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Ashok S, Ramachandra Rao S. Updates on protein-prenylation and associated inherited retinopathies. FRONTIERS IN OPHTHALMOLOGY 2024; 4:1410874. [PMID: 39026984 PMCID: PMC11254824 DOI: 10.3389/fopht.2024.1410874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2024] [Accepted: 06/13/2024] [Indexed: 07/20/2024]
Abstract
Membrane-anchored proteins play critical roles in cell signaling, cellular architecture, and membrane biology. Hydrophilic proteins are post-translationally modified by a diverse range of lipid molecules such as phospholipids, glycosylphosphatidylinositol, and isoprenes, which allows their partition and anchorage to the cell membrane. In this review article, we discuss the biochemical basis of isoprenoid synthesis, the mechanisms of isoprene conjugation to proteins, and the functions of prenylated proteins in the neural retina. Recent discovery of novel prenyltransferases, prenylated protein chaperones, non-canonical prenylation-target motifs, and reversible prenylation is expected to increase the number of inherited systemic and blinding diseases with aberrant protein prenylation. Recent important investigations have also demonstrated the role of several unexpected regulators (such as protein charge, sequence/protein-chaperone interaction, light exposure history) in the photoreceptor trafficking of prenylated proteins. Technical advances in the investigation of the prenylated proteome and its application in vision research are discussed. Clinical updates and technical insights into known and putative prenylation-associated retinopathies are provided herein. Characterization of non-canonical prenylation mechanisms in the retina and retina-specific prenylated proteome is fundamental to the understanding of the pathogenesis of protein prenylation-associated inherited blinding disorders.
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Affiliation(s)
- Sudhat Ashok
- Department of Ophthalmology, Jacobs School of Medicine and Biomedical Sciences, State University of New York, University at Buffalo, Buffalo, NY, United States
| | - Sriganesh Ramachandra Rao
- Department of Ophthalmology, Jacobs School of Medicine and Biomedical Sciences, State University of New York, University at Buffalo, Buffalo, NY, United States
- Neuroscience Program, Jacobs School of Medicine and Biomedical Sciences, State University of New York, University at Buffalo, Buffalo, NY, United States
- Research Service, VA Western New York Healthcare System, Buffalo, NY, United States
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2
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Seo J, Hwang H, Choi Y, Jung S, Hong JH, Yoon BJ, Rhim H, Park M. Myristoylation-dependent palmitoylation of cyclin Y modulates long-term potentiation and spatial learning. Prog Neurobiol 2022; 218:102349. [PMID: 36030931 DOI: 10.1016/j.pneurobio.2022.102349] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 07/13/2022] [Accepted: 08/22/2022] [Indexed: 11/16/2022]
Abstract
Many psychiatric disorders accompany deficits in cognitive functions and synaptic plasticity, and abnormal lipid modifications of neuronal proteins are associated with their pathophysiology. Lipid modifications, including palmitoylation and myristoylation, play crucial roles in the subcellular localization and trafficking of proteins. Cyclin Y (CCNY), enriched in the postsynaptic compartment, acts as an inhibitory modulator of functional and structural long-term potentiation (LTP) in the hippocampal neurons. However, cellular and molecular mechanisms underlying CCNY-mediated inhibitory functions in the synapse remain largely unknown. Here, we report that myristoylation located CCNY to the trans-Golgi network (TGN), and subsequent palmitoylation directed the myristoylated CCNY from the TGN to the synaptic cell surface. This myristoylation-dependent palmitoylation of CCNY was required for the inhibitory role of CCNY in excitatory synaptic transmission, activity-induced dynamics of AMPA receptors and PSD-95, LTP, and spatial learning. Furthermore, spatial learning significantly reduced palmitoyl- and myristoyl-CCNY levels, indicating that spatial learning lowers the synaptic abundance of CCNY. Our findings provide mechanistic insight into how CCNY is clustered adjacent to postsynaptic sites where it could play its inhibitory roles in synaptic plasticity and spatial learning.
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Affiliation(s)
- Jiyeon Seo
- Brain Science Institute, Korea Institute of Science and Technology, Seoul 02792, South Korea
| | - Hongik Hwang
- Brain Science Institute, Korea Institute of Science and Technology, Seoul 02792, South Korea
| | - Yuri Choi
- Brain Science Institute, Korea Institute of Science and Technology, Seoul 02792, South Korea
| | - Sunmin Jung
- Brain Science Institute, Korea Institute of Science and Technology, Seoul 02792, South Korea
| | - Jung-Hwa Hong
- Brain Science Institute, Korea Institute of Science and Technology, Seoul 02792, South Korea; Department of Life Sciences, Korea University, Seoul 02841, South Korea
| | - Bong-June Yoon
- Department of Life Sciences, Korea University, Seoul 02841, South Korea
| | - Hyewhon Rhim
- Brain Science Institute, Korea Institute of Science and Technology, Seoul 02792, South Korea; Division of Bio-Medical Science & Technology, KIST School, Korea University of Science and Technology, Seoul 02792, South Korea
| | - Mikyoung Park
- Brain Science Institute, Korea Institute of Science and Technology, Seoul 02792, South Korea; Division of Bio-Medical Science & Technology, KIST School, Korea University of Science and Technology, Seoul 02792, South Korea.
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3
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Wu H, Scholten A, Einwich A, Mouritsen H, Koch KW. Protein-protein interaction of the putative magnetoreceptor cryptochrome 4 expressed in the avian retina. Sci Rep 2020; 10:7364. [PMID: 32355203 PMCID: PMC7193638 DOI: 10.1038/s41598-020-64429-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 04/16/2020] [Indexed: 11/15/2022] Open
Abstract
Migratory birds can sense the Earth’s magnetic field and use it for orientation over thousands of kilometres. A light-dependent radical-pair mechanism associated with the visual system is currently discussed as the underlying mechanism of the magnetic compass sense. The blue light receptor cryptochrome 4 (Cry4) is considered as the most likely primary sensory protein that detects the geomagnetic field. Since the protein interaction partners of Cry4 are completely unknown at present, here, we aim to identify potential candidate interaction partners of Cry4 in the avian retina. We used the yeast-two-hybrid system to screen avian cDNA libraries for possible interaction partners of Cry4 in the European robin. The UAS-GAL yeast two hybrid system was applied to confirm a group of candidate Cry4 interaction partners. Six proteins were found to be particularly promising candidates for interacting with European robin Cry4. The identified genes code for guanine nucleotide-binding protein G(t) subunit alpha-2 (GNAT2), long-wavelength-sensitive opsin (LWS, also called iodopsin), guanine nucleotide-binding protein subunit gamma 10 (GNG10), potassium voltage-gated channel subfamily V member 2 (KCNV2), retinol binding protein 1 (RBP1) and retinal G protein-coupled receptor (RGR). All genes are known to be expressed in vertebrate retinae of different species. We conclude by discussing putative signalling pathways that could connect cryptochrome 4 to one or more of these 6 candidates.
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Affiliation(s)
- Haijia Wu
- Department of Neuroscience, Division of Biochemistry, University of Oldenburg, D-26111, Oldenburg, Germany
| | - Alexander Scholten
- Department of Neuroscience, Division of Biochemistry, University of Oldenburg, D-26111, Oldenburg, Germany
| | - Angelika Einwich
- Department of Biology and Environmental Sciences, Neurosensorics/Animal Navigation, University of Oldenburg, D-26111, Oldenburg, Germany
| | - Henrik Mouritsen
- Department of Biology and Environmental Sciences, Neurosensorics/Animal Navigation, University of Oldenburg, D-26111, Oldenburg, Germany.,Research Center for Neurosensory Sciences, University of Oldenburg, 26111, Oldenburg, Germany
| | - Karl-Wilhelm Koch
- Department of Neuroscience, Division of Biochemistry, University of Oldenburg, D-26111, Oldenburg, Germany. .,Research Center for Neurosensory Sciences, University of Oldenburg, 26111, Oldenburg, Germany.
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Pinner AL, Mueller TM, Alganem K, McCullumsmith R, Meador-Woodruff JH. Protein expression of prenyltransferase subunits in postmortem schizophrenia dorsolateral prefrontal cortex. Transl Psychiatry 2020; 10:3. [PMID: 32066669 PMCID: PMC7026430 DOI: 10.1038/s41398-019-0610-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 09/09/2019] [Accepted: 10/03/2019] [Indexed: 12/22/2022] Open
Abstract
The pathophysiology of schizophrenia includes altered neurotransmission, dysregulated intracellular signaling pathway activity, and abnormal dendritic morphology that contribute to deficits of synaptic plasticity in the disorder. These processes all require dynamic protein-protein interactions at cell membranes. Lipid modifications target proteins to membranes by increasing substrate hydrophobicity by the addition of a fatty acid or isoprenyl moiety, and recent evidence suggests that dysregulated posttranslational lipid modifications may play a role in multiple neuropsychiatric disorders, including schizophrenia. Consistent with these emerging findings, we have recently reported decreased protein S-palmitoylation in schizophrenia. Protein prenylation is a lipid modification that occurs upstream of S-palmitoylation on many protein substrates, facilitating membrane localization and activity of key intracellular signaling proteins. Accordingly, we hypothesized that, in addition to palmitoylation, protein prenylation may be abnormal in schizophrenia. To test this, we assayed protein expression of the five prenyltransferase subunits (FNTA, FNTB, PGGT1B, RABGGTA, and RABGGTB) in postmortem dorsolateral prefrontal cortex from patients with schizophrenia and paired comparison subjects (n = 13 pairs). We found decreased levels of FNTA (14%), PGGT1B (13%), and RABGGTB (8%) in schizophrenia. To determine whether upstream or downstream factors may be driving these changes, we also assayed protein expression of the isoprenoid synthases FDPS and GGPS1 and prenylation-dependent processing enzymes RCE and ICMT. We found these upstream and downstream enzymes to have normal protein expression. To rule out effects from chronic antipsychotic treatment, we assayed FNTA, PGGT1B, and RABGGTB in the cortex from rats treated long-term with haloperidol decanoate and found no change in the expression of these proteins. Given the role prenylation plays in localization of key signaling proteins found at the synapse, these data offer a potential mechanism underlying abnormal protein-protein interactions and protein localization in schizophrenia.
