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Prashanth K B Nagesh, Elham Hatami, Pallabita Chowdhury, Vivek K Kashyap, Sheema Khan, Bilal B Hafeez, Subhash C Chauhan, Meena Jaggi, Murali M Yallapu
Endoplasmic reticulum (ER) stress is an intriguing target with significant clinical importance in chemotherapy. Interference with ER functions can lead to the accumulation of unfolded proteins, as detected by transmembrane sensors that instigate the unfolded protein response (UPR). Therefore, controlling induced UPR via ER stress with natural compounds could be a novel therapeutic strategy for the management of prostate cancer. Tannic acid (a naturally occurring polyphenol) was used to examine the ER stress mediated UPR pathway in prostate cancer cells...
March 7, 2018: Cancers
Ganesh M Nawkar, Eun Seon Lee, Rahul M Shelake, Joung Hun Park, Seoung Woo Ryu, Chang Ho Kang, Sang Yeol Lee
Maintenance of homeostasis of the endoplasmic reticulum (ER) ensures the balance between loading of nascent proteins and their secretion. Certain developmental conditions or environmental stressors affect protein folding causing ER stress. The resultant ER stress is mitigated by upregulating a set of stress-responsive genes in the nucleus modulating the mechanism of the unfolded protein response (UPR). In plants, the UPR is mediated by two major pathways; by the proteolytic processing of bZIP17/28 and by the IRE1-mediated splicing of bZIP60 mRNA...
2018: Frontiers in Plant Science
Yanfang Wu, Xia Li, Junying Jia, Yanpeng Zhang, Jing Li, Zhengmao Zhu, Huaqing Wang, Jie Tang, Junjie Hu
The accumulation of misfolded proteins in the endoplasmic reticulum (ER) causes ER stress and triggers the unfolded protein response (UPR). Failure to resolve ER stress leads to apoptotic cell death via a yet unclear mechanism. Here, we show that RNF183, a membrane-spanning RING finger protein, localizes to the ER and exhibits classic E3 ligase activities. Sustained ER stress induced by different treatments increases RNF183 protein levels posttranscriptionally in an IRE1α-dependent manner. Activated IRE1 reduces the level of miR-7, which increases the stability of RNF183 transcripts...
March 5, 2018: Proceedings of the National Academy of Sciences of the United States of America
Na Zhao, Jin Cao, Longyong Xu, Qianzi Tang, Lacey E Dobrolecki, Xiangdong Lv, Manisha Talukdar, Yang Lu, Xiaoran Wang, Dorothy Z Hu, Qing Shi, Yu Xiang, Yunfei Wang, Xia Liu, Wen Bu, Yi Jiang, Mingzhou Li, Yingyun Gong, Zheng Sun, Haoqiang Ying, Bo Yuan, Xia Lin, Xin-Hua Feng, Sean M Hartig, Feng Li, Haifa Shen, Yiwen Chen, Leng Han, Qingping Zeng, John B Patterson, Benny Abraham Kaipparettu, Nagireddy Putluri, Frank Sicheri, Jeffrey M Rosen, Michael T Lewis, Xi Chen
The unfolded protein response (UPR) is a cellular homeostatic mechanism that is activated in many human cancers and plays pivotal roles in tumor progression and therapy resistance. However, the molecular mechanisms for UPR activation and regulation in cancer cells remain elusive. Here, we show that oncogenic MYC regulates the inositol-requiring enzyme 1 (IRE1)/X-box binding protein 1 (XBP1) branch of the UPR in breast cancer via multiple mechanisms. We found that MYC directly controls IRE1 transcription by binding to its promoter and enhancer...
