1
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Wu CG, Balakrishnan VK, Merrill RA, Parihar PS, Konovolov K, Chen YC, Xu Z, Wei H, Sundaresan R, Cui Q, Wadzinski BE, Swingle MR, Musiyenko A, Chung WK, Honkanen RE, Suzuki A, Huang X, Strack S, Xing Y. B56δ long-disordered arms form a dynamic PP2A regulation interface coupled with global allostery and Jordan's syndrome mutations. Proc Natl Acad Sci U S A 2024; 121:e2310727120. [PMID: 38150499 PMCID: PMC10769853 DOI: 10.1073/pnas.2310727120] [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: 07/01/2023] [Accepted: 11/27/2023] [Indexed: 12/29/2023] Open
Abstract
Intrinsically disordered regions (IDR) and short linear motifs (SLiMs) play pivotal roles in the intricate signaling networks governed by phosphatases and kinases. B56δ (encoded by PPP2R5D) is a regulatory subunit of protein phosphatase 2A (PP2A) with long IDRs that harbor a substrate-mimicking SLiM and multiple phosphorylation sites. De novo missense mutations in PPP2R5D cause intellectual disabilities (ID), macrocephaly, Parkinsonism, and a broad range of neurological symptoms. Our single-particle cryo-EM structures of the PP2A-B56δ holoenzyme reveal that the long, disordered arms at the B56δ termini fold against each other and the holoenzyme core. This architecture suppresses both the phosphatase active site and the substrate-binding protein groove, thereby stabilizing the enzyme in a closed latent form with dual autoinhibition. The resulting interface spans over 190 Å and harbors unfavorable contacts, activation phosphorylation sites, and nearly all residues with ID-associated mutations. Our studies suggest that this dynamic interface is coupled to an allosteric network responsive to phosphorylation and altered globally by mutations. Furthermore, we found that ID mutations increase the holoenzyme activity and perturb the phosphorylation rates, and the severe variants significantly increase the mitotic duration and error rates compared to the normal variant.
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Affiliation(s)
- Cheng-Guo Wu
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin at Madison, School of Medicine and Public Health, Madison, WI53705
- Biophysics Program, University of Wisconsin at Madison, Madison, WI53706
| | - Vijaya K. Balakrishnan
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin at Madison, School of Medicine and Public Health, Madison, WI53705
| | - Ronald A. Merrill
- Department of Neuroscience and Pharmacology, University of Iowa, Iowa City, IA52242
| | - Pankaj S. Parihar
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin at Madison, School of Medicine and Public Health, Madison, WI53705
| | - Kirill Konovolov
- Chemistry Department, University of Wisconsin at Madison, Madison, WI53706
| | - Yu-Chia Chen
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin at Madison, School of Medicine and Public Health, Madison, WI53705
- Molecular and Cellular Pharmacology Program, University of Wisconsin at Madison, Madison, WI53706
| | - Zhen Xu
- Protein and Crystallography Facility, University of Iowa, Iowa City, IA52242
| | - Hui Wei
- The Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY10027
| | - Ramya Sundaresan
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin at Madison, School of Medicine and Public Health, Madison, WI53705
| | - Qiang Cui
- Department of Chemistry, Boston University, Boston, MA02215
| | | | - Mark R. Swingle
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, AL36688
| | - Alla Musiyenko
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, AL36688
| | - Wendy K. Chung
- Department of Pediatrics, Boston Children’s Hospital, Harvard Medical School, Boston, MA02215
| | - Richard E. Honkanen
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, AL36688
| | - Aussie Suzuki
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin at Madison, School of Medicine and Public Health, Madison, WI53705
- Biophysics Program, University of Wisconsin at Madison, Madison, WI53706
- Molecular and Cellular Pharmacology Program, University of Wisconsin at Madison, Madison, WI53706
| | - Xuhui Huang
- Biophysics Program, University of Wisconsin at Madison, Madison, WI53706
- Chemistry Department, University of Wisconsin at Madison, Madison, WI53706
| | - Stefan Strack
- Department of Neuroscience and Pharmacology, University of Iowa, Iowa City, IA52242
| | - Yongna Xing
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin at Madison, School of Medicine and Public Health, Madison, WI53705
- Biophysics Program, University of Wisconsin at Madison, Madison, WI53706
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Fevga C, Tesson C, Carreras Mascaro A, Courtin T, van Coller R, Sakka S, Ferraro F, Farhat N, Bardien S, Damak M, Carr J, Ferrien M, Boumeester V, Hundscheid J, Grillenzoni N, Kessissoglou IA, Kuipers DJS, Quadri M, Corvol JC, Mhiri C, Hassan BA, Breedveld GJ, Lesage S, Mandemakers W, Brice A, Bonifati V. PTPA variants and impaired PP2A activity in early-onset parkinsonism with intellectual disability. Brain 2023; 146:1496-1510. [PMID: 36073231 PMCID: PMC10115167 DOI: 10.1093/brain/awac326] [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: 03/29/2022] [Revised: 06/24/2022] [Accepted: 08/22/2022] [Indexed: 11/13/2022] Open
Abstract
The protein phosphatase 2A complex (PP2A), the major Ser/Thr phosphatase in the brain, is involved in a number of signalling pathways and functions, including the regulation of crucial proteins for neurodegeneration, such as alpha-synuclein, tau and LRRK2. Here, we report the identification of variants in the PTPA/PPP2R4 gene, encoding a major PP2A activator, in two families with early-onset parkinsonism and intellectual disability. We carried out clinical studies and genetic analyses, including genome-wide linkage analysis, whole-exome sequencing, and Sanger sequencing of candidate variants. We next performed functional studies on the disease-associated variants in cultured cells and knock-down of ptpa in Drosophila melanogaster. We first identified a homozygous PTPA variant, c.893T>G (p.Met298Arg), in patients from a South African family with early-onset parkinsonism and intellectual disability. Screening of a large series of additional families yielded a second homozygous variant, c.512C>A (p.Ala171Asp), in a Libyan family with a similar phenotype. Both variants co-segregate with disease in the respective families. The affected subjects display juvenile-onset parkinsonism and intellectual disability. The motor symptoms were responsive to treatment with levodopa and deep brain stimulation of the subthalamic nucleus. In overexpression studies, both the PTPA p.Ala171Asp and p.Met298Arg variants were associated with decreased PTPA RNA stability and decreased PTPA protein levels; the p.Ala171Asp variant additionally displayed decreased PTPA protein stability. Crucially, expression of both variants was associated with decreased PP2A complex levels and impaired PP2A phosphatase activation. PTPA orthologue knock-down in Drosophila neurons induced a significant impairment of locomotion in the climbing test. This defect was age-dependent and fully reversed by L-DOPA treatment. We conclude that bi-allelic missense PTPA variants associated with impaired activation of the PP2A phosphatase cause autosomal recessive early-onset parkinsonism with intellectual disability. Our findings might also provide new insights for understanding the role of the PP2A complex in the pathogenesis of more common forms of neurodegeneration.
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Affiliation(s)
- Christina Fevga
- Department of Clinical Genetics, Erasmus University Medical Center Rotterdam, Erasmus MC, 3015 GD Rotterdam, The Netherlands
| | - Christelle Tesson
- Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, Sorbonne Université, Paris, France
| | - Ana Carreras Mascaro
- Department of Clinical Genetics, Erasmus University Medical Center Rotterdam, Erasmus MC, 3015 GD Rotterdam, The Netherlands
| | - Thomas Courtin
- Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, Sorbonne Université, Paris, France
- Assistance Publique Hôpitaux de Paris, Hôpital Pitié-Salpêtrière, Département de Génétique, DMU BioGeM, Paris, France
| | - Riaan van Coller
- Department of Neurology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| | - Salma Sakka
- Research Unit in Neurogenetics, Clinical Investigation Center (CIC) at the CHU Habib Bourguiba, Sfax, Tunisia
| | - Federico Ferraro
- Department of Clinical Genetics, Erasmus University Medical Center Rotterdam, Erasmus MC, 3015 GD Rotterdam, The Netherlands
| | - Nouha Farhat
- Research Unit in Neurogenetics, Clinical Investigation Center (CIC) at the CHU Habib Bourguiba, Sfax, Tunisia
| | - Soraya Bardien
- Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
- South African Medical Research Council/Stellenbosch University Genomics of Brain Disorders Research Unit, Stellenbosch University, Cape Town, South Africa
| | - Mariem Damak
- Research Unit in Neurogenetics, Clinical Investigation Center (CIC) at the CHU Habib Bourguiba, Sfax, Tunisia
| | - Jonathan Carr
- Division of Neurology, Department of Medicine, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Mélanie Ferrien
- Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, Sorbonne Université, Paris, France
| | - Valerie Boumeester
- Department of Clinical Genetics, Erasmus University Medical Center Rotterdam, Erasmus MC, 3015 GD Rotterdam, The Netherlands
| | - Jasmijn Hundscheid
- Department of Clinical Genetics, Erasmus University Medical Center Rotterdam, Erasmus MC, 3015 GD Rotterdam, The Netherlands
| | - Nicola Grillenzoni
- Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, Sorbonne Université, Paris, France
| | - Irini A Kessissoglou
- Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, Sorbonne Université, Paris, France
| | - Demy J S Kuipers
- Department of Clinical Genetics, Erasmus University Medical Center Rotterdam, Erasmus MC, 3015 GD Rotterdam, The Netherlands
| | - Marialuisa Quadri
- Department of Clinical Genetics, Erasmus University Medical Center Rotterdam, Erasmus MC, 3015 GD Rotterdam, The Netherlands
| | - Jean-Christophe Corvol
- Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, Sorbonne Université, Paris, France
- Assistance Publique Hôpitaux de Paris, Hôpital Pitié-Salpêtrière, Département de Neurologie, Centre d'Investigation Clinique Neurosciences, DMU Neuroscience, Paris, France
| | - Chokri Mhiri
- Research Unit in Neurogenetics, Clinical Investigation Center (CIC) at the CHU Habib Bourguiba, Sfax, Tunisia
| | - Bassem A Hassan
- Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, Sorbonne Université, Paris, France
| | - Guido J Breedveld
- Department of Clinical Genetics, Erasmus University Medical Center Rotterdam, Erasmus MC, 3015 GD Rotterdam, The Netherlands
| | - Suzanne Lesage
- Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, Sorbonne Université, Paris, France
| | - Wim Mandemakers
- Department of Clinical Genetics, Erasmus University Medical Center Rotterdam, Erasmus MC, 3015 GD Rotterdam, The Netherlands
| | - Alexis Brice
- Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, Sorbonne Université, Paris, France
- Assistance Publique Hôpitaux de Paris, Hôpital Pitié-Salpêtrière, Département de Génétique, DMU BioGeM, Paris, France
| | - Vincenzo Bonifati
- Department of Clinical Genetics, Erasmus University Medical Center Rotterdam, Erasmus MC, 3015 GD Rotterdam, The Netherlands
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Wu CG, Balakrishnan VK, Parihar PS, Konovolov K, Chen YC, Merrill RA, Wei H, Carragher B, Sundaresan R, Cui Q, Wadzinski BE, Swingle MR, Musiyenko A, Honkanen R, Chung WK, Suzuki A, Strack S, Huang X, Xing Y. Extended regulation interface coupled to the allosteric network and disease mutations in the PP2A-B56δ holoenzyme. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.09.530109. [PMID: 37066309 PMCID: PMC10103954 DOI: 10.1101/2023.03.09.530109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
An increasing number of mutations associated with devastating human diseases are diagnosed by whole-genome/exon sequencing. Recurrent de novo missense mutations have been discovered in B56δ (encoded by PPP2R5D), a regulatory subunit of protein phosphatase 2A (PP2A), that cause intellectual disabilities (ID), macrocephaly, Parkinsonism, and a broad range of neurological symptoms. Single-particle cryo-EM structures show that the PP2A-B56δ holoenzyme possesses closed latent and open active forms. In the closed form, the long, disordered arms of B56δ termini fold against each other and the holoenzyme core, establishing dual autoinhibition of the phosphatase active site and the substrate-binding protein groove. The resulting interface spans over 190 Å and harbors unfavorable contacts, activation phosphorylation sites, and nearly all residues with ID-associated mutations. Our studies suggest that this dynamic interface is close to an allosteric network responsive to activation phosphorylation and altered globally by mutations. Furthermore, we found that ID mutations perturb the activation phosphorylation rates, and the severe variants significantly increase the mitotic duration and error rates compared to the wild variant.
