1
|
Tavares CDJ, Giles DH, Stancu G, Chitjian CA, Ferguson SB, Wellmann RM, Kaoud TS, Ghose R, Dalby KN. Signal Integration at Elongation Factor 2 Kinase: THE ROLES OF CALCIUM, CALMODULIN, AND SER-500 PHOSPHORYLATION. J Biol Chem 2016; 292:2032-2045. [PMID: 27956550 DOI: 10.1074/jbc.m116.753277] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 11/28/2016] [Indexed: 12/22/2022] Open
Abstract
Eukaryotic elongation factor 2 kinase (eEF-2K), the only calmodulin (CaM)-dependent member of the unique α-kinase family, impedes protein synthesis by phosphorylating eEF-2. We recently identified Thr-348 and Ser-500 as two key autophosphorylation sites within eEF-2K that regulate its activity. eEF-2K is regulated by Ca2+ ions and multiple upstream signaling pathways, but how it integrates these signals into a coherent output, i.e. phosphorylation of eEF-2, is unclear. This study focuses on understanding how the post-translational phosphorylation of Ser-500 integrates with Ca2+ and CaM to regulate eEF-2K. CaM is shown to be absolutely necessary for efficient activity of eEF-2K, and Ca2+ is shown to enhance the affinity of CaM toward eEF-2K. Ser-500 is found to undergo autophosphorylation in cells treated with ionomycin and is likely also targeted by PKA. In vitro, autophosphorylation of Ser-500 is found to require Ca2+ and CaM and is inhibited by mutations that compromise binding of phosphorylated Thr-348 to an allosteric binding pocket on the kinase domain. A phosphomimetic Ser-500 to aspartic acid mutation (eEF-2K S500D) enhances the rate of activation (Thr-348 autophosphorylation) by 6-fold and lowers the EC50 for Ca2+/CaM binding to activated eEF-2K (Thr-348 phosphorylated) by 20-fold. This is predicted to result in an elevation of the cellular fraction of active eEF-2K. In support of this mechanism, eEF-2K knock-out MCF10A cells reconstituted with eEF-2K S500D display relatively high levels of phospho-eEF-2 under basal conditions. This study reports how phosphorylation of a regulatory site (Ser-500) integrates with Ca2+ and CaM to influence eEF-2K activity.
Collapse
Affiliation(s)
- Clint D J Tavares
- From the Graduate Program in Cell and Molecular Biology, University of Texas, Austin, Texas 78712; Division of Chemical Biology and Medicinal Chemistry, University of Texas, Austin, Texas 78712.
| | - David H Giles
- Division of Chemical Biology and Medicinal Chemistry, University of Texas, Austin, Texas 78712
| | - Gabriel Stancu
- Division of Chemical Biology and Medicinal Chemistry, University of Texas, Austin, Texas 78712
| | - Catrina A Chitjian
- From the Graduate Program in Cell and Molecular Biology, University of Texas, Austin, Texas 78712; Division of Chemical Biology and Medicinal Chemistry, University of Texas, Austin, Texas 78712
| | - Scarlett B Ferguson
- Division of Chemical Biology and Medicinal Chemistry, University of Texas, Austin, Texas 78712
| | - Rebecca M Wellmann
- Division of Chemical Biology and Medicinal Chemistry, University of Texas, Austin, Texas 78712
| | - Tamer S Kaoud
- Division of Chemical Biology and Medicinal Chemistry, University of Texas, Austin, Texas 78712
| | - Ranajeet Ghose
- the Department of Chemistry, City College of New York, New York, New York 10031; the Graduate Center, City University of New York, New York, New York 10016
| | - Kevin N Dalby
- From the Graduate Program in Cell and Molecular Biology, University of Texas, Austin, Texas 78712; Division of Chemical Biology and Medicinal Chemistry, University of Texas, Austin, Texas 78712.
| |
Collapse
|
2
|
Wiseman SL, Shimizu Y, Palfrey C, Nairn AC. Proteasomal degradation of eukaryotic elongation factor-2 kinase (EF2K) is regulated by cAMP-PKA signaling and the SCFβTRCP ubiquitin E3 ligase. J Biol Chem 2013; 288:17803-11. [PMID: 23640883 DOI: 10.1074/jbc.m113.477182] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Protein translation and degradation are critical for proper protein homeostasis, yet it remains unclear how these processes are dynamically regulated, or how they may directly balance or synergize with each other. An important translational control mechanism is the Ca(2+)/calmodulin-dependent phosphorylation of eukaryotic elongation factor-2 (eEF-2) by eukaryotic elongation factor-2 kinase (EF2K), which inhibits elongation of nascent polypeptide chains during translation. We previously described a reduction of EF2K activity in PC12 cells treated with NGF or forskolin. Here, we show that both forskolin- and IGF-1-mediated reductions of EF2K activity in PC12 cells are due to decreased EF2K protein levels, and this is attenuated by application of the proteasome inhibitor, MG132. We further demonstrate that proteasome-mediated degradation of EF2K occurs in response to A2A-type adenosine receptor stimulation, and that activation of protein kinase A (PKA) or phospho-mimetic mutation of the previously characterized PKA site, Ser-499, were sufficient to induce EF2K turnover in PC12 cells. A similar EF2K degradation mechanism was observed in primary neurons and HEK cells. Expression of a dominant-negative form of Cul1 in HEK cells demonstrated that EF2K levels are regulated by an SCF-type ubiquitin E3 ligase. Specifically, EF2K binds to the F-box proteins, βTRCP1 and βTRCP2, and βTRCP regulates EF2K levels and polyubiquitylation. We propose that the proteasomal degradation of EF2K provides a mechanistic link between activity-dependent protein synthesis and degradation.
Collapse
Affiliation(s)
- Shari L Wiseman
- Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut 06508, USA
| | | | | | | |
Collapse
|
3
|
Chen L, Lau AG, Sarti F. Synaptic retinoic acid signaling and homeostatic synaptic plasticity. Neuropharmacology 2012; 78:3-12. [PMID: 23270606 DOI: 10.1016/j.neuropharm.2012.12.004] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Revised: 12/08/2012] [Accepted: 12/14/2012] [Indexed: 01/03/2023]
Abstract
One of the defining features of the nervous system is its ability to modify synaptic strength in an experience-dependent manner. Chronic elevation or reduction of network activity activates compensatory mechanisms that modulate synaptic strength in the opposite direction (i.e. reduced network activity leads to increased synaptic strength), a process called homeostatic synaptic plasticity. Among the many mechanisms that mediate homeostatic synaptic plasticity, retinoic acid (RA) has emerged as a novel signaling molecule that is critically involved in homeostatic synaptic plasticity induced by blockade of synaptic activity. In neurons, silencing of synaptic transmission triggers RA synthesis. RA then acts at synapses by a non-genomic mechanism that is independent of its well-known function as a transcriptional regulator, but operates through direct activation of protein translation in neuronal dendrites. Protein synthesis is activated by RA-binding to its receptor RARα, which functions locally in dendrites in a non-canonical manner as an RNA-binding protein that mediate RA's effect on translation. The present review will discuss recent progress in our understanding of the novel role of RA, which led to the identification of RA as a critical synaptic signaling molecule that mediates activity-dependent regulation of protein synthesis in neuronal dendrites. This article is part of the Special Issue entitled 'Homeostatic Synaptic Plasticity'.
