1
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Wang Y, Lan Q, Cheng X, Gao Y, Chang L, Xu P, Li Y. Quantitative Proteomics-Based Substrate Screening Revealed Cyclophilin Stabilization Regulated by Deubiquitinase Ubp7. J Proteome Res 2023; 22:2281-2292. [PMID: 37341107 DOI: 10.1021/acs.jproteome.2c00853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/22/2023]
Abstract
Quantitative proteomics has emerged as a crucial approach to identifying ubiquitinated substrates to investigate the functions of ubiquitination in cells. In this regard, although the substrate screening of certain enzymes in the ubiquitin system has been based on proteome or ubiquitinome level measurements, the direct comparison of these two approaches has not been determined to date. To quantitatively compare the efficiency and effectiveness of substrate screening from the entire proteomics to the ubiquitinomics filter, we used yeast deubiquitinating enzyme, Ubp7, as an example to evaluate it in this study. A total of 112 potential ubiquitinated substrates were identified from the ubiquitinomics level, whereas only 27 regulated substrates were identified from the entire proteomic screening, demonstrating the increased efficiency of ubiquitinomics quantitative analysis. Subsequently, we selected cyclophilin A (Cpr1) protein as an example, which was filtered out at the proteomics level but was a promising candidate according to the ubiquitinomics filter. Additional investigations revealed that Cpr1 possessed a K48-linked ubiquitin chain regulated by Ubp7, which may affect its homeostasis and, consequently, sensitivity to the therapeutic drug cyclosporine (CsA).
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Affiliation(s)
- Yonghong Wang
- Department of Biomedicine, School of Medicine, Guizhou University, Guiyang 550025, China
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences Beijing, Research Unit of Proteomics & Research and Development of New Drug of Chinese Academy of Medical Sciences, Institute of Lifeomics, 38 Science Park Road, Changping District, Beijing 102206, China
| | - Qiuyan Lan
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences Beijing, Research Unit of Proteomics & Research and Development of New Drug of Chinese Academy of Medical Sciences, Institute of Lifeomics, 38 Science Park Road, Changping District, Beijing 102206, China
| | - Xinyu Cheng
- School of Basic Medicine, Anhui Medical University, Hefei 230032, China
| | - Yuan Gao
- Central Laboratory of College of Horticulture, Nanjing Agricultural University, Nanjing 210095, People's Republic of China
| | - Lei Chang
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences Beijing, Research Unit of Proteomics & Research and Development of New Drug of Chinese Academy of Medical Sciences, Institute of Lifeomics, 38 Science Park Road, Changping District, Beijing 102206, China
| | - Ping Xu
- Department of Biomedicine, School of Medicine, Guizhou University, Guiyang 550025, China
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences Beijing, Research Unit of Proteomics & Research and Development of New Drug of Chinese Academy of Medical Sciences, Institute of Lifeomics, 38 Science Park Road, Changping District, Beijing 102206, China
- School of Basic Medicine, Anhui Medical University, Hefei 230032, China
- Key Laboratory of Microbial Diversity Research and Application of Hebei Province, School of Life Sciences, Hebei University, Baoding 071002, China
| | - Yanchang Li
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences Beijing, Research Unit of Proteomics & Research and Development of New Drug of Chinese Academy of Medical Sciences, Institute of Lifeomics, 38 Science Park Road, Changping District, Beijing 102206, China
- School of Basic Medicine, Anhui Medical University, Hefei 230032, China
- Key Laboratory of Microbial Diversity Research and Application of Hebei Province, School of Life Sciences, Hebei University, Baoding 071002, China
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2
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Site-specific proteomic strategies to identify ubiquitin and SUMO modifications: Challenges and opportunities. Semin Cell Dev Biol 2022; 132:97-108. [PMID: 34802913 DOI: 10.1016/j.semcdb.2021.11.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 11/08/2021] [Accepted: 11/08/2021] [Indexed: 12/14/2022]
Abstract
Ubiquitin and SUMO modify thousands of substrates to regulate most cellular processes. System-wide identification of ubiquitin and SUMO substrates provides global understanding of their cellular functions. In this review, we discuss the biological importance of site-specific modifications by ubiquitin and SUMO regulating the DNA damage response, protein quality control and cell cycle progression. Furthermore we discuss the machinery responsible for these modifications and methods to purify and identify ubiquitin and SUMO modified sites by mass spectrometry. We provide a framework to aid in the selection of appropriate purification, digestion and acquisition strategies suited to answer different biological questions. We highlight opportunities in the field for employing innovative technologies, as well as discuss challenges and long-standing questions in the field that are difficult to address with the currently available tools, emphasizing the need for further innovation.
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3
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Chen C, Wen M, Jin Y. 1DE-MS Profiling for Proteoform-Correlated Proteomic Analysis, by Combining SDS-PAGE, Whole-Gel Slicing, Quantitative LC-MS/MS, and Reconstruction of Gel Distributions of Several Thousands of Proteins. J Proteome Res 2022; 21:2311-2330. [PMID: 36018058 DOI: 10.1021/acs.jproteome.2c00180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
SDS-PAGE has often been used in proteomic analysis, but generally for sample prefractionation although the technique separates proteins by molecular masses (Mws) and the information would contribute to proteoform-level analysis. Here, we report a method that combines SDS-PAGE, whole-gel slicing, and quantitative LC-MS/MS for establishing gel distributions of several thousand proteins in a proteome. A previously obtained data set on rat cerebral cortex with cerebral ischemia-reperfusion injury1 was analyzed, and the gel distributions of 5906 proteins were reconstructed. These distributions, referred to as 1DE-MS profiles, revealed that about 30% of the proteins had more than one proteoform detected in the gels. The profiles were categorized into six types by distribution (narrow, dispersed, or broad) and relative deviations between the abundance-peak apparent Mws and calculated Mws. Only 56% of the proteins showed narrow distributions and matched Mws, while the others had rather complex profiles. Bioinformatic analysis on example profiles showed the resolved proteoforms involved alternative splicing, proteolytic processing, glycosylation and ubiquitination, fragmentation, and probably transmembrane structures. Profile-based differential analysis revealed that many of the disease-caused changes were proteoform dependent. This work provided a proteome-scale view of protein distributions in SDS-PAGE gels, and the method would be useful to obtain proteoform-correlated information for in-depth proteomics.
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Affiliation(s)
- Changming Chen
- Institute of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou 510006, P. R. China
| | - Meiling Wen
- Institute of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou 510006, P. R. China
| | - Ya Jin
- Institute of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou 510006, P. R. China
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4
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Yu K, Wang Z, Wu Z, Tan H, Mishra A, Peng J. High-Throughput Profiling of Proteome and Posttranslational Modifications by 16-Plex TMT Labeling and Mass Spectrometry. Methods Mol Biol 2021; 2228:205-224. [PMID: 33950493 PMCID: PMC8458009 DOI: 10.1007/978-1-0716-1024-4_15] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Mass spectrometry (MS)-based proteomic profiling of whole proteome and protein posttranslational modifications (PTMs) is a powerful technology to measure the dynamics of proteome with high throughput and deep coverage. The reproducibility of quantification benefits not only from the fascinating developments in high-performance liquid chromatography (LC) and high-resolution MS with enhanced scan rates but also from the invention of multiplexed isotopic labeling strategies, such as the tandem mass tags (TMT). In this chapter, we introduce a 16-plex TMT-LC/LC-MS/MS protocol for proteomic profiling of biological and clinical samples. The protocol includes protein extraction, enzymatic digestion, PTM peptide enrichment, TMT labeling, and two-dimensional reverse-phase liquid chromatography fractionation coupled with tandem mass spectrometry (MS/MS) analysis, followed by computational data processing. In general, more than 10,000 proteins and tens of thousands of PTM sites (e.g., phosphorylation and ubiquitination) can be confidently quantified. This protocol provides a general protein measurement tool, enabling the dissection of protein dysregulation in any biological samples and human diseases.
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Affiliation(s)
- Kaiwen Yu
- Departments of Structural Biology and Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Zhen Wang
- Departments of Structural Biology and Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Zhiping Wu
- Departments of Structural Biology and Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Haiyan Tan
- Center for Proteomics and Metabolomics, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Ashutosh Mishra
- Center for Proteomics and Metabolomics, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Junmin Peng
- Departments of Structural Biology and Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN, USA.
- Center for Proteomics and Metabolomics, St. Jude Children's Research Hospital, Memphis, TN, USA.
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5
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Proteomic approaches for the profiling of ubiquitylation events and their applications in drug discovery. J Proteomics 2020; 231:103996. [PMID: 33017648 DOI: 10.1016/j.jprot.2020.103996] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 08/27/2020] [Accepted: 09/27/2020] [Indexed: 01/23/2023]
Abstract
Protein ubiquitylation regulates almost all aspects of the biological processes including gene expression, DNA repair, cell proliferation and apoptosis in eukaryotic cells. Dysregulation of protein ubiquitylation caused by abnormal expression of enzymes in the ubiquitin system results in the onset of many diseases including cancer, neurodegenerative diseases, and metabolic syndromes. Therefore, targeting the ubiquitin system becomes a promising research area in drug discovery. Identification of protein ubiquitylation sites is critical for revealing the key ubiquitylation events associated with diseases and specific signaling pathways and for elucidating the biological functions of the specific ubiquitylation events. Many approaches that enrich for the ubiquitylated proteins and ubiquitylated peptides at the protein and peptide levels have been developed to facilitate their identification by MS. In this paper, we will review the proteomic approaches available for the identification of ubiquitylation events at the proteome scale and discuss their advantages and limitations. We will also brief the application of the profiling of ubiquitylation events in drug target discovery and in target validation for proteolysis-targeting chimera (PROTAC). Possible future research directions in this field will also be discussed. SIGNIFICANCE: Ubiquitylation plays critical roles in regulating many biological processes in eukaryotic cells. Identification of ubiquitylation sites can provide the essential information for the functional study of the specific modified substrates. Since ubiquitylated proteins have much lower abundance than non-ubiquitylated proteins, enrichment of ubiquitylated proteins or peptides is critical for their identification by MS. This review focuses on different enrichment approaches that facilitate their isolation and identification by MS and discusses the advantages and drawbacks of these approaches. The application of the profiling of ubiquitylation events in drug target discovery and future research directions will be beneficial to the research community.
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6
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Lan Q, Wang Y, Sun Z, Li Y, Zhang C, Chang L, Gao Y, Wu J, Wang F, Xu P. Quantitative Proteomics Combined with Two Genetic Strategies for Screening Substrates of Ubiquitin Ligase Hrt3. J Proteome Res 2020; 19:493-502. [PMID: 31789040 DOI: 10.1021/acs.jproteome.9b00673] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ubiquitin ligases (E3s) serve as key regulators for the ubiquitylation-mediated pathway. The identification of the corresponding relationship between E3 and its substrates is challenging but required for understanding the regulatory network of ubiquitylation. The low abundance of ubiquitinated conjugates and high redundancy of E3 substrate regulation made the screening pretty hard. Herein, we combined SILAC-based quantitative proteomics with two contrary genetic methods (overexpression and knockout) in theory for E3 (Hrt3, the F-box subunit of the SCF complex) substrate screening. The knockout method could not overcome the constraint mentioned above, while the overexpression approach turned on the access to the potential substrates of E3. Subsequently, we obtained 77 candidates, which are involved in many critical biological processes and need to be verified in the future. Within these candidates, we confirmed the relationship between one of the candidates Nce103 and Hrt3 and linked Hrt3 with oxygen sensitivity and oxidative stress response in which Nce103 took part as well. This research is also beneficial for understanding the impact of oxygen supply on regulation of yeast growth through the ubiquitination of Nce103.
