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Shabek N, Ticchiarelli F, Mao H, Hinds TR, Leyser O, Zheng N. Structural plasticity of D3-D14 ubiquitin ligase in strigolactone signalling. Nature 2018. [PMID: 30464344 DOI: 10.1038/s41586-018-0743-745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The strigolactones, a class of plant hormones, regulate many aspects of plant physiology. In the inhibition of shoot branching, the α/β hydrolase D14-which metabolizes strigolactone-interacts with the F-box protein D3 to ubiquitinate and degrade the transcription repressor D53. Despite the fact that multiple modes of interaction between D14 and strigolactone have recently been determined, how the hydrolase functions with D3 to mediate hormone-dependent D53 ubiquitination remains unknown. Here we show that D3 has a C-terminal α-helix that can switch between two conformational states. The engaged form of this α-helix facilitates the binding of D3 and D14 with a hydrolysed strigolactone intermediate, whereas the dislodged form can recognize unmodified D14 in an open conformation and inhibits its enzymatic activity. The D3 C-terminal α-helix enables D14 to recruit D53 in a strigolactone-dependent manner, which in turn activates the hydrolase. By revealing the structural plasticity of the SCFD3-D14 ubiquitin ligase, our results suggest a mechanism by which the E3 coordinates strigolactone signalling and metabolism.
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Affiliation(s)
- Nitzan Shabek
- Department of Pharmacology, University of Washington, Seattle, WA, USA
- Howard Hughes Medical Institute, University of Washington, Seattle, WA, USA
- Department of Plant Biology, University of California, Davis, Davis, CA, USA
| | | | - Haibin Mao
- Department of Pharmacology, University of Washington, Seattle, WA, USA
- Howard Hughes Medical Institute, University of Washington, Seattle, WA, USA
| | - Thomas R Hinds
- Department of Pharmacology, University of Washington, Seattle, WA, USA
| | - Ottoline Leyser
- The Sainsbury Laboratory, University of Cambridge, Cambridge, UK
| | - Ning Zheng
- Department of Pharmacology, University of Washington, Seattle, WA, USA.
- Howard Hughes Medical Institute, University of Washington, Seattle, WA, USA.
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Arquint C, Cubizolles F, Morand A, Schmidt A, Nigg EA. The SKP1-Cullin-F-box E3 ligase βTrCP and CDK2 cooperate to control STIL abundance and centriole number. Open Biol 2018; 8:170253. [PMID: 29445034 PMCID: PMC5830536 DOI: 10.1098/rsob.170253] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 01/18/2018] [Indexed: 01/14/2023] Open
Abstract
Deregulation of centriole duplication has been implicated in cancer and primary microcephaly. Accordingly, it is important to understand how key centriole duplication factors are regulated. E3 ubiquitin ligases have been implicated in controlling the levels of several duplication factors, including PLK4, STIL and SAS-6, but the precise mechanisms ensuring centriole homeostasis remain to be fully understood. Here, we have combined proteomics approaches with the use of MLN4924, a generic inhibitor of SCF E3 ubiquitin ligases, to monitor changes in the cellular abundance of centriole duplication factors. We identified human STIL as a novel substrate of SCF-βTrCP. The binding of βTrCP depends on a DSG motif within STIL, and serine 395 within this motif is phosphorylated in vivo SCF-βTrCP-mediated degradation of STIL occurs throughout interphase and mutations in the DSG motif causes massive centrosome amplification, attesting to the physiological importance of the pathway. We also uncover a connection between this new pathway and CDK2, whose role in centriole biogenesis remains poorly understood. We show that CDK2 activity protects STIL against SCF-βTrCP-mediated degradation, indicating that CDK2 and SCF-βTrCP cooperate via STIL to control centriole biogenesis.
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Affiliation(s)
- Christian Arquint
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Fabien Cubizolles
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Agathe Morand
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Alexander Schmidt
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Erich A Nigg
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
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3
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Song T, Liang S, Liu J, Zhang T, Yin Y, Geng C, Gao S, Feng Y, Xu H, Guo D, Roberts A, Gu Y, Cang Y. CRL4 antagonizes SCFFbxo7-mediated turnover of cereblon and BK channel to regulate learning and memory. PLoS Genet 2018; 14:e1007165. [PMID: 29370161 PMCID: PMC5800687 DOI: 10.1371/journal.pgen.1007165] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 02/06/2018] [Accepted: 12/25/2017] [Indexed: 12/18/2022] Open
Abstract
Intellectual disability (ID), one of the most common human developmental disorders, can be caused by genetic mutations in Cullin 4B (Cul4B) and cereblon (CRBN). CRBN is a substrate receptor for the Cul4A/B-DDB1 ubiquitin ligase (CRL4) and can target voltage- and calcium-activated BK channel for ER retention. Here we report that ID-associated CRL4CRBN mutations abolish the interaction of the BK channel with CRL4, and redirect the BK channel to the SCFFbxo7 ubiquitin ligase for proteasomal degradation. Glioma cell lines harbouring CRBN mutations record density-dependent decrease of BK currents, which can be restored by blocking Cullin ubiquitin ligase activity. Importantly, mice with neuron-specific deletion of DDB1 or CRBN express reduced BK protein levels in the brain, and exhibit similar impairment in learning and memory, a deficit that can be partially rescued by activating the BK channel. Our results reveal a competitive targeting of the BK channel by two ubiquitin ligases to achieve exquisite control of its stability, and support changes in neuronal excitability as a common pathogenic mechanism underlying CRL4CRBN-associated ID.
