1
|
Kaur A, Madhu, Sharma A, Singh K, Upadhyay SK. Investigation of two-pore K + (TPK) channels in Triticum aestivum L. suggests their role in stress response. Heliyon 2024; 10:e27814. [PMID: 38533012 PMCID: PMC10963239 DOI: 10.1016/j.heliyon.2024.e27814] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 02/28/2024] [Accepted: 03/07/2024] [Indexed: 03/28/2024] Open
Abstract
Two-pore K+ (TPK) channels are voltage-independent and involved in stress response in plants. Herein, we identified 12 TaTPK genes located on nine chromosomes in the Triticum aestivum genome. The majority of TaTPK genes comprised two exons. Each TaTPK channel comprised four transmembrane (TM) helices, N- and C-terminal ion-channel domains, two EF-hand domains and one 14-3-3 binding site. Additionally, highly conserved 'GYGD' motif responsible for K+ ion specificity, was found in between the TMs in both the ion-channel domains. Nine TaTPK channels were predicted to be localised at the plasma membrane, while three were vacuolar. The protein-protein and protein-chemical interactions indicated the coordinated functioning of the TaTPK channels with the other K+ transporters and their possible interaction with the Ca2+-signaling pathway. Expression studies suggested their importance in both vegetative and reproductive tissues development. Significantly modulated expression of various TaTPK genes during heat, drought, combined heat and drought and salt stresses, and after fungal infestation, depicted their function in stress responses. The miRNAs and transcription factors interaction analyses suggested their role in the hormone, light, growth and development-related, and stress-responsive signaling cascades. The current study suggested vital functions of various TaTPK genes, especially in stress response, and would provide an opportunity for their detailed characterization in future studies.
Collapse
Affiliation(s)
- Amandeep Kaur
- Department of Botany, Panjab University, Chandigarh, India, 160014
| | - Madhu
- Department of Botany, Panjab University, Chandigarh, India, 160014
| | - Alok Sharma
- Department of Botany, Panjab University, Chandigarh, India, 160014
- Regional Ayurveda Research Institute, Gwalior, Madhya Pradesh, 474001, India
| | - Kashmir Singh
- Department of Biotechnology, Panjab University, Chandigarh, India
| | | |
Collapse
|
2
|
Vlahos AE, Call CC, Kadaba SE, Guo S, Gao XJ. Compact Programmable Control of Protein Secretion in Mammalian Cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.04.560774. [PMID: 37873144 PMCID: PMC10592972 DOI: 10.1101/2023.10.04.560774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Synthetic biology currently holds immense potential to engineer the spatiotemporal control of intercellular signals for biomedicine. Programming behaviors using protein-based circuits has advantages over traditional gene circuits such as compact delivery and direct interactions with signaling proteins. Previously, we described a generalizable platform called RELEASE to enable the control of intercellular signaling through the proteolytic removal of ER-retention motifs compatible with pre-existing protease-based circuits. However, these tools lacked the ability to reliably program complex expression profiles and required numerous proteases, limiting delivery options. Here, we harness the recruitment and antagonistic behavior of endogenous 14-3-3 proteins to create RELEASE-NOT to turn off protein secretion in response to protease activity. By combining RELEASE and RELEASE-NOT, we establish a suite of protein-level processing and output modules called Compact RELEASE (compRELEASE). This innovation enables functions such as logic processing and analog signal filtering using a single input protease. Furthermore, we demonstrate the compactness of the post-translational design by using polycistronic single transcripts to engineer cells to control protein secretion via lentiviral integration and leverage mRNA delivery to selectively express cell surface proteins only in engineered cells harboring inducible proteases. CompRELEASE enables complex control of protein secretion and enhances the potential of synthetic protein circuits for therapeutic applications, while minimizing the overall genetic payload.
Collapse
Affiliation(s)
- Alexander E. Vlahos
- Department of Chemical Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Connor C. Call
- Department of Chemical Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Samarth E. Kadaba
- Department of Chemical Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Siqi Guo
- Department of Chemical Engineering, Stanford University, Stanford, CA, 94305, USA
- The Chinese Undergraduate Visiting Research (UGVR) Program, Stanford, CA, 94305, USA
| | - Xiaojing J. Gao
- Department of Chemical Engineering, Stanford University, Stanford, CA, 94305, USA
- Neurosciences Interdepartmental Program, Stanford University, Stanford, CA, 94305, USA
| |
Collapse
|
3
|
Nguyen NH, Brodsky JL. The cellular pathways that maintain the quality control and transport of diverse potassium channels. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2023; 1866:194908. [PMID: 36638864 PMCID: PMC9908860 DOI: 10.1016/j.bbagrm.2023.194908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 12/20/2022] [Accepted: 01/03/2023] [Indexed: 01/12/2023]
Abstract
Potassium channels are multi-subunit transmembrane proteins that permit the selective passage of potassium and play fundamental roles in physiological processes, such as action potentials in the nervous system and organismal salt and water homeostasis, which is mediated by the kidney. Like all ion channels, newly translated potassium channels enter the endoplasmic reticulum (ER) and undergo the error-prone process of acquiring post-translational modifications, folding into their native conformations, assembling with other subunits, and trafficking through the secretory pathway to reach their final destinations, most commonly the plasma membrane. Disruptions in these processes can result in detrimental consequences, including various human diseases. Thus, multiple quality control checkpoints evolved to guide potassium channels through the secretory pathway and clear potentially toxic, aggregation-prone misfolded species. We will summarize current knowledge on the mechanisms underlying potassium channel quality control in the secretory pathway, highlight diseases associated with channel misfolding, and suggest potential therapeutic routes.
Collapse
Affiliation(s)
- Nga H Nguyen
- Department of Biological Sciences, University of Pittsburgh, A320 Langley Hall, Pittsburgh, 4249 Fifth Avenue, Pittsburgh, PA 15260, USA
| | - Jeffrey L Brodsky
- Department of Biological Sciences, University of Pittsburgh, A320 Langley Hall, Pittsburgh, 4249 Fifth Avenue, Pittsburgh, PA 15260, USA.
| |
Collapse
|
4
|
Lee GS, Zhang J, Wu Y, Zhou Y. 14-3-3 proteins promote synaptic localization of N-methyl d-aspartate receptors (NMDARs) in mouse hippocampal and cortical neurons. PLoS One 2021; 16:e0261791. [PMID: 34962957 PMCID: PMC8714094 DOI: 10.1371/journal.pone.0261791] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 12/09/2021] [Indexed: 11/19/2022] Open
Abstract
One of the core pathogenic mechanisms for schizophrenia is believed to be dysfunction in glutamatergic synaptic transmissions, particularly hypofunction of N-methyl d-aspartate receptors (NMDARs). Previously we showed that 14-3-3 functional knockout mice exhibit schizophrenia-associated behaviors accompanied by reduced synaptic NMDARs in forebrain excitatory neurons. To investigate how 14-3-3 proteins regulate synaptic localization of NMDARs, here we examined changes in levels of synaptic NMDARs upon 14-3-3 inhibition in primary neurons. Expression of 14-3-3 protein inhibitor (difopein) in primary glutamatergic cortical and hippocampal neurons resulted in lower number of synaptic puncta containing NMDARs, including the GluN1, GluN2A, or GluN2B subunits. In heterologous cells, 14-3-3 proteins enhanced surface expression of these NMDAR subunits. Furthermore, we identified that 14-3-3ζ and ε isoforms interact with NMDARs via binding to GluN2A and GluN2B subunits. Taken together, our results demonstrate that 14-3-3 proteins play a critical role in NMDAR synaptic trafficking by promoting surface delivery of NMDAR subunits GluN1, GluN2A, and GluN2B. As NMDAR hypofunctionality is known to act as a convergence point for progression of symptoms of schizophrenia, further studies on these signaling pathways may help understand how dysfunction of 14-3-3 proteins can cause NMDAR hypofunctionality and lead to schizophrenia-associated behaviors.
Collapse
Affiliation(s)
- Gloria S. Lee
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, Florida, United States of America
| | - Jiajing Zhang
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, Florida, United States of America
| | - Yuying Wu
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, Florida, United States of America
| | - Yi Zhou
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, Florida, United States of America
| |
Collapse
|
5
|
Kotthoff M, Bauer J, Haag F, Krautwurst D. Conserved C-terminal motifs in odorant receptors instruct their cell surface expression and cAMP signaling. FASEB J 2021; 35:e21274. [PMID: 33464692 DOI: 10.1096/fj.202000182rr] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 10/30/2020] [Accepted: 11/30/2020] [Indexed: 11/11/2022]
Abstract
The highly individual plasma membrane expression and cAMP signaling of odorant receptors have hampered their ligand assignment and functional characterization in test cell systems. Chaperones have been identified to support the cell surface expression of only a portion of odorant receptors, with mechanisms remaining unclear. The presence of amino acid motifs that might be responsible for odorant receptors' individual intracellular retention or cell surface expression, and thus, for cAMP signaling, is under debate: so far, no such protein motifs have been suggested. Here, we demonstrate the existence of highly conserved C-terminal amino acid motifs, which discriminate at least between class-I and class-II odorant receptors, with their numbers of motifs increasing during evolution, by comparing C-terminal protein sequences from 4808 receptors across eight species. Truncation experiments and mutation analysis of C-terminal motifs, largely overlapping with helix 8, revealed single amino acids and their combinations to have differential impact on the cell surface expression and on stimulus-dependent cAMP signaling of odorant receptors in NxG 108CC15 cells. Our results demonstrate class-specific and individual C-terminal motif equipment of odorant receptors, which instruct their functional expression in a test cell system, and in situ may regulate their individual cell surface expression and intracellular cAMP signaling.
Collapse
Affiliation(s)
| | - Julia Bauer
- Leibniz-Institute for Food Systems Biology at the Technical University of Munich, Freising, Germany
| | - Franziska Haag
- Leibniz-Institute for Food Systems Biology at the Technical University of Munich, Freising, Germany
| | - Dietmar Krautwurst
- Leibniz-Institute for Food Systems Biology at the Technical University of Munich, Freising, Germany
| |
Collapse
|
6
|
Edwards MR, Hoad M, Tsimbalyuk S, Menicucci AR, Messaoudi I, Forwood JK, Basler CF. Henipavirus W Proteins Interact with 14-3-3 To Modulate Host Gene Expression. J Virol 2020; 94:e00373-20. [PMID: 32321809 PMCID: PMC7343215 DOI: 10.1128/jvi.00373-20] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 04/12/2020] [Indexed: 01/21/2023] Open
Abstract
Nipah virus (NiV) and Hendra virus (HeV), members of the Henipavirus genus in the Paramyxoviridae family, are recently emerged, highly lethal zoonotic pathogens. The NiV and HeV nonsegmented, negative-sense RNA genomes encode nine proteins, including the W protein. Expressed from the P gene through mRNA editing, W shares a common N-terminus with P and V but has a unique C-terminus. Expressed alone, W modulates innate immune responses by several mechanisms, and elimination of W from NiV alters the course of infection in experimentally infected ferrets. However, the specific host interactions that allow W to modulate innate immunity are incompletely understood. This study demonstrates that the NiV and HeV W proteins interact with all seven isoforms of the 14-3-3 family, regulatory molecules that preferentially bind phosphorylated target proteins to regulate a wide range of cellular functions. The interaction is dependent on the penultimate amino acid residue in the W sequence, a conserved, phosphorylated serine. The cocrystal structure of the W C-terminal binding motif with 14-3-3 provides only the second structure of a complex containing a mode III interactor, which is defined as a 14-3-3 interaction with a phosphoserine/phosphothreonine at the C-termini of the target protein. Transcriptomic analysis of inducible cell lines infected with an RNA virus and expressing either wild-type W or W lacking 14-3-3 binding, identifies new functions for W. These include the regulation of cellular metabolic processes, extracellular matrix organization, and apoptosis.IMPORTANCE Nipah virus (NiV) and Hendra virus (HeV), members of the Henipavirus genus, are recently emerged, highly lethal zoonotic pathogens that cause yearly outbreaks. NiV and HeV each encode a W protein that has roles in regulating host signaling pathways, including antagonism of the innate immune response. However, the mechanisms used by W to regulate these host responses are not clear. Here, characterization of the interaction of NiV and HeV W with 14-3-3 identifies modulation of 14-3-3-regulated host signaling pathways not previously associated with W, suggesting new avenues of research. The cocrystal structure of the NiV W:14-3-3 complex, as only the second structure of a 14-3-3 mode III interactor, provides further insight into this less-well-understood 14-3-3 binding motif.
