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ER-associated degradation

Shangyu Yu, Shinji Ito, Ikuo Wada, Nobuko Hosokawa
Protein folding in the cell is regulated by several quality-control mechanisms. Correct folding of glycoproteins in the endoplasmic reticulum (ER) is tightly monitored by the recognition of glycan signals by lectins in the ER-associated degradation (ERAD) pathway. In mammals, mannose trimming from N-glycans is crucial for disposal of misfolded glycoproteins. The mannosidases responsible for this process are ER mannosidase I and ER degradation-enhancing α-mannosidase-like proteins (EDEMs). However, the molecular mechanism of mannose removal by EDEMs remains unclear, partly owing to the difficulty of reconstituting mannosidase activity in vitro Here, our analysis of EDEM3-mediated mannose-trimming activity on a misfolded glycoprotein revealed that ERp46, an ER-resident oxidoreductase, associates stably with EDEM3...
May 21, 2018: Journal of Biological Chemistry
Diane M Ward, Opal S Chen, Liangtao Li, Jerry Kaplan, Shah Alam Bhuiyan, Selvamuthu K Natarajan, Martin Bard, James E Cox
Ergosterol synthesis is essential for cellular growth and viability of the budding yeast Saccharomyces cerevisiae, and intracellular sterol distribution and homeostasis are therefore highly regulated in this species. Erg25 is an iron-containing C4-methyl sterol oxidase that contributes to the conversion of 4,4-dimethylzymosterol to zymosterol, a precursor of ergosterol. The ERG29 gene encodes an endoplasmic reticulum (ER)-associated protein, and here we identified a role for Erg29 in the methyl sterol oxidase step of ergosterol synthesis...
May 17, 2018: Journal of Biological Chemistry
Elena Gennadyevna Varlamova
The functions performed by the ER are diverse: synthesis of steroid hormones, synthesis of proteins for the plasma membrane, lysosomes, as well as proteins meant for exocytosis, protein folding, formation of disulfide bonds, N-linked glycosylation, etc. Selenoproteins localized in this organelle are definitely involved in the processes occurring in it, and the most common of them include participation in protein degradation, regulation of ER stress and redox metabolism. ER stress has been registered in many types of cancer cells...
July 2018: Journal of Trace Elements in Medicine and Biology
Jie-Mei Wang, Yining Qiu, Zhao Yang, Hyunbae Kim, Qingwen Qian, Qinghua Sun, Chunbin Zhang, Lei Yin, Deyu Fang, Sung Hong Back, Randal J Kaufman, Ling Yang, Kezhong Zhang
Obesity or a high-fat diet represses the endoribonuclease activity of inositol-requiring enzyme 1α (IRE1α), a transducer of the unfolded protein response (UPR) in cells under endoplasmic reticulum (ER) stress. An impaired UPR is associated with hepatic steatosis and nonalcoholic fatty liver disease (NAFLD), which is caused by lipid accumulation in the liver. We found that IRE1α was critical to maintaining lipid homeostasis in the liver by repressing the biogenesis of microRNAs (miRNAs) that regulate lipid mobilization...
May 15, 2018: Science Signaling
Rupert Abele, Robert Tampé
Living matter is defined by metastability, implying a tightly balanced synthesis and turnover of cellular components. The first step of eukaryotic protein degradation via the ubiquitin-proteasome system (UPS) leads to peptides, which are subsequently degraded to single amino acids by an armada of proteases. A small fraction of peptides, however, escapes further cytosolic destruction and is transported by ATP-binding cassette (ABC) transporters into the endoplasmic reticulum (ER) and lysosomes. The ER-resident heterodimeric transporter associated with antigen processing (TAP) is a crucial component in adaptive immunity for the transport and loading of peptides onto major histocompatibility complex class I (MHC I) molecules...