Collapse
Affiliation(s)
- Lu Chen
- Stanford Institute of Neuro-Innovation and Translational Neuroscience, and Department of Psychiatry and Behavioral Sciences, Stanford University, School of Medicine, Stanford, CA 94305-5453, USA.
| | - Anthony G Lau
- Stanford Institute of Neuro-Innovation and Translational Neuroscience, and Department of Psychiatry and Behavioral Sciences, Stanford University, School of Medicine, Stanford, CA 94305-5453, USA
| | - Federica Sarti
- Stanford Institute of Neuro-Innovation and Translational Neuroscience, and Department of Psychiatry and Behavioral Sciences, Stanford University, School of Medicine, Stanford, CA 94305-5453, USA; University of California, Department of Molecular and Cell Biology, Berkeley, CA 94720-3200, USA
| |
Collapse
|
4
|
Nairn AC, Matsushita M, Nastiuk K, Horiuchi A, Mitsui K, Shimizu Y, Palfrey HC. Elongation factor-2 phosphorylation and the regulation of protein synthesis by calcium. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2002; 27:91-129. [PMID: 11575162 DOI: 10.1007/978-3-662-09889-9_4] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Affiliation(s)
- A C Nairn
- Laboratory of Molecular and Cellular Neuroscience, Rockefeller University, New York, New York 10021, USA
| | | | | | | | | | | | | |
Collapse
|
5
|
Yang CM, Chiu CT, Wang CC, Tsao HL, Fan LW. Forskolin inhibits 5-hydroxytryptamine-induced phosphoinositide hydrolysis and Ca+2 Mobilisation in canine cultured aorta smooth muscle cells. Cell Signal 1999; 11:697-704. [PMID: 10530879 DOI: 10.1016/s0898-6568(99)00042-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The effect of forskolin on 5-hydroxytryptamine (5-HT)-induced inositol phosphate (IP) and Ca2+ mobilisation was investigated in canine cultured aorta smooth muscle cells (ASMCs). Pretreatment of ASMCs with forskolin attenuated 5-HT-induced IP accumulation and Ca2+ mobilisation in a time- and concentration-dependent manner. The half-maximal effects (pEC50) of forskolin to attenuate IP and Ca2+ responses to 5-HT occurred at concentrations of 6.28 and 6.64, respectively. Pretreatment of ASMCs with cholera toxin caused a similar inhibition on 5-HT-induced responses. Even after treatment with forskolin for 24 h, the 5-HT-induced responses were still inhibited. The inhibitory effect of forskolin resulted from both a depression of the maximal response and a shift to the right of the concentration-effect curves of 5-HT in these responses. The water-soluble forskolin analogue L-858051 [7-deacetyl-7beta-(gamma-N-methylpiperazino)-butyryl forskolin] significantly inhibited the 5-HT-stimulated IP accumulation. In contrast, the addition of 1,9-dideoxy forskolin, an inactive forskolin analogue, had little effect on IP response. Moreover, SQ-22536 [9-(tetrahydro-2-furanyl)-9-H-purin-6-amine], an inhibitor of adenylate cyclase, and both H-89 [N-(2-aminoethyl)-5-iosquinolinesulphonamide] and HA-1004 [N-(2-guanidinoethyl)-5-iosquinolinesulphonamide], inhibitors of cAMP-dependent protein kinase (PKA), attenuated the ability of forskolin to inhibit the 5-HT-stimulated accumulation of IP in ASMCs. These results indicate that activation of cAMP/PKA might inhibit the 5-HT-stimulated IP accumulation and consequently reduce Ca2+ mobilisation, or inhibit both responses independently.
Collapse
Affiliation(s)
- C M Yang
- Department of Pharmacology, College of Medicine, Chang Gung University, Kwei-San, Tao-Yuan, Taiwan.
| | | | | | | | | |
Collapse
|
6
|
Mendoza A, Serramía MJ, Capa L, García-Bustos JF. Translation elongation factor 2 is encoded by a single essential gene in Candida albicans. Gene 1999; 229:183-91. [PMID: 10095118 DOI: 10.1016/s0378-1119(99)00024-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Translation elongation factor 2 (eEF2) is a large protein of more than 800 amino acids which establishes complex interactions with the ribosome in order to catalyze the conformational changes needed for translation elongation. Unlike other yeasts, the pathogenic fungus Candida albicans was found to have a single gene encoding this factor per haploid genome, located on chromosome 2. Expression of this locus is essential for vegetative growth, as evidenced by placing it under the control of a repressible promoter. This C. albicans gene, named EFT2, was cloned and sequenced (EMBL accession number Y09664). Genomic and cDNA sequence analysis identified common transcription initiation and termination signals and an 842 amino acid open reading frame (ORF), which is interrupted by a single intron. Despite some genetic differences, CaEFT2 was capable of complementing a Saccharomyces cerevisiae Deltaeft1 Deltaeft2 null mutant, which lacks endogenous eEF2, indicating that CaEFT2 can be expressed from its own promoter and its intron can be correctly spliced in S. cerevisiae.
Collapse
Affiliation(s)
- A Mendoza
- Research Department, Glaxo Wellcome, S.A., Severo Ochoa 2, E-28760, Tres Cantos, Spain
| | | | | | | |
Collapse
|
7
|
Hovland R, Eikhom TS, Proud CG, Cressey LI, Lanotte M, Døskeland SO, Houge G. cAMP inhibits translation by inducing Ca2+/calmodulin-independent elongation factor 2 kinase activity in IPC-81 cells. FEBS Lett 1999; 444:97-101. [PMID: 10037155 DOI: 10.1016/s0014-5793(99)00039-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Treatment of IPC-81 cells led to inhibition of protein synthesis, which was accompanied by an increase in the average size of polysomes and a decreased rate of elongation, indicating that it involved inhibition of peptide chain elongation. This inhibition was also associated with increased phosphorylation of elongation factor eEF2 (which inhibits its activity) and enhanced Ca2+/calmodulin-independent activity of eEF2 kinase. Previous work has shown that phosphorylation of eEF2 kinase by cAMP-dependent protein kinase (cAPK) in vitro induces such activator-independent activity, and the present data show that such a mechanism can occur in intact cells to link physiological levels of cAPK activation with inhibition of protein synthesis.
Collapse
Affiliation(s)
- R Hovland
- Department of Anatomy and Cell Biology, University of Bergen, Norway
| | | | | | | | | | | | | |
Collapse
|
8
|
Brostrom CO, Brostrom MA. Regulation of translational initiation during cellular responses to stress. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 1997; 58:79-125. [PMID: 9308364 DOI: 10.1016/s0079-6603(08)60034-3] [Citation(s) in RCA: 207] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Chemicals and conditions that damage proteins, promote protein misfolding, or inhibit protein processing trigger the onset of protective homeostatic mechanisms resulting in "stress responses" in mammalian cells. Included in these responses are an acute inhibition of mRNA translation at the initiation step, a subsequent induction of various protein chaperones, and the recovery of mRNA translation. Separate, but closely related, stress response systems exist for the endoplasmic reticulum (ER), relating to the induction of specific "glucose-regulated proteins" (GRPs), and for the cytoplasm, pertaining to the induction of the "heat shock proteins" (HSPs). Activators of the ER stress response system, including Ca(2+)-mobilizing and thiol-reducing agents, are discussed and compared to activators of the cytoplasmic stress system, such as arsenite, heavy metal cations, and oxidants. An emerging integrative literature is reviewed that relates protein chaperones associated with cellular stress response systems to the coordinate regulation of translational initiation and protein processing. Background information is presented describing the roles of protein chaperones in the ER and cytoplasmic stress response systems and the relationships of chaperones and protein processing to the regulation of mRNA translation. The role of chaperones in regulating eIF-2 alpha kinase activities, eIF-2 cycling, and ribosomal loading on mRNA is emphasized. The putative role of GRP78 in coupling rates of translation to processing is modeled, and functional relationships between the HSP and GRP chaperone systems are discussed.
