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Shekar A, Mabry SJ, Cheng MH, Aguilar JI, Patel S, Zanella D, Saleeby DP, Zhu Y, Romanazzi T, Ulery-Reynolds P, Bahar I, Carter AM, Matthies HJG, Galli A. Syntaxin 1 Ser 14 phosphorylation is required for nonvesicular dopamine release. SCIENCE ADVANCES 2023; 9:eadd8417. [PMID: 36630507 PMCID: PMC9833662 DOI: 10.1126/sciadv.add8417] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 12/14/2022] [Indexed: 05/30/2023]
Abstract
Amphetamine (AMPH) is a psychostimulant that is commonly abused. The stimulant properties of AMPH are associated with its ability to increase dopamine (DA) neurotransmission. This increase is promoted by nonvesicular DA release mediated by reversal of DA transporter (DAT) function. Syntaxin 1 (Stx1) is a SNARE protein that is phosphorylated at Ser14 by casein kinase II. We show that Stx1 phosphorylation is critical for AMPH-induced nonvesicular DA release and, in Drosophila melanogaster, regulates the expression of AMPH-induced preference and sexual motivation. Our molecular dynamics simulations of the DAT/Stx1 complex demonstrate that phosphorylation of these proteins is pivotal for DAT to dwell in a DA releasing state. This state is characterized by the breakdown of two key salt bridges within the DAT intracellular gate, causing the opening and hydration of the DAT intracellular vestibule, allowing DA to bind from the cytosol, a mechanism that we hypothesize underlies nonvesicular DA release.
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Affiliation(s)
- Aparna Shekar
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Samuel J. Mabry
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Mary H. Cheng
- Department of Computational and Systems Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Jenny I. Aguilar
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Shalin Patel
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Daniele Zanella
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
| | - David P. Saleeby
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Yanqi Zhu
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Tiziana Romanazzi
- Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy
| | | | - Ivet Bahar
- Department of Computational and Systems Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Angela M. Carter
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
| | | | - Aurelio Galli
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
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Barak-Broner N, Singer-Lahat D, Chikvashvili D, Lotan I. CK2 Phosphorylation Is Required for Regulation of Syntaxin 1A Activity in Ca 2+-Triggered Release in Neuroendocrine Cells. Int J Mol Sci 2021; 22:ijms222413556. [PMID: 34948351 PMCID: PMC8708312 DOI: 10.3390/ijms222413556] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 12/12/2021] [Accepted: 12/13/2021] [Indexed: 12/29/2022] Open
Abstract
The polybasic juxtamembrane region (5RK) of the plasma membrane neuronal SNARE, syntaxin1A (Syx), was previously shown by us to act as a fusion clamp in PC12 cells, as charge neutralization of 5RK promotes spontaneous and inhibits Ca2+-triggered release. Using a Syx-based FRET probe (CSYS), we demonstrated that 5RK is required for a depolarization-induced Ca+2-dependent opening (close-to-open transition; CDO) of Syx, which involves the vesicular SNARE synaptobrevin2 and occurs concomitantly with Ca2+-triggered release. Here, we investigated the mechanism underlying the CDO requirement for 5RK and identified phosphorylation of Syx at Ser-14 (S14) by casein kinase 2 (CK2) as a crucial molecular determinant. Thus, following biochemical verification that both endogenous Syx and CSYS are constitutively S14 phosphorylated in PC12 cells, dynamic FRET analysis of phospho-null and phospho-mimetic mutants of CSYS and the use of a CK2 inhibitor revealed that the S14 phosphorylation confers the CDO requirement for 5RK. In accord, amperometric analysis of catecholamine release revealed that the phospho-null mutant does not support Ca2+-triggered release. These results identify a functionally important CK2 phosphorylation of Syx that is required for the 5RK-regulation of CDO and for concomitant Ca2+-triggered release. Further, also spontaneous release, conferred by charge neutralization of 5RK, was abolished in the phospho-null mutant.
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Affiliation(s)
- Noa Barak-Broner
- Department of Neurobiology Biochemistry & Biophysics, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Tel Aviv-Yafo 69978, Israel;
| | - Dafna Singer-Lahat
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Ramat Aviv, Tel Aviv-Yafo 69978, Israel; (D.S.-L.); (D.C.)
| | - Dodo Chikvashvili
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Ramat Aviv, Tel Aviv-Yafo 69978, Israel; (D.S.-L.); (D.C.)
| | - Ilana Lotan
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Ramat Aviv, Tel Aviv-Yafo 69978, Israel; (D.S.-L.); (D.C.)
- Sagol School of Neuroscience, Tel Aviv University, Ramat Aviv, Tel Aviv-Yafo 69978, Israel
- Correspondence:
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3
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Silbern I, Pan KT, Fiosins M, Bonn S, Rizzoli SO, Fornasiero EF, Urlaub H, Jahn R. Protein Phosphorylation in Depolarized Synaptosomes: Dissecting Primary Effects of Calcium from Synaptic Vesicle Cycling. Mol Cell Proteomics 2021; 20:100061. [PMID: 33582301 PMCID: PMC7995663 DOI: 10.1016/j.mcpro.2021.100061] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 02/02/2021] [Indexed: 01/20/2023] Open
Abstract
Synaptic transmission is mediated by the regulated exocytosis of synaptic vesicles. When the presynaptic membrane is depolarized by an incoming action potential, voltage-gated calcium channels open, resulting in the influx of calcium ions that triggers the fusion of synaptic vesicles (SVs) with the plasma membrane. SVs are recycled by endocytosis. Phosphorylation of synaptic proteins plays a major role in these processes, and several studies have shown that the synaptic phosphoproteome changes rapidly in response to depolarization. However, it is unclear which of these changes are directly linked to SV cycling and which might regulate other presynaptic functions that are also controlled by calcium-dependent kinases and phosphatases. To address this question, we analyzed changes in the phosphoproteome using rat synaptosomes in which exocytosis was blocked with botulinum neurotoxins (BoNTs) while depolarization-induced calcium influx remained unchanged. BoNT-treatment significantly alters the response of the synaptic phoshoproteome to depolarization and results in reduced phosphorylation levels when compared with stimulation of synaptosomes by depolarization with KCl alone. We dissect the primary Ca2+-dependent phosphorylation from SV-cycling-dependent phosphorylation and confirm an effect of such SV-cycling-dependent phosphorylation events on syntaxin-1a-T21/T23, synaptobrevin-S75, and cannabinoid receptor-1-S314/T322 on exo- and endocytosis in cultured hippocampal neurons.
