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Scott A Oakes
The unfolded protein response (UPR) is an intracellular signaling network largely controlled by three endoplasmic reticulum (ER) transmembrane proteins-IRE1, PERK, and ATF6-that monitors the protein folding status of the ER and initiates corrective measures to maintain ER homeostasis. Hypoxia, nutrient deprivation, proteasome dysfunction, sustained demands on the secretory pathway or somatic mutations in its client proteins--conditions often encountered by cancer cells-can lead to the accumulation of misfolded proteins in the ER and cause "ER stress...
November 16, 2016: American Journal of Physiology. Cell Physiology
Emily C Lumley, Acadia R Osborn, Jessica E Scott, Amanda G Scholl, Vicki Mercado, Young T McMahan, Zachary G Coffman, Jay L Brewster
The endoplasmic reticulum (ER) has the ability to signal organelle dysfunction via a complex signaling network known as the unfolded protein response (UPR). In this work, hamster fibroblast cells exhibiting moderate levels of ER stress were compared to those exhibiting severe ER stress. Inhibition of N-linked glycosylation was accomplished via a temperature-sensitive mutation in the Dad1 subunit of the oligosaccharyltransferase (OST) complex or by direct inhibition with tunicamycin (Tm). Temperature shift (TS) treatment generated weak activation of ER stress signaling when compared to doses of Tm that are typically used in ER stress studies (500-1000 nM)...
October 20, 2016: Cell Stress & Chaperones
Zhe Meng, Cristina Ruberti, Zhizhong Gong, Federica Brandizzi
Completion of a plant's life cycle depends on successful prioritization of signaling favoring either growth or defense. Although hormones are pivotal regulators of growth-defense tradeoffs, the underlying signaling mechanisms remain obscure. The unfolded protein response (UPR) is essential for physiological growth as well as endoplasmic reticulum (ER)-stress management in unfavorable growth conditions. The plant UPR transducers are the kinase and ribonuclease IRE1 and the transcription factors bZIP28 and bZIP60...
October 16, 2016: Plant Journal: for Cell and Molecular Biology
Soshi Kanemoto, Ryota Nitani, Tatsuhiko Murakami, Masayuki Kaneko, Rie Asada, Koji Matsuhisa, Atsushi Saito, Kazunori Imaizumi
The endoplasmic reticulum (ER) plays a pivotal role in maintaining cellular homeostasis. However, numerous environmental and genetic factors give rise to ER stress by inducing an accumulation of unfolded proteins. Under ER stress conditions, cells initiate the unfolded protein response (UPR). Here, we demonstrate a novel aspect of the UPR by electron microscopy and immunostaining analyses, whereby multivesicular body (MVB) formation was enhanced after ER stress. This MVB formation was influenced by inhibition of ER stress transducers inositol required enzyme 1 (IRE1) and PKR-like ER kinase (PERK)...
October 7, 2016: Biochemical and Biophysical Research Communications
Junnan Liu, Maolin Xiao, Jianjun Li, Delin Wang, Yunfeng He, Jiang He, Fei Gao, Li Mai, Ying Li, Yong Liang, Yuejiang Liu, Xiaoni Zhong
BACKGROUND: Currently, the role of UPR signaling in prostate cancer (PCa) is unclear. To evaluate the relationship between UPR signaling pathway and the prognosis of PCa, we explored the expression of IRE1, PERK, and ATF6 in tissues. METHODS: A total of 160 PCa and 30 benign prostate hyperplasia (BPH) tissues were collected. The expression of UPR signaling factors was assessed by immunohistochemistry. The staining characteristics were identified and evaluated for associations with clinicopathologic parameters, PSA recurrence survival, and prostate cancer-specific morality...
October 8, 2016: Prostate
Jianqiong Yang, Haiqing Liu, Linfu Li, Hai Liu, Weimei Shi, Xiaoliang Yuan, Longhuo Wu
IRE1 signaling is the most evolutionarily conserved branch in the UPR. IRE1 is an ER stress sensor and provides a structure-based platform for the unfolded proteins docking, which causes the luminal domain conformational change and oligomerization. This self-association of IRE1 facilitates the phosphorylation of activation loop, which unlocks the auto-inhibition in the kinase domain. The activating mechanistic cascade is thus initiated to induce DFG-in conformational change and movement of αC-helix to the active site...
September 27, 2016: Current Medicinal Chemistry
José Carlos Páez-Franco, Ignacio González-Sánchez, Nora A Gutiérrez-Nájera, Lilián G Valencia-Turcotte, Alfonso Lira-Rocha, Marco A Cerbón, Rogelio Rodríguez-Sotres
9-[(3-chloro)phenylamine]-2-[3-(diethylamine)propylamine]thiazolo[5,4-b]quinolone (D3ClP) is a bioisostere of N-(4-(acridin-9-ylamino)-3-methoxyphenyl)methanesulfonamide (m-AMSA) a DNA topoisomerase II inhibitor with proven cytotoxic activity and known to induce DNA damage and apoptotic cell death in K562 cells. However, recent evidence is not consistent with DNA topoisomerase II (DNA TOP2) as the primary target of D3ClP, in contrast to m-AMSA. We provide evidence of histone γH2AX phosphorylation at Ser135 in HeLa cells treated with D3ClP, a marker of DNA double strand repair through Mre11-Rad50-Nbs1 (MRN) pathway...
