1
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Huang HT, Lumpkin RJ, Tsai RW, Su S, Zhao X, Xiong Y, Chen J, Mageed N, Donovan KA, Fischer ES, Sellers WR. Ubiquitin-specific proximity labeling for the identification of E3 ligase substrates. Nat Chem Biol 2024:10.1038/s41589-024-01590-9. [PMID: 38514884 DOI: 10.1038/s41589-024-01590-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 02/26/2024] [Indexed: 03/23/2024]
Abstract
Protein ubiquitylation controls diverse processes within eukaryotic cells, including protein degradation, and is often dysregulated in disease. Moreover, small-molecule degraders that redirect ubiquitylation activities toward disease targets are an emerging and promising therapeutic class. Over 600 E3 ubiquitin ligases are expressed in humans, but their substrates remain largely elusive, necessitating the development of new methods for their discovery. Here we report the development of E3-substrate tagging by ubiquitin biotinylation (E-STUB), a ubiquitin-specific proximity labeling method that biotinylates ubiquitylated substrates in proximity to an E3 ligase of interest. E-STUB accurately identifies the direct ubiquitylated targets of protein degraders, including collateral targets and ubiquitylation events that do not lead to substrate degradation. It also detects known substrates of E3 ligase CRBN and VHL with high specificity. With the ability to elucidate proximal ubiquitylation events, E-STUB may facilitate the development of proximity-inducing therapeutics and act as a generalizable method for E3-substrate mapping.
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Affiliation(s)
- Hai-Tsang Huang
- Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Ryan J Lumpkin
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | - Ryan W Tsai
- Broad Institute of Harvard and MIT, Cambridge, MA, USA
| | - Shuyao Su
- Broad Institute of Harvard and MIT, Cambridge, MA, USA
| | - Xu Zhao
- Broad Institute of Harvard and MIT, Cambridge, MA, USA
| | - Yuan Xiong
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | - James Chen
- Broad Institute of Harvard and MIT, Cambridge, MA, USA
| | - Nada Mageed
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Katherine A Donovan
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | - Eric S Fischer
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | - William R Sellers
- Broad Institute of Harvard and MIT, Cambridge, MA, USA.
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA, USA.
- Harvard Medical School, Boston, MA, USA.
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2
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Joo HJ, D'Alessandro M, Oh G, Han S, Kim WJ, Chung GE, Jang Y, Lee JB, Lee C, Yang Y. Novel targets of β-TrCP cooperatively accelerate carbohydrate and fatty acid consumption. J Cell Physiol 2024; 239:e31095. [PMID: 37584358 DOI: 10.1002/jcp.31095] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Revised: 06/29/2023] [Accepted: 07/25/2023] [Indexed: 08/17/2023]
Abstract
Cellular energy is primarily produced from glucose and fat through glycolysis and fatty acid oxidation (FAO) followed by the tricarboxylic acid cycle in mitochondria; energy homeostasis is carefully maintained via numerous feedback pathways. In this report, we uncovered a new master regulator of carbohydrate and lipid metabolism. When ubiquitin E3 ligase β-TrCP2 was inducibly knocked out in β-TrCP1 knockout adult mice, the resulting double knockout mice (DKO) lost fat mass rapidly. Biochemical analyses of the tissues and cells from β-TrCP2 KO and DKO mice revealed that glycolysis, FAO, and lipolysis were dramatically upregulated. The absence of β-TrCP2 increased the protein stability of metabolic rate-limiting enzymes including 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFKFB3), adipose triglyceride lipase (ATGL), carnitine palmitoyltransferase 1A (CPT1A), and carnitine/acylcarnitine translocase (CACT). Our data suggest that β-TrCP is a potential regulator for total energy homeostasis by simultaneously controlling glucose and fatty acid metabolism and that targeting β-TrCP could be an effective strategy to treat obesity and other metabolic disorders.
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Affiliation(s)
- Hyun Jeong Joo
- Department of Biological Sciences, Sookmyung Women's University, Seoul, Republic of Korea
- Department of Biomedical Sciences, Florida State University, Tallahassee, Florida, USA
| | - Matthew D'Alessandro
- Department of Biomedical Sciences, Florida State University, Tallahassee, Florida, USA
| | - Gaeun Oh
- Department of Biological Sciences, Sookmyung Women's University, Seoul, Republic of Korea
| | - Sora Han
- Department of Biological Sciences, Sookmyung Women's University, Seoul, Republic of Korea
| | - Woo Jung Kim
- Department of Biological Sciences, Sookmyung Women's University, Seoul, Republic of Korea
| | - Ga Eun Chung
- Department of Biological Sciences, Sookmyung Women's University, Seoul, Republic of Korea
| | - Youjeong Jang
- Department of Biological Sciences, Sookmyung Women's University, Seoul, Republic of Korea
| | - Jung Bok Lee
- Department of Biological Sciences, Sookmyung Women's University, Seoul, Republic of Korea
| | - Choogon Lee
- Department of Biomedical Sciences, Florida State University, Tallahassee, Florida, USA
| | - Young Yang
- Department of Biological Sciences, Sookmyung Women's University, Seoul, Republic of Korea
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3
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Hicks D, Giresh K, Wrischnik LA, Weiser DC. The PPP1R15 Family of eIF2-alpha Phosphatase Targeting Subunits (GADD34 and CReP). Int J Mol Sci 2023; 24:17321. [PMID: 38139150 PMCID: PMC10743859 DOI: 10.3390/ijms242417321] [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: 10/28/2023] [Revised: 12/01/2023] [Accepted: 12/08/2023] [Indexed: 12/24/2023] Open
Abstract
The vertebrate PPP1R15 family consists of the proteins GADD34 (growth arrest and DNA damage-inducible protein 34, the product of the PPP1R15A gene) and CReP (constitutive repressor of eIF2α phosphorylation, the product of the PPP1R15B gene), both of which function as targeting/regulatory subunits for protein phosphatase 1 (PP1) by regulating subcellular localization, modulating substrate specificity and assembling complexes with target proteins. The primary cellular function of these proteins is to facilitate the dephosphorylation of eukaryotic initiation factor 2-alpha (eIF2α) by PP1 during cell stress. In this review, we will provide a comprehensive overview of the cellular function, biochemistry and pharmacology of GADD34 and CReP, starting with a brief introduction of eIF2α phosphorylation via the integrated protein response (ISR). We discuss the roles GADD34 and CReP play as feedback inhibitors of the unfolded protein response (UPR) and highlight the critical function they serve as inhibitors of the PERK-dependent branch, which is particularly important since it can mediate cell survival or cell death, depending on how long the stressful stimuli lasts, and GADD34 and CReP play key roles in fine-tuning this cellular decision. We briefly discuss the roles of GADD34 and CReP homologs in model systems and then focus on what we have learned about their function from knockout mice and human patients, followed by a brief review of several diseases in which GADD34 and CReP have been implicated, including cancer, diabetes and especially neurodegenerative disease. Because of the potential importance of GADD34 and CReP in aspects of human health and disease, we will discuss several pharmacological inhibitors of GADD34 and/or CReP that show promise as treatments and the controversies as to their mechanism of action. This review will finish with a discussion of the biochemical properties of GADD34 and CReP, their regulation and the additional interacting partners that may provide insight into the roles these proteins may play in other cellular pathways. We will conclude with a brief outline of critical areas for future study.