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Affiliation(s)
- Tianyu Song
- Life Sciences Institute and Innovation Center for Cell Signalling Network, Zhejiang University, Hangzhou, Zhejiang, China
| | - Shenghui Liang
- Translational and Regenerative Medicine Center, Aston Medical School, Aston University, Birmingham, United Kingdom
| | - Jiye Liu
- Life Sciences Institute and Innovation Center for Cell Signalling Network, Zhejiang University, Hangzhou, Zhejiang, China
| | - Tingyue Zhang
- Life Sciences Institute and Innovation Center for Cell Signalling Network, Zhejiang University, Hangzhou, Zhejiang, China
| | - Yifei Yin
- Life Sciences Institute and Innovation Center for Cell Signalling Network, Zhejiang University, Hangzhou, Zhejiang, China
| | - Chenlu Geng
- Life Sciences Institute and Innovation Center for Cell Signalling Network, Zhejiang University, Hangzhou, Zhejiang, China
| | - Shaobing Gao
- Life Sciences Institute and Innovation Center for Cell Signalling Network, Zhejiang University, Hangzhou, Zhejiang, China
| | - Yan Feng
- Life Sciences Institute and Innovation Center for Cell Signalling Network, Zhejiang University, Hangzhou, Zhejiang, China
| | - Hao Xu
- Laboratory of Molecular Pharmacology, Institute of Molecular Medicine, Peking University, Peking, China
| | - Dongqing Guo
- Laboratory of Molecular Pharmacology, Institute of Molecular Medicine, Peking University, Peking, China
| | - Amanda Roberts
- Molecular and Cellular Neurosciences Department, The Scripps Research Institute, University of California, San Diego, La Jolla, California, United States of America
| | - Yuchun Gu
- Translational and Regenerative Medicine Center, Aston Medical School, Aston University, Birmingham, United Kingdom
- * E-mail: (YC); (YG)
| | - Yong Cang
- Life Sciences Institute and Innovation Center for Cell Signalling Network, Zhejiang University, Hangzhou, Zhejiang, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
- * E-mail: (YC); (YG)
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4
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Liu HW, Chen YJ, Chang YC, Chang SJ. Oligonol, a Low-Molecular Weight Polyphenol Derived from Lychee, Alleviates Muscle Loss in Diabetes by Suppressing Atrogin-1 and MuRF1. Nutrients 2017; 9:nu9091040. [PMID: 28930190 PMCID: PMC5622800 DOI: 10.3390/nu9091040] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2017] [Revised: 09/08/2017] [Accepted: 09/18/2017] [Indexed: 12/19/2022] Open
Abstract
Stimulation of the ubiquitin-proteasome pathway-especially E3 ubiquitin ligases Atrogin-1 and MuRF1-is associated with muscle loss in diabetes. Elevated lipid metabolites impair myogenesis. Oligonol, a low molecular weight polyphenol derived from lychee, exhibited anti-diabetic and anti-obesity properties, suggesting it could be a proper supplement for attenuating muscle loss. Dietary (10 weeks) oligonol supplementation (20 or 200 mg/kg diet) on the skeletal muscle loss was investigated in diabetic db/db mice. Transcription factors NF-κB and FoxO3a involved in regulation of Atrogin-1 and MuRF1 were also investigated. Attenuation of muscle loss by oligonol (both doses) was associated with down-regulation of Atrogin-1 and MuRF1 gene expression. Oligonol supplementation decreased NF-κB expression in the nuclear fraction compared with db/db mice without oligonol supplement. Upregulation of sirtuin1 (SIRT1) expression prevented FoxO3a nuclear localization in db/db mice supplemented with oligonol. Marked increases in AMPKα activity and Ppara mRNA expression leading to lower lipid accumulation by oligonol provided additional benefits for attenuating muscle loss. Oligonol limited palmitate-induced senescent phenotype and cell cycle arrest and suppressed Atrogin-1 and MuRF1 mRNA expression in palmitate-treated C2C12 muscle cells, thus contributing to improving the impaired myotube formation. In conclusion, oligonol-mediated downregulation of Atrogin-1 and MuRF1 gene expression alleviates muscle loss and improves the impaired myotube formation, indicating that oligonol supplementation may be useful for the attenuation of myotube loss.
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Affiliation(s)
- Hung-Wen Liu
- Department of Life Sciences, National Cheng Kung University, No. 1, University Road, Tainan 701, Taiwan.
- Department of Physical Education, National Taiwan Normal University, Taipei 106, Taiwan.
| | - Yen-Ju Chen
- Department of Life Sciences, National Cheng Kung University, No. 1, University Road, Tainan 701, Taiwan.
| | - Yun-Ching Chang
- Department of Life Sciences, National Cheng Kung University, No. 1, University Road, Tainan 701, Taiwan.
| | - Sue-Joan Chang
- Department of Life Sciences, National Cheng Kung University, No. 1, University Road, Tainan 701, Taiwan.
