1
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D’Andrea G, Deroma G, Miluzio A, Biffo S. The Paradox of Ribosomal Insufficiency Coupled with Increased Cancer: Shifting the Perspective from the Cancer Cell to the Microenvironment. Cancers (Basel) 2024; 16:2392. [PMID: 39001453 PMCID: PMC11240629 DOI: 10.3390/cancers16132392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2024] [Revised: 06/25/2024] [Accepted: 06/26/2024] [Indexed: 07/16/2024] Open
Abstract
Ribosomopathies are defined as inherited diseases in which ribosomal factors are mutated. In general, they present multiorgan symptoms. In spite of the fact that in cellular models, ribosomal insufficiency leads to a reduced rate of oncogenic transformation, patients affected by ribosomopathies present a paradoxical increase in cancer incidence. Several hypotheses that explain this paradox have been formulated, mostly on the assumption that altered ribosomes in a stem cell induce compensatory changes that lead to a cancer cell. For instance, the lack of a specific ribosomal protein can lead to the generation of an abnormal ribosome, an oncoribosome, that itself leads to altered translation and increased tumorigenesis. Alternatively, the presence of ribosomal stress may induce compensatory proliferation that in turns selects the loss of tumor suppressors such as p53. However, modern views on cancer have shifted the focus from the cancer cell to the tumor microenvironment. In particular, it is evident that human lymphocytes are able to eliminate mutant cells and contribute to the maintenance of cancer-free tissues. Indeed, many tumors develop in conditions of reduced immune surveillance. In this review, we summarize the current evidence and attempt to explain cancer and ribosomopathies from the perspective of the microenvironment.
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Affiliation(s)
- Giacomo D’Andrea
- National Institute of Molecular Genetics, INGM Fondazione Romeo ed Enrica Invernizzi, 20122 Milan, Italy; (G.D.); (G.D.); (A.M.)
- Department of Biosciences, University of Milan, 20133 Milan, Italy
| | - Giorgia Deroma
- National Institute of Molecular Genetics, INGM Fondazione Romeo ed Enrica Invernizzi, 20122 Milan, Italy; (G.D.); (G.D.); (A.M.)
- Department of Biosciences, University of Milan, 20133 Milan, Italy
| | - Annarita Miluzio
- National Institute of Molecular Genetics, INGM Fondazione Romeo ed Enrica Invernizzi, 20122 Milan, Italy; (G.D.); (G.D.); (A.M.)
| | - Stefano Biffo
- National Institute of Molecular Genetics, INGM Fondazione Romeo ed Enrica Invernizzi, 20122 Milan, Italy; (G.D.); (G.D.); (A.M.)
- Department of Biosciences, University of Milan, 20133 Milan, Italy
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2
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Lane AR, Wynne ME, Faundez V. Human-specific translational control of neuronal mitochondria and excitability. Neuron 2023; 111:3901-3903. [PMID: 38128477 DOI: 10.1016/j.neuron.2023.10.031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 10/25/2023] [Accepted: 10/25/2023] [Indexed: 12/23/2023]
Abstract
How are human-specific brain bioenergetics and excitability connected? In this Neuron issue, Shen et al.1 reveal a human-specific interaction between RACK1 mRNA and FMRP. Reducing RACK1 mimics FMRP-dependent excitability and mitochondrial phenotypes, which can be reversed with mitochondrial-protective drugs. These findings suggest that FMRP-mediated translation adapts mitochondria to excitability energy demands.
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Affiliation(s)
- Alicia R Lane
- Department of Cell Biology, Emory University, Atlanta, GA 30322, USA
| | - Meghan E Wynne
- Department of Cell Biology, Emory University, Atlanta, GA 30322, USA
| | - Victor Faundez
- Department of Cell Biology, Emory University, Atlanta, GA 30322, USA.
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3
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Sun Y, Li M, Geng J, Meng S, Tu R, Zhuang Y, Sun M, Rui M, Ou M, Xing G, Johnson TK, Xie W. Neuroligin 2 governs synaptic morphology and function through RACK1-cofilin signaling in Drosophila. Commun Biol 2023; 6:1056. [PMID: 37853189 PMCID: PMC10584876 DOI: 10.1038/s42003-023-05428-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Accepted: 10/06/2023] [Indexed: 10/20/2023] Open
Abstract
Neuroligins are transmembrane cell adhesion proteins well-known for their genetic links to autism spectrum disorders. Neuroligins can function by regulating the actin cytoskeleton, however the factors and mechanisms involved are still largely unknown. Here, using the Drosophila neuromuscular junction as a model, we reveal that F-Actin assembly at the Drosophila NMJ is controlled through Cofilin signaling mediated by an interaction between DNlg2 and RACK1, factors not previously known to work together. The deletion of DNlg2 displays disrupted RACK1-Cofilin signaling pathway with diminished actin cytoskeleton proteo-stasis at the terminal of the NMJ, aberrant NMJ structure, reduced synaptic transmission, and abnormal locomotion at the third-instar larval stage. Overexpression of wildtype and activated Cofilin in muscles are sufficient to rescue the morphological and physiological defects in dnlg2 mutants, while inactivated Cofilin is not. Since the DNlg2 paralog DNlg1 is known to regulate F-actin assembly mainly via a specific interaction with WAVE complex, our present work suggests that the orchestration of F-actin by Neuroligins is a diverse and complex process critical for neural connectivity.
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Affiliation(s)
- Yichen Sun
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, 210096, China
- School of Biological Sciences, Monash University, Clayton, VIC, 3800, Australia
| | - Moyi Li
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, 210096, China.
- Jiangsu Co-innovation Center of Neuroregeneration, Nantong University, Nantong, 226001, China.
| | - Junhua Geng
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, 210096, China
| | - Sibie Meng
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, 210096, China
| | - Renjun Tu
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, 210096, China
| | - Yan Zhuang
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, 210096, China
| | - Mingkuan Sun
- The Key Laboratory of Modern Toxicology, Ministry of Education, School of Public Health, Nanjing Medical University, Nanjing, 211166, China
| | - Menglong Rui
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, 210096, China
| | - Mengzhu Ou
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, 210096, China
| | - Guangling Xing
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, 210096, China
| | - Travis K Johnson
- School of Biological Sciences, Monash University, Clayton, VIC, 3800, Australia
- Department of Biochemistry and Chemistry, and La Trobe Institute for Molecular Science, La Trobe University, Bundoora, VIC, 3086, Australia
| | - Wei Xie
- School of Life Science and Technology, The Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, 210096, China.
- Jiangsu Co-innovation Center of Neuroregeneration, Nantong University, Nantong, 226001, China.
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4
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Fakih Z, Plourde MB, Germain H. Differential Participation of Plant Ribosomal Proteins from the Small Ribosomal Subunit in Protein Translation under Stress. Biomolecules 2023; 13:1160. [PMID: 37509195 PMCID: PMC10377644 DOI: 10.3390/biom13071160] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 07/12/2023] [Accepted: 07/13/2023] [Indexed: 07/30/2023] Open
Abstract
Upon exposure to biotic and abiotic stress, plants have developed strategies to adapt to the challenges imposed by these unfavorable conditions. The energetically demanding translation process is one of the main elements regulated to reduce energy consumption and to selectively synthesize proteins involved in the establishment of an adequate response. Emerging data have shown that ribosomes remodel to adapt to stresses. In Arabidopsis thaliana, ribosomes consist of approximately eighty-one distinct ribosomal proteins (RPs), each of which is encoded by two to seven genes. Recent research has revealed that a mutation in a given single RP in plants can not only affect the functions of the RP itself but can also influence the properties of the ribosome, which could bring about changes in the translation to varying degrees. However, a pending question is whether some RPs enable ribosomes to preferentially translate specific mRNAs. To reveal the role of ribosomal proteins from the small subunit (RPS) in a specific translation, we developed a novel approach to visualize the effect of RPS silencing on the translation of a reporter mRNA (GFP) combined to the 5'UTR of different housekeeping and defense genes. The silencing of genes encoding for NbRPSaA, NbRPS5A, and NbRPS24A in Nicotiana benthamiana decreased the translation of defense genes. The NbRACK1A-silenced plant showed compromised translations of specific antioxidant enzymes. However, the translations of all tested genes were affected in NbRPS27D-silenced plants. These findings suggest that some RPS may be potentially involved in the control of protein translation.
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Affiliation(s)
- Zainab Fakih
- Department of Chemistry, Biochemistry and Physics and Groupe de Recherche en Biologie Végétale, Université du Québec à Trois-Rivières, Trois-Rivières, QC G9A 5H9, Canada
| | - Mélodie B Plourde
- Department of Chemistry, Biochemistry and Physics and Groupe de Recherche en Biologie Végétale, Université du Québec à Trois-Rivières, Trois-Rivières, QC G9A 5H9, Canada
| | - Hugo Germain
- Department of Chemistry, Biochemistry and Physics and Groupe de Recherche en Biologie Végétale, Université du Québec à Trois-Rivières, Trois-Rivières, QC G9A 5H9, Canada
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5
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Chvalova V, Venkadasubramanian V, Klimova Z, Vojtova J, Benada O, Vanatko O, Vomastek T, Grousl T. Characterization of RACK1-depleted mammalian cells by a palette of microscopy approaches reveals defects in cell cycle progression and polarity establishment. Exp Cell Res 2023:113695. [PMID: 37393981 DOI: 10.1016/j.yexcr.2023.113695] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 06/08/2023] [Accepted: 06/22/2023] [Indexed: 07/04/2023]
Abstract
The Receptor for Activated C Kinase 1 (RACK1) is an evolutionarily conserved scaffold protein involved in the regulation of numerous cellular processes. Here, we used CRISPR/Cas9 and siRNA to reduce the expression of RACK1 in Madin-Darby Canine Kidney (MDCK) epithelial cells and Rat2 fibroblasts, respectively. RACK1-depleted cells were examined using coherence-controlled holographic microscopy, immunofluorescence, and electron microscopy. RACK1 depletion resulted in decreased cell proliferation, increased cell area and perimeter, and in the appearance of large binucleated cells suggesting a defect in the cell cycle progression. Our results show that the depletion of RACK1 has a pleiotropic effect on both epithelial and mesenchymal cell lines and support its essential role in mammalian cells.
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Affiliation(s)
- Vera Chvalova
- Laboratory of Cell Signalling, Institute of Microbiology of the Czech Academy of Sciences, Videnska 1083, 142 00, Prague, Czech Republic; Faculty of Science, Charles University, 128 00, Prague, Czech Republic
| | - Vignesh Venkadasubramanian
- Laboratory of Cell Signalling, Institute of Microbiology of the Czech Academy of Sciences, Videnska 1083, 142 00, Prague, Czech Republic; Faculty of Science, Charles University, 128 00, Prague, Czech Republic
| | - Zuzana Klimova
- Laboratory of Cell Signalling, Institute of Microbiology of the Czech Academy of Sciences, Videnska 1083, 142 00, Prague, Czech Republic
| | - Jana Vojtova
- Laboratory of Regulation of Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, 142 00, Prague, Czech Republic
| | - Oldrich Benada
- Laboratory of Molecular Structure Characterization, Institute of Microbiology of the Czech Academy of Sciences, 142 00, Prague, Czech Republic
| | - Ondrej Vanatko
- Department of Cellular Neurophysiology, Institute of Experimental Medicine of the Czech Academy of Sciences, 142 00, Prague, Czech Republic; Second Faculty of Medicine, Charles University, 150 06, Prague, Czech Republic
| | - Tomas Vomastek
- Laboratory of Cell Signalling, Institute of Microbiology of the Czech Academy of Sciences, Videnska 1083, 142 00, Prague, Czech Republic
| | - Tomas Grousl
- Laboratory of Cell Signalling, Institute of Microbiology of the Czech Academy of Sciences, Videnska 1083, 142 00, Prague, Czech Republic.
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6
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Wu Z, Hu G, Gong T, Hu Q, Hong L, Zhang Y, Ao Z. RACK1 may participate in placental development at mid-gestation via regulating trophoblast cell proliferation and migration in pigs. Mol Reprod Dev 2023; 90:248-259. [PMID: 36916007 DOI: 10.1002/mrd.23680] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2022] [Revised: 02/22/2023] [Accepted: 02/24/2023] [Indexed: 03/15/2023]
Abstract
Intrauterine growth restriction (IUGR) is a severe complication in swine production. Placental insufficiency is responsible for inadequate fetal growth, but the specific etiology of placental dysfunction-induced IUGR in pigs remains poorly understood. In this work, placenta samples supplying the lightest weight (LW) and mean weight (MW) pig fetuses in the litter at Day 65 (D65) of gestation were collected, and the relationship between fetal growth and placental morphologies and functions was investigated using histomorphological analysis, RNA sequencing, quantitative polymerase chain reaction, and in vitro experiment in LW and MW placentas. Results showed that the folded structure of the epithelial bilayer of LW placentas followed a poor and incomplete development compared with that of MW placentas. A total of 654 differentially expressed genes (DEGs) were screened out between the LW and MW placentas, and the gene encodes receptor for activated C kinase 1 (RACK1) was found to be downregulated in LW placentas. The DEGs were mainly enriched in translation, ribosome, protein synthesis, and mammalian target of rapamycin (mTOR) signaling pathway according to gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. In vitro experiments indicated that the decreased RACK1 in LW placentas may be involved in abnormal development of placental folds (PFs) by inhibiting the proliferation and migration of porcine trophoblast cells. Taken together, these results revealed that RACK1 may be a vital regulator in the development of PFs via regulating trophoblast cell proliferation and migration in pigs.
