1
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Karpov OA, Stotland A, Raedschelders K, Chazarin B, Ai L, Murray CI, Van Eyk JE. Proteomics of the heart. Physiol Rev 2024; 104:931-982. [PMID: 38300522 PMCID: PMC11381016 DOI: 10.1152/physrev.00026.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 12/25/2023] [Accepted: 01/14/2024] [Indexed: 02/02/2024] Open
Abstract
Mass spectrometry-based proteomics is a sophisticated identification tool specializing in portraying protein dynamics at a molecular level. Proteomics provides biologists with a snapshot of context-dependent protein and proteoform expression, structural conformations, dynamic turnover, and protein-protein interactions. Cardiac proteomics can offer a broader and deeper understanding of the molecular mechanisms that underscore cardiovascular disease, and it is foundational to the development of future therapeutic interventions. This review encapsulates the evolution, current technologies, and future perspectives of proteomic-based mass spectrometry as it applies to the study of the heart. Key technological advancements have allowed researchers to study proteomes at a single-cell level and employ robot-assisted automation systems for enhanced sample preparation techniques, and the increase in fidelity of the mass spectrometers has allowed for the unambiguous identification of numerous dynamic posttranslational modifications. Animal models of cardiovascular disease, ranging from early animal experiments to current sophisticated models of heart failure with preserved ejection fraction, have provided the tools to study a challenging organ in the laboratory. Further technological development will pave the way for the implementation of proteomics even closer within the clinical setting, allowing not only scientists but also patients to benefit from an understanding of protein interplay as it relates to cardiac disease physiology.
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Affiliation(s)
- Oleg A Karpov
- Smidt Heart Institute, Advanced Clinical Biosystems Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States
| | - Aleksandr Stotland
- Smidt Heart Institute, Advanced Clinical Biosystems Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States
| | - Koen Raedschelders
- Smidt Heart Institute, Advanced Clinical Biosystems Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States
| | - Blandine Chazarin
- Smidt Heart Institute, Advanced Clinical Biosystems Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States
| | - Lizhuo Ai
- Smidt Heart Institute, Advanced Clinical Biosystems Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States
| | - Christopher I Murray
- Smidt Heart Institute, Advanced Clinical Biosystems Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States
| | - Jennifer E Van Eyk
- Smidt Heart Institute, Advanced Clinical Biosystems Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States
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2
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Escobar EE, Yang W, Lanzillotti MB, Juetten KJ, Shields S, Siegel D, Zhang YJ, Brodbelt JS. Tracking Inhibition of Human Small C-Terminal Domain Phosphatase 1 Using 193 nm Ultraviolet Photodissociation Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2024; 35:1330-1341. [PMID: 38662915 PMCID: PMC11384422 DOI: 10.1021/jasms.4c00098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2024]
Abstract
Working in tandem with kinases via a dynamic interplay of phosphorylation and dephosphorylation of proteins, phosphatases regulate many cellular processes and thus represent compelling therapeutic targets. Here we leverage ultraviolet photodissociation to shed light on the binding characteristics of two covalent phosphatase inhibitors, T65 and rabeprazole, and their respective interactions with the human small C-terminal domain phosphatase 1 (SCP1) and its single-point mutant C181A, in which a nonreactive alanine replaces one key reactive cysteine. Top-down MS/MS analysis is used to localize the binding of T65 and rabeprazole on the two proteins and estimate the relative reactivities of each cysteine residue.
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Affiliation(s)
| | | | | | | | | | - Dionicio Siegel
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, 9500 Gilman Drive 0741, La Jolla, California 92093, United States
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3
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Varshney N, Mishra AK. Deep Learning in Phosphoproteomics: Methods and Application in Cancer Drug Discovery. Proteomes 2023; 11:proteomes11020016. [PMID: 37218921 DOI: 10.3390/proteomes11020016] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 04/24/2023] [Accepted: 04/25/2023] [Indexed: 05/24/2023] Open
Abstract
Protein phosphorylation is a key post-translational modification (PTM) that is a central regulatory mechanism of many cellular signaling pathways. Several protein kinases and phosphatases precisely control this biochemical process. Defects in the functions of these proteins have been implicated in many diseases, including cancer. Mass spectrometry (MS)-based analysis of biological samples provides in-depth coverage of phosphoproteome. A large amount of MS data available in public repositories has unveiled big data in the field of phosphoproteomics. To address the challenges associated with handling large data and expanding confidence in phosphorylation site prediction, the development of many computational algorithms and machine learning-based approaches have gained momentum in recent years. Together, the emergence of experimental methods with high resolution and sensitivity and data mining algorithms has provided robust analytical platforms for quantitative proteomics. In this review, we compile a comprehensive collection of bioinformatic resources used for the prediction of phosphorylation sites, and their potential therapeutic applications in the context of cancer.
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Affiliation(s)
- Neha Varshney
- Division of Biological Sciences, Department of Cellular and Molecular Medicine, University of California, San Diego, CA 93093, USA
- Ludwig Institute for Cancer Research, La Jolla, CA 92093, USA
| | - Abhinava K Mishra
- Molecular, Cellular and Developmental Biology Department, University of California, Santa Barbara, CA 93106, USA
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4
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Sun B, Kekenes-Huskey PM. Myofilament-associated proteins with intrinsic disorder (MAPIDs) and their resolution by computational modeling. Q Rev Biophys 2023; 56:e2. [PMID: 36628457 PMCID: PMC11070111 DOI: 10.1017/s003358352300001x] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The cardiac sarcomere is a cellular structure in the heart that enables muscle cells to contract. Dozens of proteins belong to the cardiac sarcomere, which work in tandem to generate force and adapt to demands on cardiac output. Intriguingly, the majority of these proteins have significant intrinsic disorder that contributes to their functions, yet the biophysics of these intrinsically disordered regions (IDRs) have been characterized in limited detail. In this review, we first enumerate these myofilament-associated proteins with intrinsic disorder (MAPIDs) and recent biophysical studies to characterize their IDRs. We secondly summarize the biophysics governing IDR properties and the state-of-the-art in computational tools toward MAPID identification and characterization of their conformation ensembles. We conclude with an overview of future computational approaches toward broadening the understanding of intrinsic disorder in the cardiac sarcomere.
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Affiliation(s)
- Bin Sun
- Research Center for Pharmacoinformatics (The State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), Department of Medicinal Chemistry and Natural Medicine Chemistry, College of Pharmacy, Harbin Medical University, Harbin 150081, China
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5
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Marston S, Pinto JR. Suppression of lusitropy as a disease mechanism in cardiomyopathies. Front Cardiovasc Med 2023; 9:1080965. [PMID: 36698941 PMCID: PMC9870330 DOI: 10.3389/fcvm.2022.1080965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 12/19/2022] [Indexed: 01/11/2023] Open
Abstract
In cardiac muscle the action of adrenaline on β1 receptors of heart muscle cells is essential to adjust cardiac output to the body's needs. Adrenergic activation leads to enhanced contractility (inotropy), faster heart rate (chronotropy) and faster relaxation (lusitropy), mainly through activation of protein kinase A (PKA). Efficient enhancement of heart output under stress requires all of these responses to work together. Lusitropy is essential for shortening the heartbeat when heart rate increases. It therefore follows that, if the lusitropic response is not present, heart function under stress will be compromised. Current literature suggests that lusitropy is primarily achieved due to PKA phosphorylation of troponin I (TnI) and phospholamban (PLB). It has been well documented that PKA-induced phosphorylation of TnI releases Ca2+ from troponin C faster and increases the rate of cardiac muscle relaxation, while phosphorylation of PLB increases SERCA activity, speeding up Ca2+ removal from the cytoplasm. In this review we consider the current scientific evidences for the connection between suppression of lusitropy and cardiac dysfunction in the context of mutations in phospholamban and thin filament proteins that are associated with cardiomyopathies. We will discuss what advances have been made into understanding the physiological mechanism of lusitropy due to TnI and PLB phosphorylation and its suppression by mutations and we will evaluate the evidence whether lack of lusitropy is sufficient to cause cardiomyopathy, and under what circumstances, and consider the range of pathologies associated with loss of lusitropy. Finally, we will discuss whether suppressed lusitropy due to mutations in thin filament proteins can be therapeutically restored.
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Affiliation(s)
- Steven Marston
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Jose Renato Pinto
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, FL, United States
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6
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Brown KA, Anderson C, Reilly L, Sondhi K, Ge Y, Eckhardt LL. Proteomic Analysis of the Functional Inward Rectifier Potassium Channel (Kir) 2.1 Reveals Several Novel Phosphorylation Sites. Biochemistry 2021; 60:3292-3301. [PMID: 34676745 DOI: 10.1021/acs.biochem.1c00555] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Membrane proteins represent a large family of proteins that perform vital physiological roles and represent key drug targets. Despite their importance, bioanalytical methods aiming to comprehensively characterize the post-translational modification (PTM) of membrane proteins remain challenging compared to other classes of proteins in part because of their inherent low expression and hydrophobicity. The inward rectifier potassium channel (Kir) 2.1, an integral membrane protein, is critical for the maintenance of the resting membrane potential and phase-3 repolarization of the cardiac action potential in the heart. The importance of this channel to cardiac physiology is highlighted by the recognition of several sudden arrhythmic death syndromes, Andersen-Tawil and short QT syndromes, which are associated with loss or gain of function mutations in Kir2.1, often triggered by changes in the β-adrenergic tone. Therefore, understanding the PTMs of this channel (particularly β-adrenergic tone-driven phosphorylation) is important for arrhythmia prevention. Here, we developed a proteomic method, integrating both top-down (intact protein) and bottom-up (after enzymatic digestion) proteomic analyses, to characterize the PTMs of recombinant wild-type and mutant Kir2.1, successfully mapping five novel sites of phosphorylation and confirming a sixth site. Our study provides a framework for future work to assess the role of PTMs in regulating Kir2.1 functions.