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Affiliation(s)
- Danielle Hicks
- Department of Science, Mathematics and Engineering, Modesto Junior College, Modesto, CA 95350, USA
- Department of Biological Sciences, University of the Pacific, Stockton, CA 95211, USA
| | - Krithika Giresh
- Department of Biological Sciences, University of the Pacific, Stockton, CA 95211, USA
| | - Lisa A. Wrischnik
- Department of Biological Sciences, University of the Pacific, Stockton, CA 95211, USA
| | - Douglas C. Weiser
- Department of Biological Sciences, University of the Pacific, Stockton, CA 95211, USA
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4
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McGillivary RM, Starr DA, Luxton GWG. Building and breaking mechanical bridges between the nucleus and cytoskeleton: Regulation of LINC complex assembly and disassembly. Curr Opin Cell Biol 2023; 85:102260. [PMID: 37857179 PMCID: PMC10859145 DOI: 10.1016/j.ceb.2023.102260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 09/15/2023] [Accepted: 09/20/2023] [Indexed: 10/21/2023]
Abstract
The nucleus is physically coupled to the cytoskeleton through LINC complexes, macromolecular bridges composed of SUN and KASH proteins that span the nuclear envelope. LINC complexes are involved in a wide variety of critical cellular processes. For these processes to occur, cells regulate the composition, assembly, and disassembly of LINC complexes. Here we discuss recent studies on the regulation of the SUN-KASH interaction that forms the core of the LINC complex. These new findings encompass the stages of LINC complex assembly, from the formation of SUN-KASH heterooligomers to higher-order assemblies of LINC complexes. There is also new work on how components of the LINC complex are selectively dismantled, particularly by proteasomal degradation. It is becoming increasingly clear that LINC complexes are subject to multiple layers of regulation.
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Affiliation(s)
| | - Daniel A Starr
- Department of Molecular and Cellular Biology, University of California, Davis, USA.
| | - G W Gant Luxton
- Department of Molecular and Cellular Biology, University of California, Davis, USA.
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5
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Zhang Z, Sie B, Chang A, Leng Y, Nardone C, Timms RT, Elledge SJ. Elucidation of E3 ubiquitin ligase specificity through proteome-wide internal degron mapping. Mol Cell 2023; 83:3377-3392.e6. [PMID: 37738965 PMCID: PMC10594193 DOI: 10.1016/j.molcel.2023.08.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 06/07/2023] [Accepted: 08/17/2023] [Indexed: 09/24/2023]
Abstract
The ubiquitin-proteasome system plays a critical role in biology by regulating protein degradation. Despite their importance, precise recognition specificity is known for a few of the 600 E3s. Here, we establish a two-pronged strategy for identifying and mapping critical residues of internal degrons on a proteome-scale in HEK-293T cells. We employ global protein stability profiling combined with machine learning to identify 15,800 peptides likely to contain sequence-dependent degrons. We combine this with scanning mutagenesis to define critical residues for over 5,000 predicted degrons. Focusing on Cullin-RING ligase degrons, we generated mutational fingerprints for 219 degrons and developed DegronID, a computational algorithm enabling the clustering of degron peptides with similar motifs. CRISPR analysis enabled the discovery of E3-degron pairs, of which we uncovered 16 pairs that revealed extensive degron variability and structural determinants. We provide the visualization of these data on the public DegronID data browser as a resource for future exploration.
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Affiliation(s)
- Zhiqian Zhang
- Division of Genetics, Department of Medicine, Howard Hughes Medical Institute, Brigham and Women's Hospital, Boston, MA 02115, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Brandon Sie
- Division of Genetics, Department of Medicine, Howard Hughes Medical Institute, Brigham and Women's Hospital, Boston, MA 02115, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Aiquan Chang
- Division of Genetics, Department of Medicine, Howard Hughes Medical Institute, Brigham and Women's Hospital, Boston, MA 02115, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Yumei Leng
- Division of Genetics, Department of Medicine, Howard Hughes Medical Institute, Brigham and Women's Hospital, Boston, MA 02115, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Christopher Nardone
- Division of Genetics, Department of Medicine, Howard Hughes Medical Institute, Brigham and Women's Hospital, Boston, MA 02115, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Richard T Timms
- Division of Genetics, Department of Medicine, Howard Hughes Medical Institute, Brigham and Women's Hospital, Boston, MA 02115, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA; Cambridge Institute of Therapeutic Immunology and Infectious Disease, Department of Medicine, University of Cambridge, Puddicombe Way, Cambridge CB2 0AW, UK
| | - Stephen J Elledge
- Division of Genetics, Department of Medicine, Howard Hughes Medical Institute, Brigham and Women's Hospital, Boston, MA 02115, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.
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6
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Lee S, Carrasquillo Rodríguez JW, Merta H, Bahmanyar S. A membrane-sensing mechanism links lipid metabolism to protein degradation at the nuclear envelope. J Cell Biol 2023; 222:e202304026. [PMID: 37382667 PMCID: PMC10309186 DOI: 10.1083/jcb.202304026] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 05/22/2023] [Accepted: 06/02/2023] [Indexed: 06/30/2023] Open
Abstract
Lipid composition determines organelle identity; however, whether the lipid composition of the inner nuclear membrane (INM) domain of the ER contributes to its identity is not known. Here, we show that the INM lipid environment of animal cells is under local control by CTDNEP1, the master regulator of the phosphatidic acid phosphatase lipin 1. Loss of CTDNEP1 reduces association of an INM-specific diacylglycerol (DAG) biosensor and results in a decreased percentage of polyunsaturated containing DAG species. Alterations in DAG metabolism impact the levels of the resident INM protein Sun2, which is under local proteasomal regulation. We identify a lipid-binding amphipathic helix (AH) in the nucleoplasmic domain of Sun2 that prefers membrane packing defects. INM dissociation of the Sun2 AH is linked to its proteasomal degradation. We suggest that direct lipid-protein interactions contribute to sculpting the INM proteome and that INM identity is adaptable to lipid metabolism, which has broad implications on disease mechanisms associated with the nuclear envelope.
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Affiliation(s)
- Shoken Lee
- Department of Molecular Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | | | - Holly Merta
- Department of Molecular Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | - Shirin Bahmanyar
- Department of Molecular Cellular and Developmental Biology, Yale University, New Haven, CT, USA
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7
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Insights in Post-Translational Modifications: Ubiquitin and SUMO. Int J Mol Sci 2022; 23:ijms23063281. [PMID: 35328702 PMCID: PMC8952880 DOI: 10.3390/ijms23063281] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 03/15/2022] [Accepted: 03/16/2022] [Indexed: 12/23/2022] Open
Abstract
Both ubiquitination and SUMOylation are dynamic post-translational modifications that regulate thousands of target proteins to control virtually every cellular process. Unfortunately, the detailed mechanisms of how all these cellular processes are regulated by both modifications remain unclear. Target proteins can be modified by one or several moieties, giving rise to polymers of different morphology. The conjugation cascades of both modifications comprise a few activating and conjugating enzymes but close to thousands of ligating enzymes (E3s) in the case of ubiquitination. As a result, these E3s give substrate specificity and can form polymers on a target protein. Polymers can be quickly modified forming branches or cleaving chains leading the target protein to its cellular fate. The recent development of mass spectrometry(MS) -based approaches has increased the understanding of ubiquitination and SUMOylation by finding essential modified targets in particular signaling pathways. Here, we perform a concise overview comprising from the basic mechanisms of both ubiquitination and SUMOylation to recent MS-based approaches aimed to find specific targets for particular E3 enzymes.