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Affiliation(s)
- Anita L Pinner
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, AL, 35294-0021, USA.
| | - Toni M Mueller
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, AL, 35294-0021, USA
| | - Khaled Alganem
- Department of Neurosciences, University of Toledo, Toledo, OH, 43614-2598, USA
| | | | - James H Meador-Woodruff
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, AL, 35294-0021, USA
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Seliger JM, Cicek SS, Witt LT, Martin HJ, Maser E, Hintzpeter J. Selective Inhibition of Human AKR1B10 by n-Humulone, Adhumulone and Cohumulone Isolated from Humulus lupulus Extract. Molecules 2018; 23:E3041. [PMID: 30469331 PMCID: PMC6278539 DOI: 10.3390/molecules23113041] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 11/16/2018] [Accepted: 11/19/2018] [Indexed: 12/22/2022] Open
Abstract
Hop-derived compounds have been subjected to numerous biomedical studies investigating their impact on a wide range of pathologies. Isomerised bitter acids (isoadhumulone, isocohumulone and isohumulone) from hops, used in the brewing process of beer, are known to inhibit members of the aldo-keto-reductase superfamily. Aldo-keto-reductase 1B10 (AKR1B10) is upregulated in various types of cancer and has been reported to promote carcinogenesis. Inhibition of AKR1B10 appears to be an attractive means to specifically treat RAS-dependent malignancies. However, the closely related reductases AKR1A1 and AKR1B1, which fulfil important roles in the detoxification of endogenous and xenobiotic carbonyl compounds oftentimes crossreact with inhibitors designed to target AKR1B10. Accordingly, there is an ongoing search for selective AKR1B10 inhibitors that do not interact with endogeneous AKR1A1 and AKR1B1-driven detoxification systems. In this study, unisomerised α-acids (adhumulone, cohumulone and n-humulone) were separated and tested for their inhibitory potential on AKR1A1, AKR1B1 and AKR1B10. Also AKR1B10-mediated farnesal reduction was effectively inhibited by α-acid congeners with Ki-values ranging from 16.79 ± 1.33 µM (adhumulone) to 3.94 ± 0.33 µM (n-humulone). Overall, α-acids showed a strong inhibition with selectivity (115⁻137 fold) for AKR1B10. The results presented herein characterise hop-derived α-acids as a promising basis for the development of novel and selective AKR1B10-inhibitors.
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Affiliation(s)
- Jan Moritz Seliger
- Institute of Toxicology and Pharmacology for Natural Scientists, University Medical School Schleswig-Holstein, Campus Kiel, Brunswikerstr. 10, D-24105 Kiel, Germany.
| | - Serhat Sezai Cicek
- Department of Pharmaceutical Biology, Faculty of Mathematics and Natural Sciences, Christian-Albrechts-Universität zu Kiel, Gutenbergstraße 76, D-24118 Kiel, Germany.
| | - Lydia T Witt
- Department of Pharmaceutical Chemistry, Faculty of Mathematics and Natural Sciences, Christian-Albrechts-Universität zu Kiel, Gutenbergstraße 76, D-24118 Kiel, Germany.
| | - Hans-Jörg Martin
- Institute of Toxicology and Pharmacology for Natural Scientists, University Medical School Schleswig-Holstein, Campus Kiel, Brunswikerstr. 10, D-24105 Kiel, Germany.
| | - Edmund Maser
- Institute of Toxicology and Pharmacology for Natural Scientists, University Medical School Schleswig-Holstein, Campus Kiel, Brunswikerstr. 10, D-24105 Kiel, Germany.
| | - Jan Hintzpeter
- Institute of Toxicology and Pharmacology for Natural Scientists, University Medical School Schleswig-Holstein, Campus Kiel, Brunswikerstr. 10, D-24105 Kiel, Germany.
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Blanden MJ, Suazo KF, Hildebrandt ER, Hardgrove DS, Patel M, Saunders WP, Distefano MD, Schmidt WK, Hougland JL. Efficient farnesylation of an extended C-terminal C( x) 3X sequence motif expands the scope of the prenylated proteome. J Biol Chem 2017; 293:2770-2785. [PMID: 29282289 DOI: 10.1074/jbc.m117.805770] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Revised: 12/24/2017] [Indexed: 12/25/2022] Open
Abstract
Protein prenylation is a post-translational modification that has been most commonly associated with enabling protein trafficking to and interaction with cellular membranes. In this process, an isoprenoid group is attached to a cysteine near the C terminus of a substrate protein by protein farnesyltransferase (FTase) or protein geranylgeranyltransferase type I or II (GGTase-I and GGTase-II). FTase and GGTase-I have long been proposed to specifically recognize a four-amino acid CAAX C-terminal sequence within their substrates. Surprisingly, genetic screening reveals that yeast FTase can modify sequences longer than the canonical CAAX sequence, specifically C(x)3X sequences with four amino acids downstream of the cysteine. Biochemical and cell-based studies using both peptide and protein substrates reveal that mammalian FTase orthologs can also prenylate C(x)3X sequences. As the search to identify physiologically relevant C(x)3X proteins begins, this new prenylation motif nearly doubles the number of proteins within the yeast and human proteomes that can be explored as potential FTase substrates. This work expands our understanding of prenylation's impact within the proteome, establishes the biologically relevant reactivity possible with this new motif, and opens new frontiers in determining the impact of non-canonically prenylated proteins on cell function.
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Affiliation(s)
- Melanie J Blanden
- Department of Chemistry, Syracuse University, Syracuse, New York 13244
| | - Kiall F Suazo
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455
| | - Emily R Hildebrandt
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602
| | - Daniel S Hardgrove
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602
| | - Meet Patel
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602
| | - William P Saunders
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602
| | - Mark D Distefano
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455
| | - Walter K Schmidt
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602
| | - James L Hougland
- Department of Chemistry, Syracuse University, Syracuse, New York 13244.
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7
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Cho E, Park M. Palmitoylation in Alzheimers disease and other neurodegenerative diseases. Pharmacol Res 2016; 111:133-151. [DOI: 10.1016/j.phrs.2016.06.008] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 06/07/2016] [Accepted: 06/08/2016] [Indexed: 12/13/2022]
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Abstract
Protein palmitoylation, by modulating the dynamic interaction between protein and cellular membrane, is involved in a wide range of biological processes, including protein trafficking, sorting, sub-membrane partitioning, protein-protein interaction and cell signaling. To explore the role of protein palmitoylation in adipocytes, we have performed proteomic analysis of palmitoylated proteins in adipose tissue and 3T3-L1 adipocytes and identified more than 800 putative palmitoylated proteins. These include various transporters, enzymes required for lipid and glucose metabolism, regulators of protein trafficking and signaling molecules. Of note, key proteins involved in membrane translocation of the glucose-transporter Glut4 including IRAP, Munc18c, AS160 and Glut4, and signaling proteins in the JAK-STAT pathway including JAK1 and 2, STAT1, 3 and 5A and SHP2 in JAK-STAT, were palmitoylated in cultured adipocytes and primary adipose tissue. Further characterization showed that palmitoylation of Glut4 and IRAP was altered in obesity, and palmitoylation of JAK1 played a regulatory role in JAK1 intracellular localization. Overall, our studies provide evidence to suggest a novel and potentially regulatory role for protein palmitoylation in adipocyte function.
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9
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Flynn SC, Lindgren DE, Hougland JL. Quantitative determination of cellular farnesyltransferase activity: towards defining the minimum substrate reactivity for biologically relevant protein farnesylation. Chembiochem 2014; 15:2205-10. [PMID: 25182009 DOI: 10.1002/cbic.201402239] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Indexed: 11/10/2022]
Abstract
Prenylation is a post-translational modification wherein an isoprenoid group is attached to a protein substrate by a protein prenyltransferase. Hundreds of peptide sequences are in vitro substrates for protein farnesyltransferase (FTase), but it remains unknown which of these sequences can successfully compete for in vivo prenylation. Translating in vitro studies to predict in vivo protein farnesylation requires determining the minimum reactivity needed for modification by FTase within the cell. Towards this goal, we developed a reporter protein series spanning several orders of magnitude in FTase reactivity as a calibrated sensor for endogenous FTase activity. Our approach provides a minimally invasive method to monitor changes in cellular FTase activity in response to environmental or genetic factors. Determining the reactivity "threshold" for in vivo prenylation will help define the prenylated proteome and identify prenylation-dependent pathways for therapeutic targeting.
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Affiliation(s)
- Susan C Flynn
- Syracuse University Department of Chemistry, 1-014 Center for Science and Technology, Syracuse, NY 13244-4100 (USA)
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Gangopadhyay SA, Losito EL, Hougland JL. Targeted reengineering of protein geranylgeranyltransferase type I selectivity functionally implicates active-site residues in protein-substrate recognition. Biochemistry 2014; 53:434-46. [PMID: 24344934 DOI: 10.1021/bi4011732] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Posttranslational modifications are vital for the function of many proteins. Prenylation is one such modification, wherein protein geranylgeranyltransferase type I (GGTase-I) or protein farnesyltransferase (FTase) modify proteins by attaching a 20- or 15-carbon isoprenoid group, respectively, to a cysteine residue near the C-terminus of a target protein. These enzymes require a C-terminal Ca1a2X sequence on their substrates, with the a1, a2, and X residues serving as substrate-recognition elements for FTase and/or GGTase-I. While crystallographic structures of rat GGTase-I show a tightly packed and hydrophobic a2 residue binding pocket, consistent with a preference for moderately sized a2 residues in GGTase-I substrates, the functional impact of enzyme-substrate contacts within this active site remains to be determined. Using site-directed mutagenesis and peptide substrate structure-activity studies, we have identified specific active-site residues within rat GGTase-I involved in substrate recognition and developed novel GGTase-I variants with expanded/altered substrate selectivity. The ability to drastically alter GGTase-I selectivity mirrors similar behavior observed in FTase but employs mutation of a distinct set of structurally homologous active-site residues. Our work demonstrates that tunable selectivity may be a general phenomenon among multispecific enzymes involved in posttranslational modification and raises the possibility of variable substrate selectivity among GGTase-I orthologues from different organisms. Furthermore, the GGTase-I variants developed herein can serve as tools for studying GGTase-I substrate selectivity and the effects of prenylation pathway modifications on specific proteins.
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Hougland JL, Gangopadhyay SA, Fierke CA. Expansion of protein farnesyltransferase specificity using "tunable" active site interactions: development of bioengineered prenylation pathways. J Biol Chem 2012; 287:38090-100. [PMID: 22992747 DOI: 10.1074/jbc.m112.404954] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Post-translational modifications play essential roles in regulating protein structure and function. Protein farnesyltransferase (FTase) catalyzes the biologically relevant lipidation of up to several hundred cellular proteins. Site-directed mutagenesis of FTase coupled with peptide selectivity measurements demonstrates that molecular recognition is determined by a combination of multiple interactions. Targeted randomization of these interactions yields FTase variants with altered and, in some cases, bio-orthogonal selectivity. We demonstrate that FTase specificity can be "tuned" using a small number of active site contacts that play essential roles in discriminating against non-substrates in the wild-type enzyme. This tunable selectivity extends in vivo, with FTase variants enabling the creation of bioengineered parallel prenylation pathways with altered substrate selectivity within a cell. Engineered FTase variants provide a novel avenue for probing both the selectivity of prenylation pathway enzymes and the effects of prenylation pathway modifications on the cellular function of a protein.
