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Malvezzi AM, Aricó M, Souza-Melo N, Dos Santos GP, Bittencourt-Cunha P, Holetz FB, Schenkman S. GCN2-Like Kinase Modulates Stress Granule Formation During Nutritional Stress in Trypanosoma cruzi. Front Cell Infect Microbiol 2020; 10:149. [PMID: 32373547 PMCID: PMC7176912 DOI: 10.3389/fcimb.2020.00149] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 03/20/2020] [Indexed: 12/24/2022] Open
Abstract
The integrated stress response in eukaryotic cells is an orchestrated pathway that leads to eukaryotic Initiation Factor 2 alpha subunit (eIF2α) phosphorylation at ser51 and ultimately activates pathways to mitigate cellular damages. Three putative kinases (Tck1, Tck2, and Tck3) are found in the Trypanosoma cruzi genome, the flagellated parasite that causes Chagas disease. These kinases present similarities to other eukaryotic eIF2α kinases, exhibiting a typical insertion loop in the kinase domain of the protein. We found that this insertion loop is conserved among kinase 1 of several T. cruzi strains but differs among various Kinetoplastidae species, suggesting unique roles. Kinase 1 is orthologous of GCN2 of several eukaryotes, which have been implicated in the eIF2α ser51 phosphorylation in situations that mainly affects the nutrients levels. Therefore, we further investigated the responses to nutritional stress of T. cruzi devoid of TcK1 generated by CRISPR/Cas9 gene replacement. In nutrient-rich conditions, replicative T. cruzi epimastigotes depleted of TcK1 proliferate as wild type cells but showed increased levels of polysomes relative to monosomes. Upon nutritional deprivation, the polysomes decreased more than in TcK1 depleted line. However, eIF2α is still phosphorylated in TcK1 depleted line, as in wild type parasites. eIF2α phosphorylation increased at longer incubations times, but KO parasites showed less accumulation of ribonucleoprotein granules containing ATP-dependent RNA helicase involved in mRNA turnover (DHH1) and Poly-A binding protein (PABP1). Additionally, the formation of metacyclic-trypomastigotes is increased in the absence of Tck1 compared to controls. These metacyclics, as well as tissue culture trypomastigotes derived from the TcK1 knockout line, were less infective to mammalian host cells, although replicated faster inside mammalian cells. These results indicate that GCN2-like kinase in T. cruzi affects stress granule formation, independently of eIF2α phosphorylation upon nutrient deprivation. It also modulates the fate of the parasites during differentiation, invasion, and intracellular proliferation.
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Affiliation(s)
- Amaranta Muniz Malvezzi
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Mirella Aricó
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Normanda Souza-Melo
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Gregory Pedroso Dos Santos
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Paula Bittencourt-Cunha
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | | | - Sergio Schenkman
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
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102
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Salminen A, Kaarniranta K, Kauppinen A. ER stress activates immunosuppressive network: implications for aging and Alzheimer's disease. J Mol Med (Berl) 2020; 98:633-650. [PMID: 32279085 PMCID: PMC7220864 DOI: 10.1007/s00109-020-01904-z] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 03/24/2020] [Accepted: 03/26/2020] [Indexed: 12/14/2022]
Abstract
The endoplasmic reticulum (ER) contains stress sensors which recognize the accumulation of unfolded proteins within the lumen of ER, and subsequently these transducers stimulate the unfolded protein response (UPR). The ER sensors include the IRE1, PERK, and ATF6 transducers which activate the UPR in an attempt to restore the quality of protein folding and thus maintain cellular homeostasis. If there is excessive stress, UPR signaling generates alarmins, e.g., chemokines and cytokines, which activate not only tissue-resident immune cells but also recruit myeloid and lymphoid cells into the affected tissues. ER stress is a crucial inducer of inflammation in many pathological conditions. A chronic low-grade inflammation and cellular senescence have been associated with the aging process and many age-related diseases, such as Alzheimer’s disease. Currently, it is known that immune cells can exhibit great plasticity, i.e., they are able to display both pro-inflammatory and anti-inflammatory phenotypes in a context-dependent manner. The microenvironment encountered in chronic inflammatory conditions triggers a compensatory immunosuppression which defends tissues from excessive inflammation. Recent studies have revealed that chronic ER stress augments the suppressive phenotypes of immune cells, e.g., in tumors and other inflammatory disorders. The activation of immunosuppressive network, including myeloid-derived suppressor cells (MDSC) and regulatory T cells (Treg), has been involved in the aging process and Alzheimer’s disease. We will examine in detail whether the ER stress-related changes found in aging tissues and Alzheimer’s disease are associated with the activation of immunosuppressive network, as has been observed in tumors and many chronic inflammatory diseases.
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Affiliation(s)
- Antero Salminen
- Department of Neurology, Institute of Clinical Medicine, University of Eastern Finland, P.O. Box 1627, FI-70211, Kuopio, Finland.
| | - Kai Kaarniranta
- Department of Ophthalmology, Institute of Clinical Medicine, University of Eastern Finland, P.O. Box 1627, FI-70211, Kuopio, Finland.,Department of Ophthalmology, Kuopio University Hospital, P.O. Box 100, FI-70029, Kuopio, Finland
| | - Anu Kauppinen
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, P.O. Box 1627, FI-70211, Kuopio, Finland
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103
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Aminoacyl-tRNA synthetase inhibition activates a pathway that branches from the canonical amino acid response in mammalian cells. Proc Natl Acad Sci U S A 2020; 117:8900-8911. [PMID: 32253314 DOI: 10.1073/pnas.1913788117] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Signaling pathways that sense amino acid abundance are integral to tissue homeostasis and cellular defense. Our laboratory has previously shown that halofuginone (HF) inhibits the prolyl-tRNA synthetase catalytic activity of glutamyl-prolyl-tRNA synthetase (EPRS), thereby activating the amino acid response (AAR). We now show that HF treatment selectively inhibits inflammatory responses in diverse cell types and that these therapeutic benefits occur in cells that lack GCN2, the signature effector of the AAR. Depletion of arginine, histidine, or lysine from cultured fibroblast-like synoviocytes recapitulates key aspects of HF treatment, without utilizing GCN2 or mammalian target of rapamycin complex 1 pathway signaling. Like HF, the threonyl-tRNA synthetase inhibitor borrelidin suppresses the induction of tissue remodeling and inflammatory mediators in cytokine-stimulated fibroblast-like synoviocytes without GCN2, but both aminoacyl-tRNA synthetase (aaRS) inhibitors are sensitive to the removal of GCN1. GCN1, an upstream component of the AAR pathway, binds to ribosomes and is required for GCN2 activation. These observations indicate that aaRS inhibitors, like HF, can modulate inflammatory response without the AAR/GCN2 signaling cassette, and that GCN1 has a role that is distinct from its activation of GCN2. We propose that GCN1 participates in a previously unrecognized amino acid sensor pathway that branches from the canonical AAR.
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104
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Afrin T, Diwan D, Sahawneh K, Pajerowska-Mukhtar K. Multilevel regulation of endoplasmic reticulum stress responses in plants: where old roads and new paths meet. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:1659-1667. [PMID: 31679034 DOI: 10.1093/jxb/erz487] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 10/21/2019] [Indexed: 05/20/2023]
Abstract
The sessile lifestyle of plants requires them to cope with a multitude of stresses in situ. In response to diverse environmental and intracellular cues, plant cells respond by massive reprogramming of transcription and translation of stress response regulators, many of which rely on endoplasmic reticulum (ER) processing. This increased protein synthesis could exceed the capacity of precise protein quality control, leading to the accumulation of unfolded and/or misfolded proteins that triggers the unfolded protein response (UPR). Such cellular stress responses are multilayered and executed in different cellular compartments. Here, we will discuss the three main branches of UPR signaling in diverse eukaryotic systems, and describe various levels of ER stress response regulation that encompass transcriptional gene regulation by master transcription factors, post-transcriptional activities including cytoplasmic splicing, translational control, and multiple post-translational events such as peptide modifications and cleavage. In addition, we will discuss the roles of plant ER stress sensors in abiotic and biotic stress responses and speculate on the future prospects of engineering these signaling events for heightened stress tolerance.
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Affiliation(s)
- Taiaba Afrin
- Department of Biology, University of Alabama at Birmingham, Birmingham, USA
| | - Danish Diwan
- Department of Biology, University of Alabama at Birmingham, Birmingham, USA
| | - Katrina Sahawneh
- Department of Biology, University of Alabama at Birmingham, Birmingham, USA
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105
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Yeast as a Model to Understand Actin-Mediated Cellular Functions in Mammals-Illustrated with Four Actin Cytoskeleton Proteins. Cells 2020; 9:cells9030672. [PMID: 32164332 PMCID: PMC7140605 DOI: 10.3390/cells9030672] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 03/05/2020] [Accepted: 03/05/2020] [Indexed: 12/31/2022] Open
Abstract
The budding yeast Saccharomyces cerevisiae has an actin cytoskeleton that comprises a set of protein components analogous to those found in the actin cytoskeletons of higher eukaryotes. Furthermore, the actin cytoskeletons of S. cerevisiae and of higher eukaryotes have some similar physiological roles. The genetic tractability of budding yeast and the availability of a stable haploid cell type facilitates the application of molecular genetic approaches to assign functions to the various actin cytoskeleton components. This has provided information that is in general complementary to that provided by studies of the equivalent proteins of higher eukaryotes and hence has enabled a more complete view of the role of these proteins. Several human functional homologues of yeast actin effectors are implicated in diseases. A better understanding of the molecular mechanisms underpinning the functions of these proteins is critical to develop improved therapeutic strategies. In this article we chose as examples four evolutionarily conserved proteins that associate with the actin cytoskeleton: (1) yeast Hof1p/mammalian PSTPIP1, (2) yeast Rvs167p/mammalian BIN1, (3) yeast eEF1A/eEF1A1 and eEF1A2 and (4) yeast Yih1p/mammalian IMPACT. We compare the knowledge on the functions of these actin cytoskeleton-associated proteins that has arisen from studies of their homologues in yeast with information that has been obtained from in vivo studies using live animals or in vitro studies using cultured animal cell lines.
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106
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Simpson LJ, Tzima E, Reader JS. Mechanical Forces and Their Effect on the Ribosome and Protein Translation Machinery. Cells 2020; 9:cells9030650. [PMID: 32156009 PMCID: PMC7140433 DOI: 10.3390/cells9030650] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 03/03/2020] [Accepted: 03/04/2020] [Indexed: 12/12/2022] Open
Abstract
Mechanical forces acting on biological systems, at both the macroscopic and microscopic levels, play an important part in shaping cellular phenotypes. There is a growing realization that biomolecules that respond to force directly applied to them, or via mechano-sensitive signalling pathways, can produce profound changes to not only transcriptional pathways, but also in protein translation. Forces naturally occurring at the molecular level can impact the rate at which the bacterial ribosome translates messenger RNA (mRNA) transcripts and influence processes such as co-translational folding of a nascent protein as it exits the ribosome. In eukaryotes, force can also be transduced at the cellular level by the cytoskeleton, the cell’s internal filamentous network. The cytoskeleton closely associates with components of the translational machinery such as ribosomes and elongation factors and, as such, is a crucial determinant of localized protein translation. In this review we will give (1) a brief overview of protein translation in bacteria and eukaryotes and then discuss (2) how mechanical forces are directly involved with ribosomes during active protein synthesis and (3) how eukaryotic ribosomes and other protein translation machinery intimately associates with the mechanosensitive cytoskeleton network.
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107
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Towards a model of GCN2 activation. Biochem Soc Trans 2020; 47:1481-1488. [PMID: 31647517 PMCID: PMC6824675 DOI: 10.1042/bst20190331] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 09/19/2019] [Accepted: 09/23/2019] [Indexed: 01/06/2023]
Abstract
Cells must be able to sense and adapt to their surroundings to thrive in a dynamic environment. Key to adapting to a low nutrient environment is the Integrated Stress Response (ISR), a short-lived pathway that allows cells to either regain cellular homeostasis or facilitate apoptosis during periods of stress. Central to the ISR is the protein kinase General Control Non-depressible 2 (GCN2), which is responsible for sensing starvation. Upon amino acid deficiency, GCN2 is activated and initiates the ISR by phosphorylating the translation initiation factor eIF2α, stalling protein translation, and activating the transcription factor ATF4, which in turn up-regulates autophagy and biosynthesis pathways. A key outstanding question is how GCN2 is activated from an autoinhibited state. Until recently, a model of activation focussed on the increase of deacylated tRNA associated with amino acid starvation, with deacylated tRNA binding directly to GCN2 and releasing autoinhibition. However, in vivo experiments have pointed towards an alternative, deacylated-tRNA-independent mechanism of activation. Here, we review the various factors that may facilitate GCN2 activation, including recent research showing that the P-stalk complex, a ribosome-associated heteropentameric protein complex, is a potent activator of GCN2.
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108
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Patent highlights, August-September 2019. Pharm Pat Anal 2020; 9:9-16. [PMID: 32008423 DOI: 10.4155/ppa-2019-0023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A snapshot of recent noteworthy developments in the patent literature of relevance to pharmaceutical and medical research and development.
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109
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Romero AM, Ramos-Alonso L, Alepuz P, Puig S, Martínez-Pastor MT. Global translational repression induced by iron deficiency in yeast depends on the Gcn2/eIF2α pathway. Sci Rep 2020; 10:233. [PMID: 31937829 PMCID: PMC6959253 DOI: 10.1038/s41598-019-57132-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 12/16/2019] [Indexed: 11/09/2022] Open
Abstract
Iron is an essential element for all eukaryotic organisms because it participates as a redox active cofactor in a wide range of biological processes, including protein synthesis. Translation is probably the most energy consuming process in cells. Therefore, one of the initial responses of eukaryotic cells to stress or nutrient limitation is the arrest of mRNA translation. In first instance, the budding yeast Saccharomyces cerevisiae responds to iron deficiency by activating iron acquisition and remodeling cellular metabolism in order to prioritize essential over non-essential iron-dependent processes. We have determined that, despite a global decrease in transcription, mRNA translation is actively maintained during a short-term exposure to iron scarcity. However, a more severe iron deficiency condition induces a global repression of translation. Our results indicate that the Gcn2-eIF2α pathway limits general translation at its initiation step during iron deficiency. This bulk translational inhibition depends on the uncharged tRNA sensing Gcn1-Gcn20 complex. The involvement of the Gcn2-eIF2α pathway in the response to iron deficiency highlights its central role in the eukaryotic response to stress or nutritional deprivation, which is conserved from yeast to mammals.
