Shuai Liu ◽  
Shengli Zhao ◽  
Christopher C Glembotski ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Er Stress ◽  
Unfolded Protein Response ◽  
Short Form ◽  
Infarct Volume ◽  
Stroke Outcome ◽  
Early Reperfusion ◽  
Unfolded Protein ◽  
The Unfolded Protein Response ◽  
Protein Response

Impaired function of the endoplasmic reticulum (ER stress) is a hallmark of many human diseases including stroke. To restore ER function in stressed cells, the unfolded protein response (UPR) is induced, which activates 3 ER stress sensor proteins including activating transcription factor 6 (ATF6). ATF6 is then cleaved by proteases to form the short-form ATF6 (sATF6), a transcription factor. To determine the extent to which activation of the ATF6 UPR branch defines the fate and function of neurons after stroke, we generated a conditional and tamoxifen-inducible sATF6 knock-in mouse. To express sATF6 in forebrain neurons, we crossed our sATF6 knock-in mouse line with Emx1-Cre mice to generate ATF6-KI mice. After the ATF6 branch was activated in ATF6-KI mice with tamoxifen, mice were subjected to transient middle cerebral artery occlusion. Forced activation of the ATF6 UPR branch reduced infarct volume and improved functional outcome at 24 h after stroke. Increased autophagic activity at early reperfusion time after stroke may contribute to the ATF6-mediated neuroprotection. We concluded that the ATF6 UPR branch is crucial to ischemic stroke outcome. Therefore, boosting UPR pro-survival pathways may be a promising therapeutic strategy for stroke.

Effects of EGF-R on Transcription Factor Activation in Hematopoietic Cells: EGF-R Activates Multiple Transcription Factors Which Induce Proliferation in the Absence of Autocrine Cytokines.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 4185-4185
Author(s):  
John G. Shelton ◽  
Linda S. Steelman ◽  
Martin McMahon ◽  
James A. McCubrey
Keyword(s):  
Transcription Factor ◽  
Transcription Factors ◽  
Kinase Inhibitors ◽  
Hematopoietic Cells ◽  
Growth Factor Receptor ◽  
Biological Properties ◽  
Small Molecular Weight ◽  
Erythroid Progenitor ◽  
Jnk Inhibitors ◽  
Induced Apoptosis

Abstract v-ErbB is an oncogene related to the Epidermal Growth Factor Receptor (EGF-R) that was initially discovered in the genome of avian erythoblastosis virus. v-ErbB will abrogate the requirement of erythroid progenitor cells for erythropoietin and stem cell factor and block terminal differentiation. EGF-R overexpression has been observed in many pathological situations and the EGF-R gene is amplified in certain tumors. Moreover, there is a truncated form of EGF-R referred to as EGFvIII which resembles v-ErbB in biological properties. One problem frequently encountered in studying the effects of EGF-R overexpression in many tumors is that EGF-R expression is often constitutive and in the presence of increased expression of other oncogenes or in the absence of certain tumor suppressor genes. To circumvent these problems, we subcloned v-ErbB into a vector which contained the estrogen receptor hormone binding domain which renders the v-ErbB protein dependent upon the addition of beta-estradiol or 4 OH tamoxifen for activity. The v-ErbB:ER oncogene will conditionally abrogate the cytokine dependence of human (TF-1) and murine (FL5.12 and FDC-P1) hematopoietic cells efficiently. This construct has allowed us to examine the transcription factors pathways activated by v-ErbB:ER in hematopoietic cells which are required for proliferation in the absence of previously required cytokines. By determining which signal transduction pathways were activated in response to either v-ErbB:ER activation or IL-3 addition in the presence and absence of specific small molecular weight membrane permeable kinase inhibitors, we could ascertain that v-ErbB:ER expression activated the STAT5, Elk, CREB, Jun, and Forkhead (Foxo) family of transcription factors in FL/v-ErbB:ER cells. The activation of these transcription factors was blocked by the respective kinase inhibitors. Thus v-ErbB:ER activated a broad spectrum of transcription factors. Treatment of v-ErbB:ER cells with the EGF-R inhibitor AG1478 very efficiently induced apoptosis in these cells at 100 to 1000 fold lower concentrations than MEK, PI3K or JNK inhibitors and activation of all these transcription factor inhibitors was inhibited. In contrast, when the cells were treated with MEK, PI3K or JNK inhibitors, only the transcription factors specific for the individual pathways were inhibited. FL5.12 cells conditionally transformed to grow in response to activated Raf and Akt, (FL/Akt:ER+Raf-1:AR) were also isolated. Activation of STAT5 by either Raf or Akt did not occur in FL/Akt:ER+Raf-1:AR cells, but did occur when the cells were treated with IL-3. Furthermore, Elk activation occurred in response to Raf activation but not IL-3 stimulation in the FL/Akt:ER+Raf-1:AR cells which grew in response to Raf and Akt. Thus oncogenes such as v-ErbB:ER, which are more effective in their ability to transform hematopoietic cells than oncogenes such as Raf and Akt, can induce multiple transcription factors, only some of which are required for growth in tissue culture systems.

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