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Affiliation(s)
- Zhimin Wu
- Key Laboratory of Animal Genetics, Breeding and Reproduction in the Plateau Mountainous Region, Ministry of Education, College of Animal Science, Guizhou University, Guiyang, China.,Guizhou Provincial Key Laboratory of Animal Genetics, Breeding and Reproduction, College of Animal Science, Guizhou University, Guiyang, China
| | - Guangling Hu
- Key Laboratory of Animal Genetics, Breeding and Reproduction in the Plateau Mountainous Region, Ministry of Education, College of Animal Science, Guizhou University, Guiyang, China.,Guizhou Provincial Key Laboratory of Animal Genetics, Breeding and Reproduction, College of Animal Science, Guizhou University, Guiyang, China
| | - Ting Gong
- Key Laboratory of Animal Genetics, Breeding and Reproduction in the Plateau Mountainous Region, Ministry of Education, College of Animal Science, Guizhou University, Guiyang, China.,Guizhou Provincial Key Laboratory of Animal Genetics, Breeding and Reproduction, College of Animal Science, Guizhou University, Guiyang, China
| | - Qun Hu
- National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Linjun Hong
- National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Yiyu Zhang
- Key Laboratory of Animal Genetics, Breeding and Reproduction in the Plateau Mountainous Region, Ministry of Education, College of Animal Science, Guizhou University, Guiyang, China.,Guizhou Provincial Key Laboratory of Animal Genetics, Breeding and Reproduction, College of Animal Science, Guizhou University, Guiyang, China
| | - Zheng Ao
- Key Laboratory of Animal Genetics, Breeding and Reproduction in the Plateau Mountainous Region, Ministry of Education, College of Animal Science, Guizhou University, Guiyang, China.,Guizhou Provincial Key Laboratory of Animal Genetics, Breeding and Reproduction, College of Animal Science, Guizhou University, Guiyang, China
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7
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Translational Control of Metabolism and Cell Cycle Progression in Hepatocellular Carcinoma. Int J Mol Sci 2023; 24:ijms24054885. [PMID: 36902316 PMCID: PMC10002961 DOI: 10.3390/ijms24054885] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 02/27/2023] [Accepted: 03/01/2023] [Indexed: 03/06/2023] Open
Abstract
The liver is a metabolic hub characterized by high levels of protein synthesis. Eukaryotic initiation factors, eIFs, control the first phase of translation, initiation. Initiation factors are essential for tumor progression and, since they regulate the translation of specific mRNAs downstream of oncogenic signaling cascades, may be druggable. In this review, we address the issue of whether the massive translational machinery of liver cells contributes to liver pathology and to the progression of hepatocellular carcinoma (HCC); it represents a valuable biomarker and druggable target. First, we observe that the common markers of HCC cells, such as phosphorylated ribosomal protein S6, belong to the ribosomal and translational apparatus. This fact is in agreement with observations that demonstrate a huge amplification of the ribosomal machinery during the progression to HCC. Some translation factors, such as eIF4E and eIF6, are then harnessed by oncogenic signaling. In particular, the action of eIF4E and eIF6 is particularly important in HCC when driven by fatty liver pathologies. Indeed, both eIF4E and eIF6 amplify at the translational level the production and accumulation of fatty acids. As it is evident that abnormal levels of these factors drive cancer, we discuss their therapeutic value.
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8
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Knight JRP, Proud CG, Mallucci G, von der Haar T, Smales CM, Willis AE, Sansom OJ. Eukaryotic Elongation Factor 2 Kinase Activity Is Required for the Phenotypes of the Rpl24 Bst Mouse. J Invest Dermatol 2022; 142:3346-3348.e1. [PMID: 35850210 PMCID: PMC9708116 DOI: 10.1016/j.jid.2022.06.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 06/22/2022] [Accepted: 06/22/2022] [Indexed: 01/27/2023]
Affiliation(s)
- John R P Knight
- Beatson Institute, Cancer Research UK, Glasgow, United Kingdom; Division of Cancer Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom
| | - Christopher G Proud
- Lifelong Health, South Australian Health and Medical Research Institute, Adelaide, Australia; Department of Biological Sciences, University of Adelaide, Adelaide, Australia
| | - Giovanna Mallucci
- UK Dementia Research Institute at The University of Cambridge, Cambridge, United Kingdom; Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom
| | | | - C Mark Smales
- School of Biosciences, University of Kent, Canterbury, United Kingdom
| | - Anne E Willis
- MRC Toxicology Unit, University of Cambridge, Cambridge, United Kingdom
| | - Owen J Sansom
- Beatson Institute, Cancer Research UK, Glasgow, United Kingdom; Institute of Cancer Sciences, University of Glasgow, Glasgow, United Kingdom.
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9
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Catalani E, Zecchini S, Giovarelli M, Cherubini A, Del Quondam S, Brunetti K, Silvestri F, Roux-Biejat P, Napoli A, Casati SR, Ceci M, Romano N, Bongiorni S, Prantera G, Clementi E, Perrotta C, De Palma C, Cervia D. RACK1 is evolutionary conserved in satellite stem cell activation and adult skeletal muscle regeneration. Cell Death Dis 2022; 8:459. [PMID: 36396939 PMCID: PMC9672362 DOI: 10.1038/s41420-022-01250-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 11/03/2022] [Accepted: 11/07/2022] [Indexed: 11/19/2022]
Abstract
Skeletal muscle growth and regeneration involves the activity of resident adult stem cells, namely satellite cells (SC). Despite numerous mechanisms have been described, different signals are emerging as relevant in SC homeostasis. Here we demonstrated that the Receptor for Activated C-Kinase 1 (RACK1) is important in SC function. RACK1 was expressed transiently in the skeletal muscle of post-natal mice, being abundant in the early phase of muscle growth and almost disappearing in adult mature fibers. The presence of RACK1 in interstitial SC was also detected. After acute injury in muscle of both mouse and the fruit fly Drosophila melanogaster (used as alternative in vivo model) we found that RACK1 accumulated in regenerating fibers while it declined with the progression of repair process. To note, RACK1 also localized in the active SC that populate recovering tissue. The dynamics of RACK1 levels in isolated adult SC of mice, i.e., progressively high during differentiation and low compared to proliferating conditions, and RACK1 silencing indicated that RACK1 promotes both the formation of myotubes and the accretion of nascent myotubes. In Drosophila with depleted RACK1 in all muscle cells or, specifically, in SC lineage we observed a delayed recovery of skeletal muscle after physical damage as well as the low presence of active SC in the wound area. Our results also suggest the coupling of RACK1 to muscle unfolded protein response during SC activation. Collectively, we provided the first evidence that transient levels of the evolutionarily conserved factor RACK1 are critical for adult SC activation and proper skeletal muscle regeneration, favoring the efficient progression of SC from a committed to a fully differentiated state.
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10
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Qin W, Zhang T, Ge M, Zhou H, Xu Y, Mu R, Huang C, Liu D, Huang B, Wang Q, Kong Q, Kong Q, Li F, Xiong W. Hepatic RACK1 deletion disturbs lipid and glucose homeostasis independently of insulin resistance. J Endocrinol 2022; 254:137-151. [PMID: 35608066 DOI: 10.1530/joe-22-0076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 05/23/2022] [Indexed: 11/08/2022]
Abstract
Receptor for activated C kinase 1 (RACK1) is a versatile protein involved in multiple biological processes. In a previous study by Zhao et al., hepatic RACK1 deletion in mice led to an inhibition of autophagy, blocked autophagy-dependent lipolysis, and caused steatosis. Using the same mouse model (RACK1hep-/-), we revealed new roles of RACK1 in maintaining bile acid homeostasis and hepatic glucose uptake, which further affected circulatory lipid and glucose levels. To be specific, even under hepatic steatosis, the plasma lipids were generally reduced in RACK1hep-/- mouse, which was due to the suppression of intestinal lipid absorption. Accordingly, a decrease in total bile acid level was found in RACK1hep-/- livers, gallbladders, and small intestine tissues, and specific decrease of 12-hydroxylated bile acids was detected by liquid chromatography-mass spectrometry. Consistently, reduced expression of CYP8B1 was found. A decrease in hepatic glycogen storage was also observed, which might be due to the inhibited glucose uptake by GLUT2 insufficiency. Interestingly, RACK1-KO-inducing hepatic steatosis did not raise insulin resistance (IR) nor IR-inducing factors like endoplasmic reticulum stress and inflammation. In summary, this study uncovers that hepatic RACK1 might be required in maintaining bile acid homeostasis and glucose uptake in hepatocytes. This study also provides an additional case of hepatic steatosis disassociation with insulin resistance.
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Affiliation(s)
- Wanying Qin
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, People's Republic of China
- University of the Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Ting Zhang
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, People's Republic of China
- University of the Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Mingxia Ge
- University of the Chinese Academy of Sciences, Beijing, People's Republic of China
- State Key Laboratory of Genetic Resources and Evolution/Key Laboratory of Healthy Aging Research of Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, People's Republic of China
| | - Huimin Zhou
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, People's Republic of China
| | - Yuhui Xu
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, People's Republic of China
| | - Rongfang Mu
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, People's Republic of China
| | - Chaoguang Huang
- Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, Yunnan Provincial Center for Research & Development of Natural Products, School of Chemical Science and Technology, Yunnan University, Kunming, People's Republic of China
| | - Daowei Liu
- Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, Yunnan Provincial Center for Research & Development of Natural Products, School of Chemical Science and Technology, Yunnan University, Kunming, People's Republic of China
| | - Bangrui Huang
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, People's Republic of China
- University of the Chinese Academy of Sciences, Beijing, People's Republic of China
- Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, Yunnan Provincial Center for Research & Development of Natural Products, School of Chemical Science and Technology, Yunnan University, Kunming, People's Republic of China
| | - Qian Wang
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, People's Republic of China
- Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, Yunnan Provincial Center for Research & Development of Natural Products, School of Chemical Science and Technology, Yunnan University, Kunming, People's Republic of China
| | - Qinghua Kong
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, People's Republic of China
| | - Qingpeng Kong
- State Key Laboratory of Genetic Resources and Evolution/Key Laboratory of Healthy Aging Research of Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, People's Republic of China
| | - Fei Li
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, People's Republic of China
- Laboratory of Metabolomics and Drug-induced Liver Injury, Sichuan University-Oxford University Huaxi Gastrointestinal Cancer Centre, Frontiers Science Center for Disease-related Molecular Network, West China Hospital, Sichuan University, Chengdu, People's Republic of China
| | - Wenyong Xiong
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, People's Republic of China
- Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, Yunnan Provincial Center for Research & Development of Natural Products, School of Chemical Science and Technology, Yunnan University, Kunming, People's Republic of China
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11
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Keen AN, Payne LA, Mehta V, Rice A, Simpson LJ, Pang KL, del Rio Hernandez A, Reader JS, Tzima E. Eukaryotic initiation factor 6 regulates mechanical responses in endothelial cells. J Cell Biol 2022; 221:e202005213. [PMID: 35024764 PMCID: PMC8763864 DOI: 10.1083/jcb.202005213] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 10/11/2021] [Accepted: 12/08/2021] [Indexed: 12/22/2022] Open
Abstract
The repertoire of extratranslational functions of components of the protein synthesis apparatus is expanding to include control of key cell signaling networks. However, very little is known about noncanonical functions of members of the protein synthesis machinery in regulating cellular mechanics. We demonstrate that the eukaryotic initiation factor 6 (eIF6) modulates cellular mechanobiology. eIF6-depleted endothelial cells, under basal conditions, exhibit unchanged nascent protein synthesis, polysome profiles, and cytoskeleton protein expression, with minimal effects on ribosomal biogenesis. In contrast, using traction force and atomic force microscopy, we show that loss of eIF6 leads to reduced stiffness and force generation accompanied by cytoskeletal and focal adhesion defects. Mechanistically, we show that eIF6 is required for the correct spatial mechanoactivation of ERK1/2 via stabilization of an eIF6-RACK1-ERK1/2-FAK mechanocomplex, which is necessary for force-induced remodeling. These results reveal an extratranslational function for eIF6 and a novel paradigm for how mechanotransduction, the cellular cytoskeleton, and protein translation constituents are linked.
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Affiliation(s)
- Adam N. Keen
- Radcliffe Department of Medicine, University of Oxford, Oxford, UK
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Luke A. Payne
- Radcliffe Department of Medicine, University of Oxford, Oxford, UK
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Vedanta Mehta
- Radcliffe Department of Medicine, University of Oxford, Oxford, UK
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Alistair Rice
- Cellular and Molecular Biomechanics Laboratory, Department of Bioengineering, Imperial College London, London, UK
| | - Lisa J. Simpson
- Radcliffe Department of Medicine, University of Oxford, Oxford, UK
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Kar Lai Pang
- Radcliffe Department of Medicine, University of Oxford, Oxford, UK
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Armando del Rio Hernandez
- Cellular and Molecular Biomechanics Laboratory, Department of Bioengineering, Imperial College London, London, UK
| | - John S. Reader
- Radcliffe Department of Medicine, University of Oxford, Oxford, UK
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Ellie Tzima
- Radcliffe Department of Medicine, University of Oxford, Oxford, UK
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
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12
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Roles of RACK1 in centrosome regulation and carcinogenesis. Cell Signal 2021; 90:110207. [PMID: 34843916 DOI: 10.1016/j.cellsig.2021.110207] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 11/23/2021] [Accepted: 11/24/2021] [Indexed: 11/22/2022]
Abstract
Receptor for activated C kinase 1 (RACK1) regulates various cellular functions and signaling pathways by interacting with different proteins. Recently, we showed that RACK1 interacts with breast cancer gene 1 (BRCA1), which regulates centrosome duplication. RACK1 localizes to centrosomes and spindle poles and is involved in the proper centrosomal localization of BRCA1. The interaction between RACK1 and BRCA1 is critical for the regulation of centrosome number. In addition, RACK1 contributes to centriole duplication by regulating polo-like kinase 1 (PLK1) activity in S phase. RACK1 binds directly to PLK1 and Aurora A, promoting the phosphorylation of PLK1 and activating the Aurora A/PLK1 signaling axis. Overexpression of RACK1 causes centrosome amplification, especially in mammary gland epithelial cells, inducing overactivation of PLK1 followed by premature centriole disengagement and centriole re-duplication. Other proteins, including hypoxia-inducible factor α, von Hippel-Lindau protein, heat-shock protein 90, β-catenin, and glycogen synthase kinase-3β, interact with RACK1 and play roles in centrosome regulation. In this review, we focus on the roles and underlying molecular mechanisms of RACK1 in centrosome regulation mediated by its interaction with different proteins and the modulation of their functions.