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Affiliation(s)
- Antonia María Romero
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Catedrático Agustín Escardino 7, E-46980, Paterna, Valencia, Spain
| | - Lucía Ramos-Alonso
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Catedrático Agustín Escardino 7, E-46980, Paterna, Valencia, Spain
| | - Paula Alepuz
- Departamento de Bioquímica y Biología Molecular, Universitat de València, Doctor Moliner 50, E-46100, Burjassot, Valencia, Spain.,ERI Biotecmed, Universitat de València, Doctor Moliner 50, E-46100, Burjassot, Valencia, Spain
| | - Sergi Puig
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Catedrático Agustín Escardino 7, E-46980, Paterna, Valencia, Spain.
| | - María Teresa Martínez-Pastor
- Departamento de Bioquímica y Biología Molecular, Universitat de València, Doctor Moliner 50, E-46100, Burjassot, Valencia, Spain.
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110
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Nouwen LV, Everts B. Pathogens MenTORing Macrophages and Dendritic Cells: Manipulation of mTOR and Cellular Metabolism to Promote Immune Escape. Cells 2020; 9:cells9010161. [PMID: 31936570 PMCID: PMC7017145 DOI: 10.3390/cells9010161] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 01/01/2020] [Accepted: 01/07/2020] [Indexed: 02/06/2023] Open
Abstract
Myeloid cells, including macrophages and dendritic cells, represent an important first line of defense against infections. Upon recognition of pathogens, these cells undergo a metabolic reprogramming that supports their activation and ability to respond to the invading pathogens. An important metabolic regulator of these cells is mammalian target of rapamycin (mTOR). During infection, pathogens use host metabolic pathways to scavenge host nutrients, as well as target metabolic pathways for subversion of the host immune response that together facilitate pathogen survival. Given the pivotal role of mTOR in controlling metabolism and DC and macrophage function, pathogens have evolved strategies to target this pathway to manipulate these cells. This review seeks to discuss the most recent insights into how pathogens target DC and macrophage metabolism to subvert potential deleterious immune responses against them, by focusing on the metabolic pathways that are known to regulate and to be regulated by mTOR signaling including amino acid, lipid and carbohydrate metabolism, and autophagy.
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111
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Saavedra-García P, Martini F, Auner HW. Proteasome inhibition in multiple myeloma: lessons for other cancers. Am J Physiol Cell Physiol 2019; 318:C451-C462. [PMID: 31875696 DOI: 10.1152/ajpcell.00286.2019] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Cellular protein homeostasis (proteostasis) depends on the controlled degradation of proteins that are damaged or no longer required by the ubiquitin-proteasome system (UPS). The 26S proteasome is the principal executer of substrate-specific proteolysis in eukaryotic cells and regulates a myriad of cellular functions. Proteasome inhibitors were initially developed as chemical tools to study proteasomal function but rapidly became widely used anticancer drugs that are now used at all stages of treatment for the bone marrow cancer multiple myeloma (MM). Here, we review the mechanisms of action of proteasome inhibitors that underlie their preferential toxicity to MM cells, focusing on endoplasmic reticulum stress, depletion of amino acids, and effects on glucose and lipid metabolism. We also discuss mechanisms of resistance to proteasome inhibition such as autophagy and metabolic rewiring and what lessons we may learn from the success and failure of proteasome inhibition in MM for treating other cancers with proteostasis-targeting drugs.
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Affiliation(s)
- Paula Saavedra-García
- Cancer Cell Metabolism Group, Hugh and Josseline Langmuir Centre for Myeloma Research, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Francesca Martini
- Department of Translational Research on New Technologies in Medicine and Surgery, Hematology Unit, Ospedale Santa Chiara, Pisa, Italy
| | - Holger W Auner
- Cancer Cell Metabolism Group, Hugh and Josseline Langmuir Centre for Myeloma Research, Faculty of Medicine, Imperial College London, London, United Kingdom
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112
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Activation of General Control Nonderepressible-2 Kinase Ameliorates Glucotoxicity in Human Peritoneal Mesothelial Cells, Preserves Their Integrity, and Prevents Mesothelial to Mesenchymal Transition. Biomolecules 2019; 9:biom9120832. [PMID: 31817562 PMCID: PMC6995539 DOI: 10.3390/biom9120832] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 11/20/2019] [Accepted: 12/03/2019] [Indexed: 12/31/2022] Open
Abstract
Along with infections, ultrafiltration failure due to the toxicity of glucose-containing peritoneal dialysis (PD) solutions is the Achilles’ heel of PD method. Triggered by the protective effect of general control nonderepressible-2 (GCN-2) kinase activation against high-glucose conditions in other cell types, we evaluated whether the same occurs in human peritoneal mesothelial cells. We activated GCN-2 kinase with halofuginone or tryptophanol, and assessed the impact of this intervention on glucose transporter-1, glucose transporter-3, and sodium-glucose cotransporter-1, glucose influx, reactive oxygen species (ROS), and the events that result in glucotoxicity. These involve the inhibition of glyceraldehyde 3-phosphate dehydrogenase and the diversion of upstream glycolytic products to the aldose pathway (assessed by D-sorbitol), the lipid synthesis pathway (assessed by protein kinase C activity), the hexosamine pathway (determined by O-linked β-N-acetyl glucosamine-modified proteins), and the advanced glycation end products generation pathway (assessed by methylglyoxal). Then, we examined the production of the profibrotic transforming growth factor-β1 (TGF-β1), the pro-inflammatory interleukin-8 (IL-8). Cell apoptosis was assessed by cleaved caspase-3, and mesothelial to mesenchymal transition (MMT) was evaluated by α-smooth muscle actin protein. High-glucose conditions increased glucose transporters, glucose influx, ROS, all the high-glucose-induced harmful pathways, TGF-β1 and IL-8, cell apoptosis, and MMT. Halofuginone and tryptophanol inhibited all of the above high glucose-induced alterations, indicating that activation of GCN-2 kinase ameliorates glucotoxicity in human peritoneal mesothelial cells, preserves their integrity, and prevents MMT. Whether such a strategy could be applied in the clinic to avoid ultrafiltration failure in PD patients remains to be investigated.
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113
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Walters HA, Welter BH, Sullivan WJ, Temesvari LA. Phosphorylation of eukaryotic initiation factor-2α in response to endoplasmic reticulum and nitrosative stress in the human protozoan parasite, Entamoeba histolytica. Mol Biochem Parasitol 2019; 234:111223. [PMID: 31568804 PMCID: PMC6886254 DOI: 10.1016/j.molbiopara.2019.111223] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 09/20/2019] [Accepted: 09/23/2019] [Indexed: 12/25/2022]
Abstract
Entamoeba histolytica is an intestinal parasite infecting over 50 million people worldwide and is the causative agent of amebic dysentery and amoebic liver abscess. In the human host, E. histolytica experiences stress brought on by nutrient deprivation and the host immune response. To be a successful parasite, E. histolytica must counter the stress; therefore, understanding the stress response may uncover new drug targets. In many systems, the stress response includes down-regulation of protein translation, which is regulated by phosphorylation of eukaryotic initiation factor (eIF-2α). Previous work has demonstrated that phosphorylation of the E. histolytica eIF-2α (EheIF-2α) increases significantly when exposed to long-term serum starvation, oxidative stress, and long-term heat shock. However, the effects of reagents that are known to induce nitrosative or endoplasmic reticulum (ER) stresses, on EheIF-2α have yet to be evaluated. Nitrosative stress is part of the host's immune response and ER stress can be caused by several physiological or pathological factors. We treated E. histolytica cells with various reagents known to induce nitrosative stress (DPTA-NONOate and SNP) or ER stress (BFA and DTT). We examined the morphology of the ER, tracked phosphorylation of EheIF-2α, and assessed protein translation in control and stressed cells. While all four stress-inducing reagents caused a global reduction in protein translation, only DTT was capable of also inducing changes in the morphology of the ER (consistent with ER stress) and phosphorylation of EheIF-2α. This suggests that DTT authentically induces ER stress in E. histolytica and that this stress is managed by the eIF-2α-based system. This was supported by the observation that cells expressing a non-phosphorylatable version of eIF-2α were also highly sensitive to DTT-stress. Since protein translation decreased in the absence of phosphorylation of eIF-2α (after treatment with DPTA-NONOate, SNP or BFA), the data also indicate that there are alternative protein-translational control pathways in E. histolytica. Overall, our study further illuminates the stress response to nitrosative stress and ER stress in E. histolytica.
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Affiliation(s)
- Heather A Walters
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, 29634, United States; Eukaryotic Pathogens Innovation Center, Clemson University, Clemson, South Carolina, 29634, United States
| | - Brenda H Welter
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, 29634, United States; Eukaryotic Pathogens Innovation Center, Clemson University, Clemson, South Carolina, 29634, United States
| | - William J Sullivan
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, 46202, United States; Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN, 46202, United States
| | - Lesly A Temesvari
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, 29634, United States; Eukaryotic Pathogens Innovation Center, Clemson University, Clemson, South Carolina, 29634, United States.
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114
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Abou Hassan OK, Haidar W, Arabi M, Skouri H, Bitar F, Nemer G, Akl IB. Novel EIF2AK4 mutations in histologically proven pulmonary capillary hemangiomatosis and hereditary pulmonary arterial hypertension. BMC MEDICAL GENETICS 2019; 20:176. [PMID: 31711431 PMCID: PMC6849225 DOI: 10.1186/s12881-019-0915-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 10/28/2019] [Indexed: 12/19/2022]
Abstract
Background Pulmonary hypertension (PH) remains one of the rarest and deadliest diseases. Pulmonary Capillary Hemangiomatosis (PCH) is one of the sub-classes of PH. It was identified using histological and molecular tools and is characterized by the proliferation of capillaries into the alveolar septae. Mutations in the gene encoding the eukaryotic translation initiation factor 2 alpha kinase 4 (EIF2AK4) have recently been linked to this particular subgroup of PH. Methods In our effort to unveil the genetic basis of idiopathic and familial cases of PH in Lebanon, we have used whole exome sequencing to document known and/or novel mutations in genes that could explain the underlying phenotype. Results We showed bi-allelic mutations in EIF2AK4 in two non-consanguineous families: a novel non-sense mutation c.1672C > T (p.Q558*) and a previously documented deletion c.560_564drlAAGAA (p.K187Rfs9*). Our histological analysis coupled with the CT-scan results showed that the two patients with the p.Q558* mutation have PH. In contrast, only one of the individuals harboring the p.K187Rfs9* variant has a documented PCH while his older brother remains asymtomatic. Differential analysis of the variants in the genes of the neighboring network of EIF2AK4 between the two siblings identified a couple of interesting missense mutations that could account for this discrepancy. Conclusion These findings represent a novel documentation of the involvement of EIF2AK4 in the different aspects of pulmonary hypertension. The absence of a molecular mechanism that relates the abrogated function of the protein to the phenotype is still a major hurdle in our understanding of the disease.
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Affiliation(s)
- Ossama K Abou Hassan
- Departments of Internal Medicine, Faculty of Medicine, American University of Beirut, P.O.Box: 11-0236, Beirut, Lebanon
| | - Wiam Haidar
- Departments of Internal Medicine, Faculty of Medicine, American University of Beirut, P.O.Box: 11-0236, Beirut, Lebanon
| | - Mariam Arabi
- Departments of Pediatrics and Adolescent Medicine, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
| | - Hadi Skouri
- Departments of Internal Medicine, Faculty of Medicine, American University of Beirut, P.O.Box: 11-0236, Beirut, Lebanon
| | - Fadi Bitar
- Departments of Pediatrics and Adolescent Medicine, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
| | - Georges Nemer
- Departments of Biochemistry and Molecular Genetics, Faculty of Medicine, American University of Beirut, P.O.Box: 11-0236, Beirut, Lebanon. .,Program of Genomics and Precision Medicine, College of Health and Life Sciences, Hamad Bin Khalifa University, Doha, Qatar.
| | - Imad Bou Akl
- Departments of Internal Medicine, Faculty of Medicine, American University of Beirut, P.O.Box: 11-0236, Beirut, Lebanon.
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Le Deunff E, Beauclair P, Deleu C, Lecourt J. Inhibition of Aminotransferases by Aminoethoxyvinylglycine Triggers a Nitrogen Limitation Condition and Deregulation of Histidine Homeostasis That Impact Root and Shoot Development and Nitrate Uptake. FRONTIERS IN PLANT SCIENCE 2019; 10:1387. [PMID: 31787993 PMCID: PMC6855093 DOI: 10.3389/fpls.2019.01387] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 10/08/2019] [Indexed: 06/02/2023]
Abstract
Background and Aims: Although AVG (aminoethoxyvinylglycine) is intensely used to decipher signaling in ethylene/indol-3-acetic acid (IAA) interactions on root morphogenesis, AVG is not a specific inhibitor of aminocyclopropane-1-carboxylate synthase (ACS) and tryptophan aminotransferase (TAA) and tryptophan aminotransferase related (TAR) activities since it is able to inhibit several aminotransferases involved in N metabolism. Indeed, 1 mM glutamate (Glu) supply to the roots in plants treated with 10 μM AVG partially restores the root growth. Here, we highlight the changes induced by AVG and AVG + Glu treatments on the N metabolism impairment and root morphogenetic program. Methods: Root nitrate uptake induced by AVG and AVG + Glu treatments was measured by a differential labeling with 15NO3 - and 15Nglutamate. In parallel a profiling of amino acids (AA) was performed to decipher the impairment of AA metabolism. Key Results: 10 μM AVG treatment increases K15NO3 uptake and 15N translocation during root growth inhibition whereas 10 μM AVG + 1 mM 15Nglutamate treatment inhibits K15NO3 uptake and increases 15Nglutamate uptake during partial root growth restoration. This is explained by a nitrogen (N) limitation condition induced by AVG treatment and a N excess condition induced by AVG + Glu treatment. AA levels were mainly impaired by AVG treatment in roots, where levels of Ser, Thr, α-Ala, β-Ala, Val, Asn and His were significantly increased. His was the only amino acid for which no restoration was observed in roots and shoots after glutamate treatment suggesting important control of His homeostasis on aminotransferase network. Results were discussed in light of recent findings on the interconnection between His homeostasis and the general amino acid control system (GAAC) in eukaryotes. Conclusions: These results demonstrate that AVG concentration above 5 μM is a powerful pharmacological tool for unraveling the involvement of GAAC system or new N sensory system in morphological and metabolic changes of the roots in leguminous and non-leguminous plants.
