151
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Tanaka H, Kitakura S, De Rycke R, De Groodt R, Friml J. Fluorescence imaging-based screen identifies ARF GEF component of early endosomal trafficking. Curr Biol 2009; 19:391-7. [PMID: 19230664 DOI: 10.1016/j.cub.2009.01.057] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2008] [Revised: 12/23/2008] [Accepted: 01/13/2009] [Indexed: 01/08/2023]
Abstract
Endocytic vesicle trafficking is crucial for regulating activity and localization of plasma membrane components, but the process is still poorly genetically defined in plants. Membrane proteins of the PIN-FORMED (PIN) family exhibit polar localization in plant cells and facilitate cellular efflux of the plant hormone auxin, thereby regulating multiple developmental processes. PIN proteins undergo constitutive endocytosis and GNOM ARF GEF-dependent recycling, and their localization is under extensive regulation by developmental and environmental cues. We designed a fluorescence imaging-based screen to identify Arabidopsis thaliana mutants defective in internalization of proteins including PINs from the plasma membrane. We identified three mutant loci, BFA-visualized endocytic trafficking defective1 (ben1) through ben3 that do not efficiently accumulate PIN1-GFP in intracellular compartments after inhibition of recycling and secretion by fungal toxin brefeldin A (BFA). Fine mapping revealed that BEN1 encodes an ARF GEF vesicle trafficking regulator from the functionally uncharacterized BIG class. ben1 mutant has been previously implicated in pathogen response and shows cell polarity, BFA sensitivity, and growth defects. BEN1 is involved in endocytosis of plasma membrane proteins and localizes to early endocytic compartments distinct from GNOM-positive endosomes. Our results identify BEN1 as the ARF GEF mediating early endosomal traffic.
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Affiliation(s)
- Hirokazu Tanaka
- Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB) and Department of Molecular Genetics, Ghent University, 9052 Gent, Belgium
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152
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Brach T, Soyk S, Müller C, Hinz G, Hell R, Brandizzi F, Meyer AJ. Non-invasive topology analysis of membrane proteins in the secretory pathway. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2009; 57:534-41. [PMID: 18939964 DOI: 10.1111/j.1365-313x.2008.03704.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
We present a novel method to experimentally visualize in vivo the topology of transmembrane proteins residing in the endoplasmic reticulum (ER) membrane or passing through the secretory pathway on their way to their final destination. This approach, so-called redox-based topology analysis (ReTA), is based on fusion of transmembrane proteins with redox-sensitive GFP (roGFP) and ratiometric imaging. The ratio images provide direct information on the orientation of roGFP relative to the membrane as the roGFP fluorescence alters with changes in the glutathione redox potential across the ER membrane. As proof of concept, we produced binary read-outs using oxidized roGFP inside the ER lumen and reduced roGFP on the cytosolic side of the membrane for both N- and C-terminal fusions of single and multi-spanning membrane proteins. Further, successive deletion of hydrophobic domains from the C-terminus of the K/HDEL receptor ERD2 resulted in alternating localization of roGFP and a topology model for AtERD2 with six transmembrane domains.
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Affiliation(s)
- Thorsten Brach
- Heidelberg Institute for Plant Science, University of Heidelberg, Im Neuenheimer Feld 360, D-69120 Heidelberg, Germany
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153
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Signaling in Vesicle Traffic: Protein-Lipid Interface in Regulation of Plant Endomembrane Dynamics. SIGNALING IN PLANTS 2009. [DOI: 10.1007/978-3-540-89228-1_6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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154
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Titapiwatanakun B, Murphy AS. Post-transcriptional regulation of auxin transport proteins: cellular trafficking, protein phosphorylation, protein maturation, ubiquitination, and membrane composition. JOURNAL OF EXPERIMENTAL BOTANY 2009; 60:1093-107. [PMID: 18824505 DOI: 10.1093/jxb/ern240] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Auxin concentration gradients, established by polar transport of auxin, are essential for the establishment and maintenance of polar growth and morphological patterning. Three families of cellular transport proteins, PIN-formed (PIN), P-glycoprotein (ABCB/PGP), and AUXIN RESISTANT 1/LIKE AUX1 (AUX1/LAX), can independently and co-ordinately transport auxin in plants. Regulation of these proteins involves intricate and co-ordinated cellular processes, including protein-protein interactions, vesicular trafficking, protein phosphorylation, ubiquitination, and stabilization of the transporter complexes on the plasma membrane.
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155
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Ebine K, Ueda T. Unique mechanism of plant endocytic/vacuolar transport pathways. JOURNAL OF PLANT RESEARCH 2009; 122:21-30. [PMID: 19082690 DOI: 10.1007/s10265-008-0200-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2008] [Accepted: 10/23/2008] [Indexed: 05/08/2023]
Abstract
The post-Golgi traffic network in plant cells is highly complex, which is correlated with the large number of genes related to this function. RABs and SNAREs are key regulators of tethering and fusion of transport vesicles to target membranes, and the numbers of these regulators have also expanded in plant lineages. In addition to this increase in the net number of genes, plants also seem to have evolved new gene families tailored to fulfill plant-unique functions. In this article, we summarize recent progress in studies on plant-unique RABs and SNAREs functioning in post-Golgi trafficking, with a special focus on the endocytic pathway.