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Affiliation(s)
- James L Hougland
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA.
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12
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Ou-yang Z, Wang P, Huang Y, Huang X, Wan Q, Zhou S, Wei J, Zhou Y, Qin Q. Selection and identification of Singapore grouper iridovirus vaccine candidate antigens using bioinformatics and DNA vaccination. Vet Immunol Immunopathol 2012; 149:38-45. [DOI: 10.1016/j.vetimm.2012.05.021] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Revised: 05/15/2012] [Accepted: 05/26/2012] [Indexed: 11/29/2022]
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Chung YT, Matkowskyj KA, Li H, Bai H, Zhang W, Tsao MS, Liao J, Yang GY. Overexpression and oncogenic function of aldo-keto reductase family 1B10 (AKR1B10) in pancreatic carcinoma. Mod Pathol 2012; 25:758-66. [PMID: 22222635 PMCID: PMC3323665 DOI: 10.1038/modpathol.2011.191] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Aldo-keto reductase family 1B10 (AKR1B10) exhibits more restricted lipid substrate specificity (including farnesal, geranylgeranial, retinal and carbonyls), and metabolizing these lipid substrates has a crucial role in promoting carcinogenesis. Overexpression of AKR1B10 has been identified in smoking-related carcinomas such as lung cancer. As development of pancreatic cancer is firmly linked to smoking, the aim of the present study was to examine the expression and oncogenic role of AKR1B10 in pancreatic adenocarcinoma. AKR1B10 expression was analyzed in 50 paraffin-embedded clinical pancreatic cancer samples using immunohistochemistry. Oncogenic function of AKR1B10 was examined in pancreatic carcinoma cells in vitro using western blotting and siRNA approaches, mainly on cell apoptosis and protein prenylation including KRAS protein and its downstream signals. Immunohistochemistry analysis revealed that AKR1B10 overexpressed in 70% (35/50) of pancreatic adenocarcinomas and majority of pancreatic intraepithelial neoplasia, but not in adjacent morphologically normal pancreatic tissue. Compared with a normal pancreatic ductal epithelial cell (HPDE6E7), all of the six cultured pancreatic adenocarcinoma cell lines had an overexpression of AKR1B10 using immunoblotting, which correlated with increase of enzyme activity. siRNA-mediated silencing of AKR1B10 expression in pancreatic cancer cells resulted in (1) increased cell apoptosis, (2) increased non-farnesyled HDJ2 protein and (3) decreased membrane-bound prenylated KRAS protein and its downstream signaling molecules including phosphorylated ERK and MEK and membrane-bound E-cadherin. Our findings provide first time evidence that AKR1B10 is a unique enzyme involved in pancreatic carcinogenesis possibly via modulation of cell apoptosis and protein prenylation.
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Affiliation(s)
- Yeon Tae Chung
- Department of Pathology, Northwestern University, Feinberg School of Medicine; Chicago, IL 60611, USA
| | - Kristina A. Matkowskyj
- Department of Pathology, Northwestern University, Feinberg School of Medicine; Chicago, IL 60611, USA
| | - Haonan Li
- Department of Pathology, Northwestern University, Feinberg School of Medicine; Chicago, IL 60611, USA
| | - Han Bai
- Department of Pathology, Northwestern University, Feinberg School of Medicine; Chicago, IL 60611, USA
| | - Wanying Zhang
- Department of Pathology, Northwestern University, Feinberg School of Medicine; Chicago, IL 60611, USA
| | - Ming-Sound Tsao
- Ontario Cancer Institute, Princess Margaret Hospital; Toronto, Ontario, Canada
| | - Jie Liao
- Department of Pathology, Northwestern University, Feinberg School of Medicine; Chicago, IL 60611, USA
| | - Guang-Yu Yang
- Department of Pathology, Northwestern University, Feinberg School of Medicine; Chicago, IL 60611, USA.,Corresponding Author: Guang-Yu Yang, MD, PhD, Department of Pathology, Northwestern University, Feinberg School of Medicine, 303 E. Chicago Ave, Ward 6-118, Chicago, IL 60611, Tel: (312) 503-0645, Fax: (312)503-0647,
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14
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Liao J, Chung YT, Yang AL, Zhang M, Li H, Zhang W, Yan L, Yang GY. Atorvastatin inhibits pancreatic carcinogenesis and increases survival in LSL-KrasG12D-LSL-Trp53R172H-Pdx1-Cre mice. Mol Carcinog 2012; 52:739-50. [PMID: 22549877 DOI: 10.1002/mc.21916] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Revised: 03/13/2012] [Accepted: 03/21/2012] [Indexed: 12/13/2022]
Abstract
There are several studies supporting the role of HMG-CoA reductase inhibitors such as atorvastatin against carcinogenesis, in which inhibiting the generation of prenyl intermediates involved in protein prenylation plays the crucial role. Mutation of Kras gene is the most common genetic alteration in pancreatic cancer and the Ras protein requires prenylation for its membrane localization and activity. In the present study, the effectiveness of atorvastatin against pancreatic carcinogenesis and its effect on protein prenylation were determined using the LSL-KrasG12D-LSL-Trp53R172H-Pdx1-Cre mouse model (called Pankras/p53 mice). Five-week-old Pankras/p53 mice were fed either an AIN93M diet or a diet supplemented with 100 ppm atorvastatin. Kaplan-Meier survival analysis with Log-Rank test revealed a significant increase in survival in mice fed 100 ppm atorvastatin (171.9 ± 6.2 d) compared to the control mice (144.9 ± 8.4 d, P < 0.05). Histologic and immunohistochemical analysis showed that atorvastatin treatment resulted in a significant reduction in tumor volume and Ki-67-labeled cell proliferation. Mechanistic studies on primary pancreatic tumors and the cultured murine pancreatic carcinoma cells revealed that atorvastatin inhibited prenylation in several key proteins, including Kras protein and its activities, and similar effect was observed in pancreatic carcinoma cells treated with farnesyltransferase inhibitor R115777. Microarray assay on the global gene expression profile demonstrated that a total of 132 genes were significantly modulated by atorvastatin; and Waf1p21, cyp51A1, and soluble epoxide hydrolase were crucial atorvastatin-targeted genes which involve in inflammation and carcinogenesis. This study indicates that atorvastatin has the potential to serve as a chemopreventive agent against pancreatic carcinogenesis.
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Affiliation(s)
- Jie Liao
- Department of Pathology, Northwestern University, Feinberg School of Medicine, Chicago, IL 60611, USA
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London N, Lamphear CL, Hougland JL, Fierke CA, Schueler-Furman O. Identification of a novel class of farnesylation targets by structure-based modeling of binding specificity. PLoS Comput Biol 2011; 7:e1002170. [PMID: 21998565 PMCID: PMC3188499 DOI: 10.1371/journal.pcbi.1002170] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Accepted: 07/01/2011] [Indexed: 11/19/2022] Open
Abstract
Farnesylation is an important post-translational modification catalyzed by farnesyltransferase (FTase). Until recently it was believed that a C-terminal CaaX motif is required for farnesylation, but recent experiments have revealed larger substrate diversity. In this study, we propose a general structural modeling scheme to account for peptide binding specificity and recapitulate the experimentally derived selectivity profile of FTase in vitro. In addition to highly accurate recovery of known FTase targets, we also identify a range of novel potential targets in the human genome, including a new substrate class with an acidic C-terminal residue (CxxD/E). In vitro experiments verified farnesylation of 26/29 tested peptides, including both novel human targets, as well as peptides predicted to tightly bind FTase. This study extends the putative range of biological farnesylation substrates. Moreover, it suggests that the ability of a peptide to bind FTase is a main determinant for the farnesylation reaction. Finally, simple adaptation of our approach can contribute to more accurate and complete elucidation of peptide-mediated interactions and modifications in the cell.
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Affiliation(s)
- Nir London
- Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, Hadassah Medical School, The Hebrew University, Jerusalem, Israel
| | - Corissa L. Lamphear
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan, United States of America
| | - James L. Hougland
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Carol A. Fierke
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan, United States of America
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Ora Schueler-Furman
- Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, Hadassah Medical School, The Hebrew University, Jerusalem, Israel
- * E-mail:
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16
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Kwon MJ, Arentshorst M, Roos ED, van den Hondel CAMJJ, Meyer V, Ram AFJ. Functional characterization of Rho GTPases in Aspergillus niger uncovers conserved and diverged roles of Rho proteins within filamentous fungi. Mol Microbiol 2011; 79:1151-67. [DOI: 10.1111/j.1365-2958.2010.07524.x] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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17
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Global Identification of Protein Prenyltransferase Substrates. ACTA ACUST UNITED AC 2011. [DOI: 10.1016/b978-0-12-381339-8.00012-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/06/2023]
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18
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19
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Hougland JL, Lamphear CL, Scott SA, Gibbs RA, Fierke CA. Context-dependent substrate recognition by protein farnesyltransferase. Biochemistry 2010; 48:1691-701. [PMID: 19199818 DOI: 10.1021/bi801710g] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Prenylation is a posttranslational modification whereby C-terminal lipidation leads to protein localization to membranes. A C-terminal "Ca(1)a(2)X" sequence has been proposed as the recognition motif for two prenylation enzymes, protein farnesyltransferase (FTase) and protein geranylgeranyltransferase type I. To define the parameters involved in recognition of the a(2) residue, we performed structure-activity analysis which indicates that FTase discriminates between peptide substrates based on both the hydrophobicity and steric volume of the side chain at the a(2) position. For nonpolar side chains, the dependence of the reactivity on side chain volume at this position forms a pyramidal pattern with a maximal activity near the steric volume of valine. This discrimination occurs at a step in the kinetic mechanism that is at or before the farnesylation step. Furthermore, a(2) selectivity is also affected by the identity of the adjacent X residue, leading to context-dependent substrate recognition. Context-dependent a(2) selectivity suggests that FTase recognizes the sequence downstream of the conserved cysteine as a set of two or three cooperative, interconnected recognition elements as opposed to three independent amino acids. These findings expand the pool of proposed FTase substrates in cells. A better understanding of the molecular recognition of substrates performed by FTase will aid in both designing new FTase inhibitors as therapeutic agents and characterizing proteins involved in prenylation-dependent cellular pathways.