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Affiliation(s)
- Ivan Silbern
- Institute of Clinical Chemistry, University Medical Center Goettingen, Goettingen, Germany; Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Goettingen, Germany
| | - Kuan-Ting Pan
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Goettingen, Germany
| | - Maksims Fiosins
- German Center for Neurodegenerative Diseases, Tübingen, Germany; Institute for Medical Systems Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Stefan Bonn
- German Center for Neurodegenerative Diseases, Tübingen, Germany; Institute for Medical Systems Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Silvio O Rizzoli
- Department of Neuro- and Sensory Physiology, University Medical Center Göttingen, Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Goettingen, Göttingen, Germany
| | - Eugenio F Fornasiero
- Department of Neuro- and Sensory Physiology, University Medical Center Göttingen, Göttingen, Germany.
| | - Henning Urlaub
- Institute of Clinical Chemistry, University Medical Center Goettingen, Goettingen, Germany; Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Goettingen, Germany.
| | - Reinhard Jahn
- Laboratory of Neurobiology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.
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4
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Diverse exocytic pathways for mast cell mediators. Biochem Soc Trans 2018; 46:235-247. [PMID: 29472369 DOI: 10.1042/bst20170450] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Revised: 12/23/2017] [Accepted: 01/04/2018] [Indexed: 12/14/2022]
Abstract
Mast cells play pivotal roles in innate and adaptive immunities but are also culprits in allergy, autoimmunity, and cardiovascular diseases. Mast cells respond to environmental changes by initiating regulated exocytosis/secretion of various biologically active compounds called mediators (e.g. proteases, amines, and cytokines). Many of these mediators are stored in granules/lysosomes and rely on intricate degranulation processes for release. Mast cell stabilizers (e.g. sodium cromoglicate), which prevent such degranulation processes, have therefore been clinically employed to treat asthma and allergic rhinitis. However, it has become increasingly clear that different mast cell diseases often involve multiple mediators that rely on overlapping but distinct mechanisms for release. This review illustrates existing evidence that highlights the diverse exocytic pathways in mast cells. We also discuss strategies to delineate these pathways so as to identify unique molecular components which could serve as new drug targets for more effective and specific treatments against mast cell-related diseases.
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Gao J, Hirata M, Mizokami A, Zhao J, Takahashi I, Takeuchi H, Hirata M. Differential role of SNAP-25 phosphorylation by protein kinases A and C in the regulation of SNARE complex formation and exocytosis in PC12 cells. Cell Signal 2015; 28:425-437. [PMID: 26721188 DOI: 10.1016/j.cellsig.2015.12.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2015] [Revised: 12/15/2015] [Accepted: 12/21/2015] [Indexed: 11/30/2022]
Abstract
The final step of regulated exocytosis, membrane fusion, is mediated by formation of the SNARE complex by syntaxin, SNAP-25 (synaptosomal-associated protein of 25 kDa), and VAMP (vesicle-associated membrane protein). Phosphorylation of SNARE and accessory proteins contributes to regulation of exocytosis. We previously identified residues of SNAP-25 phosphorylated by protein kinase A (PKA) and PKC. However, the physiological role of SNAP-25 phosphorylation in exocytosis, in particular with regard to SNARE complex formation, has remained elusive. SNARE complex formation by purified recombinant SNAP-25, syntaxin-1, and VAMP-2 in vitro was inhibited or promoted as a result of the phosphorylation at Thr(138) by PKA or at Ser(187) by PKC, respectively. SNARE complex formation in intact PC12 cells was similarly inhibited by forskolin (activator of PKA) and promoted by phorbol 12-myristate 13-acetate (PMA, activator of PKC). Noradrenaline secretion from PC12 cells induced by a high K(+) concentration was enhanced by forskolin or PMA. Stable depletion of SNAP-25 inhibited high-K(+)-induced noradrenaline secretion. Forced expression of WT SNAP-25 restored the secretory response of the SNAP-25-depleted cells to high-K(+), and this response was enhanced by forskolin or PMA. Expression of the nonphosphorylatable T138A or S187A mutants of SNAP-25 similarly rescued the secretory response to high-K(+), but the augmentation of this response by forskolin was more pronounced in the cells expressing SNAP-25 (T138A) than in those expressing SNAP-25 (WT), whereas that by PMA was less pronounced in those expressing SNAP-25 (S187A). Our results thus suggest that SNAP-25 phosphorylation by PKA or PKC contributes differentially to the control of exocytosis in PC12 cells by regulating SNARE complex formation.