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Affiliation(s)
- Cheng-Guo Wu
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin at Madison, School of Medicine and Public Health, Madison, Wisconsin 53705, USA
- Biophysics program, University of Wisconsin at Madison, Wisconsin 53706, USA
| | - Vijaya K. Balakrishnan
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin at Madison, School of Medicine and Public Health, Madison, Wisconsin 53705, USA
| | - Pankaj S. Parihar
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin at Madison, School of Medicine and Public Health, Madison, Wisconsin 53705, USA
| | - Kirill Konovolov
- Chemistry Department, University of Wisconsin at Madison, Wisconsin 53706, USA
| | - Yu-Chia Chen
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin at Madison, School of Medicine and Public Health, Madison, Wisconsin 53705, USA
- Molecular and Cellular Pharmacology program, University of Wisconsin at Madison, Wisconsin 53706, USA
| | - Ronald A Merrill
- Department of Neuroscience and Pharmacology, University of Iowa, Iowa City, IA 52242, USA
| | - Hui Wei
- New York Structural biology Center, New York, NY 10027, USA
| | | | - Ramya Sundaresan
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin at Madison, School of Medicine and Public Health, Madison, Wisconsin 53705, USA
| | - Qiang Cui
- Department of Chemistry, Metcalf Center for Science & Engineering, Boston University, Boston, MA 02215, USA
| | - Brian E. Wadzinski
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
| | - Mark R. Swingle
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, AL 36688, USA
| | - Alla Musiyenko
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, AL 36688, USA
| | - Richard Honkanen
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, AL 36688, USA
| | - Wendy K. Chung
- Departments of Pediatrics and Medicine, Columbia University, New York, NY 10032, USA
| | - Aussie Suzuki
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin at Madison, School of Medicine and Public Health, Madison, Wisconsin 53705, USA
- Biophysics program, University of Wisconsin at Madison, Wisconsin 53706, USA
- Department of Neuroscience and Pharmacology, University of Iowa, Iowa City, IA 52242, USA
| | - Stefan Strack
- Department of Neuroscience and Pharmacology, University of Iowa, Iowa City, IA 52242, USA
| | - Xuhui Huang
- Biophysics program, University of Wisconsin at Madison, Wisconsin 53706, USA
- Chemistry Department, University of Wisconsin at Madison, Wisconsin 53706, USA
| | - Yongna Xing
- McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin at Madison, School of Medicine and Public Health, Madison, Wisconsin 53705, USA
- Biophysics program, University of Wisconsin at Madison, Wisconsin 53706, USA
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4
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Vaneynde P, Verbinnen I, Janssens V. The role of serine/threonine phosphatases in human development: Evidence from congenital disorders. Front Cell Dev Biol 2022; 10:1030119. [PMID: 36313552 PMCID: PMC9608770 DOI: 10.3389/fcell.2022.1030119] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Accepted: 09/27/2022] [Indexed: 11/23/2022] Open
Abstract
Reversible protein phosphorylation is a fundamental regulation mechanism in eukaryotic cell and organismal physiology, and in human health and disease. Until recently, and unlike protein kinases, mutations in serine/threonine protein phosphatases (PSP) had not been commonly associated with disorders of human development. Here, we have summarized the current knowledge on congenital diseases caused by mutations, inherited or de novo, in one of 38 human PSP genes, encoding a monomeric phosphatase or a catalytic subunit of a multimeric phosphatase. In addition, we highlight similar pathogenic mutations in genes encoding a specific regulatory subunit of a multimeric PSP. Overall, we describe 19 affected genes, and find that most pathogenic variants are loss-of-function, with just a few examples of gain-of-function alterations. Moreover, despite their widespread tissue expression, the large majority of congenital PSP disorders are characterised by brain-specific abnormalities, suggesting a generalized, major role for PSPs in brain development and function. However, even if the pathogenic mechanisms are relatively well understood for a small number of PSP disorders, this knowledge is still incomplete for most of them, and the further identification of downstream targets and effectors of the affected PSPs is eagerly awaited through studies in appropriate in vitro and in vivo disease models. Such lacking studies could elucidate the exact mechanisms through which these diseases act, and possibly open up new therapeutic avenues.
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Affiliation(s)
- Pieter Vaneynde
- Laboratory of Protein Phosphorylation and Proteomics, Department of Cellular and Molecular Medicine, University of Leuven (KU Leuven), Leuven, Belgium
- Leuven Brain Institute (LBI), Leuven, Belgium
| | - Iris Verbinnen
- Laboratory of Protein Phosphorylation and Proteomics, Department of Cellular and Molecular Medicine, University of Leuven (KU Leuven), Leuven, Belgium
- Leuven Brain Institute (LBI), Leuven, Belgium
| | - Veerle Janssens
- Laboratory of Protein Phosphorylation and Proteomics, Department of Cellular and Molecular Medicine, University of Leuven (KU Leuven), Leuven, Belgium
- Leuven Brain Institute (LBI), Leuven, Belgium
- *Correspondence: Veerle Janssens,
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5
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Oyama N, Vaneynde P, Reynhout S, Pao EM, Timms A, Fan X, Foss K, Derua R, Janssens V, Chung W, Mirzaa GM. Clinical, neuroimaging and molecular characteristics of PPP2R5D-related neurodevelopmental disorders: an expanded series with functional characterisation and genotype-phenotype analysis. J Med Genet 2022; 60:511-522. [PMID: 36216457 DOI: 10.1136/jmg-2022-108713] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 09/11/2022] [Indexed: 11/03/2022]
Abstract
BACKGROUND Variants in PPP2R5D, affecting the regulatory B56δ subunit of protein phosphatase 2A (PP2A), have been identified in individuals with neurodevelopmental abnormalities. However, the molecular and clinical spectra remain incompletely understood. METHODS Individuals with PPP2R5D variants were enrolled through Simons Variation in Individuals Project/Simons Searchlight. Data were collected from medical history interviews, medical record review, online validated instruments and neuroimaging review. Genetic variants were biochemically characterised. RESULTS We studied 76 individuals with PPP2R5D variants, including 68 with pathogenic de novo variants, four with a variant of uncertain significance (VUS) and four siblings with a novel dominantly inherited pathogenic variant. Among 13 pathogenic variants, eight were novel and two (p.Glu198Lys and p.Glu200Lys) were highly recurrent. Functional analysis revealed impaired PP2A A/C-subunit binding, decreased short linear interaction motif-dependent substrate binding or both-with the most severe phenotypes associated with variants that completely retained one of these binding characteristics and lost the other-further supporting a dominant-negative disease mechanism. p.Glu198Lys showed the highest C-binding defect and a more severe clinical phenotype. The inherited p.Glu197Gly variant had a mild substrate binding defect, and three of four VUS had no biochemical impact. Common clinical phenotypes were language, intellectual or learning disabilities (80.6%), hypotonia (75.0%), macrocephaly (66.7%), seizures (45.8%) and autism spectrum disorder (26.4%). The mean composite Vineland score was 59.8, and most participants were in the 'moderate to low' and 'low' adaptive levels in all domains. CONCLUSION Our study delineates the most common features of PPP2R5D-related neurodevelopmental disorders, expands the clinical and molecular spectrum and identifies genotype-phenotype correlations.
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Affiliation(s)
- Nora Oyama
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Pieter Vaneynde
- Laboratory of Protein Phosphorylation and Proteomics, Department of Cellular and Molecular Medicine, University of Leuven (KU Leuven), Leuven, Belgium.,KU Leuven Brain Institute (LBI), Leuven, Belgium
| | - Sara Reynhout
- Laboratory of Protein Phosphorylation and Proteomics, Department of Cellular and Molecular Medicine, University of Leuven (KU Leuven), Leuven, Belgium.,KU Leuven Brain Institute (LBI), Leuven, Belgium
| | - Emily M Pao
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Andrew Timms
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Xiao Fan
- Department of Pediatrics, Columbia University, New York City, New York, USA
| | - Kimberly Foss
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Rita Derua
- Laboratory of Protein Phosphorylation and Proteomics, Department of Cellular and Molecular Medicine, University of Leuven (KU Leuven), Leuven, Belgium.,SyBioMa, University of Leuven (KU Leuven), Leuven, Belgium
| | - Veerle Janssens
- Laboratory of Protein Phosphorylation and Proteomics, Department of Cellular and Molecular Medicine, University of Leuven (KU Leuven), Leuven, Belgium.,KU Leuven Brain Institute (LBI), Leuven, Belgium
| | - Wendy Chung
- Department of Pediatrics, Columbia University, New York City, New York, USA.,Department of Medicine, Columbia University, New York City, New York, USA
| | - Ghayda M Mirzaa
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA .,Department of Pediatrics, University of Washington, Seattle, Washington, USA
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Dessauges C, Mikelson J, Dobrzyński M, Jacques MA, Frismantiene A, Gagliardi PA, Khammash M, Pertz O. Optogenetic actuator - ERK biosensor circuits identify MAPK network nodes that shape ERK dynamics. Mol Syst Biol 2022; 18:e10670. [PMID: 35694820 PMCID: PMC9189677 DOI: 10.15252/msb.202110670] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 05/16/2022] [Accepted: 05/17/2022] [Indexed: 12/12/2022] Open
Abstract
Combining single-cell measurements of ERK activity dynamics with perturbations provides insights into the MAPK network topology. We built circuits consisting of an optogenetic actuator to activate MAPK signaling and an ERK biosensor to measure single-cell ERK dynamics. This allowed us to conduct RNAi screens to investigate the role of 50 MAPK proteins in ERK dynamics. We found that the MAPK network is robust against most node perturbations. We observed that the ERK-RAF and the ERK-RSK2-SOS negative feedback operate simultaneously to regulate ERK dynamics. Bypassing the RSK2-mediated feedback, either by direct optogenetic activation of RAS, or by RSK2 perturbation, sensitized ERK dynamics to further perturbations. Similarly, targeting this feedback in a human ErbB2-dependent oncogenic signaling model increased the efficiency of a MEK inhibitor. The RSK2-mediated feedback is thus important for the ability of the MAPK network to produce consistent ERK outputs, and its perturbation can enhance the efficiency of MAPK inhibitors.