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Affiliation(s)
- Kyle A Brown
- Department of Surgery, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States.,Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Corey Anderson
- Cellular and Molecular Arrhythmia Research Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Louise Reilly
- Cellular and Molecular Arrhythmia Research Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Kunal Sondhi
- Cellular and Molecular Arrhythmia Research Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Ying Ge
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, Wisconsin 53705, United States.,Human Proteomics Program, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin 53705, United States
| | - Lee L Eckhardt
- Cellular and Molecular Arrhythmia Research Program, Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
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7
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Tiambeng TN, Roberts DS, Brown KA, Zhu Y, Chen B, Wu Z, Mitchell SD, Guardado-Alvarez TM, Jin S, Ge Y. Nanoproteomics enables proteoform-resolved analysis of low-abundance proteins in human serum. Nat Commun 2020; 11:3903. [PMID: 32764543 PMCID: PMC7411019 DOI: 10.1038/s41467-020-17643-1] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 07/02/2020] [Indexed: 12/17/2022] Open
Abstract
Top-down mass spectrometry (MS)-based proteomics provides a comprehensive analysis of proteoforms to achieve a proteome-wide understanding of protein functions. However, the MS detection of low-abundance proteins from blood remains an unsolved challenge due to the extraordinary dynamic range of the blood proteome. Here, we develop an integrated nanoproteomics method coupling peptide-functionalized superparamagnetic nanoparticles (NPs) with top-down MS for the enrichment and comprehensive analysis of cardiac troponin I (cTnI), a gold-standard cardiac biomarker, directly from serum. These NPs enable the sensitive enrichment of cTnI (<1 ng/mL) with high specificity and reproducibility, while simultaneously depleting highly abundant proteins such as human serum albumin (>1010 more abundant than cTnI). We demonstrate that top-down nanoproteomics can provide high-resolution proteoform-resolved molecular fingerprints of diverse cTnI proteoforms to establish proteoform-pathophysiology relationships. This scalable and reproducible antibody-free strategy can generally enable the proteoform-resolved analysis of low-abundance proteins directly from serum to reveal previously unachievable molecular details.
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Affiliation(s)
- Timothy N Tiambeng
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53719, USA
| | - David S Roberts
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53719, USA
| | - Kyle A Brown
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53719, USA
| | - Yanlong Zhu
- Human Proteomics Program, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, 53719, USA
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI, 53719, USA
| | - Bifan Chen
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53719, USA
| | - Zhijie Wu
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53719, USA
| | - Stanford D Mitchell
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI, 53719, USA
- Molecular and Cellular Pharmacology Training Program, University of Wisconsin-Madison, Madison, WI, 53719, USA
| | | | - Song Jin
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53719, USA.
| | - Ying Ge
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53719, USA.
- Human Proteomics Program, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, 53719, USA.
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI, 53719, USA.
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8
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Chen B, Lin Z, Zhu Y, Jin Y, Larson E, Xu Q, Fu C, Zhang Z, Zhang Q, Pritts WA, Ge Y. Middle-Down Multi-Attribute Analysis of Antibody-Drug Conjugates with Electron Transfer Dissociation. Anal Chem 2019; 91:11661-11669. [PMID: 31442030 DOI: 10.1021/acs.analchem.9b02194] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Antibody-drug conjugates (ADCs) are designed to combine the target specificity of monoclonal antibodies and potent cytotoxin drugs to achieve better therapeutic outcomes. Comprehensive evaluation of the quality attributes of ADCs is critical for drug development but remains challenging due to heterogeneity of the construct. Currently, peptide mapping with reversed-phase liquid chromatography (RPLC) coupled to mass spectrometry (MS) is the predominant approach to characterize ADCs. However, it is suboptimal for sequence characterization and quantification of ADCs because it lacks a comprehensive view of coexisting variants and suffers from varying ionization effects of drug-conjugated peptides compared to unconjugated counterparts. Here, we present the first middle-down RPLC-MS analysis of both cysteine (Adcetris; BV) and lysine (Kadcyla; T-DM1) conjugated ADCs at the subunit level (∼25 kDa) with electron transfer dissociation (ETD). We successfully achieved high-resolution separation of subunit isomers arising from different drug conjugation and subsequently localized the conjugation sites. Moreover, we obtained a comprehensive overview of the microvariants associated with each subunits and characterized them such as oxidized variants with different sites. Furthermore, we observed relatively high levels of conjugation near complementarity-determining regions (CDRs) from the heavy chain but no drug conjugation near CDRs of light chain (Lc) from lysine conjugated T-DM1. Based on the extracted ion chromatograms, we accurately measured average drug to antibody ratio (DAR) values and relative occupancy of drug-conjugated subunits. Overall, the middle-down MS approach enables the evaluation of multiple quality attributes including DAR, positional isomers, conjugation sites, occupancy, and microvariants, which potentially opens up a new avenue to characterize ADCs.
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Affiliation(s)
- Bifan Chen
- Department of Chemistry , University of Wisconsin-Madison , Madison , Wisconsin 53706 , United States
| | - Ziqing Lin
- Department of Cell and Regenerative Biology , University of Wisconsin-Madison , Madison , Wisconsin 53706 , United States.,Human Proteomics Program, School of Medicine and Public Health , University of Wisconsin-Madison , Madison , Wisconsin 53706 , United States
| | - Yanlong Zhu
- Department of Cell and Regenerative Biology , University of Wisconsin-Madison , Madison , Wisconsin 53706 , United States.,Human Proteomics Program, School of Medicine and Public Health , University of Wisconsin-Madison , Madison , Wisconsin 53706 , United States
| | - Yutong Jin
- Department of Chemistry , University of Wisconsin-Madison , Madison , Wisconsin 53706 , United States
| | - Eli Larson
- Department of Chemistry , University of Wisconsin-Madison , Madison , Wisconsin 53706 , United States
| | - Qingge Xu
- Department of Cell and Regenerative Biology , University of Wisconsin-Madison , Madison , Wisconsin 53706 , United States.,Human Proteomics Program, School of Medicine and Public Health , University of Wisconsin-Madison , Madison , Wisconsin 53706 , United States
| | - Cexiong Fu
- Process Analytical , AbbVie Inc. , North Chicago , Illinois 60064 , United States
| | - Zhaorui Zhang
- Process Analytical , AbbVie Inc. , North Chicago , Illinois 60064 , United States
| | - Qunying Zhang
- Process Analytical , AbbVie Inc. , North Chicago , Illinois 60064 , United States
| | - Wayne A Pritts
- Process Analytical , AbbVie Inc. , North Chicago , Illinois 60064 , United States
| | - Ying Ge
- Department of Chemistry , University of Wisconsin-Madison , Madison , Wisconsin 53706 , United States.,Department of Cell and Regenerative Biology , University of Wisconsin-Madison , Madison , Wisconsin 53706 , United States.,Human Proteomics Program, School of Medicine and Public Health , University of Wisconsin-Madison , Madison , Wisconsin 53706 , United States
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9
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Abstract
The cardiac troponin complex, composed of three regulatory proteins (cTnI, cTnT, TnC), functions as the critical regulator of cardiac muscle contraction and relaxation. Myofilament protein-protein interactions are regulated by post-translational modifications (PTMs) to the protein constituents of this complex. Dysregulation of troponin PTMs, particularly phosphorylation, results in altered cardiac contractility. Altered PTMs and isoforms have been increasingly recognized as the molecular mechanisms underlying heart diseases. Therefore, it is essential to comprehensively analyze cardiac troponin proteoforms that arise from PTMs, alternative splicing, and sequence variations. In this chapter, we described two detailed protocols for the enrichment and purification of endogenous cardiac troponin proteoforms from cardiac tissue. Subsequently, mass spectrometry (MS)-based top-down proteomics utilizing online liquid chromatography (LC)/quadrupole time-of-flight (Q-TOF) MS for separation, profiling, and quantification of the troponins was demonstrated. Characterization of troponin amino acid sequence and the localization of PTMs were shown using Fourier-transform ion cyclotron resonance (FT-ICR) MS with electron capture dissociation (ECD) and collisionally activated dissociation (CAD). Furthermore, we described the use of MASH software, a comprehensive and free software package developed in our lab, for top-down proteomics data analysis. The methods we described can be applied for the analysis of troponin proteoforms in cardiac tissues, from animal models to human clinical samples, for heart disease.
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10
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Chen J, Shiyanov P, Green KB. Top-down mass spectrometry of intact phosphorylated β-casein: Correlation between the precursor charge state and internal fragments. JOURNAL OF MASS SPECTROMETRY : JMS 2019; 54:527-539. [PMID: 30997701 PMCID: PMC6779312 DOI: 10.1002/jms.4364] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 03/25/2019] [Accepted: 04/11/2019] [Indexed: 05/12/2023]
Abstract
Phosphorylated proteins play essential roles in many cellular processes, and identification and characterization of the relevant phosphoproteins can help to understand underlying mechanisms. Herein, we report a collision-induced dissociation top-down approach for characterizing phosphoproteins on a quadrupole time-of-flight mass spectrometer. β-casein, a protein with two major isoforms and five phosphorylatable serine residues, was used as a model. Peaks corresponding to intact β-casein ions with charged states up to 36+ were detected. Tandem mass spectrometry was performed on β-casein ions of different charge states (12+ , and 15+ to 28+ ) in order to determine the effects of charge state on dissociation of this protein. Most of the abundant fragments corresponded to y, b ions, and internal fragments caused by cleavage of the N-terminal amide bond adjacent to proline residues (Xxx-Pro). The abundance of internal fragments increased with the charge state of the protein precursor ion; these internal fragments predominantly arose from one or two Xxx-Pro cleavage events and were difficult to accurately assign. The presence of abundant sodium adducts of β-casein further complicated the spectra. Our results suggest that when interpreting top-down mass spectra of phosphoproteins and other proteins, researchers should consider the potential formation of internal fragments and sodium adducts for reliable characterization.
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Affiliation(s)
- Jianzhong Chen
- Department of Optometry and Vision Science; University of Alabama at Birmingham; Birmingham, AL, 35294
- Applied Biotechnology Branch; Air Force Research Laboratory; Dayton, OH 45433, USA
- Mass Spectrometry and Proteomics Facility; The Ohio State University; Columbus, OH 43210, USA
- Corresponding author: Jianzhong Chen, Ph.D., Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL, USA; ; Phone: 205.934.8230
| | - Pavel Shiyanov
- Applied Biotechnology Branch; Air Force Research Laboratory; Dayton, OH 45433, USA
| | - Kari B Green
- Mass Spectrometry and Proteomics Facility; The Ohio State University; Columbus, OH 43210, USA
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11
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Affiliation(s)
- Clement
M. Potel
- Biomolecular
Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular
Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584
CH Utrecht, The Netherlands
- Netherlands
Proteomics Centre, Padualaan
8, 3584 CH Utrecht, The Netherlands
| | - Simone Lemeer
- Biomolecular
Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular
Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584
CH Utrecht, The Netherlands
- Netherlands
Proteomics Centre, Padualaan
8, 3584 CH Utrecht, The Netherlands
| | - Albert J. R. Heck
- Biomolecular
Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular
Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584
CH Utrecht, The Netherlands
- Netherlands
Proteomics Centre, Padualaan
8, 3584 CH Utrecht, The Netherlands
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12
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Lermyte F, Valkenborg D, Loo JA, Sobott F. Radical solutions: Principles and application of electron-based dissociation in mass spectrometry-based analysis of protein structure. MASS SPECTROMETRY REVIEWS 2018; 37:750-771. [PMID: 29425406 PMCID: PMC6131092 DOI: 10.1002/mas.21560] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Revised: 01/19/2018] [Accepted: 01/19/2018] [Indexed: 05/11/2023]
Abstract
In recent years, electron capture (ECD) and electron transfer dissociation (ETD) have emerged as two of the most useful methods in mass spectrometry-based protein analysis, evidenced by a considerable and growing body of literature. In large part, the interest in these methods is due to their ability to induce backbone fragmentation with very little disruption of noncovalent interactions which allows inference of information regarding higher order structure from the observed fragmentation behavior. Here, we review the evolution of electron-based dissociation methods, and pay particular attention to their application in "native" mass spectrometry, their mechanism, determinants of fragmentation behavior, and recent developments in available instrumentation. Although we focus on the two most widely used methods-ECD and ETD-we also discuss the use of other ion/electron, ion/ion, and ion/neutral fragmentation methods, useful for interrogation of a range of classes of biomolecules in positive- and negative-ion mode, and speculate about how this exciting field might evolve in the coming years.