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Affiliation(s)
- Kazuo Ebine
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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156
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Titapiwatanakun B, Blakeslee JJ, Bandyopadhyay A, Yang H, Mravec J, Sauer M, Cheng Y, Adamec J, Nagashima A, Geisler M, Sakai T, Friml J, Peer WA, Murphy AS. ABCB19/PGP19 stabilises PIN1 in membrane microdomains in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2009; 57:27-44. [PMID: 18774968 DOI: 10.1111/j.1365-313x.2008.03668.x] [Citation(s) in RCA: 170] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Auxin transport is mediated at the cellular level by three independent mechanisms that are characterised by the PIN-formed (PIN), P-glycoprotein (ABCB/PGP) and AUX/LAX transport proteins. The PIN and ABCB transport proteins, best represented by PIN1 and ABCB19 (PGP19), have been shown to coordinately regulate auxin efflux. When PIN1 and ABCB19 coincide on the plasma membrane, their interaction enhances the rate and specificity of auxin efflux and the dynamic cycling of PIN1 is reduced. However, ABCB19 function is not regulated by the dynamic cellular trafficking mechanisms that regulate PIN1 in apical tissues, as localisation of ABCB19 on the plasma membrane was not inhibited by short-term treatments with latrunculin B, oryzalin, brefeldin A (BFA) or wortmannin--all of which have been shown to alter PIN1 and/or PIN2 plasma membrane localisation. When taken up by endocytosis, the styryl dye FM4-64 labels diffuse rather than punctuate intracellular bodies in abcb19 (pgp19), and some aggregations of PIN1 induced by short-term BFA treatment did not disperse after BFA washout in abcb19. Although the subcellular localisations of ABCB19 and PIN1 in the reciprocal mutant backgrounds were like those in wild type, PIN1 plasma membrane localisation in abcb19 roots was more easily perturbed by the detergent Triton X-100, but not other non-ionic detergents. ABCB19 is stably associated with sterol/sphingolipid-enriched membrane fractions containing BIG/TIR3 and partitions into Triton X-100 detergent-resistant membrane (DRM) fractions. In the wild type, PIN1 was also present in DRMs, but was less abundant in abcb19 DRMs. These observations suggested a rationale for the observed lack of auxin transport activity when PIN1 is expressed in a non-plant heterologous system. PIN1 was therefore expressed in Schizosaccharomyces pombe, which has plant-like sterol-enriched microdomains, and catalysed auxin transport in these cells. These data suggest that ABCB19 stabilises PIN1 localisation at the plasma membrane in discrete cellular subdomains where PIN1 and ABCB19 expression overlaps.
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157
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Kleine-Vehn J, Friml J. Polar targeting and endocytic recycling in auxin-dependent plant development. Annu Rev Cell Dev Biol 2008; 24:447-73. [PMID: 18837671 DOI: 10.1146/annurev.cellbio.24.110707.175254] [Citation(s) in RCA: 182] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Plant development is characterized by a profound phenotypic plasticity that often involves redefining of the developmental fate and polarity of cells within differentiated tissues. The plant hormone auxin and its directional intercellular transport play a major role in these processes because they provide positional information and link cell polarity with tissue patterning. This plant-specific mechanism of transport-dependent auxin gradients depends on subcellular dynamics of auxin transport components, in particular on endocytic recycling and polar targeting. Recent insights into these cellular processes in plants have revealed important parallels to yeast and animal systems, including clathrin-dependent endocytosis, retromer function, and transcytosis, but have also emphasized unique features of plant cells such as diversity of polar targeting pathways; integration of environmental signals into subcellular trafficking; and the link between endocytosis, cell polarity, and cell fate specification. We review these advances and focus on the translation of the subcellular dynamics to the regulation of whole-plant development.
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Affiliation(s)
- Jürgen Kleine-Vehn
- Department of Plant Systems Biology, VIB, and Department of Molecular Genetics, Ghent University, 9052 Ghent, Belgium
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158
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Abstract
Cell polarization is intimately linked to plant development, growth, and responses to the environment. Major advances have been made in our understanding of the signaling pathways and networks that regulate cell polarity in plants owing to recent studies on several model systems, e.g., tip growth in pollen tubes, cell morphogenesis in the leaf epidermis, and polar localization of PINs. From these studies we have learned that plant cells use conserved mechanisms such as Rho family GTPases to integrate both plant-specific and conserved polarity cues and to coordinate the cytoskeketon dynamics/reorganization and vesicular trafficking required for polarity establishment and maintenance. This review focuses upon signaling mechanisms for cell polarity formation in Arabidopsis, with an emphasis on Rho GTPase signaling in polarized cell growth and how these mechanisms compare with those for cell polarity signaling in yeast and animal systems.
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Affiliation(s)
- Zhenbiao Yang
- Center for Plant Cell Biology, Department of Botany and Plant Sciences, University of California, Riverside, California 92521-0124, USA.
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159
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Woollard AAD, Moore I. The functions of Rab GTPases in plant membrane traffic. CURRENT OPINION IN PLANT BIOLOGY 2008; 11:610-9. [PMID: 18952493 DOI: 10.1016/j.pbi.2008.09.010] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2008] [Revised: 09/02/2008] [Accepted: 09/11/2008] [Indexed: 05/08/2023]
Abstract
Rab GTPases are important determinants of membrane identity and membrane targeting. Higher plants have evolved a unique set of Rab GTPases that presumably reflects the specific demands of plant cell trafficking. In recent years, significant progress has been made in identifying Rab GTPases involved in endosome organisation, cytokinesis and in post-Golgi traffic to the plasma membrane and vacuoles. These include members of the Rab-F1, Rab-F2, Rab-A1, Rab-A2 and Rab-A4 subclasses. Some important regulators or effectors have also been identified for Rab-F, Rab-A1 and Rab-A4 proteins. However, uncertainties remain about the trafficking pathways that connect the compartments in the trans-Golgi/prevacuolar/endosomal system and there is still little or no insight into the functions of several major subclasses within the Rab GTPase family.
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Affiliation(s)
- Astrid A D Woollard
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK
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160
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Wei T, Wang A. Biogenesis of cytoplasmic membranous vesicles for plant potyvirus replication occurs at endoplasmic reticulum exit sites in a COPI- and COPII-dependent manner. J Virol 2008; 82:12252-64. [PMID: 18842721 PMCID: PMC2593340 DOI: 10.1128/jvi.01329-08] [Citation(s) in RCA: 134] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2008] [Accepted: 09/29/2008] [Indexed: 12/31/2022] Open
Abstract
Single-stranded positive-sense RNA viruses induce the biogenesis of cytoplasmic membranous vesicles, where viral replication takes place. However, the mechanism underlying this characteristic vesicular proliferation remains poorly understood. Previously, a 6-kDa potyvirus membrane protein (6K) was shown to interact with the endoplasmic reticulum (ER) and to induce the formation of the membranous vesicles. In this study, the involvement of the early secretory pathway in the formation of the 6K-induced vesicles was investigated in planta. By means of live-cell imaging, it was found that the 6K protein was predominantly colocalized with Sar1, Sec23, and Sec24, which are known markers of ER exit sites (ERES). The localization of 6K at ERES was prevented by the coexpression of a dominant-negative mutant of Sar1 that disables the COPII activity or by the coexpression of a mutant of Arf1 that disrupts the COPI complex. The secretion of a soluble secretory marker targeting the apoplast was arrested at the level of the ER in cells overexpressing 6K or infected by a potyvirus. This blockage of protein trafficking out of the ER by 6K and the distribution of 6K toward the ERES may account for the aggregation of the 6K-bound vesicles. Finally, virus infection was reduced when the accumulation of 6K at ERES was inhibited by impairing either the COPI or COPII complex. Taken together, these results imply that the cellular COPI and COPII coating machineries are involved in the biogenesis of the potyvirus 6K vesicles at the ERES for viral-genome replication.