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Affiliation(s)
- Qiuyan Lan
- School of Basic Medical Science, Key Laboratory of Combinatorial Biosynthesis and Drug Discovery of Ministry of Education, School of Pharmaceutical Sciences , Wuhan University , Wuhan 430071 , P. R. China.,State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing) , Beijing Institute of Lifeomics , Beijing 102206 , P. R. China
| | - Yihao Wang
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing) , Beijing Institute of Lifeomics , Beijing 102206 , P. R. China.,Department of Pharmacology and Toxicology , Beijing Institute of Radiation Medicine , Beijing 100850 , P. R. China
| | - Zhen Sun
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing) , Beijing Institute of Lifeomics , Beijing 102206 , P. R. China
| | - Yanchang Li
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing) , Beijing Institute of Lifeomics , Beijing 102206 , P. R. China
| | - Cheng Zhang
- School of Basic Medical Science, Key Laboratory of Combinatorial Biosynthesis and Drug Discovery of Ministry of Education, School of Pharmaceutical Sciences , Wuhan University , Wuhan 430071 , P. R. China
| | - Lei Chang
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing) , Beijing Institute of Lifeomics , Beijing 102206 , P. R. China
| | - Yue Gao
- Department of Pharmacology and Toxicology , Beijing Institute of Radiation Medicine , Beijing 100850 , P. R. China
| | - Junzhu Wu
- School of Basic Medical Science, Key Laboratory of Combinatorial Biosynthesis and Drug Discovery of Ministry of Education, School of Pharmaceutical Sciences , Wuhan University , Wuhan 430071 , P. R. China
| | - Fuqiang Wang
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing) , Beijing Institute of Lifeomics , Beijing 102206 , P. R. China
| | - Ping Xu
- School of Basic Medical Science, Key Laboratory of Combinatorial Biosynthesis and Drug Discovery of Ministry of Education, School of Pharmaceutical Sciences , Wuhan University , Wuhan 430071 , P. R. China.,State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing) , Beijing Institute of Lifeomics , Beijing 102206 , P. R. China.,Second Clinical Medicine College , Guangzhou University Chinese Medicine , Guangzhou 510120 , P. R. China.,Research Unit of Proteomics & Research and Development of New Drug , Chinese Academy of Medical Sciences , Beijing 100730 , P. R. China
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7
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Luessen DJ, Sun H, McGinnis MM, Hagstrom M, Marrs G, McCool BA, Chen R. Acute ethanol exposure reduces serotonin receptor 1A internalization by increasing ubiquitination and degradation of β-arrestin2. J Biol Chem 2019; 294:14068-14080. [PMID: 31366729 DOI: 10.1074/jbc.ra118.006583] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2018] [Revised: 07/23/2019] [Indexed: 11/06/2022] Open
Abstract
Acute alcohol exposure alters the trafficking and function of many G-protein-coupled receptors (GPCRs) that are associated with aberrant behavioral responses to alcohol. However, the molecular mechanisms underlying alcohol-induced changes in GPCR function remain unclear. β-Arrestin is a key player involved in the regulation of GPCR internalization and thus controls the magnitude and duration of GPCR signaling. Although β-arrestin levels are influenced by various drugs of abuse, the effect of alcohol exposure on β-arrestin expression and β-arrestin-mediated GPCR trafficking is poorly understood. Here, we found that acute ethanol exposure increases β-arrestin2 degradation via its increased ubiquitination in neuroblastoma-2a (N2A) cells and rat prefrontal cortex (PFC). β-Arrestin2 ubiquitination was likely mediated by the E3 ligase MDM2 homolog (MDM2), indicated by an increased coupling between β-arrestin2 and MDM2 in response to acute ethanol exposure in both N2A cells and rat PFC homogenates. Importantly, ethanol-induced β-arrestin2 reduction was reversed by siRNA-mediated MDM2 knockdown or proteasome inhibition in N2A cells, suggesting β-arrestin2 degradation is mediated by MDM2 through the proteasomal pathway. Using serotonin 5-HT1A receptors (5-HT1ARs) as a model receptor system, we found that ethanol dose-dependently inhibits 5-HT1AR internalization and that MDM2 knockdown reverses this effect. Moreover, ethanol both reduced β-arrestin2 levels and delayed agonist-induced β-arrestin2 recruitment to the membrane. We conclude that β-arrestin2 dysregulation by ethanol impairs 5-HT1AR trafficking. Our findings reveal a critical molecular mechanism underlying ethanol-induced alterations in GPCR internalization and implicate β-arrestin as a potential player mediating behavioral responses to acute alcohol exposure.
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Affiliation(s)
- Deborah J Luessen
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston Salem, North Carolina 27157
| | - Haiguo Sun
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston Salem, North Carolina 27157
| | - Molly M McGinnis
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston Salem, North Carolina 27157
| | - Michael Hagstrom
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston Salem, North Carolina 27157
| | - Glen Marrs
- Center for Molecular Signaling, Department of Biology, Wake Forest University, Winston Salem, North Carolina 27106
| | - Brian A McCool
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston Salem, North Carolina 27157
| | - Rong Chen
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston Salem, North Carolina 27157 .,Center for Molecular Signaling, Department of Biology, Wake Forest University, Winston Salem, North Carolina 27106.,Center for the Neurobiology of Addiction Treatment, Wake Forest School of Medicine, Winston Salem, North Carolina 27157
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8
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Matsumoto ML, Castellanos ER, Zeng YJ, Kirkpatrick DS. Interpreting the Language of Polyubiquitin with Linkage-Specific Antibodies and Mass Spectrometry. Methods Mol Biol 2019; 1844:385-400. [PMID: 30242722 DOI: 10.1007/978-1-4939-8706-1_24] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/26/2023]
Abstract
Posttranslational modification of cellular proteins by ubiquitin serves a variety of functions. Among the multitude of ubiquitin substrates, ubiquitin itself is the most prevalent. For many years, the direct detection of polyubiquitin chains attached to cellular substrates was not practical, with cell biologists relegated to indirect approaches involving site-directed mutagenesis or in vitro biochemistry. Recent advances in two technologies-polyubiquitin linkage-specific antibodies and mass spectrometry proteomics, have overcome that limitation. Using one or both of these, the direct analysis of polyubiquitin chain linkages on cellular substrate proteins may be performed. This paper describes the complimentary nature of linkage-specific antibodies and mass spectrometry proteomics for the characterization of complex ubiquitin signals using lessons learned in early development of both technologies.
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Affiliation(s)
- Marissa L Matsumoto
- Department of Structural Biology, Genentech, Inc., South San Francisco, CA, USA.
| | - Erick R Castellanos
- Department of Structural Biology, Genentech, Inc., South San Francisco, CA, USA
| | - Yi Jimmy Zeng
- Department of Microchemistry, Proteomics and Lipidomics, Genentech, Inc., South San Francisco, CA, USA
| | - Donald S Kirkpatrick
- Department of Microchemistry, Proteomics and Lipidomics, Genentech, Inc., South San Francisco, CA, USA.
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9
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Limoncelli KA, Merrikh CN, Moore MJ. ASC1 and RPS3: new actors in 18S nonfunctional rRNA decay. RNA (NEW YORK, N.Y.) 2017; 23:1946-1960. [PMID: 28956756 PMCID: PMC5689013 DOI: 10.1261/rna.061671.117] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Accepted: 09/23/2017] [Indexed: 06/07/2023]
Abstract
In budding yeast, inactivating mutations within the 40S ribosomal subunit decoding center lead to 18S rRNA clearance by a quality control mechanism known as nonfunctional 18S rRNA decay (18S NRD). We previously showed that 18S NRD is functionally related to No-Go mRNA Decay (NGD), a pathway for clearing translation complexes stalled on aberrant mRNAs. Whereas the NGD factors Dom34p and Hbs1p contribute to 18S NRD, their genetic deletion (either singly or in combination) only partially stabilizes mutant 18S rRNA. Here we identify Asc1p (aka RACK1) and Rps3p, both stable 40S subunit components, as additional 18S NRD factors. Complete stabilization of mutant 18S rRNA in dom34Δ;asc1Δ and hbs1Δ;asc1Δ strains indicates the existence of two genetically separable 18S NRD pathways. A small region of the Rps3p C-terminal tail known to be subject to post-translational modification is also crucial for 18S NRD. We combine these findings with the effects of mutations in the 5' → 3' and 3' → 5' decay machinery to propose a model wherein multiple targeting and decay pathways kinetically contribute to 18S NRD.
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Affiliation(s)
- Kelly A Limoncelli
- Department of Biochemistry and Molecular Pharmacology, RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Christopher N Merrikh
- Department of Biochemistry and Molecular Pharmacology, RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Melissa J Moore
- Department of Biochemistry and Molecular Pharmacology, RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
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10
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Detection of Ubiquitinated Peroxisomal Proteins in Yeast. Methods Mol Biol 2017. [PMID: 28409467 DOI: 10.1007/978-1-4939-6937-1_22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Ubiquitination is involved in different aspects of peroxisome formation, maintenance, and degradation. Consequently, simple methods for detecting ubiquitinated peroxisomal proteins are extremely useful in peroxisomal research. Here, we describe an immunoprecipitation-based technique that can be used to assess peroxisomal protein ubiquitination in yeast.
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11
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Casanovas A, Pinto-Llorente R, Carrascal M, Abian J. Large-Scale Filter-Aided Sample Preparation Method for the Analysis of the Ubiquitinome. Anal Chem 2017; 89:3840-3846. [DOI: 10.1021/acs.analchem.6b04804] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Albert Casanovas
- Proteomics
Laboratory CSIC/UAB, Institute of Biomedical Research of Barcelona, Spanish National Research Council (IIBB-CSIC/IDIBAPS), E-08036 Barcelona, Spain
| | - Roberto Pinto-Llorente
- Proteomics
Laboratory CSIC/UAB, Institute of Biomedical Research of Barcelona, Spanish National Research Council (IIBB-CSIC/IDIBAPS), E-08036 Barcelona, Spain
| | - Montserrat Carrascal
- Proteomics
Laboratory CSIC/UAB, Institute of Biomedical Research of Barcelona, Spanish National Research Council (IIBB-CSIC/IDIBAPS), E-08036 Barcelona, Spain
| | - Joaquin Abian
- Proteomics
Laboratory CSIC/UAB, Institute of Biomedical Research of Barcelona, Spanish National Research Council (IIBB-CSIC/IDIBAPS), E-08036 Barcelona, Spain
- Autonomous University of Barcelona, E-08193 Bellaterra, Spain
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12
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Gao Y, Li Y, Zhang C, Zhao M, Deng C, Lan Q, Liu Z, Su N, Wang J, Xu F, Xu Y, Ping L, Chang L, Gao H, Wu J, Xue Y, Deng Z, Peng J, Xu P. Enhanced Purification of Ubiquitinated Proteins by Engineered Tandem Hybrid Ubiquitin-binding Domains (ThUBDs). Mol Cell Proteomics 2016; 15:1381-96. [PMID: 27037361 DOI: 10.1074/mcp.o115.051839] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Indexed: 11/06/2022] Open
Abstract
Ubiquitination is one of the most common post-translational modifications, regulating protein stability and function. However, the proteome-wide profiling of ubiquitinated proteins remains challenging due to their low abundance in cells. In this study, we systematically evaluated the affinity of ubiquitin-binding domains (UBDs) to different types of ubiquitin chains. By selecting UBDs with high affinity and evaluating various UBD combinations with different lengths and types, we constructed two artificial tandem hybrid UBDs (ThUBDs), including four UBDs made of DSK2p-derived ubiquitin-associated (UBA) and ubiquilin 2-derived UBA (ThUDQ2) and of DSK2p-derived UBA and RABGEF1-derived A20-ZnF (ThUDA20). ThUBD binds to ubiquitinated proteins, with markedly higher affinity than naturally occurring UBDs. Furthermore, it displays almost unbiased high affinity to all seven lysine-linked chains. Using ThUBD-based profiling with mass spectrometry, we identified 1092 and 7487 putative ubiquitinated proteins from yeast and mammalian cells, respectively, of which 362 and 1125 proteins had ubiquitin-modified sites. These results demonstrate that ThUBD is a refined and promising approach for enriching the ubiquitinated proteome while circumventing the need to overexpress tagged ubiquitin variants and use antibodies to recognize ubiquitin remnants, thus providing a readily accessible tool for the protein ubiquitination research community.