Collapse
Affiliation(s)
- C O Brostrom
- Department of Pharmacology, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, Piscataway 08854, USA
| | | |
Collapse
|
9
|
Satyamoorthy K, Howe CC. The mouse elongation factor-2 gene: isolation and characterization of the promoter. DNA Cell Biol 1997; 16:401-12. [PMID: 9150427 DOI: 10.1089/dna.1997.16.401] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Elongation factor 2 (EF-2) is a protein involved in peptide chain elongation in eukaryotes. We isolated the mouse EF-2 gene and characterized its promoter. We showed that the majority of enhancer elements were located within 500 bp of the flanking sequence and identified a factor binding site sequence (CGTCACGTGACGC) located between nucleotides -58 and -47 containing two CGTCA motifs separated by two nucleotides. The motif represents a half-site for binding of the cAMP response element (CRE) binding protein (CREB). Mutation analysis indicated that the presence of one CGTCA site alone conferred cAMP inducibility, but the presence of one or two CGTCA sites and spacing nucleotides elicited cAMP-independent, constitutive expression. UV cross-linking and DNA affinity chromatography revealed that three 40-, 43-, and 65-kD proteins bound to the CRE-like element. Of these, the 65-kD protein was unique to the CRE-like element. The 40-kD protein was ATF1 and the 43-kD protein with the molecular size of CREB was not CREB, on the basis of reactivity to their respective antibodies. Because ATF1 responds poorly to cAMP induction, it is likely the contributor to the constitutive expression rather than inductive expression of the CRE-like element, and, thus, the EF-2 gene.
Collapse
|
10
|
Luo SF, Chiu CT, Tsao HL, Fan LW, Tsai CT, Pan SL, Yang CM. Effect of forskolin on bradykinin-induced calcium mobilization in cultured canine tracheal smooth muscle cells. Cell Signal 1997; 9:159-67. [PMID: 9113415 DOI: 10.1016/s0898-6568(96)00136-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The effects of increases in intracellular adenosine 3':5'-cyclic monophosphate (cyclic AMP) on bradykinin (BK)-induced generation of inositol phosphates (IPs) and Ca2+ mobilization were investigated in canine cultured tracheal smooth muscle cells (TSMCs). Pretreatment of TSMCs with either forskolin or dibutyryl cyclic AMP attenuated BK-stimulated responses. The inhibitory effects of these agents produced both a depression of the maximal response and a shift to the right of the concentration-response curves of BK. The water-soluble forskolin analogue L-858051, 7-deacetyl-7 beta-(r-N-methylpiperazino)-butyryl forskolin, significantly attenuated BK-stimulated IPs accumulation, while 1,9-dideoxy forskolin, an inactive forskolin, had little effect on IPs response. Moreover, SQ-22536, 9-(tetrahydro-2-furanyl)-9-H-purin-6-amine, an inhibitor of adenylate cyclase, and both H-89, N-(2-aminoethyl)-5-isoquinolinesulfonamide, and HA-1004, N-(2-guanidinoethyl)-5-isoquinolinesulfonamide, inhibitors of cyclic AMP-dependent protein kinase (PKA), reversed the ability of forskolin to attenuate BK-stimulated IPs accumulation. The KD and Bmax, values of the BK receptor for [3H]BK binding were not significantly changed by forskolin treatment for 30 min and 4 h. The AlF4(-)-induced IPs accumulation was attenuated by forskolin, indicating that G protein(s) are directly activated by AlF4- and uncoupled to phospholipase C by forskolin treatment. These results suggest that activation of cyclic AMP/PKA might inhibit the BK-stimulated PI breakdown and consequently reduce the [Ca2+]i increases or inhibit independently both responses, which is distal to the BK receptor in canine cultured TSMCs.
Collapse
Affiliation(s)
- S F Luo
- Department of Internal Medicine, Chang Gung College of Medicine and Technology, Kwei-San, Tao-Yuan, Taiwan
| | | | | | | | | | | | | |
Collapse
|
11
|
Hait WN, Ward MD, Trakht IN, Ryazanov AG. Elongation factor-2 kinase: immunological evidence for the existence of tissue-specific isoforms. FEBS Lett 1996; 397:55-60. [PMID: 8941713 DOI: 10.1016/s0014-5793(96)01140-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
eEF-2 kinase is a ubiquitous Ca2+/calmodulin-dependent protein kinase that is specific for protein synthesis elongation factor-2 (eEF-2). This study describes an improved procedure for the purification of eEF-2 kinase from rabbit reticulocyte lysate. The eEF-2 kinase preparation was used to raise polyclonal antibodies, which immunoprecipitated eEF-2 kinase protein and activity from rabbit reticulocyte lysate. The antibodies recognized a single 103 kDa band in extracts from several cell lines including NIH 3T3, PC12, C6 glioma, HeLa, and MCF-7 breast carcinoma. However, there was no immunoreactivity in extracts of rabbit or bovine liver or rabbit kidney despite the presence of abundant eEF-2 kinase activity in these tissues. Exposure of PC12 cells to nerve growth factor (NGF) resulted in rapid down-regulation of eEF-2 kinase activity and a decrease in immunoreactivity. After 24 h of incubation with NGF, the activity of the kinase recovered to 80% of initial values. In contrast, the immunoreactivity of eEF-2 kinase continued to decrease. These data suggest that tissue-specific isoforms of eEF-2 kinase may exist and that these isoforms may be regulated by growth factors.