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Affiliation(s)
- Jing Gao
- Laboratory of Molecular and Cellular Biochemistry, Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Makiko Hirata
- Laboratory of Molecular and Cellular Biochemistry, Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan; Section of Orthodontics, Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Akiko Mizokami
- Laboratory of Molecular and Cellular Biochemistry, Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Jin Zhao
- Laboratory of Molecular and Cellular Biochemistry, Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Ichiro Takahashi
- Section of Orthodontics, Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Hiroshi Takeuchi
- Division of Applied Pharmacology, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu 803-8580, Japan
| | - Masato Hirata
- Laboratory of Molecular and Cellular Biochemistry, Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
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6
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Cartier E, Hamilton PJ, Belovich AN, Shekar A, Campbell NG, Saunders C, Andreassen TF, Gether U, Veenstra-Vanderweele J, Sutcliffe JS, Ulery-Reynolds PG, Erreger K, Matthies HJG, Galli A. Rare autism-associated variants implicate syntaxin 1 (STX1 R26Q) phosphorylation and the dopamine transporter (hDAT R51W) in dopamine neurotransmission and behaviors. EBioMedicine 2015; 2:135-146. [PMID: 25774383 PMCID: PMC4353922 DOI: 10.1016/j.ebiom.2015.01.007] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Background Syntaxin 1 (STX1) is a presynaptic plasma membrane protein that coordinates synaptic vesicle fusion. STX1 also regulates the function of neurotransmitter transporters, including the dopamine (DA) transporter (DAT). The DAT is a membrane protein that controls DA homeostasis through the high-affinity re-uptake of synaptically released DA. Methods We adopt newly developed animal models and state-of-the-art biophysical techniques to determine the contribution of the identified gene variants to impairments in DA neurotransmission observed in autism spectrum disorder (ASD). Outcomes Here, we characterize two independent autism-associated variants in the genes that encode STX1 and the DAT. We demonstrate that each variant dramatically alters DAT function. We identify molecular mechanisms that converge to inhibit reverse transport of DA and DA-associated behaviors. These mechanisms involve decreased phosphorylation of STX1 at Ser14 mediated by casein kinase 2 as well as a reduction in STX1/DAT interaction. These findings point to STX1/DAT interactions and STX1 phosphorylation as key regulators of DA homeostasis. Interpretation We determine the molecular identity and the impact of these variants with the intent of defining DA dysfunction and associated behaviors as possible complications of ASD. We report two independent autism-associated variants in syntaxin and the dopamine transporter. The variants in syntaxin and dopamine transporter each impair reverse transport of dopamine. Dysregulation of dopamine neurotransmission may represent a complication of autism spectrum disorder.
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Affiliation(s)
- Etienne Cartier
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232-8548, United States
| | - Peter J Hamilton
- Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, TN 37232-8548, United States ; Neuroscience Program in Substance Abuse, Vanderbilt University School of Medicine, Nashville, TN 37232-8548, United States
| | - Andrea N Belovich
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232-8548, United States
| | - Aparna Shekar
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232-8548, United States
| | - Nicholas G Campbell
- Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, TN 37232-8548, United States
| | - Christine Saunders
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232-8548, United States
| | - Thorvald F Andreassen
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Ulrik Gether
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Jeremy Veenstra-Vanderweele
- Department of Psychiatry and New York State Psychiatric Institute, Columbia University, New York, NY, 10032 USA
| | - James S Sutcliffe
- Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, TN 37232-8548, United States ; Department of Psychiatry, Vanderbilt University School of Medicine, Nashville, TN 37232-8548, United States
| | - Paula G Ulery-Reynolds
- Department of Psychiatry, UT Southwestern Medical Center, Dallas TX 75390-8813, United States
| | - Kevin Erreger
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232-8548, United States ; Neuroscience Program in Substance Abuse, Vanderbilt University School of Medicine, Nashville, TN 37232-8548, United States
| | - Heinrich J G Matthies
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232-8548, United States ; Neuroscience Program in Substance Abuse, Vanderbilt University School of Medicine, Nashville, TN 37232-8548, United States
| | - Aurelio Galli
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232-8548, United States ; Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, TN 37232-8548, United States ; Neuroscience Program in Substance Abuse, Vanderbilt University School of Medicine, Nashville, TN 37232-8548, United States ; Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232-8548, United States
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7
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Knippschild U, Krüger M, Richter J, Xu P, García-Reyes B, Peifer C, Halekotte J, Bakulev V, Bischof J. The CK1 Family: Contribution to Cellular Stress Response and Its Role in Carcinogenesis. Front Oncol 2014; 4:96. [PMID: 24904820 PMCID: PMC4032983 DOI: 10.3389/fonc.2014.00096] [Citation(s) in RCA: 188] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Accepted: 04/18/2014] [Indexed: 12/19/2022] Open
Abstract
Members of the highly conserved and ubiquitously expressed pleiotropic CK1 family play major regulatory roles in many cellular processes including DNA-processing and repair, proliferation, cytoskeleton dynamics, vesicular trafficking, apoptosis, and cell differentiation. As a consequence of cellular stress conditions, interaction of CK1 with the mitotic spindle is manifold increased pointing to regulatory functions at the mitotic checkpoint. Furthermore, CK1 is able to alter the activity of key proteins in signal transduction and signal integration molecules. In line with this notion, CK1 is tightly connected to the regulation and degradation of β-catenin, p53, and MDM2. Considering the importance of CK1 for accurate cell division and regulation of tumor suppressor functions, it is not surprising that mutations and alterations in the expression and/or activity of CK1 isoforms are often detected in various tumor entities including cancer of the kidney, choriocarcinomas, breast carcinomas, oral cancer, adenocarcinomas of the pancreas, and ovarian cancer. Therefore, scientific effort has enormously increased (i) to understand the regulation of CK1 and its involvement in tumorigenesis- and tumor progression-related signal transduction pathways and (ii) to develop CK1-specific inhibitors for the use in personalized therapy concepts. In this review, we summarize the current knowledge regarding CK1 regulation, function, and interaction with cellular proteins playing central roles in cellular stress-responses and carcinogenesis.