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Affiliation(s)
- Yuan Gao
- From the ‡State Key Laboratory of Proteomics, National Engineering Research Center for Protein Drugs, Beijing Proteome Research Center, National Center for Protein Sciences Beijing, Beijing Institute of Radiation Medicine, Beijing 102206,China
| | - Yanchang Li
- From the ‡State Key Laboratory of Proteomics, National Engineering Research Center for Protein Drugs, Beijing Proteome Research Center, National Center for Protein Sciences Beijing, Beijing Institute of Radiation Medicine, Beijing 102206,China
| | - Chengpu Zhang
- From the ‡State Key Laboratory of Proteomics, National Engineering Research Center for Protein Drugs, Beijing Proteome Research Center, National Center for Protein Sciences Beijing, Beijing Institute of Radiation Medicine, Beijing 102206,China
| | - Mingzhi Zhao
- From the ‡State Key Laboratory of Proteomics, National Engineering Research Center for Protein Drugs, Beijing Proteome Research Center, National Center for Protein Sciences Beijing, Beijing Institute of Radiation Medicine, Beijing 102206,China
| | - Chen Deng
- From the ‡State Key Laboratory of Proteomics, National Engineering Research Center for Protein Drugs, Beijing Proteome Research Center, National Center for Protein Sciences Beijing, Beijing Institute of Radiation Medicine, Beijing 102206,China
| | - Qiuyan Lan
- the ¶School of Basic Medical Science, Key Laboratory of Combinatorial Biosynthesis and Drug Discovery of Ministry of Education, School of Pharmaceutical Sciences, Wuhan University, Wuhan 430071, China
| | - Zexian Liu
- the ‖Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China; and
| | - Na Su
- From the ‡State Key Laboratory of Proteomics, National Engineering Research Center for Protein Drugs, Beijing Proteome Research Center, National Center for Protein Sciences Beijing, Beijing Institute of Radiation Medicine, Beijing 102206,China
| | - Jingwei Wang
- the ¶School of Basic Medical Science, Key Laboratory of Combinatorial Biosynthesis and Drug Discovery of Ministry of Education, School of Pharmaceutical Sciences, Wuhan University, Wuhan 430071, China
| | - Feng Xu
- From the ‡State Key Laboratory of Proteomics, National Engineering Research Center for Protein Drugs, Beijing Proteome Research Center, National Center for Protein Sciences Beijing, Beijing Institute of Radiation Medicine, Beijing 102206,China
| | - Yongru Xu
- From the ‡State Key Laboratory of Proteomics, National Engineering Research Center for Protein Drugs, Beijing Proteome Research Center, National Center for Protein Sciences Beijing, Beijing Institute of Radiation Medicine, Beijing 102206,China
| | - Lingyan Ping
- the ¶School of Basic Medical Science, Key Laboratory of Combinatorial Biosynthesis and Drug Discovery of Ministry of Education, School of Pharmaceutical Sciences, Wuhan University, Wuhan 430071, China
| | - Lei Chang
- From the ‡State Key Laboratory of Proteomics, National Engineering Research Center for Protein Drugs, Beijing Proteome Research Center, National Center for Protein Sciences Beijing, Beijing Institute of Radiation Medicine, Beijing 102206,China
| | - Huiying Gao
- From the ‡State Key Laboratory of Proteomics, National Engineering Research Center for Protein Drugs, Beijing Proteome Research Center, National Center for Protein Sciences Beijing, Beijing Institute of Radiation Medicine, Beijing 102206,China
| | - Junzhu Wu
- the ¶School of Basic Medical Science, Key Laboratory of Combinatorial Biosynthesis and Drug Discovery of Ministry of Education, School of Pharmaceutical Sciences, Wuhan University, Wuhan 430071, China
| | - Yu Xue
- the ‖Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China; and
| | - Zixin Deng
- the ¶School of Basic Medical Science, Key Laboratory of Combinatorial Biosynthesis and Drug Discovery of Ministry of Education, School of Pharmaceutical Sciences, Wuhan University, Wuhan 430071, China
| | - Junmin Peng
- the **Departments of Structural Biology and Developmental Neurobiology, St. Jude Proteomics Facility, St. Jude Children's Research Hospital, Memphis, Tennessee 38105
| | - Ping Xu
- From the ‡State Key Laboratory of Proteomics, National Engineering Research Center for Protein Drugs, Beijing Proteome Research Center, National Center for Protein Sciences Beijing, Beijing Institute of Radiation Medicine, Beijing 102206,China; the ¶School of Basic Medical Science, Key Laboratory of Combinatorial Biosynthesis and Drug Discovery of Ministry of Education, School of Pharmaceutical Sciences, Wuhan University, Wuhan 430071, China;
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O'Leary CE, Lewis EL, Oliver PM. Ubiquitylation as a Rheostat for TCR Signaling: From Targeted Approaches Toward Global Profiling. Front Immunol 2015; 6:618. [PMID: 26732666 PMCID: PMC4679856 DOI: 10.3389/fimmu.2015.00618] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 11/26/2015] [Indexed: 12/24/2022] Open
Abstract
T cell receptor (TCR) signaling must be precisely tuned to limit collateral damage and prevent reactivity to self, while still allowing robust protective immune responses that control pathogen invasion. One process that can be used to promote, modify, or terminate TCR signaling is ubiquitylation. During ubiquitylation, ubiquitin is covalently attached to target proteins through a multistep process, in which E3 ubiquitin ligases promote the formation of ubiquitin chains on selected substrates. Ubiquitylation can facilitate protein–protein interactions, direct a protein to a specific subcellular location, or initiate protein destruction. Like phosphorylation, ubiquitylation is a reversible process – deubiquitylating enzymes counteract ligase function by removing ubiquitin chains. This reversibility also allows for ubiquitin chain “editing.” Based on an emerging wealth of information from genetic loss-of-function studies showing that deregulation of ubiquitylation pathways leads to immune dysfunction, it has become increasingly apparent that the dynamic process of ubiquitylation is critical for normal immune cell function. In this review, we will describe how ubiquitylation acts as a key modulator and integrator of signaling downstream of TCR engagement. Specifically, we highlight the known roles of the substrate-specific E3 ligases and deubiquitylating enzymes in TCR signaling and T cell activation. While it is clear that ubiquitin enzymes tune T cell signaling and T cell function, elucidating the molecular mechanisms by which these proteins modulate T cells has met with significant challenges. Identifying substrates of these enzymes has been a particular challenge, and thus substrates of many E3 ligases and deubiquitylating enzymes remain largely unknown. To that end, we discuss the promise, and some practical considerations, of using proteomics-based techniques for unbiased identification of putative substrates of ubiquitin cascade proteins within primary T cells. These methods provide an exciting opportunity for further defining how TCR signals are regulated and for identifying new targets for therapeutic modulation.
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Affiliation(s)
- Claire E O'Leary
- Perelman School of Medicine, University of Pennsylvania , Philadelphia, PA , USA
| | - Emma L Lewis
- Perelman School of Medicine, University of Pennsylvania , Philadelphia, PA , USA
| | - Paula M Oliver
- Perelman School of Medicine, University of Pennsylvania , Philadelphia, PA , USA
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14
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Beaudette P, Popp O, Dittmar G. Proteomic techniques to probe the ubiquitin landscape. Proteomics 2015; 16:273-87. [PMID: 26460060 DOI: 10.1002/pmic.201500290] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2015] [Revised: 09/03/2015] [Accepted: 10/06/2015] [Indexed: 01/06/2023]
Abstract
Protein ubiquitination is a powerful modulator of cellular functions. Classically linked to the degradation of proteins, it also plays a role in intracellular localization, DNA damage response, vesicle fusion events, and the immune and transcriptional responses. Ubiquitin is versatile and can code for several distinct signals, either by adding a single ubiquitin or forming a chain of ubiquitins on the target protein. The enzymatic cascade associated with the cellular process determines the nature of the modification. Numerous efforts have been made for the identification of ubiquitin acceptor sites in the target proteins using genetic, biochemical or MS-based proteomic methods, such as affinity-based enrichment of ubiquitinated proteins, and antibody-based enrichment of modified peptides. Modern instrumentation enables quantitative MS strategies to identify and characterize hundreds of ubiquitin substrates in a single analysis making it the dominant method for ubiquitin site detection. Characterization of the interubiquitin connectivity in ubiquitin polymers has also moved into focus, with the field of targeted proteomics techniques proving invaluable for identifying and quantifying linkage types found in such polyubiquitin chains. This review seeks to provide an overview of the many MS-based proteomics techniques available for exploring this dynamic field.
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Affiliation(s)
- Patrick Beaudette
- Department of Mass Spectrometry, Max-Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Oliver Popp
- Department of Mass Spectrometry, Max-Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Gunnar Dittmar
- Department of Mass Spectrometry, Max-Delbrück Center for Molecular Medicine, Berlin, Germany
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15
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Chicooree N, Unwin RD, Griffiths JR. The application of targeted mass spectrometry-based strategies to the detection and localization of post-translational modifications. MASS SPECTROMETRY REVIEWS 2015; 34:595-626. [PMID: 24737647 DOI: 10.1002/mas.21421] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2013] [Accepted: 12/10/2013] [Indexed: 06/03/2023]
Abstract
This review describes some of the more interesting and imaginative ways in which mass spectrometry has been utilized to study a number of important post-translational modifications over the past two decades; from circa 1990 to 2013. A diverse range of modifications is covered, including citrullination, sulfation, hydroxylation and sumoylation. A summary of the biological role of each modification described, along with some brief mechanistic detail, is also included. Emphasis has been placed on strategies specifically aimed at detecting target modifications, as opposed to more serendipitous modification discovery approaches, which rely upon straightforward product ion scanning methods. The authors have intentionally excluded from this review both phosphorylation and glycosylation since these major modifications have been extensively reviewed elsewhere.