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Affiliation(s)
- Taiyun Wei
- Southern Crop Protection and Food Research Centre, AAFC, 1391 Sandford Street, London, Ontario N5V 4T3, Canada
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161
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Gao X, Nagawa S, Wang G, Yang Z. Cell polarity signaling: focus on polar auxin transport. MOLECULAR PLANT 2008; 1:899-909. [PMID: 19825591 PMCID: PMC2902905 DOI: 10.1093/mp/ssn069] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Polar auxin transport, which is required for the formation of auxin gradients and directional auxin flows that are critical for plant pattern formation, morphogenesis, and directional growth response to vectorial cues, is mediated by polarized sub-cellular distribution of PIN-FORMED Proteins (PINs, auxin efflux carriers), AUX1/AUX1-like proteins (auxin influx facilitators), and multidrug resistance P-glycoproteins (MDR/PGP). Polar localization of these proteins is controlled by both developmental and environmental cues. Recent studies have revealed cellular (endocytosis, transcytosis, and endosomal sorting and recycling) and molecular (PINOID kinase, protein phosphatase 2A) mechanisms underlying the polar distribution of these auxin transport proteins. Both TIR1-mediated auxin signaling and TIR1-independent auxin-mediated endocytosis have been shown to regulate polar PIN localization and auxin flow, implicating auxin as a self-organizing signal in directing polar transport and directional flows.
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Affiliation(s)
- Xiaowei Gao
- Key Laboratory of Arid and Grassland Agroeology at Lanzhou University, Ministry of Education, Lanzhou 730000, China
- CAU–UCR Joint Center for Biological Science, China Agricultural University, Beijing 100094, China
| | - Shingo Nagawa
- Center for Plant Cell Biology and Department of Botany and Plant Science, University of California, Riverside, CA 92521, USA
| | - Genxuan Wang
- College of Life Science, Zhejiang University, Hangzhou 310029, China
| | - Zhenbiao Yang
- CAU–UCR Joint Center for Biological Science, China Agricultural University, Beijing 100094, China
- Center for Plant Cell Biology and Department of Botany and Plant Science, University of California, Riverside, CA 92521, USA
- To whom correspondence should be addressed. E-mail , fax 9011-886-2-2651-6234, tel. 951-827-7351
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162
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Kleine-Vehn J, Langowski L, Wisniewska J, Dhonukshe P, Brewer PB, Friml J. Cellular and molecular requirements for polar PIN targeting and transcytosis in plants. MOLECULAR PLANT 2008; 1:1056-1066. [PMID: 19825603 DOI: 10.1093/mp/ssn062] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The polar, sub-cellular localization of PIN auxin efflux carriers determines the direction of intercellular auxin flow, thus defining the spatial aspect of auxin signalling. Dynamic, transcytosis-like relocalizations of PIN proteins occur in response to external and internal signals, integrating these signals into changes in auxin distribution. Here, we examine the cellular and molecular mechanisms of polar PIN delivery and transcytosis. The mechanisms of the ARF-GEF-dependent polar targeting and transcytosis are well conserved and show little variations among diverse Arabidopsis ecotypes consistent with their fundamental importance in regulating plant development. At the cellular level, we refine previous findings on the role of the actin cytoskeleton in apical and basal PIN targeting, and identify a previously unknown role for microtubules, specifically in basal targeting. PIN protein delivery to different sides of the cell is mediated by ARF-dependent trafficking with a previously unknown complex level of distinct ARF-GEF vesicle trafficking regulators. Our data suggest that alternative recruitment of PIN proteins by these distinct pathways can account for cell type- and cargo-specific aspects of polar targeting, as well as for polarity changes in response to different signals. The resulting dynamic PIN positioning to different sides of cells defines a three-dimensional pattern of auxin fluxes within plant tissues.
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Affiliation(s)
- Jürgen Kleine-Vehn
- Department of Plant Systems Biology, Ghent University, 9052 Gent, Belgium
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163
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Yadav RK, Fulton L, Batoux M, Schneitz K. The Arabidopsis receptor-like kinase STRUBBELIG mediates inter-cell-layer signaling during floral development. Dev Biol 2008; 323:261-70. [DOI: 10.1016/j.ydbio.2008.08.010] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2008] [Revised: 08/07/2008] [Accepted: 08/08/2008] [Indexed: 11/26/2022]
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164
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165
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Robert HS, Offringa R. Regulation of auxin transport polarity by AGC kinases. CURRENT OPINION IN PLANT BIOLOGY 2008; 11:495-502. [PMID: 18640868 DOI: 10.1016/j.pbi.2008.06.004] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2008] [Revised: 06/11/2008] [Accepted: 06/11/2008] [Indexed: 05/18/2023]
Abstract
The plant hormone auxin controls plant development through gradients and maxima that are generated by PIN efflux carrier driven polar auxin transport. PIN proteins direct this cell-to-cell auxin transport, and thus orient plant development through their asymmetric subcellular distribution. PIN polarity is regulated by PINOID and the phototropins, members of the AGC protein serine/threonine kinase family. Here we review the signaling pathways of these kinases and the role of calcium and BTB proteins in translating both internal and external signals into developmental responses via PIN relocalization, to adapt plant development to changing environmental conditions.