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Affiliation(s)
- Frederik Lermyte
- Biomolecular and Analytical Mass Spectrometry Group, Department of Chemistry, University of Antwerp, Antwerp, Belgium
- Centre for Proteomics, University of Antwerp, Antwerp, Belgium
- School of Engineering, University of Warwick, Coventry, United Kingdom
| | - Dirk Valkenborg
- Centre for Proteomics, University of Antwerp, Antwerp, Belgium
- Interuniversity Institute for Biostatistics and Statistical Bioinformatics, Hasselt University, Agoralaan, Diepenbeek, Belgium
- Applied Bio and Molecular Systems, Flemish Institute for Technological Research (VITO), Mol, Belgium
| | - Joseph A Loo
- Department of Biological Chemistry, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, California
- UCLA/DOE Institute for Genomics and Proteomics, University of California-Los Angeles, Los Angeles, California
- Department of Chemistry and Biochemistry, University of California-Los Angeles, Los Angeles, California
| | - Frank Sobott
- Biomolecular and Analytical Mass Spectrometry Group, Department of Chemistry, University of Antwerp, Antwerp, Belgium
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
- School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
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13
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Lin Z, Guo F, Gregorich ZR, Sun R, Zhang H, Hu Y, Shanmuganayagam D, Ge Y. Comprehensive Characterization of Swine Cardiac Troponin T Proteoforms by Top-Down Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2018; 29:1284-1294. [PMID: 29633223 PMCID: PMC6109964 DOI: 10.1007/s13361-018-1925-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 02/14/2018] [Accepted: 02/14/2018] [Indexed: 05/12/2023]
Abstract
Cardiac troponin T (cTnT) regulates the Ca2+-mediated interaction between myosin thick filaments and actin thin filaments during cardiac contraction and relaxation. cTnT is released into the blood following injury, and increased serum levels of the protein are used clinically as a biomarker for myocardial infarction. Moreover, mutations in cTnT are causative in a number of familial cardiomyopathies. With the increasing use of large animal (swine) model to recapitulate human diseases, it is essential to characterize species-dependent protein sequence variants, alternative RNA splicing, and post-translational modifications (PTMs), but challenges remain due to the incomplete database and lack of validation of the predicted splicing isoforms. Herein, we integrated top-down mass spectrometry (MS) with online liquid chromatography (LC) and immunoaffinity purification to comprehensively characterize miniature swine cTnT proteoforms, including those arising from alternative RNA splicing and PTMs. A total of seven alternative splicing isoforms of cTnT were identified by LC/MS from swine left ventricular tissue, with each isoform containing un-phosphorylated and mono-phosphorylated proteoforms. The phosphorylation site was localized to Ser1 for the mono-phosphorylated proteoforms of cTnT1, 3, 4, and 6 by online MS/MS combining collisionally activated dissociation (CAD) and electron transfer dissociation (ETD). Offline MS/MS on Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometer with CAD and electron capture dissociation (ECD) was then utilized to achieve deep sequencing of mono-phosphorylated cTnT1 (35.2 kDa) with a high sequence coverage of 87%. Taken together, this study demonstrated the unique advantage of top-down MS in the comprehensive characterization of protein alternative splicing isoforms together with PTMs. Graphical Abstract ᅟ.
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Affiliation(s)
- Ziqing Lin
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI, 53705, USA
- Human Proteomics Program, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - Fang Guo
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI, 53705, USA
- Department of Cardiology, Shandong Provincial Hospital, Jinan, 250021, Shandong, People's Republic of China
| | - Zachery R Gregorich
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - Ruixiang Sun
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI, 53705, USA
- Institute of Computing Technology, Chinese Academy of Sciences, Beijing, 100190, People's Republic of China
| | - Han Zhang
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Yang Hu
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | | | - Ying Ge
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI, 53705, USA.
- Human Proteomics Program, University of Wisconsin-Madison, Madison, WI, 53705, USA.
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA.
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14
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Soetkamp D, Raedschelders K, Mastali M, Sobhani K, Bairey Merz CN, Van Eyk J. The continuing evolution of cardiac troponin I biomarker analysis: from protein to proteoform. Expert Rev Proteomics 2017; 14:973-986. [PMID: 28984473 DOI: 10.1080/14789450.2017.1387054] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
INTRODUCTION The troponin complex consists of three proteins that fundamentally couple excitation with contraction. Circulating cardiac-specific Troponin I (cTnI) serves as diagnostic biomarker tools for risk stratification of acute coronary syndromes and acute myocardial infarction (MI). Within the heart, cTnI oscillates between inactive and active conformations to either block or disinhibit actinomyosin formation. This molecular mechanism is fine-tuned through extensive protein modifications whose profiles are maladaptively altered with co-morbidities including hypertrophic cardiomyopathy, diabetes, and heart failure. Technological advances in analytical platforms over the last decade enable routine baseline cTnI analysis in patients without cardiovascular complications, and hold potential to expand cTnI readouts that include modified cTnI proteoforms. Areas covered: This review covers the current state, advances, and prospects of analytical platforms that now enable routine baseline cTnI analysis in patients. In parallel, improved mass spectrometry instrumentation and workflows already reveal an array of modified cTnI proteoforms with promising diagnostic implications. Expert commentary: New analytical capabilities provide clinicians and researchers with an opportunity to address important questions surrounding circulating cTnI in the improved diagnosis of specific patient cohorts. These techniques also hold considerable promise for new predictive and prescriptive applications for individualized profiling and improve patient care.
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Affiliation(s)
- Daniel Soetkamp
- a Heart Institute , Cedars-Sinai Medical Center , Los Angeles , CA , USA
| | - Koen Raedschelders
- a Heart Institute , Cedars-Sinai Medical Center , Los Angeles , CA , USA
| | - Mitra Mastali
- a Heart Institute , Cedars-Sinai Medical Center , Los Angeles , CA , USA
| | - Kimia Sobhani
- b Pathology and Laboratory Medicine , Cedars-Sinai Medical Center , Los Angeles , CA , USA
| | - C Noel Bairey Merz
- c Women's Heart Center , Cedars-Sinai Medical Center , Los Angeles , CA , USA
| | - Jennifer Van Eyk
- a Heart Institute , Cedars-Sinai Medical Center , Los Angeles , CA , USA
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15
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Glasner H, Riml C, Micura R, Breuker K. Label-free, direct localization and relative quantitation of the RNA nucleobase methylations m6A, m5C, m3U, and m5U by top-down mass spectrometry. Nucleic Acids Res 2017; 45:8014-8025. [PMID: 28549193 PMCID: PMC5570050 DOI: 10.1093/nar/gkx470] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Accepted: 05/23/2017] [Indexed: 01/28/2023] Open
Abstract
Nucleobase methylations are ubiquitous posttranscriptional modifications of ribonucleic acids (RNA) that can substantially increase the structural diversity of RNA in a highly dynamic fashion with implications for gene expression and human disease. However, high throughput, deep sequencing does not generally provide information on posttranscriptional modifications (PTMs). A promising alternative approach for the characterization of PTMs, i.e. their identification, localization, and relative quantitation, is top-down mass spectrometry (MS). In this study, we have investigated how specific nucleobase methylations affect RNA ionization in electrospray ionization (ESI), and backbone cleavage in collisionally activated dissociation (CAD) and electron detachment dissociation (EDD). For this purpose, we have developed two new approaches for the characterization of RNA methylations in mixtures of either isomers of RNA or nonisomeric RNA forms. Fragment ions from dissociation experiments were analyzed to identify the modification type, to localize the modification sites, and to reveal the site-specific, relative extent of modification for each site.
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Affiliation(s)
- Heidelinde Glasner
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Christian Riml
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Ronald Micura
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Kathrin Breuker
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
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16
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Chen B, Guo X, Tucholski T, Lin Z, McIlwain S, Ge Y. The Impact of Phosphorylation on Electron Capture Dissociation of Proteins: A Top-Down Perspective. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2017; 28:1805-1814. [PMID: 28685494 PMCID: PMC5711594 DOI: 10.1007/s13361-017-1710-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Revised: 05/04/2017] [Accepted: 05/07/2017] [Indexed: 05/12/2023]
Abstract
Electron capture dissociation (ECD) is well suited for the characterization of phosphoproteins, with which labile phosphate groups are generally preserved during the fragmentation process. However, the impact of phosphorylation on ECD fragmentation of intact proteins remains unclear. Here, we have performed a systematic investigation of the phosphorylation effect on ECD of intact proteins by comparing the ECD cleavages of mono-phosphorylated α-casein, multi-phosphorylated β-casein, and immunoaffinity-purified phosphorylated cardiac troponin I with those of their unphosphorylated counterparts, respectively. In contrast to phosphopeptides, phosphorylation has significantly reduced deleterious effects on the fragmentation of intact proteins during ECD. On a global scale, the fragmentation patterns are highly comparable between unphosphorylated and phosphorylated precursors under the same ECD conditions, despite a slight decrease in the number of fragment ions observed for the phosphorylated forms. On a local scale, single phosphorylation of intact proteins imposes minimal effects on fragmentation near the phosphorylation sites, but multiple phosphorylations in close proximity result in a significant reduction of ECD bond cleavages. Graphical Abstract ᅟ.
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Affiliation(s)
- Bifan Chen
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Xiao Guo
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Trisha Tucholski
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Ziqing Lin
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Sean McIlwain
- Department of Biostatistics and Medical Informatics, University of Wisconsin-Madison, Madison, WI, USA
- UW Carbone Cancer Center, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Ying Ge
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, USA.