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Affiliation(s)
- Navin Chicooree
- CRUK Manchester Institute, University of Manchester, Wilmslow Road, Manchester, M20 4BX, UK
- School of Chemistry, University of Manchester, Brunswick Street, Manchester, M13 9SU, UK
| | - Richard D Unwin
- Centre for Advanced Discovery and Experimental Therapeutics (CADET), Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Sciences Centre, Manchester, M13 9WL, UK
- Institute of Human Development, Faculty of Medical and Human Sciences, University of Manchester, Manchester, UK
| | - John R Griffiths
- CRUK Manchester Institute, University of Manchester, Wilmslow Road, Manchester, M20 4BX, UK
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16
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Thomas SN, Zhang H, Cotter RJ. Application of quantitative proteomics to the integrated analysis of the ubiquitylated and global proteomes of xenograft tumor tissues. Clin Proteomics 2015; 12:14. [PMID: 26019700 PMCID: PMC4445283 DOI: 10.1186/s12014-015-9086-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 05/11/2015] [Indexed: 01/12/2023] Open
Abstract
Background Post-translational modification by ubiquitin is a fundamental regulatory mechanism that is implicated in many cellular processes including the cell cycle, apoptosis, cell adhesion, angiogenesis, and tumor growth. The low stoichiometry of ubiquitylation presents an analytical challenge for the detection of endogenously modified proteins in the absence of enrichment strategies. The recent availability of antibodies recognizing peptides with Lys residues containing a di-Gly ubiquitin remnant (K-ε-GG) has greatly improved the ability to enrich and identify ubiquitylation sites from complex protein lysates via mass spectrometry. To date, there have not been any published studies that quantitatively assess the changes in endogenous ubiquitin-modification protein stoichiometry status at the proteome level from different tissues. Results In this study, we applied an integrated quantitative mass spectrometry based approach using isobaric tags for relative and absolute quantitation (iTRAQ) to interrogate the ubiquitin-modified proteome and the cognate global proteome levels from luminal and basal breast cancer patient-derived xenograft tissues. Among the proteins with quantitative global and ubiquitylation data, 91 % had unchanged levels of total protein relative abundance, and less than 5 % of these proteins had up- or down-regulated ubiquitylation levels. Of particular note, greater than half of the proteins with observed changes in their total protein level also had up- or down-regulated changes in their ubiquitylation level. Conclusions This is the first report of the application of iTRAQ-based quantification to the integrated analysis of the ubiquitylated and global proteomes at the tissue level. Our results underscore the importance of conducting integrated analyses of the global and ubiquitylated proteomes toward elucidating the specific functional significance of ubiquitylation. Electronic supplementary material The online version of this article (doi:10.1186/s12014-015-9086-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Stefani N Thomas
- Department of Pathology, Clinical Chemistry Division, Johns Hopkins University School of Medicine, 1550 Orleans Street CRBII Room 3M06, Baltimore, MD 21231 USA
| | - Hui Zhang
- Department of Pathology, Clinical Chemistry Division, Johns Hopkins University School of Medicine, 1550 Orleans Street CRBII Room 3M06, Baltimore, MD 21231 USA
| | - Robert J Cotter
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
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17
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Böhm S, Mihalevic MJ, Casal MA, Bernstein KA. Disruption of SUMO-targeted ubiquitin ligases Slx5-Slx8/RNF4 alters RecQ-like helicase Sgs1/BLM localization in yeast and human cells. DNA Repair (Amst) 2014; 26:1-14. [PMID: 25588990 DOI: 10.1016/j.dnarep.2014.12.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 12/16/2014] [Accepted: 12/17/2014] [Indexed: 10/24/2022]
Abstract
RecQ-like helicases are a highly conserved protein family that functions during DNA repair and, when mutated in humans, is associated with cancer and/or premature aging syndromes. The budding yeast RecQ-like helicase Sgs1 has important functions in double-strand break (DSB) repair of exogenously induced breaks, as well as those that arise endogenously, for example during DNA replication. To further investigate Sgs1's regulation, we analyzed the subcellular localization of a fluorescent fusion of Sgs1 upon DNA damage. Consistent with a role in DSB repair, Sgs1 recruitment into nuclear foci in asynchronous cultures increases after ionizing radiation (IR) and after exposure to the alkylating agent methyl methanesulfonate (MMS). Yet, despite the importance of Sgs1 in replicative damage repair and in contrast to its elevated protein levels during S-phase, we find that the number of Sgs1 foci decreases upon nucleotide pool depletion by hydroxyurea (HU) treatment and that this negative regulation depends on the intra S-phase checkpoint kinase Mec1. Importantly, we identify the SUMO-targeted ubiquitin ligase (STUbL) complex Slx5-Slx8 as a negative regulator of Sgs1 foci, both spontaneously and upon replicative damage. Slx5-Slx8 regulation of Sgs1 foci is likely conserved in eukaryotes, since expression of the mammalian Slx5-Slx8 functional homologue, RNF4, restores Sgs1 focus number in slx8 cells and furthermore, knockdown of RNF4 leads to more BLM foci in U-2 OS cells. Our results point to a model where RecQ-like helicase subcellular localization is regulated by STUbLs in response to DNA damage, presumably to prevent illegitimate recombination events.
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Affiliation(s)
- Stefanie Böhm
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, University of Pittsburgh Cancer Institute, Pittsburgh, PA 15213, USA
| | - Michael Joseph Mihalevic
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, University of Pittsburgh Cancer Institute, Pittsburgh, PA 15213, USA
| | - Morgan Alexandra Casal
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, University of Pittsburgh Cancer Institute, Pittsburgh, PA 15213, USA
| | - Kara Anne Bernstein
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, University of Pittsburgh Cancer Institute, Pittsburgh, PA 15213, USA.
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Diner I, Hales CM, Bishof I, Rabenold L, Duong DM, Yi H, Laur O, Gearing M, Troncoso J, Thambisetty M, Lah JJ, Levey AI, Seyfried NT. Aggregation properties of the small nuclear ribonucleoprotein U1-70K in Alzheimer disease. J Biol Chem 2014; 289:35296-313. [PMID: 25355317 DOI: 10.1074/jbc.m114.562959] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Recent evidence indicates that U1-70K and other U1 small nuclear ribonucleoproteins are Sarkosyl-insoluble and associate with Tau neurofibrillary tangles selectively in Alzheimer disease (AD). Currently, the mechanisms underlying the conversion of soluble nuclear U1 small nuclear ribonucleoproteins into insoluble cytoplasmic aggregates remain elusive. Based on the biochemical and subcellular distribution properties of U1-70K in AD, we hypothesized that aggregated U1-70K itself or other biopolymers (e.g. proteins or nucleic acids) interact with and sequester natively folded soluble U1-70K into insoluble aggregates. Here, we demonstrate that total homogenates from AD brain induce soluble U1-70K from control brain or recombinant U1-70K to become Sarkosyl-insoluble. This effect was not dependent on RNA and did not correlate with detergent-insoluble Tau levels as AD homogenates with reduced levels of these components were still capable of inducing U1-70K aggregation. In contrast, proteinase K-treated AD homogenates and Sarkosyl-soluble AD fractions were unable to induce U1-70K aggregation, indicating that aggregated proteins in AD brain are responsible for inducing soluble U1-70K aggregation. It was determined that the C terminus of U1-70K, which harbors two disordered low complexity (LC) domains, is necessary for U1-70K aggregation. Moreover, both LC1 and LC2 domains were sufficient for aggregation. Finally, protein cross-linking and mass spectrometry studies demonstrated that a U1-70K fragment harboring the LC1 domain directly interacts with aggregated U1-70K in AD brain. Our results support a hypothesis that aberrant forms of U1-70K in AD can directly sequester soluble forms of U1-70K into insoluble aggregates.
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Affiliation(s)
- Ian Diner
- From the Departments of Biochemistry and the Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Chadwick M Hales
- the Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, Georgia 30322 Neurology
| | - Isaac Bishof
- From the Departments of Biochemistry and the Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Lake Rabenold
- From the Departments of Biochemistry and the Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Duc M Duong
- From the Departments of Biochemistry and the Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Hong Yi
- Emory University School of Medicine, Atlanta, Georgia 30322 Robert P. Apkarian Integrated Electron Microscopy Core
| | - Oskar Laur
- Emory University School of Medicine, Atlanta, Georgia 30322 Division of Microbiology, and Yerkes Research Center, Emory University, Atlanta, Georgia 30322
| | - Marla Gearing
- the Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, Georgia 30322 the Departments of Experimental Pathology and
| | - Juan Troncoso
- Pathology and Neurology, Johns Hopkins School of Medicine, Baltimore, Maryland 21205
| | | | - James J Lah
- the Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, Georgia 30322 Neurology
| | - Allan I Levey
- the Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, Georgia 30322 Neurology
| | - Nicholas T Seyfried
- From the Departments of Biochemistry and the Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, Georgia 30322 Neurology,
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19
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Efficient mRNA polyadenylation requires a ubiquitin-like domain, a zinc knuckle, and a RING finger domain, all contained in the Mpe1 protein. Mol Cell Biol 2014; 34:3955-67. [PMID: 25135474 DOI: 10.1128/mcb.00077-14] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Almost all eukaryotic mRNAs must be polyadenylated at their 3' ends to function in protein synthesis. This modification occurs via a large nuclear complex that recognizes signal sequences surrounding a poly(A) site on mRNA precursor, cleaves at that site, and adds a poly(A) tail. While the composition of this complex is known, the functions of some subunits remain unclear. One of these is a multidomain protein called Mpe1 in the yeast Saccharomyces cerevisiae and RBBP6 in metazoans. The three conserved domains of Mpe1 are a ubiquitin-like (UBL) domain, a zinc knuckle, and a RING finger domain characteristic of some ubiquitin ligases. We show that mRNA 3'-end processing requires all three domains of Mpe1 and that more than one region of Mpe1 is involved in contact with the cleavage/polyadenylation factor in which Mpe1 resides. Surprisingly, both the zinc knuckle and the RING finger are needed for RNA-binding activity. Consistent with a role for Mpe1 in ubiquitination, mutation of Mpe1 decreases the association of ubiquitin with Pap1, the poly(A) polymerase, and suppressors of mpe1 mutants are linked to ubiquitin ligases. Furthermore, an inhibitor of ubiquitin-mediated interactions blocks cleavage, demonstrating for the first time a direct role for ubiquitination in mRNA 3'-end processing.
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20
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Williams C. Going against the flow: A case for peroxisomal protein export. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:1386-92. [DOI: 10.1016/j.bbamcr.2014.04.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Revised: 04/03/2014] [Accepted: 04/07/2014] [Indexed: 10/25/2022]
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21
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Bai B, Chen PC, Hales CM, Wu Z, Pagala V, High AA, Levey AI, Lah JJ, Peng J. Integrated approaches for analyzing U1-70K cleavage in Alzheimer's disease. J Proteome Res 2014; 13:4526-34. [PMID: 24902715 PMCID: PMC4227550 DOI: 10.1021/pr5003593] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
![]()
The
accumulation of pathologic protein fragments is common in neurodegenerative
disorders. We have recently identified in Alzheimer’s disease
(AD) the aggregation of the U1-70K splicing factor and abnormal RNA
processing. Here, we present that U1-70K can be cleaved into an N-terminal
truncation (N40K) in ∼50% of AD cases, and the N40K abundance
is inversely proportional to the total level of U1-70K. To map the
cleavage site, we compared tryptic peptides of N40K and stable isotope
labeled U1-70K by liquid chromatography–tandem mass spectrometry
(MS), revealing that the proteolysis site is located in a highly repetitive
and hydrophilic domain of U1-70K. We then adapted Western blotting
to map the cleavage site in two steps: (i) mass spectrometric analysis
revealing that U1-70K and N40K share the same N-termini and contain
no major modifications; (ii) matching N40K with a series of six recombinant
U1-70K truncations to define the cleavage site within a small region
(Arg300 ± 6 residues). Finally, N40K expression led to substantial
degeneration of rat primary hippocampal neurons. In summary, we combined
multiple approaches to identify the U1-70K proteolytic site and found
that the N40K fragment might contribute to neuronal toxicity in Alzheimer’s
disease.
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Affiliation(s)
- Bing Bai
- Departments of Structural Biology and Developmental Neurobiology, ‡St. Jude Proteomics Facility, St. Jude Children's Research Hospital , Memphis, Tennessee 38105, United States
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22
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The mitochondrial deubiquitinase USP30 opposes parkin-mediated mitophagy. Nature 2014; 510:370-5. [PMID: 24896179 DOI: 10.1038/nature13418] [Citation(s) in RCA: 590] [Impact Index Per Article: 59.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Accepted: 04/28/2014] [Indexed: 01/20/2023]
Abstract
Cells maintain healthy mitochondria by degrading damaged mitochondria through mitophagy; defective mitophagy is linked to Parkinson's disease. Here we report that USP30, a deubiquitinase localized to mitochondria, antagonizes mitophagy driven by the ubiquitin ligase parkin (also known as PARK2) and protein kinase PINK1, which are encoded by two genes associated with Parkinson's disease. Parkin ubiquitinates and tags damaged mitochondria for clearance. Overexpression of USP30 removes ubiquitin attached by parkin onto damaged mitochondria and blocks parkin's ability to drive mitophagy, whereas reducing USP30 activity enhances mitochondrial degradation in neurons. Global ubiquitination site profiling identified multiple mitochondrial substrates oppositely regulated by parkin and USP30. Knockdown of USP30 rescues the defective mitophagy caused by pathogenic mutations in parkin and improves mitochondrial integrity in parkin- or PINK1-deficient flies. Knockdown of USP30 in dopaminergic neurons protects flies against paraquat toxicity in vivo, ameliorating defects in dopamine levels, motor function and organismal survival. Thus USP30 inhibition is potentially beneficial for Parkinson's disease by promoting mitochondrial clearance and quality control.
