1
|
Osawa J, Karakawa M, Taniguchi A, Inui Y, Usuki C, Ishida A, Kameshita I, Sueyoshi N. Functional regulation of the protein phosphatase PPM1M by phosphorylation at multiple sites with Ser/Thr-Pro motifs. Arch Biochem Biophys 2024; 753:109887. [PMID: 38224862 DOI: 10.1016/j.abb.2024.109887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Revised: 12/22/2023] [Accepted: 01/09/2024] [Indexed: 01/17/2024]
Abstract
The imbalance in the phosphorylation and the dephosphorylation of proteins leads to various diseases. Therefore, in vivo, the functions of protein kinases and protein phosphatases are strictly regulated. Mg2+/Mn2+-dependent protein phosphatase PPM1M has been implicated in immunity and cancer; however, the regulation mechanism remains unknown. In this study, we show that PPM1M is regulated in different ways by multiple phosphorylation. PPM1M has four Ser/Thr-Pro motifs (Ser27, Ser43, Ser60, and Thr254) that are recognized by proline-directed kinases, and Ser60 was found to be phosphorylated by cyclin-dependent kinase 5 (CDK5) in the cell. The phospho-mimetic mutation of Ser27 and Ser43 in the N-terminal domain suppresses the nuclear localization of PPM1M and promotes its accumulation in the cytoplasm. The phospho-mimetic mutation of Ser60 decreases PPM1M activity; conversely, the phospho-mimetic mutation of Thr254 increases PPM1M activity. These results suggest that the subcellular localization and phosphatase activity of PPM1M are regulated by protein kinases, including CDK5, via phosphorylation at multiple sites. Thus, PPM1M is differentially regulated by proline-directed kinases, including CDK5.
Collapse
Affiliation(s)
- Jin Osawa
- Department of Life Sciences, Faculty of Agriculture, Kagawa University, Kagawa, 761-0795, Japan
| | - Masataka Karakawa
- Department of Life Sciences, Faculty of Agriculture, Kagawa University, Kagawa, 761-0795, Japan
| | - Aoi Taniguchi
- Department of Life Sciences, Faculty of Agriculture, Kagawa University, Kagawa, 761-0795, Japan
| | - Yuiko Inui
- Department of Life Sciences, Faculty of Agriculture, Kagawa University, Kagawa, 761-0795, Japan
| | - Chika Usuki
- Department of Life Sciences, Faculty of Agriculture, Kagawa University, Kagawa, 761-0795, Japan
| | - Atsuhiko Ishida
- Laboratory of Molecular Brain Science, Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, 739-8521, Japan.
| | - Isamu Kameshita
- Department of Life Sciences, Faculty of Agriculture, Kagawa University, Kagawa, 761-0795, Japan
| | - Noriyuki Sueyoshi
- Department of Life Sciences, Faculty of Agriculture, Kagawa University, Kagawa, 761-0795, Japan.
| |
Collapse
|
2
|
Ma Y, Wei J, Song J, Hu Z, Zhang R, Li Z, Sun Y. The DACH1 Gene Transcriptional Activation and Protein Degradation Mediated by Transactivator Tas of Prototype Foamy Virus. Viruses 2023; 15:1899. [PMID: 37766305 PMCID: PMC10534306 DOI: 10.3390/v15091899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 09/02/2023] [Accepted: 09/06/2023] [Indexed: 09/29/2023] Open
Abstract
Foamy viruses are members of the Retroviridae family's Spumaretrovirinae subfamily. They induce cell vacuolation and exhibit a foamy pathogenic impact after infecting cells. DACH1 (dachshund family transcription factor 1) is a crucial cytokine linked to tumor development, and is associated with the growth of many different malignant tumor cells. Additionally, DACH1 suppresses pancreatic cell proliferation and is involved in diabetes insulin signaling. Prototype foamy viruses (PFVs) were used for the investigation of the regulatory mechanism of FVs on cellular DACH1 expression. The results show that DACH1 expression in PFV-infected cells was inconsistent at both the transcriptional and protein levels. At the transcriptional level, DACH1 was significantly activated by PFV transactivator Tas, and dual-luciferase reporter gene tests, EMSA, and ChIP assays found a Tas response element of 21 nucleotides in the DACH1 promoter. PFV and Tas did not boost the levels of DACH1 protein in a manner consistent with the high levels of DACH1 transcription expression. It was noted that Tas increased the expression of the Ser/Thr protein phosphatase PPM1E, causing PPM1E-mediated post-translational SUMOylation alterations of DACH1 to prompt DACH1 to degrade. The reason for DACH1 protein degradation is that DACH1 inhibits PFV replication. To sum up, these findings show that PFV upregulated the transcription of DACH1, while urging its protein into PPM1E-mediated SUMOylation, to eliminate the adverse effect of DACH1 overexpression of host cells on viral replication and promote virus survival.