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA.
- Human Proteomics Program, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA.
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17
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Riley NM, Hebert AS, Dürnberger G, Stanek F, Mechtler K, Westphall MS, Coon JJ. Phosphoproteomics with Activated Ion Electron Transfer Dissociation. Anal Chem 2017; 89:6367-6376. [PMID: 28383256 PMCID: PMC5555596 DOI: 10.1021/acs.analchem.7b00212] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The ability to localize phosphosites to specific amino acid residues is crucial to translating phosphoproteomic data into biological meaningful contexts. In a companion manuscript ( Anal. Chem. 2017 , DOI: 10.1021/acs.analchem.7b00213 ), we described a new implementation of activated ion electron transfer dissociation (AI-ETD) on a quadrupole-Orbitrap-linear ion trap hybrid MS system (Orbitrap Fusion Lumos), which greatly improved peptide fragmentation and identification over ETD and other supplemental activation methods. Here we present the performance of AI-ETD for identifying and localizing sites of phosphorylation in both phosphopeptides and intact phosphoproteins. Using 90 min analyses we show that AI-ETD can identify 24,503 localized phosphopeptide spectral matches enriched from mouse brain lysates, which more than triples identifications from standard ETD experiments and outperforms ETcaD and EThcD as well. AI-ETD achieves these gains through improved quality of fragmentation and MS/MS success rates for all precursor charge states, especially for doubly protonated species. We also evaluate the degree to which phosphate neutral loss occurs from phosphopeptide product ions due to the infrared photoactivation of AI-ETD and show that modifying phosphoRS (a phosphosite localization algorithm) to include phosphate neutral losses can significantly improve localization in AI-ETD spectra. Finally, we demonstrate the utility of AI-ETD in localizing phosphosites in α-casein, an ∼23.5 kDa phosphoprotein that showed eight of nine known phosphorylation sites occupied upon intact mass analysis. AI-ETD provided the greatest sequence coverage for all five charge states investigated and was the only fragmentation method to localize all eight phosphosites for each precursor. Overall, this work highlights the analytical value AI-ETD can bring to both bottom-up and top-down phosphoproteomics.
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Affiliation(s)
- Nicholas M. Riley
- Genome Center of Wisconsin, University of Wisconsin-Madison, Madison, WI, 53706, USA
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Alexander S. Hebert
- Genome Center of Wisconsin, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Gerhard Dürnberger
- Institute of Molecular Pathology (IMP), Campus-Vienna-Biocenter 1, A-1030 Vienna, Austria
- GMI, Gregor Mendel Institute of Molecular Plant Biology, Dr. Bohr Gasse 3, A-1030 Vienna, Austria
- IMBA, Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Dr. Bohr Gasse 3, A-1030 Vienna, Austria
| | - Florian Stanek
- Institute of Molecular Pathology (IMP), Campus-Vienna-Biocenter 1, A-1030 Vienna, Austria
| | - Karl Mechtler
- Institute of Molecular Pathology (IMP), Campus-Vienna-Biocenter 1, A-1030 Vienna, Austria
- IMBA, Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Dr. Bohr Gasse 3, A-1030 Vienna, Austria
| | - Michael S. Westphall
- Genome Center of Wisconsin, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Joshua J. Coon
- Genome Center of Wisconsin, University of Wisconsin-Madison, Madison, WI, 53706, USA
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
- Morgridge Institute for Research, Madison, Wisconsin, USA
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18
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Na I, Kong MJ, Straight S, Pinto JR, Uversky VN. Troponins, intrinsic disorder, and cardiomyopathy. Biol Chem 2017; 397:731-51. [PMID: 27074551 DOI: 10.1515/hsz-2015-0303] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 04/05/2016] [Indexed: 11/15/2022]
Abstract
Cardiac troponin is a dynamic complex of troponin C, troponin I, and troponin T (TnC, TnI, and TnT, respectively) found in the myocyte thin filament where it plays an essential role in cardiac muscle contraction. Mutations in troponin subunits are found in inherited cardiomyopathies, such as hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM). The highly dynamic nature of human cardiac troponin and presence of numerous flexible linkers in its subunits suggest that understanding of structural and functional properties of this important complex can benefit from the consideration of the protein intrinsic disorder phenomenon. We show here that mutations causing decrease in the disorder score in TnI and TnT are significantly more abundant in HCM and DCM than mutations leading to the increase in the disorder score. Identification and annotation of intrinsically disordered regions in each of the troponin subunits conducted in this study can help in better understanding of the roles of intrinsic disorder in regulation of interactomes and posttranslational modifications of these proteins. These observations suggest that disease-causing mutations leading to a decrease in the local flexibility of troponins can trigger a whole plethora of functional changes in the heart.
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19
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Chen B, Hwang L, Ochowicz W, Lin Z, Guardado-Alvarez TM, Cai W, Xiu L, Dani K, Colah C, Jin S, Ge Y. Coupling functionalized cobalt ferrite nanoparticle enrichment with online LC/MS/MS for top-down phosphoproteomics. Chem Sci 2017; 8:4306-4311. [PMID: 28660060 PMCID: PMC5472028 DOI: 10.1039/c6sc05435h] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 03/30/2017] [Indexed: 01/02/2023] Open
Abstract
An integrated top-down phosphoproteomics strategy enabled by functionalized cobalt ferrite nanoparticle enrichment and online LC/MS/MS for identification, quantification, and characterization of low abundance phosphoproteins is presented.
Phosphorylation plays pivotal roles in cellular processes and dysregulated phosphorylation is considered as an underlying mechanism in many human diseases. Top-down mass spectrometry (MS) analyzes intact proteins and provides a comprehensive analysis of protein phosphorylation. However, top-down MS-based phosphoproteomics is challenging due to the difficulty in enriching low abundance intact phosphoproteins as well as separating and detecting the enriched phosphoproteins from complex mixtures. Herein, we have designed and synthesized the next generation functionalized superparamagnetic cobalt ferrite (CoFe2O4) nanoparticles (NPs), and have further developed a top-down phosphoproteomics strategy coupling phosphoprotein enrichment enabled by the functionalized CoFe2O4 NPs with online liquid chromatography (LC)/MS/MS for comprehensive characterization of phosphoproteins. We have demonstrated the highly specific enrichment of a minimal amount of spike-in β-casein from a complex tissue lysate as well as effective separation and quantification of its phosphorylated genetic variants. More importantly, this integrated top-down phosphoproteomics strategy allows for enrichment, identification, quantification, and comprehensive characterization of low abundance endogenous phosphoproteins from complex tissue extracts on a chromatographic time scale.
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Affiliation(s)
- Bifan Chen
- Department of Chemistry , University of Wisconsin-Madison , Madison , WI , USA .
| | - Leekyoung Hwang
- Department of Chemistry , University of Wisconsin-Madison , Madison , WI , USA .
| | - William Ochowicz
- Department of Chemistry , University of Wisconsin-Madison , Madison , WI , USA .
| | - Ziqing Lin
- Department of Cell and Regenerative Biology , University of Wisconsin-Madison , Madison , WI , USA
| | | | - Wenxuan Cai
- Department of Cell and Regenerative Biology , University of Wisconsin-Madison , Madison , WI , USA
| | - Lichen Xiu
- Department of Chemistry , University of Wisconsin-Madison , Madison , WI , USA .
| | - Kunal Dani
- Department of Chemistry , University of Wisconsin-Madison , Madison , WI , USA .
| | - Cyrus Colah
- Department of Cell and Regenerative Biology , University of Wisconsin-Madison , Madison , WI , USA
| | - Song Jin
- Department of Chemistry , University of Wisconsin-Madison , Madison , WI , USA .
| | - Ying Ge
- Department of Chemistry , University of Wisconsin-Madison , Madison , WI , USA . .,Department of Cell and Regenerative Biology , University of Wisconsin-Madison , Madison , WI , USA.,Human Proteomics Program , School of Medicine and Public Health , University of Wisconsin-Madison , Madison , WI , USA
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20
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Toby TK, Fornelli L, Kelleher NL. Progress in Top-Down Proteomics and the Analysis of Proteoforms. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2016; 9:499-519. [PMID: 27306313 PMCID: PMC5373801 DOI: 10.1146/annurev-anchem-071015-041550] [Citation(s) in RCA: 388] [Impact Index Per Article: 48.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
From a molecular perspective, enactors of function in biology are intact proteins that can be variably modified at the genetic, transcriptional, or post-translational level. Over the past 30 years, mass spectrometry (MS) has become a powerful method for the analysis of proteomes. Prevailing bottom-up proteomics operates at the level of the peptide, leading to issues with protein inference, connectivity, and incomplete sequence/modification information. Top-down proteomics (TDP), alternatively, applies MS at the proteoform level to analyze intact proteins with diverse sources of intramolecular complexity preserved during analysis. Fortunately, advances in prefractionation workflows, MS instrumentation, and dissociation methods for whole-protein ions have helped TDP emerge as an accessible and potentially disruptive modality with increasingly translational value. In this review, we discuss technical and conceptual advances in TDP, along with the growing power of proteoform-resolved measurements in clinical and translational research.
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Affiliation(s)
- Timothy K Toby
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois 60208;
| | - Luca Fornelli
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208
| | - Neil L Kelleher
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois 60208;
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208
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21
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Jin Y, Peng Y, Lin Z, Chen YC, Wei L, Hacker TA, Larsson L, Ge Y. Comprehensive analysis of tropomyosin isoforms in skeletal muscles by top-down proteomics. J Muscle Res Cell Motil 2016; 37:41-52. [PMID: 27090236 PMCID: PMC4955698 DOI: 10.1007/s10974-016-9443-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 04/07/2016] [Indexed: 01/09/2023]
Abstract
Mammalian skeletal muscles are heterogeneous in nature and are capable of performing various functions. Tropomyosin (Tpm) is a major component of the thin filament in skeletal muscles and plays an important role in controlling muscle contraction and relaxation. Tpm is known to consist of multiple isoforms resulting from different encoding genes and alternative splicing, along with post-translational modifications. However, a systematic characterization of Tpm isoforms in skeletal muscles is still lacking. Therefore, we employed top-down mass spectrometry (MS) to identify and characterize Tpm isoforms present in different skeletal muscles from multiple species, including swine, rat, and human. Our study revealed that Tpm1.1 and Tpm2.2 are the two major Tpm isoforms in swine and rat skeletal muscles, whereas Tpm1.1, Tpm2.2, and Tpm3.12 are present in human skeletal muscles. Tandem MS was utilized to identify the sequences of the major Tpm isoforms. Furthermore, quantitative analysis revealed muscle-type specific differences in the abundance of un-modified and modified Tpm isoforms in rat and human skeletal muscles. This study represents the first systematic investigation of Tpm isoforms in skeletal muscles, which not only demonstrates the capabilities of top-down MS for the comprehensive characterization of skeletal myofilament proteins but also provides the basis for further studies on these Tpm isoforms in muscle-related diseases.