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Affiliation(s)
| | - Jan Mikelson
- Department of Biosystems Science and Engineering, ETH Zurich, Basel, Switzerland
| | | | | | | | | | - Mustafa Khammash
- Department of Biosystems Science and Engineering, ETH Zurich, Basel, Switzerland
| | - Olivier Pertz
- Institute of Cell Biology, University of Bern, Bern, Switzerland
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7
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Zuo Q, Liao L, Yao ZT, Liu YP, Wang DK, Li SJ, Yin XF, He QY, Xu WW. Targeting PP2A with lomitapide suppresses colorectal tumorigenesis through the activation of AMPK/Beclin1-mediated autophagy. Cancer Lett 2021; 521:281-293. [PMID: 34509534 DOI: 10.1016/j.canlet.2021.09.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 08/08/2021] [Accepted: 09/07/2021] [Indexed: 12/12/2022]
Abstract
Colorectal cancer (CRC) is one of the most common malignancies worldwide, and effective therapy remains a challenge. In this study, we take advantage of a drug repurposing strategy to screen small molecules with novel anticancer activities in a small-molecule library consisting of 1056 FDA-approved drugs. We show, for the first time, that lomitapide, a lipid-lowering agent, exhibits antitumor properties in vitro and in vivo. Activated autophagy is characterized as a key biological process in lomitapide-induced CRC repression. Mechanistically, lomitapide stimulated mitochondrial dysfunction-mediated AMPK activation, resulting in increased AMPK phosphorylation and enhanced Beclin1/Atg14/Vps34 interactions, provoking autophagy induction. Autophagy inhibition or AMPK silencing significantly abrogated lomitapide-induced cell death, indicating the significance of AMPK-regulated autophagy in the antitumor activities of lomitapide. More importantly, PP2A was identified as a direct target of lomitapide by limited proteolysis-mass spectrometry (LiP-SMap), and the bioactivity of lomitapide was attenuated in PP2A-deficient cells, suggesting that the anticancer effect of lomitapide occurs in a PP2A-dependent manner. Taken together, the results of the study reveal that lomitapide can be repositioned as a potential therapeutic drug for CRC treatment.
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Affiliation(s)
- Qian Zuo
- MOE Key Laboratory of Tumor Molecular Biology and Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou, 510632, China
| | - Long Liao
- MOE Key Laboratory of Tumor Molecular Biology and Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou, 510632, China
| | - Zi-Ting Yao
- MOE Key Laboratory of Tumor Molecular Biology and Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou, 510632, China
| | - Ya-Ping Liu
- MOE Key Laboratory of Tumor Molecular Biology and Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou, 510632, China
| | - Ding-Kang Wang
- MOE Key Laboratory of Tumor Molecular Biology and Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou, 510632, China
| | - Shu-Jun Li
- MOE Key Laboratory of Tumor Molecular Biology and Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou, 510632, China
| | - Xing-Feng Yin
- MOE Key Laboratory of Tumor Molecular Biology and Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou, 510632, China
| | - Qing-Yu He
- MOE Key Laboratory of Tumor Molecular Biology and Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou, 510632, China
| | - Wen-Wen Xu
- MOE Key Laboratory of Tumor Molecular Biology and Guangdong Provincial Key Laboratory of Bioengineering Medicine, National Engineering Research Center of Genetic Medicine, Institute of Biomedicine, College of Life Science and Technology, Jinan University, Guangzhou, 510632, China.
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8
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Protein Phosphatase 2A (PP2A) mutations in brain function, development, and neurologic disease. Biochem Soc Trans 2021; 49:1567-1588. [PMID: 34241636 DOI: 10.1042/bst20201313] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 06/09/2021] [Accepted: 06/11/2021] [Indexed: 12/15/2022]
Abstract
By removing Ser/Thr-specific phosphorylations in a multitude of protein substrates in diverse tissues, Protein Phosphatase type 2A (PP2A) enzymes play essential regulatory roles in cellular signalling and physiology, including in brain function and development. Here, we review current knowledge on PP2A gene mutations causally involved in neurodevelopmental disorders and intellectual disability, focusing on PPP2CA, PPP2R1A and PPP2R5D. We provide insights into the impact of these mutations on PP2A structure, substrate specificity and potential function in neurobiology and brain development.
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9
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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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10
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Suzuki A, Sugiyama G, Ohyama Y, Kumamaru W, Yamada T, Mori Y. Regulation of NF-kB Signalling Through the PR55β-RelA Interaction in Osteoblasts. In Vivo 2020; 34:601-608. [PMID: 32111759 DOI: 10.21873/invivo.11813] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Revised: 11/14/2019] [Accepted: 11/15/2019] [Indexed: 02/04/2023]
Abstract
BACKGROUND/AIM Nuclear factor kappa B (NF-kB) signalling including the RelA subunit is activated upon fibroblast growth factor (FGF) stimulation. A clear understanding of the mechanisms underlying this action will provide insights into molecular targeting therapy. Furthermore, protein phosphatase 2A (PP2A) is involved in RelA dephosphorylation, but little is known about the underlying mechanism. MATERIALS AND METHODS Because the regulatory subunits of PP2A drive NF-kB signalling via RelA, we used qRT-PCR and immunoblot analysis to investigate the expression of these subunits in MC3T3-E1 cells. We examined weather FGF2 interacts with NF-kB using immunocytochemistry (IC), immunoprecipitation (IP), and pull-down assay (PD) using recombinant proteins. RESULTS PR55β expression was increased, whereas activated RelA was dephosphorylated upon FGF2 stimulation. Further, the interaction of PR55β with RelA was confirmed by IC, IP, and PD. CONCLUSION FGF2-induced PR55β directly interacts with RelA and regulates NF-kB signalling.
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Affiliation(s)
- Azusa Suzuki
- Section of Oral and Maxillofacial Surgery, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Goro Sugiyama
- Section of Oral and Maxillofacial Surgery, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Yukiko Ohyama
- Section of Oral and Maxillofacial Surgery, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Wataru Kumamaru
- Section of Oral and Maxillofacial Surgery, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Tomohiro Yamada
- Section of Oral and Maxillofacial Surgery, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Yoshihide Mori
- Section of Oral and Maxillofacial Surgery, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
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11
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Lenaerts L, Reynhout S, Verbinnen I, Laumonnier F, Toutain A, Bonnet-Brilhault F, Hoorne Y, Joss S, Chassevent AK, Smith-Hicks C, Loeys B, Joset P, Steindl K, Rauch A, Mehta SG, Chung WK, Devriendt K, Holder SE, Jewett T, Baldwin LM, Wilson WG, Towner S, Srivastava S, Johnson HF, Daumer-Haas C, Baethmann M, Ruiz A, Gabau E, Jain V, Varghese V, Al-Beshri A, Fulton S, Wechsberg O, Orenstein N, Prescott K, Childs AM, Faivre L, Moutton S, Sullivan JA, Shashi V, Koudijs SM, Heijligers M, Kivuva E, McTague A, Male A, van Ierland Y, Plecko B, Maystadt I, Hamid R, Hannig VL, Houge G, Janssens V. The broad phenotypic spectrum of PPP2R1A-related neurodevelopmental disorders correlates with the degree of biochemical dysfunction. Genet Med 2020; 23:352-362. [PMID: 33106617 PMCID: PMC7862067 DOI: 10.1038/s41436-020-00981-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 09/15/2020] [Accepted: 09/17/2020] [Indexed: 12/31/2022] Open
Abstract
Purpose Neurodevelopmental disorders (NDD) caused by protein phosphatase 2A (PP2A) dysfunction have mainly been associated with de novo variants in PPP2R5D and PPP2CA, and more rarely in PPP2R1A. Here, we aimed to better understand the latter by characterizing 30 individuals with de novo and often recurrent variants in this PP2A scaffolding Aα subunit. Methods Most cases were identified through routine clinical diagnostics. Variants were biochemically characterized for phosphatase activity and interaction with other PP2A subunits. Results We describe 30 individuals with 16 different variants in PPP2R1A, 21 of whom had variants not previously reported. The severity of developmental delay ranged from mild learning problems to severe intellectual disability (ID) with or without epilepsy. Common features were language delay, hypotonia, and hypermobile joints. Macrocephaly was only seen in individuals without B55α subunit-binding deficit, and these patients had less severe ID and no seizures. Biochemically more disruptive variants with impaired B55α but increased striatin binding were associated with profound ID, epilepsy, corpus callosum hypoplasia, and sometimes microcephaly. Conclusion We significantly expand the phenotypic spectrum of PPP2R1A-related NDD, revealing a broader clinical presentation of the patients and that the functional consequences of the variants are more diverse than previously reported.
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Affiliation(s)
- Lisa Lenaerts
- Laboratory of Protein Phosphorylation & Proteomics, Department of Cellular & Molecular Medicine, University of Leuven (KU Leuven), Leuven, Belgium
| | - Sara Reynhout
- Laboratory of Protein Phosphorylation & Proteomics, Department of Cellular & Molecular Medicine, University of Leuven (KU Leuven), Leuven, Belgium.,KU Leuven Brain Institute (LBI), Leuven, Belgium
| | - Iris Verbinnen
- Laboratory of Protein Phosphorylation & Proteomics, Department of Cellular & Molecular Medicine, University of Leuven (KU Leuven), Leuven, Belgium
| | - Frédéric Laumonnier
- UMR1253, iBrain, University of Tours, INSERM, Tours, France.,Service de Génétique, Centre Hospitalier Régional Universitaire, Tours, France
| | - Annick Toutain
- UMR1253, iBrain, University of Tours, INSERM, Tours, France.,Service de Génétique, Centre Hospitalier Régional Universitaire, Tours, France
| | - Frédérique Bonnet-Brilhault
- UMR1253, iBrain, University of Tours, INSERM, Tours, France.,Excellence Center in Autism and Neurodevelopmental Disorders, Centre Hospitalier Régional Universitaire, Tours, France
| | - Yana Hoorne
- Laboratory of Protein Phosphorylation & Proteomics, Department of Cellular & Molecular Medicine, University of Leuven (KU Leuven), Leuven, Belgium
| | - Shelagh Joss
- West of Scotland Centre for Genomic Medicine, Queen Elizabeth University Hospital, Glasgow, UK
| | | | | | - Bart Loeys
- Center for Medical Genetics, University of Antwerp/Antwerp University Hospital, Antwerp, Belgium
| | - Pascal Joset
- Institute of Medical Genetics, University of Zurich, Schlieren, Zurich, Switzerland
| | - Katharina Steindl
- Institute of Medical Genetics, University of Zurich, Schlieren, Zurich, Switzerland
| | - Anita Rauch
- Institute of Medical Genetics, University of Zurich, Schlieren, Zurich, Switzerland
| | - Sarju G Mehta
- East Anglian Regional Medical Genetics Service, Addenbrookes Hospital, Cambridge, UK
| | - Wendy K Chung
- Columbia University Medical Center, New York, NY, USA
| | - Koenraad Devriendt
- Department of Human Genetics, University of Leuven (KU Leuven), Leuven, Belgium
| | - Susan E Holder
- North West Thames Regional Genetics Service, Harrow, London, UK
| | - Tamison Jewett
- Wake Forest School of Medicine, Wake Forest University, Winston-Salem, NC, USA
| | - Lauren M Baldwin
- Wake Forest School of Medicine, Wake Forest University, Winston-Salem, NC, USA
| | - William G Wilson
- Department of Pediatrics, University of Virginia, Charlottesville, VA, USA
| | - Shelley Towner
- Department of Pediatrics, University of Virginia, Charlottesville, VA, USA
| | | | - Hannah F Johnson
- Department of Neurology, Boston Children's Hospital, Boston, MA, USA
| | | | - Martina Baethmann
- Pediatric Neurology, Sozialpädiatrisches Zentrum, Klinikum Dritter Orden München, Munich, Germany
| | - Anna Ruiz
- Genetics Laboratory, UDIAT-Centre Diagnòstic, Parc Taulí Hospital Universitari, Institut d'Investigació i Innovació Parc Taulí I3PT, Universitat Autònoma de Barcelona, Sabadell, Spain
| | - Elisabeth Gabau
- Paediatric Unit, Parc Taulí Hospital Universitari, Institut d'Investigació i Innovació Parc taulí I3PT, Universitat Autònoma de Barcelona, Sabadell, Spain
| | - Vani Jain
- All Wales Medical Genomics Service, University Hospital of Wales, Cardiff, UK
| | - Vinod Varghese
- All Wales Medical Genomics Service, University Hospital of Wales, Cardiff, UK
| | - Ali Al-Beshri
- Internal Medicine & Medical Genetics, University of Alabama at Birmingham, Birmingham, AL, USA
| | | | - Oded Wechsberg
- Pediatric Genetics Unit, Schneider Children's Medical Center of Israel, Petach Tikva, Israel.,Maccabi Healthcare Services, Tel Aviv, Israel
| | - Naama Orenstein
- Pediatric Genetics Unit, Schneider Children's Medical Center of Israel, Petach Tikva, Israel.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Katrina Prescott
- Yorkshire Regional Genetics Department, Leeds Teaching Hospitals NHS Trust, Leeds, UK
| | - Anne-Marie Childs
- Department of Neurology, Leeds Teaching Hospitals NHS Trust, Leeds, UK
| | - Laurence Faivre
- Centre de référence Anomalies du Développement et Syndromes malformatifs, FHU TRANSLAD, UMR1231 GAD, CHU Dijon et Université de Bourgogne, Dijon, France
| | - Sébastien Moutton
- CPDPN, Pôle mère enfant, Maison de Santé Bordeaux Bagatelle, Talence, France
| | - Jennifer A Sullivan
- Department of Pediatrics, Division of Medical Genetics, Duke University Medical Center, Durham, NC, USA
| | - Vandana Shashi
- Department of Pediatrics, Division of Medical Genetics, Duke University Medical Center, Durham, NC, USA
| | | | - Malou Heijligers
- Department of Clinical Genetics, Maastricht UMC+, Maastricht, The Netherlands
| | - Emma Kivuva
- Royal Devon & Exeter NHS Foundation Trust, Exeter, UK
| | - Amy McTague
- Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London, UK.,Department of Neurology, Great Ormond Street Hospital, London, UK
| | - Alison Male
- Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London, UK.,Department of Neurology, Great Ormond Street Hospital, London, UK
| | | | - Barbara Plecko
- Division of General Pediatrics, Department of Pediatrics and Adolescent Medicine, Medical University of Graz, Graz, Austria
| | - Isabelle Maystadt
- Centre de Génétique Humaine, Institut de Pathologie et de Génétique, Gosselies, Belgium
| | - Rizwan Hamid
- Vanderbilt University Medical Center, Nashville, TN, USA
| | | | - Gunnar Houge
- Department of Medical Genetics, Haukeland University Hospital, Bergen, Norway.