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8
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A comprehensive phenotypic CRISPR-Cas9 screen of the ubiquitin pathway uncovers roles of ubiquitin ligases in mitosis. Mol Cell 2021; 81:1319-1336.e9. [PMID: 33539788 DOI: 10.1016/j.molcel.2021.01.014] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 10/20/2020] [Accepted: 01/11/2021] [Indexed: 12/13/2022]
Abstract
The human ubiquitin proteasome system, composed of over 700 ubiquitin ligases (E3s) and deubiquitinases (DUBs), has been difficult to characterize systematically and phenotypically. We performed chemical-genetic CRISPR-Cas9 screens to identify E3s/DUBs whose loss renders cells sensitive or resistant to 41 compounds targeting a broad range of biological processes, including cell cycle progression, genome stability, metabolism, and vesicular transport. Genes and compounds clustered functionally, with inhibitors of related pathways interacting similarly with E3s/DUBs. Some genes, such as FBXW7, showed interactions with many of the compounds. Others, such as RNF25 and FBXO42, showed interactions primarily with a single compound (methyl methanesulfonate for RNF25) or a set of related compounds (the mitotic cluster for FBXO42). Mutation of several E3s with sensitivity to mitotic inhibitors led to increased aberrant mitoses, suggesting a role for these genes in cell cycle regulation. Our comprehensive CRISPR-Cas9 screen uncovered 466 gene-compound interactions covering 25% of the interrogated E3s/DUBs.
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9
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Islam S, Dutta P, Sahay O, Santra MK. β-TrCP1 facilitates cell cycle checkpoint activation, DNA repair, and cell survival through ablation of β-TrCP2 in response to genotoxic stress. J Biol Chem 2021; 296:100511. [PMID: 33676897 PMCID: PMC8093472 DOI: 10.1016/j.jbc.2021.100511] [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: 09/25/2020] [Revised: 02/24/2021] [Accepted: 03/03/2021] [Indexed: 11/22/2022] Open
Abstract
F-box proteins β-TrCP1 and β-TrCP2 are paralogs present in the human genome. They control several cellular processes including cell cycle and DNA damage signaling. Moreover, it is reported that they facilitate DNA damage-induced accumulation of p53 by directing proteasomal degradation of MDM2, a protein that promotes p53 degradation. However, the individual roles of β-TrCP1 and β-TrCP2 in the genotoxic stress-induced activation of cell cycle checkpoints and DNA damage repair remain largely unknown. Here, using biochemical, molecular biology, flow cytometric, and immunofluorescence techniques, we show that β-TrCP1 and β-TrCP2 communicate during genotoxic stress. We found that expression levels of β-TrCP1 are significantly increased while levels of β-TrCP2 are markedly decreased upon induction of genotoxic stress. Further, our results revealed that DNA damage-induced activation of ATM kinase plays an important role in maintaining the reciprocal expression levels of β-TrCP1 and β-TrCP2 via the phosphorylation of β-TrCP1 at Ser158. Phosphorylated β-TrCP1 potently promotes the proteasomal degradation of β-TrCP2 and MDM2, resulting in the activation of p53. Additionally, β-TrCP1 impedes MDM2 accumulation via abrogation of its lysine 63-linked polyubiquitination by β-TrCP2. Thus, β-TrCP1 helps to arrest cells at the G2/M phase of the cell cycle and promotes DNA repair upon DNA damage through attenuation of β-TrCP2. Collectively, our findings elucidate an intriguing posttranslational regulatory mechanism of these two paralogs under genotoxic stress and revealed β-TrCP1 as a key player in maintaining the genome integrity through the attenuation of β-TrCP2 levels in response to genotoxic stress.
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Affiliation(s)
- Sehbanul Islam
- Molecular Oncology Laboratory, National Centre for Cell Science, Pune, Maharashtra, India; Department of Biotechnology, Savitribai Phule Pune University, Pune, Maharashtra, India
| | - Parul Dutta
- Molecular Oncology Laboratory, National Centre for Cell Science, Pune, Maharashtra, India; Department of Biotechnology, Savitribai Phule Pune University, Pune, Maharashtra, India
| | - Osheen Sahay
- Molecular Oncology Laboratory, National Centre for Cell Science, Pune, Maharashtra, India; Department of Biotechnology, Savitribai Phule Pune University, Pune, Maharashtra, India
| | - Manas Kumar Santra
- Molecular Oncology Laboratory, National Centre for Cell Science, Pune, Maharashtra, India.
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10
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Bi Y, Cui D, Xiong X, Zhao Y. The characteristics and roles of β-TrCP1/2 in carcinogenesis. FEBS J 2020; 288:3351-3374. [PMID: 33021036 DOI: 10.1111/febs.15585] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 09/02/2020] [Accepted: 10/01/2020] [Indexed: 12/11/2022]
Abstract
β-transducin repeat-containing protein (β-TrCP), one of the well-characterized F-box proteins, acts as a substrate receptor and constitutes an active SCFβ-TrCP E3 ligase with a scaffold protein CUL1, a RING protein RBX1, and an adaptor protein SKP1. β-TrCP plays a critical role in the regulation of various physiological and pathological processes, including signal transduction, cell cycle progression, cell migration, DNA damage response, and tumorigenesis, by governing burgeoning amounts of key regulators for ubiquitination and proteasomal degradation. Given that a variety of β-TrCP substrates are well-known oncoproteins and tumor suppressors, and dysregulation of β-TrCP is frequently identified in human cancers, β-TrCP plays a vital role in carcinogenesis. In this review, we first briefly introduce the characteristics of β-TrCP1, β-TrCP2, and SCFβ-TrCP ubiquitin ligase, and then discuss SCFβ-TrCP ubiquitin ligase regulated biological processes by targeting its substrates for degradation. Moreover, we summarize the regulation of β-TrCP1 and β-TrCP2 at multiple layers and further discuss the various roles of β-TrCP1 and β-TrCP2 in human cancer, functioning as either an oncoprotein or a tumor suppressor in a manner dependent of cellular context. Finally, we provide novel insights for future perspectives on the potential of targeting β-TrCP1 and β-TrCP2 for cancer therapy.