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Affiliation(s)
| | - Patrick Beauclair
- INRA Unité Expérimentale Fourrages Environnement Ruminants (FERLUS) et Système d’Observation et d’Expérimentation pour la Recherche en Environnement (SOERE), Les Verrines CS 80006, Lusignan, France
| | - Carole Deleu
- INRA—Agrocampus Ouest—Université de Rennes 1, UMR 1349 Institut de Génétique, Environnement et Protection des Plantes (IGEPP) Université de Rennes 1, Rennes, France
| | - Julien Lecourt
- NIAB EMR, Crop Science and Production Systems New Road, East Malling, United Kingdom
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116
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Schmidt S, Gay D, Uthe FW, Denk S, Paauwe M, Matthes N, Diefenbacher ME, Bryson S, Warrander FC, Erhard F, Ade CP, Baluapuri A, Walz S, Jackstadt R, Ford C, Vlachogiannis G, Valeri N, Otto C, Schülein-Völk C, Maurus K, Schmitz W, Knight JRP, Wolf E, Strathdee D, Schulze A, Germer CT, Rosenwald A, Sansom OJ, Eilers M, Wiegering A. A MYC-GCN2-eIF2α negative feedback loop limits protein synthesis to prevent MYC-dependent apoptosis in colorectal cancer. Nat Cell Biol 2019; 21:1413-1424. [PMID: 31685988 PMCID: PMC6927814 DOI: 10.1038/s41556-019-0408-0] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 09/20/2019] [Indexed: 12/12/2022]
Abstract
Tumours depend on altered rates of protein synthesis for growth and survival, which suggests that mechanisms controlling mRNA translation may be exploitable for therapy. Here, we show that loss of APC, which occurs almost universally in colorectal tumours, strongly enhances the dependence on the translation initiation factor eIF2B5. Depletion of eIF2B5 induces an integrated stress response and enhances translation of MYC via an internal ribosomal entry site. This perturbs cellular amino acid and nucleotide pools, strains energy resources and causes MYC-dependent apoptosis. eIF2B5 limits MYC expression and prevents apoptosis in APC-deficient murine and patient-derived organoids and in APC-deficient murine intestinal epithelia in vivo. Conversely, the high MYC levels present in APC-deficient cells induce phosphorylation of eIF2α via the kinases GCN2 and PKR. Pharmacological inhibition of GCN2 phenocopies eIF2B5 depletion and has therapeutic efficacy in tumour organoids, which demonstrates that a negative MYC-eIF2α feedback loop constitutes a targetable vulnerability of colorectal tumours.
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Affiliation(s)
- Stefanie Schmidt
- Theodor Boveri Institute, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
- Department of General, Visceral, Vascular and Pediatric Surgery, University Hospital Würzburg, Würzburg, Germany
| | | | - Friedrich Wilhelm Uthe
- Theodor Boveri Institute, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
- Department of General, Visceral, Vascular and Pediatric Surgery, University Hospital Würzburg, Würzburg, Germany
| | - Sarah Denk
- Theodor Boveri Institute, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
- Department of General, Visceral, Vascular and Pediatric Surgery, University Hospital Würzburg, Würzburg, Germany
| | | | - Niels Matthes
- Theodor Boveri Institute, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
- Department of General, Visceral, Vascular and Pediatric Surgery, University Hospital Würzburg, Würzburg, Germany
| | | | | | | | - Florian Erhard
- Institute for Virology and Immunobiology, University of Würzburg, Würzburg, Germany
| | - Carsten Patrick Ade
- Theodor Boveri Institute, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
| | - Apoorva Baluapuri
- Theodor Boveri Institute, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
| | - Susanne Walz
- Comprehensive Cancer Center Mainfranken, Core Unit Bioinformatics, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
| | | | | | | | - Nicola Valeri
- Division of Molecular Pathology, The Institute of Cancer Research, London, UK
- Department of Medicine, The Royal Marsden NHS Trust, London, UK
| | - Christoph Otto
- Department of General, Visceral, Vascular and Pediatric Surgery, University Hospital Würzburg, Würzburg, Germany
| | | | - Katja Maurus
- Comprehensive Cancer Center Mainfranken, University of Würzburg, Würzburg, Germany
| | - Werner Schmitz
- Theodor Boveri Institute, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
| | | | - Elmar Wolf
- Theodor Boveri Institute, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
| | | | - Almut Schulze
- Theodor Boveri Institute, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
- Comprehensive Cancer Center Mainfranken, University of Würzburg, Würzburg, Germany
| | - Christoph-Thomas Germer
- Department of General, Visceral, Vascular and Pediatric Surgery, University Hospital Würzburg, Würzburg, Germany
- Comprehensive Cancer Center Mainfranken, University of Würzburg, Würzburg, Germany
| | - Andreas Rosenwald
- Comprehensive Cancer Center Mainfranken, University of Würzburg, Würzburg, Germany
| | - Owen James Sansom
- CRUK Beatson Institute, Glasgow, UK
- Institute of Cancer Sciences, University of Glasgow, Glasgow, UK
| | - Martin Eilers
- Theodor Boveri Institute, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany.
- Comprehensive Cancer Center Mainfranken, University of Würzburg, Würzburg, Germany.
| | - Armin Wiegering
- Theodor Boveri Institute, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany.
- Department of General, Visceral, Vascular and Pediatric Surgery, University Hospital Würzburg, Würzburg, Germany.
- Comprehensive Cancer Center Mainfranken, University of Würzburg, Würzburg, Germany.
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CD98hc (SLC3A2) sustains amino acid and nucleotide availability for cell cycle progression. Sci Rep 2019; 9:14065. [PMID: 31575908 PMCID: PMC6773781 DOI: 10.1038/s41598-019-50547-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 09/13/2019] [Indexed: 12/13/2022] Open
Abstract
CD98 heavy chain (CD98hc) forms heteromeric amino acid (AA) transporters by interacting with different light chains. Cancer cells overexpress CD98hc-transporters in order to meet their increased nutritional and antioxidant demands, since they provide branched-chain AA (BCAA) and aromatic AA (AAA) availability while protecting cells from oxidative stress. Here we show that BCAA and AAA shortage phenocopies the inhibition of mTORC1 signalling, protein synthesis and cell proliferation caused by CD98hc ablation. Furthermore, our data indicate that CD98hc sustains glucose uptake and glycolysis, and, as a consequence, the pentose phosphate pathway (PPP). Thus, loss of CD98hc triggers a dramatic reduction in the nucleotide pool, which leads to replicative stress in these cells, as evidenced by the enhanced DNA Damage Response (DDR), S-phase delay and diminished rate of mitosis, all recovered by nucleoside supplementation. In addition, proper BCAA and AAA availability sustains the expression of the enzyme ribonucleotide reductase. In this regard, BCAA and AAA shortage results in decreased content of deoxynucleotides that triggers replicative stress, also recovered by nucleoside supplementation. On the basis of our findings, we conclude that CD98hc plays a central role in AA and glucose cellular nutrition, redox homeostasis and nucleotide availability, all key for cell proliferation.
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Fission Yeast Asc1 Stabilizes the Interaction between Eukaryotic Initiation Factor 3a and Rps0A/uS2 for Protein Synthesis. Mol Cell Biol 2019; 39:MCB.00161-19. [PMID: 31285271 DOI: 10.1128/mcb.00161-19] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 06/29/2019] [Indexed: 12/17/2022] Open
Abstract
Aminoacyl-tRNA synthetase cofactors play important roles in coordinating aminoacylation and translation. In this study, we describe an additional function of the fission yeast aminoacyl-tRNA synthetase cofactor 1 (Asc1) in translation. We found that Asc1 directly binds and stabilizes the interaction between small ribosomal protein Rps0A/uS2 and eukaryotic initiation factor 3a (eIF3a). In the absence of Asc1, the interaction between eIF3a and Rps0A/uS2 was compromised. The interaction between Rps0A/uS2 and eIF3a mediated the 40S ribosomal subunit binding of eIF3 in 43S preinitiation complex formation to stimulate translation initiation. Keeping with this idea, in an asc1 mutant, the association of mRNA with the 40S ribosomal subunit was defective and protein synthesis was compromised. To show that Asc1 is directly involved in translation, we demonstrate that the addition of recombinant Asc1 is able to rescue the translation defect of the asc1 mutant in a cell-free system. Furthermore, this function of Asc1 is likely to be evolutionarily conserved, as a similar interaction with eIF3a and Rps0A/uS2 could be identified in the budding yeast Saccharomyces cerevisiae and human aminoacyl-tRNA synthetase cofactors. Together, these results identify a function of aminoacyl-tRNA synthetase cofactors in translation preinitiation complex formation, which adds significantly to the expanded functions associated with aminoacyl-tRNA synthetases and their cofactors.
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Guerra BA, Brandão BB, Pinto SS, Salgueiro WG, De-Souza EA, Reis FCG, Batista TM, Cavalcante-Silva V, D'Almeida V, Castilho BA, Carneiro EM, Antebi A, Festuccia WT, Mori MA. Dietary sulfur amino acid restriction upregulates DICER to confer beneficial effects. Mol Metab 2019; 29:124-135. [PMID: 31668384 PMCID: PMC6745493 DOI: 10.1016/j.molmet.2019.08.017] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 08/22/2019] [Accepted: 08/24/2019] [Indexed: 12/21/2022] Open
Abstract
Objective Dietary restriction (DR) improves health and prolongs lifespan in part by upregulating type III endoribonuclease DICER in adipose tissue. In this study, we aimed to specifically test which missing dietary component was responsible for DICER upregulation. Methods We performed a nutrient screen in mouse preadipocytes and validated the results in vivo using different kinds of dietary interventions in wild type or genetically modified mice and worms, also testing the requirement of DICER on the effects of the diets. Results We found that sulfur amino acid restriction (i.e., methionine or cysteine) is sufficient to increase Dicer mRNA expression in preadipocytes. Consistently, while DR increases DICER expression in adipose tissue of mice, this effect is blunted by supplementation of the diet with methionine, cysteine, or casein, but not with a lipid or carbohydrate source. Accordingly, dietary methionine or protein restriction mirrors the effects of DR. These changes are associated with alterations in serum adiponectin. We also found that DICER controls and is controlled by adiponectin. In mice, DICER plays a role in methionine restriction-induced upregulation of Ucp1 in adipose tissue. In C. elegans, DR and a model of methionine restriction also promote DICER expression in the intestine (an analog of the adipose tissue) and prolong lifespan in a DICER-dependent manner. Conclusions We propose an evolutionary conserved mechanism in which dietary sulfur amino acid restriction upregulates DICER levels in adipose tissue leading to beneficial health effects. DICER is upregulated in adipose tissue by dietary sulfur amino acid restriction. Adiponectin and DICER co-regulate each other in adipocytes. Methionine restriction requires DICER to promote adipose tissue browning. DICER is upregulated in Caenorhabditis elegans intestine upon dietary restriction. Methionine restriction requires DICER to prolong lifespan in C. elegans.
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Affiliation(s)
- Beatriz A Guerra
- Department of Biophysics, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil; Program in Molecular Biology, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil; Department of Biochemistry and Tissue Biology, Instituto de Biologia, Universidade Estadual de Campinas, Brazil
| | - Bruna B Brandão
- Department of Biophysics, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil; Program in Molecular Biology, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Silas S Pinto
- Department of Biophysics, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil; Program in Molecular Biology, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil; Department of Biochemistry and Tissue Biology, Instituto de Biologia, Universidade Estadual de Campinas, Brazil; Program in Genetics and Molecular Biology, Instituto de Biologia, Universidade Estadual de Campinas, Brazil
| | - Willian G Salgueiro
- Department of Biochemistry and Tissue Biology, Instituto de Biologia, Universidade Estadual de Campinas, Brazil; Program in Genetics and Molecular Biology, Instituto de Biologia, Universidade Estadual de Campinas, Brazil
| | - Evandro A De-Souza
- Department of Biophysics, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil; Program in Molecular Biology, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil; Institute of Medical Biochemistry Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Brazil
| | - Felipe C G Reis
- Department of Biophysics, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Thiago M Batista
- Department of Structure and Functional Biology, Instituto de Biologia, Universidade Estadual de Campinas, Brazil
| | - Vanessa Cavalcante-Silva
- Department of Psychobiology, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Vânia D'Almeida
- Department of Psychobiology, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Beatriz A Castilho
- Department of Microbiology, Immunology and Parasitology, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Everardo M Carneiro
- Department of Structure and Functional Biology, Instituto de Biologia, Universidade Estadual de Campinas, Brazil
| | - Adam Antebi
- Max-Planck Institute for Biology of Ageing, Cologne, and CECAD, University of Cologne, Cologne, Germany
| | - William T Festuccia
- Department of Physiology, Instituto de Ciências Biomédicas, Universidade de São Paulo, Brazil
| | - Marcelo A Mori
- Department of Biophysics, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil; Program in Molecular Biology, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil; Department of Biochemistry and Tissue Biology, Instituto de Biologia, Universidade Estadual de Campinas, Brazil; Program in Genetics and Molecular Biology, Instituto de Biologia, Universidade Estadual de Campinas, Brazil.
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120
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Nishikawa S, Itoh Y, Tokugawa M, Inoue Y, Nakashima KI, Hori Y, Miyajima C, Yoshida K, Morishita D, Ohoka N, Inoue M, Mizukami H, Makino T, Hayashi H. Kurarinone from Sophora Flavescens Roots Triggers ATF4 Activation and Cytostatic Effects Through PERK Phosphorylation. Molecules 2019; 24:E3110. [PMID: 31461933 PMCID: PMC6749437 DOI: 10.3390/molecules24173110] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 08/23/2019] [Accepted: 08/23/2019] [Indexed: 01/28/2023] Open
Abstract
In response to cellular stresses, activating transcriptional factor 4 (ATF4) regulates the expression of both stress-relieving genes and apoptosis-inducing genes, eliciting cell fate determination. Since pharmacological activation of ATF4 exerts potent anti-tumor effects, modulators of ATF4 activation may have potential in cancer therapy. We herein attempted to identify small molecules that activate ATF4. A cell-based screening to monitor TRB3 promoter activation was performed using crude drugs used in traditional Japanese Kampo medicine. We found that an extract from Sophora flavescens roots exhibited potent TRB3 promoter activation. The activity-guided fractionation revealed that kurarinone was identified as the active ingredient. Intriguingly, ATF4 activation in response to kurarinone required PKR-like endoplasmic reticulum kinase (PERK). Moreover, kurarinone induced the cyclin-dependent kinase inhibitor p21 as well as cytostasis in cancer cells. Importantly, the cytostatic effect of kurarinone was reduced by pharmacological inhibition of PERK. These results indicate that kurarinone triggers ATF4 activation through PERK and exerts cytostatic effects on cancer cells. Taken together, our results suggest that modulation of the PERK-ATF4 pathway with kurarinone has potential as a cancer treatment.