| | - Veerle Janssens
- Laboratory of Protein Phosphorylation & Proteomics, Department of Cellular & Molecular Medicine, University of Leuven (KU Leuven), Leuven, Belgium. .,KU Leuven Brain Institute (LBI), Leuven, Belgium.
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12
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Kruse T, Gnosa SP, Nasa I, Garvanska DH, Hein JB, Nguyen H, Samsøe-Petersen J, Lopez-Mendez B, Hertz EPT, Schwarz J, Pena HS, Nikodemus D, Kveiborg M, Kettenbach AN, Nilsson J. Mechanisms of site-specific dephosphorylation and kinase opposition imposed by PP2A regulatory subunits. EMBO J 2020; 39:e103695. [PMID: 32400009 PMCID: PMC7327492 DOI: 10.15252/embj.2019103695] [Citation(s) in RCA: 66] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 04/03/2020] [Accepted: 04/21/2020] [Indexed: 12/11/2022] Open
Abstract
PP2A is an essential protein phosphatase that regulates most cellular processes through the formation of holoenzymes containing distinct regulatory B‐subunits. Only a limited number of PP2A‐regulated phosphorylation sites are known. This hampers our understanding of the mechanisms of site‐specific dephosphorylation and of its tumor suppressor functions. Here, we develop phosphoproteomic strategies for global substrate identification of PP2A‐B56 and PP2A‐B55 holoenzymes. Strikingly, we find that B‐subunits directly affect the dephosphorylation site preference of the PP2A catalytic subunit, resulting in unique patterns of kinase opposition. For PP2A‐B56, these patterns are further modulated by affinity and position of B56 binding motifs. Our screens identify phosphorylation sites in the cancer target ADAM17 that are regulated through a conserved B56 binding site. Binding of PP2A‐B56 to ADAM17 protease decreases growth factor signaling and tumor development in mice. This work provides a roadmap for the identification of phosphatase substrates and reveals unexpected mechanisms governing PP2A dephosphorylation site specificity and tumor suppressor function.
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Affiliation(s)
- Thomas Kruse
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Sebastian Peter Gnosa
- Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Copenhagen, Denmark
| | - Isha Nasa
- Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth College, Hanover, NH, USA.,Norris Cotton Cancer Center, Lebanon, NH, USA
| | - Dimitriya Hristoforova Garvanska
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jamin B Hein
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Hieu Nguyen
- Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth College, Hanover, NH, USA.,Norris Cotton Cancer Center, Lebanon, NH, USA
| | - Jacob Samsøe-Petersen
- Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Copenhagen, Denmark
| | - Blanca Lopez-Mendez
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Emil Peter Thrane Hertz
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jeanette Schwarz
- Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Copenhagen, Denmark
| | - Hanna Sofia Pena
- Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Copenhagen, Denmark
| | - Denise Nikodemus
- Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Copenhagen, Denmark
| | - Marie Kveiborg
- Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Copenhagen, Denmark
| | - Arminja N Kettenbach
- Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth College, Hanover, NH, USA.,Norris Cotton Cancer Center, Lebanon, NH, USA
| | - Jakob Nilsson
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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13
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Jong CJ, Merrill RA, Wilkerson EM, Herring LE, Graves LM, Strack S. Reduction of protein phosphatase 2A (PP2A) complexity reveals cellular functions and dephosphorylation motifs of the PP2A/B'δ holoenzyme. J Biol Chem 2020; 295:5654-5668. [PMID: 32156701 PMCID: PMC7186168 DOI: 10.1074/jbc.ra119.011270] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 02/21/2020] [Indexed: 12/17/2022] Open
Abstract
Protein phosphatase 2A (PP2A) is a large enzyme family responsible for most cellular Ser/Thr dephosphorylation events. PP2A substrate specificity, localization, and regulation by second messengers rely on more than a dozen regulatory subunits (including B/R2, B'/R5, and B″/R3), which form the PP2A heterotrimeric holoenzyme by associating with a dimer comprising scaffolding (A) and catalytic (C) subunits. Because of partial redundancy and high endogenous expression of PP2A holoenzymes, traditional approaches of overexpressing, knocking down, or knocking out PP2A regulatory subunits have yielded only limited insights into their biological roles and substrates. To this end, here we sought to reduce the complexity of cellular PP2A holoenzymes. We used tetracycline-inducible expression of pairs of scaffolding and regulatory subunits with complementary charge-reversal substitutions in their interaction interfaces. For each of the three regulatory subunit families, we engineered A/B charge-swap variants that could bind to one another, but not to endogenous A and B subunits. Because endogenous Aα was targeted by a co-induced shRNA, endogenous B subunits were rapidly degraded, resulting in expression of predominantly a single PP2A heterotrimer composed of the A/B charge-swap pair and the endogenous catalytic subunit. Using B'δ/PPP2R5D, we show that PP2A complexity reduction, but not PP2A overexpression, reveals a role of this holoenzyme in suppression of extracellular signal-regulated kinase signaling and protein kinase A substrate dephosphorylation. When combined with global phosphoproteomics, the PP2A/B'δ reduction approach identified consensus dephosphorylation motifs in its substrates and suggested that residues surrounding the phosphorylation site play roles in PP2A substrate specificity.
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Affiliation(s)
- Chian Ju Jong
- Department of Neuroscience and Pharmacology and Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242
| | - Ronald A Merrill
- Department of Neuroscience and Pharmacology and Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242
| | - Emily M Wilkerson
- Michael Hooker Proteomics Facility, University of North Carolina, Chapel Hill, North Carolina 27516
| | - Laura E Herring
- Michael Hooker Proteomics Facility, University of North Carolina, Chapel Hill, North Carolina 27516
| | - Lee M Graves
- Michael Hooker Proteomics Facility, University of North Carolina, Chapel Hill, North Carolina 27516
| | - Stefan Strack
- Department of Neuroscience and Pharmacology and Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242.
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14
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Dunkley PR, Dickson PW. Tyrosine hydroxylase phosphorylation
in vivo. J Neurochem 2019; 149:706-728. [DOI: 10.1111/jnc.14675] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 01/23/2019] [Accepted: 01/29/2019] [Indexed: 12/31/2022]
Affiliation(s)
- Peter R. Dunkley
- The School of Biomedical Sciences and Pharmacy and The Hunter Medical Research Institute The University of Newcastle University Drive Callaghan NSW Australia
| | - Phillip W. Dickson
- The School of Biomedical Sciences and Pharmacy and The Hunter Medical Research Institute The University of Newcastle University Drive Callaghan NSW Australia
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15
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Fowle H, Zhao Z, Graña X. PP2A holoenzymes, substrate specificity driving cellular functions and deregulation in cancer. Adv Cancer Res 2019; 144:55-93. [PMID: 31349904 PMCID: PMC9994639 DOI: 10.1016/bs.acr.2019.03.009] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
PP2A is a highly conserved eukaryotic serine/threonine protein phosphatase of the PPP family of phosphatases with fundamental cellular functions. In cells, PP2A targets specific subcellular locations and substrates by forming heterotrimeric holoenzymes, where a core dimer consisting of scaffold (A) and catalytic (C) subunits complexes with one of many B regulatory subunits. PP2A plays a key role in positively and negatively regulating a myriad of cellular processes, as it targets a very sizable fraction of the cellular substrates phosphorylated on Ser/Thr residues. This review focuses on insights made toward the understanding on how the subunit composition and structure of PP2A holoenzymes mediates substrate specificity, the role of substrate modulation in the signaling of cellular division, growth, and differentiation, and its deregulation in cancer.
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Affiliation(s)
- Holly Fowle
- Fels Institute for Cancer Research and Molecular Biology and Temple University Lewis Katz School of Medicine, Philadelphia, PA, United States
| | - Ziran Zhao
- Fels Institute for Cancer Research and Molecular Biology and Temple University Lewis Katz School of Medicine, Philadelphia, PA, United States
| | - Xavier Graña
- Fels Institute for Cancer Research and Molecular Biology and Temple University Lewis Katz School of Medicine, Philadelphia, PA, United States.
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16
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Booker MA, DeLong A. Positive selection analysis highlights key positions in plant PP2A regulatory subunits. PLANT SIGNALING & BEHAVIOR 2017; 12:e1347245. [PMID: 28692336 PMCID: PMC5616155 DOI: 10.1080/15592324.2017.1347245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 06/20/2017] [Accepted: 06/21/2017] [Indexed: 06/07/2023]
Abstract
A versatile hub for cellular control, the eukaryotic protein phosphatase 2A (PP2A) enzyme family is thought to achieve specificity through combinatorial complexity. Phylogenetic analysis has revealed that expansion of PP2A gene families resulted from whole genome duplications followed by non-random gene loss, and selection analysis suggests that retention of B56/PPP2R5 gene family members after genome duplication events was driven by functional diversification. Here we identify the sites at which positive selection is detected in the plant B56 gene family, and discuss the significance of selection at these positions in the context of PP2A holoenzyme structure. The pattern of positive selection observed in the B11 subclade is distinctive, and suggests selective pressure on interactions with substrates and the enzymatic core.