February 26, 2018: Journal of Clinical Investigation
Daniel Hughes, Giovanna R Mallucci
The unfolded protein response (UPR) is a highly conserved protein quality control mechanism, activated in response to Endoplasmic Reticulum (ER) stress. Signaling is mediated through three branches, PERK, IRE1 and ATF6, respectively, that together provide a coordinated response that contributes to overcoming disrupted proteostasis. PERK branch activation predominantly causes a rapid reduction in global rates of translation, whilst the IRE1 and ATF6 branch signaling induce a transcriptional response resulting in expression of chaperones and components of the protein degradation machinery...
February 24, 2018: FEBS Journal
Man Liu, Guangbin Shi, Anyu Zhou, Cassady E Rupert, Kareen L K Coulombe, Samuel C Dudley
RATIONALE: Heart failure is characterized by electrical remodeling that contributes to arrhythmic risk. The unfolded protein response (UPR) is active in heart failure and can decrease protein levels by increasing mRNA decay, accelerating protein degradation, and inhibiting protein translation. OBJECTIVE: Therefore, we investigated whether the UPR downregulated cardiac ion channels that may contribute to arrhythmogenic electrical remodeling. METHODS: Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) were used to study cardiac ion channels...
February 21, 2018: Journal of Molecular and Cellular Cardiology
Stephanie R Harrison, Thomas Scambler, Lylia Oubussad, Chi Wong, Miriam Wittmann, Michael F McDermott, Sinisa Savic
Tumor necrosis factor (TNF)-receptor-associated periodic fever syndrome (TRAPS) is a rare monogenic autoinflammatory disorder characterized by mutations in the TNFRSF1A gene, causing TNF-receptor 1 (TNFR1) misfolding, increased cellular stress, activation of the unfolded protein response (UPR), and hyperresponsiveness to lipopolysaccharide (LPS). Both microRNA (miR)-146a and miR-155 provide negative feedback for LPS-toll-like receptor 2/4 signaling and cytokine production, through regulation of nuclear factor kappa B (NF-κB)...
2018: Frontiers in Immunology
Timothy J Bergmann, Ilaria Fregno, Fiorenza Fumagalli, Andrea Rinaldi, Francesco Bertoni, Paul J Boersema, Paola Picotti, Maurizio Molinari
The stress sensors ATF6, IRE1 and PERK monitor deviations from homeostatic conditions in the endoplasmic reticulum (ER), a protein biogenesis compartment of eukaryotic cells. Their activation elicits unfolded protein responses (UPR) to re-establish proteostasis. UPR have been extensively investigated in cells exposed to chemicals that activate ER stress sensors by perturbing calcium, N-glycans or redox homeostasis. Cell responses to variations in luminal load with unfolded proteins are, in contrast, poorly characterized...
February 16, 2018: Journal of Biological Chemistry
Chi Thanh Mai, Quynh Giang Le, Yuki Ishiwata-Kimata, Hiroshi Takagi, Kenji Kohno, Yukio Kimata
Accumulation of unfolded secretory proteins in the endoplasmic reticulum (ER), namely ER stress, is hazardous to eukaryotic cells and promotes the unfolded protein response (UPR). Ire1 is an ER-located transmembrane protein that senses ER stress and triggers the UPR. According to previous in vitro experiments, 4-phenylbutyrate (4-PBA) works as a chemical molecular chaperone. Since 4-PBA attenuates the UPR in mammalian tissue cultures, this chemical may have clinical potential for restoring ER-stressing conditions...
February 14, 2018: FEMS Yeast Research
Zhifen Yang, Jing Zhang, Dadi Jiang, Purvesh Khatri, David E Solow-Cordero, Diego A S Toesca, Constantinos Koumenis, Nicholas C Denko, Amato J Giaccia, Quynh-Thu Le, Albert C Koong
Activation of the unfolded protein response (UPR) signaling pathways is linked to multiple human diseases including cancer. The inositol-requiring kinase 1 (IRE1)-X-box binding protein 1 (XBP1) pathway is the most evolutionarily conserved of the three major signaling branches of the UPR. Here, we performed a genome-wide siRNA screen to obtain a systematic assessment of genes integrated in the IRE1-XBP1 axis. We monitored the expression of an XBP1-luciferase chimeric protein in which luciferase was fused in-frame with the spliced (active) form of XBP1...
