1
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Kampourakis T, Ponnam S, Campbell KS, Wellette-Hunsucker A, Koch D. Cardiac myosin binding protein-C phosphorylation as a function of multiple protein kinase and phosphatase activities. Nat Commun 2024; 15:5111. [PMID: 38877002 PMCID: PMC11178824 DOI: 10.1038/s41467-024-49408-5] [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: 04/27/2023] [Accepted: 06/05/2024] [Indexed: 06/16/2024] Open
Abstract
Phosphorylation of cardiac myosin binding protein-C (cMyBP-C) is a determinant of cardiac myofilament function. Although cMyBP-C phosphorylation by various protein kinases has been extensively studied, the influence of protein phosphatases on cMyBP-C's multiple phosphorylation sites has remained largely obscure. Here we provide a detailed biochemical characterization of cMyBP-C dephosphorylation by protein phosphatases 1 and 2 A (PP1 and PP2A), and develop an integrated kinetic model for cMyBP-C phosphorylation using data for both PP1, PP2A and various protein kinases known to phosphorylate cMyBP-C. We find strong site-specificity and a hierarchical mechanism for both phosphatases, proceeding in the opposite direction of sequential phosphorylation by potein kinase A. The model is consistent with published data from human patients and predicts complex non-linear cMyBP-C phosphorylation patterns that are validated experimentally. Our results suggest non-redundant roles for PP1 and PP2A under both physiological and heart failure conditions, and emphasize the importance of phosphatases for cMyBP-C regulation.
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Affiliation(s)
- Thomas Kampourakis
- Randall Centre for Cell and Molecular Biophysics; and British Heart Foundation Centre of Research Excellence, King's College London, London, SE1 1UL, United Kingdom
| | - Saraswathi Ponnam
- Randall Centre for Cell and Molecular Biophysics; and British Heart Foundation Centre of Research Excellence, King's College London, London, SE1 1UL, United Kingdom
| | - Kenneth S Campbell
- Division of Cardiovascular Medicine, University of Kentucky, Lexington, KY, USA
| | | | - Daniel Koch
- Max Planck Institute for Neurobiology of Behavior-caesar, Ludwig-Erhard-Allee 2, 53175, Bonn, Germany.
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2
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Bonsor DA, Simanshu DK. RAS and SHOC2 Roles in RAF Activation and Therapeutic Considerations. ANNUAL REVIEW OF CANCER BIOLOGY 2024; 8:97-113. [PMID: 38882927 PMCID: PMC11178279 DOI: 10.1146/annurev-cancerbio-062822-030450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2024]
Abstract
Mutations in RAS proteins play a pivotal role in the development of human cancers, driving persistent RAF activation and deregulating the Mitogen-Activated Protein Kinase (MAPK) signaling pathway. While progress has been made in targeting specific oncogenic RAS proteins, effective drug-based therapies for the majority of RAS mutations remain limited. Recent investigations on RAS-RAF complexes and the SHOC2-MRAS-PP1C holoenzyme complex have provided crucial insights into the structural and functional aspects of RAF activation within the MAPK signaling pathway. Moreover, these studies have also unveiled new blueprints for developing inhibitors allowing us to think beyond the current RAS and MEK inhibitors. In this review, we explore the roles of RAS and SHOC2 in activating RAF and discuss potential therapeutic strategies to target these proteins. A comprehensive understanding of the molecular interactions involved in RAF activation and their therapeutic implications holds the potential to drive innovative approaches in combating RAS/RAF-driven cancers.
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Affiliation(s)
- Daniel A. Bonsor
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Dhirendra K. Simanshu
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
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3
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Scardaci R, Berlinska E, Scaparone P, Vietti Michelina S, Garbo E, Novello S, Santamaria D, Ambrogio C. Novel RAF-directed approaches to overcome current clinical limits and block the RAS/RAF node. Mol Oncol 2024; 18:1355-1377. [PMID: 38362705 PMCID: PMC11161739 DOI: 10.1002/1878-0261.13605] [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: 07/24/2023] [Revised: 11/30/2023] [Accepted: 01/30/2024] [Indexed: 02/17/2024] Open
Abstract
Mutations in the RAS-RAF-MEK-ERK pathway are frequent alterations in cancer and RASopathies, and while RAS oncogene activation alone affects 19% of all patients and accounts for approximately 3.4 million new cases every year, less frequent alterations in the cascade's downstream effectors are also involved in cancer etiology. RAS proteins initiate the signaling cascade by promoting the dimerization of RAF kinases, which can act as oncoproteins as well: BRAFV600E is the most common oncogenic driver, mutated in the 8% of all malignancies. Research in this field led to the development of drugs that target the BRAFV600-like mutations (Class I), which are now utilized in clinics, but cause paradoxical activation of the pathway and resistance development. Furthermore, they are ineffective against non-BRAFV600E malignancies that dimerize and could be either RTK/RAS independent or dependent (Class II and III, respectively), which are still lacking an effective treatment. This review discusses the recent advances in anti-RAF therapies, including paradox breakers, dimer-inhibitors, immunotherapies, and other novel approaches, critically evaluating their efficacy in overcoming the therapeutic limitations, and their putative role in blocking the RAS pathway.
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Affiliation(s)
- Rossella Scardaci
- Department of Molecular Biotechnology and Health Sciences, Molecular Biotechnology CenterUniversity of TorinoItaly
| | - Ewa Berlinska
- Department of Molecular Biotechnology and Health Sciences, Molecular Biotechnology CenterUniversity of TorinoItaly
| | - Pietro Scaparone
- Department of Molecular Biotechnology and Health Sciences, Molecular Biotechnology CenterUniversity of TorinoItaly
| | - Sandra Vietti Michelina
- Department of Molecular Biotechnology and Health Sciences, Molecular Biotechnology CenterUniversity of TorinoItaly
| | - Edoardo Garbo
- Department of OncologyUniversity of Torino, San Luigi HospitalOrbassanoItaly
| | - Silvia Novello
- Department of OncologyUniversity of Torino, San Luigi HospitalOrbassanoItaly
| | - David Santamaria
- Centro de Investigación del CáncerCSIC‐Universidad de SalamancaSpain
| | - Chiara Ambrogio
- Department of Molecular Biotechnology and Health Sciences, Molecular Biotechnology CenterUniversity of TorinoItaly
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4
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Gao S, Carrasquillo Rodríguez JW, Bahmanyar S, Airola MV. Structure and mechanism of the human CTDNEP1-NEP1R1 membrane protein phosphatase complex necessary to maintain ER membrane morphology. Proc Natl Acad Sci U S A 2024; 121:e2321167121. [PMID: 38776370 PMCID: PMC11145253 DOI: 10.1073/pnas.2321167121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Accepted: 04/12/2024] [Indexed: 05/25/2024] Open
Abstract
C-terminal Domain Nuclear Envelope Phosphatase 1 (CTDNEP1) is a noncanonical protein serine/threonine phosphatase that has a conserved role in regulating ER membrane biogenesis. Inactivating mutations in CTDNEP1 correlate with the development of medulloblastoma, an aggressive childhood cancer. The transmembrane protein Nuclear Envelope Phosphatase 1 Regulatory Subunit 1 (NEP1R1) binds CTDNEP1, but the molecular details by which NEP1R1 regulates CTDNEP1 function are unclear. Here, we find that knockdown of NEP1R1 generates identical phenotypes to reported loss of CTDNEP1 in mammalian cells, establishing CTDNEP1-NEP1R1 as an evolutionarily conserved membrane protein phosphatase complex that restricts ER expansion. Mechanistically, NEP1R1 acts as an activating regulatory subunit that directly binds and increases the phosphatase activity of CTDNEP1. By defining a minimal NEP1R1 domain sufficient to activate CTDNEP1, we determine high-resolution crystal structures of the CTDNEP1-NEP1R1 complex bound to a peptide sequence acting as a pseudosubstrate. Structurally, NEP1R1 engages CTDNEP1 at a site distant from the active site to stabilize and allosterically activate CTDNEP1. Substrate recognition is facilitated by a conserved Arg residue in CTDNEP1 that binds and orients the substrate peptide in the active site. Together, this reveals mechanisms for how NEP1R1 regulates CTDNEP1 and explains how cancer-associated mutations inactivate CTDNEP1.
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Affiliation(s)
- Shujuan Gao
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY11794
| | | | - Shirin Bahmanyar
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT06511
| | - Michael V. Airola
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY11794
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5
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Pfisterer M, Robert R, Saul VV, Pritz A, Seibert M, Feederle R, Schmitz ML. The Aurora B-controlled PP1/RepoMan complex determines the spatial and temporal distribution of mitotic H2B S6 phosphorylation. Open Biol 2024; 14:230460. [PMID: 38806145 PMCID: PMC11293436 DOI: 10.1098/rsob.230460] [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: 12/21/2023] [Revised: 02/02/2024] [Accepted: 03/19/2024] [Indexed: 05/30/2024] Open
Abstract
The precise spatial and temporal control of histone phosphorylations is important for the ordered progression through the different phases of mitosis. The phosphorylation of H2B at S6 (H2B S6ph), which is crucial for chromosome segregation, reaches its maximum level during metaphase and is limited to the inner centromere. We discovered that the temporal and spatial regulation of this modification, as well as its intensity, are governed by the scaffold protein RepoMan and its associated catalytically active phosphatases, PP1α and PP1γ. Phosphatase activity is inhibited at the area of maximal H2B S6 phosphorylation at the inner centromere by site-specific Aurora B-mediated inactivation of the PP1/RepoMan complex. The motor protein Mklp2 contributes to the relocalization of Aurora B from chromatin to the mitotic spindle during anaphase, thus alleviating Aurora B-dependent repression of the PP1/RepoMan complex and enabling dephosphorylation of H2B S6. Accordingly, dysregulation of Mklp2 levels, as commonly observed in tumour cells, leads to the lack of H2B S6 dephosphorylation during early anaphase, which might contribute to chromosomal instability.
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Affiliation(s)
| | - Roman Robert
- Institute of Biochemistry, Justus-Liebig-University Giessen, Giessen, Germany
| | - Vera V. Saul
- Institute of Biochemistry, Justus-Liebig-University Giessen, Giessen, Germany
| | - Amelie Pritz
- Institute of Biochemistry, Justus-Liebig-University Giessen, Giessen, Germany
| | - Markus Seibert
- Institute of Biochemistry, Justus-Liebig-University Giessen, Giessen, Germany
| | - Regina Feederle
- Monoclonal Antibody Core Facility, Helmholtz Center Munich, German Research Center for Environmental Health, Neuherberg, Germany
| | - M. Lienhard Schmitz
- Institute of Biochemistry, Justus-Liebig-University Giessen, Giessen, Germany
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6
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Corda PO, Bollen M, Ribeiro D, Fardilha M. Emerging roles of the Protein Phosphatase 1 (PP1) in the context of viral infections. Cell Commun Signal 2024; 22:65. [PMID: 38267954 PMCID: PMC10807198 DOI: 10.1186/s12964-023-01468-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 12/30/2023] [Indexed: 01/26/2024] Open
Abstract
Protein Phosphatase 1 (PP1) is a major serine/threonine phosphatase in eukaryotes, participating in several cellular processes and metabolic pathways. Due to their low substrate specificity, PP1's catalytic subunits do not exist as free entities but instead bind to Regulatory Interactors of Protein Phosphatase One (RIPPO), which regulate PP1's substrate specificity and subcellular localization. Most RIPPOs bind to PP1 through combinations of short linear motifs (4-12 residues), forming highly specific PP1 holoenzymes. These PP1-binding motifs may, hence, represent attractive targets for the development of specific drugs that interfere with a subset of PP1 holoenzymes. Several viruses exploit the host cell protein (de)phosphorylation machinery to ensure efficient virus particle formation and propagation. While the role of many host cell kinases in viral life cycles has been extensively studied, the targeting of phosphatases by viral proteins has been studied in less detail. Here, we compile and review what is known concerning the role of PP1 in the context of viral infections and discuss how it may constitute a putative host-based target for the development of novel antiviral strategies.
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Affiliation(s)
- Pedro O Corda
- Institute of Biomedicine (iBiMED), Department of Medical Sciences, University of Aveiro, Aveiro, Portugal
| | - Mathieu Bollen
- Department of Cellular and Molecular Medicine, Laboratory of Biosignaling & Therapeutics, Katholieke Universiteit Leuven, Louvain, Belgium
| | - Daniela Ribeiro
- Institute of Biomedicine (iBiMED), Department of Medical Sciences, University of Aveiro, Aveiro, Portugal.
| | - Margarida Fardilha
- Institute of Biomedicine (iBiMED), Department of Medical Sciences, University of Aveiro, Aveiro, Portugal.
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7
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Padi SKR, Vos MR, Godek RJ, Fuller JR, Kruse T, Hein JB, Nilsson J, Kelker MS, Page R, Peti W. Cryo-EM structures of PP2A:B55-FAM122A and PP2A:B55-ARPP19. Nature 2024; 625:195-203. [PMID: 38123684 PMCID: PMC10765524 DOI: 10.1038/s41586-023-06870-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Accepted: 11/15/2023] [Indexed: 12/23/2023]
Abstract
Progression through the cell cycle is controlled by regulated and abrupt changes in phosphorylation1. Mitotic entry is initiated by increased phosphorylation of mitotic proteins, a process driven by kinases2, whereas mitotic exit is achieved by counteracting dephosphorylation, a process driven by phosphatases, especially PP2A:B553. Although the role of kinases in mitotic entry is well established, recent data have shown that mitosis is only successfully initiated when the counterbalancing phosphatases are also inhibited4. Inhibition of PP2A:B55 is achieved by the intrinsically disordered proteins ARPP195,6 and FAM122A7. Despite their critical roles in mitosis, the mechanisms by which they achieve PP2A:B55 inhibition is unknown. Here, we report the single-particle cryo-electron microscopy structures of PP2A:B55 bound to phosphorylated ARPP19 and FAM122A. Consistent with our complementary NMR spectroscopy studies, both intrinsically disordered proteins bind PP2A:B55, but do so in highly distinct manners, leveraging multiple distinct binding sites on B55. Our extensive structural, biophysical and biochemical data explain how substrates and inhibitors are recruited to PP2A:B55 and provide a molecular roadmap for the development of therapeutic interventions for PP2A:B55-related diseases.
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Affiliation(s)
- Sathish K R Padi
- Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, CT, USA
| | - Margaret R Vos
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT, USA
| | - Rachel J Godek
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT, USA
| | | | - Thomas Kruse
- The Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Copenhagen, Denmark
| | - Jamin B Hein
- The Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Copenhagen, Denmark
| | - Jakob Nilsson
- The Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Copenhagen, Denmark
| | | | - Rebecca Page
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT, USA.
| | - Wolfgang Peti
- Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, CT, USA.
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8
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Aboonabi A, McCauley MD. Myofilament dysfunction in diastolic heart failure. Heart Fail Rev 2024; 29:79-93. [PMID: 37837495 PMCID: PMC10904515 DOI: 10.1007/s10741-023-10352-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/18/2023] [Indexed: 10/16/2023]
Abstract
Diastolic heart failure (DHF), in which impaired ventricular filling leads to typical heart failure symptoms, represents over 50% of all heart failure cases and is linked with risk factors, including metabolic syndrome, hypertension, diabetes, and aging. A substantial proportion of patients with this disorder maintain normal left ventricular systolic function, as assessed by ejection fraction. Despite the high prevalence of DHF, no effective therapeutic agents are available to treat this condition, partially because the molecular mechanisms of diastolic dysfunction remain poorly understood. As such, by focusing on the underlying molecular and cellular processes contributing to DHF can yield new insights that can represent an exciting new avenue and propose a novel therapeutic approach for DHF treatment. This review discusses new developments from basic and clinical/translational research to highlight current knowledge gaps, help define molecular determinants of diastolic dysfunction, and clarify new targets for treatment.