Collapse
Affiliation(s)
- Megan R Edwards
- Center for Microbial Pathogenesis, Institute for Biomedical Sciences, Georgia State University, Atlanta, Georgia, USA
| | - Mikayla Hoad
- School of Biomedical Sciences, Charles Sturt University, Wagga Wagga, NSW, Australia
| | - Sofiya Tsimbalyuk
- School of Biomedical Sciences, Charles Sturt University, Wagga Wagga, NSW, Australia
| | - Andrea R Menicucci
- Department of Molecular Biology and Biochemistry, College of Biological Sciences, University of California, Irvine, Irvine, California, USA
| | - Ilhem Messaoudi
- Department of Molecular Biology and Biochemistry, College of Biological Sciences, University of California, Irvine, Irvine, California, USA
| | - Jade K Forwood
- School of Biomedical Sciences, Charles Sturt University, Wagga Wagga, NSW, Australia
| | - Christopher F Basler
- Center for Microbial Pathogenesis, Institute for Biomedical Sciences, Georgia State University, Atlanta, Georgia, USA
| |
Collapse
|
7
|
Differential Subcellular Distribution and Translocation of Seven 14-3-3 Isoforms in Response to EGF and During the Cell Cycle. Int J Mol Sci 2020; 21:ijms21010318. [PMID: 31906564 PMCID: PMC6981507 DOI: 10.3390/ijms21010318] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 12/05/2019] [Accepted: 12/28/2019] [Indexed: 12/12/2022] Open
Abstract
Multiple isoforms of 14-3-3 proteins exist in different organisms. In mammalian cells, 14-3-3 protein has seven isoforms (α/β, ε, η, γ, σ, θ/τ, and δ/ζ), with α and δ representing the phosphorylated versions of β and ζ, respectively. While the existence of multiple isoforms may represent one more level of regulation in 14-3-3 signaling, our knowledge regarding the isoform-specific functions of 14-3-3 proteins is very limited. Determination of the subcellular localization of the different 14-3-3 isoforms could give us important clues of their specific functions. In this study, by using indirect immunofluorescence, subcellular fractionation, and immunoblotting, we studied the subcellular localization of the total 14-3-3 protein and each of the seven 14-3-3 isoforms; their redistribution throughout the cell cycle; and their translocation in response to EGF in Cos-7 cells. We showed that 14-3-3 proteins are broadly distributed throughout the cell and associated with many subcellular structures/organelles, including the plasma membrane (PM), mitochondria, ER, nucleus, microtubules, and actin fibers. This broad distribution underlines the multiple functions identified for 14-3-3 proteins. The different isoforms of 14-3-3 proteins have distinctive subcellular localizations, which suggest their distinctive cellular functions. Most notably, 14-3-3ƞ is almost exclusively localized to the mitochondria, 14-3-3γ is only localized to the nucleus, and 14-3-3σ strongly and specifically associated with the centrosome during mitosis. We also examined the subcellular localization of the seven 14-3-3 isoforms in other cells, including HEK-293, MDA-MB-231, and MCF-7 cells, which largely confirmed our findings with Cos-7 cells.
Collapse
|
8
|
Abdrabou A, Brandwein D, Liu C, Wang Z. Rac1 S71 Mediates the Interaction between Rac1 and 14-3-3 Proteins. Cells 2019; 8:E1006. [PMID: 31480268 PMCID: PMC6770128 DOI: 10.3390/cells8091006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 08/23/2019] [Accepted: 08/26/2019] [Indexed: 02/07/2023] Open
Abstract
Both 14-3-3 proteins (14-3-3s) and Rho proteins regulate cytoskeleton remodeling and cell migration, which suggests a possible interaction between the signaling pathways regulated by these two groups of proteins. Indeed, more and more emerging evidence indicates the mutual regulation of these two signaling pathways. However, all of the data regarding the interaction between Rac1 signaling pathways and 14-3-3 signaling pathways are through either the upstream regulators or downstream substrates. It is not clear if Rac1 could interact with 14-3-3s directly. It is interesting to notice that the Rac1 sequence 68RPLSYP73 is likely a 14-3-3 protein binding motif following the phosphorylation of S71 by Akt. Thus, we hypothesize that Rac1 directly interacts with 14-3-3s. We tested this hypothesis in this research. By using mutagenesis, co-immunoprecipitation (co-IP), Rac1 activity assay, immunoblotting, and indirect immunofluorescence, we demonstrate that 14-3-3s interact with Rac1. This interaction is mediated by Rac1 S71 in both phosphorylation-dependent and -independent manners, but the phosphorylation-dependent interaction is much stronger. Epidermal growth factor (EGF) strongly stimulates the phosphorylation of Rac1 S71 and the interaction between 14-3-3s and Rac1. Mutating S71 to A completely abolishes both phosphorylation-dependent and -independent interactions between 14-3-3s and Rac1. The interaction between 14-3-3s and Rac1 mostly serve to regulate the activity and subcellular localization of Rac1. Among the seven 14-3-3 isoforms, 14-3-3η, -σ, and -θ showed interactions with Rac1 in both Cos-7 and HEK 293 cells. 14-3-3γ also binds to Rac1 in HEK 293 cells, but not in Cos-7 cells. We conclude that 14-3-3s interact with Rac1. This interaction is mediated by Rac1 S71 in both phosphorylation-dependent and -independent manners. The interaction between 14-3-3 and Rac1 mostly serves to regulate the activity and subcellular localization of Rac1. Among the seven 14-3-3 isoforms, 14-3-3η, -γ, -σ, and -θ interact with Rac1.
Collapse
Affiliation(s)
- Abdalla Abdrabou
- Department of Medical Genetics, and Signal Transduction Research Group, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Daniel Brandwein
- Department of Medical Genetics, and Signal Transduction Research Group, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Changyu Liu
- Department of Medical Genetics, and Signal Transduction Research Group, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Zhixiang Wang
- Department of Medical Genetics, and Signal Transduction Research Group, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada.
| |
Collapse
|
9
|
Guevara J, Romo J, Hernandez E, Guevara NV. Identification of Receptor Ligands in Apo B100 Reveals Potential Functional Domains. Protein J 2019; 37:548-571. [PMID: 30259240 DOI: 10.1007/s10930-018-9792-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
LDL, VLDL and other members of the low-density lipoparticles (LLPs) enter cells through a large family of receptors. The actual receptor ligand(s) in apolipoprotein B100, one of the main proteins of LLP, remain(s) unknown. The objective of this study was to identify true receptor ligand(s) in apo B100, a molecule of 4563 residues. Apo B100 contains 33 analogues of Cardin-Weintraub arginine/lysine-based receptor ligand motifs and shares key lysine motifs and sequence similarity with the LDL receptor-associated protein, MESD, and heat shock proteins. Eleven FITC-labeled synthetic peptides of 21-42 residues, with at least one ligand, were tested for binding and internalization using HeLa cells. All peptides bind but display different binding capacities and patterns. Peptides B0013, B0582, B2366, and B2932 mediate endocytosis and appear in distinct sites in the cytoplasm. B0708 and B3181 bind and remain on the cell surface as aggregates/clusters. Peptides B3119 (Site A) and B3347 (Site B), the putative ligands, showed low binding and no cell entry capacity. Apo B100 regions in this study share similarities with related proteins of known function including chaperone proteins and Apo BEC stimulating protein, and not directly related proteins, e.g., the DNA-binding domain of interferon regulatory factors, MSX2-interacting protein, and snake venom Zinc metalloproteinase-disintegrin-like proteins.
Collapse
Affiliation(s)
- Juan Guevara
- Biophysics Research Laboratory, Department of Physics and Astronomy, The University of Texas Rio Grande Valley, One West University Blvd, Brownsville, TX, 78520, USA
| | - Jamie Romo
- Biophysics Research Laboratory, Department of Physics and Astronomy, The University of Texas Rio Grande Valley, One West University Blvd, Brownsville, TX, 78520, USA
| | - Ernesto Hernandez
- Biophysics Research Laboratory, Department of Physics and Astronomy, The University of Texas Rio Grande Valley, One West University Blvd, Brownsville, TX, 78520, USA
| | - Natalia Valentinova Guevara
- Biophysics Research Laboratory, Department of Physics and Astronomy, The University of Texas Rio Grande Valley, One West University Blvd, Brownsville, TX, 78520, USA.
| |
Collapse
|
10
|
Mackie TD, Brodsky JL. Investigating Potassium Channels in Budding Yeast: A Genetic Sandbox. Genetics 2018; 209:637-650. [PMID: 29967058 PMCID: PMC6028241 DOI: 10.1534/genetics.118.301026] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Accepted: 05/15/2018] [Indexed: 12/26/2022] Open
Abstract
Like all species, the model eukaryote Saccharomyces cerevisiae, or Bakers' yeast, concentrates potassium in the cytosol as an electrogenic osmolyte and enzyme cofactor. Yeast are capable of robust growth on a wide variety of potassium concentrations, ranging from 10 µM to 2.5 M, due to the presence of a high-affinity potassium uptake system and a battery of cation exchange transporters. Genetic perturbation of either of these systems retards yeast growth on low or high potassium, respectively. However, these potassium-sensitized yeast are a powerful genetic tool, which has been leveraged for diverse studies. Notably, the potassium-sensitive cells can be transformed with plasmids encoding potassium channels from bacteria, plants, or mammals, and subsequent changes in growth rate have been found to correlate with the activity of the introduced potassium channel. Discoveries arising from the use of this assay over the past three decades have increased our understanding of the structure-function relationships of various potassium channels, the mechanisms underlying the regulation of potassium channel function and trafficking, and the chemical basis of potassium channel modulation. In this article, we provide an overview of the major genetic tools used to study potassium channels in S. cerevisiae, a survey of seminal studies utilizing these tools, and a prospective for the future use of this elegant genetic approach.