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5
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Kang SH, Lee HA, Kim M, Lee E, Sohn UD, Kim I. Forkhead box O3 plays a role in skeletal muscle atrophy through expression of E3 ubiquitin ligases MuRF-1 and atrogin-1 in Cushing's syndrome. Am J Physiol Endocrinol Metab 2017; 312:E495-E507. [PMID: 28246104 DOI: 10.1152/ajpendo.00389.2016] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 02/21/2017] [Accepted: 02/21/2017] [Indexed: 11/22/2022]
Abstract
Cushing's syndrome is caused by overproduction of the adrenocorticotropic hormone (ACTH), which stimulates the adrenal grand to make cortisol. Skeletal muscle wasting occurs in pathophysiological response to Cushing's syndrome. The forkhead box (FOX) protein family has been implicated as a key regulator of muscle loss under conditions such as diabetes and sepsis. However, the mechanistic role of the FOXO family in ACTH-induced muscle atrophy is not understood. We hypothesized that FOXO3a plays a role in muscle atrophy through expression of the E3 ubiquitin ligases, muscle RING finger protein-1 (MuRF-1), and atrogin-1 in Cushing's syndrome. For establishment of a Cushing's syndrome animal model, Sprague-Dawley rats were implanted with osmotic minipumps containing ACTH (40 ng·kg-1·day-1). ACTH infusion significantly reduced muscle weight. In ACTH-infused rats, MuRF-1, atrogin-1, and FOXO3a were upregulated and the FOXO3a promoter was targeted by the glucocorticoid receptor (GR). Transcriptional activity and expression of FOXO3a were significantly decreased by the GR antagonist RU486. Treatment with RU486 reduced MuRF-1 and atrogin-1 expression in accordance with reduced enrichment of FOXO3a and Pol II on the promoters. Knockdown of FOXO3a prevented dexamethasone-induced MuRF-1 and atrogin-1 expression. These results indicate that FOXO3a plays a role in muscle atrophy through expression of MuRF-1 and atrogin-1 in Cushing's syndrome.
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MESH Headings
- Active Transport, Cell Nucleus/drug effects
- Animals
- Cell Line
- Chromatin Immunoprecipitation
- Cushing Syndrome/metabolism
- Cushing Syndrome/pathology
- Cushing Syndrome/physiopathology
- Disease Models, Animal
- Forkhead Box Protein O3/agonists
- Forkhead Box Protein O3/antagonists & inhibitors
- Forkhead Box Protein O3/genetics
- Forkhead Box Protein O3/metabolism
- Gene Expression Regulation/drug effects
- Genes, Reporter/drug effects
- Glucocorticoids/pharmacology
- Hormone Antagonists/pharmacology
- Male
- Muscle Fibers, Skeletal/drug effects
- Muscle Fibers, Skeletal/metabolism
- Muscle Fibers, Skeletal/pathology
- Muscle Proteins/agonists
- Muscle Proteins/antagonists & inhibitors
- Muscle Proteins/genetics
- Muscle Proteins/metabolism
- Muscle, Skeletal/drug effects
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/pathology
- Muscular Atrophy/etiology
- Promoter Regions, Genetic/drug effects
- RNA Interference
- Rats, Sprague-Dawley
- Receptors, Glucocorticoid/agonists
- Receptors, Glucocorticoid/antagonists & inhibitors
- Receptors, Glucocorticoid/metabolism
- Response Elements/drug effects
- SKP Cullin F-Box Protein Ligases/antagonists & inhibitors
- SKP Cullin F-Box Protein Ligases/genetics
- SKP Cullin F-Box Protein Ligases/metabolism
- Tripartite Motif Proteins/agonists
- Tripartite Motif Proteins/antagonists & inhibitors
- Tripartite Motif Proteins/genetics
- Tripartite Motif Proteins/metabolism
- Ubiquitin-Protein Ligases/antagonists & inhibitors
- Ubiquitin-Protein Ligases/genetics
- Ubiquitin-Protein Ligases/metabolism
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Affiliation(s)
- Seol-Hee Kang
- Department of Pharmacology, Cardiovascular Research Institute, Cell and Matrix Research Institute, Kyungpook National University School of Medicine, Daegu, Republic of Korea
- BK21 Plus Kyungpook National University Biomedical Convergence Program, Kyungpook National University School of Medicine, Daegu, Republic of Korea
| | - Hae-Ahm Lee
- Department of Pharmacology, Cardiovascular Research Institute, Cell and Matrix Research Institute, Kyungpook National University School of Medicine, Daegu, Republic of Korea
| | - Mina Kim
- Department of Pharmacology, Cardiovascular Research Institute, Cell and Matrix Research Institute, Kyungpook National University School of Medicine, Daegu, Republic of Korea
- BK21 Plus Kyungpook National University Biomedical Convergence Program, Kyungpook National University School of Medicine, Daegu, Republic of Korea
| | - Eunjo Lee
- Department of Pharmacology, Cardiovascular Research Institute, Cell and Matrix Research Institute, Kyungpook National University School of Medicine, Daegu, Republic of Korea
- BK21 Plus Kyungpook National University Biomedical Convergence Program, Kyungpook National University School of Medicine, Daegu, Republic of Korea
| | - Uy Dong Sohn
- College of Pharmacy, Chung-Ang University, Seoul, Republic of Korea; and
| | - Inkyeom Kim
- Department of Pharmacology, Cardiovascular Research Institute, Cell and Matrix Research Institute, Kyungpook National University School of Medicine, Daegu, Republic of Korea;
- BK21 Plus Kyungpook National University Biomedical Convergence Program, Kyungpook National University School of Medicine, Daegu, Republic of Korea
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6
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Wu CW, Deonarine A, Przybysz A, Strange K, Choe KP. The Skp1 Homologs SKR-1/2 Are Required for the Caenorhabditis elegans SKN-1 Antioxidant/Detoxification Response Independently of p38 MAPK. PLoS Genet 2016; 12:e1006361. [PMID: 27776126 PMCID: PMC5077136 DOI: 10.1371/journal.pgen.1006361] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 09/13/2016] [Indexed: 01/12/2023] Open
Abstract
SKN-1/Nrf are the primary antioxidant/detoxification response transcription factors in animals and they promote health and longevity in many contexts. SKN-1/Nrf are activated by a remarkably broad-range of natural and synthetic compounds and physiological conditions. Defining the signaling mechanisms that regulate SKN-1/Nrf activation provides insights into how cells coordinate responses to stress. Nrf2 in mammals is regulated in part by the redox sensor repressor protein named Keap1. In C. elegans, the p38 MAPK cascade in the intestine activates SKN-1 during oxidative stress by promoting its nuclear accumulation. Interestingly, we find variation in the kinetics of p38 MAPK activation and tissues with SKN-1 nuclear accumulation among different pro-oxidants that all trigger strong induction of SKN-1 target genes. Using genome-wide RNAi screening, we identify new genes that are required for activation of the core SKN-1 target gene gst-4 during exposure to the natural pro-oxidant juglone. Among 10 putative activators identified in this screen was skr-1/2, highly conserved homologs of yeast and mammalian Skp1, which function to assemble protein complexes. Silencing of skr-1/2 inhibits induction of SKN-1 dependent detoxification genes and reduces resistance to pro-oxidants without decreasing p38 MAPK activation. Global transcriptomics revealed strong correlation between genes that are regulated by SKR-1/2 and SKN-1 indicating a high degree of specificity. We also show that SKR-1/2 functions upstream of the WD40 repeat protein WDR-23, which binds to and inhibits SKN-1. Together, these results identify a novel p38 MAPK independent signaling mechanism that activates SKN-1 via SKR-1/2 and involves WDR-23.