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Affiliation(s)
- Sakiko Nishikawa
- Department of Cell Signaling, Graduate School of Pharmaceutical Sciences and Nagoya City University, Nagoya 467-8603, Japan
| | - Yuka Itoh
- Department of Cell Signaling, Graduate School of Pharmaceutical Sciences and Nagoya City University, Nagoya 467-8603, Japan
- Department of Biochemistry, Graduate School of Medicine, University of Yamanashi, Yamanashi 409-3898, Japan
| | - Muneshige Tokugawa
- Department of Cell Signaling, Graduate School of Pharmaceutical Sciences and Nagoya City University, Nagoya 467-8603, Japan
| | - Yasumichi Inoue
- Department of Cell Signaling, Graduate School of Pharmaceutical Sciences and Nagoya City University, Nagoya 467-8603, Japan.
- Department of Innovative Therapeutic Sciences, Cooperative Major in Nanopharmaceutical Sciences, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan.
| | - Ken-Ichi Nakashima
- Laboratory of Medicinal Resources, School of Pharmacy, Aichi Gakuin University, Nagoya 464-8650, Japan
| | - Yuka Hori
- Department of Cell Signaling, Graduate School of Pharmaceutical Sciences and Nagoya City University, Nagoya 467-8603, Japan
| | - Chiharu Miyajima
- Department of Cell Signaling, Graduate School of Pharmaceutical Sciences and Nagoya City University, Nagoya 467-8603, Japan
- Department of Innovative Therapeutic Sciences, Cooperative Major in Nanopharmaceutical Sciences, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
| | - Kou Yoshida
- Department of Cell Signaling, Graduate School of Pharmaceutical Sciences and Nagoya City University, Nagoya 467-8603, Japan
| | - Daisuke Morishita
- Department of Cell Signaling, Graduate School of Pharmaceutical Sciences and Nagoya City University, Nagoya 467-8603, Japan
| | - Nobumichi Ohoka
- Division of Molecular Target and Gene Therapy Products, National Institute of Health Sciences, Kanagawa 210-9501, Japan
| | - Makoto Inoue
- Laboratory of Medicinal Resources, School of Pharmacy, Aichi Gakuin University, Nagoya 464-8650, Japan
| | - Hajime Mizukami
- Department of Pharmacognosy, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
| | - Toshiaki Makino
- Department of Pharmacognosy, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
| | - Hidetoshi Hayashi
- Department of Cell Signaling, Graduate School of Pharmaceutical Sciences and Nagoya City University, Nagoya 467-8603, Japan.
- Department of Innovative Therapeutic Sciences, Cooperative Major in Nanopharmaceutical Sciences, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan.
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Liu X, Afrin T, Pajerowska-Mukhtar KM. Arabidopsis GCN2 kinase contributes to ABA homeostasis and stomatal immunity. Commun Biol 2019; 2:302. [PMID: 31428690 PMCID: PMC6687712 DOI: 10.1038/s42003-019-0544-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 06/28/2019] [Indexed: 12/28/2022] Open
Abstract
General Control Non-derepressible 2 (GCN2) is an evolutionarily conserved serine/threonine kinase that modulates amino acid homeostasis in response to nutrient deprivation in yeast, human and other eukaryotes. However, the GCN2 signaling pathway in plants remains largely unknown. Here, we demonstrate that in Arabidopsis, bacterial infection activates AtGCN2-mediated phosphorylation of eIF2α and promotes TBF1 translational derepression. Consequently, TBF1 regulates a subset of abscisic acid signaling components to modulate pre-invasive immunity. We show that GCN2 fine-tunes abscisic acid accumulation and signaling during both pre-invasive and post-invasive stages of an infection event. Finally, we also demonstrate that AtGCN2 participates in signaling triggered by phytotoxin coronatine secreted by P. syringae. During the preinvasive phase, AtGCN2 regulates stomatal immunity by affecting pathogen-triggered stomatal closure and coronatine-mediated stomatal reopening. Our conclusions support a conserved role of GCN2 in various forms of immune responses across kingdoms, highlighting GCN2's importance in studies on both plant and mammalian immunology.
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Affiliation(s)
- Xiaoyu Liu
- Department of Biology, University of Alabama at Birmingham, 1300 University Blvd., Birmingham, AL 35294 USA
- Present Address: Bayer Crop Science, 800 N Lindbergh Blvd., Creve Coeur, MO 63144 USA
| | - Taiaba Afrin
- Department of Biology, University of Alabama at Birmingham, 1300 University Blvd., Birmingham, AL 35294 USA
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Mladenović D, Radosavljević T, Hrnčić D, Rasic-Markovic A, Stanojlović O. The effects of dietary methionine restriction on the function and metabolic reprogramming in the liver and brain - implications for longevity. Rev Neurosci 2019; 30:581-593. [PMID: 30817309 DOI: 10.1515/revneuro-2018-0073] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 10/26/2018] [Indexed: 02/05/2023]
Abstract
Methionine is an essential sulphur-containing amino acid involved in protein synthesis, regulation of protein function and methylation reactions. Dietary methionine restriction (0.12-0.17% methionine in food) extends the life span of various animal species and delays the onset of aging-associated diseases and cancers. In the liver, methionine restriction attenuates steatosis and delays the development of non-alcoholic steatohepatitis due to antioxidative action and metabolic reprogramming. The limited intake of methionine stimulates the fatty acid oxidation in the liver and the export of lipoproteins as well as inhibits de novo lipogenesis. These effects are mediated by various signaling pathways and effector molecules, including sirtuins, growth hormone/insulin-like growth factor-1 axis, sterol regulatory element binding proteins, adenosine monophosphate-dependent kinase and general control nonderepressible 2 pathway. Additionally, methionine restriction stimulates the synthesis of fibroblast growth factor-21 in the liver, which increases the insulin sensitivity of peripheral tissues. In the brain, methionine restriction delays the onset of neurodegenerative diseases and increases the resistance to various forms of stress through antioxidative effects and alterations in lipid composition. This review aimed to summarize the morphological, functional and molecular changes in the liver and brain caused by the methionine restriction, with possible implications in the prolongation of maximal life span.
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Affiliation(s)
- Dušan Mladenović
- Institute of Pathophysiology 'Ljubodrag Buba Mihailovic', Faculty of Medicine, University of Belgrade, Dr Subotica 9, 11000 Belgrade, Serbia
| | - Tatjana Radosavljević
- Institute of Pathophysiology 'Ljubodrag Buba Mihailovic', Faculty of Medicine, University of Belgrade, Dr Subotica 9, 11000 Belgrade, Serbia
| | - Dragan Hrnčić
- Institute of Medical Physiology 'Richard Burian', Faculty of Medicine, University of Belgrade, Višegradska 26/II, 11000 Belgrade, Serbia
| | - Aleksandra Rasic-Markovic
- Institute of Medical Physiology 'Richard Burian', Faculty of Medicine, University of Belgrade, Višegradska 26/II, 11000 Belgrade, Serbia
| | - Olivera Stanojlović
- Institute of Medical Physiology 'Richard Burian', Faculty of Medicine, University of Belgrade, Višegradska 26/II, 11000 Belgrade, Serbia
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Pant A, Cao S, Yang Z. Asparagine Is a Critical Limiting Metabolite for Vaccinia Virus Protein Synthesis during Glutamine Deprivation. J Virol 2019; 93:e01834-18. [PMID: 30996100 PMCID: PMC6580962 DOI: 10.1128/jvi.01834-18] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2018] [Accepted: 04/07/2019] [Indexed: 12/13/2022] Open
Abstract
Viruses actively interact with host metabolism because viral replication relies on host cells to provide nutrients and energy. Vaccinia virus (VACV; the prototype poxvirus) prefers glutamine to glucose for efficient replication to the extent that VACV replication is hindered in glutamine-free medium. Remarkably, our data show that VACV replication can be fully rescued from glutamine depletion by asparagine supplementation. By global metabolic profiling, as well as genetic and chemical manipulation of the asparagine supply, we provide evidence demonstrating that the production of asparagine, which exclusively requires glutamine for biosynthesis, accounts for VACV's preference of glutamine to glucose rather than glutamine's superiority over glucose in feeding the tricarboxylic acid (TCA) cycle. Furthermore, we show that sufficient asparagine supply is required for efficient VACV protein synthesis. Our study highlights that the asparagine supply, the regulation of which has been evolutionarily tailored in mammalian cells, presents a critical barrier to VACV replication due to a high asparagine content of viral proteins and a rapid demand of viral protein synthesis. The identification of asparagine availability as a critical limiting factor for efficient VACV replication suggests a new direction of antiviral strategy development.IMPORTANCE Viruses rely on their infected host cells to provide nutrients and energy for replication. Vaccinia virus, the prototypic member of the poxviruses, which comprise many significant human and animal pathogens, prefers glutamine to glucose for efficient replication. Here, we show that the preference is not because glutamine is superior to glucose as the carbon source to fuel the tricarboxylic acid cycle for vaccinia virus replication. Rather interestingly, the preference is because the asparagine supply for efficient viral protein synthesis becomes limited in the absence of glutamine, which is necessary for asparagine biosynthesis. We provide further genetic and chemical evidence to demonstrate that asparagine availability plays a critical role in efficient vaccinia virus replication. This discovery identifies a weakness of vaccinia virus and suggests a possible direction to intervene in poxvirus infection.
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Affiliation(s)
- Anil Pant
- Division of Biology, Kansas State University, Manhattan, Kansas, USA
| | - Shuai Cao
- Division of Biology, Kansas State University, Manhattan, Kansas, USA
| | - Zhilong Yang
- Division of Biology, Kansas State University, Manhattan, Kansas, USA
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Pereira CM, Filev R, Dubiela FP, Brandão BB, Queiroz CM, Ludwig RG, Hipolide D, Longo BM, Mello LE, Mori MA, Castilho BA. The GCN2 inhibitor IMPACT contributes to diet-induced obesity and body temperature control. PLoS One 2019; 14:e0217287. [PMID: 31166980 PMCID: PMC6550387 DOI: 10.1371/journal.pone.0217287] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2018] [Accepted: 05/08/2019] [Indexed: 12/20/2022] Open
Abstract
IMPACT, a highly conserved protein, is an inhibitor of the eIF2α kinase GCN2. In mammals, it is preferentially expressed in neurons. Knock-down of IMPACT expression in neuronal cells increases basal GCN2 activation and eIF2α phosphorylation and decreases translation initiation. In the mouse brain, IMPACT is particularly abundant in the hypothalamus. Here we describe that the lack of IMPACT in mice affects hypothalamic functions. Impact-/- mice (Imp-KO) are viable and have no apparent major phenotypic defect. The hypothalamus in these animals shows increased levels of eIF2α phosphorylation, as expected from the described role of IMPACT in inhibiting GCN2 and from its abundance in this brain region. When fed a normal chow, animals lacking IMPACT weight slightly less than wild-type mice. When fed a high-fat diet, Imp-KO animals gain substantially less weight due to lower food intake when compared to wild-type mice. STAT3 signaling was depressed in Imp-KO animals even though leptin levels were identical to the wild-type mice. This finding supports the observation that Imp-KO mice have defective thermoregulation upon fasting. This phenotype was partially dependent on GCN2, whereas the lean phenotype was independent of GCN2. Taken together, our results indicate that IMPACT contributes to GCN2-dependent and -independent mechanisms involved in the regulation of autonomic functions in response to energy availability.
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Affiliation(s)
- Catia M. Pereira
- Department of Microbiology, Immunology and Parasitology, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Renato Filev
- Department of Physiology, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Francisco P. Dubiela
- Department of Psychobiology, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Bruna B. Brandão
- Department of Biophysics, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Claudio M. Queiroz
- Brain Institute, Universidade Federal do Rio Grande do Norte, Natal, Brazil
| | - Raissa G. Ludwig
- Department of Biochemistry and Tissue Biology, UNICAMP, Campinas, Brazil
| | - Debora Hipolide
- Department of Psychobiology, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Beatriz M. Longo
- Department of Physiology, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Luiz E. Mello
- Department of Physiology, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Marcelo A. Mori
- Department of Biophysics, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Beatriz A. Castilho
- Department of Microbiology, Immunology and Parasitology, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
- * E-mail:
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Nutrient Sensing and Redox Balance: GCN2 as a New Integrator in Aging. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2019; 2019:5730532. [PMID: 31249645 PMCID: PMC6556294 DOI: 10.1155/2019/5730532] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 04/21/2019] [Indexed: 02/05/2023]
Abstract
Aging is a complex process in which the accumulation of molecular, cellular, and organism dysfunction increases the probability of death. Several pieces of evidence have revealed a contribution of stress responses in aging and in aging-related diseases, in particular, the key role of signaling pathways associated to nutritional stress. Here, we review the possible interplay between amino acid sensing and redox balance maintenance mediated by the nutritional sensor general control nonderepressive 2 (GCN2). We discuss this new dimension of nutritional stress sensing consequences, standing out GCN2 as a central coordinator of key cellular processes that assure healthy homeostasis in the cell, raising GCN2 as a novel interesting target, that when activated, could imply pleiotropic benefits, particularly GCN2 intervention and its new unexplored therapeutic role as a player in the aging process.