Collapse
Affiliation(s)
- Timothy D Mackie
- Department of Biological Sciences, University of Pittsburgh, Pennsylvania 15260
| | - Jeffrey L Brodsky
- Department of Biological Sciences, University of Pittsburgh, Pennsylvania 15260
| |
Collapse
|
11
|
Interaction between Rho GTPases and 14-3-3 Proteins. Int J Mol Sci 2017; 18:ijms18102148. [PMID: 29036929 PMCID: PMC5666830 DOI: 10.3390/ijms18102148] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 10/11/2017] [Accepted: 10/13/2017] [Indexed: 01/25/2023] Open
Abstract
The Rho GTPase family accounts for as many as 20 members. Among them, the archetypes RhoA, Rac1, and Cdc42 have been the most well-characterized. Like all members of the small GTPases superfamily, Rho proteins act as molecular switches to control cellular processes by cycling between active, GTP-bound and inactive, GDP-bound states. The 14-3-3 family proteins comprise seven isoforms. They exist as dimers (homo- or hetero-dimer) in cells. They function by binding to Ser/Thr phosphorylated intracellular proteins, which alters the conformation, activity, and subcellular localization of their binding partners. Both 14-3-3 proteins and Rho GTPases regulate cell cytoskeleton remodeling and cell migration, which suggests a possible interaction between the signaling pathways regulated by these two groups of proteins. Indeed, more and more emerging evidence indicates the mutual regulation of these two signaling pathways. There have been many documented reviews of 14-3-3 protein and Rac1 separately, but there is no review regarding the interaction and mutual regulation of these two groups of proteins. Thus, in this article we thoroughly review all the reported interactions between the signaling pathways regulated by 14-3-3 proteins and Rho GTPases (mostly Rac1).
Collapse
|
12
|
Yu J, Chen L, Chen Y, Hasan MK, Ghia EM, Zhang L, Wu R, Rassenti LZ, Widhopf GF, Shen Z, Briggs SP, Kipps TJ. Wnt5a induces ROR1 to associate with 14-3-3ζ for enhanced chemotaxis and proliferation of chronic lymphocytic leukemia cells. Leukemia 2017; 31:2608-2614. [PMID: 28465528 PMCID: PMC5670032 DOI: 10.1038/leu.2017.132] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 03/03/2017] [Accepted: 03/21/2017] [Indexed: 11/09/2022]
Abstract
Wnt5a can activate Rho GTPases in chronic lymphocytic leukemia (CLL) cells by inducing the recruitment of ARHGEF2 to ROR1. Mass spectrometry on immune precipitates of Wnt5a-activated ROR1 identified 14-3-3ζ, which was confirmed by co-immunoprecipitation. The capacity of Wnt5a to induce ROR1 to complex with 14-3-3ζ could be blocked in CLL cells by treatment with cirmtuzumab, a humanized mAb targeting ROR1. Silencing 14-3-3ζ via small interfering RNA impaired the capacity of Wnt5a to: (1) induce recruitment of ARHGEF2 to ROR1, (2) enhance in vitro exchange activity of ARHGEF2 and (3) induce activation of RhoA and Rac1 in CLL cells. Furthermore, CRISPR/Cas9 deletion of 14-3-3ζ in ROR1-negative CLL cell-line MEC1, and in MEC1 cells transfected to express ROR1 (MEC1-ROR1), demonstrated that 14-3-3ζ was necessary for the growth/engraftment advantage of MEC1-ROR1 over MEC1 cells. We identified a binding motif (RSPS857SAS) in ROR1 for 14-3-3ζ. Site-directed mutagenesis of ROR1 demonstrated that serine-857 was required for the recruitment of 14-3-3ζ and ARHGEF2 to ROR1, and activation of RhoA and Rac1. Collectively, this study reveals that 14-3-3ζ plays a critical role in Wnt5a/ROR1 signaling, leading to enhanced CLL migration and proliferation.
Collapse
Affiliation(s)
- J Yu
- Moores Cancer Center, University of California-San Diego, La Jolla, CA, USA
| | - L Chen
- Moores Cancer Center, University of California-San Diego, La Jolla, CA, USA
| | - Y Chen
- Moores Cancer Center, University of California-San Diego, La Jolla, CA, USA
| | - M K Hasan
- Moores Cancer Center, University of California-San Diego, La Jolla, CA, USA
| | - E M Ghia
- Moores Cancer Center, University of California-San Diego, La Jolla, CA, USA
| | - L Zhang
- Moores Cancer Center, University of California-San Diego, La Jolla, CA, USA
| | - R Wu
- Moores Cancer Center, University of California-San Diego, La Jolla, CA, USA
| | - L Z Rassenti
- Moores Cancer Center, University of California-San Diego, La Jolla, CA, USA
| | - G F Widhopf
- Moores Cancer Center, University of California-San Diego, La Jolla, CA, USA
| | - Z Shen
- Section of Cell and Developmental Biology, University of California-San Diego, La Jolla, CA, USA
| | - S P Briggs
- Section of Cell and Developmental Biology, University of California-San Diego, La Jolla, CA, USA
| | - T J Kipps
- Moores Cancer Center, University of California-San Diego, La Jolla, CA, USA
| |
Collapse
|
13
|
Fernández-Orth J, Ehling P, Ruck T, Pankratz S, Hofmann MS, Landgraf P, Dieterich DC, Smalla KH, Kähne T, Seebohm G, Budde T, Wiendl H, Bittner S, Meuth SG. 14-3-3 Proteins regulate K 2P 5.1 surface expression on T lymphocytes. Traffic 2016; 18:29-43. [PMID: 27743426 DOI: 10.1111/tra.12455] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 10/12/2016] [Accepted: 10/12/2016] [Indexed: 01/10/2023]
Abstract
K2P 5.1 channels (also called TASK-2 or Kcnk5) have already been shown to be relevant in the pathophysiology of autoimmune disease because they are known to be upregulated on peripheral and central T lymphocytes of multiple sclerosis (MS) patients. Moreover, overexpression of K2P 5.1 channels in vitro provokes enhanced T-cell effector functions. However, the molecular mechanisms regulating intracellular K2P 5.1 channel trafficking are unknown so far. Thus, the aim of the study is to elucidate the trafficking of K2P 5.1 channels on T lymphocytes. Using mass spectrometry analysis, we have identified 14-3-3 proteins as novel binding partners of K2P 5.1 channels. We show that a non-classical 14-3-3 consensus motif (R-X-X-pT/S-x) at the channel's C-terminus allows the binding between K2P 5.1 and 14-3-3. The mutant K2P 5.1/S266A diminishes the protein-protein interaction and reduces the amplitude of membrane currents. Application of a non-peptidic 14-3-3 inhibitor (BV02) significantly reduces the number of wild-type channels in the plasma membrane, whereas the drug has no effect on the trafficking of the mutated channel. Furthermore, blocker application reduces T-cell effector functions. Taken together, we demonstrate that 14-3-3 interacts with K2P 5.1 and plays an important role in channel trafficking.
Collapse
Affiliation(s)
| | - Petra Ehling
- Department of Neurology, Westfälische Wilhelms-Universität, Münster, Germany
| | - Tobias Ruck
- Department of Neurology, Westfälische Wilhelms-Universität, Münster, Germany
| | - Susann Pankratz
- Department of Neurology, Westfälische Wilhelms-Universität, Münster, Germany
| | | | - Peter Landgraf
- Neural Plasticity and Communication, Institute for Pharmacology and Toxicology, Otto von-Guericke-University, Magdeburg, Germany
| | - Daniela C Dieterich
- Neural Plasticity and Communication, Institute for Pharmacology and Toxicology, Otto von-Guericke-University, Magdeburg, Germany.,Center for Behavioral Brain Sciences (CBBS), Otto von-Guericke-University, Magdeburg, Germany
| | - Karl-Heinz Smalla
- Special Lab Molecular Biological Techniques, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Thilo Kähne
- Institute of Experimental Internal Medicine, Medical Faculty, Otto-von-Guericke-University, Magdeburg, Germany
| | - Guiscard Seebohm
- Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases (IfGH), University Hospital Münster, Münster, Germany
| | - Thomas Budde
- Institute for Physiology I, Westfälische Wilhelms-Universität, Münster, Germany
| | - Heinz Wiendl
- Department of Neurology, Westfälische Wilhelms-Universität, Münster, Germany
| | - Stefan Bittner
- Department of Neurology, University Medical Center, Johannes Gutenberg-University, Mainz, Germany
| | - Sven G Meuth
- Department of Neurology, Westfälische Wilhelms-Universität, Münster, Germany
| |
Collapse
|
14
|
The role of protein-protein interactions in the intracellular traffic of the potassium channels TASK-1 and TASK-3. Pflugers Arch 2015; 467:1105-20. [PMID: 25559843 DOI: 10.1007/s00424-014-1672-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Revised: 12/10/2014] [Accepted: 12/11/2014] [Indexed: 10/24/2022]
Abstract
The intracellular transport of membrane proteins is controlled by trafficking signals: Short peptide motifs that mediate the contact with COPI, COPII or various clathrin-associated coat proteins. In addition, many membrane proteins interact with accessory proteins that are involved in the sorting of these proteins to different intracellular compartments. In the K2P channels, TASK-1 and TASK-3, the influence of protein-protein interactions on sorting decisions has been studied in some detail. Both TASK paralogues interact with the adaptor protein 14-3-3; TASK-1 interacts, in addition, with the adaptor protein p11 (S100A10) and the endosomal SNARE protein syntaxin-8. The role of these interacting proteins in controlling the intracellular traffic of the channels and the underlying molecular mechanisms are summarised in this review. In the case of 14-3-3, the interacting protein masks a retention signal in the C-terminus of the channel; in the case of p11, the interacting protein carries a retention signal that localises the channel to the endoplasmic reticulum; and in the case of syntaxin-8, the interacting protein carries an endocytosis signal that complements an endocytosis signal of the channel. These examples illustrate some of the mechanisms by which interacting proteins may determine the itinerary of a membrane protein within a cell and suggest that the intracellular traffic of membrane proteins may be adapted to the specific functions of that protein by multiple protein-protein interactions.
Collapse
|
15
|
Bagriantsev SN, Chatelain FC, Clark KA, Alagem N, Reuveny E, Minor DL. Tethered protein display identifies a novel Kir3.2 (GIRK2) regulator from protein scaffold libraries. ACS Chem Neurosci 2014; 5:812-22. [PMID: 25028803 PMCID: PMC4176385 DOI: 10.1021/cn5000698] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
![]()
Use of randomized peptide libraries
to evolve molecules with new
functions provides a means for developing novel regulators of protein
activity. Despite the demonstrated power of such approaches for soluble
targets, application of this strategy to membrane systems, such as
ion channels, remains challenging. Here, we have combined libraries
of a tethered protein scaffold with functional selection in yeast
to develop a novel activator of the G-protein-coupled mammalian inwardly
rectifying potassium channel Kir3.2 (GIRK2). We show that the novel
regulator, denoted N5, increases Kir3.2 (GIRK2) basal activity by
inhibiting clearance of the channel from the cellular surface rather
than affecting the core biophysical properties of the channel. These
studies establish the tethered protein display strategy as a means
to create new channel modulators and highlight the power of approaches
that couple randomized libraries with direct selections for functional
effects. Our results further underscore the possibility for the development
of modulators that influence channel function by altering cell surface
expression densities rather than by direct action on channel biophysical
parameters. The use of tethered library selection strategies coupled
with functional selection bypasses the need for a purified target
and is likely to be applicable to a range of membrane protein systems.