Collapse
Affiliation(s)
- Yongping Ma
- College of Life Science, Shaanxi Normal University, Xi’an 710119, China
- College of Biological Science and Engineering, North Minzu University, Yinchuan 750021, China
| | - Jie Wei
- College of Life Science, Shaanxi Normal University, Xi’an 710119, China
- College of Environment and Life Sciences, Weinan Normal University, Weinan 714099, China
| | - Jing Song
- College of Life Science, Shaanxi Normal University, Xi’an 710119, China
| | - Zhongxiang Hu
- College of Life Science, Shaanxi Normal University, Xi’an 710119, China
| | - Ruifen Zhang
- College of Life Science, Shaanxi Normal University, Xi’an 710119, China
| | - Zhi Li
- College of Life Science, Shaanxi Normal University, Xi’an 710119, China
| | - Yan Sun
- College of Life Science, Shaanxi Normal University, Xi’an 710119, China
| |
Collapse
|
3
|
Gheibi S, Cataldo LR, Hamilton A, Huang M, Kalamajski S, Fex M, Mulder H. Reduced Expression Level of Protein Phosphatase PPM1E Serves to Maintain Insulin Secretion in Type 2 Diabetes. Diabetes 2023; 72:455-466. [PMID: 36662636 DOI: 10.2337/db22-0472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2022] [Accepted: 01/12/2023] [Indexed: 01/21/2023]
Abstract
Reversible phosphorylation is an important regulatory mechanism. Regulation of protein phosphorylation in β-cells has been extensively investigated, but less is known about protein dephosphorylation. To understand the role of protein dephosphorylation in β-cells and type 2 diabetes (T2D), we first examined mRNA expression of the type 2C family (PP2C) of protein phosphatases in islets from T2D donors. Phosphatase expression overall was changed in T2D, and that of PPM1E was the most markedly downregulated. PPM1E expression correlated inversely with HbA1c. Silencing of PPM1E increased glucose-stimulated insulin secretion (GSIS) in INS-1 832/13 cells and/or islets from patients with T2D, whereas PPM1E overexpression decreased GSIS. Increased GSIS after PPM1E silencing was associated with decreased oxidative stress, elevated cytosolic Ca2+ levels and ATP to ADP ratio, increased hyperpolarization of the inner mitochondrial membrane, and phosphorylation of CaMKII, AMPK, and acetyl-CoA carboxylase. Silencing of PPM1E, however, did not change insulin content. Increased GSIS, cell viability, and activation of AMPK upon metformin treatment in β-cells were observed upon PPM1E silencing. Thus, protein dephosphorylation via PPM1E abrogates GSIS. Consequently, reduced PPM1E expression in T2D may be a compensatory response of β-cells to uphold insulin secretion under metabolic duress. Targeting PPM1E in β-cells may thus represent a novel therapeutic strategy for treatment of T2D.