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Affiliation(s)
- Anahita Aboonabi
- Division of Cardiology, Department of Medicine, College of Medicine, University of Illinois at Chicago, 840 S. Wood St., 920S (MC 715), Chicago, IL, 60612, USA.
- Jesse Brown VA Medical Center, Chicago, IL, USA.
| | - Mark D McCauley
- Division of Cardiology, Department of Medicine, College of Medicine, University of Illinois at Chicago, 840 S. Wood St., 920S (MC 715), Chicago, IL, 60612, USA.
- Jesse Brown VA Medical Center, Chicago, IL, USA.
- Department of Physiology and Biophysics and the Center for Cardiovascular Research, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA.
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9
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Carminati M, Rodríguez-Molina JB, Manav MC, Bellini D, Passmore LA. A direct interaction between CPF and RNA Pol II links RNA 3' end processing to transcription. Mol Cell 2023; 83:4461-4478.e13. [PMID: 38029752 PMCID: PMC10783616 DOI: 10.1016/j.molcel.2023.11.004] [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: 06/20/2022] [Revised: 09/25/2023] [Accepted: 11/06/2023] [Indexed: 12/01/2023]
Abstract
Transcription termination by RNA polymerase II (RNA Pol II) is linked to RNA 3' end processing by the cleavage and polyadenylation factor (CPF or CPSF). CPF contains endonuclease, poly(A) polymerase, and protein phosphatase activities, which cleave and polyadenylate pre-mRNAs and dephosphorylate RNA Pol II to control transcription. Exactly how the RNA 3' end processing machinery is coupled to transcription remains unclear. Here, we combine in vitro reconstitution, structural studies, and genome-wide analyses to show that yeast CPF physically and functionally interacts with RNA Pol II. Surprisingly, CPF-mediated dephosphorylation promotes the formation of an RNA Pol II stalk-to-stalk homodimer in vitro. This dimer is compatible with transcription but not with the binding of transcription elongation factors. Disruption of the dimerization interface in cells causes transcription defects, including altered RNA Pol II abundance on protein-coding genes, tRNA genes, and intergenic regions. We hypothesize that RNA Pol II dimerization may provide a mechanistic basis for the allosteric model of transcription termination.
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Affiliation(s)
| | | | - M Cemre Manav
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | - Dom Bellini
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
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10
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Ji YX, Hu S, Chen FX. Protocol for rapidly inducing genome-wide RNA Pol II hyperphosphorylation by selectively disrupting INTAC phosphatase activity. STAR Protoc 2023; 4:102640. [PMID: 37831607 PMCID: PMC10589876 DOI: 10.1016/j.xpro.2023.102640] [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: 07/31/2023] [Revised: 09/08/2023] [Accepted: 09/22/2023] [Indexed: 10/15/2023] Open
Abstract
While several inhibitors targeting RNA polymerase II (Pol II) kinases have been applied for inhibiting RNA Pol II phosphorylation, there are few approaches for inducing RNA Pol II hyperphosphorylation. Here, we present a protocol for constructing the INTS8 degradation tag (dTAG) system combined with ectopic expression of N-terminally truncated INTS8 (INTS8-ΔN) in DLD-1 cells. We describe steps for INTS8-dTAG cell line construction, validation of knockin and degradation, and INTS8-ΔN rescue. We then detail validation of RNA Pol II phosphorylation upregulation. For complete details on the use and execution of this protocol, please refer to Hu et al. (2023).1.
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Affiliation(s)
- Yu-Xin Ji
- Fudan University Shanghai Cancer Center, Shanghai Key Laboratory of Medical Epigenetics, Shanghai Key Laboratory of Radiation Oncology, Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Shibin Hu
- Fudan University Shanghai Cancer Center, Shanghai Key Laboratory of Medical Epigenetics, Shanghai Key Laboratory of Radiation Oncology, Institutes of Biomedical Sciences, Fudan University, Shanghai, China.
| | - Fei Xavier Chen
- Fudan University Shanghai Cancer Center, Shanghai Key Laboratory of Medical Epigenetics, Shanghai Key Laboratory of Radiation Oncology, Institutes of Biomedical Sciences, Fudan University, Shanghai, China.
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11
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Fonódi M, Thalwieser Z, Csortos C, Boratkó A. TIMAP, a Regulatory Subunit of Protein Phosphatase 1, Inhibits In Vitro Neuronal Differentiation. Int J Mol Sci 2023; 24:17360. [PMID: 38139189 PMCID: PMC10744335 DOI: 10.3390/ijms242417360] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2023] [Revised: 12/06/2023] [Accepted: 12/07/2023] [Indexed: 12/24/2023] Open
Abstract
TIMAP (TGF-β-inhibited membrane associated protein) is abundant in endothelial cells, and it has been regarded as a member of the myosin phosphatase targeting protein (MYPT) family. Our workgroup previously identified several interacting protein partners of TIMAP and proved its regulatory subunit role for protein phosphatase 1 catalytic subunit (PP1c). TIMAP is also expressed in neuronal cells, but details of its function have not been studied yet. Therefore, we aimed to explore the role of TIMAP in neuronal cells, especially during differentiation. Expression of TIMAP was proved both at mRNA and protein levels in SH-SY5Y human neuroblastoma cells. Differentiation of SH-SY5Y cells was optimized and proved by the detection of neuronal differentiation markers, such as β3-tubulin, nestin and inhibitor of differentiation 1 (ID1) using qPCR and Western blot. We found downregulation of TIMAP during differentiation. In accordance with this, overexpression of recombinant TIMAP attenuated the differentiation of neuronal cells. Moreover, the subcellular localization of TIMAP has changed during differentiation as it translocated from the plasma membrane into the nucleus. The nuclear interactome of TIMAP revealed more than 50 proteins, offering the possibility to further investigate the role of TIMAP in several key physiological pathways of neuronal cells.
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Affiliation(s)
| | | | | | - Anita Boratkó
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Egyetem Tér 1, H-4032 Debrecen, Hungary; (M.F.); (Z.T.); (C.C.)
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12
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Hicks D, Giresh K, Wrischnik LA, Weiser DC. The PPP1R15 Family of eIF2-alpha Phosphatase Targeting Subunits (GADD34 and CReP). Int J Mol Sci 2023; 24:17321. [PMID: 38139150 PMCID: PMC10743859 DOI: 10.3390/ijms242417321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2023] [Revised: 12/01/2023] [Accepted: 12/08/2023] [Indexed: 12/24/2023] Open
Abstract
The vertebrate PPP1R15 family consists of the proteins GADD34 (growth arrest and DNA damage-inducible protein 34, the product of the PPP1R15A gene) and CReP (constitutive repressor of eIF2α phosphorylation, the product of the PPP1R15B gene), both of which function as targeting/regulatory subunits for protein phosphatase 1 (PP1) by regulating subcellular localization, modulating substrate specificity and assembling complexes with target proteins. The primary cellular function of these proteins is to facilitate the dephosphorylation of eukaryotic initiation factor 2-alpha (eIF2α) by PP1 during cell stress. In this review, we will provide a comprehensive overview of the cellular function, biochemistry and pharmacology of GADD34 and CReP, starting with a brief introduction of eIF2α phosphorylation via the integrated protein response (ISR). We discuss the roles GADD34 and CReP play as feedback inhibitors of the unfolded protein response (UPR) and highlight the critical function they serve as inhibitors of the PERK-dependent branch, which is particularly important since it can mediate cell survival or cell death, depending on how long the stressful stimuli lasts, and GADD34 and CReP play key roles in fine-tuning this cellular decision. We briefly discuss the roles of GADD34 and CReP homologs in model systems and then focus on what we have learned about their function from knockout mice and human patients, followed by a brief review of several diseases in which GADD34 and CReP have been implicated, including cancer, diabetes and especially neurodegenerative disease. Because of the potential importance of GADD34 and CReP in aspects of human health and disease, we will discuss several pharmacological inhibitors of GADD34 and/or CReP that show promise as treatments and the controversies as to their mechanism of action. This review will finish with a discussion of the biochemical properties of GADD34 and CReP, their regulation and the additional interacting partners that may provide insight into the roles these proteins may play in other cellular pathways. We will conclude with a brief outline of critical areas for future study.
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Affiliation(s)
- Danielle Hicks
- Department of Science, Mathematics and Engineering, Modesto Junior College, Modesto, CA 95350, USA
- Department of Biological Sciences, University of the Pacific, Stockton, CA 95211, USA
| | - Krithika Giresh
- Department of Biological Sciences, University of the Pacific, Stockton, CA 95211, USA
| | - Lisa A. Wrischnik
- Department of Biological Sciences, University of the Pacific, Stockton, CA 95211, USA
| | - Douglas C. Weiser
- Department of Biological Sciences, University of the Pacific, Stockton, CA 95211, USA
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13
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Song S, Cho B, Weiner AT, Nissen SB, Ojeda Naharros I, Sanchez Bosch P, Suyama K, Hu Y, He L, Svinkina T, Udeshi ND, Carr SA, Perrimon N, Axelrod JD. Protein phosphatase 1 regulates core PCP signaling. EMBO Rep 2023; 24:e56997. [PMID: 37975164 PMCID: PMC10702827 DOI: 10.15252/embr.202356997] [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: 02/13/2023] [Revised: 10/24/2023] [Accepted: 10/26/2023] [Indexed: 11/19/2023] Open
Abstract
Planar cell polarity (PCP) signaling polarizes epithelial cells within the plane of an epithelium. Core PCP signaling components adopt asymmetric subcellular localizations within cells to both polarize and coordinate polarity between cells. Achieving subcellular asymmetry requires additional effectors, including some mediating post-translational modifications of core components. Identification of such proteins is challenging due to pleiotropy. We used mass spectrometry-based proximity labeling proteomics to identify such regulators in the Drosophila wing. We identified the catalytic subunit of protein phosphatase1, Pp1-87B, and show that it regulates core protein polarization. Pp1-87B interacts with the core protein Van Gogh and at least one serine/threonine kinase, Dco/CKIε, that is known to regulate PCP. Pp1-87B modulates Van Gogh subcellular localization and directs its dephosphorylation in vivo. PNUTS, a Pp1 regulatory subunit, also modulates PCP. While the direct substrate(s) of Pp1-87B in control of PCP is not known, our data support the model that cycling between phosphorylated and unphosphorylated forms of one or more core PCP components may regulate acquisition of asymmetry. Finally, our screen serves as a resource for identifying additional regulators of PCP signaling.
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Affiliation(s)
- Song Song
- Department of PathologyStanford University School of MedicineStanfordCAUSA
- Present address:
GenScriptPiscatawayNJUSA
| | - Bomsoo Cho
- Department of PathologyStanford University School of MedicineStanfordCAUSA
| | - Alexis T Weiner
- Department of PathologyStanford University School of MedicineStanfordCAUSA
| | - Silas Boye Nissen
- Department of PathologyStanford University School of MedicineStanfordCAUSA
- The Novo Nordisk Foundation Center for Stem Cell Medicine (reNEW)University of CopenhagenCopenhagenDenmark
| | - Irene Ojeda Naharros
- Department of OphthalmologyUniversity of California, San FranciscoSan FranciscoCAUSA
| | | | - Kaye Suyama
- Department of PathologyStanford University School of MedicineStanfordCAUSA
| | - Yanhui Hu
- Department of Genetics, Blavatnik Institute, Harvard Medical SchoolHarvard UniversityBostonMAUSA
| | - Li He
- Department of Genetics, Blavatnik Institute, Harvard Medical SchoolHarvard UniversityBostonMAUSA
- Present address:
School of Life SciencesUniversity of Science and Technology of ChinaHefeiChina
| | | | | | | | - Norbert Perrimon
- Department of Genetics, Blavatnik Institute, Harvard Medical SchoolHarvard UniversityBostonMAUSA
- Howard Hughes Medical InstituteBostonMAUSA
| | - Jeffrey D Axelrod
- Department of PathologyStanford University School of MedicineStanfordCAUSA
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14
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Zhang Y, Sabatini R. Leishmania PNUTS discriminates between PP1 catalytic subunits through an RVxF-ΦΦ-F motif and polymorphisms in the PP1 C-tail and catalytic domain. J Biol Chem 2023; 299:105432. [PMID: 37926279 PMCID: PMC10731240 DOI: 10.1016/j.jbc.2023.105432] [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: 09/08/2023] [Revised: 10/10/2023] [Accepted: 10/23/2023] [Indexed: 11/07/2023] Open
Abstract
Phosphoprotein phosphatase 1 (PP1) associates with specific regulatory subunits to achieve, among other functions, substrate selectivity. Among the eight PP1 isotypes in Leishmania, PP1-8e associates with the regulatory protein PNUTS along with the structural factors JBP3 and Wdr82 in the PJW/PP1 complex that modulates RNA polymerase II (pol II) phosphorylation and transcription termination. Little is known regarding interactions involved in PJW/PP1 complex formation, including how PP1-8e is the selective isotype associated with PNUTS. Here, we show that PNUTS uses an established RVxF-ΦΦ-F motif to bind the PP1 catalytic domain with similar interfacial interactions as mammalian PP1-PNUTS and noncanonical motifs. These atypical interactions involve residues within the PP1-8e catalytic domain and N and C terminus for isoform-specific regulator binding. This work advances our understanding of PP1 isoform selectivity and reveals key roles of PP1 residues in regulator binding. We also explore the role of PNUTS as a scaffold protein for the complex by identifying the C-terminal region involved in binding JBP3 and Wdr82 and impact of PNUTS on the stability of complex components and function in pol II transcription in vivo. Taken together, these studies provide a potential mechanism where multiple motifs within PNUTS are used combinatorially to tune binding affinity to PP1, and the C terminus for JBP3 and Wdr82 association, in the Leishmania PJW/PP1 complex. Overall, our data provide insights in the formation of the PJW/PP1 complex involved in regulating pol II transcription in divergent protozoans where little is understood.
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Affiliation(s)
- Yang Zhang
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, USA
| | - Robert Sabatini
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, USA.
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15
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Alba-Posse EJ, Bruque CD, Gándola Y, Gasulla J, Nadra AD. From in-silico screening to in-vitro evaluation: Enhancing the detection of Microcystins with engineered PP1 mutant variants. J Struct Biol 2023; 215:108043. [PMID: 37935286 DOI: 10.1016/j.jsb.2023.108043] [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: 07/15/2023] [Revised: 10/20/2023] [Accepted: 11/04/2023] [Indexed: 11/09/2023]
Abstract
Cyanotoxins produced during harmful algal blooms (CyanoHABs) have become a worldwide issue of concern. Microcystins (MC) are the most ubiquitous group of cyanotoxins and have known carcinogenic and hepatotoxic effects. The protein phosphatase inhibition assays (PPIAs), based on the inhibition of Protein Phosphatase 1/2A (PP1/PP2A) by MC, are one of the most cost-effective options for detecting MC. In this work, we aimed to design in-silico and evaluate in-vitro mutant variants of the PP1 protein, in order to enhance their capabilities as a MC biosensor. To this end, we performed an in-silico active site-saturated mutagenesis screening, followed by stability and docking affinity calculation with the MCLR cyanotoxin. Candidates with improved both affinity and stability were further tested in a fully flexible active-site docking. The best-scored mutations (19) were individually analysed regarding their locations and interactions. Four of them (p.D197F; p.Q249Y; p.S129W; p.D220Q) were selected for in-vitro expression and evaluation. Mutant p.D197F, exhibited a significant increment in inhibition by MCLR with respect to the WT, while showing a non-significant difference in stability nor activity. This successful PP1 inhibition enhancement suggests the potential of the p.D197F variant for practical MC detection applications.