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Affiliation(s)
- Yutong Jin
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, WI, 53706, USA
| | - Ying Peng
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA
- Human Proteomics Program, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA
| | - Ziqing Lin
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA
- Human Proteomics Program, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA
| | - Yi-Chen Chen
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, WI, 53706, USA
| | - Liming Wei
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA
- Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, P.R. China
| | - Timothy A Hacker
- Department of Medicine, School of Medicine and Public Health, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA
| | - Lars Larsson
- Department of Physiology and Pharmacology, Department of Clinical Neuroscience, Clinical Neurophysiology Section, Karolinska Institutet, 171 77, Stockholm, Sweden
| | - Ying Ge
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, WI, 53706, USA.
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA.
- Human Proteomics Program, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705, USA.
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22
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Steffen P, Kwiatkowski M, Robertson WD, Zarrine-Afsar A, Deterra D, Richter V, Schlüter H. Protein species as diagnostic markers. J Proteomics 2016; 134:5-18. [DOI: 10.1016/j.jprot.2015.12.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 11/28/2015] [Accepted: 12/09/2015] [Indexed: 02/07/2023]
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23
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Yu D, Peng Y, Ayaz-Guner S, Gregorich ZR, Ge Y. Comprehensive Characterization of AMP-Activated Protein Kinase Catalytic Domain by Top-Down Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2016; 27:220-32. [PMID: 26489410 PMCID: PMC4840101 DOI: 10.1007/s13361-015-1286-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Revised: 09/25/2015] [Accepted: 09/26/2015] [Indexed: 05/12/2023]
Abstract
AMP-activated protein kinase (AMPK) is a serine/threonine protein kinase that is essential in regulating energy metabolism in all eukaryotic cells. It is a heterotrimeric protein complex composed of a catalytic subunit (α) and two regulatory subunits (β and γ). C-terminal truncation of AMPKα at residue 312 yielded a protein that is active upon phosphorylation of Thr172 in the absence of β and γ subunits, which is refered to as the AMPK catalytic domain and commonly used to substitute for the AMPK heterotrimeric complex in in vitro kinase assays. However, a comprehensive characterization of the AMPK catalytic domain is lacking. Herein, we expressed a His-tagged human AMPK catalytic domin (denoted as AMPKΔ) in E. coli, comprehensively characterized AMPKΔ in its basal state and after in vitro phosphorylation using top-down mass spectrometry (MS), and assessed how phosphorylation of AMPKΔ affects its activity. Unexpectedly, we found that bacterially-expressed AMPKΔ was basally phosphorylated and localized the phosphorylation site to the His-tag. We found that AMPKΔ had noticeable basal activity and was capable of phosphorylating itself and its substrates without activating phosphorylation at Thr172. Moreover, our data suggested that Thr172 is the only site phosphorylated by its upstream kinase, liver kinase B1, and that this phosphorylation dramatically increases the kinase activity of AMPKΔ. Importantly, we demonstrated that top-down MS in conjunction with in vitro phosphorylation assay is a powerful approach for monitoring phosphorylation reaction and determining sequential order of phosphorylation events in kinase-substrate systems.
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Affiliation(s)
- Deyang Yu
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
- Molecular and Environmental Toxicology Training Program, University of Wisconsin-Madison, Madison, WI, USA
| | - Ying Peng
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
- Human Proteomics Program, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Serife Ayaz-Guner
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
- Human Proteomics Program, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Zachery R. Gregorich
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
- Molecular and Cellular Pharmacology Training Program, University of Wisconsin-Madison, Madison, WI, USA
| | - Ying Ge
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
- Molecular and Environmental Toxicology Training Program, University of Wisconsin-Madison, Madison, WI, USA
- Molecular and Cellular Pharmacology Training Program, University of Wisconsin-Madison, Madison, WI, USA
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, USA
- Human Proteomics Program, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
- Address reprint requests to: Dr. Ying Ge, 1300 University Ave., SMI 130, Madison, Wisconsin, USA. Tel: 608-263-9212, Fax: 608-265-5512,
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24
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Patrie SM. Top-Down Mass Spectrometry: Proteomics to Proteoforms. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 919:171-200. [PMID: 27975217 DOI: 10.1007/978-3-319-41448-5_8] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
This chapter highlights many of the fundamental concepts and technologies in the field of top-down mass spectrometry (TDMS), and provides numerous examples of contributions that TD is making in biology, biophysics, and clinical investigations. TD workflows include variegated steps that may include non-specific or targeted preparative strategies, orthogonal liquid chromatography techniques, analyte ionization, mass analysis, tandem mass spectrometry (MS/MS) and informatics procedures. This diversity of experimental designs has evolved to manage the large dynamic range of protein expression and diverse physiochemical properties of proteins in proteome investigations, tackle proteoform microheterogeneity, as well as determine structure and composition of gas-phase proteins and protein assemblies.
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Affiliation(s)
- Steven M Patrie
- Computational and Systems Biology & Biomedical Engineering Graduate Programs, University of Texas Southwestern Medical Center, Dallas, TX, USA. .,Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, USA. .,Department of Bioengineering, University of Texas at Dallas, Richardson, TX, USA.
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25
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Chen YC, Ayaz-Guner S, Peng Y, Lane NM, Locher M, Kohmoto T, Larsson L, Moss RL, Ge Y. Effective top-down LC/MS+ method for assessing actin isoforms as a potential cardiac disease marker. Anal Chem 2015; 87:8399-8406. [PMID: 26189812 DOI: 10.1021/acs.analchem.5b01745] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Actin is the major component of the cytoskeleton, playing an essential role in the structure and motility of both muscle and nonmuscle cells. It is highly conserved and encoded by a multigene family. α-Cardiac actin (αCAA) and α-skeletal actin (αSKA), encoded by two different genes, are the primary actin isoforms expressed in striated muscles. The relative expression levels of αSKA and αCAA have been shown to vary between species and under pathological conditions. In particular, an increased αSKA expression is believed to be a programmed response of a diseased heart. Therefore, it is essential to quantify the relative expression of αSKA and αCAA, which remains challenging due to the high degree of sequence similarity between these isoforms (98.9%). Herein, we developed a top-down liquid chromatography/mass spectrometry-based ("LC/MS+") method for the rapid purification and comprehensive analysis of α-actin extracted from muscle tissues. We thoroughly investigated all of the actin isoforms in healthy human cardiac and skeletal muscles. We found that αSKA is the only isoform expressed in skeletal muscle, whereas αCAA and αSKA are coexpressed in cardiac muscle. We then applied our method to quantify the α-actin isoforms in human healthy hearts and failing hearts with dilated cardiomyopathy (DCM). We found that αSKA is augmented in DCM compared with healthy controls, 43.1 ± 0.9% versus 23.7 ± 1.7%, respectively. As demonstrated, top-down LC/MS+ provides an effective and comprehensive method for the purification, quantification, and characterization of α-actin isoforms, enabling assessment of their clinical potential as cardiac disease markers.
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Affiliation(s)
- Yi-Chen Chen
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA.,Department of Chemistry, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Serife Ayaz-Guner
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Ying Peng
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA.,Human Proteomics Program, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Nicole M Lane
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Matthew Locher
- Department of Surgery, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Takushi Kohmoto
- Department of Surgery, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Lars Larsson
- Department of Physiology and Pharmacology, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Richard L Moss
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA.,Human Proteomics Program, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Ying Ge
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA.,Department of Chemistry, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA.,Human Proteomics Program, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA
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26
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Artemenko K, Mi J, Bergquist J. Mass-spectrometry-based characterization of oxidations in proteins. Free Radic Res 2015; 49:477-93. [DOI: 10.3109/10715762.2015.1023795] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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27
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Dissecting human skeletal muscle troponin proteoforms by top-down mass spectrometry. J Muscle Res Cell Motil 2015; 36:169-81. [PMID: 25613324 DOI: 10.1007/s10974-015-9404-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 01/07/2015] [Indexed: 01/26/2023]
Abstract
Skeletal muscles are the most abundant tissues in the human body. They are composed of a heterogeneous collection of muscle fibers that perform various functions. Skeletal muscle troponin (sTn) regulates skeletal muscle contraction and relaxation. sTn consists of 3 subunits, troponin I (TnI), troponin T (TnT), and troponin C (TnC). TnI inhibits the actomyosin Mg(2+)-ATPase, TnC binds Ca(2+), and TnT is the tropomyosin (Tm)-binding subunit. The cardiac and skeletal isoforms of Tn share many similarities but the roles of modifications of Tn in the two muscles may differ. The modifications of cardiac Tn are known to alter muscle contractility and have been well-characterized. However, the modification status of sTn remains unclear. Here, we have employed top-down mass spectrometry (MS) to decipher the modifications of human sTnT and sTnI. We have extensively characterized sTnT and sTnI proteoforms, including alternatively spliced isoforms and post-translationally modified forms, found in human skeletal muscle with high mass accuracy and comprehensive sequence coverage. Moreover, we have localized the phosphorylation site of slow sTnT isoform III to Ser1 by tandem MS with electron capture dissociation. This is the first study to comprehensively characterize human sTn and also the first to identify the basal phosphorylation site for human sTnT by top-down MS.
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28
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Gregorich ZR, Ge Y. Top-down proteomics in health and disease: challenges and opportunities. Proteomics 2014; 14:1195-210. [PMID: 24723472 DOI: 10.1002/pmic.201300432] [Citation(s) in RCA: 147] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Revised: 03/10/2014] [Accepted: 03/24/2014] [Indexed: 01/06/2023]
Abstract
Proteomics is essential for deciphering how molecules interact as a system and for understanding the functions of cellular systems in human disease; however, the unique characteristics of the human proteome, which include a high dynamic range of protein expression and extreme complexity due to a plethora of PTMs and sequence variations, make such analyses challenging. An emerging "top-down" MS-based proteomics approach, which provides a "bird's eye" view of all proteoforms, has unique advantages for the assessment of PTMs and sequence variations. Recently, a number of studies have showcased the potential of top-down proteomics for the unraveling of disease mechanisms and discovery of new biomarkers. Nevertheless, the top-down approach still faces significant challenges in terms of protein solubility, separation, and the detection of large intact proteins, as well as underdeveloped data analysis tools. Consequently, new technological developments are urgently needed to advance the field of top-down proteomics. Herein, we intend to provide an overview of the recent applications of top-down proteomics in biomedical research. Moreover, we will outline the challenges and opportunities facing top-down proteomics strategies aimed at understanding and diagnosing human diseases.