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Affiliation(s)
- Matthew A. Booker
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI, USA
| | - Alison DeLong
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI, USA
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17
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Liu CY, Hsieh FS, Chu PY, Tsai WC, Huang CT, Yu YB, Huang TT, Ko PS, Hung MH, Wang WL, Shiau CW, Chen KF. Carfilzomib induces leukaemia cell apoptosis via inhibiting ELK1/KIAA1524 (Elk-1/CIP2A) and activating PP2A not related to proteasome inhibition. Br J Haematol 2017; 177:726-740. [PMID: 28340282 DOI: 10.1111/bjh.14620] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2016] [Accepted: 12/22/2016] [Indexed: 01/23/2023]
Abstract
Enhancing the tumour suppressive activity of protein phosphatase 2A (PP2A) has been suggested to be an anti-leukaemic strategy. KIAA1524 (also termed CIP2A), an oncoprotein inhibiting PP2A, is associated with disease progression in chronic myeloid leukaemia and may be prognostic in cytogenetically normal acute myeloid leukaemia. Here we demonstrated that the selective proteasome inhibitor, carfilzomib, induced apoptosis in sensitive primary leukaemia cells and in sensitive leukaemia cell lines, associated with KIAA1524 protein downregulation, increased PP2A activity and decreased p-Akt, but not with the proteasome inhibition effect of carfilzomib. Ectopic expression of KIAA1524, or pretreatment with the PP2A inhibitor, okadaic acid, suppressed carfilzomib-induced apoptosis and KIAA1524 downregulation in sensitive cells, whereas co-treatment with the PP2A agonist, forskolin, enhanced carfilzomib-induced apoptosis in resistant cells. Mechanistically, carfilzomib affected KIAA1524 transcription through disturbing ELK1 (Elk-1) binding to the KIAA1524 promoter. Moreover, the drug sensitivity and mechanism of carfilzomib in xenograft mouse models correlated well with the effects of carfilzomib on KIAA1524 and p-Akt expression, as well as PP2A activity. Our data disclosed a novel drug mechanism of carfilzomib in leukaemia cells and suggests the potential therapeutic implication of KIAA1524 in leukaemia treatment.
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Affiliation(s)
- Chun-Yu Liu
- Comprehensive Breast Health Centre, Taipei Veterans General Hospital, Taipei, Taiwan.,Division of Medical Oncology, Department of Oncology, Taipei Veterans General Hospital, Taipei, Taiwan.,School of Medicine, National Yang-Ming University, Taipei, Taiwan.,Division of Haematology and Oncology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Feng-Shu Hsieh
- Department of Medical Research, National Taiwan University Hospital, Taipei, Taiwan
| | - Pei-Yi Chu
- Department of Pathology, Show Chwan Memorial Hospital, Changhua, Taiwan.,School of Medicine, Fu Jen Catholic University, New Taipei City, Taiwan
| | - Wen-Chun Tsai
- Division of Medical Oncology, Department of Oncology, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Chun-Teng Huang
- School of Medicine, National Yang-Ming University, Taipei, Taiwan.,Division of Haematology and Oncology, Department of Medicine, Yang-Ming Branch of Taipei City Hospital, Taipei, Taiwan
| | - Yuan-Bin Yu
- School of Medicine, National Yang-Ming University, Taipei, Taiwan.,Division of Haematology and Oncology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Tzu-Ting Huang
- Comprehensive Breast Health Centre, Taipei Veterans General Hospital, Taipei, Taiwan.,Division of Medical Oncology, Department of Oncology, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Po-Shen Ko
- Division of Medical Oncology, Department of Oncology, Taipei Veterans General Hospital, Taipei, Taiwan.,School of Medicine, National Yang-Ming University, Taipei, Taiwan.,Division of Haematology and Oncology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Man-Hsin Hung
- Division of Medical Oncology, Department of Oncology, Taipei Veterans General Hospital, Taipei, Taiwan.,School of Medicine, National Yang-Ming University, Taipei, Taiwan.,Division of Haematology and Oncology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Wan-Lun Wang
- Division of Medical Oncology, Department of Oncology, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Chung-Wai Shiau
- Institute of Biopharmaceutical Sciences, National Yang-Ming University, Taipei, Taiwan
| | - Kuen-Feng Chen
- Department of Medical Research, National Taiwan University Hospital, Taipei, Taiwan.,National Center of Excellence for Clinical Trial and Research, National Taiwan University Hospital, Taipei, Taiwan
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18
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Wang B, Liu J, Huang P, Xu K, Wang H, Wang X, Guo Z, Xu L. Protein phosphatase 2A inhibition and subsequent cytoskeleton reorganization contributes to cell migration caused by microcystin-LR in human laryngeal epithelial cells (Hep-2). ENVIRONMENTAL TOXICOLOGY 2017; 32:890-903. [PMID: 27393157 DOI: 10.1002/tox.22289] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 05/08/2016] [Accepted: 05/08/2016] [Indexed: 06/06/2023]
Abstract
The major toxic mechanism of Microcystin-LR is inhibition of the activity of protein phosphatase 2A (PP2A), resulting in a series of cytotoxic effects. Our previous studies have demonstrated that microcystin-LR (MCLR) induced very different molecular effects in normal cells and the tumor cell line SMMC7721. To further explore the MCLR toxicity mechanism in tumor cells, human laryngeal epithelial cells (Hep-2) was examined in this study. Western blot, immunofluorescence, immunoprecipitation, and transwell migration assay were used to detect the effects of MCLR on PP2A activity, PP2A substrates, cytoskeleton, and cell migration. The results showed that the protein level of PP2A subunits and the posttranslational modification of the catalytic subunit were altered and that the binding of the AC core enzyme as well as the binding of PP2A/C and α4, was also affected. As PP2A substrates, the phosphorylation of MAPK pathway members, p38, ERK1/2, and the cytoskeleton-associated proteins, Hsp27, VASP, Tau, and Ezrin were increased. Furthermore, MCLR induced reorganization of the cytoskeleton and promoted cell migration. Taken together, direct covalent binding to PP2A/C, alteration of the protein levels and posttranslational modification, as well as the binding of subunits, are the main pattern for the effects of MCLR on PP2A in Hep-2. A dose-dependent change in p-Tau and p-Ezrin due to PP2A inhibition may contribute to the changes in the cytoskeleton and be related to the cell migration in Hep-2. Our data provide a comprehensive exposition of the MCLR mechanism on tumor cells. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 890-903, 2017.
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Affiliation(s)
- Beilei Wang
- Department of Biochemistry, School of Medicine, Zhejiang University, Hangzhou, 310058, China
| | - Jinghui Liu
- Department of Biochemistry, School of Medicine, Zhejiang University, Hangzhou, 310058, China
| | - Pu Huang
- Department of Biochemistry, School of Medicine, Zhejiang University, Hangzhou, 310058, China
| | - Kailun Xu
- Department of Biochemistry, School of Medicine, Zhejiang University, Hangzhou, 310058, China
| | - Hanying Wang
- Department of Biochemistry, School of Medicine, Zhejiang University, Hangzhou, 310058, China
| | - Xiaofeng Wang
- Zhejiang Center for Disease Control and Prevention, Hangzhou, 310051, China
| | - Zonglou Guo
- Department of Biosystem Engineering, College of Biosystem Engineering and Food Science, Zhejiang University, Hangzhou, 310058, China
| | - Lihong Xu
- Department of Biochemistry, School of Medicine, Zhejiang University, Hangzhou, 310058, China
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19
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Kim JL, La Gamma EF, Estabrook T, Kudrick N, Nankova BB. Whole genome expression profiling associates activation of unfolded protein response with impaired production and release of epinephrine after recurrent hypoglycemia. PLoS One 2017; 12:e0172789. [PMID: 28234964 PMCID: PMC5325535 DOI: 10.1371/journal.pone.0172789] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 02/09/2017] [Indexed: 12/25/2022] Open
Abstract
Recurrent hypoglycemia can occur as a major complication of insulin replacement therapy, limiting the long-term health benefits of intense glycemic control in type 1 and advanced type 2 diabetic patients. It impairs the normal counter-regulatory hormonal and behavioral responses to glucose deprivation, a phenomenon known as hypoglycemia associated autonomic failure (HAAF). The molecular mechanisms leading to defective counter-regulation are not completely understood. We hypothesized that both neuronal (excessive cholinergic signaling between the splanchnic nerve fibers and the adrenal medulla) and humoral factors contribute to the impaired epinephrine production and release in HAAF. To gain further insight into the molecular mechanism(s) mediating the blunted epinephrine responses following recurrent hypoglycemia, we utilized a global gene expression profiling approach. We characterized the transcriptomes during recurrent (defective counter-regulation model) and acute hypoglycemia (normal counter-regulation group) in the adrenal medulla of normal Sprague-Dawley rats. Based on comparison analysis of differentially expressed genes, a set of unique genes that are activated only at specific time points after recurrent hypoglycemia were revealed. A complementary bioinformatics analysis of the functional category, pathway, and integrated network indicated activation of the unfolded protein response. Furthermore, at least three additional pathways/interaction networks altered in the adrenal medulla following recurrent hypoglycemia were identified, which may contribute to the impaired epinephrine secretion in HAAF: greatly increased neuropeptide signaling (proenkephalin, neuropeptide Y, galanin); altered ion homeostasis (Na+, K+, Ca2+) and downregulation of genes involved in Ca2+-dependent exocytosis of secretory vesicles. Given the pleiotropic effects of the unfolded protein response in different organs, involved in maintaining glucose homeostasis, these findings uncover broader general mechanisms that arise following recurrent hypoglycemia which may afford clinicians an opportunity to modulate the magnitude of HAAF syndrome.
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Affiliation(s)
- Juhye Lena Kim
- The Regional Neonatal Center, Maria Fareri Children’s Hospital at Westchester Medical Center, Valhalla, New York, United States of America
| | - Edmund F. La Gamma
- The Regional Neonatal Center, Maria Fareri Children’s Hospital at Westchester Medical Center, Valhalla, New York, United States of America
- Departments of Pediatrics, Biochemistry and Molecular Biology, Division of Newborn Medicine, New York Medical College, Valhalla, New York, United States of America
| | - Todd Estabrook
- New York Medical College School of Medicine, Valhalla, New York, United States of America
| | - Necla Kudrick
- The Regional Neonatal Center, Maria Fareri Children’s Hospital at Westchester Medical Center, Valhalla, New York, United States of America
| | - Bistra B. Nankova
- Departments of Pediatrics, Biochemistry and Molecular Biology, Division of Newborn Medicine, New York Medical College, Valhalla, New York, United States of America
- * E-mail:
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20
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Pereira G, Schiebel E. Mitotic exit: Determining the PP2A dephosphorylation program. J Cell Biol 2016; 214:499-501. [PMID: 27551057 PMCID: PMC5004451 DOI: 10.1083/jcb.201608019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 08/04/2016] [Indexed: 11/22/2022] Open
Abstract
In mitotic exit, proteins that were highly phosphorylated are sequentially targeted by the phosphatase PP2A-B55, but what underlies substrate selection is unclear. In this issue, Cundell et al. (2016. J. Cell Biol http://dx.doi.org/10.1083/jcb.201606033) identify the determinants of PP2A-B55's dephosphorylation program, thereby influencing spindle disassembly, nuclear envelope reformation, and cytokinesis.