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Affiliation(s)
- Ezequiel J Alba-Posse
- Facultad de Ciencias Exactas y Naturales, Departamento de Fisiología y Biología Molecular y Celular, Instituto de Biociencias, Biotecnología y Biología Traslacional (iB3), Universidad de Buenos Aires, Intendente Güiraldes 2160, C1428EGA Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Godoy Cruz 2290, C1425FQB Buenos Aires, Argentina
| | - Carlos David Bruque
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Godoy Cruz 2290, C1425FQB Buenos Aires, Argentina; Unidad de Conocimiento Traslacional Hospitalaria Patagónica, Hospital de Alta Complejidad El Calafate - S.A.M.I.C., Jorge Newbery 453, CP9405 El Calafate, Santa Cruz, Argentina
| | - Yamila Gándola
- Facultad de Ciencias Exactas y Naturales, Departamento de Fisiología y Biología Molecular y Celular, Instituto de Biociencias, Biotecnología y Biología Traslacional (iB3), Universidad de Buenos Aires, Intendente Güiraldes 2160, C1428EGA Buenos Aires, Argentina
| | - Javier Gasulla
- Facultad de Ciencias Exactas y Naturales, Departamento de Fisiología y Biología Molecular y Celular, Instituto de Biociencias, Biotecnología y Biología Traslacional (iB3), Universidad de Buenos Aires, Intendente Güiraldes 2160, C1428EGA Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Godoy Cruz 2290, C1425FQB Buenos Aires, Argentina.
| | - Alejandro D Nadra
- Facultad de Ciencias Exactas y Naturales, Departamento de Fisiología y Biología Molecular y Celular, Instituto de Biociencias, Biotecnología y Biología Traslacional (iB3), Universidad de Buenos Aires, Intendente Güiraldes 2160, C1428EGA Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Godoy Cruz 2290, C1425FQB Buenos Aires, Argentina.
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16
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Gao S, Carrasquillo Rodríguez JW, Bahmanyar S, Airola MV. Structure and mechanism of the human CTDNEP1-NEP1R1 membrane protein phosphatase complex necessary to maintain ER membrane morphology. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.20.567952. [PMID: 38045299 PMCID: PMC10690229 DOI: 10.1101/2023.11.20.567952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
C-terminal Domain Nuclear Envelope Phosphatase 1 (CTDNEP1) is a non-canonical protein serine/threonine phosphatase that regulates ER membrane biogenesis. Inactivating mutations in CTDNEP1 correlate with development of medulloblastoma, an aggressive childhood cancer. The transmembrane protein Nuclear Envelope Phosphatase 1 Regulatory Subunit 1 (NEP1R1) binds CTDNEP1, but the molecular details by which NEP1R1 regulates CTDNEP1 function are unclear. Here, we find that knockdown of CTDNEP1 or NEP1R1 in human cells generate identical phenotypes, establishing CTDNEP1-NEP1R1 as an evolutionarily conserved membrane protein phosphatase complex that restricts ER expansion. Mechanistically, NEP1R1 acts as an activating regulatory subunit that directly binds and increases the phosphatase activity of CTDNEP1. By defining a minimal NEP1R1 domain sufficient to activate CTDNEP1, we determine high resolution crystal structures of the CTDNEP1-NEP1R1 complex bound to a pseudo-substrate. Structurally, NEP1R1 engages CTDNEP1 at a site distant from the active site to stabilize and allosterically activate CTDNEP1. Substrate recognition is facilitated by a conserved Arg residue that binds and orients the substrate peptide in the active site. Together, this reveals mechanisms for how NEP1R1 regulates CTDNEP1 and explains how cancer-associated mutations inactivate CTDNEP1.
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Affiliation(s)
- Shujuan Gao
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook NY 11794, USA
| | | | - Shirin Bahmanyar
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06511, USA
| | - Michael V. Airola
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook NY 11794, USA
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17
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Bonsor DA, Simanshu DK. Structural insights into the role of SHOC2-MRAS-PP1C complex in RAF activation. FEBS J 2023; 290:4852-4863. [PMID: 37074066 PMCID: PMC10584989 DOI: 10.1111/febs.16800] [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: 02/17/2023] [Revised: 04/07/2023] [Accepted: 04/18/2023] [Indexed: 04/20/2023]
Abstract
RAF activation is a key step for signalling through the mitogen-activated protein kinase (MAPK) pathway. The SHOC2 protein, along with MRAS and PP1C, forms a high affinity, heterotrimeric holoenzyme that activates RAF kinases by dephosphorylating a specific phosphoserine. Recently, our research, along with that of three other teams, has uncovered valuable structural and functional insights into the SHOC2-MRAS-PP1C (SMP) holoenzyme complex. In this structural snapshot, we review SMP complex assembly, the dependency on the bound-nucleotide state of MRAS, the substitution of MRAS by the canonical RAS proteins and the roles of SHOC2 and MRAS on PP1C activity and specificity. Furthermore, we discuss the effect of several RASopathy mutations identified within the SMP complex and explore potential therapeutic approaches for targeting the SMP complex in RAS/RAF-driven cancers and RASopathies.
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Affiliation(s)
- Daniel A. Bonsor
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Dhirendra K. Simanshu
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
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18
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Zhang Y, Sabatini R. Leishmania PNUTS discriminates between PP1 catalytic subunits through a RVxF-ΦΦ-F motif and polymorphisms in the PP1 C-tail and catalytic domain. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.20.558696. [PMID: 37790576 PMCID: PMC10542515 DOI: 10.1101/2023.09.20.558696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
PP1 phosphatases lack substrate specificity and associate with specific regulatory subunits to achieve selectivity. Among the eight PP1 isotypes in Leishmania, PP1-8e associates with the regulatory protein PNUTS along with the structural factors JBP3 and Wdr82 in the PJW/PP1 complex that modulates RNA polymerase II (Pol II) phosphorylation and transcription termination. Little is known regarding interactions involved in PJW/PP1 complex formation, including how PP1-8e is the selective isotype associated with PNUTS. Here, we show that PNUTS uses an established RVxF-ΦΦ-F motif to bind the PP1 catalytic domain with similar interfacial interactions as mammalian PP1- PNUTS and non-canonical motifs. These atypical interactions involve residues within the PP1-8e catalytic domain and N- and C-terminus for isoform specific regulator binding. This work advances our understanding of PP1 isoform selectivity and reveals key roles of PP1 residues in regulator binding. We also explore the role of PNUTS as a scaffold protein for the complex by identifying the C-terminal region involved in binding JBP3 and Wdr82, and impact of PNUTS on the stability of complex components and function in Pol II transcription in vivo . Taken together, these studies provide a potential mechanism where multiple motifs within PNUTS are used combinatorially to tune binding affinity to PP1, and the C-termini for independent binding of JBP3 and Wdr82, in the Leishmania PJW/PP1 complex. Overall, our data provide insights in the formation of the PJW/PP1 complex involved in regulating Pol II transcription in divergent protozoans where little is understood.
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19
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Song S, Cho B, Weiner AT, Nissen SB, Naharros IO, Bosch PS, Suyama K, Hu Y, He L, Svinkina T, Udeshi ND, Carr SA, Perrimon N, Axelrod JD. Protein phosphatase 1 regulates core PCP signaling. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.12.556998. [PMID: 37745534 PMCID: PMC10515792 DOI: 10.1101/2023.09.12.556998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
PCP signaling polarizes epithelial cells within the plane of an epithelium. Core PCP signaling components adopt asymmetric subcellular localizations within cells to both polarize and coordinate polarity between cells. Achieving subcellular asymmetry requires additional effectors, including some mediating post-translational modifications of core components. Identification of such proteins is challenging due to pleiotropy. We used mass spectrometry-based proximity labeling proteomics to identify such regulators in the Drosophila wing. We identified the catalytic subunit of Protein Phosphatase1, Pp1-87B, and show that it regulates core protein polarization. Pp1-87B interacts with the core protein Van Gogh and at least one Serine/Threonine kinase, Dco/CKIε, that is known to regulate PCP. Pp1-87B modulates Van Gogh subcellular localization and directs its dephosphorylation in vivo. PNUTS, a Pp1 regulatory subunit, also modulates PCP. While the direct substrate(s) of Pp1-87B in control of PCP is not known, our data support the model that cycling between phosphorylated and unphosphorylated forms of one or more core PCP components may regulate acquisition of asymmetry. Finally, our screen serves as a resource for identifying additional regulators of PCP signaling.
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Affiliation(s)
- Song Song
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
- Present Address: GenScript, 860 Centennial Avenue, Piscataway, NJ, 08854, USA
| | - Bomsoo Cho
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Alexis T. Weiner
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Silas Boye Nissen
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
- The Novo Nordisk Foundation Center for Stem Cell Medicine (reNEW), University of Copenhagen, Blegdamsvej 3B, DK-2200 Copenhagen N, Denmark
| | - Irene Ojeda Naharros
- Department of Ophthalmology, University of California, San Francisco, San Francisco, CA 94143-3120, USA
| | - Pablo Sanchez Bosch
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Kaye Suyama
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Yanhui Hu
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Harvard University, Boston, MA 02115, USA
| | - Li He
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Harvard University, Boston, MA 02115, USA
- Present Address: School of Life Sciences, University of Science and Technology of China, Hefei 230027, China
| | | | | | | | - Norbert Perrimon
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Harvard University, Boston, MA 02115, USA
- Howard Hughes Medical Institute, Boston, MA 02138, USA
| | - Jeffrey D. Axelrod
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
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20
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Padi SK, Vos MR, Godek RJ, Fuller JR, Kruse T, Hein JB, Nilsson J, Kelker MS, Page R, Peti W. Cryo-EM structures of PP2A:B55-FAM122A and PP2A:B55-ARPP19. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.31.555365. [PMID: 37693408 PMCID: PMC10491220 DOI: 10.1101/2023.08.31.555365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Progression through the cell cycle is controlled by regulated and abrupt changes in phosphorylation.1 Mitotic entry is initiated by increased phosphorylation of mitotic proteins, a process driven by kinases,2 while mitotic exit is achieved by counteracting dephosphorylation, a process driven by phosphatases, especially PP2A:B55.3 While the role of kinases in mitotic entry is well-established, recent data have shown that mitosis is only successfully initiated when the counterbalancing phosphatases are also inhibited.4 For PP2A:B55, inhibition is achieved by the two intrinsically disordered proteins (IDPs), ARPP19 (phosphorylation-dependent)6,7 and FAM122A5 (inhibition is phosphorylation-independent). Despite their critical roles in mitosis, the mechanisms by which they achieve PP2A:B55 inhibition is unknown. Here, we report the cryo-electron microscopy structures of PP2A:B55 bound to phosphorylated ARPP19 and FAM122A. Consistent with our complementary NMR spectroscopy studies both IDPs bind PP2A:B55, but do so in highly distinct manners, unexpectedly leveraging multiple distinct binding sites on B55. Our extensive structural, biophysical and biochemical data explain how substrates and inhibitors are recruited to PP2A:B55 and provides a molecular roadmap for the development of therapeutic interventions for PP2A:B55 related diseases.
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Affiliation(s)
- Sathish K.R. Padi
- Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, USA
| | - Margaret R. Vos
- Department of Cell Biology, University of Connecticut Health Center, Farmington, USA
| | - Rachel J. Godek
- Department of Cell Biology, University of Connecticut Health Center, Farmington, USA
| | | | - Thomas Kruse
- The Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Copenhagen, Denmark
| | - Jamin B. Hein
- The Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Copenhagen, Denmark
| | - Jakob Nilsson
- The Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Copenhagen, Denmark
| | | | - Rebecca Page
- Department of Cell Biology, University of Connecticut Health Center, Farmington, USA
| | - Wolfgang Peti
- Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, USA
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21
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Mansour H, Cabezas-Cruz A, Peucelle V, Farce A, Salomé-Desnoulez S, Metatla I, Guerrera IC, Hollin T, Khalife J. Characterization of GEXP15 as a Potential Regulator of Protein Phosphatase 1 in Plasmodium falciparum. Int J Mol Sci 2023; 24:12647. [PMID: 37628837 PMCID: PMC10454571 DOI: 10.3390/ijms241612647] [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: 07/04/2023] [Revised: 07/29/2023] [Accepted: 08/04/2023] [Indexed: 08/27/2023] Open
Abstract
The Protein Phosphatase type 1 catalytic subunit (PP1c) (PF3D7_1414400) operates in combination with various regulatory proteins to specifically direct and control its phosphatase activity. However, there is little information about this phosphatase and its regulators in the human malaria parasite, Plasmodium falciparum. To address this knowledge gap, we conducted a comprehensive investigation into the structural and functional characteristics of a conserved Plasmodium-specific regulator called Gametocyte EXported Protein 15, GEXP15 (PF3D7_1031600). Through in silico analysis, we identified three significant regions of interest in GEXP15: an N-terminal region housing a PP1-interacting RVxF motif, a conserved domain whose function is unknown, and a GYF-like domain that potentially facilitates specific protein-protein interactions. To further elucidate the role of GEXP15, we conducted in vitro interaction studies that demonstrated a direct interaction between GEXP15 and PP1 via the RVxF-binding motif. This interaction was found to enhance the phosphatase activity of PP1. Additionally, utilizing a transgenic GEXP15-tagged line and live microscopy, we observed high expression of GEXP15 in late asexual stages of the parasite, with localization predominantly in the nucleus. Immunoprecipitation assays followed by mass spectrometry analyses revealed the interaction of GEXP15 with ribosomal- and RNA-binding proteins. Furthermore, through pull-down analyses of recombinant functional domains of His-tagged GEXP15, we confirmed its binding to the ribosomal complex via the GYF domain. Collectively, our study sheds light on the PfGEXP15-PP1-ribosome interaction, which plays a crucial role in protein translation. These findings suggest that PfGEXP15 could serve as a potential target for the development of malaria drugs.
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Affiliation(s)
- Hala Mansour
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019-UMR 9017-CIIL-Center for Infection and Immunity of Lille, 59000 Lille, France; (H.M.); (V.P.)
| | - Alejandro Cabezas-Cruz
- ANSES, INRAE, Ecole Nationale Vétérinaire d’Alfort, UMR BIPAR, Laboratoire de Santé Animale, 94700 Maisons-Alfort, France;
| | - Véronique Peucelle
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019-UMR 9017-CIIL-Center for Infection and Immunity of Lille, 59000 Lille, France; (H.M.); (V.P.)
| | - Amaury Farce
- Univ. Lille, Inserm, CHU Lille, U1286–Infinite–Institute for Translational Research in Inflammation, 59000 Lille, France;
| | - Sophie Salomé-Desnoulez
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, US 41–UAR 2014–PLBS, 59000 Lille, France;
| | - Ines Metatla
- Proteomics Platform Necker, Université Paris Cité–Structure Fédérative de Recherche Necker, INSERM US24/CNRS UAR3633, 75015 Paris, France; (I.M.); (I.C.G.)
| | - Ida Chiara Guerrera
- Proteomics Platform Necker, Université Paris Cité–Structure Fédérative de Recherche Necker, INSERM US24/CNRS UAR3633, 75015 Paris, France; (I.M.); (I.C.G.)
| | - Thomas Hollin
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019-UMR 9017-CIIL-Center for Infection and Immunity of Lille, 59000 Lille, France; (H.M.); (V.P.)
- Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, CA 92521, USA
| | - Jamal Khalife
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019-UMR 9017-CIIL-Center for Infection and Immunity of Lille, 59000 Lille, France; (H.M.); (V.P.)
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22
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Djemal R, Bradai M, Amor F, Hanin M, Ebel C. Wheat type one protein phosphatase promotes salt and osmotic stress tolerance in arabidopsis via auxin-mediated remodelling of the root system. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2023; 201:107832. [PMID: 37327648 DOI: 10.1016/j.plaphy.2023.107832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 05/31/2023] [Accepted: 06/09/2023] [Indexed: 06/18/2023]
Abstract
The control of optimal root growth and plant stress responses depends largely on a variety of phytohormones among which auxin and brassinosteroids (BRs) are the most influential. We have previously reported that the durum wheat type 1 protein phosphatase TdPP1 participates in the control of root growth by modulating BR signaling. In this study, we pursue our understanding of how TdPP1 fulfills this regulatory function on root growth by evaluating the physiological and molecular responses of Arabidopsis TdPP1 over-expressing lines to abiotic stresses. Our results showed that when exposed to 300 mM Mannitol or 100 mM NaCl, the seedlings of TdPP1 over-expressors exhibit modified root architecture with higher lateral root density, and longer root hairs concomitant with a lower inhibition of the primary root growth. These lines also exhibit faster gravitropic response and a decrease in primary root growth inhibition when exposed to high concentrations of exogenous IAA. On another hand, a cross between TdPP1 overexpressors and DR5:GUS marker line was performed to monitor auxin accumulation in roots. Remarkably, the TdPP1 overexpression resulted in an enhanced auxin gradient under salt stress with a higher accumulation in primary and lateral root tips. Moreover, TdPP1 transgenics exhibit a significant induction of a subset of auxin-responsive genes under salt stress conditions. Therefore, our results reveal a role of PP1 in enhancing auxin signaling to help shape greater root plasticity thus improving plant stress resilience.
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Affiliation(s)
- Rania Djemal
- Plant Physiology and Functional Genomics Research Unit, Higher Institute of Biotechnology, University of Sfax, BP "1175", 3038, Sfax, Tunisia
| | - Mariem Bradai
- Plant Physiology and Functional Genomics Research Unit, Higher Institute of Biotechnology, University of Sfax, BP "1175", 3038, Sfax, Tunisia
| | - Fatma Amor
- Plant Physiology and Functional Genomics Research Unit, Higher Institute of Biotechnology, University of Sfax, BP "1175", 3038, Sfax, Tunisia
| | - Moez Hanin
- Plant Physiology and Functional Genomics Research Unit, Higher Institute of Biotechnology, University of Sfax, BP "1175", 3038, Sfax, Tunisia
| | - Chantal Ebel
- Plant Physiology and Functional Genomics Research Unit, Higher Institute of Biotechnology, University of Sfax, BP "1175", 3038, Sfax, Tunisia.
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23
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Ahmad A, Tigabu B, Ivanov A, Jerebtsova M, Ammosova T, Ramanathan P, Kumari N, Brantner CA, Pietzsch CA, Abdullah G, Popratiloff A, Widen S, Bukreyev A, Nekhai S. Ebola Virus NP Binding to Host Protein Phosphatase-1 Regulates Capsid Formation. RESEARCH SQUARE 2023:rs.3.rs-2963943. [PMID: 37333330 PMCID: PMC10274954 DOI: 10.21203/rs.3.rs-2963943/v1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
The Ebola virus (EBOV) transcriptional regulation involves host protein phosphatases PP1 and PP2A, which dephosphorylate the transcriptional cofactor of EBOV polymerase VP30. The 1E7-03 compound, which targets PP1, induces VP30 phosphorylation and inhibits EBOV infection. This study aimed to investigate the role of PP1 in EBOV replication. When EBOV-infected cells were continuously treated with 1E7-03, the NP E619K mutation was selected. This mutation moderately reduced EBOV minigenome transcription, which was restored by the treatment with 1E7-03. Formation of EBOV capsids, when NP was co-expressed with VP24 and VP35, was impaired with NPE 619K. Treatment with 1E7-03 restored capsid formation by NP E619K mutation, but inhibited capsids formed by WT NP. The dimerization of NP E619K, tested in a split NanoBiT assay, was significantly decreased (~ 15-fold) compared to WT NP. NP E619K bound more efficiently to PP1 (~ 3-fold) but not B56 subunit of PP2A or VP30. Cross-linking and co-immunoprecipitation experiments showed fewer monomers and dimers for NP E619K which were increased with 1E7-03 treatment. NP E619K showed increased co-localization with PP1α compared to WT NP. Mutations of potential PP1 binding sites and NP deletions disrupted its interaction with PP1. Collectively, our findings suggest that PP1 binding to the NP regulates NP dimerization and capsid formation, and that NP E619K mutation, which has the enhanced PP1 binding, disrupts these processes. Our results point to a new role for PP1 in EBOV replication in which NP binding to PP1 may facilitate viral transcription by delaying capsid formation and EBOV replication.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | - Steve Widen
- UTMB: The University of Texas Medical Branch at Galveston
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Patil RS, Kovacs-Kasa A, Gorshkov BA, Fulton DJR, Su Y, Batori RK, Verin AD. Serine/Threonine Protein Phosphatases 1 and 2A in Lung Endothelial Barrier Regulation. Biomedicines 2023; 11:1638. [PMID: 37371733 PMCID: PMC10296329 DOI: 10.3390/biomedicines11061638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 05/28/2023] [Accepted: 06/02/2023] [Indexed: 06/29/2023] Open
Abstract
Vascular barrier dysfunction is characterized by increased permeability and inflammation of endothelial cells (ECs), which are prominent features of acute lung injury (ALI), acute respiratory distress syndrome (ARDS), and sepsis, and a major complication of the SARS-CoV-2 infection and COVID-19. Functional impairment of the EC barrier and accompanying inflammation arises due to microbial toxins and from white blood cells of the lung as part of a defensive action against pathogens, ischemia-reperfusion or blood product transfusions, and aspiration syndromes-based injury. A loss of barrier function results in the excessive movement of fluid and macromolecules from the vasculature into the interstitium and alveolae resulting in pulmonary edema and collapse of the architecture and function of the lungs, and eventually culminates in respiratory failure. Therefore, EC barrier integrity, which is heavily dependent on cytoskeletal elements (mainly actin filaments, microtubules (MTs), cell-matrix focal adhesions, and intercellular junctions) to maintain cellular contacts, is a critical requirement for the preservation of lung function. EC cytoskeletal remodeling is regulated, at least in part, by Ser/Thr phosphorylation/dephosphorylation of key cytoskeletal proteins. While a large body of literature describes the role of phosphorylation of cytoskeletal proteins on Ser/Thr residues in the context of EC barrier regulation, the role of Ser/Thr dephosphorylation catalyzed by Ser/Thr protein phosphatases (PPases) in EC barrier regulation is less documented. Ser/Thr PPases have been proposed to act as a counter-regulatory mechanism that preserves the EC barrier and opposes EC contraction. Despite the importance of PPases, our knowledge of the catalytic and regulatory subunits involved, as well as their cellular targets, is limited and under-appreciated. Therefore, the goal of this review is to discuss the role of Ser/Thr PPases in the regulation of lung EC cytoskeleton and permeability with special emphasis on the role of protein phosphatase 1 (PP1) and protein phosphatase 2A (PP2A) as major mammalian Ser/Thr PPases. Importantly, we integrate the role of PPases with the structural dynamics of the cytoskeleton and signaling cascades that regulate endothelial cell permeability and inflammation.
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Affiliation(s)
- Rahul S. Patil
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Anita Kovacs-Kasa
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Boris A. Gorshkov
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - David J. R. Fulton
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
- Department of Pharmacology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Yunchao Su
- Department of Pharmacology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Robert K. Batori
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Alexander D. Verin
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
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Christensen KR, Combs B, Richards C, Grabinski T, Alhadidy MM, Kanaan NM. Phosphomimetics at Ser199/Ser202/Thr205 in Tau Impairs Axonal Transport in Rat Hippocampal Neurons. Mol Neurobiol 2023; 60:3423-3438. [PMID: 36859689 PMCID: PMC10122714 DOI: 10.1007/s12035-023-03281-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 02/16/2023] [Indexed: 03/03/2023]
Abstract
Our understanding of the biological functions of the tau protein now includes its role as a scaffolding protein involved in signaling regulation, which also has implications for tau-mediated dysfunction and degeneration in Alzheimer's disease and other tauopathies. Recently, we found that pseudophosphorylation at sites linked to the pathology-associated AT8 phosphoepitope of tau disrupts normal fast axonal transport through a protein phosphatase 1 (PP1)-dependent pathway in squid axoplasm. Activation of the pathway and the resulting transport deficits required tau's N-terminal phosphatase-activating domain (PAD) and PP1 but the connection between tau and PP1 was not well defined. Here, we studied functional interactions between tau and PP1 isoforms and their effects on axonal transport in mammalian neurons. First, we found that wild-type tau interacted with PP1α and PP1γ primarily through its microtubule-binding repeat domain. Pseudophosphorylation of tau at S199/S202/T205 (psTau) increased PAD exposure, enhanced interactions with PP1γ, and increased active PP1γ levels in mammalian cells. Expression of psTau also significantly impaired axonal transport in primary rat hippocampal neurons. Deletion of PAD in psTau significantly reduced the interaction with PP1γ, eliminated increases of active PP1γ levels, and rescued axonal transport impairment in neurons. These data suggest that a functional consequence of phosphorylation within S199-T205 in tau, which occurs in AD and several other tauopathies, may be aberrant interaction with and activation of PP1γ and subsequent axonal transport disruption in a PAD-dependent fashion.
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Affiliation(s)
- Kyle R Christensen
- Department of Translational Neuroscience, Michigan State University, 400 Monroe Ave NW, Grand Rapids, MI, 49503, USA
- Neuroscience Program, Michigan State University, East Lansing, MI, 48824, USA
| | - Benjamin Combs
- Department of Translational Neuroscience, Michigan State University, 400 Monroe Ave NW, Grand Rapids, MI, 49503, USA
| | - Collin Richards
- Department of Translational Neuroscience, Michigan State University, 400 Monroe Ave NW, Grand Rapids, MI, 49503, USA
| | - Tessa Grabinski
- Department of Translational Neuroscience, Michigan State University, 400 Monroe Ave NW, Grand Rapids, MI, 49503, USA
| | - Mohammed M Alhadidy
- Department of Translational Neuroscience, Michigan State University, 400 Monroe Ave NW, Grand Rapids, MI, 49503, USA
- Neuroscience Program, Michigan State University, East Lansing, MI, 48824, USA
| | - Nicholas M Kanaan
- Department of Translational Neuroscience, Michigan State University, 400 Monroe Ave NW, Grand Rapids, MI, 49503, USA.
- Neuroscience Program, Michigan State University, East Lansing, MI, 48824, USA.
- Hauenstein Neuroscience Center, Mercy Health Saint Mary's, Grand Rapids, MI, 49503, USA.
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Wang B, He W, Huang M, Feng J, Li Y, Yu L, Wang Y, Zhou D, Meng C, Cheng D, Tang N, Song B, Chen H. Ralstonia solanacearum type III effector RipAS associates with potato type one protein phosphatase StTOPP6 to promote bacterial wilt. HORTICULTURE RESEARCH 2023; 10:uhad087. [PMID: 37334181 PMCID: PMC10273071 DOI: 10.1093/hr/uhad087] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Accepted: 04/24/2023] [Indexed: 06/20/2023]
Abstract
The bacterial pathogen Ralstonia solanacearum (R. solanacearum) delivered type III secretion effectors to inhibit the immune system and cause bacterial wilt on potato. Protein phosphatases are key regulators in plant immunity, which pathogens can manipulate to alter host processes. Here, we show that a type III effector RipAS can reduce the nucleolar accumulation of a type one protein phosphatase (PP1) StTOPP6 to promote bacterial wilt. StTOPP6 was used as bait in the Yeast two-Hybrid (Y2H) assay and acquired an effector RipAS that interacts with it. RipAS was characterized as a virulence effector to contribute to R. solanacearum infection, and stable expression of RipAS in potato impaired plant resistance against R. solanacearum. Overexpression of StTOPP6 showed enhanced disease symptoms when inoculated with wild strain UW551 but not the ripAS deletion mutant, indicating that the expression of StTOPP6 facilitates the virulence of RipAS. RipAS reduced the nucleolar accumulation of StTOPP6, which occurred during R. solanacearum infection. Moreover, the association also widely existed between other PP1s and RipAS. We argue that RipAS is a virulence effector associated with PP1s to promote bacterial wilt.
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Affiliation(s)
- Bingsen Wang
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan 430070, China
- Key Laboratory of Potato Biology and Biotechnology (HZAU), Ministry of Agriculture and Rural Affairs, Wuhan 430070, China
- Potato Engineering and Technology Research Center of Hubei Province, Huazhong Agricultural University, Wuhan 430070, China
- College of Horticulture and Forestry Science, Huazhong Agricultural University, Wuhan 430070, China
| | - Wenfeng He
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan 430070, China
- Key Laboratory of Potato Biology and Biotechnology (HZAU), Ministry of Agriculture and Rural Affairs, Wuhan 430070, China
- Potato Engineering and Technology Research Center of Hubei Province, Huazhong Agricultural University, Wuhan 430070, China
- College of Horticulture and Forestry Science, Huazhong Agricultural University, Wuhan 430070, China
| | - Mengshu Huang
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan 430070, China
- Key Laboratory of Potato Biology and Biotechnology (HZAU), Ministry of Agriculture and Rural Affairs, Wuhan 430070, China
- Potato Engineering and Technology Research Center of Hubei Province, Huazhong Agricultural University, Wuhan 430070, China
- College of Horticulture and Forestry Science, Huazhong Agricultural University, Wuhan 430070, China
| | - Jiachen Feng
- State Key Laboratory of Crop Stress Adaptation and Improvement, Henan University, Kaifeng 475001, China
| | - Yanping Li
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan 430070, China
- Key Laboratory of Potato Biology and Biotechnology (HZAU), Ministry of Agriculture and Rural Affairs, Wuhan 430070, China
- Potato Engineering and Technology Research Center of Hubei Province, Huazhong Agricultural University, Wuhan 430070, China
- College of Horticulture and Forestry Science, Huazhong Agricultural University, Wuhan 430070, China
| | - Liu Yu
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan 430070, China
- Key Laboratory of Potato Biology and Biotechnology (HZAU), Ministry of Agriculture and Rural Affairs, Wuhan 430070, China
- Potato Engineering and Technology Research Center of Hubei Province, Huazhong Agricultural University, Wuhan 430070, China
- College of Horticulture and Forestry Science, Huazhong Agricultural University, Wuhan 430070, China
| | - Yuqi Wang
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan 430070, China
- Key Laboratory of Potato Biology and Biotechnology (HZAU), Ministry of Agriculture and Rural Affairs, Wuhan 430070, China
- Potato Engineering and Technology Research Center of Hubei Province, Huazhong Agricultural University, Wuhan 430070, China
- College of Horticulture and Forestry Science, Huazhong Agricultural University, Wuhan 430070, China
| | - Dan Zhou
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan 430070, China
- Key Laboratory of Potato Biology and Biotechnology (HZAU), Ministry of Agriculture and Rural Affairs, Wuhan 430070, China
- Potato Engineering and Technology Research Center of Hubei Province, Huazhong Agricultural University, Wuhan 430070, China
- College of Horticulture and Forestry Science, Huazhong Agricultural University, Wuhan 430070, China
| | - Chengzhen Meng
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan 430070, China
- Key Laboratory of Potato Biology and Biotechnology (HZAU), Ministry of Agriculture and Rural Affairs, Wuhan 430070, China
- Potato Engineering and Technology Research Center of Hubei Province, Huazhong Agricultural University, Wuhan 430070, China
- College of Horticulture and Forestry Science, Huazhong Agricultural University, Wuhan 430070, China
| | - Dong Cheng
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan 430070, China
- Key Laboratory of Potato Biology and Biotechnology (HZAU), Ministry of Agriculture and Rural Affairs, Wuhan 430070, China
- Potato Engineering and Technology Research Center of Hubei Province, Huazhong Agricultural University, Wuhan 430070, China
- College of Horticulture and Forestry Science, Huazhong Agricultural University, Wuhan 430070, China
| | - Ning Tang
- State Key Laboratory of Crop Stress Adaptation and Improvement, Henan University, Kaifeng 475001, China
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Alba Posse EJ, González C, Carriquiriborde P, Nadra A, Gasulla J. Optimization and validation of a protein phosphatase inhibition assay for accessible microcystin detection. Talanta 2023; 255:124174. [PMID: 36608426 DOI: 10.1016/j.talanta.2022.124174] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 11/28/2022] [Accepted: 12/04/2022] [Indexed: 12/27/2022]
Abstract
The presence of cyanobacterial toxins in freshwater constitutes an increasing public health concern, especially affecting developing countries where the high cost of available methods makes monitoring programs difficult. The phosphatase inhibition assay (PPIA) is a sensitive method with low instrument requirements that allows the quantification of the most frequent cyanotoxins, microcystins (MCs). In this work, we implemented a PPIA, starting from Protein Phosphatase 1 (PP1) expression up to the validation with samples of algal blooms from Argentina. To do this, we optimized the expression and lyophilization of PP1, and the assay conditions. Also, we included robustness and possible interference analysis. We evaluated the most widely used cyanobacterial lysis methods and determined that heating for 15 min at 95 °C is simple and adequate for this assay. Then, we performed MC spikes recovery assays on water samples from three dams from Argentina, resulting in a recovery ranging from 77 to 115%. The limit of detection (LOD) was 0.4 μg/L and the linear range is 0.4 μg/L - 5 μg/L. Finally, we evaluated 65 environmental samples where MCs was measured by ELISA test containing from 0 μg/L to 625 μg/L. The PPIA showed excellent correlation (Pearson correlation coefficient = 0.967), no false negative and no false positives above the 1 μg/L WHO guideline (0.11 false positive rate). In conclusion, we optimized and validated a PPIA to be an effective and accessible alternative to available commercial tests.