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Affiliation(s)
- Zachery R Gregorich
- Molecular and Cellular Pharmacology Training Program, University of Wisconsin-Madison, Madison, WI, USA; Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
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29
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Wijnker PJM, Murphy AM, Stienen GJM, van der Velden J. Troponin I phosphorylation in human myocardium in health and disease. Neth Heart J 2014; 22:463-9. [PMID: 25200323 PMCID: PMC4188840 DOI: 10.1007/s12471-014-0590-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Cardiac troponin I (cTnI) is well known as a biomarker for the diagnosis of myocardial damage. However, because of its central role in the regulation of contraction and relaxation in heart muscle, cTnI may also be a potential target for the treatment of heart failure. Studies in rodent models of cardiac disease and human heart samples showed altered phosphorylation at various sites on cTnI (i.e. site-specific phosphorylation). This is caused by altered expression and/or activity of kinases and phosphatases during heart failure development. It is not known whether these (transient) alterations in cTnI phosphorylation are beneficial or detrimental. Knowledge of the effects of site-specific cTnI phosphorylation on cardiomyocyte contractility is therefore of utmost importance for the development of new therapeutic strategies in patients with heart failure. In this review we focus on the role of cTnI phosphorylation in the healthy heart upon activation of the beta-adrenergic receptor pathway (as occurs during increased stress and exercise) and as a modulator of the Frank-Starling mechanism. Moreover, we provide an overview of recent studies which aimed to reveal the functional consequences of changes in cTnI phosphorylation in cardiac disease.
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Affiliation(s)
- P J M Wijnker
- Department of Physiology, Institute for Cardiovascular Research, VU University Medical Center, Van der Boechorststraat 7, 1081, BT, Amsterdam, the Netherlands,
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30
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Gianazza E, Tremoli E, Banfi C. The selected reaction monitoring/multiple reaction monitoring-based mass spectrometry approach for the accurate quantitation of proteins: clinical applications in the cardiovascular diseases. Expert Rev Proteomics 2014; 11:771-88. [PMID: 25400095 DOI: 10.1586/14789450.2014.947966] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Selected reaction monitoring, also known as multiple reaction monitoring, is a powerful targeted mass spectrometry approach for a confident quantitation of proteins/peptides in complex biological samples. In recent years, its optimization and application have become pivotal and of great interest in clinical research to derive useful outcomes for patient care. Thus, selected reaction monitoring/multiple reaction monitoring is now used as a highly sensitive and selective method for the evaluation of protein abundances and biomarker verification with potential applications in medical screening. This review describes technical aspects for the development of a robust multiplex assay and discussing its recent applications in cardiovascular proteomics: verification of promising disease candidates to select only the highest quality peptides/proteins for a preclinical validation, as well as quantitation of protein isoforms and post-translational modifications.
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Affiliation(s)
- Erica Gianazza
- Laboratory of Cell Biology and Biochemistry of Atherothrombosis, Unit of Proteomics, Centro Cardiologico Monzino IRCCS, Via Parea 4, 20138 Milan, Italy
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31
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Messer AE, Marston SB. Investigating the role of uncoupling of troponin I phosphorylation from changes in myofibrillar Ca(2+)-sensitivity in the pathogenesis of cardiomyopathy. Front Physiol 2014; 5:315. [PMID: 25202278 PMCID: PMC4142463 DOI: 10.3389/fphys.2014.00315] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 08/02/2014] [Indexed: 12/12/2022] Open
Abstract
Contraction in the mammalian heart is controlled by the intracellular Ca(2+) concentration as it is in all striated muscle, but the heart has an additional signaling system that comes into play to increase heart rate and cardiac output during exercise or stress. β-adrenergic stimulation of heart muscle cells leads to release of cyclic-AMP and the activation of protein kinase A which phosphorylates key proteins in the sarcolemma, sarcoplasmic reticulum and contractile apparatus. Troponin I (TnI) and Myosin Binding Protein C (MyBP-C) are the prime targets in the myofilaments. TnI phosphorylation lowers myofibrillar Ca(2+)-sensitivity and increases the speed of Ca(2+)-dissociation and relaxation (lusitropic effect). Recent studies have shown that this relationship between Ca(2+)-sensitivity and TnI phosphorylation may be unstable. In familial cardiomyopathies, both dilated and hypertrophic (DCM and HCM), a mutation in one of the proteins of the thin filament often results in the loss of the relationship (uncoupling) and blunting of the lusitropic response. For familial dilated cardiomyopathy in thin filament proteins it has been proposed that this uncoupling is causative of the phenotype. Uncoupling has also been found in human heart tissue from patients with hypertrophic obstructive cardiomyopathy as a secondary effect. Recently, it has been found that Ca(2+)-sensitizing drugs can promote uncoupling, whilst one Ca(2+)-desensitizing drug Epigallocatechin 3-Gallate (EGCG) can reverse uncoupling. We will discuss recent findings about the role of uncoupling in the development of cardiomyopathies and the molecular mechanism of the process.
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Affiliation(s)
- Andrew E. Messer
- National Heart & Lung Institute, Imperial College LondonLondon, UK
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32
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Ramirez-Correa GA, Martinez-Ferrando MI, Zhang P, Murphy AM. Targeted proteomics of myofilament phosphorylation and other protein posttranslational modifications. Proteomics Clin Appl 2014; 8:543-53. [DOI: 10.1002/prca.201400034] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Revised: 05/29/2014] [Accepted: 06/24/2014] [Indexed: 12/26/2022]
Affiliation(s)
- Genaro A. Ramirez-Correa
- Department of Pediatrics/Division of Cardiology; Johns Hopkins University School of Medicine; Baltimore MD USA
| | | | - Pingbo Zhang
- The Hopkins Bayview Proteomics Center; Johns Hopkins University School of Medicine; Baltimore MD USA
| | - Anne M. Murphy
- Department of Pediatrics/Division of Cardiology; Johns Hopkins University School of Medicine; Baltimore MD USA
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33
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Ying P, Serife AG, Deyang Y, Ying G. Top-down mass spectrometry of cardiac myofilament proteins in health and disease. Proteomics Clin Appl 2014; 8:554-68. [PMID: 24945106 PMCID: PMC4231170 DOI: 10.1002/prca.201400043] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Revised: 05/21/2014] [Accepted: 06/12/2014] [Indexed: 12/29/2022]
Abstract
Myofilaments are composed of thin and thick filaments that coordinate with each other to regulate muscle contraction and relaxation. PTMs together with genetic variations and alternative splicing of the myofilament proteins play essential roles in regulating cardiac contractility in health and disease. Therefore, a comprehensive characterization of the myofilament proteins in physiological and pathological conditions is essential for better understanding the molecular basis of cardiac function and dysfunction. Due to the vast complexity and dynamic nature of proteins, it is challenging to obtain a holistic view of myofilament protein modifications. In recent years, top-down MS has emerged as a powerful approach to study isoform composition and PTMs of proteins owing to its advantage of complete sequence coverage and its ability to identify PTMs and sequence variants without a priori knowledge. In this review, we will discuss the application of top-down MS to the study of cardiac myofilaments and highlight the insights it provides into the understanding of molecular mechanisms in contractile dysfunction of heart failure. Particularly, recent results of cardiac troponin and tropomyosin modifications will be elaborated. The limitations and perspectives on the use of top-down MS for myofilament protein characterization will also be briefly discussed.
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Affiliation(s)
- Peng Ying
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Ayaz-Guner Serife
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Yu Deyang
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
- Molecular and Environmental Toxicology Program, University of Wisconsin-Madison, Madison, WI, USA
| | - Ge Ying
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, USA
- Human Proteomics Program, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
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34
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Peng Y, Gregorich ZR, Valeja SG, Zhang H, Cai W, Chen YC, Guner H, Chen AJ, Schwahn DJ, Hacker TA, Liu X, Ge Y. Top-down proteomics reveals concerted reductions in myofilament and Z-disc protein phosphorylation after acute myocardial infarction. Mol Cell Proteomics 2014; 13:2752-64. [PMID: 24969035 PMCID: PMC4189000 DOI: 10.1074/mcp.m114.040675] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Heart failure (HF) is a leading cause of morbidity and mortality worldwide and is most often precipitated by myocardial infarction. However, the molecular changes driving cardiac dysfunction immediately after myocardial infarction remain poorly understood. Myofilament proteins, responsible for cardiac contraction and relaxation, play critical roles in signal reception and transduction in HF. Post-translational modifications of myofilament proteins afford a mechanism for the beat-to-beat regulation of cardiac function. Thus it is of paramount importance to gain a comprehensive understanding of post-translational modifications of myofilament proteins involved in regulating early molecular events in the post-infarcted myocardium. We have developed a novel liquid chromatography–mass spectrometry-based top-down proteomics strategy to comprehensively assess the modifications of key cardiac proteins in the myofilament subproteome extracted from a minimal amount of myocardial tissue with high reproducibility and throughput. The entire procedure, including tissue homogenization, myofilament extraction, and on-line LC/MS, takes less than three hours. Notably, enabled by this novel top-down proteomics technology, we discovered a concerted significant reduction in the phosphorylation of three crucial cardiac proteins in acutely infarcted swine myocardium: cardiac troponin I and myosin regulatory light chain of the myofilaments and, unexpectedly, enigma homolog isoform 2 (ENH2) of the Z-disc. Furthermore, top-down MS allowed us to comprehensively sequence these proteins and pinpoint their phosphorylation sites. For the first time, we have characterized the sequence of ENH2 and identified it as a phosphoprotein. ENH2 is localized at the Z-disc, which has been increasingly recognized for its role as a nodal point in cardiac signaling. Thus our proteomics discovery opens up new avenues for the investigation of concerted signaling between myofilament and Z-disc in the early molecular events that contribute to cardiac dysfunction and progression to HF.