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Affiliation(s)
- Gislene Pereira
- German Cancer Research Centre, DKFZ-ZMBH Alliance and Centre for Organismal Studies, University of Heidelberg, 69120 Heidelberg, Germany
| | - Elmar Schiebel
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
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21
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Abstract
Protein phosphatase 2A (PP2A) plays a critical multi-faceted role in the regulation of the cell cycle. It is known to dephosphorylate over 300 substrates involved in the cell cycle, regulating almost all major pathways and cell cycle checkpoints. PP2A is involved in such diverse processes by the formation of structurally distinct families of holoenzymes, which are regulated spatially and temporally by specific regulators. Here, we review the involvement of PP2A in the regulation of three cell signaling pathways: wnt, mTOR and MAP kinase, as well as the G1→S transition, DNA synthesis and mitotic initiation. These processes are all crucial for proper cell survival and proliferation and are often deregulated in cancer and other diseases.
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Affiliation(s)
- Nathan Wlodarchak
- a McArdle Laboratory for Cancer Research, University of Wisconsin-Madison , Madison , WI , USA
| | - Yongna Xing
- a McArdle Laboratory for Cancer Research, University of Wisconsin-Madison , Madison , WI , USA
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22
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Sullivan JM, Havrda MC, Kettenbach AN, Paolella BR, Zhang Z, Gerber SA, Israel MA. Phosphorylation Regulates Id2 Degradation and Mediates the Proliferation of Neural Precursor Cells. Stem Cells 2016; 34:1321-31. [PMID: 26756672 DOI: 10.1002/stem.2291] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Revised: 11/23/2015] [Accepted: 12/07/2015] [Indexed: 01/07/2023]
Abstract
Inhibitor of DNA binding proteins (Id1-Id4) function to inhibit differentiation and promote proliferation of many different cell types. Among the Id family members, Id2 has been most extensively studied in the central nervous system (CNS). Id2 contributes to cultured neural precursor cell (NPC) proliferation as well as to the proliferation of CNS tumors such as glioblastoma that are likely to arise from NPC-like cells. We identified three phosphorylation sites near the N-terminus of Id2 in NPCs. To interrogate the importance of Id2 phosphorylation, Id2(-/-) NPCs were modified to express wild type (WT) Id2 or an Id2 mutant protein that could not be phosphorylated at the identified sites. We observed that NPCs expressing this mutant lacking phosphorylation near the N-terminus had higher steady-state levels of Id2 when compared to NPCs expressing WT Id2. This elevated level was the result of a longer half-life and reduced proteasome-mediated degradation. Moreover, NPCs expressing constitutively de-phosphorylated Id2 proliferated more rapidly than NPCs expressing WT Id2, a finding consistent with the well-characterized function of Id2 in driving proliferation. Observing that phosphorylation of Id2 modulates the degradation of this important cell-cycle regulator, we sought to identify a phosphatase that would stabilize Id2 enhancing its activity in NPCs and extended our analysis to include human glioblastoma-derived stem cells (GSCs). We found that expression of the phosphatase PP2A altered Id2 levels. Our findings suggest that inhibition of PP2A may be a novel strategy to regulate the proliferation of normal NPCs and malignant GSCs by decreasing Id2 levels. Stem Cells 2016;34:1321-1331.
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Affiliation(s)
- Jaclyn M Sullivan
- Pharmacology and Toxicology, Norris Cotton Cancer Center, One Medical Center Drive, Lebanon, NH, 03756.,Department of Pharmacology and Toxicology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Matthew C Havrda
- Pharmacology and Toxicology, Norris Cotton Cancer Center, One Medical Center Drive, Lebanon, NH, 03756.,Department of Pediatrics, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Arminja N Kettenbach
- Pharmacology and Toxicology, Norris Cotton Cancer Center, One Medical Center Drive, Lebanon, NH, 03756.,Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Brenton R Paolella
- Pharmacology and Toxicology, Norris Cotton Cancer Center, One Medical Center Drive, Lebanon, NH, 03756.,Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Zhonghua Zhang
- Pharmacology and Toxicology, Norris Cotton Cancer Center, One Medical Center Drive, Lebanon, NH, 03756.,Department of Pediatrics, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Scott A Gerber
- Pharmacology and Toxicology, Norris Cotton Cancer Center, One Medical Center Drive, Lebanon, NH, 03756.,Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA.,Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Mark A Israel
- Pharmacology and Toxicology, Norris Cotton Cancer Center, One Medical Center Drive, Lebanon, NH, 03756.,Department of Pediatrics, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA.,Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
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23
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Kurimchak A, Graña X. PP2A: more than a reset switch to activate pRB proteins during the cell cycle and in response to signaling cues. Cell Cycle 2015; 14:18-30. [PMID: 25483052 PMCID: PMC4612414 DOI: 10.4161/15384101.2014.985069] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
In their active hypophosphorylated state, members of the retinoblastoma family of pocket proteins negatively regulate cell cycle progression at least in part by repressing expression of E2F-dependent genes. Mitogen-dependent activation of G1 and G1/S Cyclin Dependent Kinases (CDKs) results in coordinated hyperphosphorylation and inactivation of these proteins, which no longer bind and repress E2Fs. S and G2/M CDKs maintain pocket protein hyperphosphorylated through the end of mitosis. The inactivating action of inducible CDKs is opposed by the Ser/Thr protein phosphatases PP2A and PP1. Various trimeric PP2A holoenzymes have been implicated in dephosphorylation of pocket proteins in response to specific cellular signals and stresses or as part of an equilibrium with CDKs throughout the cell cycle. PP1 has specifically been implicated in dephosphorylation of pRB in late mitosis and early G1. This review is particularly focused on the emerging role of PP2A as a major hub for integration of growth suppressor signals that require rapid inactivation of pocket proteins. Of note, activation of particular PP2A holoenzymes triggers differential activation of pocket proteins in the presence of active CDKs.
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Affiliation(s)
- Alison Kurimchak
- a Fels Institute for Cancer Research and Molecular Biology and Department of Biochemistry; Temple University School of Medicine ; Philadelphia , PA USA
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24
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McCloy RA, Parker BL, Rogers S, Chaudhuri R, Gayevskiy V, Hoffman NJ, Ali N, Watkins DN, Daly RJ, James DE, Lorca T, Castro A, Burgess A. Global Phosphoproteomic Mapping of Early Mitotic Exit in Human Cells Identifies Novel Substrate Dephosphorylation Motifs. Mol Cell Proteomics 2015; 14:2194-212. [PMID: 26055452 DOI: 10.1074/mcp.m114.046938] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Indexed: 12/27/2022] Open
Abstract
Entry into mitosis is driven by the coordinated phosphorylation of thousands of proteins. For the cell to complete mitosis and divide into two identical daughter cells it must regulate dephosphorylation of these proteins in a highly ordered, temporal manner. There is currently a lack of a complete understanding of the phosphorylation changes that occur during the initial stages of mitotic exit in human cells. Therefore, we performed a large unbiased, global analysis to map the very first dephosphorylation events that occur as cells exit mitosis. We identified and quantified the modification of >16,000 phosphosites on >3300 unique proteins during early mitotic exit, providing up to eightfold greater resolution than previous studies. The data have been deposited to the ProteomeXchange with identifier PXD001559. Only a small fraction (∼ 10%) of phosphorylation sites were dephosphorylated during early mitotic exit and these occurred on proteins involved in critical early exit events, including organization of the mitotic spindle, the spindle assembly checkpoint, and reformation of the nuclear envelope. Surprisingly this enrichment was observed across all kinase consensus motifs, indicating that it is independent of the upstream phosphorylating kinase. Therefore, dephosphorylation of these sites is likely determined by the specificity of phosphatase/s rather than the activity of kinase/s. Dephosphorylation was significantly affected by the amino acids at and surrounding the phosphorylation site, with several unique evolutionarily conserved amino acids correlating strongly with phosphorylation status. These data provide a potential mechanism for the specificity of phosphatases, and how they co-ordinate the ordered events of mitotic exit. In summary, our results provide a global overview of the phosphorylation changes that occur during the very first stages of mitotic exit, providing novel mechanistic insight into how phosphatase/s specifically regulate this critical transition.
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Affiliation(s)
- Rachael A McCloy
- From the ‡The Kinghorn Cancer Center, Garvan Institute of Medical Research, Darlinghurst, NSW, 2010, Australia
| | - Benjamin L Parker
- §The Charles Perkins Center, School of Molecular Bioscience and Sydney Medical School, The University of Sydney, NSW 2006, Australia
| | - Samuel Rogers
- From the ‡The Kinghorn Cancer Center, Garvan Institute of Medical Research, Darlinghurst, NSW, 2010, Australia
| | - Rima Chaudhuri
- §The Charles Perkins Center, School of Molecular Bioscience and Sydney Medical School, The University of Sydney, NSW 2006, Australia
| | - Velimir Gayevskiy
- From the ‡The Kinghorn Cancer Center, Garvan Institute of Medical Research, Darlinghurst, NSW, 2010, Australia
| | - Nolan J Hoffman
- §The Charles Perkins Center, School of Molecular Bioscience and Sydney Medical School, The University of Sydney, NSW 2006, Australia
| | - Naveid Ali
- From the ‡The Kinghorn Cancer Center, Garvan Institute of Medical Research, Darlinghurst, NSW, 2010, Australia
| | - D Neil Watkins
- From the ‡The Kinghorn Cancer Center, Garvan Institute of Medical Research, Darlinghurst, NSW, 2010, Australia; ¶St. Vincent's Clinical School, Faculty of Medicine, UNSW, Darlinghurst, NSW, Australia; ‖Department of Thoracic Medicine, St Vincent's Hospital, Darlinghurst, NSW, 2010, Australia
| | - Roger J Daly
- **Department of Biochemistry and Molecular Biology, School of Biomedical Sciences Monash University, Clatyon, VIC, 3800, Australia
| | - David E James
- §The Charles Perkins Center, School of Molecular Bioscience and Sydney Medical School, The University of Sydney, NSW 2006, Australia
| | - Thierry Lorca
- ‡‡Equipe Labellisée Ligue Nationale Contre le Cancer, Universités Montpellier 2 et 1, Centre de Recherche de Biochimie Macromoléculaire, CNRS UMR 5237, 1919 Route de Mende, 34293 Montpellier cedex 5, France
| | - Anna Castro
- ‡‡Equipe Labellisée Ligue Nationale Contre le Cancer, Universités Montpellier 2 et 1, Centre de Recherche de Biochimie Macromoléculaire, CNRS UMR 5237, 1919 Route de Mende, 34293 Montpellier cedex 5, France
| | - Andrew Burgess
- ¶St. Vincent's Clinical School, Faculty of Medicine, UNSW, Darlinghurst, NSW, Australia; From the ‡The Kinghorn Cancer Center, Garvan Institute of Medical Research, Darlinghurst, NSW, 2010, Australia;
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25
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Loveday C, Tatton-Brown K, Clarke M, Westwood I, Renwick A, Ramsay E, Nemeth A, Campbell J, Joss S, Gardner M, Zachariou A, Elliott A, Ruark E, van Montfort R, Rahman N. Mutations in the PP2A regulatory subunit B family genes PPP2R5B, PPP2R5C and PPP2R5D cause human overgrowth. Hum Mol Genet 2015; 24:4775-9. [PMID: 25972378 PMCID: PMC4527483 DOI: 10.1093/hmg/ddv182] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 05/11/2015] [Indexed: 11/25/2022] Open
Abstract
Overgrowth syndromes comprise a group of heterogeneous disorders characterised by excessive growth parameters, often in association with intellectual disability. To identify new causes of human overgrowth, we have been undertaking trio-based exome sequencing studies in overgrowth patients and their unaffected parents. Prioritisation of functionally relevant genes with multiple unique de novo mutations revealed four mutations in protein phosphatase 2A (PP2A) regulatory subunit B family genes protein phosphatase 2, regulatory Subunit B’, beta (PPP2R5B); protein phosphatase 2, regulatory Subunit B’, gamma (PPP2R5C); and protein phosphatase 2, regulatory Subunit B’, delta (PPP2R5D). This observation in 3 related genes in 111 individuals with a similar phenotype is greatly in excess of the expected number, as determined from gene-specific de novo mutation rates (P = 1.43 × 10−10). Analysis of exome-sequencing data from a follow-up series of overgrowth probands identified a further pathogenic mutation, bringing the total number of affected individuals to 5. Heterozygotes shared similar phenotypic features including increased height, increased head circumference and intellectual disability. The mutations clustered within a region of nine amino acid residues in the aligned protein sequences (P = 1.6 × 10−5). We mapped the mutations onto the crystal structure of the PP2A holoenzyme complex to predict their molecular and functional consequences. These studies suggest that the mutations may affect substrate binding, thus perturbing the ability of PP2A to dephosphorylate particular protein substrates. PP2A is a major negative regulator of v-akt murine thymoma viral oncogene homolog 1 (AKT). Thus, our data further expand the list of genes encoding components of the phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K)/AKT signalling cascade that are disrupted in human overgrowth conditions.