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Affiliation(s)
- Ezequiel Jorge Alba Posse
- Facultad de Ciencias Exactas y Naturales, Departamento de Fisiología y Biología Molecular y Celular, Instituto de Biociencias, Biotecnología y Biología Traslacional (iB3), Universidad de Buenos Aires, Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Godoy Cruz 2290, C1425FQB Buenos Aires, Argentina
| | - Carolina González
- Facultad de Ciencias Exactas y Naturales, Departamento de Ecología, Genética y Evolución, Instituto IEGEBA (CONICET-UBA), Universidad de Buenos Aires, Argentina; Centro de investigaciones, Agua y Saneamientos Argentinos, CABA, Argentina
| | - Pedro Carriquiriborde
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Godoy Cruz 2290, C1425FQB Buenos Aires, Argentina; Centro de Investigaciones Del Medio Ambiente (CIM),Universidad Nacional de la Plata-CONICET, La Plata, Argentina
| | - Alejandro Nadra
- Facultad de Ciencias Exactas y Naturales, Departamento de Fisiología y Biología Molecular y Celular, Instituto de Biociencias, Biotecnología y Biología Traslacional (iB3), Universidad de Buenos Aires, Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Godoy Cruz 2290, C1425FQB Buenos Aires, Argentina
| | - Javier Gasulla
- Facultad de Ciencias Exactas y Naturales, Departamento de Fisiología y Biología Molecular y Celular, Instituto de Biociencias, Biotecnología y Biología Traslacional (iB3), Universidad de Buenos Aires, Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Godoy Cruz 2290, C1425FQB Buenos Aires, Argentina; Centro de Investigaciones Del Medio Ambiente (CIM),Universidad Nacional de la Plata-CONICET, La Plata, Argentina.
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Lin X, Ahmad A, Ivanov AI, Simhadri J, Wang S, Kumari N, Ammosova T, Nekhai S. HIV-1 Transcription Inhibitor 1E7-03 Decreases Nucleophosmin Phosphorylation. Mol Cell Proteomics 2023; 22:100488. [PMID: 36563749 PMCID: PMC9975258 DOI: 10.1016/j.mcpro.2022.100488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 12/07/2022] [Accepted: 12/18/2022] [Indexed: 12/25/2022] Open
Abstract
Transcription activation of latent human immunodeficiency virus-1 (HIV-1) occurs due to HIV-1 rebound, the interruption of combination antiretroviral therapy, or development of drug resistance. Thus, novel HIV-1 inhibitors, targeting HIV-1 transcription are needed. We previously developed an HIV-1 transcription inhibitor, 1E7-03, that binds to the noncatalytic RVxF-accommodating site of protein phosphatase 1 and inhibits HIV-1 replication in cultured cells and HIV-1-infected humanized mice by impeding protein phosphatase 1 interaction with HIV-1 Tat protein. However, host proteins and regulatory pathways targeted by 1E7-03 that contribute to its overall HIV-1 inhibitory activity remain to be identified. To address this issue, we performed label-free quantitative proteome and phosphoproteome analyses of noninfected and HIV-1-infected CEM T cells that were untreated or treated with 1E7-03. 1E7-03 significantly reprogramed the phosphorylation profile of proteins including PPARα/RXRα, TGF-β, and PKR pathways. Phosphorylation of nucleophosmin (NPM1) at Ser-125 residue in PPARα/RXRα pathway was significantly reduced (>20-fold, p = 1.37 × 10-9), followed by the reduced phosphorylation of transforming growth factor-beta 2 at Ser-46 (TGF-β2, >12-fold, p = 1.37 × 10-3). Downregulation of NPM1's Ser-125 phosphorylation was further confirmed using Western blot. Phosphorylation mimicking NPM1 S125D mutant activated Tat-induced HIV-1 transcription and exhibited enhanced NPM1-Tat interaction compared to NPM1 S125A mutant. Inhibition of Aurora A or Aurora B kinases that phosphorylate NPM1 on Ser-125 residue inhibited HIV-1, further supporting the role of NPM1 in HIV-1 infection. Taken together, 1E7-03 reprogrammed PPARα/RXRα and TGF-β pathways that contribute to the inhibition of HIV-1 transcription. Our findings suggest that NPM1 phosphorylation is a plausible target for HIV-1 transcription inhibition.
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Key Words
- actn4, alpha-actinin-1
- asl, argininosuccinate lyase
- aspm, abnormal spindle-like microcephaly-associated protein
- cart, combination antiretroviral therapy
- cdk2, cell cycle-dependent kinase 2
- ck2, casein kinase 2
- dmso, dimethyl sulfoxide
- egln1, egl-9 family hypoxia inducible factor 1
- erk/p38, extracellular signal-regulated kinase p38
- fa, formic acid
- gadd34, growth arrest and dna damage-inducible protein
- hif-1α, hypoxia-inducible factor 1α
- hiv-1 vif protein, viral infectivity factor, an hiv-1 accessory protein
- hiv-1, human immunodeficiency virus-1
- hsp90, heat shock protein 90
- ipa, ingenuity pathway analysis
- lc-ft/ms, tandem liquid chromatography-fourier transform mass spectrometry
- mapk, mitogen-activated protein kinase
- map3k4, mitogen-activated protein kinase kinase kinase 4
- mita, mediator of interferon response factor 3 activation
- nfat, nuclear factor of activated t cells
- nf-κb, nuclear factor kappa-light-chain-enhancer of activated b cell
- npm1, nucleophosmin
- oa, okadaic acid
- pi3k/akt, phosphoinositide 3-kinase/ ak strain transforming or protein kinase b
- pp, protein phosphatase
- pparα/rxrα, peroxisome proliferator-activated receptor α/ retinoid x receptor α
- ptm, posttranslational modification
- rnr2, ribonucleotide reductase 2
- rt, reverse transcription
- samhd1, sam domain and hd domain-containing protein 1
- smad7, mothers against decapentaplegic homolog 7
- stat5, signal transducer and activator of transcription 5 taf4
- taf4, transcription factor tfiid subunit tata-box-binding protein (tbp)-associated factor 4
- tgf-β2, transforming growth factor-beta
- tp53, tumor protein p53
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Affiliation(s)
- Xionghao Lin
- Center for Sickle Cell Disease, College of Medicine, Howard University, Washington, District of Columbia, USA; College of Dentistry, Howard University, Washington, District of Columbia, USA
| | - Asrar Ahmad
- Center for Sickle Cell Disease, College of Medicine, Howard University, Washington, District of Columbia, USA
| | - Andrey I Ivanov
- Center for Sickle Cell Disease, College of Medicine, Howard University, Washington, District of Columbia, USA
| | - Jyothirmai Simhadri
- Center for Sickle Cell Disease, College of Medicine, Howard University, Washington, District of Columbia, USA
| | - Songping Wang
- Center for Sickle Cell Disease, College of Medicine, Howard University, Washington, District of Columbia, USA
| | - Namita Kumari
- Center for Sickle Cell Disease, College of Medicine, Howard University, Washington, District of Columbia, USA; Department of Microbiology, College of Medicine, Howard University, Washington, District of Columbia, USA
| | - Tatiana Ammosova
- Center for Sickle Cell Disease, College of Medicine, Howard University, Washington, District of Columbia, USA; Department of Medicine, College of Medicine, Howard University, Washington, District of Columbia, USA
| | - Sergei Nekhai
- Center for Sickle Cell Disease, College of Medicine, Howard University, Washington, District of Columbia, USA; Department of Microbiology, College of Medicine, Howard University, Washington, District of Columbia, USA; Department of Medicine, College of Medicine, Howard University, Washington, District of Columbia, USA.
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Abstract
Phosphatases and kinases maintain an equilibrium of dephosphorylated and phosphorylated proteins, respectively, that are required for critical cellular functions. Imbalance in this equilibrium or irregularity in their function causes unfavorable cellular effects that have been implicated in the development of numerous diseases. Protein tyrosine phosphatases (PTPs) catalyze the dephosphorylation of protein substrates on tyrosine residues, and their involvement in cell signaling and diseases such as cancer and inflammatory and metabolic diseases has made them attractive therapeutic targets. However, PTPs have proved challenging in therapeutics development, garnering them the unfavorable reputation of being undruggable. Nonetheless, great strides have been made toward the inhibition of PTPs over the past decade. Here, we discuss the advancement in small-molecule inhibition for the PTP subfamily known as the mitogen-activated protein kinase (MAPK) phosphatases (MKPs). We review strategies and inhibitor discovery tools that have proven successful for small-molecule inhibition of the MKPs and discuss what the future of MKP inhibition potentially might yield.
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Affiliation(s)
- Shanelle R Shillingford
- Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut, USA;
- Department of Chemistry, Yale University, New Haven, Connecticut, USA
| | - Anton M Bennett
- Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut, USA;
- Yale Center for Molecular and Systems Metabolism, Yale University School of Medicine, New Haven, Connecticut, USA
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PARK NORAJEEYOUNG, CHOI YESEUL, LEE DONGHYEON, PARK JIYOUNG, KIM JONGMI, LEE YOONHEE, HONG DAEGY, CHONG GUNOH, HAN HYUNGSOO. Transcriptomic Network Analysis Using Exfoliative Cervical Cells Could Discriminate a Potential Risk of Progression to Cancer in HPV-related Cervical Lesions: A Pilot Study. Cancer Genomics Proteomics 2023; 20:75-87. [PMID: 36581343 PMCID: PMC9806671 DOI: 10.21873/cgp.20366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 11/01/2022] [Accepted: 11/22/2022] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND/AIM Cervical cancer is the fourth most common type of cancer in women worldwide and it is a major cause of cancer-related deaths in developing countries. Despite the marked reduction observed in the rates of the disease as a result of screening programs, it is necessary to develop robust biomarkers that can detect the neoplastic progression early in HPV-related cervical lesions. MATERIALS AND METHODS We performed comparative mRNA sequencing from exfoliative cervical cytology samples from nine Korean women using the Illumina NovaSeq6000 platform. Each pathological tissue was matched to the corresponding cytological sample. The pathologic diagnosis was scrutinized with ancillary immunohistochemistry and was considered a confirmative (endpoint) diagnosis. The pathological diagnoses consisted of three cases of chronic cervicitis, 2 high-grade squamous intraepithelial lesions (HSILs), 2 squamous cell carcinomas in situ (CIS), and 2 invasive squamous cell carcinomas (SQCCs), respectively. Using bioinformatic analyses, differentially expressed genes (DEGs; fold change ≥1.5; p<0.05) were applied for Gene Ontology (GO), Gene Set Enrichment Analysis (GSEA), and protein-protein interaction (PPI) networks. RESULTS From a total of 55,882 genes, 438 DEGs were pinpointed; 282 genes were up-regulated and 156 genes down-regulated. These transcriptomic profiles were clearly divided into neoplastic (HSIL, CIS, and SQCC; ≥HSILs) and non-neoplastic lesions. The up-regulated DEGs were HIF-1a, EDN1, PIK3R3, PPP1CA and AKR1C1. GO, GSEA, and PPI network analyses showed marked associations with metabolism, proteolysis, or proteoglycan process pathways in cervical carcinogenesis. CONCLUSION The transcriptomic analysis using exfoliative cervical cells was more likely representative of its corresponding histopathological diagnosis, thus emphasizing its potential utility in clinical practice. This study provides comprehensive transcriptomic network analyses for robust biomarkers that might present a high potential risk of progression to cancer in the exfoliative cervical cytology; our findings support their clinical utility for improved cervical cancer screening.