Collapse
Affiliation(s)
- W N Hait
- Department of Pharmacology, University of Medicine and Dentistry of New Jersey/Robert Wood Johnson Medical School, Piscataway 08854, USA
| | | | | | | |
Collapse
|
12
|
Yang C, Tsao HL, Chiu CT, Fan LW, Yu SM. Regulation of 5-hydroxytryptamine-induced calcium mobilization by cAMP-elevating agents in cultured canine tracheal smooth muscle cells. Pflugers Arch 1996; 432:708-16. [PMID: 8764973 DOI: 10.1007/s004240050189] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The effects of increases in cellular adenosine 3'5'-cyclic monophosphate (cAMP) on 5-hydroxytryptamine-(5-HT-) induced generation of inositol phosphates (IPs) and increases in intracellular Ca2+ ([Ca2+]i) were investigated using canine cultured tracheal smooth muscle cells (TSMCs). Cholera toxin and forskolin induced concentration- and time-dependent cAMP formation with half-maximal effects (-logEC50) produced at concentrations of 7.0 +/- 0.5 and 4.9 +/- 0.4 respectively. Pretreatment of TSMCs with either forskolin or dibutyryl cAMP inhibited 5-HT-stimulated responses. Even after treatment for 24h, these agents still inhibited the 5-HT-induced Ca2+ mobilization. The inhibitory effects of these agents produced both depression of the maximal response and a shift to the right of the concentration response curves of 5-HT. The water-soluble forskolin analogue L-858051 [7-deacetyl-7beta-(gamma-N-methylpiperazino)-butyryl forskolin] significantly inhibited the 5-HT-stimulated accumulation of IPs. In contrast, the addition of 1,9-dideoxy forskolin, an inactive forskolin analogue, had little effect on this response. Moreover, SQ-22536 [9-(tetrahydro-2-furanyl)-9-H-purin-6-amine], an inhibitor of adenylate cyclase, and both H-89 [N-(2-aminoethyl)-5-isoquinolinesulphonamide] and HA-1004[N-(2-guanidinoethyl)-5-isoquinolinesulphonamide], inhibitors of cAMP-dependent protein kinase (PKA), attenuated the ability of forskolin to inhibit the 5-HT-stimulated accumulation of IPs. These results suggest that activation of cAMP/PKA was involved in these inhibitory effects of forskolin. The AlF4--induced accumulation of IPs was inhibited by forskolin, suggesting that G protein(s) are directly activated by AlF4-- and uncoupled from phospholipase C by forskolin treatment. These results suggest that activation of cAMP/PKA might inhibit the 5-HT-stimulated phosphoinositide breakdown and consequently reduce the [Ca2+]i increase or inhibit both responses independently.
Collapse
Affiliation(s)
- C Yang
- Cellular and Molecular Pharmacology Laboratory, Department of Pharmacology, Chang Gung College of Medicine and Technology, Kwei-San, Tao-Yuan, Taiwan
| | | | | | | | | |
Collapse
|
13
|
Yang CM, Hsu MC, Tsao HL, Chiu CT, Ong R, Hsieh JT, Fan LW. Effect of cAMP elevating agents on carbachol-induced phosphoinositide hydrolysis and calcium mobilization in cultured canine tracheal smooth muscle cells. Cell Calcium 1996; 19:243-54. [PMID: 8732264 DOI: 10.1016/s0143-4160(96)90025-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The effects of increases in intracellular adenosine 3',5'-cyclic monophosphate (cAMP) on carbachol-induced generation of inositol phosphates (IPs) and increases in intracellular Ca2+ ([Ca2+]i) were investigated in canine cultured tracheal smooth muscle cells (TSMCs). The cAMP elevating agents, cholera toxin (CTX) and forskolin, induced concentration- and time-dependent cAMP formation with half-maximal effects (-logEC50) at concentrations of 7.6 +/- 1.3 g/ml and 4.8 +/- 0.9 M, respectively. Forskolin caused a concentration-dependent inhibition of carbachol-induced increase in [Ca2+]i with half-maximal inhibition (-logEC50) at 5.2 +/- 0.7 M. Pretreatment of TSMCs with either CTX (10 micrograms/ml, 4 h), forskolin (10-100 microM, 30 min), or dibutyryl cAMP (1 mM, 30 min) inhibited carbachol-stimulated Ca2+ mobilization and IPs accumulation. The inhibitory effects of these agents produced both depression of the maximal response and a shift to the right of the concentration-response curve of carbachol without changing the EC50 values. After treatment with forskolin for 24 h, carbachol-induced IPs accumulation and Ca2+ mobilization were close to those of control group. SQ-22536 [9-(tetrahydro-2-furanyl)-9H-purin-6-amine, 10 microM], an inhibitor of adenylate cyclase, and HA-1004 [N-(2-guanidinoethyl)-5-isoquinolinesulfonamide hydrochloride, 50 microM], an inhibitor of cAMP-dependent protein kinase (PKA), attenuated the ability of forskolin to inhibit carbachol-induced IPs accumulation. Moreover, the inactive analogue of forskolin, 1,9-dideoxy forskolin, did not inhibit these responses evoked by carbachol, suggesting that activation of cAMP/PKA was involved in these inhibitory effects of forskolin. The KD and Bmax values of the muscarinic receptor (mAChR) for [3H]-N-methyl scopolamine binding were not significantly changed by forskolin treatment for 30 min and 24 h, suggesting that the inhibitory effect of forskolin is distal to the mAChR. The locus of this inhibition was further investigated by examining the effect of forskolin treatment on AIF4(-)-stimulated IPs accumulation in canine TSMCs. The AIF4(-)-induced response was inhibited by forskolin, supporting the notion that G protein(s) are directly activated by AIF4- and uncoupled to phospholipase C by forskolin treatment. We conclude that cAMP elevating agents inhibit carbachol-stimulated generation of IPs and Ca2+ mobilization in canine cultured TSMCs. Since generation of IPs and increases in [Ca2+]i are very early events in the activation of mAChRs, attenuation of these events by cAMP elevating agents might well contribute to the inhibitory effect of cAMP on tracheal smooth muscle formation.
Collapse
Affiliation(s)
- C M Yang
- Department of Pharmacology, Chang Gung College of Medicine and Technology, Taiwan
| | | | | | | | | | | | | |
Collapse
|
14
|
Nilsson A, Nygård O. Phosphorylation of eukaryotic elongation factor 2 in differentiating and proliferating HL-60 cells. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1268:263-8. [PMID: 7548224 DOI: 10.1016/0167-4889(95)00084-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Ca(2+)-and calmodulin-dependent protein kinase III (CaM PKIII) phosphorylates eukaryotic elongation factor 2 (eEF-2) in HL-60 cells. Dephosphorylation of the factor in these cells is catalyzed by phosphoprotein phosphatase 2A alone. Differentiation of the HL-60 cells by all-trans retinoic acid resulted in a reduced growth rate and a marked decrease in the intracellular concentration of eEF-2. During differentiation the activity of the eEF-2 kinase is gradually reduced and reaches 10% of that found in undifferentiated cells 5 days after the onset of differentiation. The capacity to dephosphorylate phospho-eEF-2 remained unaltered in the growth-arrested cells. Differentiation without reduced proliferation was induced in the HL-60 cells by interferon-gamma. Under these conditions, differentiation had no effect on the cellular content of eEF-2 or the ability to dephosphorylate phospho-eEF-2. However, the differentiated cells showed a dramatic decrease in the specific activity of the eEF-2 kinase. The results show that the cellular content of eEF-2 varies with the rate of proliferation and that the activity of the eEF-2 kinase is high in undifferentiated proliferating cells and decreases upon differentiation even under conditions of an unaltered growth rate.