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Affiliation(s)
- Hélène S Robert
- Department of Molecular and Developmental Genetics, Institute of Biology, Leiden University, Wassenaarseweg 64, 2333 AL Leiden, The Netherlands
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166
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Bar M, Aharon M, Benjamin S, Rotblat B, Horowitz M, Avni A. AtEHDs, novel Arabidopsis EH-domain-containing proteins involved in endocytosis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2008; 55:1025-38. [PMID: 18547399 DOI: 10.1111/j.1365-313x.2008.03571.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
SUMMARY Endocytosis is an essential process by which the eukaryotic cell internalizes exogenous material. Studies in yeast and mammalian cells have revealed that endocytosis is a complex molecular process depending on regulated interactions between a variety of proteins and lipids through specific modules. One such module is the Eps15 homology (EH) domain, a conserved modular protein-interaction domain found in several endocytic proteins. The EH-domain-containing proteins function as regulators of endocytosis through their ability to interact with other proteins involved in this process. Here we describe the isolation and characterization of two Arabidopsis EH-domain-containing proteins (AtEHD1 and AtEHD2). We show that the two proteins are involved in endocytosis in plant systems and demonstrate that the Arabidopsis EHD proteins function similarly to mammalian EHDs. Similarly to hEHD2, over-expression of AtEHD2 has an inhibitory effect on endocytosis. While transgenic plants over-expressing AtEHD1 had no detectable phenotype, downregulation of AtEHD1 caused retardation of entry of endocytosed material into plant cells.
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Affiliation(s)
- Maya Bar
- Department of Plant Sciences, Tel-Aviv University, Tel Aviv 69978, Israel
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167
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Nielsen E, Cheung AY, Ueda T. The regulatory RAB and ARF GTPases for vesicular trafficking. PLANT PHYSIOLOGY 2008; 147:1516-26. [PMID: 18678743 PMCID: PMC2492611 DOI: 10.1104/pp.108.121798] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2008] [Accepted: 05/23/2008] [Indexed: 05/18/2023]
Affiliation(s)
- Erik Nielsen
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109, USA
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168
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Bassham DC, Blatt MR. SNAREs: cogs and coordinators in signaling and development. PLANT PHYSIOLOGY 2008; 147:1504-15. [PMID: 18678742 PMCID: PMC2492632 DOI: 10.1104/pp.108.121129] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2008] [Accepted: 05/14/2008] [Indexed: 05/18/2023]
Affiliation(s)
- Diane C Bassham
- Department of Genetics, Development, and Cell Biology and Plant Sciences Institute, Iowa State University, Ames, Iowa 50011, USA.
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169
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Van Damme D, Inzé D, Russinova E. Vesicle trafficking during somatic cytokinesis. PLANT PHYSIOLOGY 2008; 147:1544-52. [PMID: 18678745 PMCID: PMC2492601 DOI: 10.1104/pp.108.120303] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Accepted: 05/29/2008] [Indexed: 05/24/2023]
Affiliation(s)
- Daniël Van Damme
- Department of Plant Systems Biology, Flanders Institute for Biotechnology, Ghent University, B-9052 Ghent, Belgium
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170
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Rojo E, Denecke J. What is moving in the secretory pathway of plants? PLANT PHYSIOLOGY 2008; 147:1493-503. [PMID: 18678741 PMCID: PMC2492647 DOI: 10.1104/pp.108.124552] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2008] [Accepted: 06/25/2008] [Indexed: 05/18/2023]
Affiliation(s)
- Enrique Rojo
- Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, E-28049 Madrid, Spain
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171
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Robinson DG, Langhans M, Saint-Jore-Dupas C, Hawes C. BFA effects are tissue and not just plant specific. TRENDS IN PLANT SCIENCE 2008; 13:405-8. [PMID: 18640067 DOI: 10.1016/j.tplants.2008.05.010] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2008] [Revised: 05/23/2008] [Accepted: 05/30/2008] [Indexed: 05/08/2023]
Abstract
Brefeldin A (BFA) is one of the most popular drugs used by researchers for studies on secretion and endocytosis because it interferes with specific vesicle coat proteins via action on a guanine nucleotide exchange factor. Due to its range of morphological effects on the Golgi apparatus in a variety of plant tissues, we believe that there is more to the BFA response than the primary molecular targets so far identified.
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Affiliation(s)
- David G Robinson
- Department of Cell Biology, Heidelberg Institute for Plant Sciences, University of Heidelberg, 69120 Heidelberg, Germany
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172
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Robinson DG, Jiang L, Schumacher K. The endosomal system of plants: charting new and familiar territories. PLANT PHYSIOLOGY 2008; 147:1482-92. [PMID: 18678740 PMCID: PMC2492610 DOI: 10.1104/pp.108.120105] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2008] [Accepted: 05/05/2008] [Indexed: 05/18/2023]
Affiliation(s)
- David G Robinson
- Heidelberg Institute of Plant Sciences, University of Heidelberg, 69120 Heidelberg, Germany
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173
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Held MA, Boulaflous A, Brandizzi F. Advances in fluorescent protein-based imaging for the analysis of plant endomembranes. PLANT PHYSIOLOGY 2008; 147:1469-81. [PMID: 18678739 PMCID: PMC2492624 DOI: 10.1104/pp.108.120147] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Affiliation(s)
- Michael A Held
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824-1312, USA
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174
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Abstract
Plant endosomes are highly dynamic organelles that are involved in the constitutive recycling of plasma membrane cargo and the trafficking of polarized plasma membrane proteins such as auxin carriers. In addition, recent studies have shown that surface receptors such as the plant defense-related FLS2 receptor and the brassinosteroid receptor BRI1 appear to signal from endosomes upon ligand binding and internalization. In yeast and mammals, endosomes are also known to recycle vacuolar cargo receptors back to the trans Golgi network and sort membrane proteins for degradation in the vacuole/lysosome. Some of these sorting mechanisms are mediated by the retromer and endosomal sorting complex required for transport (ESCRT) complexes. Plants contain orthologs of all major retromer and ESCRT complex subunits, but they have also evolved variations in endosomal functions connected to plant-specific features such as the diversity of vacuolar transport pathways. This review focuses on recent studies in plants dealing with the regulation of endosomal recycling functions, architecture and formation of multivesicular bodies, ligand-mediated endocytosis and receptor signaling from endosomes as well as novel endosomal markers and the function of endosomes in the transport and processing of soluble vacuolar proteins.