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13
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Ling J, Tiwari M, Chen Y, Sen GL. RACK1 Prevents the Premature Differentiation of Epidermal Progenitor Cells by Inhibiting IRF6 Expression. J Invest Dermatol 2021; 142:1499-1502.e4. [PMID: 34742704 DOI: 10.1016/j.jid.2021.10.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 09/29/2021] [Accepted: 10/18/2021] [Indexed: 11/16/2022]
Affiliation(s)
- Ji Ling
- Department of Dermatology, Department of Cellular and Molecular Medicine, UCSD Stem Cell Program, University of California, San Diego, La Jolla, CA 92093-0869
| | - Manisha Tiwari
- Department of Dermatology, Department of Cellular and Molecular Medicine, UCSD Stem Cell Program, University of California, San Diego, La Jolla, CA 92093-0869
| | - Yifang Chen
- Department of Dermatology, Department of Cellular and Molecular Medicine, UCSD Stem Cell Program, University of California, San Diego, La Jolla, CA 92093-0869
| | - George L Sen
- Department of Dermatology, Department of Cellular and Molecular Medicine, UCSD Stem Cell Program, University of California, San Diego, La Jolla, CA 92093-0869.
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14
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Schmitt K, Kraft AA, Valerius O. A Multi-Perspective Proximity View on the Dynamic Head Region of the Ribosomal 40S Subunit. Int J Mol Sci 2021; 22:ijms222111653. [PMID: 34769086 PMCID: PMC8583833 DOI: 10.3390/ijms222111653] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 10/23/2021] [Accepted: 10/25/2021] [Indexed: 11/25/2022] Open
Abstract
A comparison of overlapping proximity captures at the head region of the ribosomal 40S subunit (hr40S) in Saccharomyces cerevisiae from four adjacent perspectives, namely Asc1/RACK1, Rps2/uS5, Rps3/uS3, and Rps20/uS10, corroborates dynamic co-localization of proteins that control activity and fate of both ribosomes and mRNA. Co-locating factors that associate with the hr40S are involved in (i) (de)ubiquitination of ribosomal proteins (Hel2, Bre5-Ubp3), (ii) clamping of inactive ribosomal subunits (Stm1), (iii) mRNA surveillance and vesicular transport (Smy2, Syh1), (iv) degradation of mRNA (endo- and exonucleases Ypl199c and Xrn1, respectively), (v) autophagy (Psp2, Vps30, Ykt6), and (vi) kinase signaling (Ste20). Additionally, they must be harmonized with translation initiation factors (eIF3, cap-binding protein Cdc33, eIF2A) and mRNA-binding/ribosome-charging proteins (Scp160, Sro9). The Rps/uS-BioID perspectives revealed substantial Asc1/RACK1-dependent hr40S configuration indicating a function of the β-propeller in context-specific spatial organization of this microenvironment. Toward resolving context-specific constellations, a Split-TurboID analysis emphasized the ubiquitin-associated factors Def1 and Lsm12 as neighbors of Bre5 at hr40S. These shuttling proteins indicate a common regulatory axis for the fate of polymerizing machineries for the biosynthesis of proteins in the cytoplasm and RNA/DNA in the nucleus.
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15
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The role of RNA-binding and ribosomal proteins as specific RNA translation regulators in cellular differentiation and carcinogenesis. Biochim Biophys Acta Mol Basis Dis 2020; 1867:166046. [PMID: 33383105 DOI: 10.1016/j.bbadis.2020.166046] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 12/03/2020] [Accepted: 12/10/2020] [Indexed: 02/07/2023]
Abstract
Tight control of mRNA expression is required for cell differentiation; imbalanced regulation may lead to developmental disorders and cancer. The activity of the translational machinery (including ribosomes and translation factors) regulates the rate (slow or fast) of translation of encoded proteins, and the quality of these proteins highly depends on which mRNAs are available for translation. Specific RNA-binding and ribosomal proteins seem to play a key role in controlling gene expression to determine the differentiation fate of the cell. This demonstrates the important role of RNA-binding proteins, specific ribosome-binding proteins and microRNAs as key molecules in controlling the specific proteins required for the differentiation or dedifferentiation of cells. This delicate balance between specific proteins (in terms of quality and availability) and post-translational modifications occurring in the cytoplasm is crucial for cell differentiation, dedifferentiation and oncogenic potential. In this review, we report how defects in the regulation of mRNA translation can be dependent on specific proteins and can induce an imbalance between differentiation and dedifferentiation in cell fate determination.
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16
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Curnow AC, Gonsalez SR, Gogulamudi VR, Visniauskas B, Simon EE, Gonzalez AA, Majid DSA, Lara LS, Prieto MC. Low Nitric Oxide Bioavailability Increases Renin Production in the Collecting Duct. Front Physiol 2020; 11:559341. [PMID: 33281610 PMCID: PMC7705222 DOI: 10.3389/fphys.2020.559341] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 10/21/2020] [Indexed: 12/14/2022] Open
Abstract
In the kidney, the stimulation of renin production by the collecting duct (CD-renin) contributes to the development of hypertension. The CD is a major nephron segment for the synthesis of nitric oxide (NO), and low NO bioavailability in the renal medulla is associated with hypertension. However, it is unknown whether NO regulates renin production in the CD. To test the hypothesis that low intrarenal NO levels stimulate the production of CD-renin, we first examined renin expression in the distal nephron segments of CD-eNOS deficient mice. In these mice, specific CD-renin immunoreactivity was increased compared to wild-type littermates; however, juxtaglomerular (JG) renin was not altered. To further assess the intracellular mechanisms involved, we then treated M-1 cells with either 1 mM L-NAME (L-arginine analog), an inhibitor of NO synthase activity, or 1 mM NONOate, a NO donor. Both treatments increased intracellular renin protein levels in M-1 cells. However, only the inhibition of NOS with L-NAME stimulated renin synthesis and secretion as reflected by the increase in Ren1C transcript and renin protein levels in the extracellular media, respectively. In addition, NONOate induced a fast mobilization of cGMP and intracellular renin accumulation. These response was partially prevented by guanylyl cyclase inhibition with ODQ (1H-[1,2,4] oxadiazolo[4,3-a]quinoxalin-1]. Accumulation of intracellular renin was blocked by protein kinase G (PKG) and protein kinase C (PKC) inhibitors. Our data indicate that low NO bioavailability increases CD-renin synthesis and secretion, which may contribute to the activation of intrarenal renin angiotensin system.
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Affiliation(s)
- Andrew C. Curnow
- Department of Physiology, Tulane University School of Medicine, New Orleans, LA, United States
| | - Sabrina R. Gonsalez
- Department of Physiology, Tulane University School of Medicine, New Orleans, LA, United States
- Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | | | - Bruna Visniauskas
- Department of Physiology, Tulane University School of Medicine, New Orleans, LA, United States
| | - Eric E. Simon
- Department of Medicine, Tulane University School of Medicine, New Orleans, LA, United States
| | - Alexis A. Gonzalez
- Instituto de Química, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
| | - Dewan S. A. Majid
- Department of Physiology, Tulane University School of Medicine, New Orleans, LA, United States
- Hypertension and Renal Center of Excellence, Tulane University School of Medicine, New Orleans, LA, United States
| | - Lucienne S. Lara
- Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Minolfa C. Prieto
- Department of Physiology, Tulane University School of Medicine, New Orleans, LA, United States
- Hypertension and Renal Center of Excellence, Tulane University School of Medicine, New Orleans, LA, United States
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17
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Duan Y, Zhang L, Angosto-Bazarra D, Pelegrín P, Núñez G, He Y. RACK1 Mediates NLRP3 Inflammasome Activation by Promoting NLRP3 Active Conformation and Inflammasome Assembly. Cell Rep 2020; 33:108405. [PMID: 33207200 DOI: 10.1016/j.celrep.2020.108405] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 09/11/2020] [Accepted: 10/26/2020] [Indexed: 10/23/2022] Open
Abstract
The NLRP3 inflammasome, a critical component of the innate immune system, induces caspase-1 activation and interleukin (IL)-1β maturation in response to microbial infection and cellular damage. However, aberrant activation of the NLRP3 inflammasome contributes to the pathogenesis of several inflammatory disorders, including cryopyrin-associated periodic syndromes, Alzheimer's disease, type 2 diabetes, and atherosclerosis. Here, we identify the receptor for activated protein C kinase 1 (RACK1) as a component of the NLRP3 complexes in macrophages. RACK1 interacts with NLRP3 and NEK7 but not ASC. Suppression of RACK1 expression abrogates caspase-1 activation and IL-1β release in response to NLRP3- but not NLRC4- or AIM2-activating stimuli. This RACK1 function is independent of its ribosomal binding activity. Mechanistically, RACK1 promotes the active conformation of NLRP3 induced by activating stimuli and subsequent inflammasome assembly. These results demonstrate that RACK1 is a critical mediator for NLRP3 inflammasome activation.
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Affiliation(s)
- Yanhui Duan
- Department of Biochemistry, Microbiology and Immunology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Lingzhi Zhang
- Department of Pathology and Rogel Cancer Center, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Diego Angosto-Bazarra
- Instituto Murciano de Investigación Biosanitaria IMIB-Arrixaca, Hospital Clínico Universitario Virgen de la Arrixaca, Murcia, Spain
| | - Pablo Pelegrín
- Instituto Murciano de Investigación Biosanitaria IMIB-Arrixaca, Hospital Clínico Universitario Virgen de la Arrixaca, Murcia, Spain
| | - Gabriel Núñez
- Department of Pathology and Rogel Cancer Center, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
| | - Yuan He
- Department of Biochemistry, Microbiology and Immunology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
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18
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Li D, Wang J. Ribosome heterogeneity in stem cells and development. J Cell Biol 2020; 219:e202001108. [PMID: 32330234 PMCID: PMC7265316 DOI: 10.1083/jcb.202001108] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 04/03/2020] [Accepted: 04/06/2020] [Indexed: 02/08/2023] Open
Abstract
Translation control is critical to regulate protein expression. By directly adjusting protein levels, cells can quickly respond to dynamic transitions during stem cell differentiation and embryonic development. Ribosomes are multisubunit cellular assemblies that mediate translation. Previously seen as invariant machines with the same composition of components in all conditions, recent studies indicate that ribosomes are heterogeneous and that different ribosome types can preferentially translate specific subsets of mRNAs. Such heterogeneity and specialized translation functions are very important in stem cells and development, as they allow cells to quickly respond to stimuli through direct changes of protein abundance. In this review, we discuss ribosome heterogeneity that arises from multiple features of rRNAs, including rRNA variants and rRNA modifications, and ribosomal proteins, including their stoichiometry, compositions, paralogues, and posttranslational modifications. We also discuss alterations of ribosome-associated proteins (RAPs), with a particular focus on their consequent specialized translational control in stem cells and development.
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Affiliation(s)
- Dan Li
- Department of Cell, Developmental and Regenerative Biology, The Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, NY
- The Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Jianlong Wang
- Department of Cell, Developmental and Regenerative Biology, The Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, NY
- The Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY
- Department of Medicine, Columbia Center for Human Development, Columbia University Irving Medical Center, New York, NY
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19
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LaFontaine E, Miller CM, Permaul N, Martin ET, Fuchs G. Ribosomal protein RACK1 enhances translation of poliovirus and other viral IRESs. Virology 2020; 545:53-62. [PMID: 32308198 DOI: 10.1016/j.virol.2020.03.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 03/13/2020] [Accepted: 03/13/2020] [Indexed: 02/09/2023]
Abstract
Viruses have evolved strategies to ensure efficient translation using host cell ribosomes and translation factors. In addition to cleaving translation initiation factors required for host cell translation, poliovirus (PV) uses an internal ribosome entry site (IRES). Recent studies suggest that viruses exploit specific ribosomal proteins to enhance translation of their viral proteins. The ribosomal protein receptor for activated C kinase 1 (RACK1), a protein of the 40S ribosomal subunit, was previously shown to mediate translation from the 5' cricket paralysis virus and hepatitis C virus IRESs. Here we found that translation of a PV dual-luciferase reporter shows a moderate dependence on RACK1. However, in the context of a viral infection we observed significantly reduced poliovirus plaque size and titers and delayed host cell translational shut-off. Our findings further illustrate the involvement of the cellular translational machinery during PV infection and how viruses usurp the function of specific ribosomal proteins.
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Affiliation(s)
- Ethan LaFontaine
- Department of Biological Sciences, University at Albany, Albany, NY, 12222, USA
| | - Clare M Miller
- Department of Biological Sciences, University at Albany, Albany, NY, 12222, USA
| | - Natasha Permaul
- Department of Biological Sciences, University at Albany, Albany, NY, 12222, USA
| | - Elliot T Martin
- Department of Biological Sciences, University at Albany, Albany, NY, 12222, USA
| | - Gabriele Fuchs
- Department of Biological Sciences, University at Albany, Albany, NY, 12222, USA; The RNA Institute, University at Albany, NY, 12222, USA.
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20
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Yang H, Yang C, Zhu Q, Wei M, Li Y, Cheng J, Liu F, Wu Y, Zhang J, Zhang C, Wu H. Rack1 Controls Parallel Fiber-Purkinje Cell Synaptogenesis and Synaptic Transmission. Front Cell Neurosci 2019; 13:539. [PMID: 31920545 PMCID: PMC6927999 DOI: 10.3389/fncel.2019.00539] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 11/20/2019] [Indexed: 01/01/2023] Open
Abstract
Purkinje cells (PCs) in the cerebellum receive two excitatory afferents including granule cells-derived parallel fiber (PF) and the climbing fiber. Scaffolding protein Rack1 is highly expressed in the cerebellar PCs. Here, we found delayed formation of specific cerebellar vermis lobule and impaired motor coordination in PC-specific Rack1 conditional knockout mice. Our studies further revealed that Rack1 is essential for PF–PC synapse formation. In addition, Rack1 plays a critical role in regulating synaptic plasticity and long-term depression (LTD) induction of PF–PC synapses without changing the expression of postsynaptic proteins. Together, we have discovered Rack1 as the crucial molecule that controls PF–PC synaptogenesis and synaptic plasticity. Our studies provide a novel molecular insight into the mechanisms underlying the neural development and neuroplasticity in the cerebellum.