Collapse
Affiliation(s)
- A Nilsson
- Department of Zoological Cell Biology, Arrhenius Laboratories E5, Stockholm University, Sweden
| | | |
Collapse
|
15
|
Nilsson A, Nygård O. Effect of oxidizing agents and haemin on the phosphorylation of eukaryotic elongation factor 2 in rabbit reticulocyte lysates. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1260:200-6. [PMID: 7841197 DOI: 10.1016/0167-4781(94)00198-c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Incubation of rabbit reticulocyte lysates in the absence of added haemin resulted in the phosphorylation of a 95 kDa protein. This protein was suggested to be elongation factor 2 (eEF-2) based on the following observations, (i) phosphorylation of the 95 kDa protein was Ca2+ and CaM-dependent. (ii) eEF-2 supplemented to the lysates became phosphorylated and co-migrated with the endogenous 95 kDa phosphoprotein upon electrophoresis in SDS gels. (iii) The tryptophane specific cleavage pattern obtained from the isolated 95 kDa phosphoprotein was identical to that of phosphorylated eEF-2. Phosphorylation of the 95 kDa protein was stimulated by oxidizing agents such as oxidized glutathione and NAD+ and inhibited by addition of haemin. The haemin concentration needed for 50% inhibition (IC50) was 2.5 microM. Haemin also had an inhibitory effect on eEF-2 phosphorylation in a system containing highly purified components (IC50 = 2 microM). In this system haemin inhibited phosphorylation of eEF-2 even in the presence of a 100-fold excess of beta-mercaptoethanol. Oxidizing agents had no effect on the kinase activity in the purified system.
Collapse
Affiliation(s)
- A Nilsson
- Department of Zoological Cell Biology, Arrhenius Laboratories E5, Stockholm University, Sweden
| | | |
Collapse
|
16
|
Gnegy ME. Calmodulin: effects of cell stimuli and drugs on cellular activation. PROGRESS IN DRUG RESEARCH. FORTSCHRITTE DER ARZNEIMITTELFORSCHUNG. PROGRES DES RECHERCHES PHARMACEUTIQUES 1995; 45:33-65. [PMID: 8545541 DOI: 10.1007/978-3-0348-7164-8_2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The activity, localization and cellular content of CaM can be regulated by drugs, hormones and neurotransmitters. Regulation of physiological responses of CaM can depend upon local Ca(2+)-entry domains in the cells and phosphorylation of CaM target proteins, which would either decrease responsiveness of CaM target enzymes or increase CaM availability for binding to other target proteins. Despite the abundance of CaM in many cells, persistent cellular activation by a variety of substances can lead to an increase in CaM, reflected both in the nucleus and other cellular compartments. Increases in CaM-binding proteins can accompany stimuli-induced increases in CaM. A role for CaM in vesicular or protein transport, cell morphology, secretion and other cytoskeletal processes is emerging through its binding to cytoskeletal proteins and myosins in addition to the more often investigated activation of target enzymes. More complete knowledge of the physiological regulation of CaM can lead to a greater understanding of its role in physiological processes and ways to alter its actions through pharmacology.
Collapse
Affiliation(s)
- M E Gnegy
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor 48103-0632, USA
| |
Collapse
|
17
|
Palfrey HC, Nairn AC. Calcium-dependent regulation of protein synthesis. ADVANCES IN SECOND MESSENGER AND PHOSPHOPROTEIN RESEARCH 1995; 30:191-223. [PMID: 7695990 DOI: 10.1016/s1040-7952(05)80008-4] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- H C Palfrey
- Department of Pharmacological and Physiological Sciences, University of Chicago, Illinois 60637
| | | |
Collapse
|
18
|
Albarracin C, Palfrey H, Duan W, Rao M, Gibori G. Prolactin regulation of the calmodulin-dependent protein kinase III elongation factor-2 system in the rat corpus luteum. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)37353-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
19
|
Rodrigo J, Uttenthal O, Bentura ML, Maeda N, Mikoshiba K, Martinez-Murillo R, Polak JM. Subcellular localization of the inositol 1,4,5-trisphosphate receptor, P400, in the vestibular complex and dorsal cochlear nucleus of the rat. Brain Res 1994; 634:191-202. [PMID: 8131069 DOI: 10.1016/0006-8993(94)91922-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The subcellular localization of the inositol 1,4,5-trisphosphate receptor protein, P400, was studied in the vestibular complex, an area to which Purkinje cells project, as well as in neurons of the dorsal cochlear nucleus and in ectopic Purkinje cells of adult rat brain. The receptor was demonstrated by electron microscopical immunocytochemistry using the avidin-biotin peroxidase complex procedure, with the monoclonal antibody 4C11 raised against mouse cerebellar inositol 1,4,5-trisphosphate receptor protein. Immunoreactivity was found in preterminal fibres and terminal boutons in the nuclei of the vestibular complex, generally associated with the subsurface systems and stacks or fragments of smooth endoplasmic reticulum. Ectopic Purkinje cells and cartwheel cells of the dorsal cochlear nucleus also displayed immunoreactivity, but this was much less intense in the latter. The results of the present study suggest that this receptor protein, involved in the release of Ca2+, is located in sites that enable it to influence the synthesis, transport and release of neurotransmitters.
Collapse
Affiliation(s)
- J Rodrigo
- Unidad de Neuroanatomía Funcional, Instituto Cajal, C.S.I.C., Madrid, Spain
| | | | | | | | | | | | | |
Collapse
|
20
|
Singh KR, Taylor LK, Campbell XZ, Fields AP, Neet KE. A bryostatin-sensitive protein kinase C required for nerve growth factor activity. Biochemistry 1994; 33:542-51. [PMID: 8286384 DOI: 10.1021/bi00168a020] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Nerve growth factor (NGF) stimulates rat pheochromocytoma cells (PC12) to differentiate into a neuronal-like cell that exhibits neurite extensions. The role of protein kinase C in signal transduction has been examined in PC12 cells treated with phorbol 12-myristate 13-acetate (PMA) and bryostatin, a macrocyclic lactone that activates protein kinase C at both the nuclear and the plasma membranes [Hocevar, B. A., & Fields, A. P. (1991) J. Biol. Chem. 266, 28-33]. In contrast to PMA down-regulation [Reinhold, D. S., & Neet, K. E. (1989) J. Biol. Chem. 264, 3538-3544], chronic (24 h) treatment with bryostatin blocked the formation of neurites in response to NGF or basic fibroblast-derived growth factor stimulation, but, like PMA, bryostatin did not block the induction of c-fos or c-jun protooncogenes by NGF. Chronic bryostatin treatment down-regulated protein kinase C activity in the cytosolic, membrane, and nuclear fractions. Acute (60 min) bryostatin or NGF treatment activated cytosolic and nuclear protein kinase C activity, suggesting possible translocation to the nucleus. Bryostatin did not induce neurite outgrowth, either alone or in combination with PMA. Thus, the bryostatin-sensitive protein kinase C is distinct from PMA- or K252a-sensitive kinases previously described. The bryostatin-sensitive protein kinase C is necessary, but not sufficient, for neurite outgrowth and acts in the nucleus in a manner independent of c-fos and c-jun transcription.
