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Chinthalapudi K, Heissler SM. Structure, regulation, and mechanisms of nonmuscle myosin-2. Cell Mol Life Sci 2024; 81:263. [PMID: 38878079 PMCID: PMC11335295 DOI: 10.1007/s00018-024-05264-6] [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: 03/11/2024] [Revised: 04/24/2024] [Accepted: 04/30/2024] [Indexed: 06/23/2024]
Abstract
Members of the myosin superfamily of molecular motors are large mechanochemical ATPases that are implicated in an ever-expanding array of cellular functions. This review focuses on mammalian nonmuscle myosin-2 (NM2) paralogs, ubiquitous members of the myosin-2 family of filament-forming motors. Through the conversion of chemical energy into mechanical work, NM2 paralogs remodel and shape cells and tissues. This process is tightly controlled in time and space by numerous synergetic regulation mechanisms to meet cellular demands. We review how recent advances in structural biology together with elegant biophysical and cell biological approaches have contributed to our understanding of the shared and unique mechanisms of NM2 paralogs as they relate to their kinetics, regulation, assembly, and cellular function.
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Affiliation(s)
- Krishna Chinthalapudi
- Department of Physiology and Cell Biology, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University College of Medicine, Columbus, OH, 43210, USA
| | - Sarah M Heissler
- Department of Physiology and Cell Biology, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University College of Medicine, Columbus, OH, 43210, USA.
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2
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Hicks D, Giresh K, Wrischnik LA, Weiser DC. The PPP1R15 Family of eIF2-alpha Phosphatase Targeting Subunits (GADD34 and CReP). Int J Mol Sci 2023; 24:17321. [PMID: 38139150 PMCID: PMC10743859 DOI: 10.3390/ijms242417321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2023] [Revised: 12/01/2023] [Accepted: 12/08/2023] [Indexed: 12/24/2023] Open
Abstract
The vertebrate PPP1R15 family consists of the proteins GADD34 (growth arrest and DNA damage-inducible protein 34, the product of the PPP1R15A gene) and CReP (constitutive repressor of eIF2α phosphorylation, the product of the PPP1R15B gene), both of which function as targeting/regulatory subunits for protein phosphatase 1 (PP1) by regulating subcellular localization, modulating substrate specificity and assembling complexes with target proteins. The primary cellular function of these proteins is to facilitate the dephosphorylation of eukaryotic initiation factor 2-alpha (eIF2α) by PP1 during cell stress. In this review, we will provide a comprehensive overview of the cellular function, biochemistry and pharmacology of GADD34 and CReP, starting with a brief introduction of eIF2α phosphorylation via the integrated protein response (ISR). We discuss the roles GADD34 and CReP play as feedback inhibitors of the unfolded protein response (UPR) and highlight the critical function they serve as inhibitors of the PERK-dependent branch, which is particularly important since it can mediate cell survival or cell death, depending on how long the stressful stimuli lasts, and GADD34 and CReP play key roles in fine-tuning this cellular decision. We briefly discuss the roles of GADD34 and CReP homologs in model systems and then focus on what we have learned about their function from knockout mice and human patients, followed by a brief review of several diseases in which GADD34 and CReP have been implicated, including cancer, diabetes and especially neurodegenerative disease. Because of the potential importance of GADD34 and CReP in aspects of human health and disease, we will discuss several pharmacological inhibitors of GADD34 and/or CReP that show promise as treatments and the controversies as to their mechanism of action. This review will finish with a discussion of the biochemical properties of GADD34 and CReP, their regulation and the additional interacting partners that may provide insight into the roles these proteins may play in other cellular pathways. We will conclude with a brief outline of critical areas for future study.
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Affiliation(s)
- Danielle Hicks
- Department of Science, Mathematics and Engineering, Modesto Junior College, Modesto, CA 95350, USA
- Department of Biological Sciences, University of the Pacific, Stockton, CA 95211, USA
| | - Krithika Giresh
- Department of Biological Sciences, University of the Pacific, Stockton, CA 95211, USA
| | - Lisa A. Wrischnik
- Department of Biological Sciences, University of the Pacific, Stockton, CA 95211, USA
| | - Douglas C. Weiser
- Department of Biological Sciences, University of the Pacific, Stockton, CA 95211, USA
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3
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Kirkbride JA, Nilsson GY, Kim JI, Takeya K, Tanaka Y, Tokumitsu H, Suizu F, Eto M. PHI-1, an Endogenous Inhibitor Protein for Protein Phosphatase-1 and a Pan-Cancer Marker, Regulates Raf-1 Proteostasis. Biomolecules 2023; 13:1741. [PMID: 38136612 PMCID: PMC10741526 DOI: 10.3390/biom13121741] [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: 11/14/2023] [Revised: 11/30/2023] [Accepted: 11/30/2023] [Indexed: 12/24/2023] Open
Abstract
Raf-1, a multifunctional kinase, regulates various cellular processes, including cell proliferation, apoptosis, and migration, by phosphorylating MAPK/ERK kinase and interacting with specific kinases. Cellular Raf-1 activity is intricately regulated through pathways involving the binding of regulatory proteins, direct phosphorylation, and the ubiquitin-proteasome axis. In this study, we demonstrate that PHI-1, an endogenous inhibitor of protein phosphatase-1 (PP1), plays a pivotal role in modulating Raf-1 proteostasis within cells. Knocking down endogenous PHI-1 in HEK293 cells using siRNA resulted in increased cell proliferation and reduced apoptosis. This heightened cell proliferation was accompanied by a 15-fold increase in ERK1/2 phosphorylation. Importantly, the observed ERK1/2 hyperphosphorylation was attributable to an upregulation of Raf-1 expression, rather than an increase in Ras levels, Raf-1 Ser338 phosphorylation, or B-Raf levels. The elevated Raf-1 expression, stemming from PHI-1 knockdown, enhanced EGF-induced ERK1/2 phosphorylation through MEK. Moreover, PHI-1 knockdown significantly contributed to Raf-1 protein stability without affecting Raf-1 mRNA levels. Conversely, ectopic PHI-1 expression suppressed Raf-1 protein levels in a manner that correlated with PHI-1's inhibitory potency. Inhibiting PP1 to mimic PHI-1's function using tautomycin led to a reduction in Raf-1 expression. In summary, our findings highlight that the PHI-1-PP1 signaling axis selectively governs Raf-1 proteostasis and cell survival signals.