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Affiliation(s)
- Uwe Knippschild
- Department of General and Visceral Surgery, Surgery Center, Ulm University Hospital , Ulm , Germany
| | - Marc Krüger
- Department of General and Visceral Surgery, Surgery Center, Ulm University Hospital , Ulm , Germany
| | - Julia Richter
- Department of General and Visceral Surgery, Surgery Center, Ulm University Hospital , Ulm , Germany
| | - Pengfei Xu
- Department of General and Visceral Surgery, Surgery Center, Ulm University Hospital , Ulm , Germany
| | - Balbina García-Reyes
- Department of General and Visceral Surgery, Surgery Center, Ulm University Hospital , Ulm , Germany
| | - Christian Peifer
- Institute for Pharmaceutical Chemistry, Christian Albrechts University , Kiel , Germany
| | - Jakob Halekotte
- Institute for Pharmaceutical Chemistry, Christian Albrechts University , Kiel , Germany
| | - Vasiliy Bakulev
- Department of Organic Synthesis, Ural Federal University , Ekaterinburg , Russia
| | - Joachim Bischof
- Department of General and Visceral Surgery, Surgery Center, Ulm University Hospital , Ulm , Germany
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8
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Regulation of Golgi signaling and trafficking by the KDEL receptor. Histochem Cell Biol 2013; 140:395-405. [DOI: 10.1007/s00418-013-1130-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/09/2013] [Indexed: 12/31/2022]
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9
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CK1δ kinase activity is modulated by Chk1-mediated phosphorylation. PLoS One 2013; 8:e68803. [PMID: 23861943 PMCID: PMC3701638 DOI: 10.1371/journal.pone.0068803] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Accepted: 06/01/2013] [Indexed: 12/19/2022] Open
Abstract
CK1δ, a member of the casein kinase 1 family, is involved in the regulation of various cellular processes and has been associated with the pathophysiology of neurodegenerative diseases and cancer. Therefore recently, interest in generating highly specific inhibitors for personalized therapy has increased enormously. However, the efficacy of newly developed inhibitors is affected by the phosphorylation state of CK1δ. Cellular kinases phosphorylating CK1δ within its C-terminal domain have been identified but still more information regarding the role of site-specific phosphorylation in modulating the activity of CK1δ is required. Here we show that Chk1 phosphorylates rat CK1δ at serine residues 328, 331, 370, and threonine residue 397 as well as the human CK1δ transcription variants 1 and 2. CK1δ mutant proteins bearing one, two or three mutations at these identified phosphorylation sites exhibited significant differences in their kinetic properties compared to wild-type CK1δ. Additionally, CK1δ co-precipitates with Chk1 from HT1080 cell extracts and activation of cellular Chk1 resulted in a significant decrease in cellular CK1δ kinase activity. Taken together, these data point towards a possible regulatory relationship between Chk1 and CK1δ.
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Ishigami T, Abe K, Aoki I, Minegishi S, Ryo A, Matsunaga S, Matsuoka K, Takeda H, Sawasaki T, Umemura S, Endo Y. Anti‐interleukin‐5 and multiple autoantibodies are associated with human atherosclerotic diseases and serum interleukin‐5 levels. FASEB J 2013; 27:3437-45. [DOI: 10.1096/fj.12-222653] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Tomoaki Ishigami
- Department of Medical Science and Cardiorenal MedicineYokohama City University Graduate School of MedicineYokohamaJapan
| | - Kaito Abe
- Department of Medical Science and Cardiorenal MedicineYokohama City University Graduate School of MedicineYokohamaJapan
| | - Ichiro Aoki
- Department of Molecular PathologyYokohama City University Graduate School of MedicineYokohamaJapan
| | - Shintaro Minegishi
- Department of Medical Science and Cardiorenal MedicineYokohama City University Graduate School of MedicineYokohamaJapan
| | - Akihide Ryo
- Department of MicrobiologyYokohama City University Graduate School of MedicineYokohamaJapan
| | - Satoko Matsunaga
- Department of MicrobiologyYokohama City University Graduate School of MedicineYokohamaJapan
| | - Kazuhiro Matsuoka
- Ehime University Cell‐Free Science and Technology Research Center Division of Proteomedical Sciences; EhimeJapan
| | - Hiroyuki Takeda
- Ehime University Cell‐Free Science and Technology Research Center Division of Proteomedical Sciences; EhimeJapan
| | - Tatsuya Sawasaki
- Ehime University Cell‐Free Science and Technology Research Center Division of Proteomedical Sciences; EhimeJapan
| | - Satoshi Umemura
- Department of Medical Science and Cardiorenal MedicineYokohama City University Graduate School of MedicineYokohamaJapan
| | - Yaeta Endo
- Ehime University Cell‐Free Science and Technology Research Center Division of Proteomedical Sciences; EhimeJapan
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11
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Cancino J, Luini A. Signaling Circuits on the Golgi Complex. Traffic 2012; 14:121-34. [DOI: 10.1111/tra.12022] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Revised: 10/12/2012] [Accepted: 10/12/2012] [Indexed: 01/21/2023]
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12
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Gao J, Takeuchi H, Zhang Z, Fukuda M, Hirata M. Phospholipase C-related but catalytically inactive protein (PRIP) modulates synaptosomal-associated protein 25 (SNAP-25) phosphorylation and exocytosis. J Biol Chem 2012; 287:10565-10578. [PMID: 22311984 DOI: 10.1074/jbc.m111.294645] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Exocytosis is one of the most fundamental cellular events. The basic mechanism of the final step, membrane fusion, is mediated by the formation of the SNARE complex, which is modulated by the phosphorylation of proteins controlled by the concerted actions of protein kinases and phosphatases. We have previously shown that a protein phosphatase-1 (PP1) anchoring protein, phospholipase C-related but catalytically inactive protein (PRIP), has an inhibitory role in regulated exocytosis. The current study investigated the involvement of PRIP in the phospho-dependent modulation of exocytosis. Dephosphorylation of synaptosome-associated protein of 25 kDa (SNAP-25) was mainly catalyzed by PP1, and the process was modulated by wild-type PRIP but not by the mutant (F97A) lacking PP1 binding ability in in vitro studies. We then examined the role of PRIP in phospho-dependent regulation of exocytosis in cell-based studies using pheochromocytoma cell line PC12 cells, which secrete noradrenalin. Exogenous expression of PRIP accelerated the dephosphorylation process of phosphorylated SNAP-25 after forskolin or phorbol ester treatment of the cells. The phospho-states of SNAP-25 were correlated with noradrenalin secretion, which was enhanced by forskolin or phorbol ester treatment and modulated by PRIP expression in PC12 cells. Both SNAP-25 and PP1 were co-precipitated in anti-PRIP immunocomplex isolated from PC12 cells expressing PRIP. Collectively, together with our previous observation regarding the roles of PRIP in PP1 regulation, these results suggest that PRIP is involved in the regulation of the phospho-states of SNAP-25 by modulating the activity of PP1, thus regulating exocytosis.