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Affiliation(s)
- Ying Peng
- From the ‡Department of Cell and Regenerative Biology, University of Wisconsin-Madison, 1300 University Ave., Madison, Wisconsin 53706
| | - Zachery R Gregorich
- From the ‡Department of Cell and Regenerative Biology, University of Wisconsin-Madison, 1300 University Ave., Madison, Wisconsin 53706; §Molecular Pharmacology Training Program, University of Wisconsin-Madison, 1300 University Ave., Madison, Wisconsin 53706
| | - Santosh G Valeja
- From the ‡Department of Cell and Regenerative Biology, University of Wisconsin-Madison, 1300 University Ave., Madison, Wisconsin 53706
| | - Han Zhang
- From the ‡Department of Cell and Regenerative Biology, University of Wisconsin-Madison, 1300 University Ave., Madison, Wisconsin 53706
| | - Wenxuan Cai
- From the ‡Department of Cell and Regenerative Biology, University of Wisconsin-Madison, 1300 University Ave., Madison, Wisconsin 53706; §Molecular Pharmacology Training Program, University of Wisconsin-Madison, 1300 University Ave., Madison, Wisconsin 53706
| | - Yi-Chen Chen
- ¶Department of Chemistry, University of Wisconsin-Madison, 1300 University Ave., Madison, Wisconsin 53706
| | - Huseyin Guner
- From the ‡Department of Cell and Regenerative Biology, University of Wisconsin-Madison, 1300 University Ave., Madison, Wisconsin 53706; ‖Human Proteomics Program, University of Wisconsin-Madison, 1300 University Ave., Madison, Wisconsin 53706
| | - Albert J Chen
- From the ‡Department of Cell and Regenerative Biology, University of Wisconsin-Madison, 1300 University Ave., Madison, Wisconsin 53706
| | - Denise J Schwahn
- From the ‡Department of Cell and Regenerative Biology, University of Wisconsin-Madison, 1300 University Ave., Madison, Wisconsin 53706
| | - Timothy A Hacker
- ‡‡Department of Medicine, University of Wisconsin-Madison, 1300 University Ave., Madison, Wisconsin 53706
| | - Xiaowen Liu
- §§Department of BioHealth Informatics, Indiana University-Purdue University Indianapolis, 719 Indiana Ave., Indianapolis, Indiana 46202; ¶¶Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, 410 West 10th Street, Indianapolis, Indiana 46202
| | - Ying Ge
- From the ‡Department of Cell and Regenerative Biology, University of Wisconsin-Madison, 1300 University Ave., Madison, Wisconsin 53706; ¶Department of Chemistry, University of Wisconsin-Madison, 1300 University Ave., Madison, Wisconsin 53706; ‖Human Proteomics Program, University of Wisconsin-Madison, 1300 University Ave., Madison, Wisconsin 53706;
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35
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Kooij V, Venkatraman V, Tra J, Kirk JA, Rowell J, Blice-Baum A, Cammarato A, Van Eyk JE. Sizing up models of heart failure: Proteomics from flies to humans. Proteomics Clin Appl 2014; 8:653-64. [PMID: 24723306 PMCID: PMC4282793 DOI: 10.1002/prca.201300123] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Revised: 01/31/2014] [Accepted: 04/03/2014] [Indexed: 12/25/2022]
Abstract
Cardiovascular disease is the leading cause of death in the western world. Heart failure is a heterogeneous and complex syndrome, arising from various etiologies, which result in cellular phenotypes that vary from patient to patient. The ability to utilize genetic manipulation and biochemical experimentation in animal models has made them indispensable in the study of this chronic condition. Similarly, proteomics has been helpful for elucidating complicated cellular and molecular phenotypes and has the potential to identify circulating biomarkers and drug targets for therapeutic intervention. In this review, the use of human samples and animal model systems (pig, dog, rat, mouse, zebrafish, and fruit fly) in cardiac research is discussed. Additionally, the protein sequence homology between these species and the extent of conservation at the level of the phospho-proteome in major kinase signaling cascades involved in heart failure are investigated.
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Affiliation(s)
- Viola Kooij
- Department of Medicine, Division of Cardiology, The Johns Hopkins University, Baltimore, MD, USA
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36
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The art of the deal in myofilament modulation of function. J Mol Cell Cardiol 2014; 72:238-40. [PMID: 24732213 DOI: 10.1016/j.yjmcc.2014.04.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Revised: 04/02/2014] [Accepted: 04/03/2014] [Indexed: 10/25/2022]
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37
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Zhang J, Corbett JR, Plymire DA, Greenberg BM, Patrie SM. Proteoform analysis of lipocalin-type prostaglandinD-synthase from human cerebrospinal fluid by isoelectric focusing and superficially porous liquid chromatography with Fourier transform mass spectrometry. Proteomics 2014; 14:1223-31. [DOI: 10.1002/pmic.201300368] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Revised: 12/31/2013] [Accepted: 02/11/2014] [Indexed: 02/06/2023]
Affiliation(s)
- Junmei Zhang
- Department of Pathology; University of Texas Southwestern Medical Center; TX USA
| | - John R. Corbett
- Department of Bioengineering; University of Texas at Dallas; TX USA
| | - Daniel A. Plymire
- Department of Pathology; University of Texas Southwestern Medical Center; TX USA
| | | | - Steven M. Patrie
- Department of Pathology; University of Texas Southwestern Medical Center; TX USA
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38
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Gregorich ZR, Chang YH, Ge Y. Proteomics in heart failure: top-down or bottom-up? Pflugers Arch 2014; 466:1199-209. [PMID: 24619480 DOI: 10.1007/s00424-014-1471-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Revised: 01/31/2014] [Accepted: 02/04/2014] [Indexed: 01/11/2023]
Abstract
The pathophysiology of heart failure (HF) is diverse, owing to multiple etiologies and aberrations in a number of cellular processes. Therefore, it is essential to understand how defects in the molecular pathways that mediate cellular responses to internal and external stressors function as a system to drive the HF phenotype. Mass spectrometry (MS)-based proteomics strategies have great potential for advancing our understanding of disease mechanisms at the systems level because proteins are the effector molecules for all cell functions and, thus, are directly responsible for determining cell phenotype. Two MS-based proteomics strategies exist: peptide-based bottom-up and protein-based top-down proteomics--each with its own unique strengths and weaknesses for interrogating the proteome. In this review, we will discuss the advantages and disadvantages of bottom-up and top-down MS for protein identification, quantification, and analysis of post-translational modifications, as well as highlight how both of these strategies have contributed to our understanding of the molecular and cellular mechanisms underlying HF. Additionally, the challenges associated with both proteomics approaches will be discussed and insights will be offered regarding the future of MS-based proteomics in HF research.
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Affiliation(s)
- Zachery R Gregorich
- Molecular and Cellular Pharmacology Training Program, University of Wisconsin-Madison, Madison, WI, USA
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39
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Reactive oxygen species and excitation-contraction coupling in the context of cardiac pathology. J Mol Cell Cardiol 2014; 73:92-102. [PMID: 24631768 DOI: 10.1016/j.yjmcc.2014.03.001] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 02/05/2014] [Accepted: 03/01/2014] [Indexed: 01/12/2023]
Abstract
Reactive oxygen species (ROS) are highly reactive oxygen-derived chemical compounds that are by-products of aerobic cellular metabolism as well as crucial second messengers in numerous signaling pathways. In excitation-contraction-coupling (ECC), which links electrical signaling and coordinated cardiac contraction, ROS have a severe impact on several key ion handling proteins such as ion channels and transporters, but also on regulating proteins such as protein kinases (e.g. CaMKII, PKA or PKC), thereby pivotally influencing the delicate balance of this finely tuned system. While essential as second messengers, ROS may be deleterious when excessively produced due to a disturbed balance in Na(+) and Ca(2+) handling, resulting in Na(+) and Ca(2+) overload, SR Ca(2+) loss and contractile dysfunction. This may, in the end, result in systolic and diastolic dysfunction and arrhythmias. This review aims to provide an overview of the single targets of ROS in ECC and to outline the role of ROS in major cardiac pathologies, such as heart failure and arrhythmogenesis. This article is part of a Special Issue entitled "Redox Signalling in the Cardiovascular System"
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40
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Katrukha IA. Human cardiac troponin complex. Structure and functions. BIOCHEMISTRY (MOSCOW) 2014; 78:1447-65. [DOI: 10.1134/s0006297913130063] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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41
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Li G, Yin Y, Huang G. Increased disulfide peptide sequence coverage via “cleavage ON/OFF” switch during nanoelectrospray. RSC Adv 2014. [DOI: 10.1039/c4ra12386g] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Disulfide peptide sequence coverage could be increased via switching “cleavage ON/OFF” modes between conventional and induced nanoelectrospray MS within 1 min.
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Affiliation(s)
- Gongyu Li
- Department of Chemistry
- University of Science and Technology of China
- Hefei, P.R. China
| | - Yue Yin
- Department of Chemistry
- University of Science and Technology of China
- Hefei, P.R. China
| | - Guangming Huang
- Department of Chemistry
- University of Science and Technology of China
- Hefei, P.R. China
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42
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43
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Kirk JA, Zhang P, Murphy AM, Van Eyk JE. Troponin I alterations detected by multiple-reaction monitoring: how might this impact the study of heart failure? Expert Rev Proteomics 2013; 10:5-8. [PMID: 23414352 DOI: 10.1586/epr.12.77] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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44
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In-depth proteomic analysis of human tropomyosin by top-down mass spectrometry. J Muscle Res Cell Motil 2013; 34:199-210. [PMID: 23881156 DOI: 10.1007/s10974-013-9352-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Accepted: 06/27/2013] [Indexed: 01/29/2023]
Abstract
Tropomyosins (Tms) are a family of highly conserved actin-binding proteins that play critical roles in a variety of processes, most notably, in the regulation of muscle contraction and relaxation. It is well known that different Tm isoforms have distinct functions and that altered expression of Tm isoforms could lead to changes in cardiac structure and function. To precisely define Tm isoform expression in the human heart, towards a better understanding of their functional roles, we have employed top-down mass spectrometry for in-depth proteomic characterization of Tm isoforms. Using a minimal amount of human heart tissue from rejected donor organs, we confirmed the presence of multiple Tm isoforms including α-Tm, β-Tm and κ-Tm in the human heart, with α-Tm being the predominant isoform, followed by minor isoforms of β-Tm and κ-Tm. Interestingly, our data revealed regional variations of Tm isoforms and post-translational modifications in the human heart. Specifically, the expression level of κ-Tm was highest in the left atrium but nearly undetectable in the left ventricle. The phosphorylation level of α-Tm (pα-Tm) was significantly higher in the atria than it was in the ventricles. The sequences of all Tm isoforms were characterized and the sites of post-translational modifications were localized. Clearly, top-down mass spectrometry is an attractive method for comprehensive characterization of Tm isoforms and post-translational modifications since it can universally detect and quantify all types of protein modifications without a priori knowledge and without the need for specific antibodies.