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Affiliation(s)
- Jason A. Kirkbride
- Department of Molecular Physiology and Biophysics, and Kimmel Cancer Center, Jefferson Medical College, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA 19107, USA
| | - Garbo Young Nilsson
- Department of Molecular Physiology and Biophysics, and Kimmel Cancer Center, Jefferson Medical College, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA 19107, USA
| | - Jee In Kim
- Department of Molecular Physiology and Biophysics, and Kimmel Cancer Center, Jefferson Medical College, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA 19107, USA
- Department of Molecular Medicine, Keimyung University School of Medicine, Daegu 42601, Republic of Korea
| | - Kosuke Takeya
- Department of Veterinary Medicine, Faculty of Veterinary Medicine, Okayama University of Science, Imabari 794-8555, Ehime, Japan (Y.T.)
| | - Yoshinori Tanaka
- Department of Veterinary Medicine, Faculty of Veterinary Medicine, Okayama University of Science, Imabari 794-8555, Ehime, Japan (Y.T.)
| | - Hiroshi Tokumitsu
- Applied Cell Biology, Graduate School of Interdisciplinary Science & Engineering in Health Systems, Okayama University, Okayama 700-8530, Okayama, Japan
| | - Futoshi Suizu
- Oncology Pathology, Department of Pathology and Host-Defense, Faculty of Medicine, Kagawa University, Kita-gun 761-0793, Kagawa, Japan;
| | - Masumi Eto
- Department of Molecular Physiology and Biophysics, and Kimmel Cancer Center, Jefferson Medical College, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA 19107, USA
- Department of Veterinary Medicine, Faculty of Veterinary Medicine, Okayama University of Science, Imabari 794-8555, Ehime, Japan (Y.T.)
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4
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Tsuji-Tamura K, Ogawa M. FOXO1 promotes endothelial cell elongation and angiogenesis by up-regulating the phosphorylation of myosin light chain 2. Angiogenesis 2023; 26:523-545. [PMID: 37488325 DOI: 10.1007/s10456-023-09884-7] [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: 01/06/2023] [Accepted: 07/11/2023] [Indexed: 07/26/2023]
Abstract
The forkhead box O1 (FOXO1) is an important transcription factor related to proliferation, metabolism, and homeostasis, while the major phenotype of FOXO1-null mice is abnormal vascular morphology, such as vessel enlargement and dilation. In in vitro mouse embryonic stem cell (ESC)-differentiation system, Foxo1-/- vascular endothelial cells (ECs) fail to elongate, and mimic the abnormalities of FOXO1-deficiency in vivo. Here, we identified the PPP1R14C gene as the FOXO1 target genes responsible for elongating using transcriptome analyses in ESC-derived ECs (ESC-ECs), and found that the FOXO1-PPP1R14C-myosin light chain 2 (MLC2) axis is required for EC elongation during angiogenesis. MLC2 is phosphorylated by MLC kinase (MLCK) and dephosphorylated by MLC phosphatase (MLCP). PPP1R14C is an inhibitor of PP1, the catalytic subunit of MLCP. The abnormal morphology of Foxo1-/- ESC-ECs was associated with low level of PPP1R14C and loss of MLC2 phosphorylation, which were reversed by PPP1R14C-introduction. Knockdown of either FOXO1 or PPP1R14C suppressed vascular cord formation and reduced MLC2 phosphorylation in human ECs (HUVECs). The mouse and human PPP1R14C locus possesses an enhancer element containing conserved FOXO1-binding motifs. In vivo chemical inhibition of MLC2 phosphorylation caused dilated vascular structures in mouse embryos. Furthermore, foxo1 or ppp1r14c-knockdown zebrafish exhibited vascular malformations, which were also restored by PPP1R14C-introduction. Mechanistically, FOXO1 suppressed MLCP activity by up-regulating PPP1R14C expression, thereby promoting MLC2 phosphorylation and EC elongation, which are necessary for vascular development. Given the importance of MLC2 phosphorylation in cell morphogenesis, this study may provide novel insights into the role of FOXO1 in control of angiogenesis.
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Affiliation(s)
- Kiyomi Tsuji-Tamura
- Oral Biochemistry and Molecular Biology, Department of Oral Health Science, Faculty of Dental Medicine and Graduate School of Dental Medicine, Hokkaido University, Kita 13, Nishi 7, Kita-Ku, Sapporo, 060-8586, Japan.
| | - Minetaro Ogawa
- Department of Cell Differentiation, Institute of Molecular Embryology and Genetics, Kumamoto University, 2-2-1 Honjo, Chuo-Ku, Kumamoto, 860-0811, Japan
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5
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Tängdén T, Gustafsson S, Rao AS, Ingelsson E. A genome-wide association study in a large community-based cohort identifies multiple loci associated with susceptibility to bacterial and viral infections. Sci Rep 2022; 12:2582. [PMID: 35173190 PMCID: PMC8850418 DOI: 10.1038/s41598-022-05838-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 01/14/2022] [Indexed: 12/21/2022] Open
Abstract
There is limited data on host-specific genetic determinants of susceptibility to bacterial and viral infections. Genome-wide association studies using large population cohorts can be a first step towards identifying patients prone to infectious diseases and targets for new therapies. Genetic variants associated with clinically relevant entities of bacterial and viral infections (e.g., abdominal infections, respiratory infections, and sepsis) in 337,484 participants of the UK Biobank cohort were explored by genome-wide association analyses. Cases (n = 81,179) were identified based on ICD-10 diagnosis codes of hospital inpatient and death registries. Functional annotation was performed using gene expression (eQTL) data. Fifty-seven unique genome-wide significant loci were found, many of which are novel in the context of infectious diseases. Some of the detected genetic variants were previously reported associated with infectious, inflammatory, autoimmune, and malignant diseases or key components of the immune system (e.g., white blood cells, cytokines). Fine mapping of the HLA region revealed significant associations with HLA-DQA1, HLA-DRB1, and HLA-DRB4 locus alleles. PPP1R14A showed strong colocalization with abdominal infections and gene expression in sigmoid and transverse colon, suggesting causality. Shared significant loci across infections and non-infectious phenotypes in the UK Biobank cohort were found, suggesting associations for example between SNPs identified for abdominal infections and CRP, rheumatoid arthritis, and diabetes mellitus. We report multiple loci associated with bacterial and viral infections. A better understanding of the genetic determinants of bacterial and viral infections can be useful to identify patients at risk and in the development of new drugs.
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Affiliation(s)
- Thomas Tängdén
- Infection Medicine, Department of Medical Sciences, Uppsala University, Uppsala, Sweden.
| | - Stefan Gustafsson
- Molecular Epidemiology and Science for Life Laboratory, Department of Medical Sciences, Uppsala University, Uppsala, Sweden
| | - Abhiram S Rao
- Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA, 94305, USA
- Stanford Cardiovascular Institute, Stanford University, Stanford, CA, 94305, USA
- Stanford Diabetes Research Center, Stanford University, Stanford, CA, 94305, USA
| | - Erik Ingelsson
- Molecular Epidemiology and Science for Life Laboratory, Department of Medical Sciences, Uppsala University, Uppsala, Sweden
- Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA, 94305, USA
- Stanford Cardiovascular Institute, Stanford University, Stanford, CA, 94305, USA
- Stanford Diabetes Research Center, Stanford University, Stanford, CA, 94305, USA
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6
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Eto M, Katsuki S, Ohashi M, Miyagawa Y, Tanaka Y, Takeya K, Kitazawa T. Possible roles of N- and C-terminal unstructured tails of CPI-17 in regulating Ca<sup>2+</sup> sensitization force of smooth muscle. J Smooth Muscle Res 2022; 58:22-33. [PMID: 35418530 PMCID: PMC9006046 DOI: 10.1540/jsmr.58.22] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
CPI-17 regulates the myosin phosphatase and mediates the agonist-induced contraction of
smooth muscle. PKC and ROCK phosphorylate CPI-17 at Thr38 leading to a conformational
change of the central inhibitory domain (PHIN domain). The N- and C-terminal tails of
CPI-17 are predicted as unstructured loops and their sequences are conserved among
mammals. Here we characterized CPI-17 N- and C-terminal unstructured tails using
recombinant proteins that lack the potions. Recombinant CPI-17 proteins at a physiologic
level (10 µM) were doped into beta-escin-permeabilized smooth muscle strips for
Ca2+ sensitization force measurement. The ectopic full-length CPI-17
augmented the PDBu-induced Ca2+ sensitization force at pCa6.3, indicating
myosin phosphatase inhibition. Deletion of N- and C-terminal tails of CPI-17 attenuated
the extent of PDBu-induced Ca2+-sensitization force. The N-terminal deletion
dampened phosphorylation at Thr38 by protein kinase C (PKC), and the C-terminal truncation
lowered the affinity to the myosin phosphatase. Under the physiologic conditions, PKC and
myosin phosphatase may recognize CPI-17 N-/C-terminal unstructured tails inducing
Ca2+ sensitization force in smooth muscle cells.