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Affiliation(s)
- Cheng-Wei Wu
- Department of Biology and Genetics Institute, University of Florida, Gainesville, FL 32611, USA
| | - Andrew Deonarine
- Department of Cell Biology, Microbiology, and Molecular Biology, University of South Florida, Tampa, FL, 33620
| | - Aaron Przybysz
- Department of Anesthesiology, University of Michigan, Ann Arbor, MI 48109
| | - Kevin Strange
- The MDI Biological Laboratory, Salisbury Cove, ME 04672
| | - Keith P. Choe
- Department of Biology and Genetics Institute, University of Florida, Gainesville, FL 32611, USA
- * E-mail:
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7
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Chen B, Wu Q, Xiong Z, Ma Y, Yu S, Chen D, Huang S, Dong Y. Adenosine monophosphate-activated protein kinase attenuates cardiomyocyte hypertrophy through regulation of FOXO3a/MAFbx signaling pathway. Acta Biochim Biophys Sin (Shanghai) 2016; 48:827-32. [PMID: 27521792 DOI: 10.1093/abbs/gmw076] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 05/13/2016] [Indexed: 01/12/2023] Open
Abstract
Control of cardiac muscle mass is thought to be determined by a dynamic balance of protein synthesis and degradation. Recent studies have demonstrated that atrophy-related forkhead box O 3a (FOXO3a)/muscle atrophy F-box (MAFbx) signaling pathway plays a central role in the modulation of proteolysis and exert inhibitory effect on cardiomyocyte hypertrophy. In this study, we tested the hypothesis that adenosine monophosphate-activated protein kinase (AMPK) activation attenuates cardiomyocyte hypertrophy by regulating FOXO3a/MAFbx signaling pathway and its downstream protein degradation. The results showed that activation of AMPK with 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR) attenuated cardiomyocyte hypertrophy induced by angiotensin II (Ang II). The antihypertrophic effects of AICAR were blunted by AMPK inhibitor Compound C. In addition, AMPK dramatically increased the activity of transcription factor FOXO3a, up-regulated the expression of its downstream ubiquitin ligase MAFbx, and enhanced cardiomyocyte proteolysis. Meanwhile, the effects of AMPK on protein degradation and cardiomyocyte hypertrophy were blocked after MAFbx was silenced by transfection of cardiomyocytes with MAFbx-siRNA. These results indicate that AMPK plays an important role in the inhibition of cardiomyocyte hypertrophy by activating protein degradation via FOXO3a/MAFbx signaling pathway.
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Affiliation(s)
- Baolin Chen
- Department of Cardiology, The Guizhou Provincial People's Hospital, Guiyang 550002, China
| | - Qiang Wu
- Department of Cardiology, The Guizhou Provincial People's Hospital, Guiyang 550002, China
| | - Zhaojun Xiong
- Department of Cardiology, The Third Affiliated hospital of Sun Yat-Sen University, Guangzhou 510080, China
| | - Yuedong Ma
- Department of Cardiology, The First Affiliated hospital of Sun Yat-Sen University, Guangzhou 510080, China Key Laboratory on Assisted Circulation, Ministry of Health, Guangzhou 510080, China
| | - Sha Yu
- Department of Cardiology, The Guizhou Provincial People's Hospital, Guiyang 550002, China
| | - Dandan Chen
- Department of Cardiology, The Guizhou Provincial People's Hospital, Guiyang 550002, China
| | - Shengwen Huang
- Department of Laboratory, The Guizhou Provincial People's Hospital, Guiyang 550002, China
| | - Yugang Dong
- Department of Cardiology, The First Affiliated hospital of Sun Yat-Sen University, Guangzhou 510080, China Key Laboratory on Assisted Circulation, Ministry of Health, Guangzhou 510080, China
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8
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Bakowski MA, Desjardins CA, Smelkinson MG, Dunbar TA, Lopez-Moyado IF, Rifkin SA, Cuomo CA, Troemel ER. Ubiquitin-mediated response to microsporidia and virus infection in C. elegans. PLoS Pathog 2014; 10:e1004200. [PMID: 24945527 PMCID: PMC4063957 DOI: 10.1371/journal.ppat.1004200] [Citation(s) in RCA: 130] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Accepted: 05/07/2014] [Indexed: 11/18/2022] Open
Abstract
Microsporidia comprise a phylum of over 1400 species of obligate intracellular pathogens that can infect almost all animals, but little is known about the host response to these parasites. Here we use the whole-animal host C. elegans to show an in vivo role for ubiquitin-mediated response to the microsporidian species Nematocida parisii, as well to the Orsay virus, another natural intracellular pathogen of C. elegans. We analyze gene expression of C. elegans in response to N. parisii, and find that it is similar to response to viral infection. Notably, we find an upregulation of SCF ubiquitin ligase components, such as the cullin ortholog cul-6, which we show is important for ubiquitin targeting of N. parisii cells in the intestine. We show that ubiquitylation components, the proteasome, and the autophagy pathway are all important for defense against N. parisii infection. We also find that SCF ligase components like cul-6 promote defense against viral infection, where they have a more robust role than against N. parisii infection. This difference may be due to suppression of the host ubiquitylation system by N. parisii: when N. parisii is crippled by anti-microsporidia drugs, the host can more effectively target pathogen cells for ubiquitylation. Intriguingly, inhibition of the ubiquitin-proteasome system (UPS) increases expression of infection-upregulated SCF ligase components, indicating that a trigger for transcriptional response to intracellular infection by N. parisii and virus may be perturbation of the UPS. Altogether, our results demonstrate an in vivo role for ubiquitin-mediated defense against microsporidian and viral infections in C. elegans.