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23
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Lin F, Tan HJ, Guan JS, Lim YP. Divide and conquer: subproteomic approaches toward gastric cancer biomarker and drug target discovery. Expert Rev Proteomics 2014; 11:515-30. [PMID: 24684179 DOI: 10.1586/14789450.2014.904751] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The discovery of biomarkers for early detection and treatment for gastric cancer are two important gaps that proteomics have the potential to fill. Advancements in mass spectrometry, sample preparation and separation strategies are crucial to proteomics-based discoveries and subsequent translations from bench to bedside. A great number of studies exploiting various subproteomic approaches have emerged for higher-resolution analysis (compared with shotgun proteomics) that permit interrogation of different post-translational and subcellular compartmentalized forms of the same proteins as determinants of disease phenotypes. This is a unique and key strength of proteomics over genomics. In this review, the salient features, competitive edges and pitfalls of various subproteomic approaches are discussed. We also highlight valuable insights from several subproteomic studies that have increased our understanding of the molecular etiology of gastric cancer and the findings that led to the discovery of potential biomarkers/drug targets that were otherwise not revealed by conventional shotgun expression proteomics.
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Affiliation(s)
- Fan Lin
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, MD4, level 1, 5 Science Drive 2, Singapore
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24
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Abstract
Ubiquitination is a versatile and dynamic posttranslational modification in cells, regulating almost all cellular events. With rapid developments of affinity capture reagents and high-resolution mass spectrometry, it is now feasible to globally analyze the ubiquitinated proteome (ubiquitome) using quantitative strategies, such as stable isotope labeling with amino acids in cell culture (SILAC). Here we describe in detail a SILAC protocol to profile the ubiquitome in mammalian cells including protein labeling, antibody-based enrichment, and analysis by mass spectrometry.
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Affiliation(s)
- Zhiping Wu
- Department of Structural Biology, St. Jude Proteomics Facility, St Jude Children's Research Hospital, Memphis, TN, 38105, USA
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25
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Donovan LE, Dammer EB, Duong DM, Hanfelt JJ, Levey AI, Seyfried NT, Lah JJ. Exploring the potential of the platelet membrane proteome as a source of peripheral biomarkers for Alzheimer's disease. ALZHEIMERS RESEARCH & THERAPY 2013; 5:32. [PMID: 23764030 PMCID: PMC4054949 DOI: 10.1186/alzrt186] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 05/01/2013] [Accepted: 06/13/2013] [Indexed: 12/16/2022]
Abstract
Introduction Peripheral biomarkers to diagnose Alzheimer's disease (AD) have not been established. Given parallels between neuron and platelet biology, we hypothesized platelet membrane-associated protein changes may differentiate patients clinically defined with probable AD from noncognitive impaired controls. Methods Purified platelets, confirmed by flow cytometry were obtained from individuals before fractionation by ultracentrifugation. Following a comparison of individual membrane fractions by SDS-PAGE for general proteome uniformity, equal protein weight from the membrane fractions for five representative samples from AD and five samples from controls were pooled. AD and control protein pools were further divided into molecular weight regions by one-dimensional SDS-PAGE, prior to digestion in gel. Tryptic peptides were analyzed by reverse-phase liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). Ionized peptide intensities were averaged for each identified protein in the two pools, thereby measuring relative protein abundance between the two membrane protein pools. Log2-transformed ratio (AD/control) of protein abundances fit a normal distribution, thereby permitting determination of significantly changed protein abundances in the AD pool. Results We report a comparative analysis of the membrane-enriched platelet proteome between patients with mild to moderate AD and cognitively normal, healthy subjects. A total of 144 proteins were determined significantly altered in the platelet membrane proteome from patients with probable AD. In particular, secretory (alpha) granule proteins were dramatically reduced in AD. Of these, we confirmed significant reduction of thrombospondin-1 (THBS1) in the AD platelet membrane proteome by immunoblotting. There was a high protein-protein connectivity of proteins in other pathways implicated by proteomic changes to the proteins that define secretory granules. Conclusions Depletion of secretory granule proteins is consistent with a preponderance of post-activated platelets in circulation in AD. Significantly changed pathways implicate additional AD-related defects in platelet glycoprotein synthesis, lipid homeostasis, amyloidogenic proteins, and regulators of protease activity, many of which may be useful plasma membrane-expressed markers for AD. This study highlights the utility of LC-MS/MS to quantify human platelet membrane proteins and suggests that platelets may serve as a source of blood-based biomarkers in neurodegenerative disease.
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Affiliation(s)
- Laura E Donovan
- Department of Neurology and Center for Neurodegenerative Disease, Emory University School of Medicine, 615 Michael Street NE, Atlanta, Georgia 30322, USA
| | - Eric B Dammer
- Department of Human Genetics, Emory University School of Medicine, 615 Michael Street NE, Atlanta, Georgia 30322, USA
| | - Duc M Duong
- Department of Biochemistry, Emory University School of Medicine, 1510 Clifton Road NE, Atlanta, Georgia 30322, USA
| | - John J Hanfelt
- Department of Biostatistics and Bioinformatics, Emory University School of Medicine, 1518 Clifton Road NE, Atlanta, Georgia 30322, USA
| | - Allan I Levey
- Department of Neurology and Center for Neurodegenerative Disease, Emory University School of Medicine, 615 Michael Street NE, Atlanta, Georgia 30322, USA
| | - Nicholas T Seyfried
- Department of Neurology and Center for Neurodegenerative Disease, Emory University School of Medicine, 615 Michael Street NE, Atlanta, Georgia 30322, USA ; Department of Biochemistry, Emory University School of Medicine, 1510 Clifton Road NE, Atlanta, Georgia 30322, USA
| | - James J Lah
- Department of Neurology and Center for Neurodegenerative Disease, Emory University School of Medicine, 615 Michael Street NE, Atlanta, Georgia 30322, USA
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26
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Polge C, Uttenweiler-Joseph S, Leulmi R, Heng AE, Burlet-Schiltz O, Attaix D, Taillandier D. Deciphering the ubiquitin proteome: Limits and advantages of high throughput global affinity purification-mass spectrometry approaches. Int J Biochem Cell Biol 2013; 45:2136-46. [PMID: 23764619 DOI: 10.1016/j.biocel.2013.05.031] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Revised: 05/24/2013] [Accepted: 05/26/2013] [Indexed: 11/19/2022]
Abstract
Ubiquitination is a posttranslational modification of proteins that involves the covalent attachment of ubiquitin, either as a single moiety or as polymers. This process controls almost every cellular metabolic pathway through a variety of combinations of linkages. Mass spectrometry now allows high throughput approaches for the identification of the thousands of ubiquitinated proteins and of their ubiquitination sites. Despite major technological improvements in mass spectrometry in terms of sensitivity, resolution and acquisition speed, the use of efficient purification methods of ubiquitinated proteins prior to mass spectrometry analysis is critical to achieve an efficient characterization of the ubiquitome. This critical step is achieved using different approaches that possess advantages and pitfalls. Here, we discuss the limits that can be encountered when deciphering the ubiquitome. This article is part of a Directed Issue entitled: Molecular basis of muscle wasting.
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Affiliation(s)
- Cécile Polge
- INRA, UMR 1019, UNH, CRNH Auvergne, F-63122 Saint Genès Champanelle, France
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27
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Chicooree N, Connolly Y, Tan CT, Malliri A, Li Y, Smith DL, Griffiths JR. Enhanced detection of ubiquitin isopeptides using reductive methylation. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2013; 24:421-30. [PMID: 23361369 DOI: 10.1007/s13361-012-0538-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Revised: 11/05/2012] [Accepted: 11/06/2012] [Indexed: 06/01/2023]
Abstract
Identification of ubiquitination (Ub) sites is of great interest due to the critical roles that the modification plays in cellular regulation. Current methods using mass spectrometry rely upon tryptic isopeptide diglycine tag generation followed by database searching. We present a novel approach to ubiquitin detection based upon the dimethyl labeling of isopeptide N-termini glycines. Ubiquitinated proteins were digested with trypsin and the resulting peptide mixture was derivatized using formaldehyde-D2 solution and sodium cyanoborohydride. The dimethylated peptide mixtures were next separated by liquid chromatography and analyzed on a quadrupole-TOF based mass spectrometer. Diagnostic b2' and a1' ions released from the isopeptide N-terminus upon collision-induced dissociation (CID) were used to spectrally improve the identification of ubiquitinated isopeptides. Proof of principle was established by application to a ubiquitinated protein tryptic digest spiked into a six-protein mix digest background. Extracted ion chromatograms of the a1' and b2' diagnostic product ions from the diglycine tag resulted in a significant reduction in signal complexity and demonstrated a selectivity towards the identification of diglycine branched isopeptides. The method was further shown to be capable of identifying diglycine isopeptides resulting from in-gel tryptic digests of ubiquitin enriched material from a His-Ub transfected cell line. We envisage that these ions may be utilized in global ubiquitination studies with post-acquisition MS/MS (or MSe) data interrogation on high resolution hybrid mass spectrometers. ᅟ
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Affiliation(s)
- Navin Chicooree
- Paterson Institute for Cancer Research, University of Manchester, Manchester, M20 4BX, UK
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Kang PJ, Hood-DeGrenier JK, Park HO. Coupling of septins to the axial landmark by Bud4 in budding yeast. J Cell Sci 2013; 126:1218-26. [PMID: 23345395 DOI: 10.1242/jcs.118521] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cells of the budding yeast Saccharomyces cerevisiae select a site for polarized growth in a specific pattern that depends on their cell type. Haploid a and α cells bud in the axial budding pattern, which requires assembly of a landmark that includes the Bud4 protein. To understand how an axial bud site is established, we performed a structure-function analysis of Bud4. Bud4 contains DUF1709 (domain of unknown function), which is similar to a part of the anillin-homology domain, and a putative Pleckstrin homology (PH) domain near to its C terminus. Although its localization depends on septins, a conserved family of GTP-binding proteins, Bud4 is necessary for the stable inheritance of septin rings during cell division. Although some anillins interact directly with septins, we find that neither DUF1709 nor the PH domain is necessary for targeting Bud4 to the mother-bud neck. Instead, this C-terminal region is crucial for association of Bud4 with Bud3 and other components of the axial landmark. Remarkably, septins colocalize with Bud4 mutant proteins that lack these C-terminal domains, forming an arc or a single ring instead of a double ring during and after cytokinesis. Interestingly, overexpression of Bud4 also induces formation of extra Bud4 rings and arcs that are associated with septins. Analyses of a series of bud4 truncation mutants suggest that at least two domains in the central region play a redundant role in targeting Bud4 to the mother-bud neck and are thus likely to interact with septins. Taken together, these results indicate that Bud4 functions as a platform that links septins to the axial landmark.
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Affiliation(s)
- Pil Jung Kang
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA
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Low TY, Magliozzi R, Guardavaccaro D, Heck AJR. Unraveling the ubiquitin-regulated signaling networks by mass spectrometry-based proteomics. Proteomics 2012; 13:526-37. [PMID: 23019148 DOI: 10.1002/pmic.201200244] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Revised: 08/08/2012] [Accepted: 08/22/2012] [Indexed: 11/11/2022]
Abstract
Ubiquitin (Ub) is a small protein modifier that is covalently attached to the ε-amino group of lysine residues of protein substrates, generally targeting them for degradation. Due to the emergence of specific anti-diglycine (-GG) antibodies and the improvement in MS, it is now possible to identify more than 10 000 ubiquitylated sites in a single proteomics study. Besides cataloging ubiquitylated sites, it is equally important to unravel the biological relationship between ubiquitylated substrates and the ubiquitin conjugation machinery. Relevant to this, we discuss the role of affinity purification-MS (AP-MS), in characterizing E3 ligase-substrate complexes. Recently, such strategies have also been adapted to screen for binding partners of both deubiquitylating enzymes (DUBs) and ubiquitin-binding domains (UBDs). The complexity of the "ubiquitome" is further expanded by the fact that Ub itself can be ubiquitylated at any of its seven lysine residues forming polyubiquitin (polyUb), thus diversifying its lengths and topologies to suit a variety of molecular recognition processes. Therefore, applying MS to study polyUb linkages is also becoming an emerging and important area. Finally, we discuss the future of MS-based proteomics in answering important questions with respect to ubiquitylation.