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Affiliation(s)
- Masumi Eto
- Biochemistry Unit, Faculty of Veterinary Medicine, Okayama University of Science, 1-3 Ikoino-oka, Imabari, Ehime 794-8555, Japan
| | - Shuichi Katsuki
- Biochemistry Unit, Faculty of Veterinary Medicine, Okayama University of Science, 1-3 Ikoino-oka, Imabari, Ehime 794-8555, Japan
| | - Minami Ohashi
- Biochemistry Unit, Faculty of Veterinary Medicine, Okayama University of Science, 1-3 Ikoino-oka, Imabari, Ehime 794-8555, Japan
| | - Yui Miyagawa
- Biochemistry Unit, Faculty of Veterinary Medicine, Okayama University of Science, 1-3 Ikoino-oka, Imabari, Ehime 794-8555, Japan
| | - Yoshinori Tanaka
- Biochemistry Unit, Faculty of Veterinary Medicine, Okayama University of Science, 1-3 Ikoino-oka, Imabari, Ehime 794-8555, Japan
| | - Kosuke Takeya
- Biochemistry Unit, Faculty of Veterinary Medicine, Okayama University of Science, 1-3 Ikoino-oka, Imabari, Ehime 794-8555, Japan
| | - Toshio Kitazawa
- Department of Mol Physiol & Biophysics, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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7
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Targeting protein phosphatase PP2A for cancer therapy: development of allosteric pharmaceutical agents. Clin Sci (Lond) 2021; 135:1545-1556. [PMID: 34192314 DOI: 10.1042/cs20201367] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 06/15/2021] [Accepted: 07/16/2021] [Indexed: 01/26/2023]
Abstract
Tumor initiation is driven by oncogenes that activate signaling networks for cell proliferation and survival involving protein phosphorylation. Protein kinases in these pathways have proven to be effective targets for pharmaceutical inhibitors that have progressed to the clinic to treat various cancers. Here, we offer a narrative about the development of small molecule modulators of the protein Ser/Thr phosphatase 2A (PP2A) to reduce the activation of cell proliferation and survival pathways. These novel drugs promote the assembly of select heterotrimeric forms of PP2A that act to limit cell proliferation. We discuss the potential for the near-term translation of this approach to the clinic for cancer and other human diseases.
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8
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Mahoney KE, Shabanowitz J, Hunt DF. MHC Phosphopeptides: Promising Targets for Immunotherapy of Cancer and Other Chronic Diseases. Mol Cell Proteomics 2021; 20:100112. [PMID: 34129940 PMCID: PMC8724925 DOI: 10.1016/j.mcpro.2021.100112] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Revised: 05/11/2021] [Accepted: 06/02/2021] [Indexed: 12/27/2022] Open
Abstract
Major histocompatibility complex-associated peptides have been considered as potential immunotherapeutic targets for many years. MHC class I phosphopeptides result from dysregulated cell signaling pathways that are common across cancers and both viral and bacterial infections. These antigens are recognized by central memory T cells from healthy donors, indicating that they are considered antigenic by the immune system and that they are presented across different individuals and diseases. Based on these responses and the similar dysregulation, phosphorylated antigens are promising candidates for prevention or treatment of different cancers as well as a number of other chronic diseases.
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Affiliation(s)
- Keira E Mahoney
- Department of Chemistry, University of Virginia, Charlottesville, Virginia, USA
| | - Jeffrey Shabanowitz
- Department of Chemistry, University of Virginia, Charlottesville, Virginia, USA.
| | - Donald F Hunt
- Department of Chemistry, University of Virginia, Charlottesville, Virginia, USA; Department of Pathology, University of Virginia, Charlottesville, Virginia, USA.
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9
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Chiu AM, Wang J, Fiske MP, Hubalkova P, Barse L, Gray JA, Sanz-Clemente A. NMDAR-Activated PP1 Dephosphorylates GluN2B to Modulate NMDAR Synaptic Content. Cell Rep 2020; 28:332-341.e5. [PMID: 31291571 PMCID: PMC6639021 DOI: 10.1016/j.celrep.2019.06.030] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 04/09/2019] [Accepted: 06/07/2019] [Indexed: 01/07/2023] Open
Abstract
In mature neurons, postsynaptic N-methyl-D-aspartate receptors (NMDARs) are segregated into two populations, synaptic and extrasynaptic, which differ in localization, function, and associated intracellular cascades. These two pools are connected via lateral diffusion, and receptor exchange between them modulates synaptic NMDAR content. Here, we identify the phosphorylation of the PDZ-ligand of the GluN2B subunit of NMDARs (at S1480) as a critical determinant in dynamically controlling NMDAR synaptic content. We find that phosphorylation of GluN2B at S1480 maintains NMDARs at extrasynaptic membranes as part of a protein complex containing protein phosphatase 1 (PP1). Global activation of NMDARs leads to the activation of PP1, which mediates dephosphorylation of GluN2B at S1480 to promote an increase in synaptic NMDAR content. Thus, PP1-mediated dephosphorylation of the GluN2B PDZ-ligand modulates the synaptic expression of NMDARs in mature neurons in an activity-dependent manner, a process with profound consequences for synaptic and structural plasticity, metaplasticity, and synaptic neurotransmission. The dynamic regulation of synaptically expressed NMDA receptors (NMDARs) is essential for synaptic function. Here, Chiu et al. describe a mechanism controlling this process in mature neurons by showing that increases in NMDAR synaptic content are driven by PP1-mediated dephosphorylation of extrasynaptic NMDARs within their GluN2B PDZ-ligands.