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Affiliation(s)
- James L Hougland
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA
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20
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Hougland JL, Hicks KA, Hartman HL, Kelly RA, Watt TJ, Fierke CA. Identification of novel peptide substrates for protein farnesyltransferase reveals two substrate classes with distinct sequence selectivities. J Mol Biol 2010; 395:176-90. [PMID: 19878682 PMCID: PMC2916699 DOI: 10.1016/j.jmb.2009.10.038] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2009] [Revised: 10/15/2009] [Accepted: 10/16/2009] [Indexed: 10/20/2022]
Abstract
Prenylation is a posttranslational modification essential for the proper localization and function of many proteins. Farnesylation, the attachment of a 15-carbon farnesyl group near the C-terminus of protein substrates, is catalyzed by protein farnesyltransferase (FTase). Farnesylation has received significant interest as a target for pharmaceutical development, and farnesyltransferase inhibitors are in clinical trials as cancer therapeutics. However, as the total complement of prenylated proteins is unknown, the FTase substrates responsible for farnesyltransferase inhibitor efficacy are not yet understood. Identifying novel prenylated proteins within the human proteome constitutes an important step towards understanding prenylation-dependent cellular processes. Based on sequence preferences for FTase derived from analysis of known farnesylated proteins, we selected and screened a library of small peptides representing the C-termini of 213 human proteins for activity with FTase. We identified 77 novel FTase substrates that exhibit multiple-turnover (MTO) reactivity within this library; our library also contained 85 peptides that can be farnesylated by FTase only under single-turnover (STO) conditions. Based on these results, a second library was designed that yielded an additional 29 novel MTO FTase substrates and 45 STO substrates. The two classes of substrates exhibit different specificity requirements. Efficient MTO reactivity correlates with the presence of a nonpolar amino acid at the a(2) position and a Phe, Met, or Gln at the terminal X residue, consistent with the proposed Ca(1)a(2)X sequence model. In contrast, the sequences of the STO substrates vary significantly more at both the a(2) and the X residues and are not well described by current farnesylation algorithms. These results improve the definition of prenyltransferase substrate specificity, test the efficacy of substrate algorithms, and provide valuable information about therapeutic targets. Finally, these data illuminate the potential for in vivo regulation of prenylation through modulation of STO versus MTO peptide reactivity with FTase.
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Affiliation(s)
- James L. Hougland
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109
| | - Katherine A. Hicks
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109
| | - Heather L. Hartman
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109
| | - Rebekah A. Kelly
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109
| | - Terry J. Watt
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109
| | - Carol A. Fierke
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109
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21
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22
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Bailey LK, Campbell LJ, Evetts KA, Littlefield K, Rajendra E, Nietlispach D, Owen D, Mott HR. The structure of binder of Arl2 (BART) reveals a novel G protein binding domain: implications for function. J Biol Chem 2008; 284:992-9. [PMID: 18981177 DOI: 10.1074/jbc.m806167200] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The ADP-ribosylation factor-like (Arl) family of small G proteins are involved in the regulation of diverse cellular processes. Arl2 does not appear to be membrane localized and has been implicated as a regulator of microtubule dynamics. The downstream effector for Arl2, Binder of Arl 2 (BART) has no known function but, together with Arl2, can enter mitochondria and bind the adenine nucleotide transporter. We have solved the solution structure of BART and show that it forms a novel fold composed of six alpha-helices that form three interlocking "L" shapes. Analysis of the backbone dynamics reveals that the protein is highly anisotropic and that the loops between the central helices are dynamic. The regions involved in the binding of Arl2 were mapped onto the surface of BART and are found to localize to these loop regions. BART has faces of differing charge and structural elements, which may explain how it can interact with other proteins.
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Affiliation(s)
- Laura K Bailey
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, United Kingdom
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23
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Reviews in Molecular Biology and Biotechnology: Transmembrane Signaling by G Protein-Coupled Receptors. Mol Biotechnol 2008; 39:239-64. [DOI: 10.1007/s12033-008-9031-1] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2008] [Accepted: 01/07/2008] [Indexed: 01/14/2023]
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24
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Ye Y, Fujii M, Hirata A, Kawamukai M, Shimoda C, Nakamura T. Geranylgeranyl diphosphate synthase in fission yeast is a heteromer of farnesyl diphosphate synthase (FPS), Fps1, and an FPS-like protein, Spo9, essential for sporulation. Mol Biol Cell 2007; 18:3568-81. [PMID: 17596513 PMCID: PMC1951748 DOI: 10.1091/mbc.e07-02-0112] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Both farnesyl diphosphate synthase (FPS) and geranylgeranyl diphosphate synthase (GGPS) are key enzymes in the synthesis of various isoprenoid-containing compounds and proteins. Here, we describe two novel Schizosaccharomyces pombe genes, fps1(+) and spo9(+), whose products are similar to FPS in primary structure, but whose functions differ from one another. Fps1 is essential for vegetative growth, whereas, a spo9 null mutant exhibits temperature-sensitive growth. Expression of fps1(+), but not spo9(+), suppresses the lethality of a Saccharomyces cerevisiae FPS-deficient mutant and also restores ubiquinone synthesis in an Escherichia coli ispA mutant, which lacks FPS activity, indicating that S. pombe Fps1 in fact functions as an FPS. In contrast to a typical FPS gene, no apparent GGPS homologues have been found in the S. pombe genome. Interestingly, although neither fps1(+) nor spo9(+) expression alone in E. coli confers clear GGPS activity, coexpression of both genes induces such activity. Moreover, the GGPS activity is significantly reduced in the spo9 mutant. In addition, the spo9 mutation perturbs the membrane association of a geranylgeranylated protein, but not that of a farnesylated protein. Yeast two-hybrid and coimmunoprecipitation analyses indicate that Fps1 and Spo9 physically interact. Thus, neither Fps1 nor Spo9 alone functions as a GGPS, but the two proteins together form a complex with GGPS activity. Because spo9 was originally identified as a sporulation-deficient mutant, we show here that expansion of the forespore membrane is severely inhibited in spo9Delta cells. Electron microscopy revealed significant accumulation membrane vesicles in spo9Delta cells. We suggest that lack of GGPS activity in a spo9 mutant results in impaired protein prenylation in certain proteins responsible for secretory function, thereby inhibiting forespore membrane formation.
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Affiliation(s)
- Yanfang Ye
- *Department of Biology, Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka 558-8585, Japan
| | - Makoto Fujii
- Department of Applied Bioscience and Biotechnology, Faculty of Life and Environmental Science, Shimane University, Matsue 690-8504, Japan
| | - Aiko Hirata
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Chiba 277-8562, Japan; and
| | - Makoto Kawamukai
- Department of Applied Bioscience and Biotechnology, Faculty of Life and Environmental Science, Shimane University, Matsue 690-8504, Japan
| | - Chikashi Shimoda
- *Department of Biology, Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka 558-8585, Japan
| | - Taro Nakamura
- *Department of Biology, Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka 558-8585, Japan
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25
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Suzuki T, Ito M, Ezure T, Shikata M, Ando E, Utsumi T, Tsunasawa S, Nishimura O. Protein prenylation in an insect cell-free protein synthesis system and identification of products by mass spectrometry. Proteomics 2007; 7:1942-50. [PMID: 17514686 DOI: 10.1002/pmic.200700237] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
To evaluate the ability of an insect cell-free protein synthesis system to carry out proper protein prenylation, several CAIX (X indicates any C-terminal amino acid) sequences were introduced into the C-terminus of truncated human gelsolin (tGelsolin). Tryptic digests of these mutant proteins were analyzed by MALDI-TOF MS and MALDI-quadrupole-IT-TOF MS. The results indicated that the insect cell-free protein synthesis system possesses both farnesyltransferase (FTase) and geranylgeranyltransferase (GGTase) I, as is the case of the rabbit reticulocyte lysate system. The C-terminal amino acid sequence requirements for protein prenylation in this system showed high similarity to those observed in rat prenyltransferases. In the case of rhoC, which is a natural geranylgeranylated protein, it was found that it could serve as a substrate for both prenyltransferases in the presence of either farnesyl or geranylgeranyl pyrophosphate, whereas geranylgeranylation was only observed when both prenyl pyrophosphates were added to the in vitro translation reaction mixture. Thus, a combination of the cell-free protein synthesis system with MS is an effective strategy to analyze protein prenylation.
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Affiliation(s)
- Takashi Suzuki
- Life Science Laboratory, Analytical and Measuring Instruments Division, Shimadzu Corporation, Kyoto, Japan.
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26
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Edwards CM, Mueller G, Roelofs AJ, Chantry A, Perry M, Russell RGG, Van Camp B, Guyon-Gellin Y, Niesor EJ, Bentzen CL, Vanderkerken K, Croucher PI. Apomine, an inhibitor of HMG-CoA-reductase, promotes apoptosis of myeloma cells in vitro and is associated with a modulation of myeloma in vivo. Int J Cancer 2007; 120:1657-63. [PMID: 17230522 DOI: 10.1002/ijc.22478] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Apomine, a novel 1,1 bisphosphonate ester, increases the rate of degradation of HMG-CoA reductase, inhibiting the mevalonate pathway and thereby blocking cholesterol biosynthesis. We have investigated whether Apomine can induce myeloma cell apoptosis in vitro and modulate myeloma disease in vivo. Apomine induced a dose-dependent increase in apoptosis in NCI H929, RPMI 8226 and JJN-3 human myeloma cells. Apomine, unlike the bisphosphonate, alendronate, had no measurable effect on osteoclastic bone resorption in vitro. To investigate the effect of Apomine in vivo, 5T2MM murine myeloma cells were injected into C57BL/KaLwRij mice. After 8 weeks all animals had a serum paraprotein and were treated with Apomine (200 mg/kg), or vehicle, for 4 weeks. Animals injected with 5T2MM cells and treated with vehicle developed osteolytic bone lesions, reduced cancellous bone area, decreased bone mineral density (BMD) and increased osteoclast number. Apomine caused a decrease in serum paraprotein and a decrease in tumor burden. Apomine inhibited the development of osteolytic lesions and prevented the tumor-induced decreases in BMD. Apomine had no effect on osteoclast number in contrast to what had been seen previously with the bisphosphonate, zoledronic acid, suggesting that these are direct effects of Apomine on myeloma cells. This demonstrates that Apomine is able to promote myeloma cell apoptosis in vitro and inhibit the development of multiple myeloma and lytic bone disease in vivo. The use of bisphosphonate esters such as Apomine represents a novel therapeutic approach in the treatment of myeloma and, indirectly, the associated bone disease.