Collapse
Affiliation(s)
- Sevda Gheibi
- Unit of Molecular Metabolism, Lund University Diabetes Centre, Malmö, Sweden
| | - Luis Rodrigo Cataldo
- Unit of Molecular Metabolism, Lund University Diabetes Centre, Malmö, Sweden
- The Novo Nordisk Foundation Centre for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Alexander Hamilton
- Unit of Islet Cell Exocytosis, Lund University Diabetes Centre, Malmö, Sweden
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Mi Huang
- Department of Clinical Sciences, Genetic and Molecular Epidemiology Unit, Lund University, Malmö, Sweden
| | - Sebastian Kalamajski
- Department of Clinical Sciences, Genetic and Molecular Epidemiology Unit, Lund University, Malmö, Sweden
| | - Malin Fex
- Unit of Molecular Metabolism, Lund University Diabetes Centre, Malmö, Sweden
| | - Hindrik Mulder
- Unit of Molecular Metabolism, Lund University Diabetes Centre, Malmö, Sweden
| |
Collapse
|
4
|
Metal-dependent Ser/Thr protein phosphatase PPM family: Evolution, structures, diseases and inhibitors. Pharmacol Ther 2020; 215:107622. [PMID: 32650009 DOI: 10.1016/j.pharmthera.2020.107622] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 06/29/2020] [Indexed: 02/06/2023]
Abstract
Protein phosphatases and kinases control multiple cellular events including proliferation, differentiation, and stress responses through regulating reversible protein phosphorylation, the most important post-translational modification. Members of metal-dependent protein phosphatase (PPM) family, also known as PP2C phosphatases, are Ser/Thr phosphatases that bind manganese/magnesium ions (Mn2+/Mg2+) in their active center and function as single subunit enzymes. In mammals, there are 20 isoforms of PPM phosphatases: PPM1A, PPM1B, PPM1D, PPM1E, PPM1F, PPM1G, PPM1H, PPM1J, PPM1K, PPM1L, PPM1M, PPM1N, ILKAP, PDP1, PDP2, PHLPP1, PHLPP2, PP2D1, PPTC7, and TAB1, whereas there are only 8 in yeast. Phylogenetic analysis of the DNA sequences of vertebrate PPM isoforms revealed that they can be divided into 12 different classes: PPM1A/PPM1B/PPM1N, PPM1D, PPM1E/PPM1F, PPM1G, PPM1H/PPM1J/PPM1M, PPM1K, PPM1L, ILKAP, PDP1/PDP2, PP2D1/PHLPP1/PHLPP2, TAB1, and PPTC7. PPM-family members have a conserved catalytic core region, which contains the metal-chelating residues. The different isoforms also have isoform specific regions within their catalytic core domain and terminal domains, and these regions may be involved in substrate recognition and/or functional regulation of the phosphatases. The twenty mammalian PPM phosphatases are involved in regulating diverse cellular functions, such as cell cycle control, cell differentiation, immune responses, and cell metabolism. Mutation, overexpression, or deletion of the PPM phosphatase gene results in abnormal cellular responses, which lead to various human diseases. This review focuses on the structures and biological functions of the PPM-phosphatase family and their associated diseases. The development of specific inhibitors against the PPM phosphatase family as a therapeutic strategy will also be discussed.
Collapse
|
5
|
Osawa J, Akizuki K, Kashimura A, Ueta S, Nakatani M, Inui Y, Shigeri Y, Ishida A, Kameshita I, Sueyoshi N. Dual phosphorylation of protein phosphatase PPM1H promotes dephosphorylation of Smad1 in cellulo. Biochem Biophys Res Commun 2020; 530:513-519. [PMID: 32600616 DOI: 10.1016/j.bbrc.2020.05.082] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 05/13/2020] [Indexed: 01/08/2023]
Abstract
Protein phosphatase PPM1H is known to participate in various biological or pathophysiological mechanisms. However, little is known about the molecular mechanisms of its regulation. In this study, we investigated the protein kinases that directly phosphorylate PPM1H, identifying them as cAMP-dependent protein kinase (PKA) and Ca2+/calmodulin-dependent protein kinase I (CaMKI). In vitro and in silico analyses showed that the phosphorylation sites of PPM1H by PKA and CaMKI were Ser-123 and Ser-210, respectively. The phosphorylation state of PPM1H in cells exhibited the kinase activator- and inhibitor-dependent changes. In mouse neuroblastoma Neuro2a cells, phosphorylation of Ser-210 was much higher in the phospho-mimetic mutant (S123D) than in the non-phosphorylatable mutant (S123A) when they were treated with ionomycin. This suggests that a hierarchical phosphorylation, with initial phosphorylation of Ser-123 promoting subsequent phosphorylation of Ser-210, occurs in these neuron-like cells. Moreover, in cell-based assay a PPM1H(S123A/S210A) double mutant barely dephosphorylated Smad1, a transcription factor known as an endogenous substrate of PPM1H. These results suggest that cAMP and Ca2+/calmodulin regulate dephosphorylation of Smad1 through the dual phosphorylation of PPM1H at Ser-123 and Ser-210.