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Affiliation(s)
- Jing Gao
- Laboratory of Molecular and Cellular Biochemistry, Faculty of Dental Science, Kyushu University, Fukuoka 812-8582, Japan and
| | - Hiroshi Takeuchi
- Laboratory of Molecular and Cellular Biochemistry, Faculty of Dental Science, Kyushu University, Fukuoka 812-8582, Japan and
| | - Zhao Zhang
- Laboratory of Molecular and Cellular Biochemistry, Faculty of Dental Science, Kyushu University, Fukuoka 812-8582, Japan and
| | - Mitsunori Fukuda
- Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Masato Hirata
- Laboratory of Molecular and Cellular Biochemistry, Faculty of Dental Science, Kyushu University, Fukuoka 812-8582, Japan and.
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Gil C, Falqués A, Sarró E, Cubi R, Blasi J, Aguilera J, Itarte E. Protein kinase CK2 associates to lipid rafts and its pharmacological inhibition enhances neurotransmitter release. FEBS Lett 2010; 585:414-20. [PMID: 21187092 DOI: 10.1016/j.febslet.2010.12.029] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Revised: 12/17/2010] [Accepted: 12/17/2010] [Indexed: 01/14/2023]
Abstract
In the present work we report the presence of protein kinase CK2 in lipid raft preparations from rat brain synaptosomes, obtained after detergent extraction and subsequent isolation of detergent-resistant membranes using sucrose gradient ultracentrifugation. Moreover, the phosphorylation of syntaxin-1 at Ser14, a specific CK2 target, has been detected in lipid rafts, as assessed by a phospho-specific antibody. Treatment with DMAT, a specific CK2 inhibitor, results in a decrease of syntaxin-1 Ser14 phosphorylation in lipid rafts, while the glutamate release from synaptosomes is enhanced. In conclusion, CK2 might control neurotransmitter release by acting on SNARE proteins attached to cholesterol-enriched microdomains.
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Affiliation(s)
- Carles Gil
- Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Barcelona, Spain.
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14
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Trost M, Bridon G, Desjardins M, Thibault P. Subcellular phosphoproteomics. MASS SPECTROMETRY REVIEWS 2010; 29:962-90. [PMID: 20931658 DOI: 10.1002/mas.20297] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Protein phosphorylation represents one of the most extensively studied post-translational modifications, primarily due to the emergence of sensitive methods enabling the detection of this modification both in vitro and in vivo. The availability of enrichment methods combined with sensitive mass spectrometry instrumentation has played a crucial role in uncovering the dynamic changes and the large expanding repertoire of this reversible modification. The structural changes imparted by the phosphorylation of specific residues afford exquisite mechanisms for the regulation of protein functions by modulating new binding sites on scaffold proteins or by abrogating protein-protein interactions. However, the dynamic interplay of protein phosphorylation is not occurring randomly within the cell but is rather finely orchestrated by specific kinases and phosphatases that are unevenly distributed across subcellular compartments. This spatial separation not only regulates protein phosphorylation but can also control the activity of other enzymes and the transfer of other post-translational modifications. While numerous large-scale phosphoproteomics studies highlighted the extent and diversity of phosphoproteins present in total cell lysates, the further understanding of their regulation and biological activities require a spatio-temporal resolution only achievable through subcellular fractionation. This review presents a first account of the emerging field of subcellular phosphoproteomics where cell fractionation approaches are combined with sensitive mass spectrometry methods to facilitate the identification of low abundance proteins and to unravel the intricate regulation of protein phosphorylation.
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Affiliation(s)
- Matthias Trost
- Institute for Research in Immunology and Cancer, Université de Montréal, P.O. Box 6128, Station Centre-ville, Montréal, Québec, Canada H3C 3J7
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15
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Utz AC, Hirner H, Blatz A, Hillenbrand A, Schmidt B, Deppert W, Henne-Bruns D, Fischer D, Thal DR, Leithäuser F, Knippschild U. Analysis of cell type-specific expression of CK1 epsilon in various tissues of young adult BALB/c Mice and in mammary tumors of SV40 T-Ag-transgenic mice. J Histochem Cytochem 2009; 58:1-15. [PMID: 19755715 DOI: 10.1369/jhc.2009.954628] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Casein kinase 1 epsilon (CK1epsilon) is involved in various cellular processes, including cell growth, differentiation, and apoptosis, vesicle transport, and control of the circadian rhythm. Deregulation of CK1epsilon has been linked to neurodegenerative diseases and cancer. To better understand the cell type-specific functions of CK1epsilon, we determined its localization by immunhistochemistry in tissues of healthy, young adult BALB/c mice and in mammary tumors of SV40 T-antigen-transgenic mice. CK1epsilon expression was found to be highly regulated in normal tissues of endodermal, mesodermal, and ectodermal origin and in neoplastic tissue of mammary cancer. The data presented here give an overview of CK1epsilon reactivity in different organs under normal conditions and outline changes in its expression in mammary carcinomas. Our data suggest a cell/organ type-specific function of CK1epsilon and indicate that tumorigenic conversion of mammary glands in SV40 T-antigen-transgenic mice leads to downregulation of CK1epsilon. This manuscript contains online supplemental material at http://www.jhc.org. Please visit this article online to view these materials.