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Affiliation(s)
- Haihong Yang
- Department of Neurobiology, Beijing Institute of Basic Medical Sciences, Beijing, China.,Department of Anesthesiology, The General Hospital of Western Theater Command, Chengdu, China
| | - Chaojuan Yang
- Department of Neurobiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Qian Zhu
- Department of Neurobiology, Beijing Institute of Basic Medical Sciences, Beijing, China
| | - Mengping Wei
- Department of Neurobiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Ying Li
- Department of Neurobiology, Beijing Institute of Basic Medical Sciences, Beijing, China
| | - Juanxian Cheng
- Department of Neurobiology, Beijing Institute of Basic Medical Sciences, Beijing, China
| | - Fengjiao Liu
- Department of Neurobiology, Beijing Institute of Basic Medical Sciences, Beijing, China
| | - Yan Wu
- Department of Neurobiology, Beijing Institute of Basic Medical Sciences, Beijing, China
| | - Jiyan Zhang
- Department of Neuroimmunology and Antibody Engineering, Beijing Institute of Basic Medical Sciences, Beijing, China
| | - Chen Zhang
- Department of Neurobiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Haitao Wu
- Department of Neurobiology, Beijing Institute of Basic Medical Sciences, Beijing, China.,Chinese Institute for Brain Research, Beijing, China.,Key Laboratory of Neuroregeneration, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China
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21
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Schmitt K, Valerius O. yRACK1/Asc1 proxiOMICs-Towards Illuminating Ships Passing in the Night. Cells 2019; 8:cells8111384. [PMID: 31689955 PMCID: PMC6912217 DOI: 10.3390/cells8111384] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 10/25/2019] [Accepted: 10/29/2019] [Indexed: 02/01/2023] Open
Abstract
Diverse signals and stress factors regulate the activity and homeostasis of ribosomes in all cells. The Saccharomyces cerevisiae protein Asc1/yRACK1 occupies an exposed site at the head region of the 40S ribosomal subunit (hr40S) and represents a central hub for signaling pathways. Asc1 strongly affects protein phosphorylation and is involved in quality control pathways induced by translation elongation arrest. Therefore, it is important to understand the dynamics of protein formations in the Asc1 microenvironment at the hr40S. We made use of the in vivo protein-proximity labeling technique Biotin IDentification (BioID). Unbiased proxiOMICs from two adjacent perspectives identified nucleocytoplasmic shuttling mRNA-binding proteins, the deubiquitinase complex Ubp3-Bre5, as well as the ubiquitin E3 ligase Hel2 as neighbors of Asc1. We observed Asc1-dependency of hr40S localization of mRNA-binding proteins and the Ubp3 co-factor Bre5. Hel2 and Ubp3-Bre5 are described to balance the mono-ubiquitination of Rps3 (uS3) during ribosome quality control. Here, we show that the absence of Asc1 resulted in massive exposure and accessibility of the C-terminal tail of its ribosomal neighbor Rps3 (uS3). Asc1 and some of its direct neighbors together might form a ribosomal decision tree that is tightly connected to close-by signaling modules.
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Affiliation(s)
- Kerstin Schmitt
- Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Göttingen Center for Molecular Biosciences (GZMB), Georg-August-University Göttingen, 37077 Göttingen, Germany.
| | - Oliver Valerius
- Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Göttingen Center for Molecular Biosciences (GZMB), Georg-August-University Göttingen, 37077 Göttingen, Germany.
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22
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Genuth NR, Barna M. Heterogeneity and specialized functions of translation machinery: from genes to organisms. Nat Rev Genet 2019; 19:431-452. [PMID: 29725087 DOI: 10.1038/s41576-018-0008-z] [Citation(s) in RCA: 147] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Regulation of mRNA translation offers the opportunity to diversify the expression and abundance of proteins made from individual gene products in cells, tissues and organisms. Emerging evidence has highlighted variation in the composition and activity of several large, highly conserved translation complexes as a means to differentially control gene expression. Heterogeneity and specialized functions of individual components of the ribosome and of the translation initiation factor complexes eIF3 and eIF4F, which are required for recruitment of the ribosome to the mRNA 5' untranslated region, have been identified. In this Review, we summarize the evidence for selective mRNA translation by components of these macromolecular complexes as a means to dynamically control the translation of the proteome in time and space. We further discuss the implications of this form of gene expression regulation for a growing number of human genetic disorders associated with mutations in the translation machinery.
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Affiliation(s)
- Naomi R Genuth
- Departments of Genetics and Developmental Biology, Stanford University, Stanford, CA, USA.,Department of Biology, Stanford University, Stanford, CA, USA
| | - Maria Barna
- Departments of Genetics and Developmental Biology, Stanford University, Stanford, CA, USA.
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23
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Johnson AG, Lapointe CP, Wang J, Corsepius NC, Choi J, Fuchs G, Puglisi JD. RACK1 on and off the ribosome. RNA (NEW YORK, N.Y.) 2019; 25:881-895. [PMID: 31023766 PMCID: PMC6573788 DOI: 10.1261/rna.071217.119] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 04/21/2019] [Indexed: 05/17/2023]
Abstract
Receptor for activated C kinase 1 (RACK1) is a eukaryote-specific ribosomal protein (RP) implicated in diverse biological functions. To engineer ribosomes for specific fluorescent labeling, we selected RACK1 as a target given its location on the small ribosomal subunit and other properties. However, prior results suggested that RACK1 has roles both on and off the ribosome, and such an exchange might be related to its various cellular functions and hinder our ability to use RACK1 as a stable fluorescent tag for the ribosome. In addition, the kinetics of spontaneous exchange of RACK1 or any RP from a mature ribosome in vitro remain unclear. To address these issues, we engineered fluorescently labeled human ribosomes via RACK1, and applied bulk and single-molecule biochemical analyses to track RACK1 on and off the human ribosome. Our results demonstrate that, despite its cellular nonessentiality from yeast to humans, RACK1 readily reassociates with the ribosome, displays limited conformational dynamics, and remains stably bound to the ribosome for hours in vitro. This work sheds insight into the biochemical basis of RPs exchange on and off a mature ribosome and provides tools for single-molecule analysis of human translation.
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Affiliation(s)
- Alex G Johnson
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305, USA
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Christopher P Lapointe
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Jinfan Wang
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Nicholas C Corsepius
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Junhong Choi
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305, USA
- Department of Applied Physics, Stanford University, Stanford, California 94305, USA
| | - Gabriele Fuchs
- The RNA Institute, Department of Biological Sciences, University of Albany, Albany, New York 12222, USA
| | - Joseph D Puglisi
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305, USA
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24
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Rollins MG, Jha S, Bartom ET, Walsh D. RACK1 evolved species-specific multifunctionality in translational control through sequence plasticity within a loop domain. J Cell Sci 2019; 132:jcs.228908. [PMID: 31118235 DOI: 10.1242/jcs.228908] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 05/14/2019] [Indexed: 01/23/2023] Open
Abstract
Receptor of activated protein C kinase 1 (RACK1) is a highly conserved eukaryotic protein that regulates several aspects of mRNA translation; yet, how it does so, remains poorly understood. Here we show that, although RACK1 consists largely of conserved β-propeller domains that mediate binding to several other proteins, a short interconnecting loop between two of these blades varies across species to control distinct RACK1 functions during translation. Mutants and chimeras revealed that the amino acid composition of the loop is optimized to regulate interactions with eIF6, a eukaryotic initiation factor that controls 60S biogenesis and 80S ribosome assembly. Separately, phylogenetics revealed that, despite broad sequence divergence of the loop, there is striking conservation of negatively charged residues amongst protists and dicot plants, which is reintroduced to mammalian RACK1 by poxviruses through phosphorylation. Although both charged and uncharged loop mutants affect eIF6 interactions, only a negatively charged plant - but not uncharged yeast or human loop - enhances translation of mRNAs with adenosine-rich 5' untranslated regions (UTRs). Our findings reveal how sequence plasticity within the RACK1 loop confers multifunctionality in translational control across species.
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Affiliation(s)
- Madeline G Rollins
- Department of Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Sujata Jha
- Department of Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Elizabeth T Bartom
- Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Derek Walsh
- Department of Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
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Bowen ME, Attardi LD. The role of p53 in developmental syndromes. J Mol Cell Biol 2019; 11:200-211. [PMID: 30624728 PMCID: PMC6478128 DOI: 10.1093/jmcb/mjy087] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 11/22/2018] [Accepted: 01/06/2019] [Indexed: 12/17/2022] Open
Abstract
While it is well appreciated that loss of the p53 tumor suppressor protein promotes cancer, growing evidence indicates that increased p53 activity underlies the developmental defects in a wide range of genetic syndromes. The inherited or de novo mutations that cause these syndromes affect diverse cellular processes, such as ribosome biogenesis, DNA repair, and centriole duplication, and analysis of human patient samples and mouse models demonstrates that disrupting these cellular processes can activate the p53 pathway. Importantly, many of the developmental defects in mouse models of these syndromes can be rescued by loss of p53, indicating that inappropriate p53 activation directly contributes to their pathogenesis. A role for p53 in driving developmental defects is further supported by the observation that mouse strains with broad p53 hyperactivation, due to mutations affecting p53 pathway components, display a host of tissue-specific developmental defects, including hematopoietic, neuronal, craniofacial, cardiovascular, and pigmentation defects. Furthermore, germline activating mutations in TP53 were recently identified in two human patients exhibiting bone marrow failure and other developmental defects. Studies in mice suggest that p53 drives developmental defects by inducing apoptosis, restraining proliferation, or modulating other developmental programs in a cell type-dependent manner. Here, we review the growing body of evidence from mouse models that implicates p53 as a driver of tissue-specific developmental defects in diverse genetic syndromes.
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Affiliation(s)
- Margot E Bowen
- Division of Radiation and Cancer Biology in the Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA, USA
| | - Laura D Attardi
- Division of Radiation and Cancer Biology in the Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA, USA
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
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Opposite regulation of Wnt/β-catenin and Shh signaling pathways by Rack1 controls mammalian cerebellar development. Proc Natl Acad Sci U S A 2019; 116:4661-4670. [PMID: 30765517 DOI: 10.1073/pnas.1813244116] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The development of the cerebellum depends on intricate processes of neurogenesis, migration, and differentiation of neural stem cells (NSCs) and progenitor cells. Defective cerebellar development often results in motor dysfunctions and psychiatric disorders. Understanding the molecular mechanisms that underlie the complex development of the cerebellum will facilitate the development of novel treatment options. Here, we report that the receptor for activated C kinase (Rack1), a multifaceted signaling adaptor protein, regulates mammalian cerebellar development in a cell type-specific manner. Selective deletion of Rack1 in mouse NSCs or granule neuron progenitors (GNPs), but not Bergmann glial cells (BGs), causes severe defects in cerebellar morphogenesis, including impaired folia and fissure formation. NSCs and GNPs lacking Rack1 exhibit enhanced Wnt/β-catenin signaling but reduced Sonic hedgehog (Shh) signaling. Simultaneous deletion of β-catenin in NSCs, but not GNPs, significantly rescues the Rack1 mutant phenotype. Interestingly, Rack1 controls the activation of Shh signaling by regulating the ubiquitylation and stability of histone deacetylase 1 (HDAC1)/HDAC2. Suppression of HDAC1/HDAC2 activity in the developing cerebellum phenocopies the Rack1 mutant. Together, these results reveal a previously unknown role of Rack1 in controlling mammalian cerebellar development by opposite regulation of Wnt/β-catenin and Shh signaling pathways.
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Cao J, Zhao M, Liu J, Zhang X, Pei Y, Wang J, Yang X, Shen B, Zhang J. RACK1 Promotes Self-Renewal and Chemoresistance of Cancer Stem Cells in Human Hepatocellular Carcinoma through Stabilizing Nanog. Theranostics 2019; 9:811-828. [PMID: 30809310 PMCID: PMC6376462 DOI: 10.7150/thno.29271] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 12/18/2018] [Indexed: 02/06/2023] Open
Abstract
Targeting cancer stem cells (CSCs) has been proposed as a new strategy to eradicate malignancies, including hepatocellular carcinoma (HCC). However, the mechanisms by which CSCs sustain their self-renewal and chemoresistance remain elusive. Nanog is a master transcriptional regulator of stemness, especially in CSCs. Its expression is tightly regulated by the ubiquitin-proteasome system in embryonic stem cells (ESCs). Whether the suppression of Nanog ubiquitination contributes to its over-expression in CSCs has not been explored. In addition, the role of receptor for activated C kinase 1 (RACK1), an adaptor protein implicated in HCC growth, in liver CSC-like traits remains to be determined. Methods: In vitro and in vivo assays were performed to investigate the role of RACK1 in liver CSC-like phenotype and murine ESC function. How RACK1 regulates Nanog expression was explored by immunoblotting and immunohistochemistry. The interaction of RACK1 with Nanog and the consequent effects on Nanog ubiquitination and stemness were then analyzed. Results: RACK1 promotes self-renewal and chemoresistance of human liver CSCs and maintains murine ESC function. Consistently, RACK1 enhances the expression of Nanog in human HCC cells and murine ESCs. The protein levels of RACK1 in clinical HCC tissues positively correlate with those of Nanog. Further exploration indicates that RACK1 directly binds to Nanog, which prevents its recruitment of E3 ubiquitin ligase FBXW8 and ubiquitin-dependent degradation. The interaction with Nanog is essential for RACK1 to promote stemness. Conclusions: Our data provide novel insights into the regulation of Nanog protein levels, as well the key role of RACK1 to enhance self-renewal and chemoresistance of CSCs in human HCC.