Collapse
Affiliation(s)
- Jin Osawa
- Department of Life Sciences, Faculty of Agriculture, Kagawa University, Kagawa, 761-0795, Japan
| | - Kazutoshi Akizuki
- Department of Life Sciences, Faculty of Agriculture, Kagawa University, Kagawa, 761-0795, Japan; Laboratory of Molecular Brain Science, Graduate School of Integrated Arts and Sciences, Hiroshima University, Higashi-Hiroshima, 739-8521, Japan
| | - Akari Kashimura
- Department of Life Sciences, Faculty of Agriculture, Kagawa University, Kagawa, 761-0795, Japan
| | - Saki Ueta
- Department of Life Sciences, Faculty of Agriculture, Kagawa University, Kagawa, 761-0795, Japan
| | - Misato Nakatani
- Department of Life Sciences, Faculty of Agriculture, Kagawa University, Kagawa, 761-0795, Japan
| | - Yuiko Inui
- Department of Life Sciences, Faculty of Agriculture, Kagawa University, Kagawa, 761-0795, Japan
| | - Yasushi Shigeri
- Department of Chemistry, Wakayama Medical University, 580 Mikazura, Wakayama, 641-0011, Japan
| | - Atsuhiko Ishida
- Laboratory of Molecular Brain Science, Graduate School of Integrated Arts and Sciences, Hiroshima University, Higashi-Hiroshima, 739-8521, Japan.
| | - Isamu Kameshita
- Department of Life Sciences, Faculty of Agriculture, Kagawa University, Kagawa, 761-0795, Japan
| | - Noriyuki Sueyoshi
- Department of Life Sciences, Faculty of Agriculture, Kagawa University, Kagawa, 761-0795, Japan.
| |
Collapse
|
6
|
Functions and dysfunctions of Ca2+/calmodulin-dependent protein kinase phosphatase (CaMKP/PPM1F) and CaMKP-N/PPM1E. Arch Biochem Biophys 2018; 640:83-92. [DOI: 10.1016/j.abb.2018.01.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 12/28/2017] [Accepted: 01/04/2018] [Indexed: 12/22/2022]
|
7
|
Onouchi T, Kishino-Kaneko Y, Kameshita I, Ishida A, Sueyoshi N. Regulation of Ca(2+)/calmodulin-dependent protein kinase phosphatase (CaMKP/PPM1F) by protocadherin-γC5 (Pcdh-γC5). Arch Biochem Biophys 2015; 585:109-120. [PMID: 26386307 DOI: 10.1016/j.abb.2015.09.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Revised: 09/15/2015] [Accepted: 09/15/2015] [Indexed: 01/14/2023]
Abstract
Ca(2+)/calmodulin-dependent protein kinase phosphatase (CaMKP/PPM1F) is a Ser/Thr protein phosphatase that belongs to the PPM family. It is important to identify an endogenous regulator of CaMKP. Using an Escherichia coli two-hybrid screening method, we identified the C-terminal cytoplasmic fragment of protocadherin γ subfamily C5 (Pcdh-γC5), which was generated by intracellular processing, as a CaMKP-binding protein. Dephosphorylation of phosphorylated Ca(2+)/calmodulin-dependent protein kinase I (CaMKI) by CaMKP was significantly activated by the C-terminal cytoplasmic fragment, Pcdh-γC5(715-944), both in vitro and in cells, suggesting that the C-terminal fragment functions as an endogenous activator of CaMKP. The nuclear translocation of the fragment was blocked by its binding to cytoplasmic CaMKP to form a ternary complex with CaMKI. Taken together, these results strongly suggest that the C-terminal cytoplasmic fragment of Pcdh-γC5 acts as a scaffold for CaMKP and CaMKI to regulate CaMKP activity. These findings may provide new insights into the reversible regulation of CaMKP in cells.