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Affiliation(s)
- Anja C Utz
- Department of General, Visceral, and Transplantation Surgery, University of Ulm, Steinhövelstr. 9, 89075 Ulm, Germany
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16
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Löhler J, Hirner H, Schmidt B, Kramer K, Fischer D, Thal DR, Leithäuser F, Knippschild U. Immunohistochemical characterisation of cell-type specific expression of CK1delta in various tissues of young adult BALB/c mice. PLoS One 2009; 4:e4174. [PMID: 19137063 PMCID: PMC2613528 DOI: 10.1371/journal.pone.0004174] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2008] [Accepted: 11/24/2008] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Casein kinase 1 delta (CK1delta) phosphorylates many key proteins playing important roles in such biological processes as cell growth, differentiation, apoptosis, circadian rhythm and vesicle transport. Furthermore, deregulation of CK1delta has been linked to neurodegenerative diseases and cancer. In this study, the cell specific distribution of CK1delta in various tissues and organs of young adult BALB/c mice was analysed by immunohistochemistry. METHODOLOGY/PRINCIPAL FINDINGS Immunohistochemical staining of CK1delta was performed using three different antibodies against CK1delta. A high expression of CK1delta was found in a variety of tissues and organ systems and in several cell types of endodermal, mesodermal and ectodermal origin. CONCLUSIONS These results give an overview of the cell-type specific expression of CK1delta in different organs under normal conditions. Thus, they provide evidence for possible cell-type specific functions of CK1delta, where CK1delta can interact with and modulate the activity of key regulator proteins by site directed phosphorylation. Furthermore, they provide the basis for future analyses of CK1delta in these tissues.
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Affiliation(s)
- Jürgen Löhler
- Molecular Pathology Group, Heinrich-Pette-Institute for Experimental Immunology and Virology, University Hamburg, Hamburg, Germany
| | - Heidrun Hirner
- Department of General-, Visceral- and Transplantation Surgery, University of Ulm, Ulm, Germany
| | - Bernhard Schmidt
- Department of General-, Visceral- and Transplantation Surgery, University of Ulm, Ulm, Germany
| | - Klaus Kramer
- Department of General-, Visceral- and Transplantation Surgery, University of Ulm, Ulm, Germany
| | - Dietmar Fischer
- Department of Experimental Neurology, University of Ulm, Ulm, Germany
| | - Dietmar R. Thal
- Laboratory of Neuropathology, Institute of Pathology, University of Ulm, Ulm, Germany
| | | | - Uwe Knippschild
- Department of General-, Visceral- and Transplantation Surgery, University of Ulm, Ulm, Germany
- * E-mail:
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17
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Pajonk S, Kwon C, Clemens N, Panstruga R, Schulze-Lefert P. Activity determinants and functional specialization of Arabidopsis PEN1 syntaxin in innate immunity. J Biol Chem 2008; 283:26974-84. [PMID: 18678865 DOI: 10.1074/jbc.m805236200] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
In eukaryotes, proteins of the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) family are believed to have a general role for the fusion of intracellular transport vesicles with acceptor membranes. Arabidopsis thaliana PEN1 syntaxin resides in the plasma membrane and was previously shown to act together with its partner SNAREs, the adaptor protein SNAP33, and endomembrane-anchored VAMP721/722 in the execution of secretory immune responses against powdery mildew fungi. We conducted a structure-function analysis of PEN1 and show that N-terminal phospho-mimicking and non-phosphorylatable variants neither affected binary nor ternary SNARE complex formation with cognate partners in vitro. However, expression of these syntaxin variants at native protein levels in a pen1 mutant background suggests that phosphorylation is required for full resistance activity in planta. All tested site-directed substitutions of SNARE domain or "linker region" residues reduced PEN1 defense activity. Two of the variants failed to form ternary complexes with the partner SNAREs in vitro, possibly explaining their diminished in planta activity. However, impaired pathogen defense in plants expressing a linker region variant is likely because of PEN1 destabilization. Although Arabidopsis PEN1 and SYP122 syntaxins share overlapping functions in plant growth and development, PEN1 activity in disease resistance is apparently the result of a complete functional specialization. Our findings are consistent with the hypothesis that PEN1 acts in plant defense through the formation of ternary SNARE complexes and point to the existence of unknown regulatory factors. Our data indirectly support structural inferences that the four-helical coiled coil bundle in ternary SNARE complexes is formed in a sequential order from the N- to C-terminal direction.
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Affiliation(s)
- Simone Pajonk
- Max Planck Institute for Plant Breeding Research, Department of Plant Microbe Interactions, D-50829 Köln, Germany
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18
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Phosphorylation of RhoB by CK1 impedes actin stress fiber organization and epidermal growth factor receptor stabilization. Exp Cell Res 2008; 314:2811-21. [PMID: 18590726 DOI: 10.1016/j.yexcr.2008.06.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2008] [Revised: 06/10/2008] [Accepted: 06/11/2008] [Indexed: 11/21/2022]
Abstract
RhoB is a small GTPase implicated in cytoskeletal organization, EGF receptor trafficking and cell transformation. It is an immediate-early gene, regulated at many levels of its biosynthetic pathway. Herein we show that the serine/threonine protein kinase CK1 phosphorylates RhoB in vitro but not RhoA or RhoC. With the use of specific CK1 inhibitors, IC261 and D4476, we show that the kinase phosphorylates also RhoB in HeLa cells. Mass spectrometry analysis demonstrates that RhoB is monophosphorylated by CK1, in its C-terminal end, on serine 185. The substitution of Ser185 by Ala dramatically inhibited the phosphorylation of RhoB in cultured cells. Lastly we show that the inhibition of CK1 activates RhoB and promotes RhoB dependent actin fiber formation and EGF-R level. Our data provide the first demonstration of RhoB phosphorylation and indicate that this post-translational maturation would be a novel critical mechanism to control the RhoB functions.