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Parzych K, Saavedra-García P, Valbuena GN, Al-Sadah HA, Robinson ME, Penfold L, Kuzeva DM, Ruiz-Tellez A, Loaiza S, Holzmann V, Caputo V, Johnson DC, Kaiser MF, Karadimitris A, Lam EWF, Chevet E, Feldhahn N, Keun HC, Auner HW. The coordinated action of VCP/p97 and GCN2 regulates cancer cell metabolism and proteostasis during nutrient limitation. Oncogene 2019; 38:3216-3231. [PMID: 30626938 PMCID: PMC6756015 DOI: 10.1038/s41388-018-0651-z] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 12/05/2018] [Accepted: 12/07/2018] [Indexed: 12/30/2022]
Abstract
VCP/p97 regulates numerous cellular functions by mediating protein degradation through its segregase activity. Its key role in governing protein homoeostasis has made VCP/p97 an appealing anticancer drug target. Here, we provide evidence that VCP/p97 acts as a regulator of cellular metabolism. We found that VCP/p97 was tied to multiple metabolic processes on the gene expression level in a diverse range of cancer cell lines and in patient-derived multiple myeloma cells. Cellular VCP/p97 dependency to maintain proteostasis was increased under conditions of glucose and glutamine limitation in a range of cancer cell lines from different tissues. Moreover, glutamine depletion led to increased VCP/p97 expression, whereas VCP/p97 inhibition perturbed metabolic processes and intracellular amino acid turnover. GCN2, an amino acid-sensing kinase, attenuated stress signalling and cell death triggered by VCP/p97 inhibition and nutrient shortages and modulated ERK activation, autophagy, and glycolytic metabolite turnover. Together, our data point to an interconnected role of VCP/p97 and GCN2 in maintaining cancer cell metabolic and protein homoeostasis.
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Affiliation(s)
- Katarzyna Parzych
- Cancer Cell Protein Metabolism Group, Centre for Haematology, Department of Medicine, Imperial College London, London, UK
| | - Paula Saavedra-García
- Cancer Cell Protein Metabolism Group, Centre for Haematology, Department of Medicine, Imperial College London, London, UK
| | - Gabriel N Valbuena
- Division of Cancer, Department of Surgery and Cancer, Imperial College London, Hammersmith Hospital, London, UK
| | - Hibah A Al-Sadah
- Cancer Cell Protein Metabolism Group, Centre for Haematology, Department of Medicine, Imperial College London, London, UK
| | - Mark E Robinson
- Centre for Haematology, Department of Medicine, Imperial College London, London, UK
| | - Lucy Penfold
- Cancer Cell Protein Metabolism Group, Centre for Haematology, Department of Medicine, Imperial College London, London, UK
| | - Desislava M Kuzeva
- Cancer Cell Protein Metabolism Group, Centre for Haematology, Department of Medicine, Imperial College London, London, UK
| | - Angie Ruiz-Tellez
- Cancer Cell Protein Metabolism Group, Centre for Haematology, Department of Medicine, Imperial College London, London, UK
| | - Sandra Loaiza
- Cancer Cell Protein Metabolism Group, Centre for Haematology, Department of Medicine, Imperial College London, London, UK
| | - Viktoria Holzmann
- Cancer Cell Protein Metabolism Group, Centre for Haematology, Department of Medicine, Imperial College London, London, UK
| | - Valentina Caputo
- Centre for Haematology, Department of Medicine, Imperial College London, London, UK
| | - David C Johnson
- Division of Molecular Pathfology, Institute of Cancer Research, Sutton, UK
| | - Martin F Kaiser
- Division of Molecular Pathfology, Institute of Cancer Research, Sutton, UK
| | | | - Eric W-F Lam
- Division of Cancer, Department of Surgery and Cancer, Imperial College London, Hammersmith Hospital, London, UK
| | - Eric Chevet
- INSERM U1242, Chemistry, Oncogenesis, Stress, Signaling, Université de Rennes 1, Rennes, France
- Centre de Lutte Contre le Cancer Eugène Marquis Rennes, Rennes, France
| | - Niklas Feldhahn
- Centre for Haematology, Department of Medicine, Imperial College London, London, UK
| | - Hector C Keun
- Division of Cancer, Department of Surgery and Cancer, Imperial College London, Hammersmith Hospital, London, UK
| | - Holger W Auner
- Cancer Cell Protein Metabolism Group, Centre for Haematology, Department of Medicine, Imperial College London, London, UK.
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Stretton C, Lipina C, Hyde R, Cwiklinski E, Hoffmann TM, Taylor PM, Hundal HS. CDK7 is a component of the integrated stress response regulating SNAT2 (SLC38A2)/System A adaptation in response to cellular amino acid deprivation. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1866:978-991. [PMID: 30857869 PMCID: PMC6456927 DOI: 10.1016/j.bbamcr.2019.03.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 03/04/2019] [Accepted: 03/06/2019] [Indexed: 12/31/2022]
Abstract
Extracellular amino acid (AA) withdrawal/restriction invokes an integrated stress response (ISR) that induces global suppression of protein synthesis whilst allowing transcription and translation of a select group of genes, whose protein products facilitate cellular adaptation to AA insufficiency. Transcriptional induction of the System A/SNAT2 AA transporter represents a classic adaptation response and crucially depends upon activation of the General Control Nonderepressible-2 kinase/Activating transcription factor 4 (GCN2/ATF4) pathway. However, the ISR may also include additional signalling inputs operating in conjunction or independently of GCN2/ATF4 to upregulate SNAT2. Herein, we show that whilst pharmacological inhibition of MEK-ERK, mTORC1 and p38 MAP kinase signalling has no detectable effect on System A upregulation, inhibitors targeting GSK3 (e.g. SB415286) caused significant repression of the SNAT2 adaptation response. Strikingly, the effects of SB415286 persist in cells in which GSK3α/β have been stably silenced indicating an off-target effect. We show that SB415286 can also inhibit cyclin-dependent kinases (CDK) and that roscovitine and flavopiridol (two pan CDK inhibitors) are effective repressors of the SNAT2 adaptive response. In particular, our work reveals that CDK7 activity is upregulated in AA-deprived cells in a GCN-2-dependent manner and that a potent and selective CDK7 inhibitor, THZ-1, not only attenuates the increase in ATF4 expression but blocks System A adaptation. Importantly, the inhibitory effects of THZ-1 on System A adaptation are mitigated in cells expressing a doxycycline-inducible drug-resistant form of CDK7. Our data identify CDK7 as a novel component of the ISR regulating System A adaptation in response to AA insufficiency. Roscovitine and flavopiridol (CDK inhibitors) block the System A adaptive response. Extracellular amino acid (AA) withdrawal induces CDK7 activation. Pharmacological inhibition of GCN2 represses CDK7 activation in AA-deprived cells. Targeted suppression of CDK7 represses ATF4 expression and System A adaptation.
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Affiliation(s)
- Clare Stretton
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Christopher Lipina
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Russell Hyde
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Emma Cwiklinski
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Thorsten M Hoffmann
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Peter M Taylor
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Harinder S Hundal
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK.
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Volloch V, Rits-Volloch S. News from Mars: Two-Tier Paradox, Intracellular PCR, Chimeric Junction Shift, Dark Matter mRNA and Other Remarkable Features of Mammalian RNA-Dependent mRNA Amplification. Implications for Alzheimer's Disease, RNA-Based Vaccines and mRNA Therapeutics. ACTA ACUST UNITED AC 2019; 2:131-173. [PMID: 33942036 DOI: 10.33597/aimm.02-1009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Molecular Biology, a branch of science established to examine the flow of information from "letters" encrypted into DNA structure to functional proteins, was initially defined by a concept of DNA-to-RNA-to-Protein information movement, a notion termed the Central Dogma of Molecular Biology. RNA-dependent mRNA amplification, a novel mode of eukaryotic protein-encoding RNA-to-RNA-to-Protein genomic information transfer, constitutes the extension of the Central Dogma in the context of mammalian cells. It was shown to occur in cellular circumstances requiring exceptionally high levels of production of specific polypeptides, e.g. globin chains during erythroid differentiation or defined secreted proteins in the context of extracellular matrix deposition. Its potency is reflected in the observed cellular levels of the resulting amplified mRNA product: At the peak of the erythroid differentiation, for example, the amount of globin mRNA produced in the amplification pathway is about 1500-fold higher than the amount of its conventionally generated counterpart in the same cells. The cellular enzymatic machinery at the core of this process, RNA-dependent RNA polymerase activity (RdRp), albeit in a non-conventional form, was shown to be constitutively and ubiquitously present, and RNA-dependent RNA synthesis (RdRs) appeared to regularly occur, in mammalian cells. Under most circumstances, the mammalian RdRp activity produces only short antisense RNA transcripts. Generation of complete antisense RNA transcripts and amplification of mRNA molecules require the activation of inducible components of the mammalian RdRp complex. The mechanism of such activation is not clear. The present article suggests that it is triggered by a variety of cellular stresses and occurs in the context of stress responses in general and within the framework of the integrated stress response (ISR) in particular. In this process, various cellular stresses activate, in a stress type-specific manner, defined members of the mammalian translation initiation factor 2α, eIF2α, kinase family: PKR, GCN2, PERK and HRI. Any of these kinases, in an activated form, phosphorylates eIF2α. This results in suppression of global cellular protein synthesis but also in activation of expression of select group of transcription factors including ATF4, ATF5 and CHOP. These transcription factors either function as inducible components of the RdRp complex or enable their expression. The assembly of the competent RdRp complex activates mammalian RNA-dependent mRNA amplification, which appears to be a two-tier process. Tier One is a "chimeric" pathway, named so because it results in an amplified chimeric mRNA molecule containing a fragment of the antisense RNA strand at its 5' terminus. Tier Two further amplifies one of the two RNA end products of the chimeric pathway and constitutes the physiologically occurring intracellular polymerase chain reaction, iPCR. Depending on the structure of the initial mRNA amplification progenitor, the chimeric pathway, Tier One, may result in multiple outcomes including chimeric mRNA that produces either a polypeptide identical to the original, conventional mRNA progenitor-encoded protein or only its C-terminal fragment, CTF. The chimeric RNA end product of Tier One may also produce a polypeptide that is non-contiguously encoded in the genome, activate translation from an open reading frame, which is "silent" in a conventionally transcribed mRNA, or initiate an abortive translation. In sharp contrast, regardless of the outcome of Tier One, the mRNA end product of Tier Two of mammalian mRNA amplification, the iPCR pathway, always produces a polypeptide identical to a conventional mRNA progenitor-encoded protein. This discordance is referred to as the Two-Tier Paradox and discussed in detail in the present article. On the other hand, both Tiers are similar in that they result in heavily modified mRNA molecules resistant to reverse transcription, undetectable by reverse transcription-based methods of sequencing and therefore constituting a proverbial "Dark Matter" mRNA, despite being highly ubiquitous. It appears that in addition to their other functions, the modifications of the amplified mRNA render it compatible, unlike the bulk of cellular mRNA, with phosphorylated eIF2α in translation, implying that in addition to being extraordinarily abundant due to the method of its generation, amplified mRNA is also preferentially translated under the ISR conditions, thus augmenting the efficiency of the amplification process. The vital importance of powerful mechanisms of amplification of protein-encoding genomic information in normal physiology is self-evident. Their malfunctions or misuse appear to be associated with two types of abnormalities, the deficiency of a protein normally produced by these mechanisms and the mRNA amplification-mediated overproduction of a protein normally not generated by such a process. Certain classes of beta-thalassemia exemplify the first type, whereas the second type is represented by overproduction of beta-amyloid in Alzheimer's disease. Moreover, the proposed mechanism of Alzheimer's disease allows a crucial and verifiable prediction, namely that the disease-causing intraneuronally retained variant of beta-amyloid differs from that produced conventionally by βAPP proteolysis in that it contains the additional methionine or acetylated methionine at its N-terminus. Because of its extraordinary evidential value as a natural reporter of the mRNA amplification pathway, this feature, if proven, would, arguably, constitute the proverbial Holy Grail not only for Alzheimer's disease but also for the mammalian RNA-dependent mRNA amplification field in general. Both examples are discussed in detail in the present article, which summarizes and systematizes our current understanding of the field and describes two categories of reporter constructs, one for the chimeric Tier of mRNA amplification, another for the iPCR pathway; both reporter types are essential for elucidating underlying molecular mechanisms. It also suggests, in light of the recently demonstrated feasibility of RNA-based vaccines, that the targeted intracellular amplification of exogenously introduced amplification-eligible antigen-encoding mRNAs via the induced or naturally occurring RNA-dependent mRNA amplification pathway could be of substantial benefit in triggering a fast and potent immune response and instrumental in the development of future vaccines. Similar approaches can also be effective in achieving efficient and sustained expression of exogenous mRNA in mRNA therapeutics.
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Affiliation(s)
- Vladimir Volloch
- Department of Developmental Biology, Harvard School of Dental Medicine, USA
| | - Sophia Rits-Volloch
- Division of Molecular Medicine, Children's Hospital, USA.,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, USA
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Is Gcn4-induced autophagy the ultimate downstream mechanism by which hormesis extends yeast replicative lifespan? Curr Genet 2019; 65:717-720. [PMID: 30673825 DOI: 10.1007/s00294-019-00936-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Revised: 01/08/2019] [Accepted: 01/11/2019] [Indexed: 12/22/2022]
Abstract
The number of times a cell divides before irreversibly arresting is termed replicative lifespan. Despite discovery of many chemical, dietary and genetic interventions that extend replicative lifespan, usually first discovered in budding yeast and subsequently shown to apply to metazoans, there is still little understanding of the underlying molecular mechanisms involved. One unifying theme is that most, if not all, interventions that extend replicative lifespan induce "hormesis", where a little inflicted damage makes cells more able to resist similar challenges in the future. One of the many cellular changes that occur during hormesis is a global reduction in protein synthesis, which has been linked to enhanced longevity in many organisms. Our recent study in budding yeast found that it was not the reduction in protein synthesis per se, but rather the subsequent induction of the conserved Gcn4 transcriptional regulator and its ability to induce autophagy that was responsible for extending replicative lifespan. We propose that Gcn4-dependent induction of autophagy occurring downstream of reduced global protein synthesis may be a unifying molecular mechanism for many interventions that extend replicative lifespan.