Collapse
Affiliation(s)
- Takashi Onouchi
- Department of Life Sciences, Faculty of Agriculture, Kagawa University, Kagawa 761-0795, Japan
| | - Yoshimi Kishino-Kaneko
- Department of Life Sciences, Faculty of Agriculture, Kagawa University, Kagawa 761-0795, Japan
| | - Isamu Kameshita
- Department of Life Sciences, Faculty of Agriculture, Kagawa University, Kagawa 761-0795, Japan
| | - Atsuhiko Ishida
- Laboratory of Molecular Brain Science, Graduate School of Integrated Arts and Sciences, Hiroshima University, Higashi-Hiroshima 739-8521, Japan.
| | - Noriyuki Sueyoshi
- Department of Life Sciences, Faculty of Agriculture, Kagawa University, Kagawa 761-0795, Japan.
| |
Collapse
|
8
|
The Phosphatase-Resistant Isoform of CaMKI, Ca²⁺/Calmodulin-Dependent Protein Kinase Iδ (CaMKIδ), Remains in Its "Primed" Form without Ca²⁺ Stimulation. Biochemistry 2015; 54:3617-30. [PMID: 25994484 DOI: 10.1021/bi5012139] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Ca²⁺/calmodulin-dependent protein kinase I (CaMKI) is known to play pivotal roles in Ca²⁺ signaling pathways. Four isoforms of CaMKI (α, β, γ, and δ) have been reported so far. CaMKI is activated through phosphorylation by the upstream kinase, CaMK kinase (CaMKK), and phosphorylates downstream targets. When CaMKI was transiently expressed in 293T cells, CaMKIα was not phosphorylated at all under low-Ca²⁺ conditions in the cells. In contrast, we found that CaMKIδ was significantly phosphorylated and activated to phosphorylate cAMP response element-binding protein (CREB) under the same conditions. Herein, we report that the sustained activation of CaMKIδ is ascribed to its phosphatase resistance resulting from the structure of its N-terminal region. First, we examined whether CaMKIδ is more readily phosphorylated by CaMKK than CaMKIα, but no significant difference was observed. Next, to compare the phosphatase resistance between CaMKIα and CaMKIδ, we assessed the dephosphorylation of the phosphorylated CaMKIs by CaMK phosphatase (CaMKP/PPM1F). Surprisingly, CaMKIδ was hardly dephosphorylated by CaMKP, whereas CaMKIα was significantly dephosphorylated under the same conditions. To date, there have been no detailed reports concerning dephosphorylation of CaMKI. Through extensive analysis of CaMKP-catalyzed dephosphorylation of various chimeric and point mutants of CaMKIδ and CaMKIα, we identified the amino acid residues responsible for the phosphatase resistance of CaMKIδ (Pro-57, Lys-62, Ser-66, Ile-68, and Arg-76). These results also indicate that the phosphatase resistance of CaMKI is largely affected by only several amino acids in its N-terminal region. The phosphatase-resistant CaMKI isoform may play a physiological role under low-Ca²⁺ conditions in the cells.
Collapse
|
9
|
Berchtold MW, Villalobo A. The many faces of calmodulin in cell proliferation, programmed cell death, autophagy, and cancer. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1843:398-435. [PMID: 24188867 DOI: 10.1016/j.bbamcr.2013.10.021] [Citation(s) in RCA: 230] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2013] [Revised: 10/24/2013] [Accepted: 10/26/2013] [Indexed: 12/21/2022]
Abstract
Calmodulin (CaM) is a ubiquitous Ca(2+) receptor protein mediating a large number of signaling processes in all eukaryotic cells. CaM plays a central role in regulating a myriad of cellular functions via interaction with multiple target proteins. This review focuses on the action of CaM and CaM-dependent signaling systems in the control of vertebrate cell proliferation, programmed cell death and autophagy. The significance of CaM and interconnected CaM-regulated systems for the physiology of cancer cells including tumor stem cells, and processes required for tumor progression such as growth, tumor-associated angiogenesis and metastasis are highlighted. Furthermore, the potential targeting of CaM-dependent signaling processes for therapeutic use is discussed.