Collapse
Affiliation(s)
| | | | | | - Noga Alagem
- Department
of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Eitan Reuveny
- Department
of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Daniel L. Minor
- Physical
Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| |
Collapse
|
16
|
Arakel EC, Brandenburg S, Uchida K, Zhang H, Lin YW, Kohl T, Schrul B, Sulkin MS, Efimov IR, Nichols CG, Lehnart SE, Schwappach B. Tuning the electrical properties of the heart by differential trafficking of KATP ion channel complexes. J Cell Sci 2014; 127:2106-19. [PMID: 24569881 PMCID: PMC4004980 DOI: 10.1242/jcs.141440] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The copy number of membrane proteins at the cell surface is tightly regulated. Many ion channels and receptors present retrieval motifs to COPI vesicle coats and are retained in the early secretory pathway. In some cases, the interaction with COPI is prevented by binding to 14-3-3 proteins. However, the functional significance of this antagonism between COPI and 14-3-3 in terminally differentiated cells is unknown. Here, we show that ATP-sensitive K+ (KATP) channels, which are composed of Kir6.2 and SUR1 subunits, are stalled in the Golgi complex of ventricular, but not atrial, cardiomyocytes. Upon sustained β-adrenergic stimulation, which leads to activation of protein kinase A (PKA), SUR1-containing channels reach the plasma membrane of ventricular cells. We show that PKA-dependent phosphorylation of the C-terminus of Kir6.2 decreases binding to COPI and, thereby, silences the arginine-based retrieval signal. Thus, activation of the sympathetic nervous system releases this population of KATP channels from storage in the Golgi and, hence, might facilitate the adaptive response to metabolic challenges.
Collapse
Affiliation(s)
- Eric C Arakel
- Department of Molecular Biology, Center for Biochemistry and Molecular Cell Biology, Heart Research Center Göttingen, University Medicine Göttingen, Humboldtallee 23, 37073 Göttingen, Germany
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Batra N, Riquelme MA, Burra S, Jiang JX. 14-3-3θ facilitates plasma membrane delivery and function of mechanosensitive connexin 43 hemichannels. J Cell Sci 2013; 127:137-46. [PMID: 24163432 DOI: 10.1242/jcs.133553] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Intracellular signaling in osteocytes activated by mechanical loading is important for bone formation and remodeling. These signaling events are mediated by small modulators released from Cx43 hemichannels (HC). We have recently shown that integrin α5 senses the mechanical stimulation and induces the opening of Cx43 HC; however, the underlying mechanism is unknown. Here, we show that both Cx43 and integrin α5 interact with 14-3-3θ, and this interaction is required for the opening of Cx43 HC upon mechanical stress. The absence of 14-3-3θ prevented the interaction between Cx43 and integrin α5, and blocked HC opening. Furthermore, it decreased the transport of Cx43 and integrin α5 from the Golgi apparatus to the plasma membrane. Mechanical loading promoted the movement of Cx43 to the surface which was associated not only with an increase in 14-3-3θ levels but also its interaction with Cx43 and integrin α5. This stimulatory effect on forward transport by mechanical loading was attenuated in the absence of 14-3-3θ and the majority of the Cx43 accumulated in the Golgi. Disruption of the Golgi by brefeldin A reduced the association of Cx43 and integrin α5 with 14-3-3θ, further suggesting that the interaction is likely to occur in the Golgi. Together, these results define a previously unidentified, scaffolding role of 14-3-3θ in assisting the delivery of Cx43 and integrin α5 to the plasma membrane for the formation of mechanosensitive HC in osteocytes.
Collapse
Affiliation(s)
- Nidhi Batra
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA
| | | | | | | |
Collapse
|
18
|
Potential use of potassium efflux-deficient yeast for studying trafficking signals and potassium channel functions. FEBS Open Bio 2013; 3:196-203. [PMID: 23772394 PMCID: PMC3668539 DOI: 10.1016/j.fob.2013.04.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 04/02/2013] [Accepted: 04/11/2013] [Indexed: 11/22/2022] Open
Abstract
The activity of potassium (K(+)) channels critically depends on their density on the cell surface membrane, which is regulated by dynamic protein-protein interactions that often involve distinct trafficking signals on the cargo proteins. In this paper we explored the possibility of utilizing the Saccharomyces cerevisiae strain B31 for identification of the signal motifs that regulate surface expression of membrane proteins and for studying structure-function relationships of K(+) channels. B31 cells lack the K(+) efflux system and were reported to show overloaded K(+)-mediated growth inhibition in high K(+) media upon heterologous expression of a mammalian inwardly rectifying K(+) channel (Kir2.1). We show that while the expression of wild-type Kir2.1 channel inhibits the growth of B31 cells in high K(+) media, the human disease-causing mutations of Kir2.1 that abolish K(+) conduction (V302M) or surface trafficking (Δ314/315) fully restores the growth. The expression of two-pore-domain K(+) channel KCNK3 or KCNK9 also inhibited the growth of B31 in high K(+) media while C-terminal mutations that reduce their 14-3-3 protein-dependent cell surface trafficking restored the growth of B31. Finally, the expression of Kir2.1 channels that were C-terminally fused with known sequence motifs including ER retention/retrieval signals and an endocytosis signal allowed the growth of B31 in high K(+) media. These results demonstrate the potential of B31 yeast strain as a unique biological tool to screen the random peptide libraries for novel sequence signals that down-regulate surface expression of membrane proteins, as well as to systematically identify the structural determinants for cell surface trafficking and/or ion conductance of K(+) channels.
Collapse
|
19
|
Camoni L, Visconti S, Aducci P. The phytotoxin fusicoccin, a selective stabilizer of 14-3-3 interactions? IUBMB Life 2013; 65:513-7. [DOI: 10.1002/iub.1167] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 02/28/2013] [Indexed: 11/10/2022]
|
20
|
Anders C, Higuchi Y, Koschinsky K, Bartel M, Schumacher B, Thiel P, Nitta H, Preisig-Müller R, Schlichthörl G, Renigunta V, Ohkanda J, Daut J, Kato N, Ottmann C. A Semisynthetic Fusicoccane Stabilizes a Protein-Protein Interaction and Enhances the Expression of K+ Channels at the Cell Surface. ACTA ACUST UNITED AC 2013; 20:583-93. [DOI: 10.1016/j.chembiol.2013.03.015] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Revised: 03/21/2013] [Accepted: 03/25/2013] [Indexed: 01/01/2023]
|
21
|
Li JG, Chen C, Huang P, Wang Y, Liu-Chen LY. 14-3-3ζ Protein regulates anterograde transport of the human κ-opioid receptor (hKOPR). J Biol Chem 2012; 287:37778-92. [PMID: 22989890 DOI: 10.1074/jbc.m112.359679] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
By proteomic analysis, we found that 14-3-3ζ was one of the proteins co-immunoprecipitated with human κ-opioid receptor (hKOPR) from extracts of solubilized Neuro2A cells stably expressing FLAG-hKOPR (N2A-FLAG-hKOPR cells). 14-3-3 proteins are a family of conserved regulatory molecules in eukaryotic cells, where they participate in signal transduction, metabolism, and membrane protein transport. 14-3-3ζ co-localized with the hKOPR in N2A cells. The hKOPR C-tail interacted with 14-3-3ζ in rat brain extracts and bound directly to purified 14-3-3ζ as demonstrated by pulldown techniques. 14-3-3ζ siRNA decreased expression of the hKOPR in N2A-FLAG-hKOPR cells and cultured primary cortical neurons of E19 rats by ~25% as determined by immunoblotting, ligand binding, and flow cytometry. The effect of 14-3-3ζ siRNA was reversed by overexpression of 14-3-3ζ. Expression of the 14-3-3 scavenger protein pGpLI-R18 also decreased hKOPR expression. 14-3-3ζ siRNA did not change expressions of the hDOPR and rMOPR in N2A cells. Pulse-chase study showed that 14-3-3ζ siRNA decreased the amount of mature hKOPR but did not change the rate of maturation or stability of hKOPR protein. Mutations of R354A/S358A in the putative 14-3-3 interaction motif (354)RQSTS(358) in the hKOPR C-tail reduced interaction of the hKOPR with 14-3-3ζ and abolished the effect of 14-3-3ζ knockdown on hKOPR expression. Mutation of the endoplasmic reticulum retention motif (359)RVR adjacent to the 14-3-3 interaction motif in the hKOPR C-tail decreased interaction of coatomer protein I (COPI) with the hKOPR and abolished 14-3-3ζ-mediated regulation of hKOPR expression. 14-3-3ζ knockdown increased association of COPI with the hKOPR. These results suggest that 14-3-3ζ promotes expression of the hKOPR by inhibiting COPI and RVR motif-mediated endoplasmic reticulum localization machinery.
Collapse
Affiliation(s)
- Jian-Guo Li
- Department of Pharmacology and Center for Substance Abuse Research, Temple University School of Medicine, Philadelphia, Pennsylvania 19140, USA
| | | | | | | | | |
Collapse
|
22
|
Morales D, Skoulakis ECM, Acevedo SF. 14-3-3s are potential biomarkers for HIV-related neurodegeneration. J Neurovirol 2012; 18:341-53. [PMID: 22811265 DOI: 10.1007/s13365-012-0121-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Revised: 06/06/2012] [Accepted: 06/27/2012] [Indexed: 02/07/2023]
Abstract
Over the last decade, it has become evident that 14-3-3 proteins are essential for primary cell functions. These proteins are abundant throughout the body, including the central nervous system and interact with other proteins in both cell cycle and apoptotic pathways. Examination of cerebral spinal fluid in humans suggests that 14-3-3s including 14-3-3ε (YWHAE) are up-regulated in several neurological diseases, and loss or duplication of the YWHAE gene leads to Miller-Dieker syndrome. The goal of this review is to examine the utility of 14-3-3s as a marker of human immune deficiency virus (HIV)-dependent neurodegeneration and also as a tool to track disease progression. To that end, we describe mechanisms implicating 14-3-3s in neurological diseases and summarize evidence of its interactions with HIV accessory and co-receptor proteins.
Collapse
Affiliation(s)
- Diana Morales
- Department of Physiology, Pharmacology, and Toxicology, Ponce School of Medicine and Health Sciences, Ponce 00732, Puerto Rico
| | | | | |
Collapse
|
23
|
de Boer AH, de Vries-van Leeuwen IJ. Fusicoccanes: diterpenes with surprising biological functions. TRENDS IN PLANT SCIENCE 2012; 17:360-8. [PMID: 22465041 DOI: 10.1016/j.tplants.2012.02.007] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Revised: 02/14/2012] [Accepted: 02/20/2012] [Indexed: 05/25/2023]
Abstract
Fusicoccin is the best-studied member of a class of diterpenes sharing a 5-8-5 ring structure, called fusicoccanes. Fusicoccin was and still is a 'tool in plant physiology', targeting the main engine of plasma membrane transport, the P-type H(+)-ATPase, assisted by members of the 14-3-3 family. The key position of 14-3-3 proteins in cell biology, combined with a broader specificity of other fusicoccanes as shown by crystallography studies, make fusicoccanes a versatile tool in plant and animal biology. In this review, we examine recent evidence that fusicoccanes act on animal cells, describe the discovery of the fungal biosynthetic pathway and emphasize that lower (liverworts) and higher plants produce fusicoccanes with intriguing biological activities.