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Affiliation(s)
- Andrew M Chiu
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Jiejie Wang
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Department of Neurology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Michael P Fiske
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Pavla Hubalkova
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Department of Cellular Neurophysiology, Institute of Physiology CAS, Prague 142 20, Czech Republic
| | - Levi Barse
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - John A Gray
- Center for Neuroscience, University of California, Davis, Davis, CA 95618, USA
| | - Antonio Sanz-Clemente
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
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10
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Álvarez-Santos MD, Álvarez-González M, Estrada-Soto S, Bazán-Perkins B. Regulation of Myosin Light-Chain Phosphatase Activity to Generate Airway Smooth Muscle Hypercontractility. Front Physiol 2020; 11:701. [PMID: 32676037 PMCID: PMC7333668 DOI: 10.3389/fphys.2020.00701] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 05/28/2020] [Indexed: 12/21/2022] Open
Abstract
Smooth muscle is a central structure involved in the regulation of airway tone. In addition, it plays an important role in the development of some pathologies generated by alterations in contraction, such as hypercontractility and the airway hyperresponsiveness observed in asthma. The molecular processes associated with smooth muscle contraction are centered around myosin light chain (MLC) phosphorylation, which is controlled by a balance in the activity of myosin light-chain kinase (MLCK) and myosin light-chain phosphatase (MLCP). MLCK activation depends on increasing concentrations of intracellular Ca2+, while MLCP activation is independent of Ca2+. MLCP contains a phosphatase subunit (PP1c) that is regulated through myosin phosphatase target subunit 1 (MYPT1) and other subunits, such as glycogen-associated regulatory subunit and myosin-binding subunit 85 kDa. Interestingly, MLCP inhibition may contribute to exacerbation of smooth muscle contraction by increasing MLC phosphorylation to induce hypercontractility. Many pathways inhibiting MLCP activity in airway smooth muscle have been proposed and are focused on inhibition of PP1c, inhibitory phosphorylation of MYPT1 and dissociation of the PP1c-MYPT1 complex.
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Affiliation(s)
- Mayra D Álvarez-Santos
- Biology Area, Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Marisol Álvarez-González
- Laboratorio de Inmunofarmacología, Instituto Nacional de Enfermedades Respiratorias "Ismael Cosío Villegas", Mexico City, Mexico
| | - Samuel Estrada-Soto
- Facultad de Farmacia, Universidad Autónoma del Estado de Morelos, Cuernavaca, Mexico
| | - Blanca Bazán-Perkins
- Laboratorio de Inmunofarmacología, Instituto Nacional de Enfermedades Respiratorias "Ismael Cosío Villegas", Mexico City, Mexico.,Tecnológico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Monterrey, Mexico
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11
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Annunziata MC, Parisi M, Esposito G, Fabbrocini G, Ammendola R, Cattaneo F. Phosphorylation Sites in Protein Kinases and Phosphatases Regulated by Formyl Peptide Receptor 2 Signaling. Int J Mol Sci 2020; 21:ijms21113818. [PMID: 32471307 PMCID: PMC7312799 DOI: 10.3390/ijms21113818] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 05/22/2020] [Accepted: 05/25/2020] [Indexed: 12/19/2022] Open
Abstract
FPR1, FPR2, and FPR3 are members of Formyl Peptides Receptors (FPRs) family belonging to the GPCR superfamily. FPR2 is a low affinity receptor for formyl peptides and it is considered the most promiscuous member of this family. Intracellular signaling cascades triggered by FPRs include the activation of different protein kinases and phosphatase, as well as tyrosine kinase receptors transactivation. Protein kinases and phosphatases act coordinately and any impairment of their activation or regulation represents one of the most common causes of several human diseases. Several phospho-sites has been identified in protein kinases and phosphatases, whose role may be to expand the repertoire of molecular mechanisms of regulation or may be necessary for fine-tuning of switch properties. We previously performed a phospho-proteomic analysis in FPR2-stimulated cells that revealed, among other things, not yet identified phospho-sites on six protein kinases and one protein phosphatase. Herein, we discuss on the selective phosphorylation of Serine/Threonine-protein kinase N2, Serine/Threonine-protein kinase PRP4 homolog, Serine/Threonine-protein kinase MARK2, Serine/Threonine-protein kinase PAK4, Serine/Threonine-protein kinase 10, Dual specificity mitogen-activated protein kinase kinase 2, and Protein phosphatase 1 regulatory subunit 14A, triggered by FPR2 stimulation. We also describe the putative FPR2-dependent signaling cascades upstream to these specific phospho-sites.
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Affiliation(s)
- Maria Carmela Annunziata
- Department of Clinical Medicine and Surgery, School of Medicine, University of Naples Federico II, Via S. Pansini 5, 80131 Naples, Italy; (M.C.A.); (M.P.); (G.F.)
| | - Melania Parisi
- Department of Clinical Medicine and Surgery, School of Medicine, University of Naples Federico II, Via S. Pansini 5, 80131 Naples, Italy; (M.C.A.); (M.P.); (G.F.)
| | - Gabriella Esposito
- Department of Molecular Medicine and Medical Biotechnology, School of Medicine, University of Naples Federico II, Via S. Pansini 5, 80131 Naples, Italy; (G.E.); (R.A.)
| | - Gabriella Fabbrocini
- Department of Clinical Medicine and Surgery, School of Medicine, University of Naples Federico II, Via S. Pansini 5, 80131 Naples, Italy; (M.C.A.); (M.P.); (G.F.)
| | - Rosario Ammendola
- Department of Molecular Medicine and Medical Biotechnology, School of Medicine, University of Naples Federico II, Via S. Pansini 5, 80131 Naples, Italy; (G.E.); (R.A.)
| | - Fabio Cattaneo
- Department of Molecular Medicine and Medical Biotechnology, School of Medicine, University of Naples Federico II, Via S. Pansini 5, 80131 Naples, Italy; (G.E.); (R.A.)
- Correspondence: ; Fax: +39-081-7464-359
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12
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Wang X, Obeidat M, Li L, Pasarj P, Aburahess S, Holmes CFB, Ballermann BJ. TIMAP inhibits endothelial myosin light chain phosphatase by competing with MYPT1 for the catalytic protein phosphatase 1 subunit PP1cβ. J Biol Chem 2019; 294:13280-13291. [PMID: 31315927 PMCID: PMC6737228 DOI: 10.1074/jbc.ra118.006075] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 06/17/2019] [Indexed: 11/06/2022] Open
Abstract
Transforming growth factor-β membrane associated protein (TIMAP) is an endothelial cell (EC)-predominant PP1 regulatory subunit and a member of the myosin phosphatase target (MYPT) protein family. The MYPTs preferentially bind the catalytic protein phosphatase 1 subunit PP1cβ, forming myosin phosphatase holoenzymes. We investigated whether TIMAP/PP1cβ could also function as a myosin phosphatase. Endogenous PP1cβ, myosin light chain 2 (MLC2), and myosin IIA heavy chain coimmunoprecipitated from EC lysates with endogenous TIMAP, and endogenous MLC2 colocalized with TIMAP in EC projections. Purified recombinant GST-TIMAP interacted directly with purified recombinant His-MLC2. However, TIMAP overexpression in EC enhanced MLC2 phosphorylation, an effect not observed with a TIMAP mutant that does not bind PP1cβ. Conversely, MLC2 phosphorylation was reduced in lung lysates from TIMAP-deficient mice and upon silencing of endogenous TIMAP expression in ECs. Ectopically expressed TIMAP slowed the rate of MLC2 dephosphorylation, an effect requiring TIMAP-PP1cβ interaction. The association of MYPT1 with PP1cβ was profoundly reduced in the presence of excess TIMAP, leading to proteasomal MYPT1 degradation. In the absence of TIMAP, MYPT1-associated PP1cβ readily bound immobilized microcystin-LR, an active-site inhibitor of PP1c. By contrast, TIMAP-associated PP1cβ did not interact with microcystin-LR, indicating that the active site of PP1cβ is blocked when it is bound to TIMAP. Thus, TIMAP inhibits myosin phosphatase activity in ECs by competing with MYPT1 for PP1cβ and blocking the PP1cβ active site.