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Affiliation(s)
- Marisa S Otegui
- Department of Botany, University of Wisconsin-Madison, Madison, WI 53706, USA.
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175
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Foresti O, Denecke J. Intermediate organelles of the plant secretory pathway: identity and function. Traffic 2008; 9:1599-612. [PMID: 18627574 DOI: 10.1111/j.1600-0854.2008.00791.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The secretory pathway of eukaryotic cells comprises a network of organelles that connects three large membranes, the plasma membrane, the vacuole and the endoplasmic reticulum. The Golgi apparatus and the various post-Golgi organelles that control vacuolar sorting, secretion and endocytosis can be regarded as intermediate organelles of the endocytic and biosynthetic routes. Many processes in the secretory pathway have evolved differently in plants and cannot be studied using yeast or mammalian cells as models. The best characterized organelles are the Golgi apparatus and the prevacuolar compartment, but recent work has shed light on the role of the trans Golgi network, which has to be regarded as a separate organelle in plants. In this study, we wish to highlight recent findings regarding the late secretory pathway and its crosstalk with the early secretory pathway as well as the endocytic route in plants. Recently published findings and suggested models are discussed within the context of known features of the equivalent pathway in other eukaryotes.
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Affiliation(s)
- Ombretta Foresti
- Centre for Plant Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
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176
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Endosidin1 defines a compartment involved in endocytosis of the brassinosteroid receptor BRI1 and the auxin transporters PIN2 and AUX1. Proc Natl Acad Sci U S A 2008; 105:8464-9. [PMID: 18550817 DOI: 10.1073/pnas.0711650105] [Citation(s) in RCA: 202] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Although it is known that proteins are delivered to and recycled from the plasma membrane (PM) via endosomes, the nature of the compartments and pathways responsible for cargo and vesicle sorting and cellular signaling is poorly understood. To define and dissect specific recycling pathways, chemical effectors of proteins involved in vesicle trafficking, especially through endosomes, would be invaluable. Thus, we identified chemicals affecting essential steps in PM/endosome trafficking, using the intensely localized PM transport at the tips of germinating pollen tubes. The basic mechanisms of this localized growth are likely similar to those of non-tip growing cells in seedlings. The compound endosidin 1 (ES1) interfered selectively with endocytosis in seedlings, providing a unique tool to dissect recycling pathways. ES1 treatment induced the rapid agglomeration of the auxin translocators PIN2 and AUX1 and the brassinosteroid receptor BRI1 into distinct endomembrane compartments termed "endosidin bodies"; however, the markers PIN1, PIN7, and other PM proteins were unaffected. Endosidin bodies were defined by the syntaxin SYP61 and the V-ATPase subunit VHA-a1, two trans-Golgi network (TGN)/endosomal proteins. Interestingly, brassinosteroid (BR)-induced gene expression was inhibited by ES1 and treated seedlings displayed a brassinolide (BL)-insensitive phenotype similar to a bri1 loss-of-function mutant. No effect was detected in auxin signaling. Thus, PIN2, AUX1, and BRI1 use interactive pathways involving an early SYP61/VHA-a1 endosomal compartment.
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177
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Ishikawa T, Machida C, Yoshioka Y, Ueda T, Nakano A, Machida Y. EMBRYO YELLOW gene, encoding a subunit of the conserved oligomeric Golgi complex, is required for appropriate cell expansion and meristem organization in Arabidopsis thaliana. Genes Cells 2008; 13:521-35. [DOI: 10.1111/j.1365-2443.2008.01186.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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178
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Wang L, Liao FL, Zhu L, Peng XB, Sun MX. NtGNL1 is involved in embryonic cell division patterning, root elongation, and pollen tube growth in tobacco. THE NEW PHYTOLOGIST 2008; 179:81-93. [PMID: 18399932 DOI: 10.1111/j.1469-8137.2008.02444.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The function of the ARF-GEF family has drawn great attention recently, especially GNOM and GNL1, owing to their important role in plant development. A homolog of GBF was identified in Nicotiana tabacum, named NtGNL1, which is ubiquitously expressed throughout the tobacco life cycle. In NtGNL1 RNAi plants, irregular orientation of cell division and asynchronous cell development during early embryogenesis disrupted the symmetry of the developing embryo. In addition, root growth in transgenic lines was significantly slower than that in wild-type plants, although the structure of the root tip was largely intact. Pollen germination and pollen tube growth were also inhibited in the transgenic lines, and the tip of the pollen tube presented various aberrant morphologies in one of the transgenic lines. The phenotypes of different NtGNL1 RNAi transgenic lines suggest that the NtGNL1 is likely to be involved not only in embryogenesis and postembryonic development, but also in sexual reproduction; thus, NtGNL1 may play multiple and critical roles in plant development.
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Affiliation(s)
| | | | - Li Zhu
- Key Laboratory of Ministry of Education for Plant Developmental Biology, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Xiong-Bo Peng
- Key Laboratory of Ministry of Education for Plant Developmental Biology, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Meng-Xiang Sun
- Key Laboratory of Ministry of Education for Plant Developmental Biology, College of Life Sciences, Wuhan University, Wuhan 430072, China
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179
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Kong SG, Nagatani A. Where and how does phototropin transduce light signals in the cell? PLANT SIGNALING & BEHAVIOR 2008; 3:275-7. [PMID: 19704653 PMCID: PMC2634201 DOI: 10.4161/psb.3.4.5239] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2007] [Accepted: 11/05/2007] [Indexed: 05/22/2023]
Abstract
Light plays pivotal roles as an important environmental signal in plant growth and development. In Arabidopsis, phototropin 1 (phot1) and 2 (phot2) are the photoreceptors that mediate phototropism, chloroplast relocation, stomatal opening and leaf flattening, in response to blue light. However, little is known about how phototropins transduce the signals after the light is perceived. Changes induced by blue light in terms of intracellular localization patterns of phot2 in Arabidopsis were examined. Phot2 distributed uniformly in the plasma membrane under dark conditions. Upon irradiation with blue light, some of the phot2 associated with the Golgi apparatus. It was also shown that the kinase domain, but not the photosensory domain, is required for a plasma membrane and Golgi localization. Furthermore a kinase fragment, lacking the photosensory domain, constitutively triggered physiological responses in planta. Thus, the plasma membrane and the Golgi apparatus appear to be the most likely sites for the initial step of phot2 signal transduction. The Golgi apparatus facilitates vesicle trafficking and delivery of membrane proteins to the required locations in the cell. Therefore, this study implicates the regulation of vesicle trafficking by the Golgi apparatus as a mechanism by which phot2 elicits its cellular responses.