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Affiliation(s)
- Teck Yew Low
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands.
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Na CH, Jones DR, Yang Y, Wang X, Xu Y, Peng J. Synaptic protein ubiquitination in rat brain revealed by antibody-based ubiquitome analysis. J Proteome Res 2012; 11:4722-32. [PMID: 22871113 DOI: 10.1021/pr300536k] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Protein ubiquitination is an essential post-translational modification regulating neurodevelopment, synaptic plasticity, learning, and memory, and its dysregulation contributes to the pathogenesis of neurological diseases. Here we report a systematic analysis of ubiquitinated proteome (ubiquitome) in rat brain using a newly developed monoclonal antibody that recognizes the diglycine tag on lysine residues in trypsinized peptides (K-GG peptides). Initial antibody specificity analysis showed that the antibody can distinguish K-GG peptides from linear GG peptides or pseudo K-GG peptides derived from iodoacetamide. To evaluate the false discovery rate of K-GG peptide matches during database search, we introduced a null experiment using bacterial lysate that contains no such peptides. The brain ubiquitome was then analyzed by this antibody enrichment with or without strong cation exchange (SCX) prefractionation. During SCX chromatography, although the vast majority of K-GG peptides were detected in the fractions containing at least three positive charged peptides, specific K-GG peptides with two positive charges (e.g., protein N-terminal acetylated and C-terminal non-K/R peptides) were also identified in early fractions. The reliability of C-terminal K-GG peptides was also extensively investigated. Finally, we collected a data set of 1786 K-GG sites on 2064 peptides in 921 proteins and estimated their abundance by spectral counting. The study reveals a wide range of ubiquitination events on key components in presynaptic region (e.g., Bassoon, NSF, SNAP25, synapsin, synaptotagmin, and syntaxin) and postsynaptic density (e.g., PSD-95, GKAP, CaMKII, as well as receptors for NMDA, AMPA, GABA, serotonin, and acetylcholine). We also determined ubiquitination sites on amyloid precursor protein and alpha synuclein that are thought to be causative agents in Alzhermer's and Parkinson's disorders, respectively. As K-GG peptides can also be produced from Nedd8 or ISG15 modified proteins, we quantified these proteins in the brain and found that their levels are less than 2% of ubiquitin. Together, this study demonstrates that a large number of neuronal proteins are modified by ubiquitination and provides a feasible method for profiling the ubiquitome in the brain.
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Affiliation(s)
- Chan Hyun Na
- Departments of Structural Biology and Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA
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31
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Quantitative proteomics to decipher ubiquitin signaling. Amino Acids 2012; 43:1049-60. [PMID: 22821265 DOI: 10.1007/s00726-012-1286-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Accepted: 04/03/2012] [Indexed: 12/21/2022]
Abstract
Ubiquitin signaling plays an essential role in controlling cellular processes in eukaryotes, and the impairment of ubiquitin regulation contributes to the pathogenesis of a wide range of human diseases. During the last decade, mass spectrometry-based proteomics has emerged as an indispensable approach for identifying the ubiquitinated proteome (ubiquitinome), ubiquitin modification sites, the linkages of complex ubiquitin chains, as well as the interactome of ubiquitin enzymes. In particular, implementation of quantitative strategies allows the detection of dynamic changes in the ubiquitinome, enhancing the ability to differentiate between function-relevant protein targets and false positives arising from biological and experimental variations. The profiling of total cell lysate and the ubiquitinated proteome in the same sets of samples has become a powerful tool, revealing a subset of substrates that are modulated by specific physiological and pathological conditions, such as gene mutations in ubiquitin signaling. This strategy is equally useful for dissecting the pathways of ubiquitin-like proteins.
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Bustos D, Bakalarski CE, Yang Y, Peng J, Kirkpatrick DS. Characterizing ubiquitination sites by peptide-based immunoaffinity enrichment. Mol Cell Proteomics 2012; 11:1529-40. [PMID: 22729469 DOI: 10.1074/mcp.r112.019117] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Advances in high resolution tandem mass spectrometry and peptide enrichment technologies have transformed the field of protein biochemistry by enabling analysis of end points that have traditionally been inaccessible to molecular and biochemical techniques. One field benefitting from this research has been the study of ubiquitin, a 76-amino acid protein that functions as a covalent modifier of other proteins. Seminal work performed decades ago revealed that trypsin digestion of a branched protein structure known as A24 yielded an enigmatic diglycine signature bound to a lysine residue in histone 2A. With the onset of mass spectrometry proteomics, identification of K-GG-modified peptides has emerged as an effective way to map the position of ubiquitin modifications on a protein of interest and to quantify the extent of substrate ubiquitination. The initial identification of K-GG peptides by mass spectrometry initiated a flurry of work aimed at enriching these post-translationally modified peptides for identification and quantification en masse. Recently, immunoaffinity reagents have been reported that are capable of capturing K-GG peptides from ubiquitin and its thousands of cellular substrates. Here we focus on the history of K-GG peptides, their identification by mass spectrometry, and the utility of immunoaffinity reagents for studying the mechanisms of cellular regulation by ubiquitin.
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Affiliation(s)
- Daisy Bustos
- Department of Protein Chemistry, Genentech, Inc., South San Francisco, California 94080, USA
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Coaggregation of RNA-binding proteins in a model of TDP-43 proteinopathy with selective RGG motif methylation and a role for RRM1 ubiquitination. PLoS One 2012; 7:e38658. [PMID: 22761693 PMCID: PMC3380899 DOI: 10.1371/journal.pone.0038658] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Accepted: 05/08/2012] [Indexed: 12/13/2022] Open
Abstract
TAR DNA-binding protein 43 (TDP-43) is a major component within ubiquitin-positive inclusions of a number of neurodegenerative diseases that increasingly are considered as TDP-43 proteinopathies. Identities of other inclusion proteins associated with TDP-43 aggregation remain poorly defined. In this study, we identify and quantitate 35 co-aggregating proteins in the detergent-resistant fraction of HEK-293 cells in which TDP-43 or a particularly aggregate prone variant, TDP-S6, were enriched following overexpression, using stable isotope-labeled (SILAC) internal standards and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). We also searched for differential post-translational modification (PTM) sites of ubiquitination. Four sites of ubiquitin conjugation to TDP-43 or TDP-S6 were confirmed by dialkylated GST-TDP-43 external reference peptides, occurring on or near RNA binding motif (RRM) 1. RRM-containing proteins co-enriched in cytoplasmic granular structures in HEK-293 cells and primary motor neurons with insoluble TDP-S6, including cytoplasmic stress granule associated proteins G3BP, PABPC1, and eIF4A1. Proteomic evidence for TDP-43 co-aggregation with paraspeckle markers RBM14, PSF and NonO was also validated by western blot and by immunocytochemistry in HEK-293 cells. An increase in peptides from methylated arginine-glycine-glycine (RGG) RNA-binding motifs of FUS/TLS and hnRNPs was found in the detergent-insoluble fraction of TDP-overexpressing cells. Finally, TDP-43 and TDP-S6 detergent-insoluble species were reduced by mutagenesis of the identified ubiquitination sites, even following oxidative or proteolytic stress. Together, these findings define some of the aggregation partners of TDP-43, and suggest that TDP-43 ubiquitination influences TDP-43 oligomerization.
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Qureshi N, Morrison DC, Reis J. Proteasome protease mediated regulation of cytokine induction and inflammation. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1823:2087-93. [PMID: 22728331 DOI: 10.1016/j.bbamcr.2012.06.016] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Revised: 06/05/2012] [Accepted: 06/07/2012] [Indexed: 01/16/2023]
Abstract
We have previously demonstrated that proteasome serves as a central regulator of inflammation and macrophage function. Until recently, proteasomes have generally been considered to play a relatively passive role in the regulation of cellular activity, i.e., any ubiquitinated protein was considered to be in discriminatively targeted for degradation by the proteasome. We have demonstrated, however, by using specific proteasome protease inhibitors and knockout mice lacking specific components of immunoproteasomes, that proteasomes (containing X, Y, and Z protease subunits) and immunoproteasomes (containing LMP7, LMP2, and LMP10 protease subunits) have well-defined functions in cytokine induction and inflammation based on their individual protease activities. We have also shown that LPS-TLR mediated signaling in the murine RAW 264.7 macrophage cell line results in the replacement of macrophage immunoproteasomal subunits. Such modifications serve as pivotal regulators of LPS-induced inflammation. Our findings support the relatively novel concept that defects in structure/function of proteasome protease subunits caused by genetic disorders, aging, diet, or drugs may well have the potential to contribute to modulation of proteasome activity. Of particular relevance, we have identified quercetin and resveratrol, significant constituents present in berries and in red wine respectively, as two novel proteasome inhibitors that have been previously implicated as disease-modifying natural products. We posit that natural proteasome inhibitors/activators can potentially be used as therapeutic response modifiers to prevent/treat diseases through pathways involving the ubiquitin-proteasome pathway (UP-pathway), which likely functions as a master regulator involved in control of overall inflammatory responses. This article is part of a Special Issue entitled: Ubiquitin Drug Discovery and Diagnostics.
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Affiliation(s)
- Nilofer Qureshi
- Department of Basic Medical Sciences, University of Missouri, Kansas City, MO 64108, USA.
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Udeshi ND, Mani DR, Eisenhaure T, Mertins P, Jaffe JD, Clauser KR, Hacohen N, Carr SA. Methods for quantification of in vivo changes in protein ubiquitination following proteasome and deubiquitinase inhibition. Mol Cell Proteomics 2012; 11:148-59. [PMID: 22505724 DOI: 10.1074/mcp.m111.016857] [Citation(s) in RCA: 127] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Ubiquitination plays a key role in protein degradation and signal transduction. Ubiquitin is a small protein modifier that is adducted to lysine residues by the combined function of E1, E2, and E3 enzymes and is removed by deubiquitinating enzymes. Characterization of ubiquitination sites is important for understanding the role of this modification in cellular processes and disease. However, until recently, large-scale characterization of endogenous ubiquitination sites has been hampered by the lack of efficient enrichment techniques. The introduction of antibodies that specifically recognize peptides with lysine residues that harbor a di-glycine remnant (K-ε-GG) following tryptic digestion has dramatically improved the ability to enrich and identify ubiquitination sites from cellular lysates. We used this enrichment technique to study the effects of proteasome inhibition by MG-132 and deubiquitinase inhibition by PR-619 on ubiquitination sites in human Jurkat cells by quantitative high performance mass spectrometry. Minimal fractionation of digested lysates prior to immunoaffinity enrichment increased the yield of K-ε-GG peptides three- to fourfold resulting in detection of up to ~3300 distinct K-GG peptides in SILAC triple encoded experiments starting from 5 mg of protein per label state. In total, we identify 5533 distinct K-ε-GG peptides of which 4907 were quantified in this study, demonstrating that the strategy presented is a practical approach to perturbational studies in cell systems. We found that proteasome inhibition by MG-132 and deubiquitinase inhibition by PR-619 induces significant changes to the ubiquitin landscape, but that not all ubiquitination sites regulated by MG-132 and PR-619 are likely substrates for the ubiquitin-proteasome system. Additionally, we find that the proteasome and deubiquitinase inhibitors studied induced only minor changes in protein expression levels regardless of the extent of regulation induced at the ubiquitin site level. We attribute this finding to the low stoichiometry of the majority ubiquitination sites identified in this study.