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Affiliation(s)
- Xin Wang
- Department of Medicine, University of Alberta, Edmonton, Alberta T6G 2G3, Canada
| | - Marya Obeidat
- Department of Medicine, University of Alberta, Edmonton, Alberta T6G 2G3, Canada
| | - Laiji Li
- Department of Medicine, University of Alberta, Edmonton, Alberta T6G 2G3, Canada
| | - Phuwadet Pasarj
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2G3, Canada
| | - Salah Aburahess
- Department of Medicine, University of Alberta, Edmonton, Alberta T6G 2G3, Canada
| | - Charles F B Holmes
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2G3, Canada
| | - Barbara J Ballermann
- Department of Medicine, University of Alberta, Edmonton, Alberta T6G 2G3, Canada.
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13
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CPI-17-mediated contraction of vascular smooth muscle is essential for the development of hypertension in obese mice. J Genet Genomics 2019; 46:109-118. [PMID: 30948334 DOI: 10.1016/j.jgg.2019.02.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 01/21/2019] [Accepted: 02/20/2019] [Indexed: 12/14/2022]
Abstract
Several factors have been implicated in obesity-related hypertension, but the genesis of the hypertension is largely unknown. In this study, we found a significantly upregulated expression of CPI-17 (C-kinase-potentiated protein phosphatase 1 inhibitor of 17 kDa) and protein kinase C (PKC) isoforms in the vascular smooth muscles of high-fat diet (HFD)-fed obese mice. The obese wild-type mice showed a significant elevation of blood pressure and enhanced calcium-sensitized contraction of vascular smooth muscles. However, the obese CPI-17-deficient mice showed a normotensive blood pressure, and the calcium-sensitized contraction was consistently reduced. In addition, the mutant muscle displayed an abolished responsive force to a PKC activator and a 30%-50% reduction in both the initial peak force and sustained force in response to various G protein-coupled receptor (GPCR) agonists. Our observations showed that CPI-17-mediated calcium sensitization is mediated through a GPCR/PKC/CPI-17/MLCP/RLC signaling pathway. We therefore propose that the upregulation of CPI-17-mediated calcium-sensitized vasocontraction by obesity contributes to the development of obesity-related hypertension.
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14
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LIMK2-1, a new isoform of human LIMK2, regulates actin cytoskeleton remodeling via a different signaling pathway than that of its two homologs, LIMK2a and LIMK2b. Biochem J 2018; 475:3745-3761. [DOI: 10.1042/bcj20170961] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 10/22/2018] [Accepted: 10/29/2018] [Indexed: 12/29/2022]
Abstract
LIMK1 and LIMK2 (LIMKs, LIM kinases) are kinases that play a crucial role in cytoskeleton dynamics by independently regulating both actin filament and microtubule remodeling. LIMK1 and, more recently, LIMK2 have been shown to be involved in cancer development and metastasis, resistance of cancer cells to microtubule-targeted treatments, neurological diseases, and viral infection. LIMKs have thus recently emerged as new therapeutic targets. Databanks describe three isoforms of human LIMK2: LIMK2a, LIMK2b, and LIMK2-1. Evidence suggests that they may not have completely overlapping functions. We biochemically characterized the three isoforms to better delineate their potential roles, focusing on LIMK2-1, which has only been described at the mRNA level in a single study. LIMK2-1 has a protein phosphatase 1 (PP1) inhibitory domain at its C-terminus which its two counterparts do not. We showed that the LIMK2-1 protein is indeed synthesized. LIMK2-1 does not phosphorylate cofilin, the canonical substrate of LIMKs, although it has kinase activity and promotes actin stress fiber formation. Instead, it interacts with PP1 and partially inhibits its activity towards cofilin. Our data suggest that LIMK2-1 regulates actin cytoskeleton dynamics by preventing PP1-mediated cofilin dephosphorylation, rather than by directly phosphorylating cofilin as its two counterparts, LIMK2a and LIMK2b. This specificity may allow for tight regulation of the phospho-cofilin pool, determining the fate of the cell.
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15
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Successful overexpression of wild-type inhibitor-2 of PP1 in cardiovascular cells. Naunyn Schmiedebergs Arch Pharmacol 2018; 391:859-873. [PMID: 29797049 DOI: 10.1007/s00210-018-1515-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2018] [Accepted: 05/13/2018] [Indexed: 01/16/2023]
Abstract
About half of the cardiac serine/threonine phosphatase activity is due to the activity of protein phosphatase type 1 (PP1). The activity of PP1 can be inhibited by an endogenous protein for which the expression inhibitor-2 (I-2) has been coined. We have previously described a transgenic mouse overexpressing a truncated form of I-2. Here, we have described and initially characterized several founders that overexpress the non-truncated (i.e., full length) I-2 in the mouse heart (TG) and compared them with non-transgenic littermates (WT). The founder with the highest overexpression of I-2 displayed under basal conditions no difference in contractile parameters (heart rate, developed tension, and its first derivate) compared to WT. The relative level of PP1 inhibition was similar in mice overexpressing the non-truncated as well as the truncated form of I-2. For comparison, we overexpressed I-2 by an adenoviral system in several cell lines (myocytes from a tumor-derived cell line (H9C2), neonatal rat cardiomyocytes, smooth muscle cells from rat aorta (A7R5)). We noted gene dosage-dependent staining for I-2 protein in infected cells together with reduced PP1 activity. Finally, I-2 expression in neonatal rat cardiomyocytes led to an increase of Ca2+ transients by about 60%. In summary, we achieved immunologically confirmed overexpression of wild-type I-2 in cardiovascular cells which was biochemically able to inhibit PP1 in the whole heart (using I-2 transgenic mice) as well as in isolated cells including cardiomyocytes (using I-2 coding virus) indirectly underscoring the importance of PP1 for cardiovascular function.