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Affiliation(s)
- Claire M Edwards
- Institute of Musculoskeletal Sciences and the Nuffield Department of Orthopaedic Surgery, University of Oxford, Nuffield Orthopaedic Center, Oxford, United Kingdom
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27
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Abstract
Although oncogenes and their transformation mechanisms have been known for 30 years, we are just now using our understanding of protein function to abrogate the activity of these genes to block cancer growth. The advent of specific small-molecule inhibitors has been a tremendous step in the fight against cancer and their main targets are the cellular counterparts of viral oncogenes. The best-known example of a molecular therapeutic is Gleevec (imatinib). In the early 1990s, IFN-alpha treatment produced a sustained cytologic response in approximately 33% of chronic myelogenous leukemia patients. Today, with Gleevec targeting the kinase activity of the proto-oncogene abl, the hematologic response rate in chronic myelogenous leukemia patients is 95% with 89% progression-free survival at 18 months. There are still drawbacks to the new therapies, such as drug resistance after a period of treatment, but the drawbacks are being studied experimentally. New drugs and combination therapies are being designed that will bypass the resistance mechanisms.
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Affiliation(s)
- Kathleen M Diehl
- Department of Urology, University of Michigan, 1500 East Medical Center Drive, Ann Arbor, MI 48109-0940, USA
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28
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Sprang SR, Chen Z, Du X. Structural basis of effector regulation and signal termination in heterotrimeric Galpha proteins. ADVANCES IN PROTEIN CHEMISTRY 2007; 74:1-65. [PMID: 17854654 DOI: 10.1016/s0065-3233(07)74001-9] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
This chapter addresses, from a molecular structural perspective gained from examination of x-ray crystallographic and biochemical data, the mechanisms by which GTP-bound Galpha subunits of heterotrimeric G proteins recognize and regulate effectors. The mechanism of GTP hydrolysis by Galpha and rate acceleration by GAPs are also considered. The effector recognition site in all Galpha homologues is formed almost entirely of the residues extending from the C-terminal half of alpha2 (Switch II) together with the alpha3 helix and its junction with the beta5 strand. Effector binding does not induce substantial changes in the structure of Galpha*GTP. Effectors are structurally diverse. Different effectors may recognize distinct subsets of effector-binding residues of the same Galpha protein. Specificity may also be conferred by differences in the main chain conformation of effector-binding regions of Galpha subunits. Several Galpha regulatory mechanisms are operative. In the regulation of GMP phospodiesterase, Galphat sequesters an inhibitory subunit. Galphas is an allosteric activator and inhibitor of adenylyl cyclase, and Galphai is an allosteric inhibitor. Galphaq does not appear to regulate GRK, but is rather sequestered by it. GTP hydrolysis terminates the signaling state of Galpha. The binding energy of GTP that is used to stabilize the Galpha:effector complex is dissipated in this reaction. Chemical steps of GTP hydrolysis, specifically, formation of a dissociative transition state, is rate limiting in Ras, a model G protein GTPase, even in the presence of a GAP; however, the energy of enzyme reorganization to produce a catalytically active conformation appears to be substantial. It is possible that the collapse of the switch regions, associated with Galpha deactivation, also encounters a kinetic barrier, and is coupled to product (Pi) release or an event preceding formation of the GDP*Pi complex. Evidence for a catalytic intermediate, possibly metaphosphate, is discussed. Galpha GAPs, whether exogenous proteins or effector-linked domains, bind to a discrete locus of Galpha that is composed of Switch I and the N-terminus of Switch II. This site is immediately adjacent to, but does not substantially overlap, the Galpha effector binding site. Interactions of effectors and exogenous GAPs with Galpha proteins can be synergistic or antagonistic, mediated by allosteric interactions among the three molecules. Unlike GAPs for small GTPases, Galpha GAPs supply no catalytic residues, but rather appear to reduce the activation energy for catalytic activation of the Galpha catalytic site.
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Affiliation(s)
- Stephen R Sprang
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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29
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Palmer DA, Thompson JK, Li L, Prat A, Wang P. Gib2, a novel Gbeta-like/RACK1 homolog, functions as a Gbeta subunit in cAMP signaling and is essential in Cryptococcus neoformans. J Biol Chem 2006; 281:32596-605. [PMID: 16950773 DOI: 10.1074/jbc.m602768200] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Canonical G proteins are heterotrimeric, consisting of alpha, beta, and gamma subunits. Despite multiple Galpha subunits functioning in fungi, only a single Gbeta subunit per species has been identified, suggesting that non-conventional G protein signaling exists in this diverse group of eukaryotic organisms. Using the Galpha subunit Gpa1 that functions in cAMP signaling as bait in a two-hybrid screen, we have identified a novel Gbeta-like/RACK1 protein homolog, Gib2, from the human pathogenic fungus Cryptococcus neoformans. Gib2 contains a seven WD-40 repeat motif and is predicted to form a seven-bladed beta propeller structure characteristic of beta transducins. Gib2 is also shown to interact, respectively, with two Ggamma subunit homologs, Gpg1 and Gpg2, similar to the conventional Gbeta subunit Gpb1. In contrast to Gpb1 whose overexpression promotes mating response, overproduction of Gib2 suppresses defects of gpa1 mutation in both melanization and capsule formation, the phenotypes regulated by cAMP signaling and associated with virulence. Furthermore, depletion of Gib2 by antisense suppression results in a severe growth defect, suggesting that Gib2 is essential. Finally, Gib2 is shown to also physically interact with a downstream target of Gpa1-cAMP signaling, Smg1, and the protein kinase C homolog Pkc1, indicating that Gib2 is also a multifunctional RACK1-like protein.
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Affiliation(s)
- Daniel A Palmer
- Research Institute for Children, Department of Pediatrics, Louisiana State University Health Sciences Center, 200 Henry Clay Avenue, New Orleans, LA 70118, USA
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30
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Zambruni A, Trevisani F, Caraceni P, Bernardi M. Cardiac electrophysiological abnormalities in patients with cirrhosis. J Hepatol 2006; 44:994-1002. [PMID: 16510203 DOI: 10.1016/j.jhep.2005.10.034] [Citation(s) in RCA: 123] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2005] [Revised: 09/08/2005] [Accepted: 10/11/2005] [Indexed: 01/01/2023]
Affiliation(s)
- Andrea Zambruni
- Dipartimento di Medicina Interna, Cardioangiologia ed Epatologia, Alma Mater Studiorum-Università di Bologna, Semeiotica Medica Policlinico S. Orsola-Malpighi Via Albertoni, 15 40138 Bologna, Italy
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31
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Kiss AL, Turi A, Müllner N, Kovács E, Botos E, Greger A. Oestrogen-mediated tyrosine phosphorylation of caveolin-1 and its effect on the oestrogen receptor localisation: an in vivo study. Mol Cell Endocrinol 2005; 245:128-37. [PMID: 16368181 DOI: 10.1016/j.mce.2005.11.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2005] [Revised: 11/08/2005] [Accepted: 11/10/2005] [Indexed: 01/23/2023]
Abstract
Recently, it has been shown that 17beta estradiol (E2) induces a rapid and transient activation of the Src ERK phosphorylation cascade: a clear indication that the alpha oestrogen receptor (ERalpha) is able to associate with the plasma membrane. Increasing evidence suggests that caveolae, which are caveolin-1 containing, highly hydrophobic membrane domains, play an important role in E2 induced signal transduction. Caveolae can accumulate signalling molecules preferentially; thus, they may have a regulatory role in signalling processes. Results from previous experiments have shown that E2 treatment decreased the number of surface connected caveolae significantly in uterine smooth muscle cells and also downregulated the expression of caveolin-1. In addition to providing further evidence that ERalpha interacts with caveolin/caveolae in uterine smooth muscle cells, this study also shows that the interaction between caveolin-1 and ERalpha is actually facilitated by E2. One of the signal transduction components found to accumulate in caveolae is Src kinase in an amount that increases simultaneously with increases in the amount of ERalpha. Upon E2 treatment, Src kinase is tyrosine phosphorylated, which, in turn, stimulates Src kinase to phosphorylate caveolin-1. Phosphorylation of caveolin-1 can drive caveolae to pinch off from the plasma membrane, thereby decreasing the amount of plasma membrane-associated caveolin-1. This loss of caveolin/caveolae activates the signal cascade that triggers cell proliferation.
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Affiliation(s)
- Anna L Kiss
- Department of Human Morphology and Developmental Biology, Semmelweis University Budapest, H-1450 Budapest, Tuzoltó u. 58, Hungary.
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32
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Huang Y, Sirkowski EE, Stickney JT, Scherer SS. Prenylation-defective human connexin32 mutants are normally localized and function equivalently to wild-type connexin32 in myelinating Schwann cells. J Neurosci 2005; 25:7111-20. [PMID: 16079393 PMCID: PMC6725241 DOI: 10.1523/jneurosci.1319-05.2005] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2005] [Revised: 06/17/2005] [Accepted: 06/18/2005] [Indexed: 12/18/2022] Open
Abstract
Mutations in GJB1, the gene encoding the gap junction protein connexin32 (Cx32), cause the X-linked form of Charcot-Marie-Tooth disease, an inherited demyelinating neuropathy. The C terminus of human Cx32 contains a putative prenylation motif that is conserved in Cx32 orthologs. Using [3H]mevalonolactone ([3H]MVA) incorporation, we demonstrated that wild-type human connexin32 can be prenylated in COS7 cells, in contrast to disease-associated mutations that are predicted to disrupt the prenylation motif. We generated transgenic mice that express these mutants in myelinating Schwann cells. Male mice expressing a transgene were crossed with female Gjb1-null mice; the male offspring were all Gjb1-null, and one-half were transgene positive; in these mice, all Cx32 was derived from expression of the transgene. The mutant human protein was properly localized in myelinating Schwann cells in multiple transgenic lines and did not alter the localization of other components of paranodes and incisures. Finally, both the C280G and the S281x mutants appeared to "rescue" the phenotype of Gjb1-null mice, because transgene-positive male mice had significantly fewer abnormally myelinated axons than did their transgene-negative male littermates. These results indicate that Cx32 is prenylated, but that prenylation is not required for proper trafficking of Cx32 and perhaps not even for certain aspects of its function, in myelinating Schwann cells.
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Affiliation(s)
- Yan Huang
- Department of Neurology, The University of Pennsylvania Medical Center, Philadelphia, Pennsylvania 19104, USA.