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Salameh A, Djilali H, Blanke K, Gonzalez Casanova J, von Salisch S, Savtschenko A, Dhein S, Dähnert I. Cardiac fibroblasts inhibit β-adrenoceptor-dependent connexin43 expression in neonatal rat cardiomyocytes. Naunyn Schmiedebergs Arch Pharmacol 2013; 386:421-33. [PMID: 23455518 DOI: 10.1007/s00210-013-0843-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Accepted: 02/13/2013] [Indexed: 01/19/2023]
Abstract
Cardiac fibroblasts play an important role in adverse cardiac remodelling. As in many cardiac diseases connexin43 (Cx43) is altered, we wanted to elucidate whether fibroblasts may influence cardiac Cx43 expression. We used four different cell culture systems of neonatal rat cardiomyocytes (CM) and fibroblasts (FB): type 1, pure CM culture; type 2, co-culture of CM/FB; type 3, pure FB culture; type 4, Transwell® system: CM/FB co-cultured but separated by a microporous membrane. Stimulation of types 1-3 cell culture models with isoprenaline significantly enhanced Cx43-protein and Cx43-mRNA expression as well as phosphorylation of ERK and translocation of AP1 and CREB only in the CM cultures; whereas, the CM/FB co-cultures and the FB cultures did not respond to isoprenaline. Similarly, if CM and FB were separated by a microporous membrane (Transwell® system) the isoprenaline-induced increase in CM Cx43 was completely suppressed, suggesting the existence of a soluble factor responsible for the suppressant effect of FB. Angiotensin II determination in types 1 and 2 cell culture supernatants revealed that the CM/FB co-cultures exhibited a significant higher angiotensin II release than the CM cultures. Furthermore, we aimed to inhibit angiotensin II signal transduction pathway: blockade of AT1 receptors or PKC inhibition restored the responsiveness of CM/FB co-cultures to isoprenaline. Moreover, external addition of angiotensin II to CM cultures also resulted in suppression of isoprenaline-stimulated Cx43 expression in an AT1-receptor- and PKC-dependent manner. Thus, our study indicates that cardiac fibroblasts inhibit β-adrenoceptor-dependent Cx43 signalling in CM involving angiotensin II.
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Affiliation(s)
- A Salameh
- Clinic for Paediatric Cardiology, University of Leipzig, Heart Centre, Struempellstr. 39, 04289 Leipzig, Germany.
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Peng Y, Chen X, Zhang H, Xu Q, Hacker TA, Ge Y. Top-down targeted proteomics for deep sequencing of tropomyosin isoforms. J Proteome Res 2013; 12:187-98. [PMID: 23256820 PMCID: PMC3596867 DOI: 10.1021/pr301054n] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Tropomyosins (Tm) constitute a family of ubiquitous and highly conserved actin-binding proteins, playing essential roles in a variety of biological processes. Tm isoforms produced by multiple Tm encoding genes and alternatively expressed exons along with post-translational modifications (PTMs) regulate Tm function. Therefore, to gain a better understanding of the functional role of Tm, it is essential to fully characterize Tm isoforms. Herein, we developed a top-down high-resolution mass spectrometry (MS)-based targeted proteomics method for comprehensive characterization of Tm isoforms. α-Tm was identified to be the predominant isoform in swine cardiac muscle. We further characterized its sequence and localized the PTMs such as acetylation and phosphorylation as well as amino acid polymorphisms. Interestingly, we discovered a "novel" Tm isoform that does not match with any of the currently available swine Tm sequences. A deep sequencing of this isoform by top-down MS revealed an exact match with mouse β-Tm sequence, suggesting that this "novel" isoform is swine β-Tm which is 100% conserved between swine and mouse. Taken together, we demonstrated that top-down targeted proteomics provides a powerful tool for deep sequencing of Tm isoforms from genetic variations together with complete mapping of the PTM sites.
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Affiliation(s)
- Ying Peng
- Human Proteomics Program, University of Wisconsin-Madison, Madison, WI, 53706
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI, 53706
| | - Xin Chen
- Human Proteomics Program, University of Wisconsin-Madison, Madison, WI, 53706
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI, 53706
| | - Han Zhang
- Human Proteomics Program, University of Wisconsin-Madison, Madison, WI, 53706
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706
| | - Qingge Xu
- Human Proteomics Program, University of Wisconsin-Madison, Madison, WI, 53706
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI, 53706
| | - Timothy A. Hacker
- Department of Medicine, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, 53706
| | - Ying Ge
- Human Proteomics Program, University of Wisconsin-Madison, Madison, WI, 53706
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI, 53706
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706
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Boehm ME, Seidler J, Hahn B, Lehmann WD. Site-specific degree of phosphorylation in proteins measured by liquid chromatography-electrospray mass spectrometry. Proteomics 2012; 12:2167-78. [PMID: 22653803 DOI: 10.1002/pmic.201100561] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
This review focuses on quantitative protein phosphorylation analysis based on coverage of both the phosphorylated and nonphosphorylated forms. In this way, site-specific data on the degree of phosphorylation can be measured, generating the most detailed level of phosphorylation status analysis of proteins. To highlight the experimental challenges in this type of quantitative protein phosphorylation analysis, we discuss the typical workflows for mass spectrometry-based proteomics with a focus on the quantitative analysis of peptide/phosphopeptide ratios. We review workflows for measuring site-specific degrees of phosphorylation including the label-free approach, differential stable isotope labeling of analytes, and methods based on the addition of stable isotope labeled peptide/phosphopeptide pairs as internal standards. The discussion also includes the determination of phosphopeptide isoform abundance data for multiply phosphorylated motifs that contain information about the connectivity of phosphorylation events. The review closes with a prospective on the use of intact stable isotope labeled proteins as internal standards and a summarizing discussion of the typical accuracies of the individual methods.
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Affiliation(s)
- Martin E Boehm
- Molecular Structure Analysis, German Cancer Research Center (DKFZ), Heidelberg, Germany
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Wijnker PJM, Foster DB, Tsao AL, Frazier AH, dos Remedios CG, Murphy AM, Stienen GJM, van der Velden J. Impact of site-specific phosphorylation of protein kinase A sites Ser23 and Ser24 of cardiac troponin I in human cardiomyocytes. Am J Physiol Heart Circ Physiol 2012; 304:H260-8. [PMID: 23144315 DOI: 10.1152/ajpheart.00498.2012] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
PKA-mediated phosphorylation of contractile proteins upon β-adrenergic stimulation plays an important role in the regulation of cardiac performance. Phosphorylation of the PKA sites (Ser(23)/Ser(24)) of cardiac troponin (cTn)I results in a decrease in myofilament Ca(2+) sensitivity and an increase in the rate of relaxation. However, the relation between the level of phosphorylation of the sites and the functional effects in the human myocardium is unknown. Therefore, site-directed mutagenesis was used to study the effects of phosphorylation at Ser(23) and Ser(24) of cTnI on myofilament function in human cardiac tissue. Serines were replaced by aspartic acid (D) or alanine (A) to mimic phosphorylation and dephosphorylation, respectively. cTnI-DD mimics both sites phosphorylated, cTnI-AD mimics Ser(23) unphosphorylated and Ser(24) phosphorylated, cTnI-DA mimics Ser(23) phosphorylated and Ser(24) unphosphorylated, and cTnI-AA mimics both sites unphosphorylated. Force development was measured at various Ca(2+) concentrations in permeabilized cardiomyocytes in which the endogenous troponin complex was exchanged with these recombinant human troponin complexes. In donor cardiomyocytes, myofilament Ca(2+) sensitivity (pCa(50)) was significantly lower in cTnI-DD (pCa(50): 5.39 ± 0.01) compared with cTnI-AA (pCa(50): 5.50 ± 0.01), cTnI-AD (pCa(50): 5.48 ± 0.01), and cTnI-DA (pCa(50): 5.51 ± 0.01) at ~70% cTn exchange. No effects were observed on the rate of tension redevelopment. In cardiomyocytes from idiopathic dilated cardiomyopathic tissue, a linear decline in pCa(50) with cTnI-DD content was observed, saturating at ~55% bisphosphorylation. Our data suggest that in the human myocardium, phosphorylation of both PKA sites on cTnI is required to reduce myofilament Ca(2+) sensitivity, which is maximal at ~55% bisphosphorylated cTnI. The implications for in vivo cardiac function in health and disease are detailed in the DISCUSSION in this article.
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Affiliation(s)
- Paul J M Wijnker
- Laboratory for Physiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands.
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Guy MJ, Chen YC, Clinton L, Zhang H, Zhang J, Dong X, Xu Q, Ayaz-Guner S, Ge Y. The impact of antibody selection on the detection of cardiac troponin I. Clin Chim Acta 2012; 420:82-8. [PMID: 23107929 DOI: 10.1016/j.cca.2012.10.034] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Accepted: 10/17/2012] [Indexed: 11/28/2022]
Abstract
BACKGROUND Cardiac troponin I (cTnI) is the current standard biomarker for diagnosing acute myocardial infarction and for risk-stratification of acute coronary syndromes in patients. However, it remains unclear how the epitope specificity of antibodies in immunoassays influences the detection of various modified forms of cTnI. METHODS Four mouse anti-human cTnI monoclonal antibodies targeting different regions of human cTnI were chosen for immunoaffinity purification of cTnI from human and swine cardiac tissue. High-resolution intact protein mass spectrometry was employed to assess the comparative performance of these four antibodies in detecting modified forms of cTnI. RESULTS Our data revealed that antibody selection significantly impacts the relative protein yield of cTn from immunoaffinity purification. Remarkably, a single amino acid variation in cTnI (G->S) in the epitope region completely abolished the binding between monoclonal antibody 560 and swine cTnI in solution. Moreover, proteolytic degradation around the epitope region severely compromised the detection of proteolytic fragment forms of cTnI by monoclonal antibodies. In contrast, the phosphorylation status near the epitope region did not significantly affect the antibody recognition of cTnI. CONCLUSION Caution needs to be taken in the interpretation of the data produced by immuno-assays with monoclonal antibodies against various epitopes of cTnI.
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Affiliation(s)
- Moltu J Guy
- Human Proteomics Program, School of Medicine and Public Health, University of Wisconsin, Madison, WI 53706, United States
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Cordwell SJ, White MY. Targeted Proteomics for Determining Phosphorylation Site-Specific Associations in Cardiovascular Disease. Circulation 2012; 126:1803-7. [DOI: 10.1161/circulationaha.112.136507] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Stuart J. Cordwell
- From the School of Molecular Bioscience (S.J.C., M.Y.W.), and Discipline of Pathology, School of Medical Sciences (S.J.C.), The University of Sydney, New South Wales, Australia
| | - Melanie Y. White
- From the School of Molecular Bioscience (S.J.C., M.Y.W.), and Discipline of Pathology, School of Medical Sciences (S.J.C.), The University of Sydney, New South Wales, Australia
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