Collapse
Affiliation(s)
- K R Singh
- Department of Biological Chemistry, UHS/Chicago Medical School, Illinois 60064
| | | | | | | | | |
Collapse
|
21
|
Redpath NT, Proud CG. Molecular mechanisms in the control of translation by hormones and growth factors. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1220:147-62. [PMID: 8312359 DOI: 10.1016/0167-4889(94)90130-9] [Citation(s) in RCA: 84] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- N T Redpath
- Department of Biochemistry, School of Medical Sciences, University of Bristol, UK
| | | |
Collapse
|
22
|
Brady M, Palfrey H. Rapid and sustained phosphorylation of a calmodulin-binding protein (CaM-BP100) in NGF-treated PC12 cells. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(17)46797-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
|
23
|
Purification and characterization of calmodulin-dependent protein kinase III from rabbit reticulocytes and rat pancreas. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(19)38667-3] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
|
24
|
Smailov SK, Lee AV, Iskakov BK. Study of phosphorylation of translation elongation factor 2 (EF-2) from wheat germ. FEBS Lett 1993; 321:219-23. [PMID: 8386679 DOI: 10.1016/0014-5793(93)80112-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Phosphorylation of elongation factor 2 (EF-2) by specific Ca2+/calmodulin-dependent kinase is considered as a possible mechanism of regulation of protein biosynthesis in animal cells at the level of polypeptide chain elongation. In this report we show that wheat germ EF-2 can be intensively phosphorylated by the rabbit reticulocyte EF-2 kinase. Phosphorylation results in inhibition of the activity of plant EF-2 in poly(U)-dependent cell-free translation system. Thus, the activity of EF-2 in plant cells can be potentially regulated by phosphorylation. However, we could not detect endogenous EF-2 kinase activity in wheat germ either in vitro or in vivo. Furthermore, EF-2 kinase activity is not displayed in different organs of wheat and other higher plants.
Collapse
Affiliation(s)
- S K Smailov
- Institute of Molecular Biology and Biochemistry, Kazakh Academy of Sciences, Alma-Ata, Kazakhstan
| | | | | |
Collapse
|
25
|
Johnson G, Gotlib J, Haroutunian V, Bierer L, Nairn AC, Merril C, Wallace W. Increased phosphorylation of elongation factor 2 in Alzheimer's disease. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1992; 15:319-26. [PMID: 1331687 DOI: 10.1016/0169-328x(92)90124-t] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Elongation factor 2 (EF-2) is a phosphoprotein that mediates the translocation step of elongation during protein synthesis. We investigated its phosphorylation to characterize translational regulation of gene expression in Alzheimer's disease. EF-2 was identified on two-dimensional (2D) gels of brain homogenates by analyzing immunoblots with EF-2-specific antibody (M(r) 96,000; pI 6.8). Four distinct charge variant isoforms were observed. We identified the two most acidic isoforms as being the phosphorylated forms by incorporation of radiolabeled phosphate. The phosphorylation of EF-2 in control and Alzheimer's disease (AD) brain was directly measured as the distribution of the four polypeptides on silver stained 2D gels. The ratio of the phosphorylated forms to unphosphorylated forms was elevated 45% in AD homogenates compared to controls (1.07 +/- 0.18; n = 9 vs 0.73 +/- 0.20; n = 6; P less than 0.004) which indicated an increased phosphorylation of AD EF-2. The phosphorylation exhibited specificity to the disease in that it was observed in affected areas (cortex and hippocampus) but not in an unaffected area (thalamus) of the same brains. Because phosphorylation of EF-2 inhibits protein synthesis, the observed AD-associated phosphorylation of EF-2 is consistent with the reduced in vitro activity of polysomes isolated from AD tissues that we have previously reported.
Collapse
Affiliation(s)
- G Johnson
- Laboratory of Biochemical Genetics, National Institute of Mental Health, St. Elizabeth's Hospital, Washington, DC
| | | | | | | | | | | | | |
Collapse
|
26
|
Redpath NT. High-resolution one-dimensional polyacrylamide gel isoelectric focusing of various forms of elongation factor-2. Anal Biochem 1992; 202:340-3. [PMID: 1519762 DOI: 10.1016/0003-2697(92)90115-n] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
A system for analyzing covalent modifications of elongation factor-2 (eEF-2) by one-dimensional isoelectric focusing in slab polyacrylamide gels is described. Depending on the degree of phosphorylation, four species of eEF-2 could be resolved corresponding to the un-, mono-, bis-, and trisphosphorylated factor. Furthermore, the degree of ADP-ribosylation of the protein could also be assessed by this method. It was also shown that an acidic isoform of eEF-2 exists which appears not to be artifactual and that the relative level of this isoform appeared to vary between different cell types. By Western blotting the gels and using an antibody against eEF-2 it is possible to assess the state of phosphorylation of the factor in cells.
Collapse
Affiliation(s)
- N T Redpath
- Department of Biochemistry, School of Medical Sciences, University of Bristol, United Kingdom
| |
Collapse
|
27
|
Bai G, Nichols RA, Weiss B. Cyclic AMP selectively up-regulates calmodulin genes I and II in PC12 cells. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1130:189-96. [PMID: 1314092 DOI: 10.1016/0167-4781(92)90527-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Calmodulin is encoded by three genes in rat tissues, which collectively transcribe five different mRNAs. We showed previously that the pheochromocytoma cell line, PC12, expresses all five of these mRNAs and that treating PC12 cells with nerve growth factor differentially induces the calmodulin mRNAs; the greatest increase was seen by 24 h in the 1.4 kb transcript from calmodulin gene II. In the present study we found that treating PC12 cells with dibutyryl cyclic AMP also differentially increased the levels of the calmodulin mRNAs. However, dibutyryl cyclic AMP produced increases as early as 3 to 6 h, with the greatest increase (about 3-fold) being seen in the level of the 1.7 kb mRNA transcribed from calmodulin gene I. The transcripts of 4.1 kb (calmodulin gene I) and 1.4 kb (calmodulin gene II) were also increased, but the 2.3 kb transcript from calmodulin gene III remained stable. Another cyclic AMP analogue, chlorophenylthio cyclic AMP, produced effects similar to those of dibutyryl cyclic AMP, but dibutyryl cyclic GMP did not. Pretreatment with cycloheximide blocked the increase in the 4.1 kb calmodulin mRNA induced by dibutyryl cyclic AMP, but only partially blocked the increase in the 1.4 kb and 1.7 kb transcripts. Phorbol 12-myristate 13-acetate, which can induce some cyclic AMP responsive genes, failed to significantly change the levels of any of the calmodulin mRNAs. These studies show that, like nerve growth factor, cyclic AMP can selectively up-regulate the transcripts from calmodulin genes in PC12 cells, but the time-course and type of transcripts induced by cyclic AMP are distinct. These results suggest that the mechanisms by which these two agents alter the calmodulin transcripts are different.
Collapse
Affiliation(s)
- G Bai
- Department of Pharmacology, Medical College of Pennsylvania, Philadelphia 19129
| | | | | |
Collapse
|
28
|
Affiliation(s)
- C G Proud
- Department of Biochemistry, School of Medical Sciences, University of Bristol, England
| |
Collapse
|
29
|
Phosphorylation regulates the activity of the eEF-2-specific Ca(2+)- and calmodulin-dependent protein kinase III. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)55316-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
|
30
|
Price NT, Redpath NT, Severinov KV, Campbell DG, Russell JM, Proud CG. Identification of the phosphorylation sites in elongation factor-2 from rabbit reticulocytes. FEBS Lett 1991; 282:253-8. [PMID: 2037042 DOI: 10.1016/0014-5793(91)80489-p] [Citation(s) in RCA: 96] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The sites in eukaryotic elongation factor eEF-2 phosphorylated by the Ca2+/calmodulin-dependent eEF-2 kinase in vitro have been identified. The kinase catalysed the rapid incorporation of one mol of phosphate per mol eEF-2 and the slower incorporation of a second mol. All the phosphorylation sites in eEF-2 are contained in the CNBr fragment corresponding to residues 22-155. Tryptic digestion of phosphorylated eEF-2 yielded 3 phosphopeptides, one being unique to monophosphorylated eEF-2. The phosphorylation sites were identified as threonine residues 56 and 58, the former being more rapidly phosphorylated. Ala-Gly-Glu-Thr-Phe-Thr56-Asp-Thr58-Arg. The same sites are labelled in eEF-2 isolated from reticulocyte lysates.