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Affiliation(s)
- Namrata D Udeshi
- Broad Institute of MIT and Harvard, 7 Cambridge Center, Cambridge, Massachusetts 02142, USA
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Seyfried NT, Gozal YM, Donovan LE, Herskowitz JH, Dammer EB, Xia Q, Ku L, Chang J, Duong DM, Rees HD, Cooper DS, Glass JD, Gearing M, Tansey MG, Lah JJ, Feng Y, Levey AI, Peng J. Quantitative analysis of the detergent-insoluble brain proteome in frontotemporal lobar degeneration using SILAC internal standards. J Proteome Res 2012; 11:2721-38. [PMID: 22416763 DOI: 10.1021/pr2010814] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
A hallmark of neurodegeneration is the aggregation of disease related proteins that are resistant to detergent extraction. In the major pathological subtype of frontotemporal lobar degeneration (FTLD), modified TAR-DNA binding protein 43 (TDP-43), including phosphorylated, ubiquitinated, and proteolytically cleaved forms, is enriched in detergent-insoluble fractions from post-mortem brain tissue. Additional proteins that accumulate in the detergent-insoluble FTLD brain proteome remain largely unknown. In this study, we used proteins from stable isotope-labeled (SILAC) human embryonic kidney 293 cells (HEK293) as internal standards for peptide quantitation across control and FTLD insoluble brain proteomes. Proteins were identified and quantified by liquid-chromatography coupled with tandem mass spectrometry (LC-MS/MS) and 21 proteins were determined to be enriched in FTLD using SILAC internal standards. In parallel, label-free quantification of only the unlabeled brain derived peptides by spectral counts (SC) and G-test analysis identified additional brain-specific proteins significantly enriched in disease. Several proteins determined to be enriched in FTLD using SILAC internal standards were not considered significant by G-test due to their low total number of SC. However, immunoblotting of FTLD and control samples confirmed enrichment of these proteins, highlighting the utility of SILAC internal standard to quantify low-abundance proteins in brain. Of these, the RNA binding protein PTB-associated splicing factor (PSF) was further characterized because of structural and functional similarities to TDP-43. Full-length PSF and shorter molecular weight fragments, likely resulting from proteolytic cleavage, were enriched in FTLD cases. Immunohistochemical analysis of PSF revealed predominately nuclear localization in control and FTLD brain tissue and was not associated with phosphorylated pathologic TDP-43 neuronal inclusions. However, in a subset of FTLD cases, PSF was aberrantly localized to the cytoplasm of oligodendrocytes. These data raise the possibility that PSF directed RNA processes in oligodendrocytes are altered in neurodegenerative disease.
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Affiliation(s)
- Nicholas T Seyfried
- Department of Biochemistry, Center for Neurodegenerative Disease, School of Medicine, Emory University, Atlanta, Georgia 30322, USA.
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Donovan LE, Higginbotham L, Dammer EB, Gearing M, Rees H, Xia Q, Duong D, Seyfried NT, Lah JJ, Levey AI. Analysis of a membrane-enriched proteome from postmortem human brain tissue in Alzheimer's disease. Proteomics Clin Appl 2012; 6:201-11. [PMID: 22532456 PMCID: PMC3338199 DOI: 10.1002/prca.201100068] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Accepted: 12/19/2011] [Indexed: 12/29/2022]
Abstract
PURPOSE The present study is a discovery mode proteomics analysis of the membrane-enriched fraction of postmortem brain tissue from Alzheimer's disease (AD) and control cases. This study aims to validate a method to identify new proteins that could be involved in the pathogenesis of AD and potentially serve as disease biomarkers. EXPERIMENTAL DESIGN Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to analyze the membrane-enriched fraction of human postmortem brain tissue from five AD and five control cases of similar age. Biochemical validation of specific targets was performed by immunoblotting. RESULTS One thousand seven hundred and nine proteins were identified from the membrane-enriched fraction of frontal cortex. Label-free quantification by spectral counting and G-test analysis identified 13 proteins that were significantly changed in disease. In addition to Tau (MAPT), two additional proteins found to be enriched in AD, ubiquitin carboxy-terminal hydrolase 1 (UCHL1), and syntaxin-binding protein 1 (Munc-18), were validated through immunoblotting. DISCUSSION AND CLINICAL RELEVANCE: Proteomic analysis of the membrane-enriched fraction of postmortem brain tissue identifies proteins biochemically altered in AD. Further analysis of this subproteome may help elucidate mechanisms behind AD pathogenesis and provide new sources of biomarkers.
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Affiliation(s)
- Laura E. Donovan
- Departments of Neurology, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Lenora Higginbotham
- Departments of Neurology, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Eric B. Dammer
- Human Genetics, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Marla Gearing
- Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, Georgia 30322
- Experimental Pathology, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Howard Rees
- Departments of Neurology, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Qiangwei Xia
- Human Genetics, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Duc Duong
- Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322
- Neuroscience Proteomics Core Facility. Emory University School of Medicine, Atlanta, Georgia 30322
| | - Nicholas T. Seyfried
- Departments of Neurology, Emory University School of Medicine, Atlanta, Georgia 30322
- Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322
- Neuroscience Proteomics Core Facility. Emory University School of Medicine, Atlanta, Georgia 30322
| | - James J. Lah
- Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, Georgia 30322
- Departments of Neurology, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Allan I. Levey
- Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, Georgia 30322
- Departments of Neurology, Emory University School of Medicine, Atlanta, Georgia 30322
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Abstract
Protein modification by ubiquitin (Ub) is one of the most common posttranslational events in eukaryotic cells. Ubiquitinated proteins are destined to various fates such as proteasomal degradation, protein trafficking, DNA repair, and immune response. In the last decade, vast improvements of mass spectrometry make it feasible to analyze the minute amount of ubiquitinated components in vivo. When combined with quantitative strategies, such as stable isotope labeling with amino acids in cell culture (SILAC), it is capable of profiling ubiquitinated proteome under different experimental conditions. Here, we describe a procedure to perform such a study, including differential protein labeling by the SILAC method, enrichment of ubiquitinated species, mass spectrometric analysis, and quality control to reduce false positives. The potential challenges and limitations of the procedure are also discussed.
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Affiliation(s)
- Chan Hyun Na
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, USA
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Abstract
Protein ubiquitylation is a highly conserved, central mechanism to regulate cellular events in all eukaryotes, such as proteasomal degradation, protein trafficking, DNA repair, synaptic plasticity, and immune response. The consequence of protein ubiquitylation is modulated by the structure of ubiquitin (Ub) moiety attached on the substrates, including ubiquitin monomer and diverse polyubiquitin chains with different linkages (N-terminus, K6, K11, K27, K29, K33, K48, and K63). The development of ubiquitin-enrichment strategies coupled with sensitive mass spectrometry enables direct analysis of ubiquitylated proteins in cells, providing an invaluable tool for ubiquitin research. In this chapter, we describe recent technology updates for analyzing tissue-specific ubiquitin conjugates in transgenic models, as well as targeted proteomics methods for quantifying different polyubiquitin chain linkages in any type of -samples, including human tissues.
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Han Y, Lee H, Park JC, Yi GS. E3Net: a system for exploring E3-mediated regulatory networks of cellular functions. Mol Cell Proteomics 2011; 11:O111.014076. [PMID: 22199232 DOI: 10.1074/mcp.o111.014076] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ubiquitin-protein ligase (E3) is a key enzyme targeting specific substrates in diverse cellular processes for ubiquitination and degradation. The existing findings of substrate specificity of E3 are, however, scattered over a number of resources, making it difficult to study them together with an integrative view. Here we present E3Net, a web-based system that provides a comprehensive collection of available E3-substrate specificities and a systematic framework for the analysis of E3-mediated regulatory networks of diverse cellular functions. Currently, E3Net contains 2201 E3s and 4896 substrates in 427 organisms and 1671 E3-substrate specific relations between 493 E3s and 1277 substrates in 42 organisms, extracted mainly from MEDLINE abstracts and UniProt comments with an automatic text mining method and additional manual inspection and partly from high throughput experiment data and public ubiquitination databases. The significant functions and pathways of the extracted E3-specific substrate groups were identified from a functional enrichment analysis with 12 functional category resources for molecular functions, protein families, protein complexes, pathways, cellular processes, cellular localization, and diseases. E3Net includes interactive analysis and navigation tools that make it possible to build an integrative view of E3-substrate networks and their correlated functions with graphical illustrations and summarized descriptions. As a result, E3Net provides a comprehensive resource of E3s, substrates, and their functional implications summarized from the regulatory network structures of E3-specific substrate groups and their correlated functions. This resource will facilitate further in-depth investigation of ubiquitination-dependent regulatory mechanisms. E3Net is freely available online at http://pnet.kaist.ac.kr/e3net.
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Affiliation(s)
- Youngwoong Han
- Department of Information and Communications Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea
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41
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Affiliation(s)
- Alfred C O Vertegaal
- Department of Molecular Cell Biology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, The Netherlands.
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Kaminska J, Spiess M, Stawiecka-Mirota M, Monkaityte R, Haguenauer-Tsapis R, Urban-Grimal D, Winsor B, Zoladek T. Yeast Rsp5 ubiquitin ligase affects the actin cytoskeleton in vivo and in vitro. Eur J Cell Biol 2011; 90:1016-28. [DOI: 10.1016/j.ejcb.2011.08.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Revised: 08/11/2011] [Accepted: 08/17/2011] [Indexed: 10/16/2022] Open
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Lee KA, Hammerle LP, Andrews PS, Stokes MP, Mustelin T, Silva JC, Black RA, Doedens JR. Ubiquitin ligase substrate identification through quantitative proteomics at both the protein and peptide levels. J Biol Chem 2011; 286:41530-41538. [PMID: 21987572 DOI: 10.1074/jbc.m111.248856] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein ubiquitination is a key regulatory process essential to life at a cellular level; significant efforts have been made to identify ubiquitinated proteins through proteomics studies, but the level of success has not reached that of heavily studied post-translational modifications, such as phosphorylation. HRD1, an E3 ubiquitin ligase, has been implicated in rheumatoid arthritis, but no disease-relevant substrates have been identified. To identify these substrates, we have taken both peptide and protein level approaches to enrich for ubiquitinated proteins in the presence and absence of HRD1. At the protein level, a two-step strategy was taken using cells expressing His(6)-tagged ubiquitin, enriching proteins first based on their ubiquitination and second based on the His tag with protein identification by LC-MS/MS. Application of this method resulted in identification and quantification of more than 400 ubiquitinated proteins, a fraction of which were found to be sensitive to HRD1 and were therefore deemed candidate substrates. In a second approach, ubiquitinated peptides were enriched after tryptic digestion by peptide immunoprecipitation using an antibody specific for the diglycine-labeled internal lysine residue indicative of protein ubiquitination, with peptides and ubiquitination sites identified by LC-MS/MS. Peptide immunoprecipitation resulted in identification of over 1800 ubiquitinated peptides on over 900 proteins in each study, with several proteins emerging as sensitive to HRD1 levels. Notably, significant overlap exists between the HRD1 substrates identified by the protein-based and the peptide-based strategies, with clear cross-validation apparent both qualitatively and quantitatively, demonstrating the effectiveness of both strategies and furthering our understanding of HRD1 biology.
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Affiliation(s)
- Kimberly A Lee
- Department of Molecular Sciences, Amgen, Seattle, Washington 98119
| | - Lisa P Hammerle
- Department of Inflammation, Amgen, Seattle, Washington 98119
| | - Paul S Andrews
- Department of Lead Discovery, Amgen, Cambridge, Massachusetts 02142
| | | | - Tomas Mustelin
- Department of Inflammation, Amgen, Seattle, Washington 98119
| | - Jeffrey C Silva
- Cell Signaling Technology Inc., Danvers, Massachusetts 01923
| | - Roy A Black
- Department of Inflammation, Amgen, Seattle, Washington 98119
| | - John R Doedens
- Department of Inflammation, Amgen, Seattle, Washington 98119.