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Affiliation(s)
- NORA JEE-YOUNG PARK
- Department of Pathology, School of Medicine, Kyungpook National University, Daegu, Republic of Korea,Department of Pathology, Kyungpook National University Chilgok Hospital, Daegu, Republic of Korea,Clinical Omics Research Center, School of Medicine, Kyungpook National University, Daegu, Republic of Korea,KNU Convergence Educational Program of Biomedical Sciences for Creative Future Talents, Kyungpook National University, Daegu, Republic of Korea
| | - YESEUL CHOI
- Department of Biomedical Science, Graduate School, Kyungpook National University, Daegu, Republic of Korea,BK21 Four Program, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
| | - DONGHYEON LEE
- Department of Biomedical Science, Graduate School, Kyungpook National University, Daegu, Republic of Korea,BK21 Four Program, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
| | - JI YOUNG PARK
- Department of Pathology, School of Medicine, Kyungpook National University, Daegu, Republic of Korea,Department of Pathology, Kyungpook National University Chilgok Hospital, Daegu, Republic of Korea
| | - JONG MI KIM
- Department of Obstetrics and Gynecology, School of Medicine, Kyungpook National University, Daegu, Republic of Korea,Department of Obstetrics and Gynecology, Kyungpook National University Chilgok Hospital, Daegu, Republic of Korea
| | - YOON HEE LEE
- Department of Obstetrics and Gynecology, School of Medicine, Kyungpook National University, Daegu, Republic of Korea,Department of Obstetrics and Gynecology, Kyungpook National University Chilgok Hospital, Daegu, Republic of Korea
| | - DAE GY HONG
- Department of Obstetrics and Gynecology, School of Medicine, Kyungpook National University, Daegu, Republic of Korea,Department of Obstetrics and Gynecology, Kyungpook National University Chilgok Hospital, Daegu, Republic of Korea
| | - GUN OH CHONG
- Clinical Omics Research Center, School of Medicine, Kyungpook National University, Daegu, Republic of Korea,KNU Convergence Educational Program of Biomedical Sciences for Creative Future Talents, Kyungpook National University, Daegu, Republic of Korea,Department of Obstetrics and Gynecology, School of Medicine, Kyungpook National University, Daegu, Republic of Korea,Department of Obstetrics and Gynecology, Kyungpook National University Chilgok Hospital, Daegu, Republic of Korea
| | - HYUNG SOO HAN
- Clinical Omics Research Center, School of Medicine, Kyungpook National University, Daegu, Republic of Korea,KNU Convergence Educational Program of Biomedical Sciences for Creative Future Talents, Kyungpook National University, Daegu, Republic of Korea,Department of Physiology, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
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Kuroiwa M, Shuto T, Nagai T, Amano M, Kaibuchi K, Nairn AC, Nishi A. DARPP-32/protein phosphatase 1 regulates Rasgrp2 as a novel component of dopamine D1 receptor signaling in striatum. Neurochem Int 2023; 162:105438. [PMID: 36351540 DOI: 10.1016/j.neuint.2022.105438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 10/14/2022] [Accepted: 11/01/2022] [Indexed: 11/09/2022]
Abstract
Dopamine regulates psychomotor function by D1 receptor/PKA-dependent phosphorylation of DARPP-32. DARPP-32, phosphorylated at Thr34 by PKA, inhibits protein phosphatase 1 (PP1), and amplifies the phosphorylation of other PKA/PP1 substrates following D1 receptor activation. In addition to the D1 receptor/PKA/DARPP-32 signaling pathway, D1 receptor stimulation is known to activate Rap1/ERK signaling. Rap1 activation is mediated through the phosphorylation of Rasgrp2 (guanine nucleotide exchange factor; activation) and Rap1gap (GTPase-activating protein; inhibition) by PKA. In this study, we investigated the role of PP1 inhibition by phospho-Thr34 DARPP-32 in the D1 receptor-induced phosphorylation of Rasgrp2 and Rap1gap at PKA sites. The analyses in striatal and NAc slices from wild-type and DARPP-32 knockout mice revealed that the phosphorylation of Rasgrp2 at Ser116/Ser117 and Ser586, but not of Rasgrp2 at Ser554 or Rap1gap at Ser441 or Ser499 induced by a D1 receptor agonist, is under the control of the DARPP-32/PP1. The results were supported by pharmacological analyses using a selective PP1 inhibitor, tautomycetin. In addition, analyses using a PP1 and PP2A inhibitor, okadaic acid, revealed that all sites of Rasgrp2 and Rap1gap were regulated by PP2A. Thus, the interactive machinery of DARPP-32/PP1 may contribute to efficient D1 receptor signaling via Rasgrp2/Rap1 in the striatum.
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Affiliation(s)
- Mahomi Kuroiwa
- Department of Pharmacology, Kurume University School of Medicine, Kurume, Fukuoka, 830-0011, Japan
| | - Takahide Shuto
- Department of Pharmacology, Kurume University School of Medicine, Kurume, Fukuoka, 830-0011, Japan
| | - Taku Nagai
- Division of Behavioral Neuropharmacology, International Center for Brain Science, Fujita Health University, Toyoake, Aichi, 470-1192, Japan
| | - Mutsuki Amano
- Department of Cell Pharmacology, Graduate School of Medicine, Nagoya University, Nagoya, Aichi, 466-8550, Japan
| | - Kozo Kaibuchi
- Department of Cell Pharmacology, Graduate School of Medicine, Nagoya University, Nagoya, Aichi, 466-8550, Japan; Division of Cell Biology, International Center for Brain Science, Fujita Health University, Toyoake, Aichi, 470-1192, Japan
| | - Angus C Nairn
- Department of Psychiatry, Yale School of Medicine, Connecticut Mental Health Center, New Haven, CT, 06519, United States
| | - Akinori Nishi
- Department of Pharmacology, Kurume University School of Medicine, Kurume, Fukuoka, 830-0011, Japan.
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The ribosomal RNA processing 1B:protein phosphatase 1 holoenzyme reveals non-canonical PP1 interaction motifs. Cell Rep 2022; 41:111726. [PMID: 36450254 PMCID: PMC9813921 DOI: 10.1016/j.celrep.2022.111726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 09/20/2022] [Accepted: 11/03/2022] [Indexed: 12/03/2022] Open
Abstract
The serine/threonine protein phosphatase 1 (PP1) dephosphorylates hundreds of substrates by associating with >200 regulatory proteins to form specific holoenzymes. The major PP1 targeting protein in the nucleolus is RRP1B (ribosomal RNA processing 1B). In addition to selectively recruiting PP1β/PP1γ to the nucleolus, RRP1B also has a key role in ribosome biogenesis, among other functions. How RRP1B binds PP1 and regulates nucleolar phosphorylation signaling is not yet known. Here, we show that RRP1B recruits PP1 via established (RVxF/SILK/ΦΦ) and non-canonical motifs. These atypical interaction sites, the PP1β/γ specificity, and N-terminal AF-binding pockets rely on hydrophobic interactions that contribute to binding and, via phosphorylation, regulate complex formation. This work advances our understanding of PP1 isoform selectivity, reveals key roles of N-terminal PP1 residues in regulator binding, and suggests that additional PP1 interaction sites have yet to be identified, all of which are necessary for a systems biology understanding of PP1 function.
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Benedyk TH, Connor V, Caroe ER, Shamin M, Svergun DI, Deane JE, Jeffries CM, Crump CM, Graham SC. Herpes simplex virus 1 protein pUL21 alters ceramide metabolism by activating the interorganelle transport protein CERT. J Biol Chem 2022; 298:102589. [PMID: 36243114 PMCID: PMC9668737 DOI: 10.1016/j.jbc.2022.102589] [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: 07/20/2022] [Revised: 10/04/2022] [Accepted: 10/05/2022] [Indexed: 11/06/2022] Open
Abstract
Herpes simplex virus (HSV)-1 dramatically alters the architecture and protein composition of cellular membranes during infection, but its effects upon membrane lipid composition remain unclear. HSV-1 pUL21 is a virus-encoded protein phosphatase adaptor that promotes dephosphorylation of multiple cellular and virus proteins, including the cellular ceramide (Cer) transport protein CERT. CERT mediates nonvesicular Cer transport from the endoplasmic reticulum to the trans-Golgi network, whereupon Cer is converted to sphingomyelin (SM) and other sphingolipids that play important roles in cellular proliferation, signaling, and membrane trafficking. Here, we use click chemistry to profile the kinetics of sphingolipid metabolism, showing that pUL21-mediated dephosphorylation activates CERT and accelerates Cer-to-SM conversion. Purified pUL21 and full-length CERT interact with submicromolar affinity, and we solve the solution structure of the pUL21 C-terminal domain in complex with the CERT Pleckstrin homology and steroidogenic acute regulatory-related lipid transfer domains using small-angle X-ray scattering. We identify a single amino acid mutation on the surface of pUL21 that disrupts CERT binding in vitro and in cultured cells. This residue is highly conserved across the genus Simplexvirus. In addition, we identify a pUL21 residue essential for binding to HSV-1 pUL16. Sphingolipid profiling demonstrates that Cer-to-SM conversion is severely diminished in the context of HSV-1 infection, a defect that is compounded when infecting with a virus encoding the mutated form of pUL21 that lacks the ability to activate CERT. However, virus replication and spread in cultured keratinocytes or epithelial cells is not significantly altered when pUL21-mediated CERT dephosphorylation is abolished. Collectively, we demonstrate that HSV-1 modifies sphingolipid metabolism via specific protein-protein interactions.
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Affiliation(s)
| | - Viv Connor
- Department of Pathology, University of Cambridge, Cambridge, UK
| | - Eve R Caroe
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
| | - Maria Shamin
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
| | - Dmitri I Svergun
- European Molecular Biology Laboratory (EMBL) Hamburg Site, Hamburg, Germany
| | - Janet E Deane
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
| | - Cy M Jeffries
- European Molecular Biology Laboratory (EMBL) Hamburg Site, Hamburg, Germany
| | - Colin M Crump
- Department of Pathology, University of Cambridge, Cambridge, UK
| | - Stephen C Graham
- Department of Pathology, University of Cambridge, Cambridge, UK.
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34
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Kokot T, Köhn M. Emerging insights into serine/threonine-specific phosphoprotein phosphatase function and selectivity. J Cell Sci 2022; 135:277104. [DOI: 10.1242/jcs.259618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
ABSTRACT
Protein phosphorylation on serine and threonine residues is a widely distributed post-translational modification on proteins that acts to regulate their function. Phosphoprotein phosphatases (PPPs) contribute significantly to a plethora of cellular functions through the accurate dephosphorylation of phosphorylated residues. Most PPPs accomplish their purpose through the formation of complex holoenzymes composed of a catalytic subunit with various regulatory subunits. PPP holoenzymes then bind and dephosphorylate substrates in a highly specific manner. Despite the high prevalence of PPPs and their important role for cellular function, their mechanisms of action in the cell are still not well understood. Nevertheless, substantial experimental advancements in (phospho-)proteomics, structural and computational biology have contributed significantly to a better understanding of PPP biology in recent years. This Review focuses on recent approaches and provides an overview of substantial new insights into the complex mechanism of PPP holoenzyme regulation and substrate selectivity.
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Affiliation(s)
- Thomas Kokot
- Signalling Research Centres BIOSS and CIBSS, University of Freiburg 1 , Freiburg 79104 , Germany
- University of Freiburg, 2 Faculty of Biology , Freiburg 79104 , Germany
| | - Maja Köhn
- Signalling Research Centres BIOSS and CIBSS, University of Freiburg 1 , Freiburg 79104 , Germany
- University of Freiburg, 2 Faculty of Biology , Freiburg 79104 , Germany
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35
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Bonsor DA, Alexander P, Snead K, Hartig N, Drew M, Messing S, Finci LI, Nissley DV, McCormick F, Esposito D, Rodriguez-Viciana P, Stephen AG, Simanshu DK. Structure of the SHOC2-MRAS-PP1C complex provides insights into RAF activation and Noonan syndrome. Nat Struct Mol Biol 2022; 29:966-977. [PMID: 36175670 PMCID: PMC10365013 DOI: 10.1038/s41594-022-00841-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 08/12/2022] [Indexed: 11/08/2022]
Abstract
SHOC2 acts as a strong synthetic lethal interactor with MEK inhibitors in multiple KRAS cancer cell lines. SHOC2 forms a heterotrimeric complex with MRAS and PP1C that is essential for regulating RAF and MAPK-pathway activation by dephosphorylating a specific phosphoserine on RAF kinases. Here we present the high-resolution crystal structure of the SHOC2-MRAS-PP1C (SMP) complex and apo-SHOC2. Our structures reveal that SHOC2, MRAS, and PP1C form a stable ternary complex in which all three proteins synergistically interact with each other. Our results show that dephosphorylation of RAF substrates by PP1C is enhanced upon interacting with SHOC2 and MRAS. The SMP complex forms only when MRAS is in an active state and is dependent on SHOC2 functioning as a scaffolding protein in the complex by bringing PP1C and MRAS together. Our results provide structural insights into the role of the SMP complex in RAF activation and how mutations found in Noonan syndrome enhance complex formation, and reveal new avenues for therapeutic interventions.
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Affiliation(s)
- Daniel A Bonsor
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Patrick Alexander
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Kelly Snead
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Nicole Hartig
- UCL Cancer Institute, University College London, London, UK
| | - Matthew Drew
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Simon Messing
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Lorenzo I Finci
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Dwight V Nissley
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Frank McCormick
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
- University of California, San Francisco Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA, USA
| | - Dominic Esposito
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | | | - Andrew G Stephen
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Dhirendra K Simanshu
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA.
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36
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Acharya D, Reis R, Volcic M, Liu G, Wang MK, Chia BS, Nchioua R, Groß R, Münch J, Kirchhoff F, Sparrer KMJ, Gack MU. Actin cytoskeleton remodeling primes RIG-I-like receptor activation. Cell 2022; 185:3588-3602.e21. [PMID: 36113429 PMCID: PMC9680832 DOI: 10.1016/j.cell.2022.08.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Revised: 06/17/2022] [Accepted: 08/10/2022] [Indexed: 01/26/2023]
Abstract
The current dogma of RNA-mediated innate immunity is that sensing of immunostimulatory RNA ligands is sufficient for the activation of intracellular sensors and induction of interferon (IFN) responses. Here, we report that actin cytoskeleton disturbance primes RIG-I-like receptor (RLR) activation. Actin cytoskeleton rearrangement induced by virus infection or commonly used reagents to intracellularly deliver RNA triggers the relocalization of PPP1R12C, a regulatory subunit of the protein phosphatase-1 (PP1), from filamentous actin to cytoplasmic RLRs. This allows dephosphorylation-mediated RLR priming and, together with the RNA agonist, induces effective RLR downstream signaling. Genetic ablation of PPP1R12C impairs antiviral responses and enhances susceptibility to infection with several RNA viruses including SARS-CoV-2, influenza virus, picornavirus, and vesicular stomatitis virus. Our work identifies actin cytoskeleton disturbance as a priming signal for RLR-mediated innate immunity, which may open avenues for antiviral or adjuvant design.
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Affiliation(s)
- Dhiraj Acharya
- Florida Research and Innovation Center, Cleveland Clinic, Port Saint Lucie, FL 34987, USA; Department of Microbiology, The University of Chicago, Chicago, IL 60637, USA
| | - Rebecca Reis
- Department of Microbiology, The University of Chicago, Chicago, IL 60637, USA
| | - Meta Volcic
- Institute of Molecular Virology, Ulm University Medical Center, 89081 Ulm, Germany
| | - GuanQun Liu
- Florida Research and Innovation Center, Cleveland Clinic, Port Saint Lucie, FL 34987, USA; Department of Microbiology, The University of Chicago, Chicago, IL 60637, USA
| | - May K Wang
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Bing Shao Chia
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Rayhane Nchioua
- Institute of Molecular Virology, Ulm University Medical Center, 89081 Ulm, Germany
| | - Rüdiger Groß
- Institute of Molecular Virology, Ulm University Medical Center, 89081 Ulm, Germany
| | - Jan Münch
- Institute of Molecular Virology, Ulm University Medical Center, 89081 Ulm, Germany
| | - Frank Kirchhoff
- Institute of Molecular Virology, Ulm University Medical Center, 89081 Ulm, Germany
| | | | - Michaela U Gack
- Florida Research and Innovation Center, Cleveland Clinic, Port Saint Lucie, FL 34987, USA; Department of Microbiology, The University of Chicago, Chicago, IL 60637, USA.