Collapse
Affiliation(s)
- Albertus H de Boer
- Department of Structural Biology, Faculty of Earth and Life Sciences, Vrije Universiteit, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands.
| | | |
Collapse
|
24
|
Lalle M, Camerini S, Cecchetti S, Sayadi A, Crescenzi M, Pozio E. Interaction Network of the 14-3-3 Protein in the Ancient Protozoan Parasite Giardia duodenalis. J Proteome Res 2012; 11:2666-83. [DOI: 10.1021/pr3000199] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Marco Lalle
- Department of Infectious, Parasitic
and Immunomediated Diseases, Istituto Superiore di Sanità, 00161 Rome, Italy
| | - Serena Camerini
- Department
of Cell Biology and
Neurosciences, Istituto Superiore di Sanità, 00161 Rome, Italy
| | - Serena Cecchetti
- Department
of Cell Biology and
Neurosciences, Istituto Superiore di Sanità, 00161 Rome, Italy
| | - Ahmed Sayadi
- Department
of Biochemical Sciences
“A. Rossi-Fanelli”, University of Rome “Sapienza”, 00185 Rome, Italy
| | - Marco Crescenzi
- Department
of Cell Biology and
Neurosciences, Istituto Superiore di Sanità, 00161 Rome, Italy
| | - Edoardo Pozio
- Department of Infectious, Parasitic
and Immunomediated Diseases, Istituto Superiore di Sanità, 00161 Rome, Italy
| |
Collapse
|
25
|
Smith AJ, Daut J, Schwappach B. Membrane proteins as 14-3-3 clients in functional regulation and intracellular transport. Physiology (Bethesda) 2011; 26:181-91. [PMID: 21670164 DOI: 10.1152/physiol.00042.2010] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
14-3-3 proteins regulate the function and subcellular sorting of membrane proteins. Often, 14-3-3 binding to client proteins requires phosphorylation of the client, but the relevant kinase is unknown in most cases. We summarize current progress in identifying kinases that target membrane proteins with 14-3-3 binding sites and discuss the molecular mechanisms of 14-3-3 action. One of the kinases involved is Akt/PKB, which has recently been shown to activate the 14-3-3-dependent switch in a number of client membrane proteins.
Collapse
Affiliation(s)
- Andrew J Smith
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
| | | | | |
Collapse
|
26
|
Shandala T, Woodcock JM, Ng Y, Biggs L, Skoulakis EMC, Brooks DA, Lopez AF. Drosophila 14-3-3ε has a crucial role in anti-microbial peptide secretion and innate immunity. J Cell Sci 2011; 124:2165-74. [DOI: 10.1242/jcs.080598] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The secretion of anti-microbial peptides is recognised as an essential step in innate immunity, but there is limited knowledge of the molecular mechanism controlling the release of these effectors from immune response cells. Here, we report that Drosophila 14-3-3ε mutants exhibit reduced survival when infected with either Gram-positive or Gram-negative bacteria, indicating a functional role for 14-3-3ε in innate immunity. In 14-3-3ε mutants, there was a reduced release of the anti-microbial peptide Drosomycin into the haemolymph, which correlated with an accumulation of Drosomycin-containing vesicles near the plasma membrane of cells isolated from immune response tissues. Drosomycin appeared to be delivered towards the plasma membrane in Rab4- and Rab11-positive vesicles and smaller Rab11-positive vesicles. RNAi silencing of Rab11 and Rab4 significantly blocked the anterograde delivery of Drosomycin from the perinuclear region to the plasma membrane. However, in 14-3-3ε mutants there was an accumulation of small Rab11-positive vesicles near the plasma membrane. This vesicular phenotype was similar to that observed in response to the depletion of the vesicular Syntaxin protein Syx1a. In wild-type Drosophila immune tissue, 14-3-3ε was detected adjacent to Rab11, and partially overlapping with Syx1a, on vesicles near the plasma membrane. We conclude that 14-3-3ε is required for Rab11-positive vesicle function, which in turn enables antimicrobial peptide secretion during an innate immune response.
Collapse
Affiliation(s)
- Tetyana Shandala
- Division of Human Immunology, Centre for Cancer Biology, Adelaide SA5000, Australia
- Sansom Institute for Health Research, University of South Australia, Adelaide SA5000, Australia
- School of Molecular and Biomedical Science, University of Adelaide, Adelaide SA5000, Australia
| | - Joanna M. Woodcock
- Division of Human Immunology, Centre for Cancer Biology, Adelaide SA5000, Australia
| | - Yeap Ng
- Division of Human Immunology, Centre for Cancer Biology, Adelaide SA5000, Australia
- Sansom Institute for Health Research, University of South Australia, Adelaide SA5000, Australia
| | - Lisa Biggs
- Division of Human Immunology, Centre for Cancer Biology, Adelaide SA5000, Australia
| | | | - Doug A. Brooks
- Sansom Institute for Health Research, University of South Australia, Adelaide SA5000, Australia
- School of Molecular and Biomedical Science, University of Adelaide, Adelaide SA5000, Australia
| | - Angel F. Lopez
- Division of Human Immunology, Centre for Cancer Biology, Adelaide SA5000, Australia
| |
Collapse
|
27
|
Isayenkov S, Isner JC, Maathuis FJ. Rice two-pore K+ channels are expressed in different types of vacuoles. THE PLANT CELL 2011; 23:756-68. [PMID: 21224427 PMCID: PMC3077780 DOI: 10.1105/tpc.110.081463] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Revised: 11/30/2010] [Accepted: 12/17/2010] [Indexed: 05/17/2023]
Abstract
Potassium (K+) is a major nutrient for plant growth and development. Vacuolar K+ ion channels of the two-pore K+ (TPK) family play an important role in maintaining K+ homeostasis. Several TPK channels were previously shown to be expressed in the lytic vacuole (LV) tonoplast. Plants also contain smaller protein storage vacuoles (PSVs) that contain membrane transporters. However, the mechanisms that define how membrane proteins reach different vacuolar destinations are largely unknown. The Oryza sativa genome encodes two TPK isoforms (TPKa and TPKb) that have very similar sequences and are ubiquitously expressed. The electrophysiological properties of both TPKs were comparable, showing inward rectification and voltage independence. In spite of high levels of similarity in sequence and transport properties, the cellular localization of TPKa and TPKb channels was different, with TPKa localization predominantly at the large LV and TPKb primarily in smaller PSV-type compartments. Trafficking of TPKa was sensitive to brefeldin A, while that of TPKb was not. The use of TPKa:TPKb chimeras showed that C-terminal domains are crucial for the differential targeting of TPKa and TPKb. Site-directed mutagenesis of C-terminal residues that were different between TPKa and TPKb identified three amino acids that are important in determining ultimate vacuolar destination.
Collapse
Affiliation(s)
| | | | - Frans J.M. Maathuis
- University of York, Biology Department/Area 9, York YO10 5DD, United Kingdom
| |
Collapse
|
28
|
Plant Proton Pumps: Regulatory Circuits Involving H+-ATPase and H+-PPase. SIGNALING AND COMMUNICATION IN PLANTS 2011. [DOI: 10.1007/978-3-642-14369-4_2] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
|
29
|
Okamoto Y, Shikano S. Phosphorylation-dependent C-terminal binding of 14-3-3 proteins promotes cell surface expression of HIV co-receptor GPR15. J Biol Chem 2010; 286:7171-81. [PMID: 21189250 DOI: 10.1074/jbc.m110.199695] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Membrane trafficking is dictated by dynamic molecular interactions involving discrete determinants in the cargo proteins and the intracellular transport machineries. We have previously reported that cell surface expression of GPR15, a G protein-coupled receptor (GPCR) that serves as a co-receptor for HIV, is correlated with the mode III binding of 14-3-3 proteins to the receptor C terminus. Here we provide a mechanistic basis for the role of 14-3-3 in promoting the cell surface expression of GPR15. The Ala mutation of penultimate phospho-Ser (S359A) that abolishes 14-3-3 binding resulted in substantially reduced O-glycosylation and the cell surface expression of GPR15. The surface membrane protein CD8 fused with the C-terminal tail of GPR15(S359A) mutant was re-localized in the endoplasmic reticulum (ER). In the context of S359A mutation, the additional mutations in the upstream stretch of basic residues (RXR motif) restored O-glycosylation and the cell surface expression. The RXR motif was responsible for the interaction with coatomer protein I (COPI), which was inversely correlated with the 14-3-3 binding and cell surface expression. These results suggest that 14-3-3 binding promotes cell surface expression of GPR15 by releasing the receptor from ER retrieval/retention pathway that is mediated by the interaction of RXR motif and COPI. Moreover, 14-3-3 binding substantially increased the stability of GPR15 protein. Thus 14-3-3 proteins play multiple roles in biogenesis and trafficking of an HIV co-receptor GPR15 to control its cell surface density in response to the phosphorylation signal.
Collapse
Affiliation(s)
- Yukari Okamoto
- Department of Biochemistry and Molecular Genetics, University of Illinois, Chicago, Illinois 60607, USA
| | | |
Collapse
|
30
|
Ramser EM, Wolters G, Dityateva G, Dityatev A, Schachner M, Tilling T. The 14-3-3ζ protein binds to the cell adhesion molecule L1, promotes L1 phosphorylation by CKII and influences L1-dependent neurite outgrowth. PLoS One 2010; 5:e13462. [PMID: 20976158 PMCID: PMC2956685 DOI: 10.1371/journal.pone.0013462] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2010] [Accepted: 09/24/2010] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND The cell adhesion molecule L1 is crucial for mammalian nervous system development. L1 acts as a mediator of signaling events through its intracellular domain, which comprises a putative binding site for 14-3-3 proteins. These regulators of diverse cellular processes are abundant in the brain and preferentially expressed by neurons. In this study, we investigated whether L1 interacts with 14-3-3 proteins, how this interaction is mediated, and whether 14-3-3 proteins influence the function of L1. METHODOLOGY/PRINCIPAL FINDINGS By immunoprecipitation, we demonstrated that 14-3-3 proteins are associated with L1 in mouse brain. The site of 14-3-3 interaction in the L1 intracellular domain (L1ICD), which was identified by site-directed mutagenesis and direct binding assays, is phosphorylated by casein kinase II (CKII), and CKII phosphorylation of the L1ICD enhances binding of the 14-3-3 zeta isoform (14-3-3ζ). Interestingly, in an in vitro phosphorylation assay, 14-3-3ζ promoted CKII-dependent phosphorylation of the L1ICD. Given that L1 phosphorylation by CKII has been implicated in L1-triggered axonal elongation, we investigated the influence of 14-3-3ζ on L1-dependent neurite outgrowth. We found that expression of a mutated form of 14-3-3ζ, which impairs interactions of 14-3-3ζ with its binding partners, stimulated neurite elongation from cultured rat hippocampal neurons, supporting a functional connection between L1 and 14-3-3ζ. CONCLUSIONS/SIGNIFICANCE Our results suggest that 14-3-3ζ, a novel direct binding partner of the L1ICD, promotes L1 phosphorylation by CKII in the central nervous system, and regulates neurite outgrowth, an important biological process triggered by L1.