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Romano N, Veronese M, Manfrini N, Zolla L, Ceci M. Ribosomal RACK1 promotes proliferation of neuroblastoma cells independently of global translation upregulation. Cell Signal 2019; 53:102-110. [DOI: 10.1016/j.cellsig.2018.09.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2018] [Revised: 09/26/2018] [Accepted: 09/26/2018] [Indexed: 02/04/2023]
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Calamita P, Gatti G, Miluzio A, Scagliola A, Biffo S. Translating the Game: Ribosomes as Active Players. Front Genet 2018; 9:533. [PMID: 30498507 PMCID: PMC6249331 DOI: 10.3389/fgene.2018.00533] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 10/22/2018] [Indexed: 12/18/2022] Open
Abstract
Ribosomes have been long considered as executors of the translational program. The fact that ribosomes can control the translation of specific mRNAs or entire cellular programs is often neglected. Ribosomopathies, inherited diseases with mutations in ribosomal factors, show tissue specific defects and cancer predisposition. Studies of ribosomopathies have paved the way to the concept that ribosomes may control translation of specific mRNAs. Studies in Drosophila and mice support the existence of heterogeneous ribosomes that differentially translate mRNAs to coordinate cellular programs. Recent studies have now shown that ribosomal activity is not only a critical regulator of growth but also of metabolism. For instance, glycolysis and mitochondrial function have been found to be affected by ribosomal availability. Also, ATP levels drop in models of ribosomopathies. We discuss findings highlighting the relevance of ribosome heterogeneity in physiological and pathological conditions, as well as the possibility that in rate-limiting situations, ribosomes may favor some translational programs. We discuss the effects of ribosome heterogeneity on cellular metabolism, tumorigenesis and aging. We speculate a scenario in which ribosomes are not only executors of a metabolic program but act as modulators.
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Affiliation(s)
- Piera Calamita
- INGM, National Institute of Molecular Genetics, "Romeo ed Enrica Invernizzi", Milan, Italy.,Dipartimento di Bioscienze, Università Degli Studi Di Milano, Milan, Italy
| | - Guido Gatti
- INGM, National Institute of Molecular Genetics, "Romeo ed Enrica Invernizzi", Milan, Italy.,Dipartimento di Bioscienze, Università Degli Studi Di Milano, Milan, Italy
| | - Annarita Miluzio
- INGM, National Institute of Molecular Genetics, "Romeo ed Enrica Invernizzi", Milan, Italy
| | - Alessandra Scagliola
- INGM, National Institute of Molecular Genetics, "Romeo ed Enrica Invernizzi", Milan, Italy.,Dipartimento di Bioscienze, Università Degli Studi Di Milano, Milan, Italy
| | - Stefano Biffo
- INGM, National Institute of Molecular Genetics, "Romeo ed Enrica Invernizzi", Milan, Italy.,Dipartimento di Bioscienze, Università Degli Studi Di Milano, Milan, Italy
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30
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RACK1 Specifically Regulates Translation through Its Binding to Ribosomes. Mol Cell Biol 2018; 38:MCB.00230-18. [PMID: 30201806 PMCID: PMC6234289 DOI: 10.1128/mcb.00230-18] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Accepted: 08/26/2018] [Indexed: 12/22/2022] Open
Abstract
The translational capability of ribosomes deprived of specific nonfundamental ribosomal proteins may be altered. Physiological mechanisms are scanty, and it is unclear whether free ribosomal proteins can cross talk with the signaling machinery. The translational capability of ribosomes deprived of specific nonfundamental ribosomal proteins may be altered. Physiological mechanisms are scanty, and it is unclear whether free ribosomal proteins can cross talk with the signaling machinery. RACK1 (receptor for activated C kinase 1) is a highly conserved scaffold protein, located on the 40S subunit near the mRNA exit channel. RACK1 is involved in a variety of intracellular contexts, both on and off the ribosomes, acting as a receptor for proteins in signaling, such as the protein kinase C (PKC) family. Here we show that the binding of RACK1 to ribosomes is essential for full translation of capped mRNAs and efficient recruitment of eukaryotic initiation factor 4E (eIF4E). In vitro, when RACK1 is partially depleted, supplementing the ribosome machinery with wild-type RACK1 restores the translational capability, whereas the addition of a RACK1 mutant that is unable to bind ribosomes does not. Outside the ribosome, RACK1 has a reduced half-life. By accumulating in living cells, free RACK1 exerts an inhibitory phenotype, impairing cell cycle progression and repressing global translation. Here we present RACK1 binding to ribosomes as a crucial way to regulate translation, possibly through interaction with known partners on or off the ribosome that are involved in signaling.
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31
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Leggio L, Guarino F, Magrì A, Accardi-Gheit R, Reina S, Specchia V, Damiano F, Tomasello MF, Tommasino M, Messina A. Mechanism of translation control of the alternative Drosophila melanogaster Voltage Dependent Anion-selective Channel 1 mRNAs. Sci Rep 2018; 8:5347. [PMID: 29593233 PMCID: PMC5871876 DOI: 10.1038/s41598-018-23730-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 03/19/2018] [Indexed: 01/08/2023] Open
Abstract
The eukaryotic porin, also called the Voltage Dependent Anion-selective Channel (VDAC), is the main pore-forming protein of the outer mitochondrial membrane. In Drosophila melanogaster, a cluster of genes evolutionarily linked to VDAC is present on chromosome 2L. The main VDAC isoform, called VDAC1 (Porin1), is expressed from the first gene of the cluster. The porin1 gene produces two splice variants, 1A-VDAC and 1B-VDAC, with the same coding sequence but different 5' untranslated regions (UTRs). Here, we studied the influence of the two 5' UTRs, 1A-5' UTR and 1B-5' UTR, on transcription and translation of VDAC1 mRNAs. In porin-less yeast cells, transformation with a construct carrying 1A-VDAC results in the expression of the corresponding protein and in complementation of a defective cell phenotype, whereas the 1B-VDAC sequence actively represses VDAC expression. Identical results were obtained using constructs containing the two 5' UTRs upstream of the GFP reporter. A short region of 15 nucleotides in the 1B-5' UTR should be able to pair with an exposed helix of 18S ribosomal RNA (rRNA), and this interaction could be involved in the translational repression. Our data suggest that contacts between the 5' UTR and 18S rRNA sequences could modulate the translation of Drosophila 1B-VDAC mRNA. The evolutionary significance of this finding is discussed.
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Affiliation(s)
- L Leggio
- Department of Biological, University of Catania, Geological and Environmental Sciences, Catania, 95125, Italy.,Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, 95123, Italy
| | - F Guarino
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, 95123, Italy.,National Institute of Biostructures and Biosystems (INBB), Catania, Italy
| | - A Magrì
- Department of Biological, University of Catania, Geological and Environmental Sciences, Catania, 95125, Italy
| | - R Accardi-Gheit
- International Agency for Research on Cancer (IARC), World Health Organization, Lyon, 69372, France
| | - S Reina
- Department of Biological, University of Catania, Geological and Environmental Sciences, Catania, 95125, Italy.,Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, 95123, Italy
| | - V Specchia
- Department of Biological and Environmental Sciences and Technologies (DiSTeBA), University of Salento, Lecce, Italy
| | - F Damiano
- Department of Biological and Environmental Sciences and Technologies (DiSTeBA), University of Salento, Lecce, Italy
| | - M F Tomasello
- IBB-CNR, Institute of Biostructure and Bioimaging, Section of Catania, Via Paolo Gaifami, 18-95126, Catania, Italy
| | - M Tommasino
- International Agency for Research on Cancer (IARC), World Health Organization, Lyon, 69372, France
| | - A Messina
- Department of Biological, University of Catania, Geological and Environmental Sciences, Catania, 95125, Italy. .,National Institute of Biostructures and Biosystems (INBB), Catania, Italy.
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32
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Liu B, Wang C, Chen P, Cheng B, Cheng Y. RACKI induces chemotherapy resistance in esophageal carcinoma by upregulating the PI3K/AKT pathway and Bcl-2 expression. Onco Targets Ther 2018; 11:211-220. [PMID: 29379302 PMCID: PMC5757499 DOI: 10.2147/ott.s152818] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Introduction Accumulating evidence indicates that RACK1 is involved in the progression of tumors. We aimed to evaluate the function of RACK1 in esophageal squamous cell carcinoma (ESCC) and its role in the mechanism of chemotherapy resistance. Materials and methods Transfected ESCC cell lines with plasmids expressed shRACK1 or open reading frame (ORF) targeting RACK1 and established stable cell lines. We then examined the effects of RACK1 on cell proliferation and chemotherapy resistance in ESCC cell lines, and the expression of AKT, pAKT, ERK1/2, Bcl-2, and Bim was introduced to further detect the association between RACK1 and chemotherapy resistance. Results The proliferation ability of ESCC cells was improved in the overexpression RACK1 groups (P<0.001) and decreased in the transfected shRACK1 groups (P<0.001) compared with the control ones. Meanwhile, upregulation of RACK1 significantly suppressed cisplatin-induced apoptosis in Eca109 and EC9706 cells, while downregulation of RACK1 promoted the sensitivity compared to the control group (Eca109: P<0.001 for shRACK1, P<0.01 for shNC, and P<0.001 for overexpression group; EC9706: P<0.001 for shRACK1, P<0.001 for shNC, and P<0.05 for overexpression group). Furthermore, we found that RACK1 could activate the PI3K/AKT pathway and increase the expression level of Bcl-2 in ESCC, which leads to the enhancement of chemoresistance in ESCC. Conclusion RACK1 promotes proliferation and chemotherapy resistance in ESCC by activating the PI3K/AKT pathway and upregulating the Bcl-2 expression.
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Affiliation(s)
- Bowen Liu
- Department of Radiation Oncology, Qilu Hospital of Shandong University, Jinan, Shandong, People's Republic of China
| | - Cong Wang
- Department of Radiation Oncology, Qilu Hospital of Shandong University, Jinan, Shandong, People's Republic of China
| | - Pengxiang Chen
- Department of Radiation Oncology, Qilu Hospital of Shandong University, Jinan, Shandong, People's Republic of China
| | - Bo Cheng
- Department of Radiation Oncology, Shandong Provincial Cancer Hospital, Jinan, Shandong, People's Republic of China
| | - Yufeng Cheng
- Department of Radiation Oncology, Qilu Hospital of Shandong University, Jinan, Shandong, People's Republic of China
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Cheng ZF, Pai RK, Cartwright CA. Rack1 function in intestinal epithelia: regulating crypt cell proliferation and regeneration and promoting differentiation and apoptosis. Am J Physiol Gastrointest Liver Physiol 2018; 314:G1-G13. [PMID: 28935684 PMCID: PMC5866376 DOI: 10.1152/ajpgi.00240.2017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 09/07/2017] [Accepted: 09/11/2017] [Indexed: 01/31/2023]
Abstract
Previously, we showed that receptor for activated C kinase 1 (Rack1) regulates growth of colon cells in vitro, partly by suppressing Src kinase activity at key cell cycle checkpoints, in apoptotic and cell survival pathways and at cell-cell adhesions. Here, we generated mouse models of Rack1 deficiency to assess Rack1's function in intestinal epithelia in vivo. Intestinal Rack1 deficiency resulted in proliferation of crypt cells, diminished differentiation of crypt cells into enterocyte, goblet, and enteroendocrine cell lineages, and expansion of Paneth cell populations. Following radiation injury, the morphology of Rack1-deleted small bowel was strikingly abnormal with development of large polypoid structures that contained many partly formed villi, numerous back-to-back elongated and regenerating crypts, and high-grade dysplasia in surface epithelia. These abnormalities were not observed in Rack1-expressing areas of intestine or in control mice. Following irradiation, apoptosis of enterocytes was strikingly reduced in Rack1-deleted epithelia. These novel findings reveal key functions for Rack1 in regulating growth of intestinal epithelia: suppressing crypt cell proliferation and regeneration, promoting differentiation and apoptosis, and repressing development of neoplasia. NEW & NOTEWORTHY Our findings reveal novel functions for receptor for activated C kinase 1 (Rack1) in regulating growth of intestinal epithelia: suppressing crypt cell proliferation and regeneration, promoting differentiation and apoptosis, and repressing development of neoplasia.
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Affiliation(s)
- Zhuan-Fen Cheng
- Department of Medicine, Stanford University , Stanford, California
| | - Reetesh K Pai
- Department of Pathology, University of Pittsburgh , Pittsburgh, Pennsylvania
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34
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Manfrini N, Ricciardi S, Miluzio A, Fedeli M, Scagliola A, Gallo S, Brina D, Adler T, Busch DH, Gailus-Durner V, Fuchs H, Hrabě de Angelis M, Biffo S. High levels of eukaryotic Initiation Factor 6 (eIF6) are required for immune system homeostasis and for steering the glycolytic flux of TCR-stimulated CD4 + T cells in both mice and humans. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2017; 77:69-76. [PMID: 28743432 DOI: 10.1016/j.dci.2017.07.022] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2017] [Revised: 07/21/2017] [Accepted: 07/21/2017] [Indexed: 06/07/2023]
Abstract
Eukaryotic Initiation Factor 6 (eIF6) is required for 60S ribosomal subunit biogenesis and efficient initiation of translation. Intriguingly, in both mice and humans, endogenous levels of eIF6 are detrimental as they act as tumor and obesity facilitators, raising the question on the evolutionary pressure that maintains high eIF6 levels. Here we show that, in mice and humans, high levels of eIF6 are required for proper immune functions. First, eIF6 heterozygous (het) mice show an increased mortality during viral infection and a reduction of peripheral blood CD4+ Effector Memory T cells. In human CD4+ T cells, eIF6 levels rapidly increase upon T-cell receptor activation and drive the glycolytic switch and the acquisition of effector functions. Importantly, in CD4+ T cells, eIF6 levels control interferon-γ (IFN-γ) secretion without affecting proliferation. In conclusion, the immune system has a high evolutionary pressure for the maintenance of a dynamic and powerful regulation of the translational machinery.