2018: Frontiers in Cell and Developmental Biology
Jingwen Liu, Yuhan Chen, Qingyang Huang, Wen Liu, Xiqing Ji, Fan Hu, Ying Zhu, Lingqiang Zhang, Guanglong Dong
The endoplasmic reticulum (ER) is a cellular organelle with central roles in maintaining proteostasis. The accumulation of misfolded proteins in the ER lumen causes ER stress. Cells evoke an evolutionarily conserved adaptive signaling network "unfolded protein response" to restore ER homeostasis, however, how the signaling network is delicately orchestrated remains largely unrevealed. Meanwhile, the HECT type E3 ligase Smad ubiquitylation regulatory factor 1 (Smurf1) has been reported to play critical roles in several important biological pathways by targeting distinct substrates for ubiquitylation, including WFS1, a critical mediator of ER stress, whereas the regulation of Smurf1 activity and abundance upon ER stress are poorly understood...
May 9, 2018: Cellular Signalling
Joanna Kopecka, Iris C Salaroglio, Luisella Righi, Roberta Libener, Sara Orecchia, Federica Grosso, Vladan Milosevic, Preeta Ananthanarayanan, Luisa Ricci, Enrica Capelletto, Monica Pradotto, Francesca Napoli, Massimo Di Maio, Silvia Novello, Menachem Rubinstein, Giorgio V Scagliotti, Chiara Riganti
OBJECTIVES: Cisplatin-based chemotherapy is moderately active in malignant pleural mesothelioma (MPM) due to intrinsic drug resistance and to low immunogenicity of MPM cells. CAAT/enhancer binding protein (C/EBP)-β LIP is a pro-apoptotic and chemosensitizing transcription factor activated in response to endoplasmic reticulum (ER) stress. MATERIALS AND METHODS: We investigated if LIP levels can predict the clinical response to cisplatin and survival of MPM patients receiving cisplatin-based chemotherapy...
June 2018: Lung Cancer: Journal of the International Association for the Study of Lung Cancer
L N Huiting, Y Samaha, G L Zhang, J E Roderick, B Li, N M Anderson, Y W Wang, L Wang, Fjf Laroche, J W Choi, C T Liu, M A Kelliher, H Feng
Despite the pivotal role of MYC in tumorigenesis, the mechanisms by which it promotes cancer aggressiveness remain incompletely understood. Here, we show that MYC transcriptionally upregulates the ubiquitin fusion degradation 1 (UFD1) gene in T-cell acute lymphoblastic leukemia (T-ALL). Allelic loss of ufd1 in zebrafish induces tumor cell apoptosis and impairs MYC-driven T-ALL progression but does not affect general health. As the E2 component of an endoplasmic reticulum (ER)-associated degradation (ERAD) complex, UFD1 facilitates the elimination of misfolded/unfolded proteins from the ER...
April 25, 2018: Leukemia: Official Journal of the Leukemia Society of America, Leukemia Research Fund, U.K
Hisae Kadowaki, Pasjan Satrimafitrah, Yasunari Takami, Hideki Nishitoh
The maintenance of endoplasmic reticulum (ER) homeostasis is essential for cell function. ER stress-induced pre-emptive quality control (ERpQC) helps alleviate the burden to a stressed ER by limiting further protein loading. We have previously reported the mechanisms of ERpQC, which includes a rerouting step and a degradation step. Under ER stress conditions, Derlin family proteins (Derlins), which are components of ER-associated degradation, reroute specific ER-targeting proteins to the cytosol. Newly synthesized rerouted polypeptides are degraded via the cytosolic chaperone Bag6 and the AAA-ATPase p97 in the ubiquitin-proteasome system...
May 9, 2018: Scientific Reports
Myoung Kyu Lee, Ye Ji Kim, Young-Eui Kim, Tae-Hee Han, Jens Milbradt, Manfred Marschall, Jin-Hyun Ahn
Interferon-stimulated gene (ISG) 15 encodes a ubiquitin-like protein that can be conjugated to proteins via an enzymatic cascade involving the E1, E2, and E3 enzymes. ISG15 expression and protein ISGylation modulate viral infection; however, the viral mechanisms regulating the function of ISG15 and ISGylation are not well understood. We recently showed that ISGylation suppresses the growth of human cytomegalovirus (HCMV) at multiple steps of the virus life cycle, and that the virus-encoded pUL26 protein inhibits protein ISGylation...