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33
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Fukata M, Fukata Y, Adesnik H, Nicoll RA, Bredt DS. Identification of PSD-95 palmitoylating enzymes. Neuron 2005; 44:987-96. [PMID: 15603741 DOI: 10.1016/j.neuron.2004.12.005] [Citation(s) in RCA: 421] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2004] [Revised: 10/04/2004] [Accepted: 11/23/2004] [Indexed: 11/19/2022]
Abstract
Palmitoylation is a lipid modification that plays a critical role in protein trafficking and function throughout the nervous system. Palmitoylation of PSD-95 is essential for its regulation of AMPA receptors and synaptic plasticity. The enzymes that mediate palmitoyl acyl transfer to PSD-95 have not yet been identified; however, proteins containing a DHHC cysteine-rich domain mediate palmitoyl acyl transferase activity in yeast. Here, we isolated 23 mammalian DHHC proteins and found that a subset specifically palmitoylated PSD-95 in vitro and in vivo. These PSD-95 palmitoyl transferases (P-PATs) showed substrate specificity, as they did not all enhance palmitoylation of Lck, SNAP-25b, Galpha(s), or H-Ras in cultured cells. Inhibition of P-PAT activity in neurons reduced palmitoylation and synaptic clustering of PSD-95 and diminished AMPA receptor-mediated neurotransmission. This study suggests that P-PATs regulate synaptic function through PSD-95 palmitoylation.
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Affiliation(s)
- Masaki Fukata
- Department of Physiology, University of California at San Francisco, San Francisco, California 94143, USA
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34
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Hartman HL, Bowers KE, Fierke CA. Lysine beta311 of protein geranylgeranyltransferase type I partially replaces magnesium. J Biol Chem 2004; 279:30546-53. [PMID: 15131129 DOI: 10.1074/jbc.m403469200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein geranylgeranyltransferase type I (GGTase I) catalyzes the attachment of a geranylgeranyl lipid group near the carboxyl terminus of protein substrates. Unlike protein farnesyltransferase (FTase) and protein geranylgeranyltransferase type II, which require both Zn(II) and Mg(II) for maximal turnover, GGTase I turnover is dependent only on Zn(II). In FTase, the magnesium ion is coordinated by aspartate beta352 and the diphosphate of farnesyl diphosphate to stabilize the developing charge in the transition state (Pickett, J. S., Bowers, K. E., and Fierke, C. A. (2003) J. Biol. Chem. 278, 51243-51250). In GGTase I, lysine beta311 is substituted for this aspartate and is proposed to replace the catalytic function of Mg(II) (Taylor, J. S., Reid, T. S., Terry, K. L., Casey, P. J., and Beese, L. S. (2003) EMBO J. 22, 5963-5974). Here we demonstrate that the prenylation rate constant catalyzed by wild type GGTase I (k(chem) = 0.18 +/- 0.02 s(-1)) is not dependent on Mg(II), is approximately 20-fold slower than the maximal rate constant catalyzed by FTase, and has a single pKa of 6.4 +/- 0.1, likely reflecting deprotonation of the peptide thiol. Mutation of lysine beta311 in GGTase I to alanine (Kbeta311A) or aspartate (Kbeta311D) decreases the k(chem) in the absence of magnesium 9-41-fold without significantly affecting the binding affinity of either substrate. Furthermore, the geranylgeranylation rate constant is enhanced by the addition of Mg(II) for Kbeta311A and Kbeta311D GGTase I 2-5-fold compared with wild type GGTase I with K(Mg) of 140 +/- 10 mm and 6.4 +/- 0.8 mm, respectively. These results demonstrate that lysine beta311 of GGTase I partially replaces the catalytic function of Mg(II) observed in FTase.
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Affiliation(s)
- Heather L Hartman
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, USA
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35
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Somlyo AP, Somlyo AV. Ca2+ sensitivity of smooth muscle and nonmuscle myosin II: modulated by G proteins, kinases, and myosin phosphatase. Physiol Rev 2003; 83:1325-58. [PMID: 14506307 DOI: 10.1152/physrev.00023.2003] [Citation(s) in RCA: 1528] [Impact Index Per Article: 72.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Ca2+ sensitivity of smooth muscle and nonmuscle myosin II reflects the ratio of activities of myosin light-chain kinase (MLCK) to myosin light-chain phosphatase (MLCP) and is a major, regulated determinant of numerous cellular processes. We conclude that the majority of phenotypes attributed to the monomeric G protein RhoA and mediated by its effector, Rho-kinase (ROK), reflect Ca2+ sensitization: inhibition of myosin II dephosphorylation in the presence of basal (Ca2+ dependent or independent) or increased MLCK activity. We outline the pathway from receptors through trimeric G proteins (Galphaq, Galpha12, Galpha13) to activation, by guanine nucleotide exchange factors (GEFs), from GDP. RhoA. GDI to GTP. RhoA and hence to ROK through a mechanism involving association of GEF, RhoA, and ROK in multimolecular complexes at the lipid cell membrane. Specific domains of GEFs interact with trimeric G proteins, and some GEFs are activated by Tyr kinases whose inhibition can inhibit Rho signaling. Inhibition of MLCP, directly by ROK or by phosphorylation of the phosphatase inhibitor CPI-17, increases phosphorylation of the myosin II regulatory light chain and thus the activity of smooth muscle and nonmuscle actomyosin ATPase and motility. We summarize relevant effects of p21-activated kinase, LIM-kinase, and focal adhesion kinase. Mechanisms of Ca2+ desensitization are outlined with emphasis on the antagonism between cGMP-activated kinase and the RhoA/ROK pathway. We suggest that the RhoA/ROK pathway is constitutively active in a number of organs under physiological conditions; its aberrations play major roles in several disease states, particularly impacting on Ca2+ sensitization of smooth muscle in hypertension and possibly asthma and on cancer neoangiogenesis and cancer progression. It is a potentially important therapeutic target and a subject for translational research.
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Affiliation(s)
- Andrew P Somlyo
- Dept. of Molecular Physiology and Biological Physics, Univ. of Virginia, PO Box 800736, Charlottesville, VA 22908-0736.
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36
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Yu F, Cai Y, Kaushik R, Yang X, Chia W. Distinct roles of Galphai and Gbeta13F subunits of the heterotrimeric G protein complex in the mediation of Drosophila neuroblast asymmetric divisions. J Cell Biol 2003; 162:623-33. [PMID: 12925708 PMCID: PMC2173805 DOI: 10.1083/jcb.200303174] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The asymmetric division of Drosophila neuroblasts involves the basal localization of cell fate determinants and the generation of an asymmetric, apicobasally oriented mitotic spindle that leads to the formation of two daughter cells of unequal size. These features are thought to be controlled by an apically localized protein complex comprising of two signaling pathways: Bazooka/Drosophila atypical PKC/Inscuteable/DmPar6 and Partner of inscuteable (Pins)/Galphai; in addition, Gbeta13F is also required. However, the role of Galphai and the hierarchical relationship between the G protein subunits and apical components are not well defined. Here we describe the isolation of Galphai mutants and show that Galphai and Gbeta13F play distinct roles. Galphai is required for Pins to localize to the cortex, and the effects of loss of Galphai or pins are highly similar, supporting the idea that Pins/Galphai act together to mediate various aspects of neuroblast asymmetric division. In contrast, Gbeta13F appears to regulate the asymmetric localization/stability of all apical components, and Gbeta13F loss of function exhibits phenotypes resembling those seen when both apical pathways have been compromised, suggesting that it acts upstream of the apical pathways. Importantly, our results have also revealed a novel aspect of apical complex function, that is, the two apical pathways act redundantly to suppress the formation of basal astral microtubules in neuroblasts.
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Affiliation(s)
- Fengwei Yu
- MRC Centre for Developmental Neurobiology, 4th Fl., New Hunts House, Guy's Campus, King's College London, London SE1 1UL, UK
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37
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Fuse N, Hisata K, Katzen AL, Matsuzaki F. Heterotrimeric G proteins regulate daughter cell size asymmetry in Drosophila neuroblast divisions. Curr Biol 2003; 13:947-54. [PMID: 12781133 DOI: 10.1016/s0960-9822(03)00334-8] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Cell division often generates unequally sized daughter cells by off-center cleavages, which are due to either displacement of mitotic spindles or their asymmetry. Drosophila neuroblasts predominantly use the latter mechanism to divide into a large apical neuroblast and a small basal ganglion mother cell (GMC), where the neural fate determinants segregate. Apically localized components regulate both the spindle asymmetry and the localization of the determinants. Here, we show that asymmetric spindle formation depends on signaling mediated by the G beta subunit of heterotrimeric G proteins. G beta 13F distributes throughout the neuroblast cortex. Its lack induces a large symmetric spindle and causes division into nearly equal-sized cells with normal segregation of the determinants. In contrast, elevated G beta 13F activity generates a small spindle, suggesting that this factor suppresses spindle development. Depletion of the apical components also results in the formation of a small symmetric spindle at metaphase. Therefore, the apical components and G beta 13F affect the mitotic spindle shape oppositely. We propose that differential activation of G beta signaling biases spindle development within neuroblasts and thereby causes asymmetric spindles. Furthermore, the multiple equal cleavages of G beta mutant neuroblasts accompany neural defects; this finding suggests indispensable roles of eccentric division in assuring the stem cell properties of neuroblasts.
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Affiliation(s)
- Naoyuki Fuse
- Laboratory for Cell Asymmetry, Center for Developmental Biology, RIKEN, Chuou-ku, Kobe 650-0047, Japan
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38
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Gu JL, Lu W, Xia C, Wu X, Liu M. Regulation of hematopoietic-specific G-protein Galpha15 and Galpha16 by protein kinase C. J Cell Biochem 2003; 88:1101-11. [PMID: 12647293 DOI: 10.1002/jcb.10455] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Heterotrimeric G proteins mediate cell growth and differentiation by coupling cell surface receptors to intracellular effector enzymes. The G-protein alpha subunit, Galpha(16), and its murine homologue Galpha(15), are expressed specifically in hematopoietic cells and their expression is highly regulated during differentiation of normal and leukemic cells. In this study, we examined the phosphorylation of Galpha(15)/Galpha(16) and its role in receptor and effector coupling. We observed a PMA-stimulated intact cell phosphorylation of Galpha(15) in COS7 cells transfected with Galpha(15) and protein kinase Calpha (PKCalpha), and phosphorylation of endogenous Galpha(16) in HL60 cells. We also showed that peptides derived from the two G-proteins were phosphorylated in vitro using purified brain PKC. Furthermore, we identified the putative phosphorylation site and showed that mutation or deletion of this PKC phosphorylation site inhibited phospholipase C (PLC) activation. The behavior of double mutants with the constitutively active G-protein mutation (QL-mutant) and mutation in the putative phosphorylation site suggests that the phosphorylation site of Galpha(15/16) is essential for receptor-coupled activation of PLC, but not for direct interaction of the G-protein with PLC-beta.