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Affiliation(s)
- Malina A. Bakowski
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, California, United States of America
| | | | - Margery G. Smelkinson
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, California, United States of America
| | - Tiffany A. Dunbar
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, California, United States of America
| | - Isaac F. Lopez-Moyado
- Bioinformatics and Systems Biology Graduate Program, University of California San Diego, La Jolla, California, United States of America
| | - Scott A. Rifkin
- Bioinformatics and Systems Biology Graduate Program, University of California San Diego, La Jolla, California, United States of America
- Division of Biological Sciences, Section of Ecology, Behavior, and Evolution University of California San Diego, La Jolla, California, United States of America
| | - Christina A. Cuomo
- The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
| | - Emily R. Troemel
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, California, United States of America
- * E-mail:
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9
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Zhao Y, Sun Y. Targeting the mTOR-DEPTOR pathway by CRL E3 ubiquitin ligases: therapeutic application. Neoplasia 2012; 14:360-7. [PMID: 22745582 PMCID: PMC3384423 DOI: 10.1593/neo.12532] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2012] [Revised: 04/10/2012] [Accepted: 04/12/2012] [Indexed: 12/16/2022]
Abstract
The mammalian target of rapamycin (mTOR), an evolutionarily conserved serine/threonine protein kinase, integrates both intracellular and extracellular signals and serves as a central regulator of cell metabolism, growth, proliferation, survival, and autophagy. The mTOR pathway is frequently activated in many human cancers, mainly resulting from alterations in the upstream regulators, such as phosphoinositide 3-kinase (PI3K)/AKT activation, PTEN loss or dysregulation of mTOR-negative regulators (e.g., TSC1/2), leading to uncontrolled proliferation. Thus, inhibiting the PI3K/AKT/mTOR pathways is widely considered as an effective approach for targeted cancer therapy. Recently, we and others found that DEPTOR, a naturally occurring inhibitor of both mTORC1 and mTORC2, was degraded by SCF (Skp1-Cullin-F box proteins) E3 ubiquitin ligase, the founding member of cullin-RING-ligases (CRLs), resulting in mTOR activation and cell proliferation. In addition to DEPTOR, previous studies have demonstrated that several other negative regulators of mTOR pathway are also substrates of CRL/SCF E3s. Thus, targeting CRL/SCF E3s is expected to cause the accumulation of these mTOR signal inhibitors to effectively block the mTOR pathway. In this review, we will discuss mTOR signaling pathway, how DEPTOR regulates mTOR/AKT axis, thus acting as a tumor suppressor or oncogene in some cases, how DEPTOR is ubiquitinated and degraded by SCF(β-TrCP) E3, and how MLN4924, a small-molecule indirect inhibitor of CRL/SCF E3 ligases through blocking cullin neddylation, might be useful as a novel approach of mTOR pathway targeting for cancer therapy.
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Affiliation(s)
- Yongchao Zhao
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, University of Michigan, Ann Arbor, MI 48109, USA
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10
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Johnston JA. Ubiquitin Drug Discovery and Diagnostics Conference - targeting E3 ligases. IDrugs 2010; 13:695-697. [PMID: 20878590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The Ubiquitin Drug Discovery and Diagnostics Conference, held in Philadelphia, included topics covering the role of E3 ligases in disease. This conference report highlights selected presentations on E3-E2 ligase interactions, the SCF cyclin F ubiquitin ligase complex, and targeting HectH9 and KF-1 E3 ligases. Pharmaceutical research discussed includes E3 programs from Progenra and efforts to modulate the Parkin ligase at Elan Pharmaceuticals.
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Affiliation(s)
- Jennifer A Johnston
- Elan Pharmaceuticals, 800 Gateway Boulevard, South San Francisco, CA 94080-7021, USA.
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11
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Abstract
Macrophage infiltration and inflammatory cytokines are powerful drivers of tumorigenesis and metastasis. Wu et al., in this issue of Cancer Cell, show that TNFalpha-dependent NFkappaB activation induces COP9 signalosome-mediated inhibition of GSK3beta and the SCF(beta-TRCP) ubiquitin ligase, thus leading to stabilization of the transcription factor Snail and promoting cell migration and metastasis.