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Affiliation(s)
- Yanli Bi
- Key Laboratory of Combined Multi-Organ Transplantation, Ministry of Public Health, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, China
| | - Danrui Cui
- Key Laboratory of Combined Multi-Organ Transplantation, Ministry of Public Health, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, China
| | - Xiufang Xiong
- Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, China.,Cancer Institute of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Yongchao Zhao
- Key Laboratory of Combined Multi-Organ Transplantation, Ministry of Public Health, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, China
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11
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Merkel Cell Polyomavirus Large T Antigen Unique Domain Regulates Its Own Protein Stability and Cell Growth. Viruses 2020; 12:v12091043. [PMID: 32962090 PMCID: PMC7551350 DOI: 10.3390/v12091043] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 09/14/2020] [Accepted: 09/16/2020] [Indexed: 02/07/2023] Open
Abstract
Merkel cell polyomavirus (MCV) is the only known human oncogenic virus in the polyomaviridae family and the etiological agent of most Merkel cell carcinomas (MCC). MCC is an aggressive and highly metastatic skin cancer with a propensity for recurrence and poor prognosis. Large tumor antigen (LT), is an essential oncoprotein for MCV transcription, viral replication, and cancer cell proliferation. MCV LT is a short-lived protein that encodes a unique domain: MCV LT unique regions (MURs). These domains consist of phosphorylation sites that interact with multiple E3 ligases, thus limiting LT expression and consequently, viral replication. In this study, we show that MURs are necessary for regulating LT stability via multiple E3 ligase interactions, resulting in cell growth arrest. While expression of wild-type MCV LT induced a decrease in cellular proliferation, deletion of the MUR domains resulted in increased LT stability and cell proliferation. Conversely, addition of MURs to SV40 LT propagated E3 ligase interactions, which in turn, reduced SV40 LT stability and decreased cell growth activity. Our results demonstrate that compared to other human polyomaviruses (HPyVs), MCV LT has evolved to acquire the MUR domains that are essential for MCV LT autoregulation, potentially leading to viral latency and MCC.
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12
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Kastan JP, Dobrikova EY, Bryant JD, Gromeier M. CReP mediates selective translation initiation at the endoplasmic reticulum. SCIENCE ADVANCES 2020; 6:eaba0745. [PMID: 32537501 PMCID: PMC7269655 DOI: 10.1126/sciadv.aba0745] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Accepted: 03/13/2020] [Indexed: 05/16/2023]
Abstract
Eukaryotic protein synthesis control at multiple levels allows for dynamic, selective responses to diverse conditions, but spatial organization of translation initiation machinery as a regulatory principle has remained largely unexplored. Here we report on a role of constitutive repressor of eIF2α phosphorylation (CReP) in translation of poliovirus and the endoplasmic reticulum (ER)-resident chaperone binding immunoglobulin protein (BiP) at the ER. Functional, proximity-dependent labeling and cell fractionation studies revealed that CReP, through binding eIF2α, anchors translation initiation machinery at the ER and enables local protein synthesis in this compartment. This ER site was protected from the suppression of cytoplasmic protein synthesis by acute stress responses, e.g., phosphorylation of eIF2α(S51) or mTOR blockade. We propose that partitioning of translation initiation machinery at the ER enables cells to maintain active translation during stress conditions associated with global protein synthesis suppression.
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Affiliation(s)
- Jonathan P. Kastan
- Department of Neurosurgery, Duke University Medical Center, NC 27710, USA
| | - Elena Y. Dobrikova
- Department of Neurosurgery, Duke University Medical Center, NC 27710, USA
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13
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Kliza K, Husnjak K. Resolving the Complexity of Ubiquitin Networks. Front Mol Biosci 2020; 7:21. [PMID: 32175328 PMCID: PMC7056813 DOI: 10.3389/fmolb.2020.00021] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 02/04/2020] [Indexed: 12/22/2022] Open
Abstract
Ubiquitination regulates nearly all cellular processes by coordinated activity of ubiquitin writers (E1, E2, and E3 enzymes), erasers (deubiquitinating enzymes) and readers (proteins that recognize ubiquitinated proteins by their ubiquitin-binding domains). By differentially modifying cellular proteome and by recognizing these ubiquitin modifications, ubiquitination machinery tightly regulates execution of specific cellular events in space and time. Dynamic and complex ubiquitin architecture, ranging from monoubiquitination, multiple monoubiquitination, eight different modes of homotypic and numerous types of heterogeneous polyubiquitin linkages, enables highly dynamic and complex regulation of cellular processes. We discuss available tools and approaches to study ubiquitin networks, including methods for the identification and quantification of ubiquitin-modified substrates, as well as approaches to quantify the length, abundance, linkage type and architecture of different ubiquitin chains. Furthermore, we also summarize the available approaches for the discovery of novel ubiquitin readers and ubiquitin-binding domains, as well as approaches to monitor and visualize activity of ubiquitin conjugation and deconjugation machineries. We also discuss benefits, drawbacks and limitations of available techniques, as well as what is still needed for detailed spatiotemporal dissection of cellular ubiquitination networks.
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Affiliation(s)
- Katarzyna Kliza
- Institute of Biochemistry II, Medical Faculty, Goethe University, Frankfurt, Germany
| | - Koraljka Husnjak
- Institute of Biochemistry II, Medical Faculty, Goethe University, Frankfurt, Germany
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14
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Huang XQ, Hao S, Zhou ZQ, Huang B, Fang JY, Tang Y, Zhang JH, Xia JC. The Roles of Ubiquitination Factor E4B (UBE4B) in the Postoperative Prognosis of Patients with Renal Cell Carcinoma and in Renal Tumor Cells Growth and Metastasis. Onco Targets Ther 2020; 13:185-197. [PMID: 32021266 PMCID: PMC6956714 DOI: 10.2147/ott.s229577] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Accepted: 12/24/2019] [Indexed: 12/22/2022] Open
Abstract
Object This study aimed at investigating the clinical significance and biological function of ubiquitination factor E4B (UBE4B) in human renal cell carcinoma (RCC). Methods 19 paired clear cell renal cell carcinoma (ccRCC) tumor samples and the matched neighboring non-tumor samples were used to detect the expression of UBE4B in RCC tumor by Western blotting and RT-qPCR. UBE4B expression was also detected in 151 ccRCC paraffin-embedded tumor samples by using immunohistochemistry. Overall survival (OS) in different UBE4B expression groups were compared with Log rank test. The prognostic value of UBE4B expression in OS was evaluated with the univariate and multivariate Cox regression models. UBE4B was knocked down by small interfering RNA (siRNA) technology, and the effect of UBE4B on cell proliferation, colony formation, metastasis, apoptosis and cell cycle of RCC cells were examined in vitro. Results Both protein and mRNA levels of UBE4B were up-regulated in ccRCC tumor tissues in contrast to the corresponding adjacent nontumor ones. UBE4B expression was positively associated with tumor-node-metastasis (TNM) stage and distant metastasis in ccRCC patients. Survival analyses indicated that low expression of UBE4B was associated with increased OS in ccRCC patients. Functional analyses demonstrated that siRNA silencing of UBE4B expression in SKRC39 and ACHN cells further reduced the growth, motility and invasiveness of RCC cells. Moreover, siRNA silencing of UBE4B in the RCC cell lines did not induce apoptosis, and an increase in the cell population was observed during the G0/G1 phase of the cell cycle. Conclusion UBE4B might act as an oncogene in regulating RCC development. Therefore it could be served as an effective indicator to predict OS and a potential biomarker for targeted therapy of RCC patients.