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16
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Yang Q, Fujii W, Kaji N, Kakuta S, Kada K, Kuwahara M, Tsubone H, Ozaki H, Hori M. The essential role of phospho‐T38 CPI‐17 in the maintenance of physiological blood pressure using genetically modified mice. FASEB J 2018; 32:2095-2109. [DOI: 10.1096/fj.201700794r] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
Affiliation(s)
- Qunhui Yang
- Department of Veterinary Pharmacology, Laboratory of Applied Genetics, Department of Biomedical Science, Department of Veterinary Pathophysiology and Animal Health, and Research Center for Food SafetyGraduate School of Agriculture and Life Sciences, The University of TokyoTokyoJapan
| | - Wataru Fujii
- Laboratory of Applied Genetics, Department of Biomedical Science, Department of Veterinary Pathophysiology and Animal Health, and Research Center for Food SafetyGraduate School of Agriculture and Life Sciences, The University of TokyoTokyoJapan
| | - Noriyuki Kaji
- Department of Veterinary Pharmacology, Laboratory of Applied Genetics, Department of Biomedical Science, Department of Veterinary Pathophysiology and Animal Health, and Research Center for Food SafetyGraduate School of Agriculture and Life Sciences, The University of TokyoTokyoJapan
| | - Shigeru Kakuta
- Department of Biomedical Science, Department of Veterinary Pathophysiology and Animal Health, and Research Center for Food SafetyGraduate School of Agriculture and Life Sciences, The University of TokyoTokyoJapan
| | - Kodai Kada
- Department of Veterinary Pharmacology, Laboratory of Applied Genetics, Department of Biomedical Science, Department of Veterinary Pathophysiology and Animal Health, and Research Center for Food SafetyGraduate School of Agriculture and Life Sciences, The University of TokyoTokyoJapan
| | - Masayoshi Kuwahara
- Department of Veterinary Pathophysiology and Animal Health, and Research Center for Food SafetyGraduate School of Agriculture and Life Sciences, The University of TokyoTokyoJapan
| | - Hirokazu Tsubone
- Research Center for Food SafetyGraduate School of Agriculture and Life Sciences, The University of TokyoTokyoJapan
| | - Hiroshi Ozaki
- Department of Veterinary Pharmacology, Laboratory of Applied Genetics, Department of Biomedical Science, Department of Veterinary Pathophysiology and Animal Health, and Research Center for Food SafetyGraduate School of Agriculture and Life Sciences, The University of TokyoTokyoJapan
| | - Masatoshi Hori
- Department of Veterinary Pharmacology, Laboratory of Applied Genetics, Department of Biomedical Science, Department of Veterinary Pathophysiology and Animal Health, and Research Center for Food SafetyGraduate School of Agriculture and Life Sciences, The University of TokyoTokyoJapan
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17
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Wang K, He J, Zhao Y, Wu T, Zhou X, Ding Y, Kong L, Wang X, Wang Y, Li J, Song CP, Wang B, Yang S, Zhu JK, Gong Z. EAR1 Negatively Regulates ABA Signaling by Enhancing 2C Protein Phosphatase Activity. THE PLANT CELL 2018; 30:815-834. [PMID: 29618630 PMCID: PMC5969277 DOI: 10.1105/tpc.17.00875] [Citation(s) in RCA: 90] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 02/08/2018] [Accepted: 04/02/2018] [Indexed: 05/20/2023]
Abstract
The reversible phosphorylation of proteins by kinases and phosphatases is an antagonistic process that modulates many cellular functions. Protein phosphatases are usually negatively regulated by inhibitor proteins. During abscisic acid (ABA) signaling, these inhibitor proteins comprise PYR1/PYL/RCAR ABA receptors, which inhibit the core negative regulators, the clade A type 2C protein phosphatases (PP2Cs). However, it is not known whether these PP2Cs are positively regulated by other proteins. Here, we identified an Arabidopsis thaliana ear1 (enhancer of aba co-receptor1) mutant that exhibits pleiotropic ABA-hypersensitive phenotypes. EAR1 encodes an uncharacterized protein that is conserved in both monocots and dicots. EAR1 interacts with the N-terminal inhibition domains of all six PP2Cs, ABA INSENSITIVE1 (ABI1), ABI2, HYPERSENSITIVE TO ABA1 (HAB1), HAB2, ABA-HYPERSENSITIVE GERMINATION1 (AHG1), and AHG3, during ABA signaling and enhances the activity of PP2Cs both in vitro and in vivo. ABA treatment caused EAR1 to accumulate in the nucleus. These results indicate that EAR1 is a negative regulator of ABA signaling that enhances the activity of PP2Cs by interacting with and releasing the N-terminal autoinhibition of these proteins.
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Affiliation(s)
- Kai Wang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Junna He
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
- College of Horticulture, China Agricultural University, Beijing 100193, China
| | - Yang Zhao
- China Shanghai Center for Plant Stress Biology, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 201602, China
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907
| | - Ting Wu
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Xiaofeng Zhou
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
- College of Horticulture, China Agricultural University, Beijing 100193, China
| | - Yanglin Ding
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Lingyao Kong
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Xiaoji Wang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Yu Wang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Jigang Li
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Chun-Peng Song
- Collaborative Innovation Center of Crop Stress Biology, Henan Province, Institute of Plant Stress Biology, Henan University, Kaifeng 475001, China
| | - Baoshan Wang
- Key Laboratory of Plant Stress Research, College of Life Science, Shandong Normal University, Ji'nan 250014, China
| | - Shuhua Yang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Jian-Kang Zhu
- China Shanghai Center for Plant Stress Biology, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 201602, China
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907
| | - Zhizhong Gong
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
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18
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Almansour K, Taverner A, Eggleston IM, Mrsny RJ. Mechanistic studies of a cell-permeant peptide designed to enhance myosin light chain phosphorylation in polarized intestinal epithelia. J Control Release 2018; 279:208-219. [PMID: 29614254 DOI: 10.1016/j.jconrel.2018.03.033] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2018] [Revised: 03/26/2018] [Accepted: 03/27/2018] [Indexed: 12/15/2022]
Abstract
Tight junction (TJ) structures restrict the movement of solutes between adjacent epithelial cells to maintain homeostatic conditions. A peptide, termed PIP 640, with the capacity to regulate the transient opening of intestinal TJ structures through an endogenous mechanism involving the induction of myosin light chain (MLC) phosphorylation at serine 19 (MLC-pS19) has provided a promising new method to enhance the in vivo oral bioavailability of peptide therapeutics. PIP 640 is a decapeptide composed of all D-amino acids (rrdykvevrr-NH2) that contains a central sequence designed to emulates a specific domain of C-kinase potentiated protein phosphatase-1 inhibitor-17 kDa (CPI-17) surrounded by positively-charged amino acids that provide a cell penetrating peptide (CPP)-like character. Here, we examine compositional requirements of PIP 640 with regard to its actions on MLC phosphorylation, its intracellular localization to TJ structures, and its interactions with MLC phosphatase (MLCP) elements that correlate with enhanced solute uptake. These studies showed that a glutamic acid and tyrosine within this peptide are critical for PIP 640 to retain its ability to increase MLC-pS19 levels and enhance the permeability of macromolecular solutes of the size range of therapeutic peptides without detectable cytotoxicity. On the other hand, exchange of the aspartic acid for alanine and then arginine resulted in an increasingly greater bias toward protein phosphatase-1 (PP1) relative to MLCP inhibition, an outcome that resulted in increased paracellular permeability for solutes in the size range of therapeutic peptides, but with a significant increase in cytotoxicity. Together, these data further our understanding of the composition requirements of PIP 640 with respect to the desired goal of transiently altering the intestinal epithelial cell paracellular barrier properties through an endogenous mechanism, providing a novel approach to enhance the oral bioavailability of poorly absorbed therapeutic agents of < ~ 5 kDa.