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19
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Oh E, Thurmond DC. The stimulus-induced tyrosine phosphorylation of Munc18c facilitates vesicle exocytosis. J Biol Chem 2006; 281:17624-34. [PMID: 16638745 PMCID: PMC2396333 DOI: 10.1074/jbc.m601581200] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Stimulus-induced tyrosine phosphorylation of Munc18c was investigated as a potential regulatory mechanism by which the Munc18c-Syntaxin 4 complex can be dissociated in response to divergent stimuli in multiple cell types. Use of [(32)P]orthophosphate incorporation, pervanadate treatment, and phosphotyrosine-specific antibodies demonstrated that Munc18c underwent tyrosine phosphorylation. Phosphorylation was apparent under basal conditions, but levels were significantly increased within 5 min of glucose stimulation in MIN6 beta cells. Tyrosine phosphorylation of Munc18c was also detected in 3T3L1 adipocytes and increased with insulin stimulation, suggesting that this may be a conserved mechanism. Syntaxin 4 binding to Munc18c decreased as Munc18c phosphorylation levels increased in pervanadate-treated cells, suggesting that phosphorylation dissociates the Munc18c-Syntaxin 4 complex. Munc18c phosphorylation was localized to the N-terminal 255 residues. Mutagenesis of one residue in this region, Y219F, significantly increased the affinity of Munc18c for Syntaxin 4, whereas mutation of three other candidate sites was without effect. Moreover, Munc18c-Y219F expression in MIN6 cells functionally inhibited glucose-stimulated SNARE complex formation and insulin granule exocytosis. These data support a novel and conserved mechanism for the dissociation of Munc18c-Syntaxin 4 complexes in a stimulus-dependent manner to facilitate the increase in Syntaxin 4-VAMP2 association and to promote vesicle/granule fusion.
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Affiliation(s)
| | - Debbie C. Thurmond
- To whom correspondence should be addressed: Dept. of Biochemistry and Molecular Biology, Center for Diabetes Research, Indiana University School of Medicine, 635 Barnhill Dr., MS 4053, Indianapolis, IN 46202. Tel.: 317−274−1551; Fax: 317−274−4686; E-mail:
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20
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DeGiorgis JA, Jaffe H, Moreira JE, Carlotti CG, Leite JP, Pant HC, Dosemeci A. Phosphoproteomic analysis of synaptosomes from human cerebral cortex. J Proteome Res 2005; 4:306-15. [PMID: 15822905 DOI: 10.1021/pr0498436] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Protein phosphorylation is a crucial post-translational modification mechanism in the regulation of synaptic organization and function. Here, we analyzed synaptosome fractions from human cerebral cortex obtained during therapeutic surgery. To minimize changes in the phosphorylation state of proteins, the tissue was homogenized within two minutes of excision. Synaptosomal proteins were digested with trypsin and phosphopeptides were isolated by immobilized metal affinity chromatography and analyzed by liquid chromatography and tandem mass spectrometry. The method allowed the detection of residues on synaptic proteins that were presumably phosphorylated in the intact cell, including synapsin 1, syntaxin 1, and SNIP, PSD-93, NCAM, GABA-B receptor, chaperone molecules, and protein kinases. Some of the residues identified are the same or homologous to sites that had been previously described to be phosphorylated in mammals whereas others appear to be novel sites which, to our knowledge, have not been reported previously. The study shows that new phosphoproteomic strategies can be used to analyze subcellular fractions from small amounts of tissue for the identification of phosphorylated residues for research and potentially for diagnostic purposes.
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Affiliation(s)
- Joseph A DeGiorgis
- Laboratory of Neurobiology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA
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21
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Knippschild U, Gocht A, Wolff S, Huber N, Löhler J, Stöter M. The casein kinase 1 family: participation in multiple cellular processes in eukaryotes. Cell Signal 2005; 17:675-89. [PMID: 15722192 DOI: 10.1016/j.cellsig.2004.12.011] [Citation(s) in RCA: 420] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2004] [Revised: 12/22/2004] [Accepted: 12/22/2004] [Indexed: 12/11/2022]
Abstract
Phosphorylation of serine, threonine and tyrosine residues by cellular protein kinases plays an important role in the regulation of various cellular processes. The serine/threonine specific casein kinase 1 and 2 protein kinase families--(CK1 and CK2)--were among the first protein kinases that had been described. In recent years our knowledge of the regulation and function of mammalian CK1 kinase family members has rapidly increased. Extracellular stimuli, the subcellular localization of CK1 isoforms, their interaction with various cellular structures and proteins, as well as autophosphorylation and proteolytic cleavage of their C-terminal regulatory domains influence CK1 kinase activity. Mammalian CK1 isoforms phosphorylate many different substrates among them key regulatory proteins involved in the control of cell differentiation, proliferation, chromosome segregation and circadian rhythms. Deregulation and/or the incidence of mutations in the coding sequence of CK1 isoforms have been linked to neurodegenerative diseases and cancer. This review will summarize our current knowledge about the function and regulation of mammalian CK1 isoforms.
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Affiliation(s)
- Uwe Knippschild
- Department of Visceral and Transplantation Surgery, University of Ulm, Steinhövelstr. 9, 89075 Ulm, Germany.