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37
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Liau NPD, Johnson MC, Izadi S, Gerosa L, Hammel M, Bruning JM, Wendorff TJ, Phung W, Hymowitz SG, Sudhamsu J. Structural basis for SHOC2 modulation of RAS signalling. Nature 2022; 609:400-407. [PMID: 35768504 PMCID: PMC9452301 DOI: 10.1038/s41586-022-04838-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Accepted: 05/05/2022] [Indexed: 12/12/2022]
Abstract
The RAS-RAF pathway is one of the most commonly dysregulated in human cancers1-3. Despite decades of study, understanding of the molecular mechanisms underlying dimerization and activation4 of the kinase RAF remains limited. Recent structures of inactive RAF monomer5 and active RAF dimer5-8 bound to 14-3-39,10 have revealed the mechanisms by which 14-3-3 stabilizes both RAF conformations via specific phosphoserine residues. Prior to RAF dimerization, the protein phosphatase 1 catalytic subunit (PP1C) must dephosphorylate the N-terminal phosphoserine (NTpS) of RAF11 to relieve inhibition by 14-3-3, although PP1C in isolation lacks intrinsic substrate selectivity. SHOC2 is as an essential scaffolding protein that engages both PP1C and RAS to dephosphorylate RAF NTpS11-13, but the structure of SHOC2 and the architecture of the presumptive SHOC2-PP1C-RAS complex remain unknown. Here we present a cryo-electron microscopy structure of the SHOC2-PP1C-MRAS complex to an overall resolution of 3 Å, revealing a tripartite molecular architecture in which a crescent-shaped SHOC2 acts as a cradle and brings together PP1C and MRAS. Our work demonstrates the GTP dependence of multiple RAS isoforms for complex formation, delineates the RAS-isoform preference for complex assembly, and uncovers how the SHOC2 scaffold and RAS collectively drive specificity of PP1C for RAF NTpS. Our data indicate that disease-relevant mutations affect complex assembly, reveal the simultaneous requirement of two RAS molecules for RAF activation, and establish rational avenues for discovery of new classes of inhibitors to target this pathway.
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Affiliation(s)
- Nicholas P D Liau
- Department of Structural Biology, Genentech, South San Francisco, CA, USA
| | - Matthew C Johnson
- Department of Structural Biology, Genentech, South San Francisco, CA, USA
| | - Saeed Izadi
- Pharmaceutical Development, Genentech, South San Francisco, CA, USA
| | - Luca Gerosa
- Department of Bioinformatics and Computational Biology, Genentech, South San Francisco, CA, USA
| | - Michal Hammel
- Physical Bioscience Division, Lawrence Berkeley National Labs, Berkeley, CA, USA
| | - John M Bruning
- Department of Biochemical and Cellular Pharmacology, Genentech, South San Francisco, CA, USA
| | - Timothy J Wendorff
- Department of Structural Biology, Genentech, South San Francisco, CA, USA
| | - Wilson Phung
- Department of Microchemistry, Proteomics and Lipidomics, Genentech, South San Francisco, CA, USA
| | - Sarah G Hymowitz
- Department of Structural Biology, Genentech, South San Francisco, CA, USA.
- The Column Group, San Francisco, CA, USA.
| | - Jawahar Sudhamsu
- Department of Structural Biology, Genentech, South San Francisco, CA, USA.
- Department of Discovery Oncology, Genentech, South San Francisco, CA, USA.
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38
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Hauseman ZJ, Fodor M, Dhembi A, Viscomi J, Egli D, Bleu M, Katz S, Park E, Jang DM, Porter KA, Meili F, Guo H, Kerr G, Mollé S, Velez-Vega C, Beyer KS, Galli GG, Maira SM, Stams T, Clark K, Eck MJ, Tordella L, Thoma CR, King DA. Structure of the MRAS-SHOC2-PP1C phosphatase complex. Nature 2022; 609:416-423. [PMID: 35830882 PMCID: PMC9452295 DOI: 10.1038/s41586-022-05086-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 07/07/2022] [Indexed: 11/09/2022]
Abstract
RAS-MAPK signalling is fundamental for cell proliferation and is altered in most human cancers1-3. However, our mechanistic understanding of how RAS signals through RAF is still incomplete. Although studies revealed snapshots for autoinhibited and active RAF-MEK1-14-3-3 complexes4, the intermediate steps that lead to RAF activation remain unclear. The MRAS-SHOC2-PP1C holophosphatase dephosphorylates RAF at serine 259, resulting in the partial displacement of 14-3-3 and RAF-RAS association3,5,6. MRAS, SHOC2 and PP1C are mutated in rasopathies-developmental syndromes caused by aberrant MAPK pathway activation6-14-and SHOC2 itself has emerged as potential target in receptor tyrosine kinase (RTK)-RAS-driven tumours15-18. Despite its importance, structural understanding of the SHOC2 holophosphatase is lacking. Here we determine, using X-ray crystallography, the structure of the MRAS-SHOC2-PP1C complex. SHOC2 bridges PP1C and MRAS through its concave surface and enables reciprocal interactions between all three subunits. Biophysical characterization indicates a cooperative assembly driven by the MRAS GTP-bound active state, an observation that is extendible to other RAS isoforms. Our findings support the concept of a RAS-driven and multi-molecular model for RAF activation in which individual RAS-GTP molecules recruit RAF-14-3-3 and SHOC2-PP1C to produce downstream pathway activation. Importantly, we find that rasopathy and cancer mutations reside at protein-protein interfaces within the holophosphatase, resulting in enhanced affinities and function. Collectively, our findings shed light on a fundamental mechanism of RAS biology and on mechanisms of clinically observed enhanced RAS-MAPK signalling, therefore providing the structural basis for therapeutic interventions.
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Affiliation(s)
| | - Michelle Fodor
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | - Anxhela Dhembi
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | - Jessica Viscomi
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | - David Egli
- Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Melusine Bleu
- Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Stephanie Katz
- Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Eunyoung Park
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Dong Man Jang
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA
| | | | - Fabian Meili
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | - Hongqiu Guo
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | - Grainne Kerr
- Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Sandra Mollé
- Novartis Institutes for BioMedical Research, Basel, Switzerland
| | | | - Kim S Beyer
- Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Giorgio G Galli
- Novartis Institutes for BioMedical Research, Basel, Switzerland
| | | | - Travis Stams
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | - Kirk Clark
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | - Michael J Eck
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Luca Tordella
- Novartis Institutes for BioMedical Research, Basel, Switzerland.
| | - Claudio R Thoma
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA.
| | - Daniel A King
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA.
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Lee E, Liu Z, Nguyen N, Nairn A, Chang AN. Myosin light chain phosphatase catalytic subunit dephosphorylates cardiac myosin via mechanisms dependent and independent of the MYPT regulatory subunits. J Biol Chem 2022; 298:102296. [PMID: 35872014 PMCID: PMC9418503 DOI: 10.1016/j.jbc.2022.102296] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 07/11/2022] [Accepted: 07/12/2022] [Indexed: 11/27/2022] Open
Abstract
Cardiac muscle myosin regulatory light chain (RLC) is constitutively phosphorylated at ∼0.4 mol phosphate/mol RLC in normal hearts, and phosphorylation is maintained by balanced activities of dedicated cardiac muscle–specific myosin light chain kinase and myosin light chain phosphatase (MLCP). Previously, the identity of the cardiac-MLCP was biochemically shown to be similar to the smooth muscle MLCP, which is a well-characterized trimeric protein comprising the regulatory subunit (MYPT1), catalytic subunit PP1cβ, and accessory subunit M20. In smooth muscles in vivo, MYPT1 and PP1cβ co-stabilize each other and are both necessary for normal smooth muscle contractions. In the cardiac muscle, MYPT1 and MYPT2 are both expressed, but contributions to physiological regulation of cardiac myosin dephosphorylation are unclear. We hypothesized that the main catalytic subunit for cardiac-MLCP is PP1cβ, and maintenance of RLC phosphorylation in vivo is dependent on regulation by striated muscle–specific MYPT2. Here, we used PP1cβ conditional knockout mice to biochemically define cardiac-MLCP proteins and developed a cardiac myofibrillar phosphatase assay to measure the direct contribution of MYPT-regulated and MYPT-independent phosphatase activities toward phosphorylated cardiac myosin. We report that (1) PP1cβ is the main isoform expressed in the cardiac myocyte, (2) cardiac muscle pathogenesis in PP1cβ knockout animals involve upregulation of total PP1cα in myocytes and non-muscle cells, (3) the stability of cardiac MYPT1 and MYPT2 proteins in vivo is not dependent on the PP1cβ expression, and (4) phosphorylated myofibrillar cardiac myosin is dephosphorylated by both myosin-targeted and soluble MYPT-independent PP1cβ activities. These results contribute to our understanding of the cardiac-MLCP in vivo.
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Affiliation(s)
- Eunyoung Lee
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas Texas 75390 USA
| | - Zhenan Liu
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas Texas 75390 USA
| | - Nhu Nguyen
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas Texas 75390 USA
| | - Angus Nairn
- Department of Psychiatry, Yale University School of Medicine, New Haven CT 06508 USA
| | - Audrey N Chang
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas Texas 75390 USA; Pak Center for Mineral Metabolism and Clinical Research, UTSW Medical Center, Dallas Texas 75390 USA.
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40
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Abstract
Many kinases use reversible docking interactions to augment the specificity of their catalytic domains. Such docking interactions are often structurally independent of the catalytic domain, which allow for a flexible combination of modules in evolution and in bioengineering. The affinity of docking interactions spans several orders of magnitude. This led us to ask how the affinity of the docking interaction affects enzymatic activity and how to pick the optimal interaction module to complement a given substrate. Here, we develop equations that predict the optimal binding strength of a kinase docking interaction and validate it using numerical simulations and steady-state phosphorylation kinetics for tethered protein kinase A. We show that a kinase-substrate pair has an optimum docking strength that depends on their enzymatic constants, the tether architecture, the substrate concentration, and the kinetics of the docking interactions. We show that a reversible tether enhances phosphorylation rates most when 1) the docking strength is intermediate, 2) the substrate is nonoptimal, 3) the substrate concentration is low, 4) the docking interaction has rapid exchange kinetics, and 5) the tether optimizes the effective concentration of the intramolecular reaction. This work serves as a framework for interpreting mutations in kinase docking interactions and as a design guide for engineering enzyme scaffolds.
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41
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Verdugo-Sivianes EM, Carnero A. SPINOPHILIN: a multiplayer tumor suppressor. Genes Dis 2022; 10:187-198. [PMID: 37013033 PMCID: PMC10066247 DOI: 10.1016/j.gendis.2021.12.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 12/24/2021] [Indexed: 02/07/2023] Open
Abstract
SPINOPHILIN (SPN, PPP1R9B or NEURABIN-2) is a multifunctional protein that regulates protein-protein interactions in different cell signaling pathways. SPN is also one of the regulatory subunits of protein phosphatase 1 (PP1), implicated in the dephosphorylation of retinoblastoma protein (pRB) during cell cycle. The SPN gene has been described as a tumor suppressor in different human tumor contexts, in which low levels of SPN are correlated with a higher grade and worse prognosis. In addition, mutations of the SPN protein have been reported in human tumors. Recently, an oncogenic mutation of SPN, A566V, was described, which affects both the SPN-PP1 interaction and the phosphatase activity of the holoenzyme, and promotes p53-dependent tumorigenesis by increasing the cancer stem cell (CSC) pool in breast tumors. Thus, the loss or mutation of SPN could be late events that promotes tumor progression by increasing the CSC pool and, eventually, the malignant behavior of the tumor.
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Frontotemporal Lobar Dementia Mutant Tau Impairs Axonal Transport through a Protein Phosphatase 1γ-Dependent Mechanism. J Neurosci 2021; 41:9431-9451. [PMID: 34607969 PMCID: PMC8580143 DOI: 10.1523/jneurosci.1914-20.2021] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 08/19/2021] [Accepted: 08/21/2021] [Indexed: 11/21/2022] Open
Abstract
Pathologic tau modifications are characteristic of Alzheimer's disease and related dementias, but mechanisms of tau toxicity continue to be debated. Inherited mutations in tau cause early onset frontotemporal lobar dementias (FTLD-tau) and are commonly used to model mechanisms of tau toxicity in tauopathies. Previous work in the isolated squid axoplasm model demonstrated that several pathogenic forms of tau inhibit axonal transport through a mechanism involving activation of protein phosphatase 1 (PP1). Here, we determined that P301L and R5L FTLD mutant tau proteins elicit a toxic effect on axonal transport as monomeric proteins. We evaluated interactions of wild-type or mutant tau with specific PP1 isoforms (α, β, and γ) to examine how the interaction contributes to this toxic effect using primary rat hippocampal neurons from both sexes. Pull-down and bioluminescence resonance energy transfer experiments revealed selective interactions of wild-type tau with PP1α and PP1γ isoforms, but not PP1β, which were significantly increased by the P301L tau mutation. The results from proximity ligation assays confirmed the interaction in primary hippocampal neurons. Moreover, expression of FTLD-linked mutant tau in these neurons enhanced levels of active PP1, also increasing the pausing frequency of fluorescently labeled vesicles in both anterograde and retrograde directions. Knockdown of PP1γ, but not PP1α, rescued the cargo-pausing effects of P301L and R5L tau, a result replicated by deleting a phosphatase-activating domain in the amino terminus of P301L tau. These findings support a model of tau toxicity involving aberrant activation of a specific PP1γ-dependent pathway that disrupts axonal transport in neurons. SIGNIFICANCE STATEMENT Tau pathology is closely associated with neurodegeneration in Alzheimer's disease and other tauopathies, but the toxic mechanisms remain a debated topic. We previously proposed that pathologic tau forms induce dysfunction and degeneration through aberrant activation of a PP1-dependent pathway that disrupts axonal transport. Here, we show that tau directly interacts with specific PP1 isoforms, increasing levels of active PP1. Pathogenic tau mutations enhance this interaction, further increasing active PP1 levels and impairing axonal transport in isolated squid axoplasm and primary hippocampal neurons. Mutant-tau-mediated impairment of axonal transport was mediated by PP1γ and a phosphatase-activating domain located at the amino terminus of tau. This work has important implications for understanding and potentially mitigating tau-mediated neurotoxicity in tauopathies.
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Mathis CL, Barrios AM. Histidine phosphorylation in metalloprotein binding sites. J Inorg Biochem 2021; 225:111606. [PMID: 34555600 DOI: 10.1016/j.jinorgbio.2021.111606] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 08/30/2021] [Accepted: 09/09/2021] [Indexed: 11/26/2022]
Abstract
Post-translational modifications (PTMs) are invaluable regulatory tools for the control of catalytic functionality, protein-protein interactions, and signaling pathways. Historically, the study of phosphorylation as a PTM has been focused on serine, threonine, and tyrosine residues. In contrast, the significance of mammalian histidine phosphorylation remains largely unexplored. This gap in knowledge regarding the molecular basis for histidine phosphorylation as a regulatory agent exists in part because of the relative instability of phosphorylated histidine as compared with phosphorylated serine, threonine and tyrosine. However, the unique metal binding abilities of histidine make it one of the most common metal coordinating ligands in nature, and it is interesting to consider how phosphorylation would change the metal coordinating ability of histidine, and consequently, the properties of the phosphorylated metalloprotein. In this review, we examine eleven metalloproteins that have been shown to undergo reversible histidine phosphorylation at or near their metal binding sites. These proteins are described with respect to their biological activity and structure, with a particular emphasis on how phosphohistidine may tune the primary coordination sphere and protein conformation. Furthermore, several common methods, challenges, and limitations of studying sensitive, high affinity metalloproteins are discussed.
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Affiliation(s)
- Cheryl L Mathis
- Department of Medicinal Chemistry, College of Pharmacy, University of Utah, Salt Lake City, UT 84112, United States
| | - Amy M Barrios
- Department of Medicinal Chemistry, College of Pharmacy, University of Utah, Salt Lake City, UT 84112, United States.