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Affiliation(s)
- Khaled Almansour
- Department of Pharmacy and Pharmacology, University of Bath, Bath BA2 7AY, UK
| | - Alistair Taverner
- Department of Pharmacy and Pharmacology, University of Bath, Bath BA2 7AY, UK
| | - Ian M Eggleston
- Department of Pharmacy and Pharmacology, University of Bath, Bath BA2 7AY, UK
| | - Randall J Mrsny
- Department of Pharmacy and Pharmacology, University of Bath, Bath BA2 7AY, UK.
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19
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Eto M, Kitazawa T. Diversity and plasticity in signaling pathways that regulate smooth muscle responsiveness: Paradigms and paradoxes for the myosin phosphatase, the master regulator of smooth muscle contraction. J Smooth Muscle Res 2018; 53:1-19. [PMID: 28260704 PMCID: PMC5364378 DOI: 10.1540/jsmr.53.1] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
A hallmark of smooth muscle cells is their ability to adapt their functions to meet temporal and chronic fluctuations in their demands. These functions include force development and growth. Understanding the mechanisms underlying the functional plasticity of smooth muscles, the major constituent of organ walls, is fundamental to elucidating pathophysiological rationales of failures of organ functions. Also, the knowledge is expected to facilitate devising innovative strategies that more precisely monitor and normalize organ functions by targeting individual smooth muscles. Evidence has established a current paradigm that the myosin light chain phosphatase (MLCP) is a master regulator of smooth muscle responsiveness to stimuli. Cellular MLCP activity is negatively and positively regulated in response to G-protein activation and cAMP/cGMP production, respectively, through the MYPT1 regulatory subunit and an endogenous inhibitor protein named CPI-17. In this article we review the outcomes from two decade of research on the CPI-17 signaling and discuss emerging paradoxes in the view of signaling pathways regulating smooth muscle functions through MLCP.
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Affiliation(s)
- Masumi Eto
- Department of Molecular Physiology and Biophysics, Sidney Kimmel Medical College at Thomas Jefferson University and Sidney Kimmel Cancer Center, 1020 Locust Street, Philadelphia, PA19107, USA
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20
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Protein phosphatases 1 and 2A and their naturally occurring inhibitors: current topics in smooth muscle physiology and chemical biology. J Physiol Sci 2017; 68:1-17. [PMID: 28681362 PMCID: PMC5754374 DOI: 10.1007/s12576-017-0556-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 06/27/2017] [Indexed: 12/26/2022]
Abstract
Protein phosphatases 1 and 2A (PP1 and PP2A) are the most ubiquitous and abundant serine/threonine phosphatases in eukaryotic cells. They play fundamental roles in the regulation of various cellular functions. This review focuses on recent advances in the functional studies of these enzymes in the field of smooth muscle physiology. Many naturally occurring protein phosphatase inhibitors with different relative PP1/PP2A affinities have been discovered and are widely used as powerful research tools. Current topics in the chemical biology of PP1/PP2A inhibitors are introduced and discussed, highlighting the identification of the gene cluster responsible for the biosynthesis of calyculin A in a symbiont microorganism of a marine sponge.
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21
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Filter JJ, Williams BC, Eto M, Shalloway D, Goldberg ML. Unfair competition governs the interaction of pCPI-17 with myosin phosphatase (PP1-MYPT1). eLife 2017; 6. [PMID: 28387646 PMCID: PMC5441869 DOI: 10.7554/elife.24665] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2016] [Accepted: 03/31/2017] [Indexed: 11/30/2022] Open
Abstract
The small phosphoprotein pCPI-17 inhibits myosin light-chain phosphatase (MLCP). Current models postulate that during muscle relaxation, phosphatases other than MLCP dephosphorylate and inactivate pCPI-17 to restore MLCP activity. We show here that such hypotheses are insufficient to account for the observed rapidity of pCPI-17 inactivation in mammalian smooth muscles. Instead, MLCP itself is the critical enzyme for pCPI-17 dephosphorylation. We call the mutual sequestration mechanism through which pCPI-17 and MLCP interact inhibition by unfair competition: MLCP protects pCPI-17 from other phosphatases, while pCPI-17 blocks other substrates from MLCP’s active site. MLCP dephosphorylates pCPI-17 at a slow rate that is, nonetheless, both sufficient and necessary to explain the speed of pCPI-17 dephosphorylation and the consequent MLCP activation during muscle relaxation. DOI:http://dx.doi.org/10.7554/eLife.24665.001
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Affiliation(s)
- Joshua J Filter
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, United States
| | - Byron C Williams
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, United States
| | - Masumi Eto
- Department of Molecular Physiology and Biophysics, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, United States
| | - David Shalloway
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, United States
| | - Michael L Goldberg
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, United States
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22
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Xu D, Song R, Wang G, Jeyabal PVS, Weiskoff AM, Ding K, Shi ZZ. Obg-like ATPase 1 regulates global protein serine/threonine phosphorylation in cancer cells by suppressing the GSK3β-inhibitor 2-PP1 positive feedback loop. Oncotarget 2016; 7:3427-39. [PMID: 26655089 PMCID: PMC4823117 DOI: 10.18632/oncotarget.6496] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 11/21/2015] [Indexed: 11/29/2022] Open
Abstract
OLA1 is an Obg family P-loop NTPase that possesses both GTP- and ATP-hydrolyzing activities. Here we report that OLA1 is a GSK3β interacting protein, and through its ATPase activity, inhibits the GSK3β-mediated activation of protein serine/threonine phosphatase 1 (PP1). It is hypothesized that GSK3β phosphorylates inhibitor 2 (I-2) of PP1 at Thr-72 and activates the PP1 · I-2 complex, which in turn dephosphorylates and stimulates GSK3β, thus forming a positive feedback loop. We revealed that the positive feedback loop is normally suppressed by OLA1, and becomes over-activated under OLA1 deficiency, resulting in increased cellular PP1 activity and dephosphorylation of multiple Ser/Thr phosphoproteins, and more strikingly, decreased global protein threonine phosphorylation. Furthermore, using xenograft models of colon cancer (H116) and ovarian cancer (SKOV3), we established a correlation among downregulation of OLA1, over-activation of the positive feedback loop as indicated by under-phosphorylation of I-2, and more aggressive tumor growth. This study provides the first evidence for the existence of a GSK3β-I-2-PP1 positive feedback loop in human cancer cells, and identifies OLA1 as an endogenous suppressor of this signaling motif.