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Affiliation(s)
- Sam-Geun Kong
- Division of Photobiology; National Institute for Basic Biology; Okazaki, Japan
| | - Akira Nagatani
- Laboratory of Plant Physiology; Department of Botany; Graduate School of Science; Kyoto University; Kyoto, Japan
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180
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Berken A, Wittinghofer A. Structure and function of Rho-type molecular switches in plants. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2008; 46:380-93. [PMID: 18272378 DOI: 10.1016/j.plaphy.2007.12.008] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2007] [Indexed: 05/20/2023]
Abstract
Molecular switches of the Rho family, in concert with their associated regulators and effectors are well known as important control elements of vital signaling pathways in eucaryotic organisms. Yet, this knowledge has so far been established mainly from animal and fungal studies. However, during the recent years, the Rho switch has gone increasingly green as well, and it turned out that the homologous system in plants holds some distinctive features regarding structures, functions and molecular mechanisms for signal transduction. In this review, we give an overview about the structural characteristics of the Rho proteins of plants, termed ROP, highlighting some exciting differences to their animal and fungal counterparts. We further address the unique regulators and effectors of the ROPs and discuss the structural basis for the function and interaction of those proteins in ROP controlled reaction cascades. We finally intend to stimulate the demand for future three-dimensional structures that advance our understanding of the ROP switch in plants.
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Affiliation(s)
- Antje Berken
- Max Planck Institute of Molecular Physiology, Structural Biology Department, Otto Hahn Strasse 11, 44227 Dortmund, Germany.
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181
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Laxmi A, Pan J, Morsy M, Chen R. Light plays an essential role in intracellular distribution of auxin efflux carrier PIN2 in Arabidopsis thaliana. PLoS One 2008; 3:e1510. [PMID: 18231596 PMCID: PMC2200863 DOI: 10.1371/journal.pone.0001510] [Citation(s) in RCA: 184] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2007] [Accepted: 12/29/2007] [Indexed: 11/18/2022] Open
Abstract
Background Light plays a key role in multiple plant developmental processes. It has been shown that root development is modulated by shoot-localized light signaling and requires shoot-derived transport of the plant hormone, auxin. However, the mechanism by which light regulates root development is not largely understood. In plants, the endogenous auxin, indole-3-acetic acid, is directionally transported by plasma-membrane (PM)-localized auxin influx and efflux carriers in transporting cells. Remarkably, the auxin efflux carrier PIN proteins exhibit asymmetric PM localization, determining the polarity of auxin transport. Similar to PM-resident receptors and transporters in animal and yeast cells, PIN proteins undergo constitutive cycling between the PM and endosomal compartments. Auxin plays multiple roles in PIN protein intracellular trafficking, inhibiting PIN2 endocytosis at some concentrations and promoting PIN2 degradation at others. However, how PIN proteins are turned over in plant cells is yet to be addressed. Methodology and Principle Findings Using laser confocal scanning microscopy, and physiological and molecular genetic approaches, here, we show that in dark-grown seedlings, the PM localization of auxin efflux carrier PIN2 was largely reduced, and, in addition, PIN2 signal was detected in vacuolar compartments. This is in contrast to light-grown seedlings where PIN2 was predominantly PM-localized. In light-grown plants after shift to dark or to continuous red or far-red light, PIN2 also accumulated in vacuolar compartments. We show that PIN2 vacuolar targeting was derived from the PM via endocytic trafficking and inhibited by HY5-dependent light signaling. In addition, the ubiquitin 26S proteasome is involved in the process, since its inhibition by mutations in COP9 and a proteasome inhibitor MG132 impaired the process. Conclusions and Significance Collectively, our data indicate that light plays an essential role in PIN2 intracellular trafficking, promoting PM-localization in the presence of light and, on the other hand, vacuolar targeting for protein degradation in the absence of light. Based on these results, we postulate that light regulation of root development is mediated at least in part by changes in the intracellular distribution of auxin efflux carriers, PIN proteins, in response to the light environment.
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Affiliation(s)
- Ashverya Laxmi
- Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, Oklahoma, United States of America
| | - Jianwei Pan
- Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, Oklahoma, United States of America
| | - Mustafa Morsy
- Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, Oklahoma, United States of America
| | - Rujin Chen
- Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, Oklahoma, United States of America
- * To whom correspondence should be addressed. E-mail:
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182
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Golomb L, Abu-Abied M, Belausov E, Sadot E. Different subcellular localizations and functions of Arabidopsis myosin VIII. BMC PLANT BIOLOGY 2008; 8:3. [PMID: 18179725 PMCID: PMC2275265 DOI: 10.1186/1471-2229-8-3] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2007] [Accepted: 01/08/2008] [Indexed: 05/18/2023]
Abstract
BACKGROUND Myosins are actin-activated ATPases that use energy to generate force and move along actin filaments, dragging with their tails different cargos. Plant myosins belong to the group of unconventional myosins and Arabidopsis myosin VIII gene family contains four members: ATM1, ATM2, myosin VIIIA and myosin VIIIB. RESULTS In transgenic plants expressing GFP fusions with ATM1 (IQ-tail truncation, lacking the head domain), fluorescence was differentially distributed: while in epidermis cells at the root cap GFP-ATM1 equally distributed all over the cell, in epidermal cells right above this region it accumulated in dots. Further up, in cells of the elongation zone, GFP-ATM1 was preferentially positioned at the sides of transversal cell walls. Interestingly, the punctate pattern was insensitive to brefeldin A (BFA) while in some cells closer to the root cap, ATM1 was found in BFA bodies. With the use of different markers and transient expression in Nicotiana benthamiana leaves, it was found that myosin VIII co-localized to the plasmodesmata and ER, colocalized with internalized FM4-64, and partially overlapped with the endosomal markers ARA6, and rarely with ARA7 and FYVE. Motility of ARA6 labeled organelles was inhibited whenever associated with truncated ATM1 but motility of FYVE labeled organelles was inhibited only when associated with large excess of ATM1. Furthermore, GFP-ATM1 and RFP-ATM2 (IQ-tail domain) co-localized to the same spots on the plasma membrane, indicating a specific composition at these sites for myosin binding. CONCLUSION Taken together, our data suggest that myosin VIII functions differently in different root cells and can be involved in different steps of endocytosis, BFA-sensitive and insensitive pathways, ER tethering and plasmodesmatal activity.