September 29, 2016: Journal of Cellular Biochemistry
Hang Nguyen, Bruce D Uhal
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...
November 1, 2016: American Journal of Physiology. Lung Cellular and Molecular Physiology
Omar Paul Arias Gaguancela, Lizbeth Peña Zúñiga, Alexis Vela Arias, Dennis Halterman, Francisco Javier Flores, Ida Elisabeth Johansen, Aiming Wang, Yasuyuki Yamaji, Jeanmarie Verchot-Lubicz
The inositol requiring enzyme (IRE1) is an endoplasmic reticulum (ER) stress sensor. When activated, it splices the bZIP60 mRNA producing a truncated transcription factor that upregulates genes involved in the unfolded protein response (UPR). Bax inhibitor 1 (BI-1) is another ER stress sensor that regulates cell death in response to environmental assaults. The potyvirus 6K2 and potexvirus TGB3 proteins are known to reside in the ER, serving respectively as anchors for the viral replicase and movement protein complex...
August 31, 2016: Molecular Plant-microbe Interactions: MPMI
Madduma Hewage Susara Ruwan Kumara, Mei Jing Piao, Kyoung Ah Kang, Yea Seong Ryu, Jeong Eon Park, Kristina Shilnikova, Jin Oh Jo, Young Sun Mok, Jennifer H Shin, Yeonsoo Park, Seong Bong Kim, Suk Jae Yoo, Jin Won Hyun
Colorectal cancer is a common type of tumor among both men and women worldwide. Conventional remedies such as chemotherapies pose the risk of side‑effects, and in many cases cancer cells develop chemoresistance to these treatments. Non‑thermal gas plasma (NTGP) was recently identified as a potential tool for cancer treatment. In this study, we investigated the potential use of NTGP to control SNUC5 human colon carcinoma cells. We hypothesized that NTGP would generate reactive oxygen species (ROS) in these cells, resulting in induction of endoplasmic reticulum (ER) stress...
October 2016: Oncology Reports
Allison Sumis, Katherine L Cook, Fabia O Andrade, Rong Hu, Emma Kidney, Xiyuan Zhang, Dominic Kim, Elissa Carney, Nguyen Nguyen, Wei Yu, Kerrie B Bouker, Idalia Cruz, Robert Clarke, Leena Hilakivi-Clarke
Social isolation is a strong predictor of early all-cause mortality and consistently increases breast cancer risk in both women and animal models. Because social isolation increases body weight, we compared its effects to those caused by a consumption of obesity-inducing diet (OID) in C57BL/6 mice. Social isolation and OID impaired insulin and glucose sensitivity. In socially isolated, OID-fed mice (I-OID), insulin resistance was linked to reduced Pparg expression and increased neuropeptide Y levels, but in group-housed OID fed mice (G-OID), it was linked to increased leptin and reduced adiponectin levels, indicating that the pathways leading to insulin resistance are different...
October 2016: Endocrine-related Cancer
Lindsey Devisscher, Margherita Vieri, Susan E Logue, Jens Panse, Anja Geerts, Hans van Vlierberghe, Eric Chevet, Adrienne M Gorman, Afshin Samali, Behzad Kharabi Masouleh
The VEGF family of pro-angiogenic factors has represented a pillar for targeted cancer therapy for more than a decade. In comparison, the field of protein homeostasis (proteostasis) focusing on the unfolded protein response (UPR), an endoplasmic reticulum (ER) stress-induced signaling cascade, has just recently emerged as an attractive anti-cancer approach. Recent findings suggest that both signaling pathways are incontestably interrelated to ensure cell survival. Herein, we summarize recent findings that demonstrate how these two fundamental aspects of cancer cell survival intersect and provide genetic and pharmacological evidence of the interplay between angiogenic factors such as VEGF-A or PlGF and the individual members of the UPR such as IRE1, PERK and ATF6...
July 21, 2016: Pharmacology & Therapeutics
E Cabrera, S Hernández-Pérez, S Koundrioukoff, M Debatisse, D Kim, M B Smolka, R Freire, D A Gillespie
Stresses such as hypoxia, nutrient deprivation and acidification disturb protein folding in the endoplasmic reticulum (ER) and activate the Unfolded Protein Response (UPR) to trigger adaptive responses through the effectors, PERK, IRE1 and ATF6. Most of these responses relate to ER homoeostasis; however, here we show that the PERK branch of the UPR also controls DNA replication. Treatment of cells with the non-genotoxic UPR agonist thapsigargin led to a rapid inhibition of DNA synthesis that was attributable to a combination of DNA replication fork slowing and reduced replication origin firing...