Collapse
Affiliation(s)
- N T Price
- Department of Biochemistry, School of Medical Sciences, University of Bristol, UK
| | | | | | | | | | | |
Collapse
|
31
|
Nilsson A, Carlberg U, Nygård O. Kinetic characterisation of the enzymatic activity of the eEF-2-specific Ca2(+)-and calmodulin-dependent protein kinase III purified from rabbit reticulocytes. EUROPEAN JOURNAL OF BIOCHEMISTRY 1991; 195:377-83. [PMID: 1671764 DOI: 10.1111/j.1432-1033.1991.tb15716.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The Ca2(+)-and calmodulin-dependent protein kinase III, which specifically phosphorylates the eukaryotic elongation factor 2 (eEF-2), has been purified to apparent homogeneity from the post-ribosomal fraction of rabbit reticulocytes by an efficient four-step method. The method results in a more than 4000-fold purification of the enzyme. SDS-gel electrophoresis showed that the purified kinase contained only one polypeptide with the apparent molecular mass of 90 kDa. The kinase activity was associated with the 90-kDa protein as shown by analyzing the phosphorylating activity of SDS gel electrophoretically purified protein electroblotted to nitrocellulose membranes. The purified kinase was dependent on Ca2+, Mg2+ and calmodulin for activity. Kinetic analysis of the phosphorylation reaction indicates that the turnover number of the kinase was approximately 1 s-1. The Km for the two substrates ATP and eEF-2 was calculated to be approximately 100 microM and 10 microM, respectively. The activity of the kinase was competitively inhibited by cAMP. The inhibition constant Ki (0.5 mM) was found to be in the same order of magnitude as that calculated for the competitive product inhibition caused by ADP. GTP was ten-times less efficient as competitor, indicating that the kinase had a preference for adenosine nucleotides. Phosphorylation of eEF-2 did not interfere with the diphtheria-toxin-catalysed ADP-ribosylation of the factor nor did ADP-ribosylation inhibit phosphorylation.
Collapse
Affiliation(s)
- A Nilsson
- Department of Cell Biology, Stockholm University, Sweden
| | | | | |
Collapse
|
32
|
Hidaka H, Watanabe M, Kobayashi R. Properties and use of H-series compounds as protein kinase inhibitors. Methods Enzymol 1991; 201:328-39. [PMID: 1658551 DOI: 10.1016/0076-6879(91)01029-2] [Citation(s) in RCA: 102] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
|
33
|
Gillette R, Gillette M, Lipeski L, Connor J. pH-sensitive, Ca2+/calmodulin-dependent phosphorylation of unique protein in molluscan nervous system. BIOCHIMICA ET BIOPHYSICA ACTA 1990; 1036:207-12. [PMID: 2257277 DOI: 10.1016/0304-4165(90)90036-v] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Intracellular pH and Ca2+ are prominent co-regulators of neuron excitability that act on ion channels. In looking for a possible mechanism of their action, we tested their combinatorial effect on the phosphorylation state of nervous system proteins. 32PO4 labelling in endogenous phosphorylation reactions of homogenates of nervous tissue of the sea-slug Pleurobranchaea showed steep pH sensitivity in protein migrating at a molecular mass of 108 kDa with pI 6.9-7.0 (pp108). Phosphorylation of pp108 was highest below reaction pH 7.0 and declined steeply as pH rose to 7.4 pp108 phosphorylation was Ca2+/calmodulin-dependent. pp108 constituted a significant part of the total protein (0.15%) and phosphoprotein (8.9%) of the nervous system. The specifically and uniquely combinatorial pH and Ca2+ sensitivity of the phosphorylation of pp108, and its relative abundance, suggest that it could mediate integrated actions of H+ and Ca2+ in the molluscan neuron.
Collapse
Affiliation(s)
- R Gillette
- Department of Physiology and Biophysics, University of Illinois, Urbana 61801
| | | | | | | |
Collapse
|
34
|
Tsao H, Aletta J, Greene L. Nerve growth factor and fibroblast growth factor selectively activate a protein kinase that phosphorylates high molecular weight microtubule-associated proteins. Detection, partial purification, and characterization in PC12 cells. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(18)55420-x] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
35
|
Nygård O, Nilsson L. Translational dynamics. Interactions between the translational factors, tRNA and ribosomes during eukaryotic protein synthesis. EUROPEAN JOURNAL OF BIOCHEMISTRY 1990; 191:1-17. [PMID: 2199194 DOI: 10.1111/j.1432-1033.1990.tb19087.x] [Citation(s) in RCA: 124] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- O Nygård
- Department of Cell Biology, Wenner-Gren Institute, University of Stockholm, Sweden
| | | |
Collapse
|
36
|
Nikodijevic B, Creveling CR, Koizumi S, Guroff G. Nerve growth factor and K-252a increase catecholamine release from PC12 cells. J Neurosci Res 1990; 26:288-95. [PMID: 2118962 DOI: 10.1002/jnr.490260304] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
PC12 cells are a nerve growth factor-responsive clone derived from a rat pheochromocytoma. The cells contain catecholamines and secrete them in response to depolarizing stimuli and cholinergic agonists. Treatment of the cells with nerve growth factor produces a number of very rapid changes, including the structural rearrangement of the cell membrane, the generation of a number of different second messengers, and the phosphorylation of several proteins. The present studies show that nerve growth factor treatment increases the release of dopamine and norepinephrine from the cells within a few minutes and does so independently of its effect on their metabolism. The experiments indicate that this effect on nerve growth factor is dependent on the presence of extracellular calcium and can be blocked by calcium channel antagonists. K-252a, an alkaloid-like material, usually found to inhibit the actions of nerve growth factor on PC12 cells, also increases the release of catecholamines under these conditions.
Collapse
Affiliation(s)
- B Nikodijevic
- Section on Growth Factors, National Institute of Child Health and Human Development, Bethesda, Maryland 20892
| | | | | | | |
Collapse
|
37
|
Kondratyev AD, Popova ON, Severin SE, Choladze MA, Shmyrev II, Tubasheva IA, Zotova EE, Posypanova GA, Severin ES. Nerve growth factor stimulates protein kinase C translocation in PC12 cells. FEBS Lett 1990; 264:75-7. [PMID: 2186928 DOI: 10.1016/0014-5793(90)80768-e] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The effect of nerve growth factor (NGF) on the activity and intracellular localization of protein kinase C (PKC) in pheochromocytoma PC12 cells was studied. By using immunoblotting, immunofluorescence method and phorbol ester binding, NGF was found to induce PKC translocation from the cytoplasm into the cell membrane. This process was accompanied by an increase in the protein kinase activity in the membrane fraction. Translocation was completely blocked by H-7, a protein kinase inhibitor potentiating the neurite-stimulating activity of NGF.