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Llabata P, Richter J, Faus I, Słomiňska-Durdasiak K, Zeh LH, Gadea J, Hauser MT. Involvement of the eIF2α Kinase GCN2 in UV-B Responses. FRONTIERS IN PLANT SCIENCE 2019; 10:1492. [PMID: 31850012 PMCID: PMC6892979 DOI: 10.3389/fpls.2019.01492] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 10/28/2019] [Indexed: 05/12/2023]
Abstract
GCN2 (general control nonrepressed 2) is a serine/threonine-protein kinase that regulates translation in response to stressors such as amino acid and purin deprivation, cold shock, wounding, cadmium, and UV-C exposure. Activated GCN2 phosphorylates the α-subunit of the eukaryotic initiation factor 2 (eIF2) leading to a drastic inhibition of protein synthesis and shifting translation to specific mRNAs. To investigate the role of GCN2 in responses to UV-B radiation its activity was analyzed through eIF2α phosphorylation assays in mutants of the specific UV-B and stress signaling pathways of Arabidopsis thaliana. EIF2α phosphorylation was detectable 30 min after UV-B exposure, independent of the UV-B photoreceptor UV RESISTANCE LOCUS8 and its downstream signaling components. GCN2 dependent phosphorylation of eIF2α was also detectable in mutants of the stress related MAP kinases, MPK3 and MPK6 and their negative regulator map kinase phosphatase1 (MKP1). Transcription of downstream components of the UV-B signaling pathway, the Chalcone synthase (CHS) was constitutively higher in gcn2-1 compared to wildtype and further increased upon UV-B while GLUTATHIONE PEROXIDASE7 (GPX7) behaved similarly to wildtype. The UVR8 independent FAD-LINKED OXIDOREDUCTASE (FADox) had a lower basal expression in gcn2-1 which was increased upon UV-B. Since high fluence rates of UV-B induce DNA damage the expression of the RAS ASSOCIATED WITH DIABETES PROTEIN51 (RAD51) was quantified before and after UV-B. While the basal expression was similar to wildtype it was significantly less induced upon UV-B in the gcn2-1 mutant. This expression pattern correlates with the finding that gcn2 mutants develop less cyclobutane pyrimidine dimers after UV-B exposure. Quantification of translation with the puromycination assay revealed that gcn2 mutants have an increased rate of translation which was also higher upon UV-B. Growth of gcn2 mutants to chronic UV-B exposure supports GCN2's role as a negative regulator of UV-B responses. The elevated resistance of gcn2 mutants towards repeated UV-B exposure points to a critical role of GCN2 in the regulation of translation upon UV-B.
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Affiliation(s)
- Paula Llabata
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), Universidad Politécnica de Valencia (UPV), Consejo Superior de Investigaciones Científicas (CSIC), Ciudad Politécnica de la Innovación (CPI), Valencia, Spain
- Institute of Applied Genetics and Cell Biology, BOKU University of Natural Resources and Life Sciences, Vienna, Austria
- Bellvitge Biomedical Research Institute IDIBELL, Barcelona, Spain
| | - Julia Richter
- Institute of Applied Genetics and Cell Biology, BOKU University of Natural Resources and Life Sciences, Vienna, Austria
| | - Isabel Faus
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), Universidad Politécnica de Valencia (UPV), Consejo Superior de Investigaciones Científicas (CSIC), Ciudad Politécnica de la Innovación (CPI), Valencia, Spain
| | - Karolina Słomiňska-Durdasiak
- Institute of Applied Genetics and Cell Biology, BOKU University of Natural Resources and Life Sciences, Vienna, Austria
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany
| | - Lukas Hubert Zeh
- Institute of Applied Genetics and Cell Biology, BOKU University of Natural Resources and Life Sciences, Vienna, Austria
| | - Jose Gadea
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), Universidad Politécnica de Valencia (UPV), Consejo Superior de Investigaciones Científicas (CSIC), Ciudad Politécnica de la Innovación (CPI), Valencia, Spain
| | - Marie-Theres Hauser
- Institute of Applied Genetics and Cell Biology, BOKU University of Natural Resources and Life Sciences, Vienna, Austria
- *Correspondence: Marie-Theres Hauser,
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Murina V, Kasari M, Takada H, Hinnu M, Saha CK, Grimshaw JW, Seki T, Reith M, Putrinš M, Tenson T, Strahl H, Hauryliuk V, Atkinson GC. ABCF ATPases Involved in Protein Synthesis, Ribosome Assembly and Antibiotic Resistance: Structural and Functional Diversification across the Tree of Life. J Mol Biol 2018; 431:3568-3590. [PMID: 30597160 PMCID: PMC6723617 DOI: 10.1016/j.jmb.2018.12.013] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 12/11/2018] [Accepted: 12/15/2018] [Indexed: 10/27/2022]
Abstract
Within the larger ABC superfamily of ATPases, ABCF family members eEF3 in Saccharomyces cerevisiae and EttA in Escherichia coli have been found to function as ribosomal translation factors. Several other ABCFs including biochemically characterized VgaA, LsaA and MsrE confer resistance to antibiotics that target the peptidyl transferase center and exit tunnel of the ribosome. However, the diversity of ABCF subfamilies, the relationships among subfamilies and the evolution of antibiotic resistance (ARE) factors from other ABCFs have not been explored. To address this, we analyzed the presence of ABCFs and their domain architectures in 4505 genomes across the tree of life. We find 45 distinct subfamilies of ABCFs that are widespread across bacterial and eukaryotic phyla, suggesting that they were present in the last common ancestor of both. Surprisingly, currently known ARE ABCFs are not confined to a distinct lineage of the ABCF family tree, suggesting that ARE can readily evolve from other ABCF functions. Our data suggest that there are a number of previously unidentified ARE ABCFs in antibiotic producers and important human pathogens. We also find that ATPase-deficient mutants of all four E. coli ABCFs (EttA, YbiT, YheS and Uup) inhibit protein synthesis, indicative of their ribosomal function, and demonstrate a genetic interaction of ABCFs Uup and YheS with translational GTPase BipA involved in assembly of the 50S ribosome subunit. Finally, we show that the ribosome-binding resistance factor VmlR from Bacillus subtilis is localized to the cytoplasm, ruling out a role in antibiotic efflux.
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Affiliation(s)
- Victoriia Murina
- Department of Molecular Biology, Umeå University, 901 87 Umeå, Sweden; Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, 901 87 Umeå, Sweden
| | - Marje Kasari
- Department of Molecular Biology, Umeå University, 901 87 Umeå, Sweden
| | - Hiraku Takada
- Department of Molecular Biology, Umeå University, 901 87 Umeå, Sweden; Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, 901 87 Umeå, Sweden
| | - Mariliis Hinnu
- University of Tartu, Institute of Technology, Nooruse 1, 50411 Tartu, Estonia
| | - Chayan Kumar Saha
- Department of Molecular Biology, Umeå University, 901 87 Umeå, Sweden
| | - James W Grimshaw
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences Newcastle University, Richardson Road, Newcastle upon Tyne, NE2 4AX, United Kingdom
| | - Takahiro Seki
- Department of Applied Chemistry and Biotechnology, Faculty of Engineering, Chiba University, 263-8522 Chiba, Japan
| | - Michael Reith
- Department of Molecular Biology, Umeå University, 901 87 Umeå, Sweden
| | - Marta Putrinš
- University of Tartu, Institute of Technology, Nooruse 1, 50411 Tartu, Estonia
| | - Tanel Tenson
- University of Tartu, Institute of Technology, Nooruse 1, 50411 Tartu, Estonia
| | - Henrik Strahl
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences Newcastle University, Richardson Road, Newcastle upon Tyne, NE2 4AX, United Kingdom
| | - Vasili Hauryliuk
- Department of Molecular Biology, Umeå University, 901 87 Umeå, Sweden; Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, 901 87 Umeå, Sweden; University of Tartu, Institute of Technology, Nooruse 1, 50411 Tartu, Estonia
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132
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Salminen A, Kaarniranta K, Kauppinen A. The role of myeloid-derived suppressor cells (MDSC) in the inflammaging process. Ageing Res Rev 2018; 48:1-10. [PMID: 30248408 DOI: 10.1016/j.arr.2018.09.001] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 08/21/2018] [Accepted: 09/10/2018] [Indexed: 01/10/2023]
Abstract
A chronic low-grade inflammation is one of the hallmarks of the aging process. This gradually augmenting inflammatory state has been termed inflammaging. Inflammaging is associated with increased myelopoiesis in the bone marrow. This myelopoiesis-biased process increases the generation not only of mature myeloid cells, e.g. monocytes, macrophages, and neutrophils, but also immature myeloid progenitors and myeloid-derived suppressor cells (MDSCs). It is known that the aging process is associated with a significant increase in the presence of MDSCs in the bone marrow, blood, spleen, and peripheral lymph nodes. Consequently, MDSCs will become recruited into inflamed tissues where they suppress acute inflammatory responses and trigger the resolution of inflammation. However, if the perpetrator cannot be eliminated, the long-term presence of MDSCs suppresses the host's immune defence and increases the susceptibility to infections and tumorigenesis. Chronic immunosuppression also impairs the clearance of waste products and dead cells, impairs energy metabolism, and disturbs tissue proteostasis. This immunosuppressive state is reminiscent of the immunosenescence observed in inflammaging. It seems that proinflammatory changes in tissues with aging stimulate the myelopoietic production of MDSCs which subsequently induces immunosenescence and maintains the chronic inflammaging process. We will briefly describe the functions of MDSCs and then examine in detail how inflammaging enhances the generation MDSCs and how MDSCs are involved in the control of immunosenescence occurring in inflammaging.
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133
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Tomek P, Gore SK, Potts CL, Print CG, Black MA, Hallermayr A, Kilian M, Sattlegger E, Ching LM. Imprinted and ancient gene: a potential mediator of cancer cell survival during tryptophan deprivation. Cell Commun Signal 2018; 16:88. [PMID: 30466445 PMCID: PMC6251197 DOI: 10.1186/s12964-018-0301-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Accepted: 11/13/2018] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Depletion of tryptophan and the accumulation of tryptophan metabolites mediated by the immunosuppressive enzyme indoleamine 2,3-dioxygenase 1 (IDO1), trigger immune cells to undergo apoptosis. However, cancer cells in the same microenvironment appear not to be affected. Mechanisms whereby cancer cells resist accelerated tryptophan degradation are not completely understood. We hypothesize that cancer cells co-opt IMPACT (the product of IMPrinted and AnCienT gene), to withstand periods of tryptophan deficiency. METHODS A range of bioinformatic techniques including correlation and gene set variation analyses was applied to genomic datasets of cancer (The Cancer Genome Atlas) and normal (Genotype Tissue Expression Project) tissues to investigate IMPACT's role in cancer. Survival of IMPACT-overexpressing GL261 glioma cells and their wild type counterparts cultured in low tryptophan media was assessed using fluorescence microscopy and MTT bio-reduction assay. Expression of the Integrated Stress Response proteins was measured using Western blotting. RESULTS We found IMPACT to be upregulated and frequently amplified in a broad range of clinical cancers relative to their non-malignant tissue counterparts. In a subset of clinical cancers, high IMPACT expression associated with decreased activity of pathways and genes involved in stress response and with increased activity of translational regulation such as the mTOR pathway. Experimental studies using the GL261 glioma line showed that cells engineered to overexpress IMPACT, gained a survival advantage over wild-type lines when cultured under limiting tryptophan concentrations. No significant difference in the expression of proteins in the Integrated Stress Response pathway was detected in tryptophan-deprived GL261 IMPACT-overexpressors compared to that in wild-type cells. IMPACT-overexpressing GL261 cells but not their wild-type counterparts, showed marked enlargement of their nuclei and cytoplasmic area when stressed by tryptophan deprivation. CONCLUSIONS The bioinformatics data together with our laboratory studies, support the hypothesis that IMPACT mediates a protective mechanism allowing cancer cells to overcome microenvironmental stresses such as tryptophan deficiency.
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Affiliation(s)
- Petr Tomek
- Auckland Cancer Society Research Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Shanti K. Gore
- Auckland Cancer Society Research Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Chloe L. Potts
- Auckland Cancer Society Research Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Cristin G. Print
- Department of Molecular Medicine & Pathology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Michael A. Black
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
| | - Ariane Hallermayr
- Auckland Cancer Society Research Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
- Medical Genetics Center (MGZ), Munich, Germany
| | - Michael Kilian
- Auckland Cancer Society Research Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
- German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Evelyn Sattlegger
- Institute of Natural and Mathematical Sciences, Massey University, Auckland, New Zealand
| | - Lai-Ming Ching
- Auckland Cancer Society Research Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
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The Leishmania donovani IMPACT-like protein possesses non-specific nuclease activity. Int J Biol Macromol 2018; 119:962-973. [DOI: 10.1016/j.ijbiomac.2018.07.175] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 07/22/2018] [Accepted: 07/27/2018] [Indexed: 12/22/2022]
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135
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Khan MF, Spurgeon SK, Yan XG. Modeling and Dynamic Behavior of eIF2 Dependent Regulatory System With Disturbances. IEEE Trans Nanobioscience 2018; 17:518-524. [PMID: 30281470 DOI: 10.1109/tnb.2018.2873027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Eukaryotic initiation factor 2 (eIF2) is a central controller of the eukaryotic translational machinery. To sustain the on-going translation activity, eIF2 cycles between its GTP and GDP bound states. However, in response to cellular stresses, the phosphorylation of eIF2 takes place, which acts as an inhibitor of the guanine nucleotide exchange factor eIF2B and switches the translation activity on physiological timescales. The main objective of this paper is to investigate the stability of the regulatory system under nominal conditions, parametric fluctuations, and structural damages. In this paper, a mathematical model of eIF2-dependent regulatory system is used to identify the stability-conferring features within the system with the help of direct and indirect methods of Lyapunov stability theory. To investigate the impact of intrinsic fluctuations and structural damages on the stability of regulatory system, the mathematical model has been linearized around feasible equilibrium point and the variation of system poles has been observed. The investigations have revealed that the regulatory model is stable and able to tolerate the intrinsic stressors but becomes unstable when particular complex is targeted to override the undesirable interaction. Our analyses indicate that, the stability is a collective property and damage in the structure of the system changes the stability of the system.
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136
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Salminen A, Kaarniranta K, Kauppinen A. The potential importance of myeloid-derived suppressor cells (MDSCs) in the pathogenesis of Alzheimer's disease. Cell Mol Life Sci 2018; 75:3099-3120. [PMID: 29779041 PMCID: PMC11105369 DOI: 10.1007/s00018-018-2844-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 04/30/2018] [Accepted: 05/16/2018] [Indexed: 02/08/2023]
Abstract
The exact cause of Alzheimer's disease (AD) is still unknown, but the deposition of amyloid-β (Aβ) plaques and chronic inflammation indicates that immune disturbances are involved in AD pathogenesis. Recent genetic studies have revealed that many candidate genes are expressed in both microglia and myeloid cells which infiltrate into the AD brains. Invading myeloid cells controls the functions of resident microglia in pathological conditions, such as AD pathology. AD is a neurologic disease with inflammatory component where the immune system is not able to eliminate the perpetrator, while, concurrently, it should prevent neuronal injuries induced by inflammation. Recent studies have indicated that AD brains are an immunosuppressive microenvironment, e.g., microglial cells are hyporesponsive to Aβ deposits and anti-inflammatory cytokines enhance Aβ deposition. Immunosuppression is a common element in pathological disorders involving chronic inflammation. Studies on cancer-associated inflammation have demonstrated that myeloid-derived suppressor cells (MDSCs) have a crucial role in the immune escape of tumor cells. Immunosuppression is not limited to tumors, since MDSCs can be recruited into chronically inflamed tissues where inflammatory mediators enhance the proliferation and activation of MDSCs. AD brains express a range of chemokines and cytokines which could recruit and expand MDSCs in inflamed AD brains and thus generate an immunosuppressive microenvironment. Several neuroinflammatory disorders, e.g., the early phase of AD pathology, have been associated with an increase in the level of circulating MDSCs. We will elucidate the immunosuppressive armament of MDSCs and present evidences in support of the crucial role of MDSCs in the pathogenesis of AD.