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Shi Y, Xu P, Qin J. Ubiquitinated proteome: ready for global? Mol Cell Proteomics 2011; 10:R110.006882. [PMID: 21339389 PMCID: PMC3098603 DOI: 10.1074/mcp.r110.006882] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Revised: 02/15/2011] [Indexed: 01/09/2023] Open
Abstract
Ubiquitin (Ub) is a small and highly conserved protein that can covalently modify protein substrates. Ubiquitination is one of the major post-translational modifications that regulate a broad spectrum of cellular functions. The advancement of mass spectrometers as well as the development of new affinity purification tools has greatly expedited proteome-wide analysis of several post-translational modifications (e.g. phosphorylation, glycosylation, and acetylation). In contrast, large-scale profiling of lysine ubiquitination remains a challenge. Most recently, new Ub affinity reagents such as Ub remnant antibody and tandem Ub binding domains have been developed, allowing for relatively large-scale detection of several hundreds of lysine ubiquitination events in human cells. Here we review different strategies for the identification of ubiquitination site and discuss several issues associated with data analysis. We suggest that careful interpretation and orthogonal confirmation of MS spectra is necessary to minimize false positive assignments by automatic searching algorithms.
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Affiliation(s)
- Yi Shi
- From the ‡Center for Molecular Discovery, Verna and Marrs McLean Department of Biochemistry and Molecular Biology
| | - Ping Xu
- ¶State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, Beijing, P. R. China
| | - Jun Qin
- From the ‡Center for Molecular Discovery, Verna and Marrs McLean Department of Biochemistry and Molecular Biology
- §Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA and
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Ziv I, Matiuhin Y, Kirkpatrick DS, Erpapazoglou Z, Leon S, Pantazopoulou M, Kim W, Gygi SP, Haguenauer-Tsapis R, Reis N, Glickman MH, Kleifeld O. A perturbed ubiquitin landscape distinguishes between ubiquitin in trafficking and in proteolysis. Mol Cell Proteomics 2011; 10:M111.009753. [PMID: 21427232 PMCID: PMC3098606 DOI: 10.1074/mcp.m111.009753] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Any of seven lysine residues on ubiquitin can serve as the base for chain-extension, resulting in a sizeable spectrum of ubiquitin modifications differing in chain length or linkage type. By optimizing a procedure for rapid lysis, we charted the profile of conjugated cellular ubiquitin directly from whole cell extract. Roughly half of conjugated ubiquitin (even at high molecular weights) was nonextended, consisting of monoubiquitin modifications and chain terminators (endcaps). Of extended ubiquitin, the primary linkages were via Lys48 and Lys63. All other linkages were detected, contributing a relatively small portion that increased at lower molecular weights. In vivo expression of lysineless ubiquitin (K0 Ub) perturbed the ubiquitin landscape leading to elevated levels of conjugated ubiquitin, with a higher mono-to-poly ratio. Affinity purification of these trapped conjugates identified a comprehensive list of close to 900 proteins including novel targets. Many of the proteins enriched by K0 ubiquitination were membrane-associated, or involved in cellular trafficking. Prime among them are components of the ESCRT machinery and adaptors of the Rsp5 E3 ubiquitin ligase. Ubiquitin chains associated with these substrates were enriched for Lys63 linkages over Lys48, indicating that K0 Ub is unevenly distributed throughout the ubiquitinome. Biological assays validated the interference of K0 Ub with protein trafficking and MVB sorting, minimally affecting Lys48-dependent turnover of proteasome substrates. We conclude that despite the shared use of the ubiquitin molecule, the two branches of the ubiquitin machinery—the ubiquitin-proteasome system and the ubiquitin trafficking system—were unevenly perturbed by expression of K0 ubiquitin.
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Affiliation(s)
- Inbal Ziv
- Department of Biology, Technion Israel institute of Technology, Haifa 32000, Israel
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46
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Dammer EB, Na CH, Xu P, Seyfried NT, Duong DM, Cheng D, Gearing M, Rees H, Lah JJ, Levey AI, Rush J, Peng J. Polyubiquitin linkage profiles in three models of proteolytic stress suggest the etiology of Alzheimer disease. J Biol Chem 2011; 286:10457-65. [PMID: 21278249 DOI: 10.1074/jbc.m110.149633] [Citation(s) in RCA: 135] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Polyubiquitin chains on substrates are assembled through any of seven lysine residues or the N terminus of ubiquitin (Ub), generating diverse linkages in the chain structure. PolyUb linkages regulate the fate of modified substrates, but their abundance and function in mammalian cells are not well studied. We present a mass spectrometry-based method to measure polyUb linkages directly from total lysate of mammalian cells. In HEK293 cells, the level of polyUb linkages was found to be 52% (Lys(48)), 38% (Lys(63)), 8% (Lys(29)), 2% (Lys(11)), and 0.5% or less for linear, Lys(6), Lys(27), and Lys(33) linkages. Tissue specificity of these linkages was examined in mice fully labeled by heavy stable isotopes (i.e. SILAC mice). Moreover, we profiled the Ub linkages in brain tissues from patients of Alzheimer disease with or without concurrent Lewy body disease as well as three cellular models of proteolytic stress: proteasome deficiency, lysosome deficiency, and heat shock. The data support that polyUb chains linked through Lys(6), Lys(11), Lys(27), Lys(29), and Lys(48) mediate proteasomal degradation, whereas Lys(63) chains are preferentially involved in the lysosomal pathway. Mixed linkages, including Lys(48), may also contribute to lysosomal targeting, as both Lys(63) and Lys(48) linkages are colocalized in LC3-labeled autophagosomes. Interestingly, heat shock treatment augments Lys(11), Lys(48), and Lys(63) but not Lys(29) linkages, and this unique pattern is similar to that in the profiled neurodegenerative cases. We conclude that different polyUb linkages play distinct roles under the three proteolytic stress conditions, and protein folding capacity in the heat shock responsive pathway might be more affected in Alzheimer disease.
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Affiliation(s)
- Eric B Dammer
- Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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47
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Leach MD, Stead DA, Argo E, MacCallum DM, Brown AJP. Molecular and proteomic analyses highlight the importance of ubiquitination for the stress resistance, metabolic adaptation, morphogenetic regulation and virulence of Candida albicans. Mol Microbiol 2011; 79:1574-93. [PMID: 21269335 PMCID: PMC3084552 DOI: 10.1111/j.1365-2958.2011.07542.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Post-translational modifications of proteins play key roles in eukaryotic growth, differentiation and environmental adaptation. In model systems the ubiquitination of specific proteins contributes to the control of cell cycle progression, stress adaptation and metabolic reprogramming. We have combined molecular, cellular and proteomic approaches to examine the roles of ubiquitination in Candida albicans, because little is known about ubiquitination in this major fungal pathogen of humans. Independent null (ubi4/ubi4) and conditional (MET3p-UBI4/ubi4) mutations were constructed at the C. albicans polyubiquitin-encoding locus. These mutants displayed morphological and cell cycle defects, as well as sensitivity to thermal, oxidative and cell wall stresses. Furthermore, ubi4/ubi4 cells rapidly lost viability under starvation conditions. Consistent with these phenotypes, proteins with roles in stress responses (Gnd1, Pst2, Ssb1), metabolism (Acs2, Eno1, Fba1, Gpd2, Pdx3, Pgk1, Tkl1) and ubiquitination (Ubi4, Ubi3, Pre1, Pre3, Rpt5) were among the ubiquitination targets we identified, further indicating that ubiquitination plays key roles in growth, stress responses and metabolic adaptation in C. albicans. Clearly ubiquitination plays key roles in the regulation of fundamental cellular processes that underpin the pathogenicity of this medically important fungus. This was confirmed by the observation that the virulence of C. albicans ubi4/ubi4 cells is significantly attenuated.
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Affiliation(s)
- Michelle D Leach
- School of Medical Sciences, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, UK
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48
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McKay SL, Johnson TL. A bird's-eye view of post-translational modifications in the spliceosome and their roles in spliceosome dynamics. MOLECULAR BIOSYSTEMS 2010; 6:2093-102. [PMID: 20672149 PMCID: PMC4065859 DOI: 10.1039/c002828b] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Pre-mRNA splicing, the removal of noncoding intron sequences from the pre-mRNA, is a critical reaction in eukaryotic gene expression. Pre-mRNA splicing is carried out by a remarkable macromolecular machine, the spliceosome, which undergoes dynamic rearrangements of its RNA and protein components to assemble its catalytic center. While significant progress has been made in describing the "moving parts" of this machine, the mechanisms by which spliceosomal proteins mediate the ordered rearrangements within the spliceosome remain elusive. Here we explore recent evidence from proteomics studies revealing extensive post-translational modification of splicing factors. While the functional significance of most of these modifications remains to be characterized, we describe recent studies in which the roles of specific post-translational modifications of splicing factors have been characterized. These examples illustrate the importance of post-translational modifications in spliceosome dynamics.
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Affiliation(s)
- Susannah L. McKay
- Division of Biological Sciences, Molecular Biology Section MC-0377, 9500 Gilman Drive, La Jolla, CA 92093-0377, USA
| | - Tracy L. Johnson
- Division of Biological Sciences, Molecular Biology Section MC-0377, 9500 Gilman Drive, La Jolla, CA 92093-0377, USA
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49
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Shi Y, Chan DW, Jung SY, Malovannaya A, Wang Y, Qin J. A data set of human endogenous protein ubiquitination sites. Mol Cell Proteomics 2010; 10:M110.002089. [PMID: 20972266 DOI: 10.1074/mcp.m110.002089] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Lysine ubiquitination is an important and versatile protein post-translational modification. Numerous cellular functions are regulated by ubiquitination, suggesting that extensive numbers of proteins, if not all, are modified with ubiquitin at certain times. However, proteome-wide profiling of ubiquitination sites in the mammalian system is technically challenging. We report the design and characterization of an engineered protein affinity reagent for the isolation of ubiquitinated proteins and the identification of ubiquitination sites with mass spectrometry. This recombinant protein consists of four tandem repeats of ubiquitin-associated domain from UBQLN1 fused to a GST tag. We used this GST-qUBA reagent to isolate polyubiquitinated proteins and identified 294 endogenous ubiquitination sites on 223 proteins from human 293T cells without proteasome inhibitors or overexpression of ubiquitin. Mitochondrial proteins constitute 14.7% of this data set, implicating ubiquitination in a wide range of mitochondrial functions.
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Affiliation(s)
- Yi Shi
- Center for Molecular Discovery, Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030, USA
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50
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Franco M, Seyfried NT, Brand AH, Peng J, Mayor U. A novel strategy to isolate ubiquitin conjugates reveals wide role for ubiquitination during neural development. Mol Cell Proteomics 2010; 10:M110.002188. [PMID: 20861518 PMCID: PMC3098581 DOI: 10.1074/mcp.m110.002188] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Ubiquitination has essential roles in neuronal development and function. Ubiquitin proteomics studies on yeast and HeLa cells have proven very informative, but there still is a gap regarding neuronal tissue-specific ubiquitination. In an organism context, direct evidence for the ubiquitination of neuronal proteins is even scarcer. Here, we report a novel proteomics strategy based on the in vivo biotinylation of ubiquitin to isolate ubiquitin conjugates from the neurons of Drosophila melanogaster embryos. We confidently identified 48 neuronal ubiquitin substrates, none of which was yet known to be ubiquitinated. Earlier proteomics and biochemical studies in non-neuronal cell types had identified orthologs to some of those but not to others. The identification here of novel ubiquitin substrates, those with no known ubiquitinated ortholog, suggests that proteomics studies must be performed on neuronal cells to identify ubiquitination pathways not shared by other cell types. Importantly, several of those newly found neuronal ubiquitin substrates are key players in synaptogenesis. Mass spectrometry results were validated by Western blotting to confirm that those proteins are indeed ubiquitinated in the Drosophila embryonic nervous system and to elucidate whether they are mono- or polyubiquitinated. In addition to the ubiquitin substrates, we also identified the ubiquitin carriers that are active during synaptogenesis. Identifying endogenously ubiquitinated proteins in specific cell types, at specific developmental stages, and within the context of a living organism will allow understanding how the tissue-specific function of those proteins is regulated by the ubiquitin system.
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Affiliation(s)
- Maribel Franco
- CIC Biogune, Bizkaia Teknologi Parkea, 48160 Derio, Spain
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