Collapse
Affiliation(s)
- Elisa M. Ramser
- Zentrum für Molekulare Neurobiologie Hamburg, University of Hamburg, Hamburg, Germany
| | - Gerrit Wolters
- Zentrum für Molekulare Neurobiologie Hamburg, University of Hamburg, Hamburg, Germany
| | - Galina Dityateva
- Zentrum für Molekulare Neurobiologie Hamburg, University of Hamburg, Hamburg, Germany
- Department of Neuroscience and Brain Technologies, Italian Institute of Technology, Genova, Italy
| | - Alexander Dityatev
- Zentrum für Molekulare Neurobiologie Hamburg, University of Hamburg, Hamburg, Germany
- Department of Neuroscience and Brain Technologies, Italian Institute of Technology, Genova, Italy
| | - Melitta Schachner
- Zentrum für Molekulare Neurobiologie Hamburg, University of Hamburg, Hamburg, Germany
- Keck Center for Collaborative Neuroscience and Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey, United States of America
| | - Thomas Tilling
- Zentrum für Molekulare Neurobiologie Hamburg, University of Hamburg, Hamburg, Germany
| |
Collapse
|
31
|
Mathie A, Rees KA, El Hachmane MF, Veale EL. Trafficking of neuronal two pore domain potassium channels. Curr Neuropharmacol 2010; 8:276-86. [PMID: 21358977 PMCID: PMC3001220 DOI: 10.2174/157015910792246146] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2009] [Revised: 01/18/2010] [Accepted: 01/18/2010] [Indexed: 01/05/2023] Open
Abstract
The activity of two pore domain potassium (K2P) channels regulates neuronal excitability and cell firing. Post-translational regulation of K2P channel trafficking to the membrane controls the number of functional channels at the neuronal membrane affecting the functional properties of neurons. In this review, we describe the general features of K channel trafficking from the endoplasmic reticulum (ER) to the plasma membrane via the Golgi apparatus then focus on established regulatory mechanisms for K2P channel trafficking. We describe the regulation of trafficking of TASK channels from the ER or their retention within the ER and consider the competing hypotheses for the roles of the chaperone proteins 14-3-3, COP1 and p11 in these processes and where these proteins bind to TASK channels. We also describe the localisation of TREK channels to particular regions of the neuronal membrane and the involvement of the TREK channel binding partners AKAP150 and Mtap2 in this localisation. We describe the roles of other K2P channel binding partners including Arf6, EFA6 and SUMO for TWIK1 channels and Vpu for TASK1 channels. Finally, we consider the potential importance of K2P channel trafficking in a number of disease states such as neuropathic pain and cancer and the protection of neurons from ischemic damage. We suggest that a better understanding of the mechanisms and regulations that underpin the trafficking of K2P channels to the plasma membrane and to localised regions therein may considerably enhance the probability of future therapeutic advances in these areas.
Collapse
Affiliation(s)
- Alistair Mathie
- Medway School of Pharmacy, Universities of Kent and Greenwich at Medway, Central Avenue, Chatham Maritime, Kent ME4 4TB, UK
| | | | | | | |
Collapse
|
32
|
|
33
|
Veale EL, Rees KA, Mathie A, Trapp S. Dominant negative effects of a non-conducting TREK1 splice variant expressed in brain. J Biol Chem 2010; 285:29295-304. [PMID: 20605797 DOI: 10.1074/jbc.m110.108423] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Two-pore domain potassium (K(2P)) channels modulate neuronal excitability throughout the entire CNS. The stretch-activated channel TREK1 (K(2P)2.1) is expressed widely in brain and has been linked to depression, neuroprotection, pain perception, and epilepsy. Little, however, is known about the regulation of TREK1 expression on the transcriptional and translational level or about its trafficking to the plasma membrane. Here we have used PCR techniques to identify a splice variant of TREK1 expressed in the brain, which encodes a heavily truncated TREK1 protein retaining a single transmembrane domain. Functional expression of this splice variant TREK1ΔEx4 in tsA201 cells in the presence or absence of wild type TREK1 revealed that TREK1ΔEx4 has no channel activity itself but reduced TREK1 whole cell current amplitude. Confocal analysis of the expression of fluorescently tagged TREK1 variants revealed that TREK1ΔEx4 is translated, but it is retained in the intracellular compartment. Additionally, TREK1ΔEx4 reduced the level of TREK1 expression in the plasma membrane. Long and short forms of TREK1 derived from alternative translation initiation are differentially affected by TREK1ΔEx4, with the short form (lacking the first 41 amino acids at its N terminus) unaffected. This differential regulatory role of TREK1ΔEx4 will alter the functional profile of TREK1 current in neurons where they are expressed. These results indicate that the N-terminal domain and first transmembrane domain of TREK1 are likely to be important for channel dimerization and trafficking to the plasma membrane.
Collapse
Affiliation(s)
- Emma L Veale
- Medway School of Pharmacy, The Universities of Kent and Greenwich at Medway, Chatham Maritime, Kent ME4 4TB, United Kingdom
| | | | | | | |
Collapse
|
34
|
Lalle M, Bavassano C, Fratini F, Cecchetti S, Boisguerin P, Crescenzi M, Pozio E. Involvement of 14-3-3 protein post-translational modifications in Giardia duodenalis encystation. Int J Parasitol 2010; 40:201-13. [DOI: 10.1016/j.ijpara.2009.07.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Revised: 07/13/2009] [Accepted: 07/14/2009] [Indexed: 11/28/2022]
|
35
|
Ganesh M, Dave RN, L’Amoreaux W, Gross RA. Embedded Enzymatic Biomaterial Degradation. Macromolecules 2009. [DOI: 10.1021/ma901481h] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Manoj Ganesh
- NSF I/UCRC for Biocatalysis & Bioprocessing of Macromolecules, Polytechnic Institute of NYU, Six Metrotech Center, Brooklyn, New York 11201
| | - Rachna N. Dave
- NSF I/UCRC for Biocatalysis & Bioprocessing of Macromolecules, Polytechnic Institute of NYU, Six Metrotech Center, Brooklyn, New York 11201
| | - William L’Amoreaux
- CUNY College of Staten Island, 2800 Victory Blvd., Staten Island, New York 10314
| | - Richard A. Gross
- NSF I/UCRC for Biocatalysis & Bioprocessing of Macromolecules, Polytechnic Institute of NYU, Six Metrotech Center, Brooklyn, New York 11201
| |
Collapse
|
36
|
Chung JJ, Okamoto Y, Coblitz B, Li M, Qiu Y, Shikano S. PI3K/Akt signalling-mediated protein surface expression sensed by 14-3-3 interacting motif. FEBS J 2009; 276:5547-58. [PMID: 19691494 DOI: 10.1111/j.1742-4658.2009.07241.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The regulation of protein expression on the cell surface membrane is an important component of the cellular response to extracellular signalling. The translation of extracellular signalling into specific protein localization often involves the post-translational modification of cargo proteins. Using a genetic screen of random peptides, we have previously identified a group of C-terminal sequences, represented by RGRSWTY-COOH (termed'SWTY'), which are capable of overriding an endoplasmic reticulum localization signal and directing membrane proteins to the cell surface via specific binding to 14-3-3 proteins. The identity of the kinase signalling pathways that drive phosphorylation and 14-3-3 binding of the SWTY sequence is not known. In this study, we report that the activation of the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) pathway by the over-expression of active kinases, stimulation with fetal bovine serum or growth factors can: (a) phosphorylate the SWTY sequence; (b) recruit 14-3-3 proteins to SWTY; and (c) promote surface expression of the chimeric potassium channel fused with the SWTY sequence. The expression of the dominant negative Akt inhibited the enhancement of surface expression by fetal bovine serum. In addition, the activation of PI3K significantly enhanced the 14-3-3 association and cell surface expression of GPR15, a G protein-coupled receptor which carries an endogenous SWTY-like, C-terminal, 14-3-3 binding sequence and is known to serve as a HIV co-receptor. Given the wealth and specificity of both kinase activity and 14-3-3 binding sequences, our results suggest that the C-terminal SWTYlike motif may serve as a sensor that can selectively induce the cell surface expression of membrane proteins in response to different extracellular signals.
Collapse
Affiliation(s)
- Jean-Ju Chung
- Department of Neuroscience, Johns Hopkins University, Baltimore, MD, USA
| | | | | | | | | | | |
Collapse
|
37
|
Vikstrom KL, Vaidyanathan R, Levinsohn S, O'Connell RP, Qian Y, Crye M, Mills JH, Anumonwo JMB. SAP97 regulates Kir2.3 channels by multiple mechanisms. Am J Physiol Heart Circ Physiol 2009; 297:H1387-97. [PMID: 19633205 DOI: 10.1152/ajpheart.00638.2008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
We examined the impact of coexpressing the inwardly rectifying potassium channel, Kir2.3, with the scaffolding protein, synapse-associated protein (SAP) 97, and determined that coexpression of these proteins caused an approximately twofold increase in current density. A combination of techniques was used to determine if the SAP97-induced increase in Kir2.3 whole cell currents resulted from changes in the number of channels in the cell membrane, unitary channel conductance, or channel open probability. In the absence of SAP97, Kir2.3 was found predominantly in a cytoplasmic, vesicular compartment with relatively little Kir2.3 localized to the plasma membrane. The introduction of SAP97 caused a redistribution of Kir2.3, leading to prominent colocalization of Kir2.3 and SAP97 and a modest increase in cell surface Kir2.3. The median Kir2.3 single channel conductance in the absence of SAP97 was approximately 13 pS, whereas coexpression of SAP97 led to a wide distribution of channel events with three distinct peaks centered at 16, 29, and 42 pS. These changes occurred without altering channel open probability, current rectification properties, or pH sensitivity. Thus association of Kir2.3 with SAP97 in HEK293 cells increased channel cell surface expression and unitary channel conductance. However, changes in single channel conductance play the major role in determining whole cell currents in this model system. We further suggest that the SAP97 effect results from SAP97 binding to the Kir2.3 COOH-terminal domain and altering channel conformation.