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Affiliation(s)
- Xu-Qiong Huang
- Huadu District People's Hospital of Guangzhou, Southern Medical University, Guangzhou, Guangdong Province, People's Republic of China
| | - Shuai Hao
- Huadu District People's Hospital of Guangzhou, Southern Medical University, Guangzhou, Guangdong Province, People's Republic of China
| | - Zi-Qi Zhou
- State Key Laboratory of Oncology in Southern China, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong Province, People's Republic of China
| | - Bin Huang
- Huadu District People's Hospital of Guangzhou, Southern Medical University, Guangzhou, Guangdong Province, People's Republic of China
| | - Jia-Ying Fang
- Huadu District People's Hospital of Guangzhou, Southern Medical University, Guangzhou, Guangdong Province, People's Republic of China
| | - Yan Tang
- State Key Laboratory of Oncology in Southern China, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong Province, People's Republic of China
| | - Jian-Hua Zhang
- Department of Health Service Management, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong Province, People's Republic of China
| | - Jian-Chuan Xia
- State Key Laboratory of Oncology in Southern China, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong Province, People's Republic of China
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15
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Abstract
The field of aging research has progressed significantly over the past decades. Exogenously and endogenously inflicted molecular damage ranging from genotoxic to organellar damage drives the aging process. Repair mechanisms and compensatory responses counteract the detrimental consequences of the various damage types. Here, we discuss recent progress in understanding cellular mechanisms and interconnections between signaling pathways that control longevity. We summarize cell-autonomous and non-cell-autonomous mechanisms that impact the cellular and organismal aging process
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Affiliation(s)
- Robert Bayersdorf
- Institute for Genome Stability in Aging and Disease, Medical Faculty, University of Cologne, Cologne, Germany.,Cologne Excellence Cluster for Cellular Stress Responses in Ageing-Associated Diseases (CECAD), Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Björn Schumacher
- Institute for Genome Stability in Aging and Disease, Medical Faculty, University of Cologne, Cologne, Germany.,Cologne Excellence Cluster for Cellular Stress Responses in Ageing-Associated Diseases (CECAD), Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
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16
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Rayner SL, Morsch M, Molloy MP, Shi B, Chung R, Lee A. Using proteomics to identify ubiquitin ligase-substrate pairs: how novel methods may unveil therapeutic targets for neurodegenerative diseases. Cell Mol Life Sci 2019; 76:2499-2510. [PMID: 30919022 PMCID: PMC11105231 DOI: 10.1007/s00018-019-03082-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 03/14/2019] [Accepted: 03/20/2019] [Indexed: 12/13/2022]
Abstract
Ubiquitin ligases play an integral role in fine-tuning signaling cascades necessary for normal cell function. Aberrant regulation of ubiquitin ligases has been implicated in several neurodegenerative diseases, generally, due to mutations within the E3 ligase itself. Several proteomic-based methods have recently emerged to facilitate the rapid identification of ligase-substrate pairs-a previously challenging feat due to the transient nature of ligase-substrate interactions. These novel methods complement standard immunoprecipitations (IPs) and include proximity-dependent biotin identification (BioID), ubiquitin ligase-substrate trapping, tandem ubiquitin-binding entities (TUBEs), and a molecular trapping unit known as the NEDDylator. The implementation of these techniques is expected to facilitate the rapid identification of novel substrates of E3 ubiquitin ligases, a process that is likely to enhance our understanding of neurodegenerative diseases and highlight novel therapeutic targets for the treatment of neurodegenerative diseases.
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Affiliation(s)
- Stephanie L Rayner
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, 2 Technology Place, Macquarie Park, Sydney, NSW, 2109, Australia
| | - Marco Morsch
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, 2 Technology Place, Macquarie Park, Sydney, NSW, 2109, Australia
| | - Mark P Molloy
- Faculty of Medicine and Health, Sydney School of Medicine, Royal North Shore Hospital, Pacific Hwy, St Leonards, Sydney, NSW, 2065, Australia
| | - Bingyang Shi
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, 2 Technology Place, Macquarie Park, Sydney, NSW, 2109, Australia
| | - Roger Chung
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, 2 Technology Place, Macquarie Park, Sydney, NSW, 2109, Australia
| | - Albert Lee
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, 2 Technology Place, Macquarie Park, Sydney, NSW, 2109, Australia.
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17
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Brautigan DL, Shenolikar S. Protein Serine/Threonine Phosphatases: Keys to Unlocking Regulators and Substrates. Annu Rev Biochem 2019; 87:921-964. [PMID: 29925267 DOI: 10.1146/annurev-biochem-062917-012332] [Citation(s) in RCA: 112] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Protein serine/threonine phosphatases (PPPs) are ancient enzymes, with distinct types conserved across eukaryotic evolution. PPPs are segregated into types primarily on the basis of the unique interactions of PPP catalytic subunits with regulatory proteins. The resulting holoenzymes dock substrates distal to the active site to enhance specificity. This review focuses on the subunit and substrate interactions for PPP that depend on short linear motifs. Insights about these motifs from structures of holoenzymes open new opportunities for computational biology approaches to elucidate PPP networks. There is an expanding knowledge base of posttranslational modifications of PPP catalytic and regulatory subunits, as well as of their substrates, including phosphorylation, acetylation, and ubiquitination. Cross talk between these posttranslational modifications creates PPP-based signaling. Knowledge of PPP complexes, signaling clusters, as well as how PPPs communicate with each other in response to cellular signals should unlock the doors to PPP networks and signaling "clouds" that orchestrate and coordinate different aspects of cell physiology.
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Affiliation(s)
- David L Brautigan
- Center for Cell Signaling and Department of Microbiology, Immunology and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA;
| | - Shirish Shenolikar
- Signature Research Programs in Cardiovascular and Metabolic Disorders and Neuroscience and Behavioral Disorders, Duke-NUS Medical School, Singapore 169857
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18
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Xu X, Krumm C, So JS, Bare CJ, Holman C, Gromada J, Cohen DE, Lee AH. Preemptive Activation of the Integrated Stress Response Protects Mice From Diet-Induced Obesity and Insulin Resistance by Fibroblast Growth Factor 21 Induction. Hepatology 2018; 68:2167-2181. [PMID: 29698569 PMCID: PMC6203669 DOI: 10.1002/hep.30060] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Accepted: 04/23/2018] [Indexed: 12/11/2022]
Abstract
Integrated stress response (ISR) is a signaling system in which phosphorylation of eukaryotic translation initiation factor 2α (eIF2α) by stress-specific kinases and subsequent activation of activation transcription factor (ATF) 4 help restore cellular homeostasis following exposure to environmental stresses. ISR activation has been observed in metabolic diseases, including hepatic steatosis (HS), steatohepatitis (SH), and insulin resistance (IR), but it remains unclear whether ISR contributes to disease pathogenesis or represents an innate defense mechanism against metabolic stresses. Constitutive repressor of eIF2α phosphorylation (CReP) is a critical regulatory subunit of the eIF2α phosphatase complex. Here, we show that CReP ablation causes constitutive eIF2α phosphorylation in the liver, which leads to activation of the ATF4 transcriptional program including increased fibroblast growth factor 21 (FGF21) production. Liver-specific CReP knockout (CRePLKO ) mice exhibited marked browning of white adipose tissue (WAT) and increased energy expenditure and insulin sensitivity in an FGF21-dependent manner. Furthermore, CRePLKO mice were protected from high-fat diet (HFD)-induced obesity, HS, and IR. Acute CReP ablation in liver of HFD-induced obese mice also reduced adiposity and improved glucose homeostasis. Conclusion: These data suggest that CReP abundance is a critical determinant for eIF2α phosphorylation and ensuing ISR activation in the liver. Constitutive ISR activation in the liver induces FGF21 and confers protection from HFD-induced adiposity, IR, and HS in mice. Augmenting hepatic ISR may represent a therapeutic approach to treat metabolic disorders.