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Affiliation(s)
- Nicola Manfrini
- National Institute of Molecular Genetics "Romeo ed Enrica Invernizzi" - INGM, Via F. Sforza 35, 20122 Milan, Italy.
| | - Sara Ricciardi
- National Institute of Molecular Genetics "Romeo ed Enrica Invernizzi" - INGM, Via F. Sforza 35, 20122 Milan, Italy
| | - Annarita Miluzio
- National Institute of Molecular Genetics "Romeo ed Enrica Invernizzi" - INGM, Via F. Sforza 35, 20122 Milan, Italy
| | - Maya Fedeli
- Experimental Immunology Unit, Division of Immunology, Transplantation and Infectious Diseases, DIBIT, H. San Raffaele Scientific Institute, Via Olgettina 58, 20132 Milan, Italy
| | - Alessandra Scagliola
- National Institute of Molecular Genetics "Romeo ed Enrica Invernizzi" - INGM, Via F. Sforza 35, 20122 Milan, Italy; Department of Biosciences, University of Milan, Via Celoria 26, 20133 Milan, Italy
| | - Simone Gallo
- National Institute of Molecular Genetics "Romeo ed Enrica Invernizzi" - INGM, Via F. Sforza 35, 20122 Milan, Italy; Department of Biosciences, University of Milan, Via Celoria 26, 20133 Milan, Italy
| | - Daniela Brina
- Molecular Oncology Group, Institute of Oncology Research (IOR), Oncology Institute of Southern Switzerland (IOSI), Via Mirasole 22A, Bellinzona, Switzerland
| | - Thure Adler
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, 85764 Neuherberg, Germany
| | - Dirk H Busch
- Institute for Medical Microbiology, Immunology and Hygiene, Technische Universität München, Trogerstrasse 30, 81675 Munich, Germany
| | - Valerie Gailus-Durner
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, 85764 Neuherberg, Germany
| | - Helmut Fuchs
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, 85764 Neuherberg, Germany
| | - Martin Hrabě de Angelis
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, 85764 Neuherberg, Germany; Center of Life and Food Sciences Weihenstephan, Technische Universität München, 85354 Freising, Germany; German Center for Diabetes Research, 85764 Neuherberg, Germany
| | - Stefano Biffo
- National Institute of Molecular Genetics "Romeo ed Enrica Invernizzi" - INGM, Via F. Sforza 35, 20122 Milan, Italy; Department of Biosciences, University of Milan, Via Celoria 26, 20133 Milan, Italy.
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35
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RACK1 depletion in the ribosome induces selective translation for non-canonical autophagy. Cell Death Dis 2017; 8:e2800. [PMID: 28518135 PMCID: PMC5520723 DOI: 10.1038/cddis.2017.204] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 03/30/2017] [Accepted: 04/03/2017] [Indexed: 12/25/2022]
Abstract
RACK1, which was first demonstrated as a substrate of PKCβ II, functions as a scaffold protein and associates with the 40S small ribosomal subunit. According to previous reports, ribosomal RACK1 was also suggested to control translation depending on the status in translating ribosome. We here show that RACK1 knockdown induces autophagy independent of upstream canonical factors such as Beclin1, Atg7 and Atg5/12 conjugates. We further report that RACK1 knockdown induces the association of mRNAs of LC3 and Bcl-xL with polysomes, indicating increased translation of these proteins. Therefore, we propose that the RACK1 depletion-induced autophagy is distinct from canonical autophagy. Finally, we confirm that cells expressing mutant RACK1 (RACK1R36D/K38E) defective in ribosome binding showed the same result as RACK1-knockdown cells. Altogether, our data clearly show that the depletion of ribosomal RACK1 alters the capacity of the ribosome to translate specific mRNAs, resulting in selective translation of mRNAs of genes for non-canonical autophagy induction.
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36
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Campagne C, Reyes-Gomez E, Picco ME, Loiodice S, Salaun P, Ezagal J, Bernex F, Commère PH, Pons S, Esquerre D, Bourneuf E, Estellé J, Maskos U, Lopez-Bergami P, Aubin-Houzelstein G, Panthier JJ, Egidy G. RACK1 cooperates with NRAS Q61K to promote melanoma in vivo. Cell Signal 2017; 36:255-266. [PMID: 28343944 DOI: 10.1016/j.cellsig.2017.03.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Revised: 03/20/2017] [Accepted: 03/22/2017] [Indexed: 12/24/2022]
Abstract
Melanoma is the deadliest skin cancer. RACK1 (Receptor for activated protein kinase C) protein was proposed as a biological marker of melanoma in human and domestic animal species harboring spontaneous melanomas. As a scaffold protein, RACK1 is able to coordinate the interaction of key signaling molecules implicated in both physiological cellular functions and tumorigenesis. A role for RACK1 in rewiring ERK and JNK signaling pathways in melanoma cell lines had been proposed. Here, we used a genetic approach to test this hypothesis in vivo in the mouse. We show that Rack1 knock-down in the mouse melanoma cell line B16 reduces invasiveness and induces cell differentiation. We have developed the first mouse model for RACK1 gain of function, Tyr::Rack1-HA transgenic mice, targeting RACK1 to melanocytes in vivo. RACK1 overexpression was not sufficient to initiate melanomas despite activated ERK and AKT. However, in a context of melanoma predisposition, RACK1 overexpression reduced latency and increased incidence and metastatic rate. In primary melanoma cells from Tyr::Rack1-HA, Tyr::NRasQ61K mice, activated JNK (c-Jun N-terminal kinase) and activated STAT3 (signal transducer and activator of transcription 3) acted as RACK1 oncogenic partners in tumoral progression. A sequential and coordinated activation of ERK, JNK and STAT3 with RACK1 is shown to accelerate aggressive melanoma development in vivo.
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Affiliation(s)
- C Campagne
- INRA, UMR955 Génétique Fonctionnelle et Médicale, Ecole Nationale Vétérinaire d'Alfort, F-94704 Maisons-Alfort, France; Université Paris-Est, Ecole Nationale Vétérinaire d'Alfort, UMR955 Génétique Fonctionnelle et Médicale, F-94704 Maisons-Alfort, France.
| | - E Reyes-Gomez
- INRA, UMR955 Génétique Fonctionnelle et Médicale, Ecole Nationale Vétérinaire d'Alfort, F-94704 Maisons-Alfort, France; Université Paris-Est, Ecole Nationale Vétérinaire d'Alfort, UMR955 Génétique Fonctionnelle et Médicale, F-94704 Maisons-Alfort, France; Université Paris-Est, Ecole Nationale Vétérinaire d'Alfort, Unité d'Embryologie, d'Histologie et d'Anatomie Pathologique, F-94704 Maisons-Alfort, France
| | - M E Picco
- Instituto de Medicina y Biologia Experimental, CONICET, Buenos Aires, Argentina
| | - S Loiodice
- INRA, UMR955 Génétique Fonctionnelle et Médicale, Ecole Nationale Vétérinaire d'Alfort, F-94704 Maisons-Alfort, France; Université Paris-Est, Ecole Nationale Vétérinaire d'Alfort, UMR955 Génétique Fonctionnelle et Médicale, F-94704 Maisons-Alfort, France
| | - P Salaun
- INRA, UMR955 Génétique Fonctionnelle et Médicale, Ecole Nationale Vétérinaire d'Alfort, F-94704 Maisons-Alfort, France; Université Paris-Est, Ecole Nationale Vétérinaire d'Alfort, UMR955 Génétique Fonctionnelle et Médicale, F-94704 Maisons-Alfort, France
| | - J Ezagal
- INRA, UMR955 Génétique Fonctionnelle et Médicale, Ecole Nationale Vétérinaire d'Alfort, F-94704 Maisons-Alfort, France; Université Paris-Est, Ecole Nationale Vétérinaire d'Alfort, UMR955 Génétique Fonctionnelle et Médicale, F-94704 Maisons-Alfort, France
| | - F Bernex
- INRA, UMR955 Génétique Fonctionnelle et Médicale, Ecole Nationale Vétérinaire d'Alfort, F-94704 Maisons-Alfort, France; Université Paris-Est, Ecole Nationale Vétérinaire d'Alfort, UMR955 Génétique Fonctionnelle et Médicale, F-94704 Maisons-Alfort, France; Université Paris-Est, Ecole Nationale Vétérinaire d'Alfort, Unité d'Embryologie, d'Histologie et d'Anatomie Pathologique, F-94704 Maisons-Alfort, France
| | - P H Commère
- Plateforme de Cytométrie, Département d'Immunologie, Institut Pasteur, F-75724 Paris, France
| | - S Pons
- Unité Neurobiologie Intégrative des Systèmes Cholinergiques, UMR 3571, CNRS, Institut Pasteur, F75724 Paris Cedex 15, France
| | - D Esquerre
- GenPhySE, Université de Toulouse, INRA, INPT, ENVT, Castanet Tolosan, France
| | - E Bourneuf
- GABI, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France; LREG, CEA, Université Paris-Saclay, F-78352 Jouy-en-Josas, France
| | - J Estellé
- GABI, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - U Maskos
- Unité Neurobiologie Intégrative des Systèmes Cholinergiques, UMR 3571, CNRS, Institut Pasteur, F75724 Paris Cedex 15, France
| | - P Lopez-Bergami
- Instituto de Medicina y Biologia Experimental, CONICET, Buenos Aires, Argentina; Centro de Estudios Biomédicos, Biotecnologicos, Ambientales y Diagnostico, Universidad Malmonides, CONICET, Buenos Aires, Argentina
| | - G Aubin-Houzelstein
- INRA, UMR955 Génétique Fonctionnelle et Médicale, Ecole Nationale Vétérinaire d'Alfort, F-94704 Maisons-Alfort, France; Université Paris-Est, Ecole Nationale Vétérinaire d'Alfort, UMR955 Génétique Fonctionnelle et Médicale, F-94704 Maisons-Alfort, France
| | - J J Panthier
- INRA, UMR955 Génétique Fonctionnelle et Médicale, Ecole Nationale Vétérinaire d'Alfort, F-94704 Maisons-Alfort, France; Université Paris-Est, Ecole Nationale Vétérinaire d'Alfort, UMR955 Génétique Fonctionnelle et Médicale, F-94704 Maisons-Alfort, France; CNRS URM 3738, USC INRA 2026, F-75724, France; Institut Pasteur, Département de Biologie du Développement et Cellules Souches, Génétique fonctionnelle de la Souris, 25 rue du Docteur Roux, Paris F-75724, France
| | - G Egidy
- INRA, UMR955 Génétique Fonctionnelle et Médicale, Ecole Nationale Vétérinaire d'Alfort, F-94704 Maisons-Alfort, France; Université Paris-Est, Ecole Nationale Vétérinaire d'Alfort, UMR955 Génétique Fonctionnelle et Médicale, F-94704 Maisons-Alfort, France; GABI, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France.
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Kershner L, Welshhans K. RACK1 is necessary for the formation of point contacts and regulates axon growth. Dev Neurobiol 2017; 77:1038-1056. [PMID: 28245531 DOI: 10.1002/dneu.22491] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 02/17/2017] [Accepted: 02/19/2017] [Indexed: 11/08/2022]
Abstract
Receptor for activated C kinase 1 (RACK1) is a multifunctional ribosomal scaffolding protein that can interact with multiple signaling molecules concurrently through its seven WD40 repeats. We recently found that RACK1 is localized to mammalian growth cones, prompting an investigation into its role during neural development. Here, we show for the first time that RACK1 localizes to point contacts within mouse cortical growth cones. Point contacts are adhesion sites that link the actin network within growth cones to the extracellular matrix, and are necessary for appropriate axon guidance. Our experiments show that RACK1 is necessary for point contact formation. Brain-derived neurotrophic factor (BDNF) stimulates an increase in point contact density, which was eliminated by RACK1 shRNA or overexpression of a nonphosphorylatable mutant form of RACK1. We also found that axonal growth requires both RACK1 expression and phosphorylation. We have previously shown that the local translation of β-actin mRNA within growth cones is necessary for appropriate axon guidance and is dependent on RACK1. Thus, we examined the location of members of the local translation complex relative to point contacts. Indeed, both β-actin mRNA and RACK1 colocalize with point contacts, and this colocalization increases following BDNF stimulation. This implies the novel finding that local translation is regulated at point contacts. Taken together, these data suggest that point contacts are a targeted site of local translation within growth cones, and RACK1 is a critical member of the point contact complex and necessary for appropriate neural development. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 77: 1038-1056, 2017.
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Affiliation(s)
- Leah Kershner
- Department of Biological Sciences, Kent State University, Kent, Ohio, 44242
| | - Kristy Welshhans
- Department of Biological Sciences, Kent State University, Kent, Ohio, 44242.,School of Biomedical Sciences, Kent State University, Kent, Ohio, 44242
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Nielsen MH, Flygaard RK, Jenner LB. Structural analysis of ribosomal RACK1 and its role in translational control. Cell Signal 2017; 35:272-281. [PMID: 28161490 DOI: 10.1016/j.cellsig.2017.01.026] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Accepted: 01/31/2017] [Indexed: 12/28/2022]
Abstract
Receptor for Activated C-Kinase 1 (RACK1) belongs to the WD40 family of proteins, known to act as scaffolding proteins in interaction networks. Accordingly, RACK1 is found to have numerous interacting partners ranging from kinases and signaling proteins to membrane bound receptors and ion channels. Interestingly, RACK1 has also been identified as a ribosomal protein present in all eukaryotic ribosomes. Structures of eukaryotic ribosomes have shown RACK1 to be located at the back of the head of the small ribosomal subunit. This suggests that RACK1 could act as a ribosomal scaffolding protein recruiting regulators of translation to the ribosome, and several studies have in fact found RACK1 to play a role in regulation of translation. To fully understand the role of RACK1 we need to understand whether the many reported interaction partners of RACK1 bind to free or ribosomal RACK1. In this review we provide a structural analysis of ribosome-bound RACK1 to provide a basis for answering this fundamental question. Our analysis shows that RACK1 is tightly bound to the ribosome through highly conserved and specific interactions confirming RACK1 as an integral ribosomal protein. Furthermore, we have analyzed whether reported binding sites for RACK1 interacting partners with a proposed role in translational control are accessible on ribosomal RACK1. Our analysis shows that most of the interaction partners with putative regulatory functions have binding sites that are available on ribosomal RACK1, supporting the role of RACK1 as a ribosomal signaling hub. We also discuss the possible role for RACK1 in recruitment of ribosomes to focal adhesion sites and regulation of local translation during cell spreading and migration.