Collapse
Affiliation(s)
- Karen L Vikstrom
- Department of Pharmacology, State University of New York Upstate Medical University, Syracuse, New York, USA
| | | | | | | | | | | | | | | |
Collapse
|
38
|
Zuzarte M, Heusser K, Renigunta V, Schlichthörl G, Rinné S, Wischmeyer E, Daut J, Schwappach B, Preisig-Müller R. Intracellular traffic of the K+ channels TASK-1 and TASK-3: role of N- and C-terminal sorting signals and interaction with 14-3-3 proteins. J Physiol 2009; 587:929-52. [PMID: 19139046 PMCID: PMC2673767 DOI: 10.1113/jphysiol.2008.164756] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2008] [Accepted: 01/08/2009] [Indexed: 01/03/2023] Open
Abstract
The two-pore-domain potassium channels TASK-1 (KCNK3) and TASK-3 (KCNK9) modulate the electrical activity of neurons and many other cell types. We expressed TASK-1, TASK-3 and related reporter constructs in Xenopus oocytes, mammalian cell lines and various yeast strains to study the mechanisms controlling their transport to the surface membrane and the role of 14-3-3 proteins. We measured potassium currents with the voltage-clamp technique and fused N- and C-terminal fragments of the channels to various reporter proteins to study changes in subcellular localisation and surface expression. Mutational analysis showed that binding of 14-3-3 proteins to the extreme C-terminus of TASK-1 and TASK-3 masks a tri-basic motif, KRR, which differs in several important aspects from canonical arginine-based (RxR) or lysine-based (KKxx) retention signals. Pulldown experiments with GST fusion proteins showed that the KRR motif in the C-terminus of TASK-3 channels was able to bind to COPI coatomer. Disabling the binding of 14-3-3, which exposes the KRR motif, caused localisation of the GFP-tagged channel protein mainly to the Golgi complex. TASK-1 and TASK-3 also possess a di-basic N-terminal retention signal, KR, whose function was found to be independent of the binding of 14-3-3. Suppression of channel surface expression with dominant-negative channel mutants revealed that interaction with 14-3-3 has no significant effect on the dimeric assembly of the channels. Our results give a comprehensive description of the mechanisms by which 14-3-3 proteins, together with N- and C-terminal sorting signals, control the intracellular traffic of TASK-1 and TASK-3.
Collapse
Affiliation(s)
- Marylou Zuzarte
- Institute of Physiology, Marburg University, Deutschhausstrasse 2, 35037 Marburg, Germany
| | | | | | | | | | | | | | | | | |
Collapse
|
39
|
Tomassi L, Costantini A, Corallino S, Santonico E, Carducci M, Cesareni G, Castagnoli L. The central proline rich region of POB1/REPS2 plays a regulatory role in epidermal growth factor receptor endocytosis by binding to 14-3-3 and SH3 domain-containing proteins. BMC BIOCHEMISTRY 2008; 9:21. [PMID: 18647389 PMCID: PMC2494995 DOI: 10.1186/1471-2091-9-21] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/24/2008] [Accepted: 07/22/2008] [Indexed: 11/10/2022]
Abstract
BACKGROUND The human POB1/REPS2 (Partner of RalBP1) protein is highly conserved in mammals where it has been suggested to function as a molecular scaffold recruiting proteins involved in vesicular traffic and linking them to the actin cytoskeleton remodeling machinery. More recently POB1/REPS2 was found highly expressed in androgen-dependent prostate cancer cell lines, while one of its isoforms (isoform 2) is down regulated during prostate cancer progression. RESULTS In this report we characterize the central proline rich domain of POB1/REPS2 and we describe for the first time its functional role in receptor endocytosis. We show that the ectopic expression of this domain has a dominant negative effect on the endocytosis of activated epidermal growth factor receptor (EGFR) while leaving transferrin receptor endocytosis unaffected. By a combination of different approaches (phage display, bioinformatics predictions, peptide arrays, mutagenic analysis, in vivo co-immunoprecipitation), we have identified two closely spaced binding motifs for 14-3-3 and for the SH3 of the proteins Amphiphysin II and Grb2. Differently from wild type, proline rich domains that are altered in these motifs do not inhibit EGFR endocytosis, suggesting that these binding motifs play a functional role in this process. CONCLUSION Our findings are relevant to the characterization of the molecular mechanism underlying the involvement of POB1/REPS2, SH3 and 14-3-3 proteins in receptor endocytosis, suggesting that 14-3-3 could work by bridging the EGF receptor and the scaffold protein POB1/REPS2.
Collapse
Affiliation(s)
- Laura Tomassi
- Department of Biology, University of Rome Tor Vergata, Via della Ricerca Scientifica, 00133 Rome, Italy.
| | | | | | | | | | | | | |
Collapse
|
40
|
Schwappach B. An overview of trafficking and assembly of neurotransmitter receptors and ion channels (Review). Mol Membr Biol 2008; 25:270-8. [PMID: 18446613 DOI: 10.1080/09687680801960998] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Ionotropic neurotransmitter receptors and voltage-gated ion channels assemble from several homologous and non-homologous subunits. Assembly of these multimeric membrane proteins is a tightly controlled process subject to primary and secondary quality control mechanisms. An assembly pathway involving a dimerization of dimers has been demonstrated for a voltage-gated potassium channel and for different types of glutamate receptors. While many novel C-terminal assembly domains have been identified in various members of the voltage-gated cation channel superfamily, the assembly pathways followed by these proteins remain largely elusive. Recent progress on the recognition of polar residues in the transmembrane segments of membrane proteins by the retrieval factor Rer1 is likely to be relevant for the further investigation of trafficking defects in channelopathies. This mechanism might also contribute to controlling the assembly of ion channels by retrieving unassembled subunits to the endoplasmic reticulum. The endoplasmic reticulum is a metabolic compartment studded with small molecule transporters. This environment provides ligands that have recently been shown to act as pharmacological chaperones in the biogenesis of ligand-gated ion channels. Future progress depends on the improvement of tools, in particular the antibodies used by the field, and the continued exploitation of genetically tractable model organisms in screens and physiological experiments.
Collapse
|
41
|
Sayat R, Leber B, Grubac V, Wiltshire L, Persad S. O-GlcNAc-glycosylation of beta-catenin regulates its nuclear localization and transcriptional activity. Exp Cell Res 2008; 314:2774-87. [PMID: 18586027 DOI: 10.1016/j.yexcr.2008.05.017] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2008] [Revised: 04/30/2008] [Accepted: 05/21/2008] [Indexed: 10/22/2022]
Abstract
Beta-catenin plays a role in intracellular adhesion and regulating gene expression. The latter role is associated with its oncogenic properties. Phosphorylation of beta-catenin controls its intracellular expression but mechanism/s that regulates the nuclear localization of beta-catenin is unknown. We demonstrate that O-GlcNAc glycosylation (O-GlcNAcylation) of beta-catenin negatively regulates its levels in the nucleus. We show that normal prostate cells (PNT1A) have significantly higher amounts of O-GlcNAcylated beta-catenin compared to prostate cancer (CaP) cells. The total nuclear levels of beta-catenin are higher in the CaP cells than PNT1A but only a minimal fraction of the nuclear beta-catenin in the CaP cells are O-GlcNAcylated. Increasing the levels of O-GlcNAcylated beta-catenin in the CaP cells with PUGNAc (O- (2-acetamido-2-deoxy-d-gluco-pyranosylidene) amino-N-phenylcarbamate) treatment is associated with a progressive decrease in the levels of beta-catenin in the nucleus. TOPFlash reporter assay and mRNA expressions of beta-catenin's target genes indicate that O-GlcNAcylation of beta-catenin results in a decrease in its transcriptional activity. We define a novel modification of beta-catenin that regulates its nuclear localization and transcriptional function.
Collapse
Affiliation(s)
- Ria Sayat
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada L8N 3Z5
| | | | | | | | | |
Collapse
|
42
|
Murphy N, Bonner HP, Ward MW, Murphy BM, Prehn JHM, Henshall DC. Depletion of 14-3-3 zeta elicits endoplasmic reticulum stress and cell death, and increases vulnerability to kainate-induced injury in mouse hippocampal cultures. J Neurochem 2008; 106:978-88. [PMID: 18466333 DOI: 10.1111/j.1471-4159.2008.05447.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
14-3-3 proteins are ubiquitous signalling molecules that regulate development and survival pathways in brain. Altered expression and cellular localization of 14-3-3 proteins has been implicated in neurodegenerative diseases and in neuronal death after acute neurological insults, including seizures. Presently, we examined expression and function of 14-3-3 isoforms in vitro using mouse organotypic hippocampal cultures. Treatment of cultures with the endoplasmic reticulum (ER) stressor tunicamycin caused an increase in levels of 14-3-3 zeta within the ER-containing microsomal fraction, along with up-regulation of Lys-Asp-Glu-Leu-containing proteins and calnexin, and the selective death of dentate granule cells. Depletion of 14-3-3 zeta levels using small interfering RNA induced both ER stress proteins and death of granule cells. Treatment of hippocampal cultures with the excitotoxin kainic acid increased levels of Lys-Asp-Glu-Leu-containing proteins and microsomal 14-3-3 zeta levels and caused cell death within the CA1, CA3 and dentate gyrus of the hippocampus. Kainic acid-induced damage was significantly increased in each hippocampal subfield of cultures treated with small interfering RNA targeting 14-3-3 zeta. The present data indicate a role for 14-3-3 zeta in survival responses following ER stress and possibly protection against seizure injury to the hippocampus.
Collapse
Affiliation(s)
- Niamh Murphy
- Department of Physiology & Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland, UK
| | | | | | | | | | | |
Collapse
|
43
|
Rosenberg MM, Yang F, Giovanni M, Mohn JL, Temburni MK, Jacob MH. Adenomatous polyposis coli plays a key role, in vivo, in coordinating assembly of the neuronal nicotinic postsynaptic complex. Mol Cell Neurosci 2008; 38:138-52. [PMID: 18407517 DOI: 10.1016/j.mcn.2008.02.006] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2007] [Revised: 01/30/2008] [Accepted: 02/10/2008] [Indexed: 11/27/2022] Open
Abstract
The neuronal nicotinic synapse plays a central role in normal cognitive and autonomic function. Molecular mechanisms that direct the assembly of this synapse remain poorly defined, however. We show here that adenomatous polyposis coli (APC) organizes a multi-molecular complex that is essential for targeting alpha3(*)nAChRs to synapses. APC interaction with microtubule plus-end binding protein EB1 is required for alpha3(*)nAChR surface membrane insertion and stabilization. APC brings together EB1, the key cytoskeletal regulators macrophin and IQGAP1, and 14-3-3 adapter protein at nicotinic synapses. 14-3-3, in turn, links the alpha3-subunit to APC. This multi-molecular APC complex stabilizes the local microtubule and F-actin cytoskeleton and links postsynaptic components to the cytoskeleton--essential functions for controlling the molecular composition and stability of synapses. This work identifies macrophin, IQGAP1 and 14-3-3 as novel nicotinic synapse components and defines a new role for APC as an in vivo coordinator of nicotinic postsynaptic assembly in vertebrate neurons.