July 4, 2016: Oncogene
Mariana X Byndloss, Arina Marijke Keestra-Gounder, Andreas J Bäumler, Renée M Tsolis
Although viruses have long been known to subvert the endoplasmic reticulum (ER) for their replication, recent work has shown that this strategy is also used by bacterial pathogens and parasites to promote their intracellular growth. The ensuing disruption of cellular processes triggers a condition known as ER stress, which activates the host cell's unfolded protein response (UPR) to restore homeostasis. Recent work has linked the UPR, in particular the arm of this response that depends on the ER-resident sensor IRE1, to innate immunity and inflammation...
July 2016: DNA and Cell Biology
Asaha Fujimoto, Kei Kawana, Ayumi Taguchi, Katsuyuki Adachi, Masakazu Sato, Hiroe Nakamura, Juri Ogishima, Mitsuyo Yoshida, Tomoko Inoue, Haruka Nishida, Kensuke Tomio, Aki Yamashita, Yoko Matsumoto, Takahide Arimoto, Osamu Wada-Hiraike, Katsutoshi Oda, Takeshi Nagamatsu, Yutaka Osuga, Tomoyuki Fujii
Although cancer stem cells (CSC) have been implicated in the development of resistance to anti-cancer therapy including chemotherapy, the mechanisms underlying chemo-resistance by CSC have not yet been elucidated. We herein isolated sphere-forming (cancer stem-like) cells from the cervical cancer cell line, SiHa, and examined the unfolded protein reaction (UPR) to chemotherapeutic-induced endoplasmic reticulum (ER) stress. We revealed that tunicamycin-induced ER stress-mediated apoptosis occurred in monolayer, but not sphere-forming cells...
June 17, 2016: Oncotarget
Yan Deng, Renu Srivastava, Teagen D Quilichini, Haili Dong, Yan Bao, Harry T Horner, Stephen H Howell
The unfolded protein response (UPR) is activated by various stresses during vegetative development in Arabidopsis, but is constitutively active in anthers of unstressed plants. To understand the role of the UPR during reproductive development, we analyzed a double mutant, ire1a ire1b. The double mutant knocks out the RNA-splicing arm of the UPR signaling pathway. It is fertile at room temperature but male sterile at modestly elevated temperature (ET). The conditional male sterility in the mutant is a sporophytic trait, and when the double mutant was grown at ET, defects appeared in the structure of the tapetum...
October 2016: Plant Journal: for Cell and Molecular Biology
Quynh Giang Le, Yuki Ishiwata-Kimata, Kenji Kohno, Yukio Kimata
Cellular exposure to cadmium is known to strongly induce the unfolded protein response (UPR), which suggests that the endoplasmic reticulum (ER) is preferentially damaged by cadmium. According to recent reports, the UPR is induced both dependent on and independently of accumulation of unfolded proteins in the ER. In order to understand the toxic mechanism of cadmium, here we investigated how cadmium exposure leads to Ire1 activation, which triggers the UPR, using yeast Saccharomyces cerevisiae as a model organism...
August 2016: FEMS Yeast Research
Xiao-Wei Gu, Jia-Qi Yan, Hai-Ting Dou, Jie Liu, Li Liu, Meng-Long Zhao, Xiao-Huan Liang, Zeng-Ming Yang
Unfolded or misfolded protein accumulation in the endoplasmic reticulum lumen leads to endoplasmic reticulum stress (ER stress). Although it is known that ER stress is crucial for mammalian reproduction, little is known about its physiological significance and underlying mechanism during decidualization. Here we show that Ire-Xbp1 signal transduction pathway of unfolded protein response (UPR) is activated in decidual cells. The process of decidualization is compromised by ER stress inhibitor tauroursodeoxycholic acid sodium (TUDCA) and Ire specific inhibitor STF-083010 both in vivo and in vitro...
October 15, 2016: Molecular and Cellular Endocrinology
Silvia Conti, Simonetta Petrungaro, Elettra Sara Marini, Silvia Masciarelli, Luana Tomaipitinca, Antonio Filippini, Claudia Giampietri, Elio Ziparo
Cellular-Flice-like inhibitory protein (c-FLIP) is an apoptosis modulator known to inhibit the extrinsic apoptotic pathway thus blocking Caspase-8 processing in the Death Inducing Signalling Complex (DISC). We previously demonstrated that c-FLIP localizes at the endoplasmic reticulum (ER) and that c-FLIP-deficient mouse embryonic fibroblasts (MEFs) display an enlarged ER morphology. In the present study, we have addressed the consequences of c-FLIP ablation in the ER stress response by investigating the effects of pharmacologically-induced ER stress in Wild Type (WT) and c-FLIP-/- MEFs...
September 2016: Cellular Signalling
Lingrui Zhang, Changwei Zhang, Aiming Wang
The unfolded protein response (UPR) is crucial to life by regulating the cellular response to the stress in the endoplasmic reticulum (ER) imposed by abiotic and biotic cues such as heat shock and viral infection. The inositol requiring enzyme 1 (IRE1) signaling pathway activated by the IRE1-mediated unconventional splicing of HAC1 in yeast, bZIP60 in plants and XBP1 in metazoans, is the most ancient branch of the UPR. In this study, we systematically examined yeast IRE1p-HAC1, plant IRE1A/IRE1B-bZIP60 and human hIRE1-XBP1 pairs...
2016: Scientific Reports
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