Collapse
Affiliation(s)
- A D Kondratyev
- Research Center of Molecular Diagnostics, USSR Ministry of Health, Moscow
| | | | | | | | | | | | | | | | | |
Collapse
|
38
|
Brady MJ, Nairn AC, Wagner JA, Palfrey HC. Nerve growth factor-induced down-regulation of calmodulin-dependent protein kinase III in PC12 cells involves cyclic AMP-dependent protein kinase. J Neurochem 1990; 54:1034-9. [PMID: 1689374 DOI: 10.1111/j.1471-4159.1990.tb02354.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Treatment of PC12 cells with nerve growth factor (NGF), epidermal growth factor (EGF), or agents that raise intracellular cyclic AMP (cAMP) levels (e.g., forskolin) reduces the activity of calmodulin-dependent protein kinase III (CaM-PK III) over a period of 8 h. The mechanism of this effect of NGF has now been examined in more detail, making use of a mutant PC12 cell line (A126-1B2) that is deficient in cAMP-dependent protein kinase activity. Control experiments showed that A126-1B2 cells retain other NGF-mediated responses (e.g., the induction of ornithine decarboxylase, a cAMP-independent event) and contain a complement of CaM-PK III and its substrate, elongation factor-2, comparable to that of wild-type cells. The ability of NGF or forskolin, but not of EGF, to down-regulate CaM-PK III was markedly attenuated in A126-1B2 compared to wild-type cells. Treatment of wild-type cells with the cAMP phosphodiesterase inhibitor, isobutylmethylxanthine, enhanced the effects of NGF, but not of EGF. The possibility that NGF led to a stimulation of cAMP-dependent protein kinase activity in wild-type cells was assessed by measurement of the "activation ratio" (-cAMP/+cAMP) of this enzyme before and at various times after NGF addition. A small, but significant, increase in the activation ratio from 0.3 to 0.48 was observed, reaching a peak 5 min after NGF treatment. EGF had no effect on the activation ratio in wild-type cells.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
Affiliation(s)
- M J Brady
- Department of Pharmacological and Physiological Sciences, University of Chicago, IL 60637
| | | | | | | |
Collapse
|
39
|
Tokumitsu H, Chijiwa T, Hagiwara M, Mizutani A, Terasawa M, Hidaka H. KN-62, 1-[N,O-bis(5-isoquinolinesulfonyl)-N-methyl-L-tyrosyl]-4-phenylpiperazi ne, a specific inhibitor of Ca2+/calmodulin-dependent protein kinase II. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)39565-1] [Citation(s) in RCA: 287] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
40
|
Stimulation by glia maturation factor of Ca2+-dependent phosphorylation of Mr 100 k protein in rat glioblasts. Neurochem Int 1990; 17:559-71. [DOI: 10.1016/0197-0186(90)90044-t] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/1989] [Accepted: 04/02/1990] [Indexed: 11/20/2022]
|
41
|
Ross CA, Meldolesi J, Milner TA, Satoh T, Supattapone S, Snyder SH. Inositol 1,4,5-trisphosphate receptor localized to endoplasmic reticulum in cerebellar Purkinje neurons. Nature 1989; 339:468-70. [PMID: 2542801 DOI: 10.1038/339468a0] [Citation(s) in RCA: 364] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Inositol 1,4,5-trisphosphate (InsP3) mediates the effects of several neurotransmitters, hormones and growth factors by mobilizing Ca2+ from a vesicular, non-mitochondrial intracellular store. Many studies have indirectly suggested the endoplasmic reticulum (ER) to be the site of InsP3 action, though some have implicated the plasma membrane or a newly described smooth surfaced structure, termed the calciosome. Using antibodies directed against a purified InsP3-receptor glycoprotein, of relative molecular mass 260,000, in electron microscope immunocytochemical studies of rat cerebellar Purkinje cells, we have now localized the InsP3 receptor to ER, including portions of the rough endoplasmic reticulum, a population of smooth-membrane-bound organelles (smooth ER), a portion of subplasmalemmal cisternae and the nuclear membrane, but not to mitochondria or the cell membrane. These results suggest that in cerebellar Purkinje cells, InsP3-induced intracellular calcium release is not the property of a single organelle, but is effected by specialized portions of both rough and smooth ER, and possibly by other smooth surfaced structures. The present findings are the first immunocytochemical demonstration of an InsP3 receptor within a cell.
Collapse
Affiliation(s)
- C A Ross
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | | | | | | | | | | |
Collapse
|
42
|
Regulation of Protein Kinase C by Nerve Growth Factor, Epidermal Growth Factor, and Phorbol Esters in PC12 Pheochromocytoma Cells. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)81841-5] [Citation(s) in RCA: 149] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
|
43
|
The Lack of a Role for Protein Kinase C in Neurite Extension and in the Induction of Ornithine Decarboxylase by Nerve Growth Factor in PC12 Cells. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)94099-8] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
|
44
|
Brostrom MA, Lin X, Cade C, Gmitter D, Brostrom CO. Loss of a Calcium Requirement for Protein Synthesis in Pituitary Cells following Thermal or Chemical Stress. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)94234-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
45
|
Mackie KP, Nairn AC, Hampel G, Lam G, Jaffe EA. Thrombin and Histamine Stimulate the Phosphorylation of Elongation Factor 2 in Human Umbilical Vein Endothelial Cells. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)94250-x] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
|
46
|
Eveleth DD. Nerve growth factor receptors: structure and function. IN VITRO CELLULAR & DEVELOPMENTAL BIOLOGY : JOURNAL OF THE TISSUE CULTURE ASSOCIATION 1988; 24:1148-53. [PMID: 2850295 DOI: 10.1007/bf02624182] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- D D Eveleth
- Department of Biological Chemistry, California College of Medicine, University of California, Irvine 92717
| |
Collapse
|
47
|
Ryazanov AG, Shestakova EA, Natapov PG. Phosphorylation of elongation factor 2 by EF-2 kinase affects rate of translation. Nature 1988; 334:170-3. [PMID: 3386756 DOI: 10.1038/334170a0] [Citation(s) in RCA: 342] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A new Ca2+/calmodulin-dependent protein kinase has been recently discovered in mammalian cells. The major substrate of this kinase, a protein of relative molecular mass (Mr) approximately equal to 100,000 (100K), has been identified as elongation factor 2 (EF-2), which participates in protein synthesis. The in vivo activity of the EF-2 kinase depends upon growth factors and other agents affecting the level of Ca2+ and cAMP. Its effect on EF-2 activity, however, remained obscure. This work shows that the phosphorylation of EF-2 by the EF-2 kinase results in a drastic inhibition of polyphenylalanine synthesis in poly(U)-directed translation. Phosphorylated EF-2 is completely inactive in translation and, moreover, inhibits the activity of non-phosphorylated EF-2. Dephosphorylation of EF-2 by phosphatase restores its activity. Hence, the phosphorylation of EF-2 directly affects the elongation stage of translation and thus represents a novel mechanism of translational control.
Collapse
Affiliation(s)
- A G Ryazanov
- Institute of Protein Research, Academy of Sciences of the USSR, Moscow Region
| | | | | |
Collapse
|
48
|
Identification of the major Mr 100,000 substrate for calmodulin-dependent protein kinase III in mammalian cells as elongation factor-2. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)45377-x] [Citation(s) in RCA: 269] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
|