May 9, 2018: Journal of Virology
Le Zhang, Momei Zhou, Richard Stanton, Jeremy Kamil, Brent J Ryckman
Tropism of human cytomegalovirus (HCMV) is influenced by the envelope glycoprotein complexes gH/gL/gO and gH/gL/UL128-131. During virion assembly, gO and the UL128-131 proteins compete for binding to gH/gL in the ER. This assembly process clearly differs among strains since Merlin (ME) virions contain abundant gH/gL/UL128-131 and little gH/gL/gO, whereas TR contains much higher levels of total gH/gL, mostly in the form of gH/gL/gO, but much less gH/gL/UL128-131 than ME. Remaining questions include 1) what are the mechanisms behind these assembly differences, and 2) do differences reflect in vitro culture adaptations or natural genetic variations? Since the UL74(gO) ORF differs by 25% of amino acids between TR and ME, we analyzed recombinant viruses in which the UL74(gO) ORF was swapped...
May 9, 2018: Journal of Virology
Vicente Valenzuela, Kasey L Jackson, Sergio P Sardi, Claudio Hetz
Proteostasis alterations are proposed as a transversal hallmark of several pathological conditions, including metabolic disorders, mechanical injury, cardiac malfunction, neurodegeneration, and cancer. Strategies to improve proteostasis aim to reduce the accumulation of specific disease-related misfolded proteins or bolster the endogenous mechanisms to fold and degrade abnormal proteins. Endoplasmic reticulum (ER) stress is a common pathological signature of a variety of diseases, which engages the unfolded protein response (UPR) as a cellular reaction to mitigate ER stress...
April 7, 2018: Molecular Therapy: the Journal of the American Society of Gene Therapy
L Montibeller, J de Belleroche
The endoplasmic reticulum (ER) plays an important role in maintenance of proteostasis through the unfolded protein response (UPR), which is strongly activated in most neurodegenerative disorders. UPR signalling pathways mediated by IRE1α and ATF6 play a crucial role in the maintenance of ER homeostasis through the transactivation of an array of transcription factors. When activated, these transcription factors induce the expression of genes involved in protein folding and degradation with pro-survival effects...
May 4, 2018: Cell Stress & Chaperones
Diana Macedo, Carolina Jardim, Inês Figueira, A Filipa Almeida, Gordon J McDougall, Derek Stewart, Jose E Yuste, Francisco A Tomás-Barberán, Sandra Tenreiro, Tiago F Outeiro, Cláudia N Santos
Parkinson's disease (PD) is an age-related neurodegenerative disease associated with the misfolding and aggregation of alpha-synuclein (aSyn). The molecular underpinnings of PD are still obscure, but nutrition may play an important role in the prevention, onset, and disease progression. Dietary (poly)phenols revert and prevent age-related cognitive decline and neurodegeneration in model systems. However, only limited attempts were made to evaluate the impact of digestion on the bioactivities of (poly)phenols and determine their mechanisms of action...
May 3, 2018: Scientific Reports
Jieyeqi Yang, Wenying Chen, Boyang Zhang, Fengli Tian, Zheng Zhou, Xin Liao, Chen Li, Yi Zhang, Yanyan Han, Yan Wang, Yuzhe Li, Guo-Qing Wang, Xiao Li Shen
As a vital member of AAA+ (ATPase associated with diverse cellular activities) protein superfamily, Lon, a homo-hexameric ring-shaped protein complex with a serine-lysine catalytic dyad, is highly conserved throughout almost all prokaryotic and eukaryotic organisms. Lon protease (LONP) plays an important role in maintaining mitoproteostasis through selectively recognizing and degrading oxidatively modified mitoproteins within mitochondrial matrix, such as oxidized aconitase, phosphorylated mitochondrial transcription factor A, etc...