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Affiliation(s)
| | - Katrina Tatton-Brown
- Division of Genetics and Epidemiology, Medical Genetics Unit, St George's University of London, London, UK, Cancer Genetics Unit, Royal Marsden Hospital, London, UK
| | | | - Isaac Westwood
- Cancer Research UK Cancer Therapeutics Unit and Division of Structural Biology, Institute of Cancer Research, London, UK
| | | | | | - Andrea Nemeth
- Department of Clinical Genetics, Churchill Hospital, Oxford, UK
| | - Jennifer Campbell
- Institute of Genetic Medicine, International Centre for Life, Newcastle University, Newcastle upon Tyne, UK
| | - Shelagh Joss
- West of Scotland Genetic Services, Southern General Hospital, Scotland, UK, Yorkshire Regional Clinical Genetics Service, Chapel Allerton Hospital, Leeds, UK and
| | - McKinlay Gardner
- Genetic Health Service New Zealand, Wellington Hospital, Wellington, NZ
| | | | | | | | - Rob van Montfort
- Cancer Research UK Cancer Therapeutics Unit and Division of Structural Biology, Institute of Cancer Research, London, UK
| | | | - Nazneen Rahman
- Division of Genetics and Epidemiology, Cancer Genetics Unit, Royal Marsden Hospital, London, UK,
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26
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Protein phosphatase 2A is involved in the tyrosine hydroxylase phosphorylation regulated by α-synuclein. Neurochem Res 2015; 40:428-37. [PMID: 25567480 DOI: 10.1007/s11064-014-1477-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Revised: 11/03/2014] [Accepted: 11/07/2014] [Indexed: 01/07/2023]
Abstract
α-Synuclein (α-Syn) plays a crucial role in the pathophysiology of Parkinson's disease (PD), the degeneration of dopaminergic neurons. Previous studies have shown that α-Syn regulates dopamine synthesis by binding to and inhibiting tyrosine hydroxylase (TH). In neurons, protein phosphatases (PPs) play a prominent role in directing signaling toward survival or degeneration. This study was to re-evaluate whether α-Syn could regulate the tyrosine hydroxylase phosphorylation by protein phosphatase-2A (PP2A) in dopaminergic MN9D cells and cortex neurons. Our data demonstrated for the first time that α-Syn stimulates PP2A activity and reduces phosphorylation of TH through regulating the methylation of PP2A in dopaminergic MN9D cells and primary cortex neurons. Increased PP2A activity and reduced phosphorylation of PP2A at Y307 (inactive form of PP2A) were observed in α-Syn overexpression dopaminergic cells (Syn) and primary cortex neurons, and the TH phosphorylation relieved by enhancing PP2A methylation in Syn group could be abated by using PP inhibitors, okadaic acid (OKA). OKA could reduce the cell damage and cell apoptosis induced by α-Syn. Thus our findings may provide an insight into the complicated pathogenesis of PD as well as some clues to the development of novel therapeutic strategies targeting at PP2A.
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27
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Dennis MD, Coleman CS, Berg A, Jefferson LS, Kimball SR. REDD1 enhances protein phosphatase 2A-mediated dephosphorylation of Akt to repress mTORC1 signaling. Sci Signal 2014; 7:ra68. [PMID: 25056877 DOI: 10.1126/scisignal.2005103] [Citation(s) in RCA: 102] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The protein kinase mTOR (mechanistic target of rapamycin) in complex 1 (mTORC1) promotes cell growth and proliferation in response to anabolic stimuli, including growth factors and nutrients. Growth factors activate mTORC1 by stimulating the kinase Akt, which phosphorylates and inhibits the tuberous sclerosis complex [TSC; which is composed of TSC1, TSC2, and TBC1D7 (Tre2-Bub2-Cdc16 domain family member 7)], thereby stimulating the mTORC1 activator Rheb (Ras homolog enriched in brain). We identified the mechanism through which REDD1 (regulated in DNA damage and development 1) represses the mTORC1 signaling pathway. We found that REDD1 promoted the protein phosphatase 2A (PP2A)-dependent dephosphorylation of Akt on Thr(308) but not on Ser(473). Consistent with previous studies showing that phosphorylation of Akt on Thr(308), but not on Ser(473), is necessary for phosphorylation of TSC2, we observed a REDD1-dependent reduction in the phosphorylation of TSC2 and subsequently in the activation state of Rheb. REDD1 and PP2A coimmunoprecipitated with Akt from wild-type but not REDD1 knockout mouse embryonic fibroblasts, suggesting that REDD1 may act as a targeting protein for the catalytic subunit of PP2A. Furthermore, binding to both Akt and PP2A was essential for REDD1 to repress signaling to mTORC1. Overall, the results demonstrate that REDD1 acts not only as a repressor of mTORC1 but also as a constant modulator of the phosphorylation of Akt in response to growth factors and nutrients.
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Affiliation(s)
- Michael D Dennis
- Department of Cellular and Molecular Physiology, Penn State University College of Medicine, Hershey, PA 17033, USA
| | - Catherine S Coleman
- Department of Cellular and Molecular Physiology, Penn State University College of Medicine, Hershey, PA 17033, USA
| | - Arthur Berg
- Division of Biostatistics and Bioinformatics, Penn State University College of Medicine, Hershey, PA 17033, USA
| | - Leonard S Jefferson
- Department of Cellular and Molecular Physiology, Penn State University College of Medicine, Hershey, PA 17033, USA
| | - Scot R Kimball
- Department of Cellular and Molecular Physiology, Penn State University College of Medicine, Hershey, PA 17033, USA.
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28
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Complex molecular regulation of tyrosine hydroxylase. J Neural Transm (Vienna) 2014; 121:1451-81. [PMID: 24866693 DOI: 10.1007/s00702-014-1238-7] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Accepted: 05/04/2014] [Indexed: 12/16/2022]
Abstract
Tyrosine hydroxylase, the rate-limiting enzyme in catecholamine biosynthesis, is strictly controlled by several interrelated regulatory mechanisms. Enzyme synthesis is controlled by epigenetic factors, transcription factors, and mRNA levels. Enzyme activity is regulated by end-product feedback inhibition. Phosphorylation of the enzyme is catalyzed by several protein kinases and dephosphorylation is mediated by two protein phosphatases that establish a sensitive process for regulating enzyme activity on a minute-to-minute basis. Interactions between tyrosine hydroxylase and other proteins introduce additional layers to the already tightly controlled production of catecholamines. Tyrosine hydroxylase degradation by the ubiquitin-proteasome coupled pathway represents yet another mechanism of regulation. Here, we revisit the myriad mechanisms that regulate tyrosine hydroxylase expression and activity and highlight their physiological importance in the control of catecholamine biosynthesis.
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29
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Kirchhefer U, Heinick A, König S, Kristensen T, Müller FU, Seidl MD, Boknik P. Protein phosphatase 2A is regulated by protein kinase Cα (PKCα)-dependent phosphorylation of its targeting subunit B56α at Ser41. J Biol Chem 2013; 289:163-76. [PMID: 24225947 DOI: 10.1074/jbc.m113.507996] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Protein phosphatase 2A (PP2A) is a family of multifunctional serine/threonine phosphatases consisting of a catalytic C, a structural A, and a regulatory B subunit. The substrate and therefore the functional specificity of PP2A are determined by the assembly of the enzyme complex with the appropriate regulatory B subunit families, namely B55, B56, PR72, or PR93/PR110. It has been suggested that additional levels of regulating PP2A function may result from the phosphorylation of B56 isoforms. In this study, we identified a novel phosphorylation site at Ser(41) of B56α. This phosphoamino acid residue was efficiently phosphorylated in vitro by PKCα. We detected a 7-fold higher phosphorylation of B56α in failing human hearts compared with nonfailing hearts. Purified PP2A dimeric holoenzyme (subunits C and A) was able to dephosphorylate PKCα-phosphorylated B56α. The potency of B56α for PP2A inhibition was markedly increased by PKCα phosphorylation. PP2A activity was also reduced in HEK293 cells transfected with a B56α mutant, where serine 41 was replaced by aspartic acid, which mimics phosphorylation. More evidence for a functional role of PKCα-dependent phosphorylation of B56α was derived from Fluo-4 fluorescence measurements in phenylephrine-stimulated Flp293 cells. The endoplasmic reticulum Ca(2+) release was increased by 23% by expression of the pseudophosphorylated form compared with wild-type B56α. Taken together, our results suggest that PKCα can modify PP2A activity by phosphorylation of B56α at Ser(41). This interplay between PKCα and PP2A represents a new mechanism to regulate important cellular functions like cellular Ca(2+) homeostasis.
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Affiliation(s)
- Uwe Kirchhefer
- From the Institut für Pharmakologie und Toxikologie, Universitätsklinikum Münster, 48149 Münster, Germany
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Structure of the Ca2+-dependent PP2A heterotrimer and insights into Cdc6 dephosphorylation. Cell Res 2013; 23:931-46. [PMID: 23752926 PMCID: PMC3698643 DOI: 10.1038/cr.2013.77] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2013] [Revised: 04/17/2013] [Accepted: 04/25/2013] [Indexed: 01/07/2023] Open
Abstract
The B″/PR72 family of protein phosphatase 2A (PP2A) is an important PP2A family involved in diverse cellular processes, and uniquely regulated by calcium binding to the regulatory subunit. The PR70 subunit in this family interacts with cell division control 6 (Cdc6), a cell cycle regulator important for control of DNA replication. Here, we report crystal structures of the isolated PR72 and the trimeric PR70 holoenzyme at a resolution of 2.1 and 2.4 Å, respectively, and in vitro characterization of Cdc6 dephosphorylation. The holoenzyme structure reveals that one of the PR70 calcium-binding motifs directly contacts the scaffold subunit, resulting in the most compact scaffold subunit conformation among all PP2A holoenzymes. PR70 also binds distinctively to the catalytic subunit near the active site, which is required for PR70 to enhance phosphatase activity toward Cdc6. Our studies provide a structural basis for unique regulation of B″/PR72 holoenzymes by calcium ions, and suggest the mechanisms for precise control of substrate specificity among PP2A holoenzymes.