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Affiliation(s)
- Maja Holch Nielsen
- Department of Molecular Biology and Genetics, Gustav Wieds Vej 10C, DK-8000 Aarhus C, Aarhus University, Denmark
| | - Rasmus Kock Flygaard
- Department of Molecular Biology and Genetics, Gustav Wieds Vej 10C, DK-8000 Aarhus C, Aarhus University, Denmark
| | - Lasse Bohl Jenner
- Department of Molecular Biology and Genetics, Gustav Wieds Vej 10C, DK-8000 Aarhus C, Aarhus University, Denmark
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Yuan L, Su Y, Zhou S, Feng Y, Guo W, Wang X. A RACK1-like protein regulates hyphal morphogenesis, root entry and in vivo virulence in Verticillium dahliae. Fungal Genet Biol 2017; 99:52-61. [PMID: 28089629 DOI: 10.1016/j.fgb.2017.01.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 11/28/2016] [Accepted: 01/08/2017] [Indexed: 02/07/2023]
Abstract
To identify key genes expressed in Verticillium dahliae in early stages of infection of cotton roots, spore suspensions of eight V. dahliae isolates with different virulence levels were induced by cotton roots and genes expressed in these isolates during the early stages of infection were profiled. A gene that was differentially expressed between highly and less virulent strains was identified. Cloning and bioinformatics analysis of the gene suggested that it belongs to the putative Gβ-like/RACK1 protein family, and has seven WD40 domains. Targeted deletion of the gene revealed that it controls a number of growth-related phenotypes, including conidia and microsclerotia production, normal spore germination and hyphal development. RACK1 is a component of eukaryotic ribosomes, and here we found by qRT-PCR that disruption of RACK1 in V. dahliae (designated VdRACK1) significantly altered the transcriptional levels of other ribosomal proteins, suggesting possible global effects of VdRACK1 deletion on the protein translation of other genes. VdRACK1-null mutants lost the ability to penetrate intact cotton roots. However, the mutant strain was able to infect root-wounded cotton plants and, intriguingly, resulted in a hypervirulent phenotype, implicating a role for VdRACK1 in the restriction of rampant growth within the plant.
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Affiliation(s)
- Lei Yuan
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Yaxin Su
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Shuai Zhou
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Yigao Feng
- State Key Laboratory of Crop Genetics & Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China
| | - Wangzhen Guo
- State Key Laboratory of Crop Genetics & Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China
| | - Xinyu Wang
- College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China.
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40
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Abstract
Receptor for activated C kinase 1 (RACK1) is an evolutionarily conserved scaffolding protein within the tryptophan-aspartate (WD) repeat family of proteins. RACK1 can bind multiple signaling molecules concurrently, as well as stabilize and anchor proteins. RACK1 also plays an important role at focal adhesions, where it acts to regulate cell migration. In addition, RACK1 is a ribosomal binding protein and thus, regulates translation. Despite these numerous functions, little is known about how RACK1 regulates nervous system development. Here, we review three studies that examine the role of RACK1 in neural development. In brief, these papers demonstrate that (1) RACK-1, the C. elegans homolog of mammalian RACK1, is required for axon guidance; (2) RACK1 is required for neurite extension of neuronally differentiated rat PC12 cells; and (3) RACK1 is required for axon outgrowth of primary mouse cortical neurons. Thus, it is evident that RACK1 is critical for appropriate neural development in a wide range of species, and future discoveries could reveal whether RACK1 and its signaling partners are potential targets for treatment of neurodevelopmental disorders or a therapeutic approach for axonal regeneration.
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Affiliation(s)
- Leah Kershner
- Department of Biological Sciences, Kent State University, Kent, OH, USA
| | - Kristy Welshhans
- Department of Biological Sciences, Kent State University, Kent, OH, USA.,School of Biomedical Sciences, Kent State University, Kent, OH, USA
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Kong Q, Gao L, Niu Y, Gongpan P, Xu Y, Li Y, Xiong W. RACK1 is required for adipogenesis. Am J Physiol Cell Physiol 2016; 311:C831-C836. [PMID: 27653985 DOI: 10.1152/ajpcell.00224.2016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 09/19/2016] [Indexed: 11/22/2022]
Abstract
Adipose tissue plays a critical role in metabolic diseases and the maintenance of energy homeostasis. RACK1 has been identified as an adaptor protein involved in multiple intracellular signal transduction pathways and diseases. However, whether it regulates adipogenesis remains unknown. Here, we reported that RACK1 is expressed in 3T3-L1 cells and murine white adipose tissue and that RACK1 knockdown by shRNA profoundly suppressed adipogenesis by reducing the expression of PPAR-γ and C/EBP-β. Depletion of RACK1 increased β-catenin protein levels and activated Wnt signaling. Furthermore, RACK1 knockdown also suppressed the PI3K-Akt-mTOR-S6K signaling pathway by reducing the PI3K p85α, pAkt T473, and S6K p70. Taken together, these results demonstrate that RACK1 is a novel factor required for adipocyte differentiation by emerging Wnt/β-catenin signaling and PI3K-Akt-mTOR-S6K signaling pathway(s).
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Affiliation(s)
- Qinghua Kong
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
| | - Lan Gao
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
- Graduate University of the Chinese Academy of Sciences, Beijing, China
| | - Yanfen Niu
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
- Biomedical Engineering Research Center, Kunming Medical University, Kunming, China; and
| | - Pianchou Gongpan
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
- Graduate University of the Chinese Academy of Sciences, Beijing, China
| | - Yuhui Xu
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
- Graduate University of the Chinese Academy of Sciences, Beijing, China
| | - Yan Li
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
- Yunnan Key Laboratory of Natural Medicinal Chemistry, Kumming, China
| | - Wenyong Xiong
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
- Yunnan Key Laboratory of Natural Medicinal Chemistry, Kumming, China
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Ballek O, Valečka J, Dobešová M, Broučková A, Manning J, Řehulka P, Stulík J, Filipp D. TCR Triggering Induces the Formation of Lck-RACK1-Actinin-1 Multiprotein Network Affecting Lck Redistribution. Front Immunol 2016; 7:449. [PMID: 27833610 PMCID: PMC5081367 DOI: 10.3389/fimmu.2016.00449] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 10/10/2016] [Indexed: 02/02/2023] Open
Abstract
The initiation of T-cell signaling is critically dependent on the function of the member of Src family tyrosine kinases, Lck. Upon T-cell antigen receptor (TCR) triggering, Lck kinase activity induces the nucleation of signal-transducing hubs that regulate the formation of complex signaling network and cytoskeletal rearrangement. In addition, the delivery of Lck function requires rapid and targeted membrane redistribution, but the mechanism underpinning this process is largely unknown. To gain insight into this process, we considered previously described proteins that could assist in this process via their capacity to interact with kinases and regulate their intracellular translocations. An adaptor protein, receptor for activated C kinase 1 (RACK1), was chosen as a viable option, and its capacity to bind Lck and aid the process of activation-induced redistribution of Lck was assessed. Our microscopic observation showed that T-cell activation induces a rapid, concomitant, and transient co-redistribution of Lck and RACK1 into the forming immunological synapse. Consistent with this observation, the formation of transient RACK1-Lck complexes were detectable in primary CD4+ T-cells with their maximum levels peaking 10 s after TCR-CD4 co-aggregation. Moreover, RACK1 preferentially binds to a pool of kinase active pY394Lck, which co-purifies with high molecular weight cellular fractions. The formation of RACK1-Lck complexes depends on functional SH2 and SH3 domains of Lck and includes several other signaling and cytoskeletal elements that transiently bind the complex. Notably, the F-actin-crosslinking protein, α-actinin-1, binds to RACK1 only in the presence of kinase active Lck suggesting that the formation of RACK1-pY394Lck-α-actinin-1 complex serves as a signal module coupling actin cytoskeleton bundling with productive TCR/CD4 triggering. In addition, the treatment of CD4+ T-cells with nocodazole, which disrupts the microtubular network, also blocked the formation of RACK1-Lck complexes. Importantly, activation-induced Lck redistribution was diminished in primary CD4+ T-cells by an adenoviral-mediated knockdown of RACK1. These results demonstrate that in T cells, RACK1, as an essential component of the multiprotein complex which upon TCR engagement, links the binding of kinase active Lck to elements of the cytoskeletal network and affects the subcellular redistribution of Lck.
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Affiliation(s)
- Ondřej Ballek
- Laboratory of Immunobiology, Institute of Molecular Genetics AS CR , Prague , Czech Republic
| | - Jan Valečka
- Laboratory of Immunobiology, Institute of Molecular Genetics AS CR , Prague , Czech Republic
| | - Martina Dobešová
- Laboratory of Immunobiology, Institute of Molecular Genetics AS CR , Prague , Czech Republic
| | - Adéla Broučková
- Laboratory of Immunobiology, Institute of Molecular Genetics AS CR , Prague , Czech Republic
| | - Jasper Manning
- Laboratory of Immunobiology, Institute of Molecular Genetics AS CR , Prague , Czech Republic
| | - Pavel Řehulka
- Faculty of Military Health Sciences, Institute of Molecular Pathology , Hradec Králové , Czech Republic
| | - Jiří Stulík
- Faculty of Military Health Sciences, Institute of Molecular Pathology , Hradec Králové , Czech Republic
| | - Dominik Filipp
- Laboratory of Immunobiology, Institute of Molecular Genetics AS CR , Prague , Czech Republic
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Oliveira C, Carvalho PC, Alves LR, Goldenberg S. The Role of the Trypanosoma cruzi TcNRBD1 Protein in Translation. PLoS One 2016; 11:e0164650. [PMID: 27760165 PMCID: PMC5070865 DOI: 10.1371/journal.pone.0164650] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 09/28/2016] [Indexed: 11/28/2022] Open
Abstract
The regulation of gene expression in trypanosomatids occurs mainly at the post-transcriptional level. Despite the importance of this type of control in Trypanosoma cruzi, few RNA binding proteins have been characterized. The RRM domain (RNA Recognition Motif) is one of the most abundant domains found in RNA-binding proteins in higher eukaryotes. Proteins containing the RRM domain are involved in the majority of post-transcriptional processes regulating gene expression. In this work, we aimed to characterize the protein TcNRBD1 from T. cruzi. TcNRBD1 is an RNA-binding protein that contains 2 RRM domains and is the ortholog of the P34 and P37 proteins from Trypanosoma brucei. The TcNRBD1 protein is expressed in all developmental stages of T. cruzi, and its localization pattern is concentrated at the perinuclear region. TcNRBD1 is associated with polysomes and with the 80S monosomes. Furthermore, sequencing of the mRNAs bound to TcNRBD1 allowed the identification of several transcripts that encode ribosomal proteins. Immunoprecipitation assays followed by mass spectrometry showed that the protein complexes with several ribosomal proteins from both the 40S and 60S subunits. In summary, the results indicate that TcNRBD1 is associated with different parts of the translation process, either by regulating mRNAs that encode ribosomal proteins or by acting in some step of ribosome assembly in T. cruzi.
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Affiliation(s)
- Camila Oliveira
- Instituto Carlos Chagas, Fiocruz-Paraná, Rua Professor Algacyr Munhoz Mader, 3775, Cidade Industrial de Curitiba–CIC, 81350–010, Curitiba, Brasil
| | - Paulo Costa Carvalho
- Instituto Carlos Chagas, Fiocruz-Paraná, Rua Professor Algacyr Munhoz Mader, 3775, Cidade Industrial de Curitiba–CIC, 81350–010, Curitiba, Brasil
| | - Lysangela Ronalte Alves
- Instituto Carlos Chagas, Fiocruz-Paraná, Rua Professor Algacyr Munhoz Mader, 3775, Cidade Industrial de Curitiba–CIC, 81350–010, Curitiba, Brasil
- * E-mail: (SG); (LRA)
| | - Samuel Goldenberg
- Instituto Carlos Chagas, Fiocruz-Paraná, Rua Professor Algacyr Munhoz Mader, 3775, Cidade Industrial de Curitiba–CIC, 81350–010, Curitiba, Brasil
- * E-mail: (SG); (LRA)
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44
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Kiely M, Adams DR, Hayes SL, O'Connor R, Baillie GS, Kiely PA. RACK1 stabilises the activity of PP2A to regulate the transformed phenotype in mammary epithelial cells. Cell Signal 2016; 35:290-300. [PMID: 27600565 DOI: 10.1016/j.cellsig.2016.09.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 09/02/2016] [Accepted: 09/02/2016] [Indexed: 02/04/2023]
Abstract
Conflicting reports implicate the scaffolding protein RACK1 in the progression of breast cancer. RACK1 has been identified as a key regulator downstream of growth factor and adhesion signalling and as a direct binding partner of PP2A. Our objective was to further characterise the interaction between PP2A and RACK1 and to advance our understanding of this complex in breast cancer cells. We examined how the PP2A holoenzyme is assembled on the RACK1 scaffold in MCF-7 cells. We used immobilized peptide arrays representing the entire PP2A-catalytic subunit to identify candidate amino acids on the C subunit of PP2A that might be involved in binding of RACK1. We identified the RACK1 interaction sites on PP2A. Stable cell lines expressing PP2A with FR69/70AA, R214A and Y218F substitutions were generated and it was confirmed that the RACK1/PP2A interaction is essential to stabilise PP2A activity. We used Real-Time Cell Analysis and a series of assays to demonstrate that disruption of the RACK1/PP2A complex also reduces the adhesion, proliferation, migration and invasion of breast cancer cells and plays a role in maintenance of the cancer phenotype. This work has significantly advanced our understanding of the RACK1/PP2A complex and suggests a pro-carcinogenic role for the RACK1/PP2A interaction. This work suggests that approaches to target the RACK1/PP2A complex are a viable option to regulate PP2A activity and identifies a novel potential therapeutic target in the treatment of breast cancer.
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Affiliation(s)
- Maeve Kiely
- Graduate Entry Medical School, Materials and Surface Science Institute and Health Research Institute, University of Limerick, Ireland
| | - David R Adams
- Institute of Chemical Sciences, Heriot-Watt University, Riccarton Campus, Edinburgh EH14AS, UK
| | - Sheri L Hayes
- Graduate Entry Medical School, Materials and Surface Science Institute and Health Research Institute, University of Limerick, Ireland
| | - Rosemary O'Connor
- Cell Biology Laboratory, Department of Biochemistry, BioSciences Institute, University College Cork, Cork, Ireland
| | - George S Baillie
- Institute of Cardiovascular & Medical Science, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Patrick A Kiely
- Graduate Entry Medical School, Materials and Surface Science Institute and Health Research Institute, University of Limerick, Ireland.