February 9, 2018: Molecular Cancer Research: MCR
Huaqing Cui, Mengsheng Deng, Yonglan Zhang, Fei Yin, Jianhui Liu
Altered proteostasis induced by amyloid peptide aggregation and hyperphosphorylation of tau protein, is a prominent feature of Alzheimer's disease, which highlights the occurrence of endoplasmic reticulum stress and triggers the activation of the unfolded protein response (UPR), a signaling pathway that enforces adaptive programs to sustain proteostasis. In this study, we investigated the role of geniposide in the activation of UPR induced by high glucose in primary cortical neurons. We found that high glucose induced a significant activation of UPR, and geniposide enhanced the effect of high glucose on the phosphorylation of IRE1α, the most conserved UPR signaling branch...
February 9, 2018: Neurochemical Research
Yasuyo Yamaoka, Bae Young Choi, Hanul Kim, Seungjun Shin, Yeongho Kim, Sunghoon Jang, Won-Yong Song, Chung Hyun Cho, Hwan Su Yoon, Kenji Kohno, Youngsook Lee
In many eukaryotes, ER stress activates the unfolded protein response (UPR) via the transmembrane endoribonuclease IRE1 to maintain ER homeostasis. The ER stress response in microalgae has not been studied in detail. Here, we identified Chlamydomonas reinhardtii IRE1 (CrIRE1) and characterized two independent knockdown alleles of this gene. CrIRE1 is similar to IRE1s identified in budding yeast, plants, and humans, in terms of conserved domains, but is different in having the tandem zinc finger domain at the C-terminus...
January 31, 2018: Plant Journal: for Cell and Molecular Biology
Xiu-Mei Li, Jing Liu, Fang-Fang Pan, Dong-Dong Shi, Zhi-Guo Wen, Pei-Long Yang
Up till now, studies have not been conducted on how the combination of Quercetin (Q), Aconitine (A) and apoptosis induction affects human cervical carcinoma HeLa cells. The result of our findings shows that the combination of Q and A (QA) is capable of synergistically inhibiting the proliferation of HeLa cells in a number of concentrations. QA synergistically inhibits the proliferation of MDR1 gene in the HeLa cells. It is concluded based on our result that QA induces apoptosis and ER stress just as QA-induced ER stress pathway may mediate apoptosis by upregulating mRNA expression levels of eIF2α, ATF4, IRE1, XBP1, ATF6, PERK and CHOP in the HeLa cells...
2018: PloS One
Tatiana V Boyko, Rakesh Bam, Dadi Jiang, Zhen Wang, Namrata Bhatia, Misha C Tran, Michael T Longaker, Albert C Koong, George P Yang
Wound healing is characterized by the production of large amounts of protein necessary to replace lost cellular mass and extracellular matrix. The unfolded protein response (UPR) is an important adaptive cellular response to increased protein synthesis. One of the main components of the UPR is IRE1, an endoplasmic reticulum transmembrane protein with endonuclease activity that produces the activated form of the transcription factor XBP1. Using luciferase reporter mice for Xbp1 splicing, we showed that IRE1 was up-regulated during excisional wound healing at the time in wound healing consistent with that of the proliferative phase, when the majority of protein synthesis for cellular proliferation and matrix deposition occurs...
January 8, 2018: Wound Repair and Regeneration
Megan C Kopp, Piotr R Nowak, Natacha Larburu, Christopher J Adams, Maruf Mu Ali
The unfolded protein response (UPR) is a key signaling system that regulates protein homeostasis within the endoplasmic reticulum (ER). The primary step in UPR activation is the detection of misfolded proteins, the mechanism of which is unclear. We have previously suggested an allosteric mechanism for UPR induction (Carrara et al., 2015) based on qualitative pull-down assays. Here, we develop an in vitro Förster resonance energy transfer (FRET) UPR induction assay that quantifies IRE1 luminal domain and BiP association and dissociation upon addition of misfolded proteins...