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Oberg EA, Nifoussi SK, Gingras AC, Strack S. Selective proteasomal degradation of the B'β subunit of protein phosphatase 2A by the E3 ubiquitin ligase adaptor Kelch-like 15. J Biol Chem 2012; 287:43378-89. [PMID: 23135275 DOI: 10.1074/jbc.m112.420281] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Protein phosphatase 2A (PP2A), a ubiquitous and pleiotropic regulator of intracellular signaling, is composed of a core dimer (AC) bound to a variable (B) regulatory subunit. PP2A is an enzyme family of dozens of heterotrimers with different subcellular locations and cellular substrates dictated by the B subunit. B'β is a brain-specific PP2A regulatory subunit that mediates dephosphorylation of Ca(2+)/calmodulin-dependent protein kinase II and tyrosine hydroxylase. Unbiased proteomic screens for B'β interactors identified Cullin3 (Cul3), a scaffolding component of E3 ubiquitin ligase complexes, and the previously uncharacterized Kelch-like 15 (KLHL15). KLHL15 is one of ∼40 Kelch-like proteins, many of which have been identified as adaptors for the recruitment of substrates to Cul3-based E3 ubiquitin ligases. Here, we report that KLHL15-Cul3 specifically targets B'β to promote turnover of the PP2A subunit by ubiquitylation and proteasomal degradation. Comparison of KLHL15 and B'β tissue expression profiles suggests that the E3 ligase adaptor contributes to selective expression of the PP2A/B'β holoenzyme in the brain. We mapped KLHL15 residues critical for homodimerization as well as interaction with Cul3 and B'β. Explaining PP2A subunit selectivity, the divergent N terminus of B'β was found necessary and sufficient for KLHL15-mediated degradation, with Tyr-52 having an obligatory role. Although KLHL15 can interact with the PP2A/B'β heterotrimer, it only degrades B'β, thus promoting exchange with other regulatory subunits. E3 ligase adaptor-mediated control of PP2A holoenzyme composition thereby adds another layer of regulation to cellular dephosphorylation events.
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Affiliation(s)
- Elizabeth A Oberg
- Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242, USA
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Wu J, Lou H, Alerte TNM, Stachowski EK, Chen J, Singleton AB, Hamilton RL, Perez RG. Lewy-like aggregation of α-synuclein reduces protein phosphatase 2A activity in vitro and in vivo. Neuroscience 2012; 207:288-97. [PMID: 22326202 DOI: 10.1016/j.neuroscience.2012.01.028] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Revised: 12/07/2011] [Accepted: 01/14/2012] [Indexed: 10/14/2022]
Abstract
α-synuclein (α-Syn) is a chaperone-like protein that is highly implicated in Parkinson's disease (PD) as well as in dementia with Lewy bodies (DLB). Rare forms of PD occur in individuals with mutations of α-Syn or triplication of wild type α-Syn, and in both PD and DLB the intraneuronal inclusions known as Lewy bodies contain aggregated α-Syn that is highly phosphorylated on serine 129. In neuronal cells and in the brains of α-Syn overexpressing transgenic mice, soluble α-Syn stimulates the activity of protein phosphatase 2A (PP2A), a major serine/threonine phosphatase. Serine 129 phosphorylation of α-Syn attenuates its stimulatory effects on PP2A and also accelerates α-Syn aggregation; however, it is unknown if aggregation of α-Syn into Lewy bodies impairs PP2A activity. To assess for this, we measured the impact of α-Syn aggregation on PP2A activity in vitro and in vivo. In cell-free assays, aggregated α-Syn had ∼50% less PP2A stimulatory effects than soluble recombinant α-Syn. Similarly in DLB and α-Syn triplication brains, which contain robust α-Syn aggregation with high levels of serine 129 phosphorylation, PP2A activity was also ∼50% attenuated. As α-Syn normally stimulates PP2A activity, our data suggest that overexpression of α-Syn or sequestration of α-Syn into Lewy bodies has the potential to alter the phosphorylation state of key PP2A substrates; raising the possibility that all forms of synucleinopathy will benefit from treatments aimed at optimizing PP2A activity.
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Affiliation(s)
- J Wu
- Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
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Ahn JH, Kim Y, Kim HS, Greengard P, Nairn AC. Protein kinase C-dependent dephosphorylation of tyrosine hydroxylase requires the B56δ heterotrimeric form of protein phosphatase 2A. PLoS One 2011; 6:e26292. [PMID: 22046270 PMCID: PMC3198769 DOI: 10.1371/journal.pone.0026292] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Accepted: 09/24/2011] [Indexed: 11/19/2022] Open
Abstract
Tyrosine hydroxylase, which plays a critical role in regulation of dopamine synthesis, is known to be controlled by phosphorylation at several critical sites. One of these sites, Ser40, is phosphorylated by a number of protein kinases, including protein kinase A. The major protein phosphatase that dephosphorylates Ser40 is protein phosphatase-2A (PP2A). A recent study has also linked protein kinase C to the dephosphorylation of Ser40 [1], but the mechanism is unclear. PP2A isoforms are comprised of catalytic, scaffold, and regulatory subunits, the regulatory B subunits being able to influence cellular localization and substrate selection. In the current study, we find that protein kinase C is able to phosphorylate a key regulatory site in the B56δ subunit leading to activation of PP2A. In turn, activation of the B56δ-containing heterotrimeric form of PP2A is responsible for enhanced dephosphorylation of Ser40 of tyrosine hydroylase in response to stimulation of PKC. In support of this mechanism, down-regulation of B56δ expression in N27 cells using RNAi was found to increase dopamine synthesis. Together these studies reveal molecular details of how protein kinase C is linked to reduced tyrosine hydroxylase activity via control of PP2A, and also add to the complexity of protein kinase/protein phosphatase interactions.
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Affiliation(s)
- Jung-Hyuck Ahn
- Department of Biochemistry, Ewha Womans University School of Medicine, Seoul, Korea
- * E-mail: (JHA); (ACN)
| | - Yong Kim
- Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, New York, United States of America
| | - Hee-Sun Kim
- Department of Molecular Medicine and Tissue Injury Defense Research Center, Ewha Womans University, School of Medicine, Seoul, Korea
| | - Paul Greengard
- Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, New York, United States of America
| | - Angus C. Nairn
- Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, New York, United States of America
- Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut, United States of America
- * E-mail: (JHA); (ACN)
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Slupe AM, Merrill RA, Strack S. Determinants for Substrate Specificity of Protein Phosphatase 2A. Enzyme Res 2011; 2011:398751. [PMID: 21755039 PMCID: PMC3132988 DOI: 10.4061/2011/398751] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Accepted: 04/28/2011] [Indexed: 12/22/2022] Open
Abstract
Protein phosphatase 2A- (PP2A-) catalyzed dephosphorylation of target substrate proteins is widespread and critical for cellular function. PP2A is predominantly found as a heterotrimeric complex of a catalytic subunit (C), a scaffolding subunit (A), and one member of 4 families of regulatory subunits (B). Substrate specificity of the holoenzyme complex is determined by the subcellular locale the complex is confined to, selective incorporation of the B subunit, interactions with endogenous inhibitory proteins, and specific intermolecular interactions between PP2A and target substrates. Here, we discuss recent studies that have advanced our understanding of the molecular determinants for PP2A substrate specificity.
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Affiliation(s)
- Andrew M Slupe
- Department of Pharmacology, University of Iowa, 2-432 BSB, Iowa City, IA 52242, USA
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Rodgers JT, Vogel RO, Puigserver P. Clk2 and B56β mediate insulin-regulated assembly of the PP2A phosphatase holoenzyme complex on Akt. Mol Cell 2011; 41:471-9. [PMID: 21329884 DOI: 10.1016/j.molcel.2011.02.007] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Revised: 11/03/2010] [Accepted: 01/20/2011] [Indexed: 12/20/2022]
Abstract
Akt mediates important cellular decisions involved in growth, survival, and metabolism. The mechanisms by which Akt is phosphorylated and activated in response to growth factors or insulin have been extensively studied, but the molecular regulatory components and dynamics of Akt attenuation are poorly understood. Here we show that a downstream target of insulin-induced Akt activation, Clk2, triggers Akt dephosphorylation through the PP2A phosphatase complex. Clk2 phosphorylates the PP2A regulatory subunit B56β (PPP2R5B, B'β), which is a critical regulatory step in the assembly of the PP2A holoenzyme complex on Akt leading to dephosphorylation of both S473 and T308 Akt sites. Since Akt plays a pivotal role in cellular signaling, these results have important implications for our understanding of Akt regulation in many biological processes.
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Affiliation(s)
- Joseph T Rodgers
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02115, USA
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Daubner SC, Le T, Wang S. Tyrosine hydroxylase and regulation of dopamine synthesis. Arch Biochem Biophys 2010; 508:1-12. [PMID: 21176768 DOI: 10.1016/j.abb.2010.12.017] [Citation(s) in RCA: 623] [Impact Index Per Article: 44.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2010] [Revised: 12/13/2010] [Accepted: 12/15/2010] [Indexed: 01/22/2023]
Abstract
Tyrosine hydroxylase is the rate-limiting enzyme of catecholamine biosynthesis; it uses tetrahydrobiopterin and molecular oxygen to convert tyrosine to DOPA. Its amino terminal 150 amino acids comprise a domain whose structure is involved in regulating the enzyme's activity. Modes of regulation include phosphorylation by multiple kinases at four different serine residues, and dephosphorylation by two phosphatases. The enzyme is inhibited in feedback fashion by the catecholamine neurotransmitters. Dopamine binds to TyrH competitively with tetrahydrobiopterin, and interacts with the R domain. TyrH activity is modulated by protein-protein interactions with enzymes in the same pathway or the tetrahydrobiopterin pathway, structural proteins considered to be chaperones that mediate the neuron's oxidative state, and the protein that transfers dopamine into secretory vesicles. TyrH is modified in the presence of NO, resulting in nitration of tyrosine residues and the glutathionylation of cysteine residues.
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Affiliation(s)
- S Colette Daubner
- Department of Biological Sciences, St. Mary's University, San Antonio, TX 78228, USA.
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Yang J, Phiel C. Functions of B56-containing PP2As in major developmental and cancer signaling pathways. Life Sci 2010; 87:659-66. [PMID: 20934435 DOI: 10.1016/j.lfs.2010.10.003] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Revised: 09/08/2010] [Accepted: 09/23/2010] [Indexed: 12/20/2022]
Abstract
Members of the B'/B56/PR61 family regulatory subunits of PP2A determine the subcellular localization, substrate specificity, and catalytic activity of PP2A in a wide range of biological processes. Here, we summarize the structure and intracellular localization of B56-containing PP2As and review functions of B56-containing PP2As in several major developmental/cancer signaling pathways.
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Affiliation(s)
- Jing Yang
- The Research Institute at Nationwide Children's Hospital, Department of Pediatrics, the Ohio State University, 700 Children's Dr., Columbus, OH, 43205, United States.
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