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Affiliation(s)
- Jennifer L Gu
- Division of Biology, California Institute of Technology, Pasadena, California 91125, USA
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39
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Abstract
Covalent lipid attachments are essential co- and post-translational modifications for signalling proteins. Galpha(s), the alpha-subunit of the heterotrimeric G protein that activates adenylyl cyclase, is known to be palmitoylated at the third N-terminal amino acid, a cysteine. Palmitoylation is involved in anchoring Galpha(s) to the membrane by increasing its intrinsic hydrophobicity. We identified by mass spectrometry a second, functionally even more important, covalent modification. It consists of another palmitoyl residue attached to the preceding glycine (Gly(2)). Palmitoylation at this position has profound consequences for levels of signal transduction. It sensitizes the cell up to 200-fold for adenylyl cyclase-stimulating agents. The inhibitory inputs mediated by Galpha(i) are downregulated to <10%. Thereby, Gly(2)-palmitoylation of Galpha(s) relieves cellular stimulation at the level of adenylyl cyclase whereas it renders the inhibitory modulation via Galpha(i) more difficult.
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Affiliation(s)
- Christiane Kleuss
- Institut für Pharmakologie, Freie Universität Berlin, Thielallee 67–73, 14195 Berlin and
Forschungsinstitut für Molekulare Pharmakologie, Campus Berlin Buch, Robert-Rössle-Strasse 10, 13125 Berlin-Buch, Germany Corresponding author e-mail:
| | - Eberhard Krause
- Institut für Pharmakologie, Freie Universität Berlin, Thielallee 67–73, 14195 Berlin and
Forschungsinstitut für Molekulare Pharmakologie, Campus Berlin Buch, Robert-Rössle-Strasse 10, 13125 Berlin-Buch, Germany Corresponding author e-mail:
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40
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Watson RT, Furukawa M, Chiang SH, Boeglin D, Kanzaki M, Saltiel AR, Pessin JE. The exocytotic trafficking of TC10 occurs through both classical and nonclassical secretory transport pathways in 3T3L1 adipocytes. Mol Cell Biol 2003; 23:961-74. [PMID: 12529401 PMCID: PMC140699 DOI: 10.1128/mcb.23.3.961-974.2003] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To examine the structural determinants necessary for TC10 trafficking, localization, and function in adipocytes, we generated a series of point mutations in the carboxyl-terminal targeting domain of TC10. Wild-type TC10 (TC10/WT) localized to secretory membrane compartments and caveolin-positive lipid raft microdomains at the plasma membrane. Expression of a TC10/C206S point mutant resulted in a trafficking and localization pattern that was indistinguishable from that of TC10/WT. In contrast, although TC10/C209S or the double TC10/C206,209S mutant was plasma membrane localized, it was excluded from both the secretory membrane system and the lipid raft compartments. Surprisingly, inhibition of Golgi membrane transport with brefeldin A did not prevent plasma membrane localization of TC10 or H-Ras. Moreover, inhibition of trans-Golgi network exit with a 19 degrees C temperature block did not prevent the trafficking of TC10 or H-Ras to the plasma membrane. These data demonstrate that TC10 and H-Ras can both traffic to the plasma membrane by at least two distinct transport mechanisms in adipocytes, one dependent upon intracellular membrane transport and another independent of the classical secretory membrane system. Moreover, the transport through the secretory pathway is necessary for the localization of TC10 to lipid raft microdomains at the plasma membrane.
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Affiliation(s)
- Robert T Watson
- Department of Physiology and Biophysics, The University of Iowa, Iowa City, Iowa 52242, USA
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41
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el-Husseini AED, Bredt DS. Protein palmitoylation: a regulator of neuronal development and function. Nat Rev Neurosci 2002; 3:791-802. [PMID: 12360323 DOI: 10.1038/nrn940] [Citation(s) in RCA: 274] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Alaa el-Din el-Husseini
- Kinsmen Laboratory, Department of Psychiatry and the Brain Research Centre, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
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42
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Stanfield PR, Nakajima S, Nakajima Y. Constitutively active and G-protein coupled inward rectifier K+ channels: Kir2.0 and Kir3.0. Rev Physiol Biochem Pharmacol 2002; 145:47-179. [PMID: 12224528 DOI: 10.1007/bfb0116431] [Citation(s) in RCA: 123] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Peter R Stanfield
- Molecular Physiology Group, Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK
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43
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Hirafuji M, Machida T, Tsunoda M, Miyamoto A, Minami M. Docosahexaenoic acid potentiates interleukin-1beta induction of nitric oxide synthase through mechanism involving p44/42 MAPK activation in rat vascular smooth muscle cells. Br J Pharmacol 2002; 136:613-9. [PMID: 12055140 PMCID: PMC1573387 DOI: 10.1038/sj.bjp.0704768] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The effect of docosahexaenoic acid (DHA) on nitric oxide (NO) production and inducible NO synthase (iNOS) expression induced by interleukin (IL)-1beta, and whether the effect of DHA is related to its effect on mitogen-activated protein kinase (MAPK) activation were investigated in cultured rat vascular smooth muscle cells (VSMCs). DHA and eicosapentaenoic acid (EPA), although less potent, increased the NO production induced by IL-1beta (3 ng ml(-1)) in a concentration-dependent manner (3 - 30 microM) Arachidonic acid had no significant effect. The stimulatory effect of DHA (30 microM) on the NO production was more obvious at lower concentrations of IL-1beta. IL-1beta induced iNOS protein and mRNA expressions, which were significantly potentiated by DHA. EPA (30 microM) had a tendency to increase the iNOS protein and mRNA expressions, but arachidonic acid had no effect. IL-1beta-induced iNOS protein expression was significantly inhibited by PD 98059 (10 microM), a selective inhibitor of p44/42 MAPK kinase, both in the absence and the presence of DHA. SB 203580 (10 microM), a selective inhibitor of p38 MAPK activity, had no significant effect, although had a tendency to inhibit slightly. IL-1beta increased the phosphorylation of p44/42 MAPK, while it did not apparently increase the phosphorylation of p38 MAPK. DHA significantly potentiated the IL-1beta-induced phosphorylation of p44/42 MAPK, while it had no significant effect on the phosphorylation of p38 MAPK. These results suggest that DHA increases NO production by potentiating iNOS expression induced by IL-1beta through mechanism involving p44/42 MAPK signalling cascade in rat VSMCs. The present study may contribute to the understanding of basic mechanisms underlying the beneficial effects of DHA on various cardiovascular disorders.
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MESH Headings
- Animals
- Arachidonic Acid/pharmacology
- Blotting, Western
- Cells, Cultured
- Docosahexaenoic Acids/pharmacology
- Eicosapentaenoic Acid/pharmacology
- Enzyme Activation
- Interleukin-1/metabolism
- Interleukin-1/pharmacology
- Mitogen-Activated Protein Kinase 1/antagonists & inhibitors
- Mitogen-Activated Protein Kinase 1/metabolism
- Mitogen-Activated Protein Kinase 3
- Mitogen-Activated Protein Kinases/antagonists & inhibitors
- Mitogen-Activated Protein Kinases/metabolism
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/enzymology
- Nitric Oxide/biosynthesis
- Nitric Oxide Synthase/biosynthesis
- Nitric Oxide Synthase/genetics
- Nitric Oxide Synthase Type II
- RNA, Messenger/biosynthesis
- Rats
- Rats, Inbred WKY
- Reverse Transcriptase Polymerase Chain Reaction
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Affiliation(s)
- Masahiko Hirafuji
- Department of Pharmacology, Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido 061-0293, Japan.
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44
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Gehrmann J, Meister M, Maguire CT, Martins DC, Hammer PE, Neer EJ, Berul CI, Mende U. Impaired parasympathetic heart rate control in mice with a reduction of functional G protein betagamma-subunits. Am J Physiol Heart Circ Physiol 2002; 282:H445-56. [PMID: 11788391 DOI: 10.1152/ajpheart.00565.2001] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Acetylcholine released on parasympathetic stimulation slows heart rate through activation of muscarinic receptors on the sinus nodal cells and subsequent opening of the atrial muscarinic potassium channel (K(ACh)). K(ACh) is directly activated by G protein betagamma-subunits. To elucidate the physiological role of Gbetagamma for the regulation of heart rate and electrophysiological function in vivo, we created transgenic mice with a reduced amount of membrane-bound Gbeta protein by overexpressing nonprenylated Ggamma(2)-subunits in their hearts using the alpha-myosin heavy chain promoter. At baseline and after muscarinic stimulation with carbachol, heart rate and heart rate variability were determined with electrocardiogram telemetry in conscious mice and in vivo intracardiac electrophysiological studies in anesthetized mice. Reduction of the amount of functional Gbetagamma protein by >50% caused a pronounced blunting of the carbachol-induced bradycardia as well as the increases in time- and frequency-domain indexes of heart rate variability and baroreflex sensitivity that were observed in wild types. In addition, sinus node recovery time and inducibility of atrial arrhythmias were reduced in transgenic mice. Our data demonstrate in vivo that Gbetagamma plays a crucial role for parasympathetic heart rate control, sinus node automaticity, and atrial arrhythmia vulnerability.
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Affiliation(s)
- Josef Gehrmann
- Department of Medicine, Harvard Medical School, Boston, Massachusetts 02115, USA
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45
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Degraeve F, Bolla M, Blaie S, Créminon C, Quéré I, Boquet P, Lévy-Toledano S, Bertoglio J, Habib A. Modulation of COX-2 expression by statins in human aortic smooth muscle cells. Involvement of geranylgeranylated proteins. J Biol Chem 2001; 276:46849-55. [PMID: 11591701 DOI: 10.1074/jbc.m104197200] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Cyclooxygenase (COX)-2 and COX-1 play an important role in prostacyclin production in vessels and participate in maintaining vascular homeostasis. Statins are inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase, which is crucial in cholesterol biosynthesis. Recently, cholesterol-independent effects of statins have been described. In this study, we evaluated the effect of two inhibitors of HMG CoA reductase, mevastatin and lovastatin, on the production of prostacyclin and the expression of COX in human aortic smooth muscle cells. Treatment of cells with 25 microm mevastatin or lovastatin resulted in the induction of COX-2 and increase in prostacyclin production. Mevalonate, the direct metabolite of HMG CoA reductase, and geranylgeranyl-pyrophosphate reversed this effect. GGTI-286, a selective inhibitor of geranylgeranyltransferases, increased COX-2 expression and prostacyclin formation, thus indicating the involvement of geranylgeranylated proteins in the down-regulation of COX-2. Furthermore, Clostridium difficile toxin B, an inhibitor of the Rho GTP-binding protein family, the Rho selective inhibitor C3 transferase, and Y-27632, a selective inhibitor of the Rho-associated kinases, targets of Rho A, increased COX-2 expression whereas the activator of the Rho GTPase, the cytotoxic necrotizing factor 1, blocked interlukin-1alpha-dependent COX-2 induction. These results demonstrate that statins up-regulate COX-2 expression and subsequent prostacyclin formation in human aortic smooth muscle cells in part through inhibition of Rho.