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Affiliation(s)
- Xu Xu
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY 10065,Division of Gastroenterology and Hepatology, Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medicine, New York, NY 10021, USA
| | - Christopher Krumm
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY 10065,Division of Gastroenterology and Hepatology, Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medicine, New York, NY 10021, USA
| | - Jae-Seon So
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY 10065,Department of Medical Biotechnology, Dongguk University Gyeongju, Gyeongju-si, Korea
| | - Curtis J. Bare
- Division of Gastroenterology and Hepatology, Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medicine, New York, NY 10021, USA
| | - Corey Holman
- Division of Gastroenterology and Hepatology, Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medicine, New York, NY 10021, USA
| | - Jesper Gromada
- Regeneron Pharmaceuticals, Tarrytown, New York 10591, USA
| | - David E. Cohen
- Division of Gastroenterology and Hepatology, Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medicine, New York, NY 10021, USA
| | - Ann-Hwee Lee
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY 10065,Regeneron Pharmaceuticals, Tarrytown, New York 10591, USA,Correspondence to: Ann-Hwee Lee, PhD, Regeneron Pharmaceuticals, 777 Old Saw Mill River Road, Tarrytown, NY 10591, Phone: 914-847-1997,
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19
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Hülsmann J, Kravic B, Weith M, Gstaiger M, Aebersold R, Collins BC, Meyer H. AP-SWATH Reveals Direct Involvement of VCP/p97 in Integrated Stress Response Signaling Through Facilitating CReP/PPP1R15B Degradation. Mol Cell Proteomics 2018; 17:1295-1307. [PMID: 29599191 DOI: 10.1074/mcp.ra117.000471] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 03/07/2018] [Indexed: 12/27/2022] Open
Abstract
The ubiquitin-directed AAA-ATPase VCP/p97 facilitates degradation of damaged or misfolded proteins in diverse cellular stress response pathways. Resolving the complexity of its interactions with partner and substrate proteins and understanding its links to stress signaling is therefore a major challenge. Here, we used affinity-purification SWATH mass spectrometry (AP-SWATH) to identify proteins that specifically interact with the substrate-trapping mutant, p97-E578Q. AP-SWATH identified differential interactions over a large detection range from abundant p97 cofactors to pathway-specific partners and individual ligases such as RNF185 and MUL1 that were trapped in p97-E578Q complexes. In addition, we identified various substrate proteins and candidates including the PP1 regulator CReP/PPP1R15B that dephosphorylates eIF2α and thus counteracts attenuation of translation by stress-kinases. We provide evidence that p97 with its Ufd1-Npl4 adapter ensures rapid constitutive turnover and balanced levels of CReP in unperturbed cells. Moreover, we show that p97-mediated degradation, together with a reduction in CReP synthesis, is essential for timely stress-induced reduction of CReP levels and, consequently, for robust eIF2α phosphorylation to enforce the stress response. Thus, our results demonstrate that p97 not only facilitates bulk degradation of misfolded proteins upon stress, but also directly modulates the integrated stress response at the level of signaling.
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Affiliation(s)
- Julia Hülsmann
- From the ‡Molecular Biology I, Centre for Medical Biotechnology, Faculty of Biology, University of Duisburg-Essen, 45141 Essen, Germany
| | - Bojana Kravic
- From the ‡Molecular Biology I, Centre for Medical Biotechnology, Faculty of Biology, University of Duisburg-Essen, 45141 Essen, Germany
| | - Matthias Weith
- From the ‡Molecular Biology I, Centre for Medical Biotechnology, Faculty of Biology, University of Duisburg-Essen, 45141 Essen, Germany
| | - Matthias Gstaiger
- §Department of Biology, Institute of Molecular Systems Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Ruedi Aebersold
- §Department of Biology, Institute of Molecular Systems Biology, ETH Zurich, 8093 Zurich, Switzerland.,¶Faculty of Science, University of Zurich, Zurich, Switzerland
| | - Ben C Collins
- §Department of Biology, Institute of Molecular Systems Biology, ETH Zurich, 8093 Zurich, Switzerland;
| | - Hemmo Meyer
- From the ‡Molecular Biology I, Centre for Medical Biotechnology, Faculty of Biology, University of Duisburg-Essen, 45141 Essen, Germany;
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20
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Lead discovery and chemical biology approaches targeting the ubiquitin proteasome system. Bioorg Med Chem Lett 2017; 27:4589-4596. [DOI: 10.1016/j.bmcl.2017.08.058] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 08/24/2017] [Accepted: 08/28/2017] [Indexed: 12/26/2022]
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21
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Loll-Krippleber R, Brown GW. P-body proteins regulate transcriptional rewiring to promote DNA replication stress resistance. Nat Commun 2017; 8:558. [PMID: 28916784 PMCID: PMC5601920 DOI: 10.1038/s41467-017-00632-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Accepted: 07/12/2017] [Indexed: 12/12/2022] Open
Abstract
mRNA-processing (P-) bodies are cytoplasmic granules that form in eukaryotic cells in response to numerous stresses to serve as sites of degradation and storage of mRNAs. Functional P-bodies are critical for the DNA replication stress response in yeast, yet the repertoire of P-body targets and the mechanisms by which P-bodies promote replication stress resistance are unknown. In this study we identify the complete complement of mRNA targets of P-bodies during replication stress induced by hydroxyurea treatment. The key P-body protein Lsm1 controls the abundance of HHT1, ACF4, ARL3, TMA16, RRS1 and YOX1 mRNAs to prevent their toxic accumulation during replication stress. Accumulation of YOX1 mRNA causes aberrant downregulation of a network of genes critical for DNA replication stress resistance and leads to toxic acetaldehyde accumulation. Our data reveal the scope and the targets of regulation by P-body proteins during the DNA replication stress response. P-bodies form in response to stress and act as sites of mRNA storage and degradation. Here the authors identify the mRNA targets of P-bodies during DNA replication stress, and show that P-body proteins act to prevent toxic accumulation of these target transcripts.
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Affiliation(s)
- Raphael Loll-Krippleber
- Department of Biochemistry and Donnelly Centre, University of Toronto, 160 College Street, Toronto, ON, Canada, M5S 3E1
| | - Grant W Brown
- Department of Biochemistry and Donnelly Centre, University of Toronto, 160 College Street, Toronto, ON, Canada, M5S 3E1.