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Affiliation(s)
- Antero Salminen
- Department of Neurology, Institute of Clinical Medicine, University of Eastern Finland, P.O. Box 1627, 70211, Kuopio, Finland.
| | - Kai Kaarniranta
- Department of Ophthalmology, Institute of Clinical Medicine, University of Eastern Finland, P.O. Box 1627, 70211, Kuopio, Finland
- Department of Ophthalmology, Kuopio University Hospital, P.O. Box 100, 70029 KYS, Kuopio, Finland
| | - Anu Kauppinen
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, P.O. Box 1627, 70211, Kuopio, Finland
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137
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Salminen A, Kauppinen A, Kaarniranta K. Myeloid-derived suppressor cells (MDSC): an important partner in cellular/tissue senescence. Biogerontology 2018; 19:325-339. [PMID: 29959657 DOI: 10.1007/s10522-018-9762-8] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 06/27/2018] [Indexed: 01/10/2023]
Abstract
The aging process is associated with a low-grade chronic inflammation and the accumulation of senescent cells into tissues. Diverse stresses can trigger cellular senescence, a cell fate characterized by cell-cycle arrest and flat morphology. Oncogenic signaling can also induce cellular senescence which has been termed oncogene-induced senescence (OIS). Senescent cells display a pro-inflammatory phenotype which has been called the senescence-associated secretory phenotype (SASP). The secretomes associated with SASP contain colony-stimulating factors and chemokines which stimulate the generation of myeloid-derived suppressor cells (MDSC) by enhancing myelopoiesis in bone marrow and spleen. Enhanced myelopoiesis and increased level of MDSCs have been observed in bone marrow, spleen, and blood in both tumor-bearing and aged mice. Immunosuppressive MDSCs are recruited via chemotaxis into inflamed tissues where they proliferate and consequently suppress acute inflammatory reactions by inhibiting the functions of distinct components of innate and adaptive immunity. For instance, MDSCs stimulate the activity of immunosuppressive regulatory T-cells (Tregs). They also increase the expression of amino acid catabolizing enzymes and the secretion of anti-inflammatory cytokines, e.g. IL-10 and TGF-β, and reactive oxygen species (ROS). On the other hand, the accumulation of MDSCs into tissues exerts harmful effects in chronic pathological disorders, e.g. tumors and many age-related diseases, since the immunosuppression induced by MDSCs impairs the clearance of senescent and cancer cells and also disturbs the maintenance of energy metabolism and tissue proteostasis. The co-operation between senescent cells and immunosuppressive MDSCs regulates not only tumorigenesis and chronic inflammatory disorders but it also might promote inflammaging during the aging process.
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Affiliation(s)
- Antero Salminen
- Department of Neurology, Institute of Clinical Medicine, University of Eastern Finland, P.O. Box 1627, 70211, Kuopio, Finland.
| | - Anu Kauppinen
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, P.O. Box 1627, 70211, Kuopio, Finland
| | - Kai Kaarniranta
- Department of Ophthalmology, Institute of Clinical Medicine, University of Eastern Finland, P.O. Box 1627, 70211, Kuopio, Finland.,Department of Ophthalmology, Kuopio University Hospital (KYS), P.O. Box 100, 70029, Kuopio, Finland
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138
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Rodrigues LOCP, Graça RSF, Carneiro LAM. Integrated Stress Responses to Bacterial Pathogenesis Patterns. Front Immunol 2018; 9:1306. [PMID: 29930559 PMCID: PMC5999787 DOI: 10.3389/fimmu.2018.01306] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 05/25/2018] [Indexed: 12/25/2022] Open
Abstract
Activation of an appropriate innate immune response to bacterial infection is critical to limit microbial spread and generate cytokines and chemokines to instruct appropriate adaptive immune responses. Recognition of bacteria or bacterial products by pattern recognition molecules is crucial to initiate this response. However, it is increasingly clear that the context in which this recognition occurs can dictate the quality of the response and determine the outcome of an infection. The cross talk established between host and pathogen results in profound alterations on cellular homeostasis triggering specific cellular stress responses. In particular, the highly conserved integrated stress response (ISR) has been shown to shape the host response to bacterial pathogens by sensing cellular insults resulting from infection and modulating transcription of key genes, translation of new proteins and cell autonomous antimicrobial mechanisms such as autophagy. Here, we review the growing body of evidence demonstrating a role for the ISR as an integral part of the innate immune response to bacterial pathogens.
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Affiliation(s)
- Larissa O C P Rodrigues
- Laboratório de Inflamação e Imunidade, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Rodrigo S F Graça
- Laboratório de Inflamação e Imunidade, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Leticia A M Carneiro
- Laboratório de Inflamação e Imunidade, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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139
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Izquierdo Y, Kulasekaran S, Benito P, López B, Marcos R, Cascón T, Hamberg M, Castresana C. Arabidopsis nonresponding to oxylipins locus NOXY7 encodes a yeast GCN1 homolog that mediates noncanonical translation regulation and stress adaptation. PLANT, CELL & ENVIRONMENT 2018; 41:1438-1452. [PMID: 29499090 DOI: 10.1111/pce.13182] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 02/16/2018] [Accepted: 02/22/2018] [Indexed: 05/10/2023]
Abstract
Stress adaptation and translational regulation was studied using noxy7 (nonresponding to oxylipins7) from a series of Arabidopsis thaliana mutants. We identified the noxy7 mutation in At1g64790, which encodes a homolog of the yeast translational regulator General Control Nonderepressible1 (GCN1) that activates the GCN2 kinase; GCN2 in turn phosphorylates the α subunit of the translation initiation factor eIF2. This regulatory circuit is conserved in yeast and mammals, in which phosphorylated eIF2α (P-eIF2α) facilitates stress adaptation by inhibiting protein synthesis. In phenotypic and de novo protein synthesis studies with Arabidopsis mutants, we found that NOXY7/GCN1 and GCN2 mediate P-eIF2α formation and adaptation to amino acid deprivation; however, P-eIF2α formation is not linked to general protein synthesis arrest. Additional evidence suggested that NOXY7/GCN1 but not GCN2 regulates adaptation to mitochondrial dysfunction, high boron concentration, and activation of plant immunity to infection by Pseudomonas syringae pv tomato (Pst). In these responses, NOXY7/GCN1 acts with GCN20 to regulate translation in a noncanonical pathway independently of GCN2 and P-eIF2α. These results show the lesser functional relevance of GCN2 and P-eIF2α in plants relative to other eukaryotes and highlight the prominent role of NOXY7/GCN1 and GCN20 in regulation of translation and stress adaptation in plants.
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Affiliation(s)
- Yovanny Izquierdo
- Centro Nacional de Biotecnología (CNB-CSIC), Cantoblanco, Madrid, E-28049, Spain
| | - Satish Kulasekaran
- Centro Nacional de Biotecnología (CNB-CSIC), Cantoblanco, Madrid, E-28049, Spain
- School of Life Sciences, University of Warwick, Gibbett Hill Campus, Coventry, CV4 7AL, UK
| | - Pablo Benito
- Centro Nacional de Biotecnología (CNB-CSIC), Cantoblanco, Madrid, E-28049, Spain
| | - Bran López
- Centro Nacional de Biotecnología (CNB-CSIC), Cantoblanco, Madrid, E-28049, Spain
| | - Ruth Marcos
- Centro Nacional de Biotecnología (CNB-CSIC), Cantoblanco, Madrid, E-28049, Spain
| | - Tomás Cascón
- Centro Nacional de Biotecnología (CNB-CSIC), Cantoblanco, Madrid, E-28049, Spain
| | - Mats Hamberg
- Division of Physiological Chemistry II, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, S-171 77, Sweden
| | - Carmen Castresana
- Centro Nacional de Biotecnología (CNB-CSIC), Cantoblanco, Madrid, E-28049, Spain
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140
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Lim JA, Sun B, Puertollano R, Raben N. Therapeutic Benefit of Autophagy Modulation in Pompe Disease. Mol Ther 2018; 26:1783-1796. [PMID: 29804932 DOI: 10.1016/j.ymthe.2018.04.025] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 04/25/2018] [Accepted: 04/30/2018] [Indexed: 12/11/2022] Open
Abstract
The complexity of the pathogenic cascade in lysosomal storage disorders suggests that combination therapy will be needed to target various aspects of pathogenesis. The standard of care for Pompe disease (glycogen storage disease type II), a deficiency of lysosomal acid alpha glucosidase, is enzyme replacement therapy (ERT). Many patients have poor outcomes due to limited efficacy of the drug in clearing muscle glycogen stores. The resistance to therapy is linked to massive autophagic buildup in the diseased muscle. We have explored two strategies to address the problem. Genetic suppression of autophagy in muscle of knockout mice resulted in the removal of autophagic buildup, increase in muscle force, decrease in glycogen level, and near-complete clearance of lysosomal glycogen following ERT. However, this approach leads to accumulation of ubiquitinated proteins, oxidative stress, and exacerbation of muscle atrophy. Another approach involves AAV-mediated TSC knockdown in knockout muscle leading to upregulation of mTOR, inhibition of autophagy, reversal of atrophy, and efficient cellular clearance on ERT. Importantly, this approach reveals the possibility of reversing already established autophagic buildup, rather than preventing its development.
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Affiliation(s)
- Jeong-A Lim
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD, USA; Division of Medical Genetics, Department of Pediatrics, Duke University School of Medicine, Durham, NC, USA
| | - Baodong Sun
- Division of Medical Genetics, Department of Pediatrics, Duke University School of Medicine, Durham, NC, USA
| | - Rosa Puertollano
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD, USA.
| | - Nina Raben
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD, USA.
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141
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Faus I, Niñoles R, Kesari V, Llabata P, Tam E, Nebauer SG, Santiago J, Hauser MT, Gadea J. Arabidopsis ILITHYIA protein is necessary for proper chloroplast biogenesis and root development independent of eIF2α phosphorylation. JOURNAL OF PLANT PHYSIOLOGY 2018; 224-225:173-182. [PMID: 29680783 DOI: 10.1016/j.jplph.2018.04.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 04/05/2018] [Accepted: 04/08/2018] [Indexed: 05/20/2023]
Abstract
One of the main mechanisms blocking translation after stress situations is mediated by phosphorylation of the α-subunit of the eukaryotic initiation factor 2 (eIF2), performed in Arabidopsis by the protein kinase GCN2 which interacts and is activated by ILITHYIA(ILA). ILA is involved in plant immunity and its mutant lines present phenotypes not shared by the gcn2 mutants. The functional link between these two genes remains elusive in plants. In this study, we show that, although both ILA and GCN2 genes are necessary to mediate eIF2α phosphorylation upon treatments with the aromatic amino acid biosynthesis inhibitor glyphosate, their mutants develop distinct root and chloroplast phenotypes. Electron microscopy experiments reveal that ila mutants, but not gcn2, are affected in chloroplast biogenesis, explaining the macroscopic phenotype previously observed for these mutants. ila3 mutants present a complex transcriptional reprogramming affecting defense responses, photosynthesis and protein folding, among others. Double mutant analyses suggest that ILA has a distinct function which is independent of GCN2 and eIF2α phosphorylation. These results suggest that these two genes may have common but also distinct functions in Arabidopsis.
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Affiliation(s)
- I Faus
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), Universitat Politècnica de València (UPV)-Consejo Superior de Investigaciones Científicas (CSIC), Ciudad Politécnica de la Innovación (CPI), Ed. 8E, C/Ingeniero Fausto Elio s/n, 46022, Valencia, Spain.
| | - R Niñoles
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), Universitat Politècnica de València (UPV)-Consejo Superior de Investigaciones Científicas (CSIC), Ciudad Politécnica de la Innovación (CPI), Ed. 8E, C/Ingeniero Fausto Elio s/n, 46022, Valencia, Spain.
| | - V Kesari
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), Universitat Politècnica de València (UPV)-Consejo Superior de Investigaciones Científicas (CSIC), Ciudad Politécnica de la Innovación (CPI), Ed. 8E, C/Ingeniero Fausto Elio s/n, 46022, Valencia, Spain.
| | - P Llabata
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), Universitat Politècnica de València (UPV)-Consejo Superior de Investigaciones Científicas (CSIC), Ciudad Politécnica de la Innovación (CPI), Ed. 8E, C/Ingeniero Fausto Elio s/n, 46022, Valencia, Spain.
| | - E Tam
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), Universitat Politècnica de València (UPV)-Consejo Superior de Investigaciones Científicas (CSIC), Ciudad Politécnica de la Innovación (CPI), Ed. 8E, C/Ingeniero Fausto Elio s/n, 46022, Valencia, Spain.
| | - S G Nebauer
- Departamento de Producción Vegetal, Universitat Politècnica de València (UPV), Camino de Vera s/n 46022, Valencia, Spain.
| | - J Santiago
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), Universitat Politècnica de València (UPV)-Consejo Superior de Investigaciones Científicas (CSIC), Ciudad Politécnica de la Innovación (CPI), Ed. 8E, C/Ingeniero Fausto Elio s/n, 46022, Valencia, Spain.
| | - M T Hauser
- Institute of Applied Genetics and Cell Biology (IAGZ), University of Natural Resources and Life Sciences, Muthgasse 18, 1190, Vienna, Austria.
| | - J Gadea
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), Universitat Politècnica de València (UPV)-Consejo Superior de Investigaciones Científicas (CSIC), Ciudad Politécnica de la Innovación (CPI), Ed. 8E, C/Ingeniero Fausto Elio s/n, 46022, Valencia, Spain.