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Affiliation(s)
- Lior Golomb
- The Institute of Plant Sciences, The Volcani Center, Bet-Dagan 50250, Israel
| | - Mohamad Abu-Abied
- The Institute of Plant Sciences, The Volcani Center, Bet-Dagan 50250, Israel
| | - Eduard Belausov
- The Institute of Plant Sciences, The Volcani Center, Bet-Dagan 50250, Israel
| | - Einat Sadot
- The Institute of Plant Sciences, The Volcani Center, Bet-Dagan 50250, Israel
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183
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Chow CM, Neto H, Foucart C, Moore I. Rab-A2 and Rab-A3 GTPases define a trans-golgi endosomal membrane domain in Arabidopsis that contributes substantially to the cell plate. THE PLANT CELL 2008; 20:101-23. [PMID: 18239134 PMCID: PMC2254926 DOI: 10.1105/tpc.107.052001] [Citation(s) in RCA: 215] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2007] [Revised: 12/10/2007] [Accepted: 01/13/2008] [Indexed: 05/18/2023]
Abstract
The Ypt3/Rab11/Rab25 subfamily of Rab GTPases has expanded greatly in Arabidopsis thaliana, comprising 26 members in six provisional subclasses, Rab-A1 to Rab-A6. We show that the Rab-A2 and Rab-A3 subclasses define a novel post-Golgi membrane domain in Arabidopsis root tips. The Rab-A2/A3 compartment was distinct from but often close to Golgi stacks and prevacuolar compartments and partly overlapped the VHA-a1 trans-Golgi compartment. It was also sensitive to brefeldin A and accumulated FM4-64 before prevacuolar compartments did. Mutations in RAB-A2a that were predicted to stabilize the GDP- or GTP-bound state shifted the location of the protein to the Golgi or plasma membrane, respectively. In mitosis, KNOLLE accumulated principally in the Rab-A2/A3 compartment. During cytokinesis, Rab-A2 and Rab-A3 proteins localized precisely to the growing margins of the cell plate, but VHA-a1, GNOM, and prevacuolar markers were excluded. Inducible expression of dominant-inhibitory mutants of RAB-A2a resulted in enlarged, polynucleate, meristematic cells with cell wall stubs. The Rab-A2/A3 compartment, therefore, is a trans-Golgi compartment that communicates with the plasma membrane and early endosomal system and contributes substantially to the cell plate. Despite the unique features of plant cytokinesis, membrane traffic to the division plane exhibits surprising molecular similarity across eukaryotic kingdoms in its reliance on Ypt3/Rab11/Rab-A GTPases.
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Affiliation(s)
- Cheung-Ming Chow
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom
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184
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Guermonprez H, Smertenko A, Crosnier MT, Durandet M, Vrielynck N, Guerche P, Hussey PJ, Satiat-Jeunemaitre B, Bonhomme S. The POK/AtVPS52 protein localizes to several distinct post-Golgi compartments in sporophytic and gametophytic cells. JOURNAL OF EXPERIMENTAL BOTANY 2008; 59:3087-98. [PMID: 18583349 DOI: 10.1093/jxb/ern162] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The organization and dynamics of the plant endomembrane system require both universal and plant-specific molecules and compartments. The latter, despite the growing wealth of information, remains poorly understood. From the study of an Arabidopsis thaliana male gametophytic mutant, it was possible to isolate a gene named POKY POLLEN TUBE (POK) essential for pollen tube tip growth. The similarity between the predicted POK protein sequence and yeast Vps52p, a subunit from the GARP/VFT complex which is involved in the docking of vesicles from the prevacuolar compartment to the Golgi apparatus, suggested that the POK protein plays a role in plant membrane trafficking. Genetic analysis of Arabidopsis mutants affecting AtVPS53 or AtVPS54 genes which encode putative POK partners shows a transmission defect through the male gametophyte for all lines, which is similar to the pok mutant. Using a combination of biochemical approaches and specific antiserum it has been demonstrated that the POK protein is present in phylogenetically divergent plant species, associated with membranes and belongs to a high molecular weight complex. Combination of immunolocalization studies and pharmacological approaches in different plant cells revealed that the POK protein associates with Golgi and post-Golgi compartments. The role of POK in post-Golgi endomembrane trafficking and as a member of a putative plant GARP/VFT complex is discussed.
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Affiliation(s)
- Hélène Guermonprez
- INRA UR254, Station de Génétique et d'Amélioration des Plantes, Institut Jean-Pierre Bourgin, Centre de Versailles-Grignon, F-78026 Versailles, France
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185
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ARF1 is directly involved in dynamin-independent endocytosis. Nat Cell Biol 2007; 10:30-41. [PMID: 18084285 DOI: 10.1038/ncb1666] [Citation(s) in RCA: 161] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2007] [Accepted: 11/29/2007] [Indexed: 12/20/2022]
Abstract
Endocytosis of glycosylphosphatidyl inositol (GPI)-anchored proteins (GPI-APs) and the fluid phase takes place primarily through a dynamin- and clathrin-independent, Cdc42-regulated pinocytic mechanism. This mechanism is mediated by primary carriers called clathrin-independent carriers (CLICs), which fuse to form tubular early endocytic compartments called GPI-AP enriched endosomal compartments (GEECs). Here, we show that reduction in activity or levels of ARF1 specifically inhibits GPI-AP and fluid-phase endocytosis without affecting other clathrin-dependent or independent endocytic pathways. ARF1 is activated at distinct sites on the plasma membrane, and by the recruitment of RhoGAP domain-containing protein, ARHGAP10, to the plasma membrane, modulates cell-surface Cdc42 dynamics. This results in the coupling of ARF1 and Cdc42 activity to regulate endocytosis at the plasma membrane. These findings provide a molecular basis for a crosstalk of endocytosis with secretion by the sharing of a key regulator of secretory traffic, ARF1.