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Affiliation(s)
- Chih-Cheng Yang
- Signal Transduction Program, Burnham Institute for Medical Research, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA
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12
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Wu Y, Deng J, Rychahou PG, Qiu S, Evers BM, Zhou BP. Stabilization of snail by NF-kappaB is required for inflammation-induced cell migration and invasion. Cancer Cell 2009; 15:416-28. [PMID: 19411070 PMCID: PMC2881229 DOI: 10.1016/j.ccr.2009.03.016] [Citation(s) in RCA: 624] [Impact Index Per Article: 41.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2008] [Revised: 09/11/2008] [Accepted: 03/12/2009] [Indexed: 12/22/2022]
Abstract
The increased motility and invasiveness of tumor cells are reminiscent of epithelial-mesenchymal transition (EMT), which occurs during embryonic development, wound healing, and metastasis. In this study, we found that Snail is stabilized by the inflammatory cytokine TNFalpha through the activation of the NF-kappaB pathway. We demonstrated that NF-kappaB is required for the induction of COP9 signalosome 2 (CSN2), which, in turn, blocks the ubiquitination and degradation of Snail. Furthermore, we showed that the expression of Snail correlated with the activation of NF-kappaB in cancer cell lines and metastatic tumor samples. Knockdown of Snail expression inhibited cell migration and invasion induced by inflammatory cytokines and suppressed inflammation-mediated breast cancer metastasis. Our study provides a plausible mechanism for inflammation-induced metastasis.
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Affiliation(s)
- Yadi Wu
- Department of Pharmacology and Toxicology, The University of Texas Medical Branch, Galveston, Texas 77555
- Sealy Center for Cancer Cell Biology, The University of Texas Medical Branch, Galveston, Texas 77555
| | - Jiong Deng
- Department of Thoracic/Head and Neck Medical Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030
| | - Piotr G. Rychahou
- Department of Surgery, The University of Texas Medical Branch, Galveston, Texas 77555
| | - Suimin Qiu
- Department of Pathology, The University of Texas Medical Branch, Galveston, Texas 77555
- Sealy Center for Cancer Cell Biology, The University of Texas Medical Branch, Galveston, Texas 77555
| | - B. Mark Evers
- Department of Surgery, The University of Texas Medical Branch, Galveston, Texas 77555
- Sealy Center for Cancer Cell Biology, The University of Texas Medical Branch, Galveston, Texas 77555
| | - Binhua P. Zhou
- Department of Pharmacology and Toxicology, The University of Texas Medical Branch, Galveston, Texas 77555
- Sealy Center for Cancer Cell Biology, The University of Texas Medical Branch, Galveston, Texas 77555
- To whom correspondence should be addressed. Tel.: 409-747-1963; Fax: 409-747-1938;
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13
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Lagirand-Cantaloube J, Cornille K, Csibi A, Batonnet-Pichon S, Leibovitch MP, Leibovitch SA. Inhibition of atrogin-1/MAFbx mediated MyoD proteolysis prevents skeletal muscle atrophy in vivo. PLoS One 2009; 4:e4973. [PMID: 19319192 PMCID: PMC2656614 DOI: 10.1371/journal.pone.0004973] [Citation(s) in RCA: 146] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2008] [Accepted: 02/27/2009] [Indexed: 11/19/2022] Open
Abstract
Ubiquitin ligase Atrogin1/Muscle Atrophy F-box (MAFbx) up-regulation is required for skeletal muscle atrophy but substrates and function during the atrophic process are poorly known. The transcription factor MyoD controls myogenic stem cell function and differentiation, and seems necessary to maintain the differentiated phenotype of adult fast skeletal muscle fibres. We previously showed that MAFbx mediates MyoD proteolysis in vitro. Here we present evidence that MAFbx targets MyoD for degradation in several models of skeletal muscle atrophy. In cultured myotubes undergoing atrophy, MAFbx expression increases, leading to a cytoplasmic-nuclear shuttling of MAFbx and a selective suppression of MyoD. Conversely, transfection of myotubes with sh-RNA-mediated MAFbx gene silencing (shRNAi) inhibited MyoD proteolysis linked to atrophy. Furthermore, overexpression of a mutant MyoDK133R lacking MAFbx-mediated ubiquitination prevents atrophy of mouse primary myotubes and skeletal muscle fibres in vivo. Regarding the complex role of MyoD in adult skeletal muscle plasticity and homeostasis, its rapid suppression by MAFbx seems to be a major event leading to skeletal muscle wasting. Our results point out MyoD as the second MAFbx skeletal muscle target by which powerful therapies could be developed.
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Affiliation(s)
- Julie Lagirand-Cantaloube
- Laboratoire de Génomique Fonctionnelle et Myogenèse, UMR866 Différenciation Cellulaire et Croissance, INRA UM II, Campus INRA/SupAgro, Montpellier, France
| | - Karen Cornille
- Laboratoire de Génomique Fonctionnelle et Myogenèse, UMR866 Différenciation Cellulaire et Croissance, INRA UM II, Campus INRA/SupAgro, Montpellier, France
| | - Alfredo Csibi
- Laboratoire de Génomique Fonctionnelle et Myogenèse, UMR866 Différenciation Cellulaire et Croissance, INRA UM II, Campus INRA/SupAgro, Montpellier, France
| | | | - Marie Pierre Leibovitch
- Laboratoire de Génomique Fonctionnelle et Myogenèse, UMR866 Différenciation Cellulaire et Croissance, INRA UM II, Campus INRA/SupAgro, Montpellier, France
| | - Serge A. Leibovitch
- Laboratoire de Génomique Fonctionnelle et Myogenèse, UMR866 Différenciation Cellulaire et Croissance, INRA UM II, Campus INRA/SupAgro, Montpellier, France
- * E-mail:
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14
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Tobimatsu K, Noguchi T, Hosooka T, Sakai M, Inagaki K, Matsuki Y, Hiramatsu R, Kasuga M. Overexpression of the transcriptional coregulator Cited2 protects against glucocorticoid-induced atrophy of C2C12 myotubes. Biochem Biophys Res Commun 2008; 378:399-403. [PMID: 19032942 DOI: 10.1016/j.bbrc.2008.11.062] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2008] [Accepted: 11/09/2008] [Indexed: 11/19/2022]
Abstract
In patients with various catabolic conditions, glucocorticoid excess induces skeletal muscle wasting by accelerating protein degradation via the ubiquitin-proteasome pathway. Although the transcriptional coactivator p300 has been implicated in this pathological process, regulatory mechanisms and molecular targets of its action remain unclear. Here we show that CREB-binding protein (CBP)/p300-interacting transactivator with ED-rich tail 2 (Cited2), which binds to the cysteine-histidine-rich region 1 of p300 and CBP, regulates muscle mass in vitro. Adenovirus-mediated overexpression of wild-type Cited2 significantly blocked morphological alterations of C2C12 myotubes with a concomitant decrease in myosin heavy chain protein in response to synthetic glucocorticoid dexamethasone, which were attributable to the reduced induction of atrophy-related ubiquitin ligases MuRF1 and MAFbx. These myotube-sparing effects were less pronounced, however, with a carboxyl-terminally truncated mutant of Cited2 that lacked the ability to bind p300. These results suggest that the gain of Cited2 function counteracts glucocorticoid-induced muscle atrophy through inhibition of proteolysis mediated by p300-dependent gene transcription.