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Affiliation(s)
- Dong Xu
- Department of Surgical Oncology, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310009, China
| | - Renduo Song
- Department of Translational Imaging, Houston Methodist Research Institute, Houston, TX 77030, USA
| | - Guohui Wang
- Department of Translational Imaging, Houston Methodist Research Institute, Houston, TX 77030, USA
| | - Prince V S Jeyabal
- Department of Translational Imaging, Houston Methodist Research Institute, Houston, TX 77030, USA
| | - Amanda M Weiskoff
- Department of Translational Imaging, Houston Methodist Research Institute, Houston, TX 77030, USA
| | - Kefeng Ding
- Department of Surgical Oncology, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310009, China
| | - Zheng-Zheng Shi
- Department of Translational Imaging, Houston Methodist Research Institute, Houston, TX 77030, USA
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23
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Sharma P, Arias EB, Cartee GD. Protein Phosphatase 1-α Regulates AS160 Ser588 and Thr642 Dephosphorylation in Skeletal Muscle. Diabetes 2016; 65:2606-17. [PMID: 27246912 PMCID: PMC5001182 DOI: 10.2337/db15-0867] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 05/23/2016] [Indexed: 01/09/2023]
Abstract
Akt substrate of 160 kDa (AS160) phosphorylation on Thr(642) and Ser(588) by Akt is essential for insulin's full effect on glucose transport. However, protein phosphorylation is determined by the balance of actions by kinases and phosphatases, and the specific phosphatase(s) controlling AS160 dephosphorylation is (are) unknown. Accordingly, we assessed roles of highly expressed skeletal muscle serine/threonine phosphatases (PP1, PP2A, PP2B, and PP2C) on AS160 dephosphorylation. Preliminary screening of candidate phosphatases used an AS160 dephosphorylation assay. Lysates from insulin-stimulated skeletal muscle were treated with pharmacological phosphatase inhibitors and assessed for AS160 Ser(588) and Thr(642) dephosphorylation. AS160 dephosphorylation on both phosphorylation sites was unaltered by PP2B or PP2C inhibitors. Okadaic acid (low dose inhibits PP2A; high dose inhibits PP1) delayed AS160 Ser(588) (both doses) and Thr(642) (high dose only) dephosphorylation concomitant with greater Akt phosphorylation (both doses). AS160 was coimmunoprecipitated with PP1-α but not with PP1-β, PP1-γ1, or PP2A. Recombinant inhibitor-2 protein (a selective PP1 inhibitor) delayed AS160 dephosphorylation on both phosphorylation sites without altering Akt phosphorylation. Furthermore, knockdown of PP1-α but not PP1-β or PP1-γ1 by small interfering RNA caused greater AS160 Ser(588) and Thr(642) phosphorylation concomitant with unaltered Akt phosphorylation. Together, these results identified PP1-α as a regulator of AS160 Thr(642) and Ser(588) dephosphorylation in skeletal muscle.
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Affiliation(s)
- Pragya Sharma
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, MI
| | - Edward B Arias
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, MI
| | - Gregory D Cartee
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, MI Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI Institute of Gerontology, University of Michigan, Ann Arbor, MI
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24
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Ihara E, Yu Q, Chappellaz M, MacDonald JA. ERK and p38MAPK pathways regulate myosin light chain phosphatase and contribute to Ca2+ sensitization of intestinal smooth muscle contraction. Neurogastroenterol Motil 2015; 27:135-46. [PMID: 25557225 DOI: 10.1111/nmo.12491] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Accepted: 11/20/2014] [Indexed: 12/12/2022]
Abstract
BACKGROUND Mitogen-activated protein kinases (MAPKs), including extracellular signal-regulated protein kinase (ERK) and p38MAPK, are known regulators of smooth muscle contractility. The contraction of smooth muscle is mainly regulated by the phosphorylation of regulatory light chains of myosin II (LC20), which is driven by the balance between myosin light chain kinase (MLCK) and myosin light chain phosphatase (MLCP). We hypothesized that one possible mechanism for MAPK-dependent modulation of intestinal smooth muscle contractility is via the regulation of MLCP activity. METHODS Contractile responses to carbachol (CCh) and effects of MAPK inhibitors on CCh-induced contractions were assessed with isolated rat ileal longitudinal smooth muscle strips. Biochemical assessments of MLCP activity and myosin phosphatse targeting subunit (MYPT1) and CPI-17 phosphorylations were completed. KEY RESULTS Treatment of ileal smooth muscle with PD98059 (10 μM; MEK inhibitor) or SB203580 (10 μM; p38MAPK inhibitor) significantly inhibited CCh-induced contractile force. Decreased MLCP activity was observed during sustained contractions induced by CCh; the MLCP activity was recovered by treatment with PD98059 and SB203580. However, MYPT1 (Thr697 and Thr855) and CPI-17 (Thr38) phosphorylations were not affected. Application of ML-7 (MLCK inhibitor) during CCh-induced sustained contraction elicited an MLCP-dependent relaxation, the rate of which was accelerated by application of PD98059 and SB203580 with proportional changes in LC20 phosphorylation levels but not MYPT1 phosphorylation (Thr697 or Thr855). CONCLUSIONS & INFERENCES ERK and p38MAPK contribute to CCh-induced sustained contraction in a LC20 phosphorylation dependent manner. Moreover, both kinases inhibit MLCP activity possibly by a novel mechanism.
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Affiliation(s)
- E Ihara
- Smooth Muscle Research Group at the Libin Cardiovascular Institute of Alberta, Department of Biochemistry & Molecular Biology, University of Calgary, Calgary, AB, Canada; Department of Medicine and Bioregulatory Science, Kyushu University, Higashi-ku, Fukuoka, Japan
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Eto M, Kirkbride JA, Chugh R, Karikari NK, Kim JI. Nuclear localization of CPI-17, a protein phosphatase-1 inhibitor protein, affects histone H3 phosphorylation and corresponds to proliferation of cancer and smooth muscle cells. Biochem Biophys Res Commun 2013; 434:137-42. [PMID: 23541585 DOI: 10.1016/j.bbrc.2013.03.055] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 03/17/2013] [Indexed: 01/23/2023]
Abstract
CPI-17 (C-kinase-activated protein phosphatase-1 (PP1) inhibitor, 17kDa) is a cytoplasmic protein predominantly expressed in mature smooth muscle (SM) that regulates the myosin-associated PP1 holoenzyme (MLCP). Here, we show CPI-17 expression in proliferating cells, such as pancreatic cancer and hyperplastic SM cells. Immunofluorescence showed that CPI-17 was concentrated in nuclei of human pancreatic cancer (Panc1) cells. Nuclear accumulation of CPI-17 was also detected in the proliferating vascular SM cell culture and cells at neointima of rat vascular injury model. The N-terminal 21-residue tail domain of CPI-17 was necessary for the nuclear localization. Phospho-mimetic Asp-substitution of CPI-17 at Ser12 attenuated the nuclear import. CPI-17 phosphorylated at Ser12 was not localized at nuclei, suggesting a suppressive role of Ser12 phosphorylation in the nuclear import. Activated CPI-17 bound to all three isoforms of PP1 catalytic subunit in Panc1 nuclear extracts. CPI-17 knockdown in Panc1 resulted in dephosphorylation of histone H3 at Thr3, Ser10 and Thr11, whereas it had no effects on the phosphorylation of myosin light chain and merlin, the known targets of MLCP. In parallel, CPI-17 knockdown suppressed Panc1 proliferation. We propose that CPI-17 accumulated in the nucleus through the N-terminal tail targets multiple PP1 signaling pathways regulating cell proliferation.
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Affiliation(s)
- Masumi Eto
- Department of Molecular Physiology and Biophysics, and Kimmel Cancer Center, Thomas Jefferson University, 1020 Locust Street, PA 19107, USA.
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