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molecular chaperone and endoplasmic reticulum

Fiorenza Fumagalli, Julia Noack, Timothy J Bergmann, Eduardo Cebollero Presmanes, Giorgia Brambilla Pisoni, Elisa Fasana, Ilaria Fregno, Carmela Galli, Marisa Loi, Tatiana Soldà, Rocco D'Antuono, Andrea Raimondi, Martin Jung, Armin Melnyk, Stefan Schorr, Anne Schreiber, Luca Simonelli, Luca Varani, Caroline Wilson-Zbinden, Oliver Zerbe, Kay Hofmann, Matthias Peter, Manfredo Quadroni, Richard Zimmermann, Maurizio Molinari
The endoplasmic reticulum (ER) is a site of protein biogenesis in eukaryotic cells. Perturbing ER homeostasis activates stress programs collectively called the unfolded protein response (UPR). The UPR enhances production of ER-resident chaperones and enzymes to reduce the burden of misfolded proteins. On resolution of ER stress, ill-defined, selective autophagic programs remove excess ER components. Here we identify Sec62, a constituent of the translocon complex regulating protein import in the mammalian ER, as an ER-resident autophagy receptor...
October 17, 2016: Nature Cell Biology
John J Chen, Joseph C Genereux, Eul Hyun Suh, Vincent F Vartabedian, Bibiana Rius, Song Qu, Maria T A Dendle, Jeffery W Kelly, R Luke Wiseman
Transthyretin (TTR) is a tetrameric serum protein associated with multiple systemic amyloid diseases. In these disorders, TTR aggregates in extracellular environments through a mechanism involving rate-limiting dissociation of the tetramer to monomers, which then misfold and aggregate into soluble oligomers and amyloid fibrils that induce toxicity in distal tissues. Using an assay established herein, we show that highly destabilized, aggregation-prone TTR variants are secreted as both native tetramers and non-native conformations that accumulate as high-molecular-weight oligomers...
October 20, 2016: Cell Chemical Biology
Genevieve Beauvais, Nicole M Bode, Jaime L Watson, Hsiang Wen, Kevin A Glenn, Hiroyuki Kawano, N Charles Harata, Michelle E Ehrlich, Pedro Gonzalez-Alegre
: Dystonia type 1 (DYT1) is a dominantly inherited neurological disease caused by mutations in TOR1A, the gene encoding the endoplasmic reticulum (ER)-resident protein torsinA. Previous work mostly completed in cell-based systems suggests that mutant torsinA alters protein processing in the secretory pathway. We hypothesized that inducing ER stress in the mammalian brain in vivo would trigger or exacerbate mutant torsinA-induced dysfunction. To test this hypothesis, we crossed DYT1 knock-in with p58(IPK)-null mice...
October 5, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Ryo Ushioda, Akitoshi Miyamoto, Michio Inoue, Satoshi Watanabe, Masaki Okumura, Ken-Ichi Maegawa, Kaiku Uegaki, Shohei Fujii, Yasuko Fukuda, Masataka Umitsu, Junichi Takagi, Kenji Inaba, Katsuhiko Mikoshiba, Kazuhiro Nagata
Calcium ion (Ca(2+)) is an important second messenger that regulates numerous cellular functions. Intracellular Ca(2+) concentration ([Ca(2+)]i) is strictly controlled by Ca(2+) channels and pumps on the endoplasmic reticulum (ER) and plasma membranes. The ER calcium pump, sarco/endoplasmic reticulum calcium ATPase (SERCA), imports Ca(2+) from the cytosol into the ER in an ATPase activity-dependent manner. The activity of SERCA2b, the ubiquitous isoform of SERCA, is negatively regulated by disulfide bond formation between two luminal cysteines...
October 11, 2016: Proceedings of the National Academy of Sciences of the United States of America
C Fu, H Zhao, Y Wang, H Cai, Y Xiao, Y Zeng, H Chen
Glycosylation is one of the major posttranslational modifications of proteins. N-glycosylation (Asn-linked) and O-glycosylation (Ser/Thr-linked) are the two main forms. Abnormal O-glycosylation is frequently observed on the surface of tumor cells, and is associated with an adverse outcome and poor prognosis in patients with cancer. O-glycans (Tn, sTn, and T antigen) can be synthesized in the Golgi apparatus with the aid of several glycosyltransferases (such as T-synthase and ST6GalNAc-I) in a suitable environment...
September 28, 2016: HLA
Shanshan Liu, Timothy O Street
The molecular chaperone Hsp90 facilitates the folding and modulates activation of diverse substrate proteins. Unlike other heat shock proteins such as Hsp60 and Hsp70, Hsp90 plays critical regulatory roles by maintaining active states of kinases, many of which are overactive in cancer cells. Four Hsp90 paralogs are expressed in eukaryotic cells: Hsp90α/β (in the cytosol), Grp94 (in the endoplasmic reticulum), Trap1 (in mitochondria). Although numerous Hsp90 inhibitors are being tested in cancer clinical trials, little is known about why different Hsp90 inhibitors show specificity among Hsp90 paralogs...