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Affiliation(s)
- Kazutoshi Tobimatsu
- Division of Diabetes, Metabolism, and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan
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15
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Abstract
Ubiquitin-mediated proteolysis regulates all aspects of cellular function, and defects in this process are associated with human diseases. The limited number of identified ubiquitin ligase-substrate pairs is a major bottleneck in the ubiquitin field. We established and applied genetic technologies that combine global protein stability (GPS) profiling and genetic perturbation of E3 activity to screen for substrates of the Skp1-cullin-F-box (SCF) ubiquitin ligase in mammalian cells. Among the >350 potential substrates identified, we found most known SCF targets and many previously unknown substrates involved in cell cycle, apoptosis, and signaling pathways. Exploring cell cycle-stage stability, we found that several substrates used the SCF and other E3s in different cell cycle stages. Our results demonstrate the potential of these technologies as general platforms for the global discovery of E3-substrate regulatory networks.
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Affiliation(s)
- Hsueh-Chi Sherry Yen
- Department of Genetics, Center for Genetics and Genomics, Brigham and Women's Hospital, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
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16
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Abstract
Cancers often exhibit high levels of cyclin E expression, and aberrant cyclin E activity causes genomic instability and increased tumorigenesis. Two tumor suppressor pathways protect cells against cyclin E deregulation. The p53 pathway is induced by excess cyclin E in primary cells and opposes cyclin E activity through induction of p21Cip1. In contrast, the Fbw7 pathway targets cyclin E for degradation, and Fbw7 mutations occur commonly in cancers. We investigated the cooperativity of these two pathways in countering cyclin E-induced genomic instability in primary human cells. We find that loss of p53 and Fbw7 synergistically unmasks cyclin E-induced instability. In normal cells, impaired cyclin E degradation produces genome instability, but this is rapidly mitigated by induction of p53 and p21. In contrast, p53 loss allows the high level of cyclin E kinase activity that results from Fbw7 loss to persist and continuously drive genome instability. Moreover, p21 plays a critical role in suppressing cyclin E when Fbw7 is disabled, and in the absence of p21, sustained cyclin E activity induces rapid cell death via apoptosis. These data directly demonstrate the cooperative roles of these Fbw7 and p53 pathways in restraining cyclin E activity and its associated genome instability.
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Affiliation(s)
- A C Minella
- Division of Clinical Research, Fred Hutchinson Cancer Research Center, Seattle, WA 98109-1024, USA
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17
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Dehoux M, Gobier C, Lause P, Bertrand L, Ketelslegers JM, Thissen JP. IGF-I does not prevent myotube atrophy caused by proinflammatory cytokines despite activation of Akt/Foxo and GSK-3beta pathways and inhibition of atrogin-1 mRNA. Am J Physiol Endocrinol Metab 2007; 292:E145-50. [PMID: 16926385 DOI: 10.1152/ajpendo.00085.2006] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Myofibrillar protein loss occurring in catabolic situations is considered to be mediated by the release of proinflammatory cytokines and associated with a decrease in circulating and muscle levels of insulin-like growth factor I (IGF-I). In this paper, we investigated whether the C(2)C(12) myotube atrophy caused in vitro by TNF-alpha/IFN-gamma cytokines might be reversed by exogenous IGF-I. Our results showed that, despite the presence of TNF-alpha/IFN-gamma, IGF-I retained its full ability to induce the phosphorylation of Akt, Foxo3a, and GSK-3beta (respectively, 16-fold, 9-fold, and 2-fold) together with a decrease in atrogin-1 mRNA (-39%, P < 0.001). Although this ubiquitin ligase has been reported to accelerate the degradation of MyoD, a myogenic transcription factor driving the transcription of myosin heavy chain (MHC), IGF-I failed to blunt the reduction of MyoD and MHC caused by TNF-alpha/IFN-gamma. Moreover, IGF-I only very slightly attenuated the myotube atrophy induced by TNF-alpha/IFN-gamma (TNF-alpha/IFN-gamma 15.48 mum alone vs. TNF-alpha/IFN-gamma/IGF-I 16.97 mum, P < 0.001). In conclusion, our data show that IGF-I does not reverse the myotube atrophy induced by TNF-alpha/IFN-gamma despite the phosphorylation of Foxo and GSK-3beta and the downregulation of atrogin-1 mRNA. Our study suggests therefore that factors other than IGF-I decrease are responsible for the muscle atrophy caused by proinflammatory cytokines.