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Affiliation(s)
- F Degraeve
- Commissariat à l'Energie Atomique (CEA), Service de Pharmacologie et d'Immunologie, 91191 Gif sur Yvette, France
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46
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Ibrahim M, Azzouz N, Gerold P, Schwarz RT. Identification and characterisation of Toxoplasma gondii protein farnesyltransferase. Int J Parasitol 2001; 31:1489-97. [PMID: 11595236 DOI: 10.1016/s0020-7519(01)00268-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Prenylated proteins are involved in the regulation of DNA replication and cell cycling and have important roles in the regulation of cell proliferation. Protein farnesyltransferase and protein geranylgeranyltransferase are the two enzymes responsible for catalysing isoprene lipid modifications. Recently these enzymes have been targets for the development of cancer chemotherapeutics. Using metabolic labelling we identified isoprenylated proteins which suggests the presence of protein farnesyltransferase in Toxoplasma gondii. T. gondii protein farnesyltransferase is heat-labile and requires Mg(2+) and Zn(2+) ions for full activity. Peptidomimetic analogues as well as short synthetic peptides were tested in vitro as possible competitors for farnesyltransferase substrates. We found that the synthetic peptide (KTSCVIA) specifically inhibited T. gondiiprotein farnesyltransferase but not mammalian (HeLa cells) farnesyltransferase. Therefore this study suggests the possible development of specific inhibitors of T. gondiiprotein farnesyltransferase as an approach to parasitic protozoa therapy.
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Affiliation(s)
- M Ibrahim
- Zentrum für Hygiene und Medizinische Mikrobiologie, Philipps-Universität Marburg, Robert-Koch-Strasse 17, 35037 Marburg, Germany
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47
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Guzzi F, Zanchetta D, Chini B, Parenti M. Thioacylation is required for targeting G-protein subunit G(o1alpha) to detergent-insoluble caveolin-containing membrane domains. Biochem J 2001; 355:323-31. [PMID: 11284718 PMCID: PMC1221742 DOI: 10.1042/0264-6021:3550323] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
alpha-Subunits of heterotrimeric G(i)-like proteins (alpha(i), alpha(o) and alpha(z)) associate with the cytoplasmic leaflet of the plasma membrane by means of N-terminally linked myristic acid and palmitic acid. An additional role for palmitate has been recently suggested by the observation that fusion with the palmitoylated N-terminus of alpha(i1) relocalizes cytosolic green-fluorescent-protein reporter to low buoyancy, Triton-insoluble membrane domains (TIFF; Triton-insoluble floating fraction), enriched with caveolin-1 [Galbiati, Volonté, Meani, Milligan, Lublin, Lisanti and Parenti (1999) J. Biol. Chem 274, 5843-5850]. Here we show that, upon transient expression in transfected COS-7 cells, myristoylated and palmitoylated alpha(o) (alpha(o)wt, where wt is wild-type) is exclusively found in TIFF, from where non-palmitoylated alpha(o)wt and alpha(o)C3S (Cys(3)-->Ser) mutant are excluded. Moreover, alpha(o) fused to N-terminally truncated human vasopressin V2 receptor (V2TR-alpha(o)), lacking myristate and palmitate, still localizes at the plasma membrane by means of first transmembrane helix of V2R, but is excluded from TIFF. Likewise, alpha(o)C3S does not partition into TIFF, even when its membrane avidity is enhanced by co-expression of betagamma-subunits. Thus membrane association, in the absence of added palmitate, is not sufficient to confer partitioning of alpha(o) within TIFF, suggesting that palmitoylation is a signal for membrane compartmentalization of dually acylated alpha-subunits.
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Affiliation(s)
- F Guzzi
- Department of Experimental and Environmental Medicine and Medical Biotechnologies, University of Milano-Bicocca, Via Cadore 48, 20052 Monza, Italy
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48
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Ishimura R, Yoshida K, Kimura H, Dohmae N, Takio K, Ogawa T, Tanaka S, Shiota K. Stage-specific modification of G protein beta subunits in rat placenta. Mol Cell Endocrinol 2001; 174:77-89. [PMID: 11306174 DOI: 10.1016/s0303-7207(00)00451-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
We previously analysed the plasma membrane proteins of rat placenta and prepared a database of 150 plasma membrane proteins, expressed in a stage-specific manner, utilizing two-dimensional gel electrophoresis (2D/E) [Mol. Cell. Endocrinol. 115(1995)149]. In this study, we focused on the proteins, tentatively named psL-I (MW 36.2 kDa, pI 5.3) and psL-II (35.9 kDa, 5.3), which were expressed mainly in late pregnancy. Close to psL-I and psL-II on 2D/E gels, we also recognized more abundant proteins [psC-I (36.2 kDa, 5.4) and psC-II (35.9 kDa, 5.4), respectively] arranged side by side with the same MW but different pI. Expression of psL-I and psL-II was detected only in junctional zone of placenta, whereas psC-I and psC-II were expressed in both labyrinth and junctional zones. In addition, psL-I and psL-II began to increase on day 16 of pregnancy and peaked at term, whereas expression of psC-I and psC-II was relatively constant. The analysis of these four proteins (psL-I, psL-II, psC-I and psC-II) by preparative 2D/E, peptide mapping, amino acid sequence and mass spectrometry (MALDI-TOF-MS) revealed that psC-I was a G protein beta1 subunit, and psC-II was a beta2 subunit, and showed that psL-I and psL-II were molecular modified forms of psC-I and psC-II, respectively. Expression of these G protein beta subunits (psL-I, psL-II, psC-I and psC-II) was also observed in rat choriocarcinoma cells, Rcho-1 cells. Expression of psC-I and psC-II was much higher than those of psL-I and psL-II, and their level was relatively constant regardless of the stage of differentiation in vitro. Interestingly, expression of psL-I and psL-II gradually increased in association with the differentiation. Since the expression of beta1 and beta2 subunit proteins and their mRNAs was constant during the process of differentiation in Rcho-1 cells, the expression of these lower pI forms of G protein subunits (psL-I and psL-II) was thought to be post-translationally regulated. In conclusion, there are modified forms of G protein beta1 and beta2 subunits, in the placenta and Rcho-1 cells, which are expressed in a pregnancy-stage or differentiation stage specific manner.
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Affiliation(s)
- R Ishimura
- Laboratory of Cellular Biochemistry, Department of Veterinary Medical Sciences/Animal Resource Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, 113-8657, Tokyo, Japan
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Landry S, Hoffman CS. The git5 Gbeta and git11 Ggamma form an atypical Gbetagamma dimer acting in the fission yeast glucose/cAMP pathway. Genetics 2001; 157:1159-68. [PMID: 11238401 PMCID: PMC1461563 DOI: 10.1093/genetics/157.3.1159] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Fission yeast adenylate cyclase, like mammalian adenylate cyclases, is regulated by a heterotrimeric G protein. The gpa2 Galpha and git5 Gbeta are both required for glucose-triggered cAMP signaling. The git5 Gbeta is a unique member of the Gbeta family in that it lacks an amino-terminal coiled-coil domain shown to be essential for mammalian Gbeta folding and interaction with Ggamma subunits. Using a git5 bait in a two-hybrid screen, we identified the git11 Ggamma gene. Co-immunoprecipitation studies confirm the composition of this Gbetagamma dimer. Cells deleted for git11 are defective in glucose repression of both fbp1 transcription and sexual development, resembling cells lacking either the gpa2 Galpha or the git5 Gbeta. Overexpression of the gpa2 Galpha partially suppresses loss of either the git5 Gbeta or the git11 Ggamma, while mutational activation of the Galpha fully suppresses loss of either Gbeta or Ggamma. Deletion of gpa2 (Galpha), git5 (Gbeta), or git11 (Ggamma) confer quantitatively distinct effects on fbp1 repression, indicating that the gpa2 Galpha subunit remains partially active in the absence of the Gbetagamma dimer and that the git5 Gbeta subunit remains partially active in the absence of the git11 Ggamma subunit. The addition of the CAAX box from the git11 Ggamma to the carboxy-terminus of the git5 Gbeta partially suppresses the loss of the Ggamma. Thus the Ggamma in this system is presumably required for localization of the Gbetagamma dimer but not for folding of the Gbeta subunit. In mammalian cells, the essential roles of the Gbeta amino-terminal coiled-coil domains and Ggamma partners in Gbeta folding may therefore reflect a mechanism used by cells that express multiple forms of both Gbeta and Ggamma subunits to regulate the composition and activity of its G proteins.
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Affiliation(s)
- S Landry
- Department of Biology, Boston College, Chestnut Hill, Massachusetts 02467, USA
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Mason MG, Botella JR. Completing the heterotrimer: isolation and characterization of an Arabidopsis thaliana G protein gamma-subunit cDNA. Proc Natl Acad Sci U S A 2000; 97:14784-8. [PMID: 11121078 PMCID: PMC18996 DOI: 10.1073/pnas.97.26.14784] [Citation(s) in RCA: 141] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Heterotrimeric G proteins consist of three subunits (alpha, beta, and gamma). alpha- and beta- subunits have been previously cloned in plants, but the gamma-subunit has remained elusive. To isolate the gamma-subunit of a plant heterotrimeric G protein an Arabidopsis thaliana yeast two-hybrid library was screened by using a tobacco G-beta-subunit as the bait protein. One positive clone (AGG1) was isolated several times; it displays significant homology to the conserved domains of mammalian gamma-subunits. The predicted AGG1 protein sequence contains all of the typical characteristics of mammalian gamma-subunits such as small size (98 amino acids, 10.8 kDa), presence of a C-terminal CAAX box to direct isoprenyl modification, and an N-terminal alpha-helix region capable of forming a coiled-coil interaction with the beta-subunit. Northern and Southern analyses showed that AGG1 is a single-copy gene in Arabidopsis with a similar expression pattern to the Arabidopsis beta-subunit, AGB1 [Weiss, C. A., Garnaat, C. W., Mukai, K., Hu, Y. & Ma, H. (1994) Proc. Natl. Acad. Sci. USA 91, 9554-9558]. By using the yeast two-hybrid system, we show that AGG1 strongly interacts with tobacco and Arabidopsis beta-subunits. The in vivo results have been confirmed by using in vitro methods to prove the interaction between AGG1 and the Arabidopsis beta-subunit. As previously observed in mammalian systems, both the coiled-coil domain and the WD repeat regions of the beta-subunit are essential for AGG1 interaction. Also in agreement with previous observations, the removal of the N-terminal alpha-helix of the AGG1 greatly reduces but does not completely block the interaction.
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Affiliation(s)
- M G Mason
- Plant Genetic Engineering Laboratory, Department of Botany, University of Queensland, Brisbane, Queensland 4072, Australia
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