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Ribosome-associated Asc1/RACK1 is required for endonucleolytic cleavage induced by stalled ribosome at the 3' end of nonstop mRNA. Sci Rep 2016; 6:28234. [PMID: 27312062 PMCID: PMC4911565 DOI: 10.1038/srep28234] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Accepted: 05/31/2016] [Indexed: 12/21/2022] Open
Abstract
Dom34-Hbs1 stimulates degradation of aberrant mRNAs lacking termination codons by dissociating ribosomes stalled at the 3′ ends, and plays crucial roles in Nonstop Decay (NSD) and No-Go Decay (NGD). In the dom34Δ mutant, nonstop mRNA is degraded by sequential endonucleolytic cleavages induced by a stalled ribosome at the 3′ end. Here, we report that ribosome-associated Asc1/RACK1 is required for the endonucleolytic cleavage of nonstop mRNA by stalled ribosome at the 3′ end of mRNA in dom34Δ mutant cells. Asc1/RACK1 facilitates degradation of truncated GFP-Rz mRNA in the absence of Dom34 and exosome-dependent decay. Asc1/RACK1 is required for the sequential endonucleolytic cleavages by the stalled ribosome in the dom34Δ mutant, depending on its ribosome-binding activity. The levels of peptidyl-tRNA derived from nonstop mRNA were elevated in dom34Δasc1Δ mutant cells, and overproduction of nonstop mRNA inhibited growth of mutant cells. E3 ubiquitin ligase Ltn1 degrades the arrest products from truncated GFP-Rz mRNA in dom34Δ and dom34Δasc1Δ mutant cells, and Asc1/RACK1 represses the levels of substrates for Ltn1-dependent degradation. These indicate that ribosome-associated Asc1/RACK1 facilitates endonucleolytic cleavage of nonstop mRNA by stalled ribosomes and represses the levels of aberrant products even in the absence of Dom34. We propose that Asc1/RACK1 acts as a fail-safe in quality control for nonstop mRNA.
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Thompson MK, Rojas-Duran MF, Gangaramani P, Gilbert WV. The ribosomal protein Asc1/RACK1 is required for efficient translation of short mRNAs. eLife 2016; 5. [PMID: 27117520 PMCID: PMC4848094 DOI: 10.7554/elife.11154] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 03/21/2016] [Indexed: 02/06/2023] Open
Abstract
Translation is a core cellular process carried out by a highly conserved macromolecular machine, the ribosome. There has been remarkable evolutionary adaptation of this machine through the addition of eukaryote-specific ribosomal proteins whose individual effects on ribosome function are largely unknown. Here we show that eukaryote-specific Asc1/RACK1 is required for efficient translation of mRNAs with short open reading frames that show greater than average translational efficiency in diverse eukaryotes. ASC1 mutants in S. cerevisiae display compromised translation of specific functional groups, including cytoplasmic and mitochondrial ribosomal proteins, and display cellular phenotypes consistent with their gene-specific translation defects. Asc1-sensitive mRNAs are preferentially associated with the translational ‘closed loop’ complex comprised of eIF4E, eIF4G, and Pab1, and depletion of eIF4G mimics the translational defects of ASC1 mutants. Together our results reveal a role for Asc1/RACK1 in a length-dependent initiation mechanism optimized for efficient translation of genes with important housekeeping functions. DOI:http://dx.doi.org/10.7554/eLife.11154.001 Ribosomes are structures within cells that are responsible for making proteins. Molecules called messenger RNAs (or mRNAs), which contain genetic information derived from the DNA of a gene, pass through ribosomes that then “translate” that information to build proteins. Although all living cells contain ribosomes, the protein building blocks that make up the structure of the ribosome are not the same in all species. Furthermore, the exact roles that each building block plays during translation are not known. The ribosomes of plants, animals, and budding yeast contain the same protein, known as Asc1 in budding yeast and RACK1 in plants and animals. Thompson et al. have now explored the role of Asc1 in yeast cells by measuring translation in the absence of Asc1 using a technique called ribosome footprint profiling. This analysis revealed that cells lacking Asc1 translate fewer short mRNA molecules than normal cells. Short mRNAs encode small proteins that tend to play important ‘housekeeping’ roles in the cell — by forming the structural building blocks of ribosomes, for example. It has been observed previously that short mRNAs are translated at a higher rate than longer mRNAs on average, although the reasons behind this bias are still mysterious. The findings of Thompson et al. suggest that the ribosome itself may discriminate between short and long mRNAs and that the Asc1 protein is involved in calibrating the ribosome’s preference for short mRNAs. Cells need differing amounts of small proteins in different growth conditions. It will therefore be interesting to investigate whether mRNA length discrimination can be regulated by Asc1 and/or other components of the ribosome to tune gene expression to the environment. DOI:http://dx.doi.org/10.7554/eLife.11154.002
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Affiliation(s)
- Mary K Thompson
- Department of Biology, Massachusetts Institute of Technology, Cambridge, United States
| | - Maria F Rojas-Duran
- Department of Biology, Massachusetts Institute of Technology, Cambridge, United States
| | - Paritosh Gangaramani
- Department of Biology, Massachusetts Institute of Technology, Cambridge, United States
| | - Wendy V Gilbert
- Department of Biology, Massachusetts Institute of Technology, Cambridge, United States
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Marubashi S, Ohbayashi N, Fukuda M. A Varp-Binding Protein, RACK1, Regulates Dendrite Outgrowth through Stabilization of Varp Protein in Mouse Melanocytes. J Invest Dermatol 2016; 136:1672-1680. [PMID: 27066885 DOI: 10.1016/j.jid.2016.03.034] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Revised: 03/18/2016] [Accepted: 03/22/2016] [Indexed: 01/29/2023]
Abstract
Varp (VPS9-ankyrin repeat protein) in melanocytes is thought to function as a key player in the pigmentation of mammals. Varp regulates two different melanocyte functions: (i) transport of melanogenic enzymes to melanosomes by functioning as a Rab32/38 effector and (ii) promotion of dendrite outgrowth by functioning as a Rab21-guanine nucleotide exchange factor. The Varp protein level has recently been shown to be negatively regulated by proteasomal degradation through interaction of the ankyrin repeat 2 (ANKR2) domain of Varp with Rab40C. However, the molecular mechanisms by which Varp escapes from Rab40C and retains its own expression level remain completely unknown. Here, we identified RACK1 (receptor of activated protein kinase C 1) as a Varp-ANKR2 binding partner and investigated its involvement in Varp stabilization in mouse melanocytes. The results showed that knockdown of endogenous RACK1 in melanocytes caused dramatic reduction of the Varp protein level and inhibition of dendrite outgrowth, and intriguingly, overexpression of RACK1 inhibited the interaction between Varp and Rab40C and counteracted the negative effect of Rab40C on dendrite outgrowth. These findings indicated that RACK1 competes with Rab40C for binding to the ANKR2 domain of Varp and regulates dendrite outgrowth through stabilization of Varp in mouse melanocytes.
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Affiliation(s)
- Soujiro Marubashi
- Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Aobayama, Aoba-ku, Sendai, Miyagi 980-8578, Japan
| | - Norihiko Ohbayashi
- Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Aobayama, Aoba-ku, Sendai, Miyagi 980-8578, Japan; Department of Physiological Chemistry, Faculty of Medicine and Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
| | - Mitsunori Fukuda
- Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Aobayama, Aoba-ku, Sendai, Miyagi 980-8578, Japan.
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48
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Gallo S, Manfrini N. Working hard at the nexus between cell signaling and the ribosomal machinery: An insight into the roles of RACK1 in translational regulation. ACTA ACUST UNITED AC 2015; 3:e1120382. [PMID: 26824030 DOI: 10.1080/21690731.2015.1120382] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Revised: 10/19/2015] [Accepted: 11/09/2015] [Indexed: 02/08/2023]
Abstract
RACK1 is a ribosome-associated protein which functions as a receptor for activated PKCs. It also acts as a scaffold for many other proteins involved in diverse signaling pathways, e.g. Src, JNK, PDE4D and FAK signaling. With such a broad interactome, RACK1 has been suggested to function as a linker between cell signaling and the translation machinery. Accordingly, RACK1 modulates translation at different levels in several model organisms. For instance, it regulates ribosome stalling and mRNA quality control in yeasts and promotes translation efficiency downstream of specific cellular stimuli in mammals. However, the molecular mechanism by which RACK1 exerts these roles is widely uncharacterized. Moreover, the full list of ribosome-recruited RACK1 interactors still needs characterization. Here we discuss in vivo and in vitro findings to better delineate the roles of RACK1 in regulating ribosome function and translation.
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Affiliation(s)
- Simone Gallo
- Molecular Histology and Cell Growth Unit; National Institute of Molecular Genetics - INGM "Romeo and Enrica Invernizzi" ; Milan, Italy
| | - Nicola Manfrini
- Molecular Histology and Cell Growth Unit; National Institute of Molecular Genetics - INGM "Romeo and Enrica Invernizzi" ; Milan, Italy
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49
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Shi Z, Barna M. Translating the genome in time and space: specialized ribosomes, RNA regulons, and RNA-binding proteins. Annu Rev Cell Dev Biol 2015; 31:31-54. [PMID: 26443190 DOI: 10.1146/annurev-cellbio-100814-125346] [Citation(s) in RCA: 143] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A central question in cell and developmental biology is how the information encoded in the genome is differentially interpreted to generate a diverse array of cell types. A growing body of research on posttranscriptional gene regulation is revealing that both global protein synthesis rates and the translation of specific mRNAs are highly specialized in different cell types. How this exquisite translational regulation is achieved is the focus of this review. Two levels of regulation are discussed: the translation machinery and cis-acting elements within mRNAs. Recent evidence shows that the ribosome itself directs how the genome is translated in time and space and reveals surprising functional specificity in individual components of the core translation machinery. We are also just beginning to appreciate the rich regulatory information embedded in the untranslated regions of mRNAs, which direct the selective translation of transcripts. These hidden RNA regulons may interface with a myriad of RNA-binding proteins and specialized translation machinery to provide an additional layer of regulation to how transcripts are spatiotemporally expressed. Understanding this largely unexplored world of translational codes hardwired in the core translation machinery is an exciting new research frontier fundamental to our understanding of gene regulation, organismal development, and evolution.
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Affiliation(s)
- Zhen Shi
- Department of Developmental Biology and Department of Genetics, Stanford University, Stanford, California 94305;
| | - Maria Barna
- Department of Developmental Biology and Department of Genetics, Stanford University, Stanford, California 94305;
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50
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Brina D, Miluzio A, Ricciardi S, Clarke K, Davidsen PK, Viero G, Tebaldi T, Offenhäuser N, Rozman J, Rathkolb B, Neschen S, Klingenspor M, Wolf E, Gailus-Durner V, Fuchs H, Hrabe de Angelis M, Quattrone A, Falciani F, Biffo S. eIF6 coordinates insulin sensitivity and lipid metabolism by coupling translation to transcription. Nat Commun 2015; 6:8261. [PMID: 26383020 PMCID: PMC4595657 DOI: 10.1038/ncomms9261] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 08/04/2015] [Indexed: 02/07/2023] Open
Abstract
Insulin regulates glycaemia, lipogenesis and increases mRNA translation. Cells with reduced eukaryotic initiation factor 6 (eIF6) do not increase translation in response to insulin. The role of insulin-regulated translation is unknown. Here we show that reduction of insulin-regulated translation in mice heterozygous for eIF6 results in normal glycaemia, but less blood cholesterol and triglycerides. eIF6 controls fatty acid synthesis and glycolysis in a cell autonomous fashion. eIF6 acts by exerting translational control of adipogenic transcription factors like C/EBPβ, C/EBPδ and ATF4 that have G/C rich or uORF sequences in their 5' UTR. The outcome of the translational activation by eIF6 is a reshaping of gene expression with increased levels of lipogenic and glycolytic enzymes. Finally, eIF6 levels modulate histone acetylation and amounts of rate-limiting fatty acid synthase (Fasn) mRNA. Since obesity, type 2 diabetes, and cancer require a Fasn-driven lipogenic state, we propose that eIF6 could be a therapeutic target for these diseases.
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Affiliation(s)
- Daniela Brina
- INGM, ‘Romeo ed Enrica Invernizzi', 20122 Milano, Italy
| | | | | | - Kim Clarke
- Centre for Computational Biology and Modeling, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Peter K. Davidsen
- Centre for Computational Biology and Modeling, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Gabriella Viero
- Institute of Biophysics, 38123 Trento, Italy
- Centre for Integrative Biology, University of Trento, 38123 Trento, Italy
| | - Toma Tebaldi
- Centre for Integrative Biology, University of Trento, 38123 Trento, Italy
| | | | - Jan Rozman
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Center Munich, 85764 Neuherberg, Germany
| | - Birgit Rathkolb
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Center Munich, 85764 Neuherberg, Germany
- Institute of Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig-Maximilian-University, 81377 Munich, Germany
| | - Susanne Neschen
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Center Munich, 85764 Neuherberg, Germany
| | - Martin Klingenspor
- Else Kröner-Fresenius Center, Technische Universität München, 85354 Freising, Germany
| | - Eckhard Wolf
- Institute of Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig-Maximilian-University, 81377 Munich, Germany
| | - Valerie Gailus-Durner
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Center Munich, 85764 Neuherberg, Germany
| | - Helmut Fuchs
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Center Munich, 85764 Neuherberg, Germany
| | - Martin Hrabe de Angelis
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Center Munich, 85764 Neuherberg, Germany
- Center of Life and Food Sciences Weihenstephan, Technische Universität München, 85354 Freising, Germany
- German Center for Diabetes Research, 85764 Neuherberg, Germany
| | | | - Francesco Falciani
- Centre for Computational Biology and Modeling, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Stefano Biffo
- INGM, ‘Romeo ed Enrica Invernizzi', 20122 Milano, Italy
- Department of Biosciences, University of Milan, 20133 Milan, Italy
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