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142
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Eleftheriadis T, Pissas G, Liakopoulos V, Stefanidis I. IDO decreases glycolysis and glutaminolysis by activating GCN2K, while it increases fatty acid oxidation by activating AhR, thus preserving CD4+ T‑cell survival and proliferation. Int J Mol Med 2018; 42:557-568. [PMID: 29693118 DOI: 10.3892/ijmm.2018.3624] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Accepted: 03/15/2018] [Indexed: 11/05/2022] Open
Abstract
It is generally hypothesized in the literature that indoleamine 2,3‑dioxygenase (IDO), by degrading L‑tryptophan along the kynurenine pathway, suppresses CD4+ T‑cell function by inducing apoptosis, inhibiting proliferation and promoting differentiation towards a regulatory phenotype. These effects are either accompanied or directly lead to alterations in cell metabolism. The present study evaluated the pathways that govern the effect of IDO on the utilization of the three main energy sources in CD4+ T‑cells. Two‑way mixed lymphocyte reactions were performed with or without oleate and/or the IDO inhibitor 1‑methyl‑DL‑tryptophan. In addition, isolated CD4+ T‑cells cultured in an oleate‑containing medium were activated in the presence or not of the general control nonderepressible 2 kinase (GCN2K) activator tryptophanol. L‑tryptophan, glucose and free fatty acid consumption, cell proliferation, apoptosis and the levels of key proteins involved in IDO‑mediated signal transduction, and glucose, glutamine and free fatty acid utilization were assessed. The results indicate that IDO decreased glycolysis and glutaminolysis by activating GCN2K, resulting in activation of AMP‑activated protein kinase (AMPK). In parallel with AMPK activation, IDO‑induced activation of aryl hydrocarbon receptor increased the expression of all carnitine palmitoyltransferase I isoenzymes, leading ultimately to increased free fatty acid oxidation and preservation of CD4+ T‑cell survival and proliferation. Thus, contrary to what is generally hypothesized, in a normal environment containing fatty acids, the immunosuppressive effect of IDO may not be due to a decrease in CD4+ T‑cell survival and proliferation, since IDO supplies the required energy for cell survival and proliferation by increasing free fatty acid oxidation.
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Affiliation(s)
- Theodoros Eleftheriadis
- Department of Nephrology, Faculty of Medicine, University of Thessaly, 41110 Larissa, Greece
| | - Georgios Pissas
- Department of Nephrology, Faculty of Medicine, University of Thessaly, 41110 Larissa, Greece
| | - Vassilios Liakopoulos
- Department of Nephrology, Faculty of Medicine, University of Thessaly, 41110 Larissa, Greece
| | - Ioannis Stefanidis
- Department of Nephrology, Faculty of Medicine, University of Thessaly, 41110 Larissa, Greece
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143
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The integrated stress response system in cardiovascular disease. Drug Discov Today 2018; 23:920-929. [DOI: 10.1016/j.drudis.2018.02.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 01/24/2018] [Accepted: 02/22/2018] [Indexed: 12/18/2022]
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144
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Han L, Guy MP, Kon Y, Phizicky EM. Lack of 2'-O-methylation in the tRNA anticodon loop of two phylogenetically distant yeast species activates the general amino acid control pathway. PLoS Genet 2018; 14:e1007288. [PMID: 29596413 PMCID: PMC5892943 DOI: 10.1371/journal.pgen.1007288] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 04/10/2018] [Accepted: 03/05/2018] [Indexed: 01/03/2023] Open
Abstract
Modification defects in the tRNA anticodon loop often impair yeast growth and cause human disease. In the budding yeast Saccharomyces cerevisiae and the phylogenetically distant fission yeast Schizosaccharomyces pombe, trm7Δ mutants grow poorly due to lack of 2'-O-methylation of C32 and G34 in the tRNAPhe anticodon loop, and lesions in the human TRM7 homolog FTSJ1 cause non-syndromic X-linked intellectual disability (NSXLID). However, it is unclear why trm7Δ mutants grow poorly. We show here that despite the fact that S. cerevisiae trm7Δ mutants had no detectable tRNAPhe charging defect in rich media, the cells constitutively activated a robust general amino acid control (GAAC) response, acting through Gcn2, which senses uncharged tRNA. Consistent with reduced available charged tRNAPhe, the trm7Δ growth defect was suppressed by spontaneous mutations in phenylalanyl-tRNA synthetase (PheRS) or in the pol III negative regulator MAF1, and by overexpression of tRNAPhe, PheRS, or EF-1A; all of these also reduced GAAC activation. Genetic analysis also demonstrated that the trm7Δ growth defect was due to the constitutive robust GAAC activation as well as to the reduced available charged tRNAPhe. Robust GAAC activation was not observed with several other anticodon loop modification mutants. Analysis of S. pombe trm7 mutants led to similar observations. S. pombe Trm7 depletion also resulted in no observable tRNAPhe charging defect and a robust GAAC response, and suppressors mapped to PheRS and reduced GAAC activation. We speculate that GAAC activation is widely conserved in trm7 mutants in eukaryotes, including metazoans, and might play a role in FTSJ1-mediated NSXLID. The ubiquitous tRNA anticodon loop modifications have important but poorly understood functions in decoding mRNAs in the ribosome to ensure accurate and efficient protein synthesis, and their lack often impairs yeast growth and causes human disease. Here we investigate why ribose methylation of residues 32 and 34 in the anticodon loop is important. Mutations in the corresponding methyltransferase Trm7/FTSJ1 cause poor growth in the budding yeast Saccharomyces cerevisiae and near lethality in the evolutionarily distant fission yeast Schizosaccharomyces pombe, each due to reduced functional tRNAPhe. We previously showed that tRNAPhe anticodon loop modification in yeast and humans required two evolutionarily conserved Trm7 interacting proteins for Cm32 and Gm34 modification, which then stimulated G37 modification. We show here that both S. cerevisiae and S. pombe trm7Δ mutants have apparently normal tRNAPhe charging, but constitutively activate a robust general amino acid control (GAAC) response, acting through Gcn2, which senses uncharged tRNA. We also show that S. cerevisiae trm7Δ mutants grow poorly due in part to constitutive GAAC activation as well as to the uncharged tRNAPhe. We propose that TRM7 is important to prevent constitutive GAAC activation throughout eukaryotes, including metazoans, which may explain non-syndromic X-linked intellectual disability associated with human FTSJ1 mutations.
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Affiliation(s)
- Lu Han
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, NY, United States of America
| | - Michael P. Guy
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, NY, United States of America
- Department of Chemistry and Biochemistry, Northern Kentucky University, Highland Heights, KY, United States of America
| | - Yoshiko Kon
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, NY, United States of America
| | - Eric M. Phizicky
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, NY, United States of America
- * E-mail:
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145
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Cheong JE, Sun L. Targeting the IDO1/TDO2–KYN–AhR Pathway for Cancer Immunotherapy – Challenges and Opportunities. Trends Pharmacol Sci 2018; 39:307-325. [PMID: 29254698 DOI: 10.1016/j.tips.2017.11.007] [Citation(s) in RCA: 269] [Impact Index Per Article: 44.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 11/15/2017] [Accepted: 11/21/2017] [Indexed: 12/14/2022]
Affiliation(s)
- Jae Eun Cheong
- Center for Drug Discovery and Translational Research, Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Lijun Sun
- Center for Drug Discovery and Translational Research, Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
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146
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Pan T. Modifications and functional genomics of human transfer RNA. Cell Res 2018; 28:395-404. [PMID: 29463900 PMCID: PMC5939049 DOI: 10.1038/s41422-018-0013-y] [Citation(s) in RCA: 225] [Impact Index Per Article: 37.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 12/27/2017] [Indexed: 11/18/2022] Open
Abstract
Transfer RNA (tRNA) is present at tens of millions of transcripts in a human cell and is the most abundant RNA in moles among all cellular RNAs. tRNA is also the most extensively modified RNA with, on an average, 13 modifications per molecule. The primary function of tRNA as the adaptor of amino acids and the genetic code in protein synthesis is well known. tRNA modifications play multi-faceted roles in decoding and other cellular processes. The abundance, modification, and aminoacylation (charging) levels of tRNAs contribute to mRNA decoding in ways that reflect the cell type and its environment; however, how these factors work together to maximize translation efficiency remains to be understood. tRNAs also interact with many proteins not involved in translation and this may coordinate translation activity and other processes in the cell. This review focuses on the modifications and the functional genomics of human tRNA and discusses future perspectives on the explorations of human tRNA biology.
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Affiliation(s)
- Tao Pan
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, 60637, USA.
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147
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Xia X, Lei L, Qin W, Wang L, Zhang G, Hu J. GCN2 controls the cellular checkpoint: potential target for regulating inflammation. Cell Death Discov 2018. [PMID: 29531817 PMCID: PMC5841328 DOI: 10.1038/s41420-017-0022-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Affiliation(s)
- Xiaojing Xia
- 1College of Animal Science and Veterinary Medicine, Henan Institute of Science and Technology, Xinxiang, China.,2Postdoctoral Research Base, Henan Institute of Science and Technology, Xinxiang, China.,3Post-doctoral Research Station, Henan Agriculture University, Zhengzhou, China
| | - Liancheng Lei
- 4College of Veterinary Medicine, Jilin University, Changchun, China
| | - Wanhai Qin
- 5Center for Experimental and Molecular Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Lei Wang
- 1College of Animal Science and Veterinary Medicine, Henan Institute of Science and Technology, Xinxiang, China
| | - Gaiping Zhang
- 3Post-doctoral Research Station, Henan Agriculture University, Zhengzhou, China
| | - Jianhe Hu
- 1College of Animal Science and Veterinary Medicine, Henan Institute of Science and Technology, Xinxiang, China.,2Postdoctoral Research Base, Henan Institute of Science and Technology, Xinxiang, China
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148
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General amino acid control in fission yeast is regulated by a nonconserved transcription factor, with functions analogous to Gcn4/Atf4. Proc Natl Acad Sci U S A 2018; 115:E1829-E1838. [PMID: 29432178 DOI: 10.1073/pnas.1713991115] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Eukaryotes respond to amino acid starvation by enhancing the translation of mRNAs encoding b-ZIP family transcription factors (GCN4 in Saccharomyces cerevisiae and ATF4 in mammals), which launch transcriptional programs to counter this stress. This pathway involves phosphorylation of the eIF2 translation factor by Gcn2-protein kinases and is regulated by upstream ORFs (uORFs) in the GCN4/ATF4 5' leaders. Here, we present evidence that the transcription factors that mediate this response are not evolutionarily conserved. Although cells of the fission yeast Schizosaccharomyces pombe respond transcriptionally to amino acid starvation, they lack clear Gcn4 and Atf4 orthologs. We used ribosome profiling to identify mediators of this response in S. pombe, looking for transcription factors that behave like GCN4 We discovered a transcription factor (Fil1) translationally induced by amino acid starvation in a 5' leader and Gcn2-dependent manner. Like Gcn4, Fil1 is required for the transcriptional response to amino acid starvation, and Gcn4 and Fil1 regulate similar genes. Despite their similarities in regulation, function, and targets, Fil1 and Gcn4 belong to different transcription factor families (GATA and b-ZIP, respectively). Thus, the same functions are performed by nonorthologous proteins under similar regulation. These results highlight the plasticity of transcriptional networks, which maintain conserved principles with nonconserved regulators.
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149
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La maladie veino-occlusive pulmonaire. Rev Mal Respir 2018; 35:160-170. [DOI: 10.1016/j.rmr.2017.11.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 01/29/2017] [Indexed: 11/18/2022]
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150
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Gwinn DM, Lee AG, Briones-Martin-Del-Campo M, Conn CS, Simpson DR, Scott AI, Le A, Cowan TM, Ruggero D, Sweet-Cordero EA. Oncogenic KRAS Regulates Amino Acid Homeostasis and Asparagine Biosynthesis via ATF4 and Alters Sensitivity to L-Asparaginase. Cancer Cell 2018; 33:91-107.e6. [PMID: 29316436 PMCID: PMC5761662 DOI: 10.1016/j.ccell.2017.12.003] [Citation(s) in RCA: 140] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Revised: 05/25/2017] [Accepted: 12/07/2017] [Indexed: 12/19/2022]
Abstract
KRAS is a regulator of the nutrient stress response in non-small-cell lung cancer (NSCLC). Induction of the ATF4 pathway during nutrient depletion requires AKT and NRF2 downstream of KRAS. The tumor suppressor KEAP1 strongly influences the outcome of activation of this pathway during nutrient stress; loss of KEAP1 in KRAS mutant cells leads to apoptosis. Through ATF4 regulation, KRAS alters amino acid uptake and asparagine biosynthesis. The ATF4 target asparagine synthetase (ASNS) contributes to apoptotic suppression, protein biosynthesis, and mTORC1 activation. Inhibition of AKT suppressed ASNS expression and, combined with depletion of extracellular asparagine, decreased tumor growth. Therefore, KRAS is important for the cellular response to nutrient stress, and ASNS represents a promising therapeutic target in KRAS mutant NSCLC.
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Affiliation(s)
- Dana M Gwinn
- Division of Hematology and Oncology, Department of Pediatrics, Stanford University School of Medicine, Stanford, CA 94305, USA; Division of Hematology and Oncology, Department of Pediatrics, University of California San Francisco, San Francisco, CA 94158, USA
| | - Alex G Lee
- Division of Hematology and Oncology, Department of Pediatrics, Stanford University School of Medicine, Stanford, CA 94305, USA; Division of Hematology and Oncology, Department of Pediatrics, University of California San Francisco, San Francisco, CA 94158, USA
| | - Marcela Briones-Martin-Del-Campo
- Division of Hematology and Oncology, Department of Pediatrics, University of California San Francisco, San Francisco, CA 94158, USA
| | - Crystal S Conn
- School of Medicine and Department of Urology, Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94158, USA
| | - David R Simpson
- Division of Hematology and Oncology, Department of Pediatrics, Stanford University School of Medicine, Stanford, CA 94305, USA; Division of Hematology and Oncology, Department of Pediatrics, University of California San Francisco, San Francisco, CA 94158, USA
| | - Anna I Scott
- Stanford University, Department of Pathology, Stanford, CA 94305, USA
| | - Anthony Le
- Stanford University, Department of Pathology, Stanford, CA 94305, USA
| | - Tina M Cowan
- Stanford University, Department of Pathology, Stanford, CA 94305, USA
| | - Davide Ruggero
- School of Medicine and Department of Urology, Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94158, USA
| | - E Alejandro Sweet-Cordero
- Division of Hematology and Oncology, Department of Pediatrics, Stanford University School of Medicine, Stanford, CA 94305, USA; Division of Hematology and Oncology, Department of Pediatrics, University of California San Francisco, San Francisco, CA 94158, USA.
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