Collapse
Key Words
- (4-[3,5-bis-[2-(4-hydroxy-3-methoxy-phenyl)-ethyl]-4,5-dihydro-pyrazol-1-yl]-benzoic acid
- (4-[3,5-bis-[2-(4-hydroxy-3-methoxy-phenyl)-vinyl]-4,5-dihydro-pyrazol-1-yl]-phenyl)-(4-methyl-piperazin-1-yl)-methanone
- (−) enantiomer of dihydropyrine 3-methyl-5-3-(4,4-diphenyl-1-piperidinyl)-propyl-1,4-dihydro-2,6-dimethyl-4-(3-nitrophenyl)-piridine-3,5-dicarboxylate-hydrochloride (niguldipine)
- 1-[N,O-bis(5-isoquinolinesulfonyl)-N-methyl-l-tyrosyl]-4-phenylpiperazine
- 12-O-tetradecanoyl-phorbol-13-acetate
- 2-chloro-(ε-amino-Lys(75))-[6-(4-(N,N′-diethylaminophenyl)-1,3,5-triazin-4-yl]-CaM adduct
- 3′-(β-chloroethyl)-2′,4′-dioxo-3,5′-spiro-oxazolidino-4-deacetoxy-vinblastine
- 7,12-dimethylbenz[a]anthracene
- Apoptosis
- Autophagy
- B859-35
- CAPP(1)-CaM
- Ca(2+) binding protein
- Calmodulin
- Cancer biology
- Cell proliferation
- DMBA
- EBB
- FL-CaM
- FPCE
- HBC
- HBCP
- J-8
- KAR-2
- KN-62
- KN-93
- N-(4-aminobutyl)-2-naphthalenesulfonamide
- N-(4-aminobutyl)-5-chloro-2-naphthalenesulfonamide
- N-(6-aminohexyl)-1-naphthalenesulfonamide
- N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide
- N-8-aminooctyl-5-iodo-naphthalenesulfonamide
- N-[2-[N-(4-chlorocinnamyl)-N-methylaminomethyl]phenyl]-N-(2-hydroxyethyl)-4-methoxybenzenesulfonamide
- O-(4-ethoxyl-butyl)-berbamine
- RITC-CaM
- TA-CaM
- TFP
- TPA
- W-12
- W-13
- W-5
- W-7
- fluorescein-CaM adduct
- fluphenazine-N-2-chloroethane
- norchlorpromazine-CaM adduct
- rhodamine isothiocyanate-CaM adduct
- trifluoperazine
Collapse
Affiliation(s)
- Martin W Berchtold
- Department of Biology, University of Copenhagen, Copenhagen Biocenter 4-2-09 Ole Maaløes Vej 5, DK-2200 Copenhagen N, Denmark.
| | - Antonio Villalobo
- Instituto de Investigaciones Biomédicas, Department of Cancer Biology, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, c/Arturo Duperier 4, E-28029 Madrid, Spain.
| |
Collapse
|
10
|
An active C-terminally truncated form of Ca (2+) /calmodulin-dependent protein kinase phosphatase-N (CaMKP-N/PPM1E). BIOMED RESEARCH INTERNATIONAL 2013; 2013:134813. [PMID: 23991411 PMCID: PMC3749536 DOI: 10.1155/2013/134813] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Revised: 07/10/2013] [Accepted: 07/12/2013] [Indexed: 11/17/2022]
Abstract
Ca2+/calmodulin-dependent protein kinase phosphatase (CaMKP/PPM1F) and its nuclear homolog CaMKP-N (PPM1E) are Ser/Thr protein phosphatases that belong to the PPM family. CaMKP-N is expressed in the brain and undergoes proteolytic processing to yield a C-terminally truncated form. The physiological significance of this processing, however, is not fully understood. Using a wheat-embryo cell-free protein expression system, we prepared human CaMKP-N (hCaMKP-N(WT)) and the truncated form, hCaMKP-N(1–559), to compare their enzymatic properties using a phosphopeptide substrate. The hCaMKP-N(1–559) exhibited a much higher Vmax value than the hCaMKP-N(WT) did, suggesting that the processing may be a regulatory mechanism to generate a more active species. The active form, hCaMKP-N(1–559), showed Mn2+ or Mg2+-dependent phosphatase activity with a strong preference for phospho-Thr residues and was severely inhibited by NaF, but not by okadaic acid, calyculin A, or 1-amino-8-naphthol-2,4-disulfonic acid, a specific inhibitor of CaMKP. It could bind to postsynaptic density and dephosphorylate the autophosphorylated Ca2+/calmodulin-dependent protein kinase II. Furthermore, it was inactivated by H2O2 treatment, and the inactivation was completely reversed by treatment with DTT, implying that this process is reversibly regulated by oxidation/reduction. The truncated CaMKP-N may play an important physiological role in neuronal cells.
Collapse
|