May 2, 2018: Archives of Toxicology
Xudong Wu, Tom A Rapoport
Misfolded proteins of the endoplasmic reticulum (ER) are discarded by a conserved process, called ER-associated protein degradation (ERAD). ERAD substrates are retro-translocated into the cytosol, polyubiquitinated, extracted from the ER membrane, and ultimately degraded by the proteasome. Recent in vitro experiments with purified components have given insight into the mechanism of ERAD. ERAD substrates with misfolded luminal or intramembrane domains are moved across the ER membrane through a channel formed by the multispanning ubiquitin ligase Hrd1...
April 29, 2018: Current Opinion in Cell Biology
Deniz Kuscuoglu, Sabina Janciauskiene, Karim Hamesch, Johannes Haybaeck, Christian Trautwein, Pavel Strnad
In the endoplasmic reticulum (ER), hepatocytes synthesize the majority of serum proteins and this production is adjusted by complex local and systemic regulatory mechanisms. Accordingly, serum levels of hepatocyte-made proteins constitute important biomarkers that reflect both systemic processes and the status of the liver. For example, C-reactive protein is an established marker of inflammatory reaction, whereas transferrin emerges as a liver stress marker and an attractive mortality predictor. The high protein flow through the ER poses a continuous challenge that is handled by a complex proteostatic network consisting of ER folding machinery, ER stress response, ER-associated degradation and autophagy...
April 27, 2018: Journal of Hepatology
Xin Lin, Xingting Liu, Yanfen Ma, Yuling Mi, Weidong Zeng, Jian Li, Caiqiao Zhang
After ovulation in mammals, rupture of mature follicles is reorganized into the corpus luteum that secrets progesterone (P4 ) to stimulate endometrial development. The situation in birds differs considerably. Beyond ovulation the ruptured avian follicle forms a postovulatory follicle (POF) that is not considered analogous to mammalian corpus luteum. The function and regression mechanisms of avian POFs remain poorly understood. Here we investigated the changes in apoptotic and autophagic activities that were involved during POF degradation...
April 29, 2018: Aging
Annemieke T van der Goot, Margaret M P Pearce, Dara E Leto, Thomas A Shaler, Ron R Kopito
Glycoproteins engaged in unproductive folding in the ER are marked for degradation by a signal generated by progressive demannosylation of substrate N-glycans that is decoded by ER lectins, but how the two lectins, OS9 and XTP3B, contribute to non-glycosylated protein triage is unknown. We generated cell lines with homozygous deletions of both lectins individually and in combination. We found that OS9 and XTP3B redundantly promote glycoprotein degradation and stabilize the SEL1L/HRD1 dislocon complex, that XTP3B profoundly inhibits the degradation of non-glycosylated proteins, and that OS9 antagonizes this inhibition...
April 12, 2018: Molecular Cell
Yiman Li, Yajun Xie, Jin Hao, Jianing Liu, Yating Ning, Qi Tang, Meng Ma, Hang Zhou, Shengdong Guan, Qin Zhou, Xiaoyan Lv
ER-localized proteins have been reported function in endoplasmic reticulum, unfolded protein degradation and destruction of misfolded proteins by the ER-associated protein degradation (ERAD) system, but their function in the chemotaxis of macrophage cells remained un-addressed. Here, we showed that ER protein with ubiquitin like domain 1(Herpud1) was upregulated in IL-4-treated M2 macrophage cells and its expression pattern was similar with macrophage polarization markers, such as Arg1, Mrc1 and Fizz1. Inhibition of Herpud1 by using specific target shRNA decreased these marker's expression at mRNA and protein level in IL-4-treated or -untreated M2 macrophage cells...
April 24, 2018: Experimental Cell Research
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