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22
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Nühse TS, Boller T, Peck SC. A plasma membrane syntaxin is phosphorylated in response to the bacterial elicitor flagellin. J Biol Chem 2003; 278:45248-54. [PMID: 12949074 DOI: 10.1074/jbc.m307443200] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In vivo pulse labeling of suspension-cultured Arabidopsis cells with [32P]orthophosphate allows a systematic analysis of dynamic changes in protein phosphorylation. Here, we use this technique to investigate signal transduction events at the plant plasma membrane triggered upon perception of microbial elicitors of defense responses, using as a model elicitor flg22, a peptide corresponding to the most conserved domain of bacterial flagellin. We demonstrate that two-dimensional gel electrophoresis in conjunction with mass spectrometry is a suitable tool for the identification of intrinsic membrane proteins, and we show that among them a syntaxin, AtSyp122, is phosphorylated rapidly in response to flg22. Although incorporation of radioactive phosphate into the protein only occurs significantly after elicitation, immunoblot analysis after two-dimensional gel separation indicates that the protein is also phosphorylated prior to elicitation. These results indicate that flg22 elicits either an increase in the rate of turnover of phosphate or an additional de novo phosphorylation event. In vitro, phosphorylation of AtSyp122 is calcium-dependent. In vitro phosphorylated peptides separated by two-dimensional thin layer chromatography comigrate with two of the three in vivo phosphopeptides, indicating that this calcium-dependent phosphorylation is biologically relevant. These results indicate a regulatory link between elicitor-induced calcium fluxes and the rapid phosphorylation of a syntaxin. Because syntaxins are known to be important in membrane fusion and exocytosis, we hypothesize that one of the functions of the calcium signal is to stimulate exocytosis of defense-related proteins and compounds.
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Affiliation(s)
- Thomas S Nühse
- Friedrich-Miescher Institute of Biomedical Research, 4002 Basel, Switzerland
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23
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Zemlickova E, Dubois T, Kerai P, Clokie S, Cronshaw AD, Wakefield RID, Johannes FJ, Aitken A. Centaurin-alpha(1) associates with and is phosphorylated by isoforms of protein kinase C. Biochem Biophys Res Commun 2003; 307:459-65. [PMID: 12893243 DOI: 10.1016/s0006-291x(03)01187-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Centaurin-alpha(1) is a member of the family of ADP-ribosylation factors (ARF) GTPase activating proteins (GAPs), although ARF GAP activity has not yet been demonstrated. The human homologue, centaurin-alpha(1) functionally complements the ARF GAP activity of Gcs1 in yeast. Although Gcs1 is involved in the formation of actin filaments in vivo, the function of centaurin remains elusive. We have identified a number of novel centaurin-alpha(1) binding partners; including CKIalpha and nucleolin. In this report, we have focused on the interaction of centaurin-alpha(1) with PKC. All groups of PKC associate directly through their cysteine rich domains. Centaurin-alpha(1) is also a substrate for all PKC classes and we have identified the two sites of phosphorylation. This is the first report of a kinase that phosphorylates centaurin-alpha(1).
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Affiliation(s)
- Eva Zemlickova
- University of Edinburgh, School of Biomedical and Clinical Laboratory Sciences, Hugh Robson Building, George Square, Edinburgh EH8 9XD, UK
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24
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Tian JH, Das S, Sheng ZH. Ca2+-dependent phosphorylation of syntaxin-1A by the death-associated protein (DAP) kinase regulates its interaction with Munc18. J Biol Chem 2003; 278:26265-74. [PMID: 12730201 DOI: 10.1074/jbc.m300492200] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Syntaxin-1 is a key component of the synaptic vesicle docking/fusion machinery that binds with VAMP/synaptobrevin and SNAP-25 to form the SNARE complex. Modulation of syntaxin binding properties by protein kinases could be critical to control of neurotransmitter release. Using yeast two-hybrid selection with syntaxin-1A as bait, we have isolated a cDNA encoding the C-terminal domain of death-associated protein (DAP) kinase, a calcium/calmodulin-dependent serine/threonine protein kinase. Expression of DAP kinase in adult rat brain is restricted to particular neuronal subpopulations, including the hippocampus and cerebral cortex. Biochemical studies demonstrate that DAP kinase binds to and phosphorylates syntaxin-1 at serine 188. This phosphorylation event occurs both in vitro and in vivo in a Ca2+-dependent manner. Syntaxin-1A phosphorylation by DAP kinase or its S188D mutant, which mimics a state of complete phosphorylation, significantly decreases syntaxin binding to Munc18-1, a syntaxin-binding protein that regulates SNARE complex formation and is required for synaptic vesicle docking. Our results suggest that syntaxin is a DAP kinase substrate and provide a novel signal transduction pathway by which syntaxin function could be regulated in response to intracellular [Ca2+] and synaptic activity.
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Affiliation(s)
- Jin-Hua Tian
- Synaptic Function Unit, NINDS, National Institutes of Health, Bethesda, Maryland 20892-4154, USA
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25
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Abstract
CK2 (formerly termed "casein kinase 2") is a ubiquitous, highly pleiotropic and constitutively active Ser/Thr protein kinase whose implication in neoplasia, cell survival, and virus infection is supported by an increasing number of arguments. Here an updated inventory of 307 CK2 protein substrates is presented. More than one-third of these are implicated in gene expression and protein synthesis as being either transcriptional factors (60) or effectors of DNA/RNA structure (50) or translational elements. Also numerous are signaling proteins and proteins of viral origin or essential to virus life cycle. In comparison, only a minority of CK2 targets (a dozen or so) are classical metabolic enzymes. An analysis of 308 sites phosphorylated by CK2 highlights the paramount relevance of negatively charged side chains that are (by far) predominant over any other residues at positions n+3 (the most crucial one), n+1, and n+2. Based on this signature, it is predictable that proteins phosphorylated by CK2 are much more numerous than those identified to date, and it is possible that CK2 alone contributes to the generation of the eukaryotic phosphoproteome more so than any other individual protein kinase. The possibility that CK2 phosphosites play some global role, e.g., by destabilizing alpha helices, counteracting caspase cleavage, and generating adhesive motifs, will be discussed.
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Affiliation(s)
- Flavio Meggio
- Dipartimento di Chimica Biologica and Istituto di Neuroscienze del CNR, Università di Padova and Venetian Institute for Molecular Medicine (VIMM), Padova, Italy
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