Collapse
Affiliation(s)
- Madelaine M Rosenberg
- Department of Neuroscience, Tufts University School of Medicine, 136 Harrison Ave., Boston, MA 02111, USA
| | | | | | | | | | | |
Collapse
|
44
|
Latz A, Becker D, Hekman M, Müller T, Beyhl D, Marten I, Eing C, Fischer A, Dunkel M, Bertl A, Rapp UR, Hedrich R. TPK1, a Ca(2+)-regulated Arabidopsis vacuole two-pore K(+) channel is activated by 14-3-3 proteins. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2007; 52:449-59. [PMID: 17764516 DOI: 10.1111/j.1365-313x.2007.03255.x] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
The vacuole represents a pivotal plant organelle for management of ion homeostasis, storage of proteins and solutes, as well as deposition of cytotoxic compounds. Ion channels, pumps and carriers in the vacuolar membrane under control of cytosolic factors provide for ionic and metabolic homeostasis between this storage organelle and the cytoplasm. Here we show that AtTPK1 (KCO1), a vacuolar membrane localized K(+) channel of the TPK family, interacts with 14-3-3 proteins (general regulating factors, GRFs). Following in planta expression TPK1 and GRF6 co-localize at the vacuolar membrane. Co-localization of wild-type TPK1, but not the TPK1-S42A mutant, indicates that phosphorylation of the 14-3-3 binding motif of TPK1 represents a prerequisite for interaction. Pull-down assays and surface plasmon resonance measurements revealed GRF6 high-affinity interaction with TPK1. Following expression of TPK1 in yeast and isolation of vacuoles, patch-clamp studies identified TPK1 as a voltage-independent and Ca(2+)-activated K(+) channel. Addition of 14-3-3 proteins strongly increased the TPK1 activity in a dose-dependent manner. However, an inverse effect of GRF6 on the activity of the slow-activating vacuolar (SV) channel was observed in mesophyll vacuoles from Arabidopsis thaliana. Thus, TPK1 seems to provide for a Ca(2+)- and 14-3-3-sensitive mechanism capable of controlling cytoplasmic potassium homeostasis in plants.
Collapse
Affiliation(s)
- A Latz
- Department of Molecular Plant Physiology and Biophysics, Julius-von-Sachs-Institute, Biocenter, University of Würzburg, Julius-von-Sachs-Platz 2, 97082 Würzburg, Germany
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
45
|
Abstract
Surface expression of the K(2P)3.1 two-pore domain potassium channel is regulated by phosphorylation-dependent binding of 14-3-3, leading to suppression of coatomer coat protein I (COPI)-mediated retention in endoplasmic reticulum (ER). Here, we investigate the nature of the macromolecular regulatory complexes that mediate forward and retrograde transport. We demonstrate that (i) the channel employs two separate but interacting COPI binding sites on the N- and C-termini; (ii) disrupting COPI binding to either site interferes with the ER retention; (iii) p11 and 14-3-3 do not interact on their own; (iv) p11 binding to the C-terminal retention motif is dependent on 14-3-3; and (v) p11 is coexpressed in only a subset of tissues with K(2P)3.1, while 14-3-3 expression is ubiquitous. We conclude that K(2P)3.1 forward transport requires 14-3-3 suppression of COPI binding, whereas p11 serves a modulatory role.
Collapse
Affiliation(s)
- Ita O'Kelly
- The Faculty of Life Sciences, The University of Manchester, 46 Grafton Street, Manchester, M13 9NT, UK. ita.o'
| | | |
Collapse
|
46
|
Mekhail K, Rivero-Lopez L, Al-Masri A, Brandon C, Khacho M, Lee S. Identification of a common subnuclear localization signal. Mol Biol Cell 2007; 18:3966-77. [PMID: 17652456 PMCID: PMC1995723 DOI: 10.1091/mbc.e07-03-0295] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Proteins share peptidic sequences, such as a nuclear localization signal (NLS), which guide them to particular membrane-bound compartments. Similarities have also been observed within different classes of signals that target proteins to membrane-less subnuclear compartments. Common localization signals affect spatial and temporal subcellular organization and are thought to allow the coordinated response of different molecular networks to a given signaling cue. Here we identify a higher-order and predictive code, {[RR(I/L)X(3)r]((n, n > or = 1))+[L(phi/N)(V/L)]((n,n>1))}, that establishes high-affinity interactions between a group of proteins and the nucleolus in response to a specific signal. This position-independent code is referred to as a nucleolar detention signal regulated by H(+) (NoDS(H+)) and the class of proteins includes the cIAP2 apoptotic regulator, VHL ubiquitylation factor, HSC70 heat shock protein and RNF8 transcription regulator. By identifying a common subnuclear targeting consensus sequence, our work reveals rules governing the dynamics of subnuclear organization and ascribes new modes of regulation to several proteins with diverse steady-state distributions and dynamic properties.
Collapse
Affiliation(s)
- Karim Mekhail
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ONT, Canada, K1H 8M5
| | - Luis Rivero-Lopez
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ONT, Canada, K1H 8M5
| | - Ahmad Al-Masri
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ONT, Canada, K1H 8M5
| | - Caroline Brandon
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ONT, Canada, K1H 8M5
| | - Mireille Khacho
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ONT, Canada, K1H 8M5
| | - Stephen Lee
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ONT, Canada, K1H 8M5
| |
Collapse
|
47
|
Zuzarte M, Rinné S, Schlichthörl G, Schubert A, Daut J, Preisig-Müller R. A di-acidic sequence motif enhances the surface expression of the potassium channel TASK-3. Traffic 2007; 8:1093-100. [PMID: 17547699 DOI: 10.1111/j.1600-0854.2007.00593.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
We have characterized a sequence motif, EDE, in the proximal C-terminus of the acid-sensitive potassium channel TASK-3. Human TASK-3 channels were expressed in Xenopus oocytes, and the density of the channels at the surface membrane was studied with two complementary techniques: a luminometric surface expression assay of hemagglutinin epitope-tagged TASK-3 channels and voltage-clamp measurements of the acid-sensitive potassium current. Both approaches showed that mutation of the two glutamate residues of the EDE motif to alanine (ADA mutant) markedly reduced the transport of TASK-3 channels to the cell surface. Mutation of the central aspartate of the EDE motif had no effect on surface expression. The functional role of the EDE motif was further characterized in chimaeric constructs consisting of truncated Kir2.1 channels to which the C-terminus of TASK-3 was attached. In these constructs, too, replacement of the EDE motif by ADA strongly reduced surface expression. Live-cell imaging of enhanced green fluorescent protein-tagged channels expressed in COS-7 cells showed that 24 h after transfection wild-type TASK-3 was mainly localized to the cell surface whereas the ADA mutant was largely retained in the endoplasmic reticulum (ER). Mutation of a second di-acidic motif in the C-terminus of TASK-3 (DAE) had no effect on surface expression. Coexpression of TASK-3 with a GTP-restricted mutant of the coat recruitment GTPase Sar1 (Sar1H79G) resulted in ER retention of the channel. Our data suggest that the di-acidic motif, EDE, in human TASK-3 is a major determinant of the rate of ER export and is required for efficient surface expression of the channel.
Collapse
Affiliation(s)
- Marylou Zuzarte
- Institute of Physiology, Marburg University, Deutschhausstr. 2, 35037 Marburg, Germany
| | | | | | | | | | | |
Collapse
|
48
|
Heusser K, Yuan H, Neagoe I, Tarasov AI, Ashcroft FM, Schwappach B. Scavenging of 14-3-3 proteins reveals their involvement in the cell-surface transport of ATP-sensitive K+ channels. J Cell Sci 2007; 119:4353-63. [PMID: 17038548 DOI: 10.1242/jcs.03196] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Arginine (Arg)-based endoplasmic reticulum (ER)-localization signals are involved in the quality control of different heteromultimeric membrane protein complexes. ATP-sensitive potassium (KATP) channels are unique because each subunit in the heterooctamer contains an Arg-based ER-localization signal. We have dissected the inactivation events that override the ER-localization activity of the eight peptide-sorting motifs. Employing a 14-3-3-scavenger construct to lower the availability of 14-3-3 proteins, we found that 14-3-3 proteins promote the cell-surface expression of heterologously expressed and native KATP channels. 14-3-3 proteins were detected in physical association with KATP channels in a pancreatic beta-cell line. Our results suggest that the Arg-based signal present in Kir6.2 is sterically masked by the SUR1 subunit. By contrast, 14-3-3 proteins functionally antagonized the Arg-based signal present in SUR1. The last ten amino acids were required for efficient 14-3-3 recruitment to multimeric forms of the Kir6.2 C-terminus. Channels containing a pore-forming subunit lacking these residues reached the cell surface inefficiently but were functionally indistinguishable from channels formed by the full-length subunits. In conclusion, 14-3-3 proteins promote the cell-surface transport of correctly assembled complexes but do not regulate the activity of KATP channels at the cell surface.
Collapse
Affiliation(s)
- Katja Heusser
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | | | | | | | | | | |
Collapse
|
49
|
Wu M, Coblitz B, Shikano S, Long S, Spieker M, Frutos AG, Mukhopadhyay S, Li M. Phospho-specific recognition by 14-3-3 proteins and antibodies monitored by a high throughput label-free optical biosensor. FEBS Lett 2006; 580:5681-9. [PMID: 17011553 DOI: 10.1016/j.febslet.2006.09.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2006] [Revised: 08/29/2006] [Accepted: 09/07/2006] [Indexed: 10/24/2022]
Abstract
Label-free detection of molecular interactions has considerable potential in facilitating assay development. When combined with high throughput capability, it may be applied to small molecule screens for drug candidates. Phosphorylation is a key posttranslational process that confers diverse regulation in biological systems involving specific protein-protein interactions recognizing the phosphorylated motifs. Using a resonant waveguide grating biosensor, the Epic mark System, we have developed a generic assay to quantitatively measure phospho-specific interactions between a trafficking signal-phosphorylated SWTY peptide and 14-3-3 proteins or anti-phosphopeptide antibodies. Compared with a solution-based fluorescence anisotropy assay, our results support that the high throughput resonant waveguide grating biosensor system has favorable technical profiles in detecting protein-protein interactions that recognize phosphorylated motifs. Hence it provides a new generic HTS platform for phospho-detection.
Collapse
Affiliation(s)
- Meng Wu
- Department of Neuroscience and High Throughput Biology Center, School of Medicine, Johns Hopkins University, BRB311, 733 North Broadway, Baltimore, MD 21205, USA
| | | | | | | | | | | | | | | |
Collapse
|
50
|
Shikano S, Coblitz B, Wu M, Li M. 14-3-3 proteins: regulation of endoplasmic reticulum localization and surface expression of membrane proteins. Trends Cell Biol 2006; 16:370-5. [PMID: 16769213 DOI: 10.1016/j.tcb.2006.05.006] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2006] [Revised: 03/31/2006] [Accepted: 05/24/2006] [Indexed: 11/24/2022]
Abstract
The density and composition of cell surface proteins are major determinants for cellular functions. Regulation of cell surface molecules occurs at several levels, including the efficiency of surface transport, and is therefore of great interest. As the major phosphoprotein-binding modules, 14-3-3 proteins are known for their crucial roles in a wide range of cellular activities, including the subcellular localization of target proteins. Accumulating evidence suggests a role for 14-3-3 in surface transport of membrane proteins, in which 14-3-3 binding reduces endoplasmic reticulum (ER) localization, thereby promoting surface expression of membrane proteins. Here, we focus on recent evidence of 14-3-3-mediated surface transport and discuss the possible molecular mechanisms.
Collapse
Affiliation(s)
- Sojin Shikano
- Department of Neuroscience and High Throughput Biology Center, School of Medicine, Johns Hopkins University, 733 North Broadway, Baltimore, MD 21205, USA
| | | | | | | |
Collapse
|