January 5, 2018: ELife
Karin Eigner, Yüksel Filik, Florian Mark, Birgit Schütz, Günter Klambauer, Richard Moriggl, Markus Hengstschläger, Herbert Stangl, Mario Mikula, Clemens Röhrl
The mechanisms hallmarking melanoma progression are insufficiently understood. Here we studied the impact of the unfolded protein response (UPR) - a signalling cascade playing ambiguous roles in carcinogenesis - in melanoma malignancy. We identified isogenic patient-derived melanoma cell lines harboring BRAFV600E-mutations as a model system to study the role of intrinsic UPR in melanoma progression. We show that the activity of the three effector pathways of the UPR (ATF6, PERK and IRE1) was increased in metastatic compared to non-metastatic cells...
December 13, 2017: Scientific Reports
Niko Amin-Wetzel, Reuben A Saunders, Maarten J Kamphuis, Claudia Rato, Steffen Preissler, Heather P Harding, David Ron
When unfolded proteins accumulate in the endoplasmic reticulum (ER), the unfolded protein response (UPR) increases ER-protein-folding capacity to restore protein-folding homeostasis. Unfolded proteins activate UPR signaling across the ER membrane to the nucleus by promoting oligomerization of IRE1, a conserved transmembrane ER stress receptor. However, the coupling of ER stress to IRE1 oligomerization and activation has remained obscure. Here, we report that the ER luminal co-chaperone ERdj4/DNAJB9 is a selective IRE1 repressor that promotes a complex between the luminal Hsp70 BiP and the luminal stress-sensing domain of IRE1α (IRE1LD )...
December 14, 2017: Cell
Miguel Sanchez-Alvarez, Miguel Angel Del Pozo, Chris Bakal
Inositol Requiring Enzyme-1 (IRE1) is the most conserved transducer of the Unfolded Protein Response (UPR), a surveillance mechanism that ensures homeostasis of the endoplasmic reticulum (ER) in eukaryotes. IRE1 activation orchestrates adaptive responses, including lipid anabolism, metabolic reprogramming, increases in protein folding competency, and ER expansion/remodeling. However, we still know surprisingly little regarding the principles by which this ER transducer is deactivated upon ER stress clearance...
November 28, 2017: Scientific Reports
Wencheng He, Hailuan Xu, Hongchao Gou, Jin Yuan, Jiedan Liao, Yuming Chen, Shuangqi Fan, Baoming Xie, Shaofeng Deng, Yangyi Zhang, Jinding Chen, Mingqiu Zhao
Classical swine fever (CSF) is an OIE-listed, highly contagious animal disease caused by classical swine fever virus (CSFV). The endoplasmic reticulum (ER) is an organelle in which the replication of many RNA viruses takes place. During viral infection, a series of events elicited in cells can destroy the ER homeostasis that cause ER stress and induce an unfolded protein response (UPR). In this study, we demonstrate that ER stress was induced during CSFV infection as several UPR-responsive elements such as XBP1(s), GRP78 and CHOP were up-regulated...
2017: Frontiers in Microbiology
Alexander McQuiston, J Alan Diehl
The unfolded protein response (UPR) is an evolutionarily conserved stress response to intra- and extracellular conditions that disrupt endoplasmic reticulum (ER) protein-folding capacity. The UPR is engaged by a variety of disease conditions, including most cancers as well as both metabolic and neurodegenerative disorders. Three transmembrane transducers-PERK, IRE1, and ATF6-are responsible for activating downstream signaling pathways that mediate the UPR and subsequent stress response pathways. PERK, an ER resident transmembrane protein kinase, initiates both pro-apoptotic and pro-survival signaling pathways...
2017: F1000Research
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