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Meadow ME, Broas S, Hoare M, Alimohammadi F, Welle KA, Swovick K, Hryhorenko JR, Martinez JC, Biashad SA, Seluanov A, Gorbunova V, Buchwalter A, Ghaemmaghami S. Proteome Birthdating Reveals Age-Selectivity of Protein Ubiquitination. Mol Cell Proteomics 2024; 23:100791. [PMID: 38797438 PMCID: PMC11260378 DOI: 10.1016/j.mcpro.2024.100791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 03/27/2024] [Accepted: 05/15/2024] [Indexed: 05/29/2024] Open
Abstract
Within a cell, proteins have distinct and highly variable half-lives. As a result, the molecular ages of proteins can range from seconds to years. How the age of a protein influences its environmental interactions is a largely unexplored area of biology. To investigate the age-selectivity of cellular pathways, we developed a methodology termed "proteome birthdating" that barcodes proteins based on their time of synthesis. We demonstrate that this approach provides accurate measurements of protein turnover kinetics from a single biological sample encoding multiple labeling time-points. As a first application of the birthdated proteome, we investigated the age distribution of the human ubiquitinome. Our results indicate that the vast majority of ubiquitinated proteins in a cell consist of newly synthesized proteins and that these young proteins constitute the bulk of the degradative flux through the proteasome. Rapidly ubiquitinated nascent proteins are enriched in cytosolic subunits of large protein complexes. Conversely, proteins destined for the secretory pathway and vesicular transport have older ubiquitinated populations. Our data also identify a smaller subset of older ubiquitinated cellular proteins that do not appear to be targeted to the proteasome for rapid degradation. Together, our data provide an age census of the human ubiquitinome and establish proteome birthdating as a robust methodology for investigating the protein age-selectivity of diverse cellular pathways.
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Affiliation(s)
- Michael E Meadow
- Department of Biology, University of Rochester, New York, USA; Medical Scientist Training Program, University of Rochester, New York, USA
| | - Sarah Broas
- Department of Biology, University of Rochester, New York, USA
| | - Margaret Hoare
- Department of Biology, University of Rochester, New York, USA
| | - Fatemeh Alimohammadi
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York, USA
| | - Kevin A Welle
- University of Rochester Mass Spectrometry Resource Laboratory, New York, USA
| | - Kyle Swovick
- University of Rochester Mass Spectrometry Resource Laboratory, New York, USA
| | | | - John C Martinez
- Department of Biology, University of Rochester, New York, USA
| | | | - Andrei Seluanov
- Department of Biology, University of Rochester, New York, USA; Department of Medicine, University of Rochester Medical Center, Rochester, New York, USA
| | - Vera Gorbunova
- Department of Biology, University of Rochester, New York, USA; Department of Medicine, University of Rochester Medical Center, Rochester, New York, USA
| | - Abigail Buchwalter
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, California, USA
| | - Sina Ghaemmaghami
- Department of Biology, University of Rochester, New York, USA; University of Rochester Mass Spectrometry Resource Laboratory, New York, USA.
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Prus G, Satpathy S, Weinert BT, Narita T, Choudhary C. Global, site-resolved analysis of ubiquitylation occupancy and turnover rate reveals systems properties. Cell 2024; 187:2875-2892.e21. [PMID: 38626770 PMCID: PMC11136510 DOI: 10.1016/j.cell.2024.03.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Revised: 12/19/2023] [Accepted: 03/19/2024] [Indexed: 04/18/2024]
Abstract
Ubiquitylation regulates most proteins and biological processes in a eukaryotic cell. However, the site-specific occupancy (stoichiometry) and turnover rate of ubiquitylation have not been quantified. Here we present an integrated picture of the global ubiquitylation site occupancy and half-life. Ubiquitylation site occupancy spans over four orders of magnitude, but the median ubiquitylation site occupancy is three orders of magnitude lower than that of phosphorylation. The occupancy, turnover rate, and regulation of sites by proteasome inhibitors are strongly interrelated, and these attributes distinguish sites involved in proteasomal degradation and cellular signaling. Sites in structured protein regions exhibit longer half-lives and stronger upregulation by proteasome inhibitors than sites in unstructured regions. Importantly, we discovered a surveillance mechanism that rapidly and site-indiscriminately deubiquitylates all ubiquitin-specific E1 and E2 enzymes, protecting them against accumulation of bystander ubiquitylation. The work provides a systems-scale, quantitative view of ubiquitylation properties and reveals general principles of ubiquitylation-dependent governance.
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Affiliation(s)
- Gabriela Prus
- Department of Proteomics, The Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark
| | - Shankha Satpathy
- Department of Proteomics, The Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark
| | - Brian T Weinert
- Department of Proteomics, The Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark
| | - Takeo Narita
- Department of Proteomics, The Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark
| | - Chunaram Choudhary
- Department of Proteomics, The Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark.