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Affiliation(s)
- Mischaël Dehoux
- Division of Diabetology and Nutrition, Université catholique de Louvain, 54 avenue Hippocrate, B-1200 Brussels, Belgium
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18
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Nishitani H, Sugimoto N, Roukos V, Nakanishi Y, Saijo M, Obuse C, Tsurimoto T, Nakayama KI, Nakayama K, Fujita M, Lygerou Z, Nishimoto T. Two E3 ubiquitin ligases, SCF-Skp2 and DDB1-Cul4, target human Cdt1 for proteolysis. EMBO J 2006; 25:1126-36. [PMID: 16482215 PMCID: PMC1409712 DOI: 10.1038/sj.emboj.7601002] [Citation(s) in RCA: 300] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2005] [Accepted: 01/23/2006] [Indexed: 12/25/2022] Open
Abstract
Replication licensing is carefully regulated to restrict replication to once in a cell cycle. In higher eukaryotes, regulation of the licensing factor Cdt1 by proteolysis and Geminin is essential to prevent re-replication. We show here that the N-terminal 100 amino acids of human Cdt1 are recognized for proteolysis by two distinct E3 ubiquitin ligases during S-G2 phases. Six highly conserved amino acids within the 10 first amino acids of Cdt1 are essential for DDB1-Cul4-mediated proteolysis. This region is also involved in proteolysis following DNA damage. The second E3 is SCF-Skp2, which recognizes the Cy-motif-mediated Cyclin E/A-cyclin-dependent kinase-phosphorylated region. Consistently, in HeLa cells cosilenced of Skp2 and Cul4, Cdt1 remained stable in S-G2 phases. The Cul4-containing E3 is active during ongoing replication, while SCF-Skp2 operates both in S and G2 phases. PCNA binds to Cdt1 through the six conserved N-terminal amino acids. PCNA is essential for Cul4- but not Skp2-directed degradation during DNA replication and following ultraviolet-irradiation. Our data unravel multiple distinct pathways regulating Cdt1 to block re-replication.
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Affiliation(s)
- Hideo Nishitani
- Department of Molecular Biology, Graduate School of Medical Science, Kyushu University, Higashi-ku, Fukuoka, Japan.
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19
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20
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Sacheck JM, Ohtsuka A, McLary SC, Goldberg AL. IGF-I stimulates muscle growth by suppressing protein breakdown and expression of atrophy-related ubiquitin ligases, atrogin-1 and MuRF1. Am J Physiol Endocrinol Metab 2004; 287:E591-601. [PMID: 15100091 DOI: 10.1152/ajpendo.00073.2004] [Citation(s) in RCA: 415] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Muscle atrophy results primarily from accelerated protein degradation and is associated with increased expression of two muscle-specific ubiquitin ligases (E3s): atrogin-1 and muscle ring finger 1 (MuRF1). Glucocorticoids are essential for many types of muscle atrophy, and their effects are opposite to those of insulin-like growth factor I (IGF-I) and insulin, which promote growth. In myotubes, dexamethasone (Dex) inhibited growth and enhanced breakdown of long-lived cell proteins, especially myofibrillar proteins (as measured by 3-methylhistidine release), while also increasing atrogin-1 and MuRF1 mRNA. Conversely, IGF-I suppressed protein degradation and prevented the Dex-induced increase in proteolysis. IGF-I rapidly reduced atrogin-1 expression within 1 h by blocking mRNA synthesis without affecting mRNA degradation, whereas IGF-I decreased MuRF1 mRNA slowly. IGF-I and insulin also blocked Dex induction of these E3s and several other atrophy-related genes ("atrogenes"). Changes in overall proteolysis with Dex and IGF-I correlated tightly with changes in atrogin-1 mRNA content, but not with changes in MuRF1 mRNA. IGF-I activates the phosphatidylinositol 3-kinase (PI3K)-Akt pathway, and inhibition of this pathway [but not the calcineurin-nuclear factor of activated T cell (NFAT) or the MEK-ERK pathway] increased proteolysis and atrogin-1 mRNA expression. Thus an important component of growth stimulation by IGF-I, through the PI3K-Akt pathway, is its ability to rapidly suppress transcription of the atrophy-related E3 atrogin-1 and other atrogenes and degradation of myofibrillar proteins.
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MESH Headings
- Blotting, Northern
- Cells, Cultured
- Dexamethasone/pharmacology
- Enzyme Inhibitors/pharmacology
- Gene Expression Regulation, Enzymologic/drug effects
- Humans
- Hypoglycemic Agents/pharmacology
- Insulin/pharmacology
- Insulin Resistance/physiology
- Insulin-Like Growth Factor I/pharmacology
- Methylhistidines/metabolism
- Muscle Fibers, Skeletal/drug effects
- Muscle Fibers, Skeletal/metabolism
- Muscle Proteins/antagonists & inhibitors
- Muscle Proteins/biosynthesis
- Muscle Proteins/metabolism
- Muscle, Skeletal/drug effects
- Muscle, Skeletal/enzymology
- Muscle, Skeletal/growth & development
- Muscular Atrophy/metabolism
- Myoblasts/drug effects
- Myoblasts/metabolism
- Myofibrils/metabolism
- Phosphoinositide-3 Kinase Inhibitors
- RNA, Messenger/biosynthesis
- Reverse Transcriptase Polymerase Chain Reaction
- SKP Cullin F-Box Protein Ligases/antagonists & inhibitors
- SKP Cullin F-Box Protein Ligases/biosynthesis
- Stimulation, Chemical
- Tripartite Motif Proteins
- Ubiquitin/biosynthesis
- Ubiquitin-Protein Ligases/antagonists & inhibitors
- Ubiquitin-Protein Ligases/biosynthesis
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Affiliation(s)
- Jennifer M Sacheck
- Department of Cell Biology, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA
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