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Fujimitsu K, Yamano H. Dynamic regulation of mitotic ubiquitin ligase APC/C by coordinated Plx1 kinase and PP2A phosphatase action on a flexible Apc1 loop. EMBO J 2021; 40:e107516. [PMID: 34291488 PMCID: PMC8441438 DOI: 10.15252/embj.2020107516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 07/02/2021] [Accepted: 07/06/2021] [Indexed: 11/29/2022] Open
Abstract
The anaphase-promoting complex/cyclosome (APC/C), a multi-subunit ubiquitin ligase essential for cell cycle control, is regulated by reversible phosphorylation. APC/C phosphorylation by cyclin-dependent kinase 1 (Cdk1) promotes Cdc20 co-activator loading in mitosis to form active APC/C-Cdc20. However, detailed phospho-regulation of APC/C dynamics through other kinases and phosphatases is still poorly understood. Here, we show that an interplay between polo-like kinase (Plx1) and PP2A-B56 phosphatase on a flexible loop domain of the subunit Apc1 (Apc1-loop500 ) controls APC/C activity and mitotic progression. Plx1 directly binds to the Apc1-loop500 in a phosphorylation-dependent manner and promotes the formation of APC/C-Cdc20 via Apc3 phosphorylation. Upon phosphorylation of loop residue T532, PP2A-B56 is recruited to the Apc1-loop500 and differentially promotes dissociation of Plx1 and PP2A-B56 through dephosphorylation of Plx1-binding sites. Stable Plx1 binding, which prevents PP2A-B56 recruitment, prematurely activates the APC/C and delays APC/C dephosphorylation during mitotic exit. Furthermore, the phosphorylation status of the Apc1-loop500 is controlled by distant Apc3-loop phosphorylation. Our study suggests that phosphorylation-dependent feedback regulation through flexible loop domains within a macromolecular complex coordinates the activity and dynamics of the APC/C during the cell cycle.
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Affiliation(s)
- Kazuyuki Fujimitsu
- Cell Cycle Control GroupUCL Cancer InstituteUniversity College LondonLondonUK
| | - Hiroyuki Yamano
- Cell Cycle Control GroupUCL Cancer InstituteUniversity College LondonLondonUK
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Phosphatase and Kinase Substrate Specificity Profiling with Pooled Synthetic Peptides and Mass Spectrometry. Methods Mol Biol 2021. [PMID: 34085215 DOI: 10.1007/978-1-0716-1538-6_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Reversible phosphorylation is a pervasive regulatory event in cellular physiology controlled by reciprocal actions of protein kinases and phosphatases. Determining the inherent substrate specificity of kinases and phosphatases is essential for understanding their cellular roles. Synthetic peptides have long served as substrate proxies for defining intrinsic kinase and phosphatase specificities. Here, we describe a high throughput protocol to simultaneously measure specificity constants (kcat/KM) of many synthetic peptide substrates in a single pool using label-free quantitative mass spectrometry. The generation of specificity constants from a single pooled reaction provides a rigorous and rapid comparison of substrate variants to help define an enzyme's specificity. Equally applicable to kinases and phosphatases, as well as other enzyme classes, the protocol consists of three general steps: (1) reaction of enzyme with pooled peptide substrates, each ideally with a unique mass and at concentrations well below KM, (2) analysis of reaction products using liquid chromatography-coupled mass spectrometry (LC-MS), and (3) automated extraction and integration of elution peaks for each substrate/product pair. We incorporate an ionization correction strategy allowing direct calculation of reaction progress, and subsequently kcat/KM, from substrate and product peak areas in a single sample, obviating the need for stable isotope labeling. Peptide consumption is minimal, and high peptide purity and accurate concentrations are not required. Access to a high-resolution LC-MS system is the only nonstandard equipment need. We present an analysis pipeline consisting entirely of established open-source software tools, and demonstrate proof of principle with the highly selective cell cycle phosphatase Cdc14 from Saccharomyces cerevisiae.
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Benedyk TH, Muenzner J, Connor V, Han Y, Brown K, Wijesinghe KJ, Zhuang Y, Colaco S, Stoll GA, Tutt OS, Svobodova S, Svergun DI, Bryant NA, Deane JE, Firth AE, Jeffries CM, Crump CM, Graham SC. pUL21 is a viral phosphatase adaptor that promotes herpes simplex virus replication and spread. PLoS Pathog 2021; 17:e1009824. [PMID: 34398933 PMCID: PMC8389370 DOI: 10.1371/journal.ppat.1009824] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 08/26/2021] [Accepted: 07/23/2021] [Indexed: 12/27/2022] Open
Abstract
The herpes simplex virus (HSV)-1 protein pUL21 is essential for efficient virus replication and dissemination. While pUL21 has been shown to promote multiple steps of virus assembly and spread, the molecular basis of its function remained unclear. Here we identify that pUL21 is a virus-encoded adaptor of protein phosphatase 1 (PP1). pUL21 directs the dephosphorylation of cellular and virus proteins, including components of the viral nuclear egress complex, and we define a conserved non-canonical linear motif in pUL21 that is essential for PP1 recruitment. In vitro evolution experiments reveal that pUL21 antagonises the activity of the virus-encoded kinase pUS3, with growth and spread of pUL21 PP1-binding mutant viruses being restored in adapted strains where pUS3 activity is disrupted. This study shows that virus-directed phosphatase activity is essential for efficient herpesvirus assembly and spread, highlighting the fine balance between kinase and phosphatase activity required for optimal virus replication. Herpes simplex virus (HSV)-1 is a highly prevalent human virus that causes life-long infections. While the most common symptom of HSV-1 infection is orofacial lesions (‘cold sores’), HSV-1 infection can also cause fatal encephalitis and it is a leading cause of infectious blindness. The HSV-1 genome encodes many proteins that dramatically remodel the environment of infected cells to promote virus replication and spread, including enzymes that add phosphate groups (kinases) to cellular and viral proteins in order to fine-tune their function. Here we identify that pUL21 is an HSV-1 protein that binds directly to protein phosphatase 1 (PP1), a highly abundant cellular enzyme that removes phosphate groups from proteins. We demonstrate that pUL21 stimulates the specific dephosphorylation of both cellular and viral proteins, including a component of the viral nuclear egress complex that is essential for efficient assembly of new HSV-1 particles. Furthermore, our in vitro evolution experiments demonstrate that pUL21 antagonises the activity of the HSV-1 kinase pUS3. Our work highlights the precise control that herpesviruses exert upon the protein environment within infected cells, and specifically the careful balance of kinase and phosphatase activity that HSV-1 requires for optimal replication and spread.
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Affiliation(s)
- Tomasz H. Benedyk
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Julia Muenzner
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Viv Connor
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Yue Han
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Katherine Brown
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | | | - Yunhui Zhuang
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Susanna Colaco
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Guido A. Stoll
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Owen S. Tutt
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | | | - Dmitri I. Svergun
- European Molecular Biology Laboratory (EMBL) Hamburg Site, Hamburg, Germany
| | - Neil A. Bryant
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Janet E. Deane
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - Andrew E. Firth
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Cy M. Jeffries
- European Molecular Biology Laboratory (EMBL) Hamburg Site, Hamburg, Germany
| | - Colin M. Crump
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
- * E-mail: (CMC); (SCG)
| | - Stephen C. Graham
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
- * E-mail: (CMC); (SCG)
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Isobe SY, Hiraga SI, Nagao K, Sasanuma H, Donaldson AD, Obuse C. Protein phosphatase 1 acts as a RIF1 effector to suppress DSB resection prior to Shieldin action. Cell Rep 2021; 36:109383. [PMID: 34260925 PMCID: PMC8293623 DOI: 10.1016/j.celrep.2021.109383] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 04/14/2021] [Accepted: 06/21/2021] [Indexed: 12/29/2022] Open
Abstract
DNA double-strand breaks (DSBs) are repaired mainly by non-homologous end joining (NHEJ) or homologous recombination (HR). RIF1 negatively regulates resection through the effector Shieldin, which associates with a short 3' single-stranded DNA (ssDNA) overhang by the MRN (MRE11-RAD50-NBS1) complex, to prevent further resection and HR repair. In this study, we show that RIF1, but not Shieldin, inhibits the accumulation of CtIP at DSB sites immediately after damage, suggesting that RIF1 has another effector besides Shieldin. We find that protein phosphatase 1 (PP1), a known RIF1 effector in replication, localizes at damage sites dependent on RIF1, where it suppresses downstream CtIP accumulation and limits the resection by the MRN complex. PP1 therefore acts as a RIF1 effector distinct from Shieldin. Furthermore, PP1 deficiency in the context of Shieldin depletion elevates HR immediately after irradiation. We conclude that PP1 inhibits resection before the action of Shieldin to prevent precocious HR in the early phase of the damage response.
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Affiliation(s)
- Shin-Ya Isobe
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-Cho, Toyonaka, Osaka 560-0043, Japan
| | - Shin-Ichiro Hiraga
- Institute of Medical Sciences, School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Aberdeen AB25 2ZD, UK
| | - Koji Nagao
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-Cho, Toyonaka, Osaka 560-0043, Japan
| | - Hiroyuki Sasanuma
- Department of Genome Medicine, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Anne D Donaldson
- Institute of Medical Sciences, School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Aberdeen AB25 2ZD, UK
| | - Chikashi Obuse
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-Cho, Toyonaka, Osaka 560-0043, Japan.
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Sandal P, Jong CJ, Merrill RA, Song J, Strack S. Protein phosphatase 2A - structure, function and role in neurodevelopmental disorders. J Cell Sci 2021; 134:270819. [PMID: 34228795 DOI: 10.1242/jcs.248187] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Neurodevelopmental disorders (NDDs), including intellectual disability (ID), autism and schizophrenia, have high socioeconomic impact, yet poorly understood etiologies. A recent surge of large-scale genome or exome sequencing studies has identified a multitude of mostly de novo mutations in subunits of the protein phosphatase 2A (PP2A) holoenzyme that are strongly associated with NDDs. PP2A is responsible for at least 50% of total Ser/Thr dephosphorylation in most cell types and is predominantly found as trimeric holoenzymes composed of catalytic (C), scaffolding (A) and variable regulatory (B) subunits. PP2A can exist in nearly 100 different subunit combinations in mammalian cells, dictating distinct localizations, substrates and regulatory mechanisms. PP2A is well established as a regulator of cell division, growth, and differentiation, and the roles of PP2A in cancer and various neurodegenerative disorders, such as Alzheimer's disease, have been reviewed in detail. This Review summarizes and discusses recent reports on NDDs associated with mutations of PP2A subunits and PP2A-associated proteins. We also discuss the potential impact of these mutations on the structure and function of the PP2A holoenzymes and the etiology of NDDs.
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Affiliation(s)
- Priyanka Sandal
- Department of Neuroscience and Pharmacology, and Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242, USA
| | - Chian Ju Jong
- Department of Neuroscience and Pharmacology, and Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242, USA
| | - Ronald A Merrill
- Department of Neuroscience and Pharmacology, and Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242, USA
| | - Jianing Song
- Department of Neuroscience and Pharmacology, and Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242, USA
| | - Stefan Strack
- Department of Neuroscience and Pharmacology, and Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242, USA
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Verdugo-Sivianes EM, Carnero A. Role of the Holoenzyme PP1-SPN in the Dephosphorylation of the RB Family of Tumor Suppressors During Cell Cycle. Cancers (Basel) 2021; 13:cancers13092226. [PMID: 34066428 PMCID: PMC8124259 DOI: 10.3390/cancers13092226] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 04/29/2021] [Accepted: 05/03/2021] [Indexed: 11/16/2022] Open
Abstract
Simple Summary Cell cycle progression is highly regulated by modulating the phosphorylation status of retinoblastoma (RB) family proteins. This process is controlled by a balance in the action of kinases, such as the complexes formed by cyclin-dependent kinases (CDKs) and cyclins, and phosphatases, mainly the protein phosphatase 1 (PP1). However, while the phosphorylation of the RB family has been largely studied, its dephosphorylation is less known. Recently, the PP1-Spinophilin (SPN) holoenzyme has been described as the main phosphatase responsible for the dephosphorylation of RB proteins during the G0/G1 transition and at the end of G1. Here, we describe the regulation of the phosphorylation status of RB family proteins, giving importance not only to their inactivation by phosphorylation but also to their dephosphorylation to restore the cell cycle. Abstract Cell cycle progression is highly regulated by modulating the phosphorylation status of the retinoblastoma protein (pRB) and the other two members of the RB family, p107 and p130. This process is controlled by a balance in the action of kinases, such as the complexes formed by cyclin-dependent kinases (CDKs) and cyclins, and phosphatases, mainly the protein phosphatase 1 (PP1). However, while the phosphorylation of the RB family has been largely studied, its dephosphorylation is less known. Phosphatases are holoenzymes formed by a catalytic subunit and a regulatory protein with substrate specificity. Recently, the PP1-Spinophilin (SPN) holoenzyme has been described as the main phosphatase responsible for the dephosphorylation of RB proteins during the G0/G1 transition and at the end of G1. Moreover, SPN has been described as a tumor suppressor dependent on PP1 in lung and breast tumors, where it promotes tumorigenesis by increasing the cancer stem cell pool. Therefore, a connection between the cell cycle and stem cell biology has also been proposed via SPN/PP1/RB proteins.
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Affiliation(s)
- Eva M. Verdugo-Sivianes
- Instituto de Biomedicina de Sevilla, IBIS, Hospital Universitario Virgen del Rocio, Consejo Superior de Investigaciones Científicas, Universidad de Sevilla, Avda. Manuel Siurot s/n, 41013 Seville, Spain;
- CIBERONC, Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Amancio Carnero
- Instituto de Biomedicina de Sevilla, IBIS, Hospital Universitario Virgen del Rocio, Consejo Superior de Investigaciones Científicas, Universidad de Sevilla, Avda. Manuel Siurot s/n, 41013 Seville, Spain;
- CIBERONC, Instituto de Salud Carlos III, 28029 Madrid, Spain
- Correspondence: ; Tel.: +34-955-92-31-11
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50
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Regulation of Cardiac PKA Signaling by cAMP and Oxidants. Antioxidants (Basel) 2021; 10:antiox10050663. [PMID: 33923287 PMCID: PMC8146537 DOI: 10.3390/antiox10050663] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 04/16/2021] [Accepted: 04/20/2021] [Indexed: 12/31/2022] Open
Abstract
Pathologies, such as cancer, inflammatory and cardiac diseases are commonly associated with long-term increased production and release of reactive oxygen species referred to as oxidative stress. Thereby, protein oxidation conveys protein dysfunction and contributes to disease progression. Importantly, trials to scavenge oxidants by systemic antioxidant therapy failed. This observation supports the notion that oxidants are indispensable physiological signaling molecules that induce oxidative post-translational modifications in target proteins. In cardiac myocytes, the main driver of cardiac contractility is the activation of the β-adrenoceptor-signaling cascade leading to increased cellular cAMP production and activation of its main effector, the cAMP-dependent protein kinase (PKA). PKA-mediated phosphorylation of substrate proteins that are involved in excitation-contraction coupling are responsible for the observed positive inotropic and lusitropic effects. PKA-actions are counteracted by cellular protein phosphatases (PP) that dephosphorylate substrate proteins and thus allow the termination of PKA-signaling. Both, kinase and phosphatase are redox-sensitive and susceptible to oxidation on critical cysteine residues. Thereby, oxidation of the regulatory PKA and PP subunits is considered to regulate subcellular kinase and phosphatase localization, while intradisulfide formation of the catalytic subunits negatively impacts on catalytic activity with direct consequences on substrate (de)phosphorylation and cardiac contractile function. This review article attempts to incorporate the current perception of the functionally relevant regulation of cardiac contractility by classical cAMP-dependent signaling with the contribution of oxidant modification.
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