September 26, 2016: Protein Science: a Publication of the Protein Society
Sara Ortega-Atienza, Blazej Rubis, Caitlin McCarthy, Anatoly Zhitkovich
Endogenous and exogenous formaldehyde (FA) has been linked to cancer, neurotoxicity, and other pathophysiologic effects. Molecular and cellular mechanisms that underlie FA-induced damage are poorly understood. In this study, we investigated whether proteotoxicity is an important, unrecognized factor in cell injury caused by FA. We found that irrespective of their cell cycle phases, all FA-treated human cells rapidly accumulated large amounts of proteins with proteasome-targeting K48-linked polyubiquitin, which was comparable with levels of polyubiquitination in proteasome-inhibited MG132 controls...
September 14, 2016: American Journal of Pathology
Parijat Kabiraj, Jose Eduardo Marin, Armando Varela-Ramirez, Mahesh Narayan
Amyloid beta (Aβ) aggregation is generally associated with Alzheimer's onset. Here, we demonstrate that incubation of dopaminergic SH-SY5Y cells with an Aβ peptide fragment (an 11-mer composed of residues 25-35; Aβ (25-35)) results in elevated intracellular nitrosative stress and induces chemical mutation of protein disulfide isomerase (PDI), an endoplasmic reticulum-resident oxidoreductase chaperone. Furthermore, Aβ (25-35) provokes aggregation of both the minor and major biomarkers of Parkinson's disease, namely, synphilin-1 and α-synuclein, respectively...
October 3, 2016: ACS Chemical Neuroscience
Xuan Zhou, Xiaoming Xing, Shuping Zhang, Lili Liu, Chengqin Wang, Lin Li, Qiuxia Ji, Huamin Liu
Glucose-regulated protein 78 (GRP78), a molecular chaperon in the endoplasmic reticulum (ER), is overexpressed in a variety of tumor types and plays a critical role in cancer cell proliferation, migration, invasion and drug resistance. However, the mechanisms underlying the role of GRP78 in tumor carcinogenesis remain largely unknown. In the present study, we found that GRP78 knockdown in colorectal carcinoma (CRC) cells significantly inhibited cell proliferation, colony formation and tumorigenesis in vitro and in vivo...
September 16, 2016: Oncology Reports
Kwang-Woo Jung, Yee-Seul So, Yong-Sun Bahn
Cryptococcus neoformans, a global fungal meningitis pathogen, employs the unfolded protein response pathway. This pathway, which consists of an evolutionarily conserved Ire1 kinase/endoribonuclease and a unique transcription factor (Hxl1), modulates the endoplasmic reticulum stress response and pathogenicity. Here, we report that the unfolded protein response pathway governs sexual and unisexual differentiation of C. neoformans in an Ire1-dependent but Hxl1-independent manner. The ire1∆ mutants showed defects in sexual mating, with reduced cell fusion and pheromone-mediated formation of the conjugation tube...
2016: Scientific Reports
Huanxian Chen, Linmin Chen, Liang Wang, Xinhua Zhou, Judy Yuet-Wa Chan, Jingjing Li, Guozhen Cui, Simon Ming-Yuen Lee
Curcumin and fenretinide are 2 well-known and promising chemotherapeutic compounds via various molecular mechanisms. However, the anticancer capacity of either curcumin or fenretinide is limited. This prompted us to examine the combined anticancer effects of curcumin and fenretinide. Our results demonstrate for the first time that there is synergistic anticancer effect of combined treatment with these 2 agents, leading to enhanced cytotoxicity and enhanced expression level of pro-apoptotic protein cleaved PARP in non-small cell lung cancer (NSCLC) cells while showed little toxicity to rat cardiomyoblast normal cells...
August 11, 2016: Cancer Biology & Therapy
Paula Abello-Cáceres, Javier Pizarro-Bauerle, Carlos Rosas, Ismael Maldonado, Lorena Aguilar-Guzmán, Carlos González, Galia Ramírez, Jorge Ferreira, Arturo Ferreira
BACKGROUND: For several decades now an antagonism between Trypanosoma cruzi infection and tumor development has been detected. The molecular basis of this phenomenon remained basically unknown until our proposal that T. cruzi Calreticulin (TcCRT), an endoplasmic reticulum-resident chaperone, translocated-externalized by the parasite, may mediate at least an important part of this effect. Thus, recombinant TcCRT (rTcCRT) has important in vivo antiangiogenic and antitumor activities. However, the relevant question whether the in vivo antitumor effect of T...
2016: BMC Cancer
Yan Fan, Johnny J He
HIV-1 Tat is a major culprit for HIV/neuroAIDS. One of the consistent hallmarks of HIV/neuroAIDS is reactive astrocytes or astrocytosis, characterized by increased cytoplasmic accumulation of the intermediate filament glial fibrillary acidic protein (GFAP). We have shown that that Tat induces GFAP expression in astrocytes and that GFAP activation is indispensible for astrocyte-mediated Tat neurotoxicity. However, the underlying molecular mechanisms are not known. In this study, we showed that Tat expression or GFAP expression led to formation of GFAP aggregates and induction of unfold protein response (UPR) and endoplasmic reticulum (ER) stress in astrocytes...