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22
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Ben Younes K, Body S, Costé É, Viailly PJ, Miloudi H, Coudre C, Jardin F, Ben Aissa-Fennira F, Sola B. A lowered 26S proteasome activity correlates with mantle lymphoma cell lines resistance to genotoxic stress. BMC Cancer 2017; 17:538. [PMID: 28797244 PMCID: PMC5553741 DOI: 10.1186/s12885-017-3530-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 08/03/2017] [Indexed: 01/04/2023] Open
Abstract
Background Mantle cell lymphoma (MCL) is a B-cell hemopathy characterized by the t(11;14) translocation and the aberrant overexpression of cyclin D1. This results in an unrestrained cell proliferation. Other genetic alterations are common in MCL cells such as SOX11 expression, mutations of ATM and/or TP53 genes, activation of the NF-κB signaling pathway and NOTCH receptors. These alterations lead to the deregulation of the apoptotic machinery and resistance to drugs. We observed that among a panel of MCL cell lines, REC1 cells were resistant towards genotoxic stress. We studied the molecular basis of this resistance. Methods We analyzed the cell response regarding apoptosis, senescence, cell cycle arrest, DNA damage response and finally the 26S proteasome activity following a genotoxic treatment that causes double strand DNA breaks. Results MCL cell lines displayed various sensitivity/resistance towards genotoxic stress and, in particular, REC1 cells did not enter apoptosis or senescence after an etoposide treatment. Moreover, the G2/M cell cycle checkpoint was deficient in REC1 cells. We observed that three main actors of apoptosis, senescence and cell cycle regulation (cyclin D1, MCL1 and CDC25A) failed to be degraded by the proteasome machinery in REC1 cells. We ruled out a default of the βTrCP E3-ubiquitine ligase but detected a lowered 26S proteasome activity in REC1 cells compared to other cell lines. Conclusion The resistance of MCL cells to genotoxic stress correlates with a low 26S proteasome activity. This could represent a relevant biomarker for a subtype of MCL patients with a poor response to therapies and a high risk of relapse. Electronic supplementary material The online version of this article (doi:10.1186/s12885-017-3530-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Khaoula Ben Younes
- Normandie Univ, INSERM UMR 1245, UNIROUEN, UNICAEN, Caen, France.,Faculté de médecine, Laboratoire de Génétique, d'Immunologie et de Pathologie humaines, Université de Tunis El Manar, Tunis, Tunisia
| | - Simon Body
- Normandie Univ, INSERM UMR 1245, UNIROUEN, UNICAEN, Caen, France
| | - Élodie Costé
- Normandie Univ, INSERM UMR 1245, UNIROUEN, UNICAEN, Caen, France
| | - Pierre-Julien Viailly
- Normandie Univ, INSERM UMR 1245, UNIROUEN, UNICAEN, Caen, France.,Département d'Hématologie Clinique, Centre de Lutte contre le Cancer Henri Becquerel, Rouen, France
| | - Hadjer Miloudi
- Normandie Univ, INSERM UMR 1245, UNIROUEN, UNICAEN, Caen, France
| | - Clémence Coudre
- Normandie Univ, INSERM UMR 1245, UNIROUEN, UNICAEN, Caen, France
| | - Fabrice Jardin
- Normandie Univ, INSERM UMR 1245, UNIROUEN, UNICAEN, Caen, France.,Département d'Hématologie Clinique, Centre de Lutte contre le Cancer Henri Becquerel, Rouen, France
| | - Fatma Ben Aissa-Fennira
- Faculté de médecine, Laboratoire de Génétique, d'Immunologie et de Pathologie humaines, Université de Tunis El Manar, Tunis, Tunisia
| | - Brigitte Sola
- Normandie Univ, INSERM UMR 1245, UNIROUEN, UNICAEN, Caen, France. .,MICAH, UFR Santé, CHU Côte de Nacre, 14032, Caen Cedex, France.
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23
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Chronically stressed or stress-preconditioned neurons fail to maintain stress granule assembly. Cell Death Dis 2017; 8:e2788. [PMID: 28492545 PMCID: PMC5520719 DOI: 10.1038/cddis.2017.199] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 03/31/2017] [Accepted: 05/04/2017] [Indexed: 12/18/2022]
Abstract
Dysregulation of stress granules (SGs) and their resident proteins contributes to pathogenesis of a number of (neuro)degenerative diseases. Phosphorylation of eIF2α is an event integrating different types of cellular stress and it is required for SG assembly. Phosphorylated eIF2α (p-eIF2α) is upregulated in the nervous system in some neurodegenerative conditions. We found that increasing p-eIF2α level by proteasomal inhibition in cultured cells, including mouse and human neurons, before a SG-inducing stress ('stress preconditioning'), limits their ability to maintain SG assembly. This is due to upregulation of PP1 phosphatase regulatory subunits GADD34 and/or CReP in preconditioned cells and early decline of p-eIF2α levels during subsequent acute stress. In two model systems with constitutively upregulated p-eIF2α, mouse embryonic fibroblasts lacking CReP and brain neurons of tau transgenic mice, SG formation was also impaired. Thus, neurons enduring chronic stress or primed by a transient mild stress fail to maintain p-eIF2α levels following subsequent acute stress, which would compromise protective function of SGs. Our findings provide experimental evidence on possible loss of function for SGs in certain neurodegenerative diseases.
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24
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ZNF395 Is an Activator of a Subset of IFN-Stimulated Genes. Mediators Inflamm 2017; 2017:1248201. [PMID: 28316371 PMCID: PMC5339479 DOI: 10.1155/2017/1248201] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 01/05/2017] [Indexed: 11/17/2022] Open
Abstract
Activation of the interferon (IFN) pathway in response to infection with pathogens results in the induction of IFN-stimulated genes (ISGs) including proinflammatory cytokines, which mount the proper antiviral immune response. However, aberrant expression of these genes is pathogenic to the host. In addition to IFN-induced transcription factors non-IFN-regulated factors contribute to the transcriptional control of ISGs. Here, we show by genome wide expression analysis, siRNA-mediated suppression and Doxycycline-induced overexpression that the cellular transcription factor ZNF395 activates a subset of ISGs including the chemokines CXCL10 and CXCL11 in keratinocytes. We found that ZNF395 acts independently of IFN but enhances the IFN-induced expression of CXCL10 and CXCL11. Luciferase reporter assays revealed a requirement of intact NFκB-binding sites for ZNF395 to stimulate the CXCL10 promoter. The transcriptional activation of CXCL10 and CXCL11 by ZNF395 was abolished after inhibition of IKK by BMS-345541, which increased the stability of ZNF395. ZNF395 encodes at least two motifs that mediate the enhanced degradation of ZNF395 in response to IKK activation. Thus, IKK is required for ZNF395-mediated activation of transcription and enhances its turn-over to keep the activity of ZNF395 low. Our results support a previously unrecognized role of ZNF395 in the innate immune response and inflammation.