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186
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Plant Cytokinesis Requires De Novo Secretory Trafficking but Not Endocytosis. Curr Biol 2007; 17:2047-53. [DOI: 10.1016/j.cub.2007.10.040] [Citation(s) in RCA: 149] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2007] [Revised: 10/15/2007] [Accepted: 10/16/2007] [Indexed: 01/04/2023]
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187
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Jaillais Y, Gaude T. Sorting out the sorting functions of endosomes in Arabidopsis. PLANT SIGNALING & BEHAVIOR 2007; 2:556-8. [PMID: 19704558 PMCID: PMC2634368 DOI: 10.4161/psb.2.6.5108] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2007] [Accepted: 10/04/2007] [Indexed: 05/02/2023]
Abstract
In animals, sorting of membrane proteins following their internalization from the plasma membrane (PM) by endocytosis occurs through a series of different endosomal compartments. In plants, how and where these sorting events take place is still poorly understood and our current view of the endocytic pathway still largely relies on analogies made from the animal system. However, extensive differences seem to exist between animal and plant endosomal functions, as exemplified by the role of the trans-Golgi network (TGN) as an early endosomal compartment in plants or the functional diversification of conserved sorting complexes. By using the Arabidopsis root tip as a reference model, we and other have begun to shed light on the complexity of the plant endocytic pathways. Notably, we have recently characterized the functions of an endosomal compartment, the SNX1-endosomes, also referred to as the prevacuolar compartment (PVC) or multivesicular bodies (MVB), in the sorting of different cargo proteins, including two related auxin-efflux carriers, PIN1 and PIN2. We have shown that routing decisions take place at this endosomal level, such as the sorting of PIN2 toward the lytic vacuole for degradation or PIN1 toward the PM for recycling.
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Affiliation(s)
- Yvon Jaillais
- Reproduction et Développement des Plantes; Institut Fédératif de Recherche 128; Centre National de la Recherche Scientifique; Institut National de la Recherche Agronomique; Université Claude Bernard Lyon I; Ecole Normale Supérieure de Lyon; Lyon, France
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188
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Lam SK, Tse YC, Robinson DG, Jiang L. Tracking down the elusive early endosome. TRENDS IN PLANT SCIENCE 2007; 12:497-505. [PMID: 17920331 DOI: 10.1016/j.tplants.2007.09.001] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2007] [Revised: 08/14/2007] [Accepted: 09/25/2007] [Indexed: 05/25/2023]
Abstract
Despite significant progress in understanding protein trafficking and compartmentation in plants, the identification and protein compartmentalization for organelles that belong to both the secretory and endocytic pathways have been difficult because protein trafficking has generally been studied separately in these two pathways. However, recent data indicate that the trans-Golgi network serves as an early endosome merging the secretory and endocytic pathways in plant cells. Here, we discuss the proteins identified as markers for post-Golgi compartments in these two pathways and propose that the trans-Golgi network is a pivotal organelle with multiple sorting domains for post-Golgi protein trafficking in plant cells.
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Affiliation(s)
- Sheung Kwan Lam
- Department of Biology and Molecular Biotechnology Program, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Yu Chung Tse
- Department of Biology and Molecular Biotechnology Program, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - David G Robinson
- Department of Cell Biology, Heidelberg Institute for Plant Sciences, University of Heidelberg, D-69120 Heidelberg, Germany
| | - Liwen Jiang
- Department of Biology and Molecular Biotechnology Program, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
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189
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Richter S, Geldner N, Schrader J, Wolters H, Stierhof YD, Rios G, Koncz C, Robinson DG, Jürgens G. Functional diversification of closely related ARF-GEFs in protein secretion and recycling. Nature 2007; 448:488-92. [PMID: 17653190 DOI: 10.1038/nature05967] [Citation(s) in RCA: 164] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2007] [Accepted: 05/30/2007] [Indexed: 11/08/2022]
Abstract
Guanine-nucleotide exchange factors on ADP-ribosylation factor GTPases (ARF-GEFs) regulate vesicle formation in time and space by activating ARF substrates on distinct donor membranes. Mammalian GBF1 (ref. 2) and yeast Gea1/2 (ref. 3) ARF-GEFs act at Golgi membranes, regulating COPI-coated vesicle formation. In contrast, their Arabidopsis thaliana homologue GNOM (GN) is required for endosomal recycling, playing an important part in development. This difference indicates an evolutionary divergence of trafficking pathways between animals and plants, and raised the question of how endoplasmic reticulum-Golgi transport is regulated in plants. Here we demonstrate that the closest homologue of GNOM in Arabidopsis, GNOM-LIKE1 (GNL1; NM_123312; At5g39500), performs this ancestral function. GNL1 localizes to and acts primarily at Golgi stacks, regulating COPI-coated vesicle formation. Surprisingly, GNOM can functionally substitute for GNL1, but not vice versa. Our results suggest that large ARF-GEFs of the GBF1 class perform a conserved role in endoplasmic reticulum-Golgi trafficking and secretion, which is done by GNL1 and GNOM in Arabidopsis, whereas GNOM has evolved to perform an additional plant-specific function of recycling from endosomes to the plasma membrane. Duplication and diversification of ARF-GEFs in plants contrasts with the evolution of entirely new classes of ARF-GEFs for endosomal trafficking in animals, which illustrates the independent evolution of complex endosomal pathways in the two kingdoms.
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