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Firnau MB, Plotz G, Zeuzem S, Brieger A. Key role of phosphorylation sites in ATPase domain and Linker region of MLH1 for DNA binding and functionality of MutLα. Sci Rep 2023; 13:12503. [PMID: 37532794 PMCID: PMC10397344 DOI: 10.1038/s41598-023-39750-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Accepted: 07/30/2023] [Indexed: 08/04/2023] Open
Abstract
MutLα is essential for human DNA mismatch repair (MMR). It harbors a latent endonuclease, is responsible for recruitment of process associated proteins and is relevant for strand discrimination. Recently, we demonstrated that the MMR function of MutLα is regulated by phosphorylation of MLH1 at serine (S) 477. In the current study, we focused on S87 located in the ATPase domain of MLH1 and on S446, S456 and S477 located in its linker region. We analysed the phosphorylation-dependent impact of these amino acids on DNA binding, MMR ability and thermal stability of MutLα. We were able to demonstrate that phosphorylation at S87 of MLH1 inhibits DNA binding of MutLα. In addition, we detected that its MMR function seems to be regulated predominantly via phosphorylation of serines in the linker domain, which are also partially involved in the regulation of DNA binding. Furthermore, we found that the thermal stability of MutLα decreased in relation to its phosphorylation status implying that complete phosphorylation might lead to instability and degradation of MLH1. In summary, we showed here, for the first time, a phosphorylation-dependent regulation of DNA binding of MutLα and hypothesized that this might significantly impact its functional regulation during MMR in vivo.
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Affiliation(s)
- May-Britt Firnau
- Goethe University Frankfurt, University Hospital, Medical Clinic 1, Biomedical Research Laboratory, Theodor-Stern-Kai 7, 60590, Frankfurt, Germany
| | - Guido Plotz
- Goethe University Frankfurt, University Hospital, Medical Clinic 1, Biomedical Research Laboratory, Theodor-Stern-Kai 7, 60590, Frankfurt, Germany
| | - Stefan Zeuzem
- Goethe University Frankfurt, University Hospital, Medical Clinic 1, Biomedical Research Laboratory, Theodor-Stern-Kai 7, 60590, Frankfurt, Germany
| | - Angela Brieger
- Goethe University Frankfurt, University Hospital, Medical Clinic 1, Biomedical Research Laboratory, Theodor-Stern-Kai 7, 60590, Frankfurt, Germany.
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Zittlau K, Nashier P, Cavarischia-Rega C, Macek B, Spät P, Nalpas N. Recent progress in quantitative phosphoproteomics. Expert Rev Proteomics 2023; 20:469-482. [PMID: 38116637 DOI: 10.1080/14789450.2023.2295872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 12/12/2023] [Indexed: 12/21/2023]
Abstract
INTRODUCTION Protein phosphorylation is a critical post-translational modification involved in the regulation of numerous cellular processes from signal transduction to modulation of enzyme activities. Knowledge of dynamic changes of phosphorylation levels during biological processes, under various treatments or between healthy and disease models is fundamental for understanding the role of each phosphorylation event. Thereby, LC-MS/MS based technologies in combination with quantitative proteomics strategies evolved as a powerful strategy to investigate the function of individual protein phosphorylation events. AREAS COVERED State-of-the-art labeling techniques including stable isotope and isobaric labeling provide precise and accurate quantification of phosphorylation events. Here, we review the strengths and limitations of recent quantification methods and provide examples based on current studies, how quantitative phosphoproteomics can be further optimized for enhanced analytic depth, dynamic range, site localization, and data integrity. Specifically, reducing the input material demands is key to a broader implementation of quantitative phosphoproteomics, not least for clinical samples. EXPERT OPINION Despite quantitative phosphoproteomics is one of the most thriving fields in the proteomics world, many challenges still have to be overcome to facilitate even deeper and more comprehensive analyses as required in the current research, especially at single cell levels and in clinical diagnostics.
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Affiliation(s)
- Katharina Zittlau
- Quantitative Proteomics, Interfaculty Institute of Cell Biology, University of Tuebingen, Tuebingen , Germany
| | - Payal Nashier
- Quantitative Proteomics, Interfaculty Institute of Cell Biology, University of Tuebingen, Tuebingen , Germany
| | - Claudia Cavarischia-Rega
- Quantitative Proteomics, Interfaculty Institute of Cell Biology, University of Tuebingen, Tuebingen , Germany
| | - Boris Macek
- Quantitative Proteomics, Interfaculty Institute of Cell Biology, University of Tuebingen, Tuebingen , Germany
| | - Philipp Spät
- Quantitative Proteomics, Interfaculty Institute of Cell Biology, University of Tuebingen, Tuebingen , Germany
| | - Nicolas Nalpas
- Quantitative Proteomics, Interfaculty Institute of Cell Biology, University of Tuebingen, Tuebingen , Germany
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Proteomic Insights into Cardiac Fibrosis: From Pathophysiological Mechanisms to Therapeutic Opportunities. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27248784. [PMID: 36557919 PMCID: PMC9781843 DOI: 10.3390/molecules27248784] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 12/08/2022] [Accepted: 12/09/2022] [Indexed: 12/14/2022]
Abstract
Cardiac fibrosis is a common pathophysiologic process in nearly all forms of heart disease which refers to excessive deposition of extracellular matrix proteins by cardiac fibroblasts. Activated fibroblasts are the central cellular effectors in cardiac fibrosis, and fibrotic remodelling can cause several cardiac dysfunctions either by reducing the ejection fraction due to a stiffened myocardial matrix, or by impairing electric conductance. Recently, there is a rising focus on the proteomic studies of cardiac fibrosis for pathogenesis elucidation and potential biomarker mining. This paper summarizes the current knowledge of molecular mechanisms underlying cardiac fibrosis, discusses the potential of imaging and circulating biomarkers available to recognize different phenotypes of this lesion, reviews the currently available and potential future therapies that allow individualized management in reversing progressive fibrosis, as well as the recent progress on proteomic studies of cardiac fibrosis. Proteomic approaches using clinical specimens and animal models can provide the ability to track pathological changes and new insights into the mechanisms underlining cardiac fibrosis. Furthermore, spatial and cell-type resolved quantitative proteomic analysis may also serve as a minimally invasive method for diagnosing cardiac fibrosis and allowing for the initiation of prophylactic treatment.
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