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25
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Herzner AM, Wolter S, Zillinger T, Schmitz S, Barchet W, Hartmann G, Bartok E, Schlee M. G-rich DNA-induced stress response blocks type-I-IFN but not CXCL10 secretion in monocytes. Sci Rep 2016; 6:38405. [PMID: 27941826 PMCID: PMC5150577 DOI: 10.1038/srep38405] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Accepted: 11/03/2016] [Indexed: 12/17/2022] Open
Abstract
Excessive inflammation can cause damage to host cells and tissues. Thus, the secretion of inflammatory cytokines is tightly regulated at transcriptional, post-transcriptional and post-translational levels and influenced by cellular stress responses, such as endoplasmic reticulum (ER) stress or apoptosis. Here, we describe a novel type of post-transcriptional regulation of the type-I-IFN response that was induced in monocytes by cytosolic transfection of a short immunomodulatory DNA (imDNA), a G-tetrad forming CpG-free derivative of the TLR9 agonist ODN2216. When co-transfected with cytosolic nucleic acid stimuli (DNA or 3P-dsRNA), imDNA induced caspase-3 activation, translational shutdown and upregulation of stress-induced genes. This stress response inhibited the type-I-IFN induction at the translational level. By contrast, the induction of most type-I-IFN-associated chemokines, including Chemokine (C-X-C Motif) Ligand (CXCL)10 was not affected, suggesting a differential translational regulation of chemokines and type-I-IFN. Pan-caspase inhibitors could restore IFN-β secretion, yet, strikingly, caspase inhibition did not restore global translation but instead induced a compensatory increase in the transcription of IFN-β but not CXCL10. Altogether, our data provide evidence for a differential regulation of cytokine release at both transcriptional and post-transcriptional levels which suppresses type-I-IFN induction yet allows for CXCL10 secretion during imDNA-induced cellular stress.
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Affiliation(s)
- Anna-Maria Herzner
- Institute of Clinical Chemistry and Clinical Pharmacology, University Hospital Bonn, Bonn, Germany
| | - Steven Wolter
- Institute of Clinical Chemistry and Clinical Pharmacology, University Hospital Bonn, Bonn, Germany
| | - Thomas Zillinger
- Institute of Clinical Chemistry and Clinical Pharmacology, University Hospital Bonn, Bonn, Germany.,German Center for Infection Research (DZIF), Cologne-Bonn, Germany
| | - Saskia Schmitz
- Institute of Clinical Chemistry and Clinical Pharmacology, University Hospital Bonn, Bonn, Germany
| | - Winfried Barchet
- Institute of Clinical Chemistry and Clinical Pharmacology, University Hospital Bonn, Bonn, Germany.,German Center for Infection Research (DZIF), Cologne-Bonn, Germany
| | - Gunther Hartmann
- Institute of Clinical Chemistry and Clinical Pharmacology, University Hospital Bonn, Bonn, Germany
| | - Eva Bartok
- Institute of Clinical Chemistry and Clinical Pharmacology, University Hospital Bonn, Bonn, Germany
| | - Martin Schlee
- Institute of Clinical Chemistry and Clinical Pharmacology, University Hospital Bonn, Bonn, Germany
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26
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Pakos-Zebrucka K, Koryga I, Mnich K, Ljujic M, Samali A, Gorman AM. The integrated stress response. EMBO Rep 2016; 17:1374-1395. [PMID: 27629041 DOI: 10.15252/embr.201642195] [Citation(s) in RCA: 1482] [Impact Index Per Article: 185.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 08/23/2016] [Indexed: 02/06/2023] Open
Abstract
In response to diverse stress stimuli, eukaryotic cells activate a common adaptive pathway, termed the integrated stress response (ISR), to restore cellular homeostasis. The core event in this pathway is the phosphorylation of eukaryotic translation initiation factor 2 alpha (eIF2α) by one of four members of the eIF2α kinase family, which leads to a decrease in global protein synthesis and the induction of selected genes, including the transcription factor ATF4, that together promote cellular recovery. The gene expression program activated by the ISR optimizes the cellular response to stress and is dependent on the cellular context, as well as on the nature and intensity of the stress stimuli. Although the ISR is primarily a pro-survival, homeostatic program, exposure to severe stress can drive signaling toward cell death. Here, we review current understanding of the ISR signaling and how it regulates cell fate under diverse types of stress.
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Affiliation(s)
- Karolina Pakos-Zebrucka
- Apoptosis Research Centre, National University of Ireland Galway, Galway, Ireland School of Natural Sciences, National University of Ireland Galway, Galway, Ireland
| | - Izabela Koryga
- Apoptosis Research Centre, National University of Ireland Galway, Galway, Ireland School of Natural Sciences, National University of Ireland Galway, Galway, Ireland
| | - Katarzyna Mnich
- Apoptosis Research Centre, National University of Ireland Galway, Galway, Ireland School of Natural Sciences, National University of Ireland Galway, Galway, Ireland
| | - Mila Ljujic
- Apoptosis Research Centre, National University of Ireland Galway, Galway, Ireland School of Natural Sciences, National University of Ireland Galway, Galway, Ireland
| | - Afshin Samali
- Apoptosis Research Centre, National University of Ireland Galway, Galway, Ireland School of Natural Sciences, National University of Ireland Galway, Galway, Ireland
| | - Adrienne M Gorman
- Apoptosis Research Centre, National University of Ireland Galway, Galway, Ireland School of Natural Sciences, National University of Ireland Galway, Galway, Ireland
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Isolation of ubiquitinated substrates by tandem affinity purification of E3 ligase-polyubiquitin-binding domain fusions (ligase traps). Nat Protoc 2016; 11:291-301. [PMID: 26766115 DOI: 10.1038/nprot.2016.008] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Ubiquitination is an essential protein modification that influences eukaryotic processes ranging from substrate degradation to nonproteolytic pathway alterations, including DNA repair and endocytosis. Previous attempts to analyze substrates via physical association with their respective ubiquitin ligases have had some success. However, because of the transient nature of enzyme-substrate interactions and rapid protein degradation, detection of substrates remains a challenge. Ligase trapping is an affinity purification approach in which ubiquitin ligases are fused to a polyubiquitin-binding domain, which allows the isolation of ubiquitinated substrates. Immunoprecipitation is first used to enrich for proteins that are bound to the ligase trap. Subsequently, affinity purification is used under denaturing conditions to capture proteins conjugated with hexahistidine-tagged ubiquitin. By using this protocol, ubiquitinated substrates that are specific for a given ligase can be isolated for mass spectrometry or western blot analysis. After cells have been collected, the described protocol can be completed in 2-3 d.
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28
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Heo J, Eki R, Abbas T. Deregulation of F-box proteins and its consequence on cancer development, progression and metastasis. Semin Cancer Biol 2015; 36:33-51. [PMID: 26432751 DOI: 10.1016/j.semcancer.2015.09.015] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 09/25/2015] [Accepted: 09/25/2015] [Indexed: 01/28/2023]
Abstract
F-box proteins are substrate receptors of the SCF (SKP1-Cullin 1-F-box protein) E3 ubiquitin ligase that play important roles in a number of physiological processes and activities. Through their ability to assemble distinct E3 ubiquitin ligases and target key regulators of cellular activities for ubiquitylation and degradation, this versatile group of proteins is able to regulate the abundance of cellular proteins whose deregulated expression or activity contributes to disease. In this review, we describe the important roles of select F-box proteins in regulating cellular activities, the perturbation of which contributes to the initiation and progression of a number of human malignancies.
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Affiliation(s)
- Jinho Heo
- Department of Radiation Oncology, University of Virginia, Charlottesville, VA, USA
| | - Rebeka Eki
- Department of Radiation Oncology, University of Virginia, Charlottesville, VA, USA; Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA, USA
| | - Tarek Abbas
- Department of Radiation Oncology, University of Virginia, Charlottesville, VA, USA; Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA, USA; Center for Cell Signaling, University of Virginia, Charlottesville, VA, USA.
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