September 8, 2016: Journal of Biological Chemistry
Daniel N Hebert, Eugenia M Clerico, Lila M Gierasch
In this issue of Molecular Cell, Behnke et al. (2016) describe a novel cell-based peptide-binding assay and use it to analyze the binding specificities of the endoplasmic reticulum Hsp70 chaperone and its co-chaperones and to probe their different roles in protein quality control.
September 1, 2016: Molecular Cell
Natalia J Martinez, Ganesha Rai, Adam Yasgar, Wendy A Lea, Hongmao Sun, Yuhong Wang, Diane K Luci, Shyh-Ming Yang, Kana Nishihara, Shunichi Takeda, Mohiuddin Sagor, Irina Earnshaw, Tetsuya Okada, Kazutoshi Mori, Kelli Wilson, Gregory J Riggins, Menghang Xia, Maurizio Grimaldi, Ajit Jadhav, David J Maloney, Anton Simeonov
The endoplasmic reticulum (ER) is involved in Ca2+ signaling and protein folding. ER Ca2+ depletion and accumulation of unfolded proteins activate the molecular chaperone GRP78 (glucose-regulated protein 78) which in turn triggers the ER stress response (ERSR) pathway aimed to restore ER homeostasis. Failure to adapt to stress, however, results in apoptosis. We and others have shown that malignant cells are more susceptible to ERSR-induced apoptosis than their normal counterparts, implicating the ERSR as a potential target for cancer therapeutics...
2016: PloS One
J S J Tan, K C Ong Kc, A Rhodes
Heat shock proteins (HSPs) are a family of evolutionary conserved proteins that work as molecular chaperones for cellular proteins essential for cell viability and growth as well as having numerous cyto-protective roles. They are sub-categorised based on their molecular weights; amongst which some of the most extensively studied are the HSP90 and HSP70 families. Important members of these two families; Heat shock proteins 70 and heat shock proteins 90 (Hsp70/90), are the glucose regulated proteins (GRP). These stress-inducible chaperones possess distinct roles from that of the other HSPs, residing mostly in the endoplasmic reticulum and mitochondria, but they can also be translocated to other cellular locations...
August 2016: Malaysian Journal of Pathology
Gurdeep Marwarha, Kate Claycombe, Jared Schommer, David Collins, Othman Ghribi
The peptide hormones Insulin-like growth factor-1 (IGF1) and leptin mediate a myriad of biological effects - both in the peripheral and central nervous systems. The transcription of these two hormones is regulated by the transcription factor C/EBPα, which in turn is negatively regulated by the transcription factor C/EBP Homologous Protein (CHOP), a specific marker of endoplasmic reticulum (ER) stress. In the peripheral system, disturbances in leptin and IGF-1 levels are implicated in a variety of metabolic diseases including obesity, diabetes, atherosclerosis and cardiovascular diseases...
November 2016: Cellular Signalling
Alvaro Sanchez-Martinez, Michelle Beavan, Matthew E Gegg, Kai-Yin Chau, Alexander J Whitworth, Anthony H V Schapira
GBA gene mutations are the greatest cause of Parkinson disease (PD). GBA encodes the lysosomal enzyme glucocerebrosidase (GCase) but the mechanisms by which loss of GCase contributes to PD remain unclear. Inhibition of autophagy and the generation of endoplasmic reticulum (ER) stress are both implicated. Mutant GCase can unfold in the ER and be degraded via the unfolded protein response, activating ER stress and reducing lysosomal GCase. Small molecule chaperones that cross the blood brain barrier help mutant GCase refold and traffic correctly to lysosomes are putative treatments for PD...
2016: Scientific Reports
Michael J Williams, Emelie Perland, Mikaela M Eriksson, Josef Carlsson, Daniel Erlandsson, Loora Laan, Tabusi Mahebali, Ella Potter, Robert Frediksson, Christian Benedict, Helgi B Schiöth
Lack of quality sleep increases central nervous system oxidative stress and impairs removal of neurotoxic soluble metabolites from brain parenchyma. During aging poor sleep quality, caused by sleep fragmentation, increases central nervous system cellular stress. Currently, it is not known how organisms offset age-related cytotoxic metabolite increases in order to safeguard neuronal survival. Furthermore, it is not understood how age and sleep fragmentation interact to affect oxidative stress protection pathways...
2016: Frontiers in Aging Neuroscience
Babak Nami, Armin Ghasemi-Dizgah, Akbar Vaseghi
INTRODUCTION: Breast cancer stem cell with CD44(hi)/CD24(lo) phonotype is described having stem cell properties and represented as the main driving factor in breast cancer initiation, growth, metastasis and low response to anti-cancer agents. Glucoseregulated proteins (GRPs) are heat shock protein family chaperons that are charged with regulation of protein machinery and modulation of endoplasmic reticulum homeostasis whose important roles in stem cell development and invasion of various cancers have been demonstrated...
2016: BioImpacts: BI
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