1
|
Liu Q, Vain T, Viotti C, Doyle SM, Tarkowská D, Novák O, Zipfel C, Sitbon F, Robert S, Hofius D. Vacuole Integrity Maintained by DUF300 Proteins Is Required for Brassinosteroid Signaling Regulation. Mol Plant 2018; 11:553-567. [PMID: 29288738 DOI: 10.1016/j.molp.2017.12.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Revised: 11/21/2017] [Accepted: 12/18/2017] [Indexed: 06/07/2023]
Abstract
Brassinosteroid (BR) hormone signaling controls multiple processes during plant growth and development and is initiated at the plasma membrane through the receptor kinase BRASSINOSTEROID INSENSITIVE1 (BRI1) together with co-receptors such as BRI1-ASSOCIATED RECEPTOR KINASE1 (BAK1). BRI1 abundance is regulated by endosomal recycling and vacuolar targeting, but the role of vacuole-related proteins in BR receptor dynamics and BR responses remains elusive. Here, we show that the absence of two DUF300 domain-containing tonoplast proteins, LAZARUS1 (LAZ1) and LAZ1 HOMOLOG1 (LAZ1H1), causes vacuole morphology defects, growth inhibition, and constitutive activation of BR signaling. Intriguingly, tonoplast accumulation of BAK1 was substantially increased and appeared causally linked to enhanced BRI1 trafficking and degradation in laz1 laz1h1 plants. Since unrelated vacuole mutants exhibited normal BR responses, our findings indicate that DUF300 proteins play distinct roles in the regulation of BR signaling by maintaining vacuole integrity required to balance subcellular BAK1 pools and BR receptor distribution.
Collapse
Affiliation(s)
- Qinsong Liu
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences (SLU) and Linnean Center for Plant Biology, PO Box 7080, 750 07 Uppsala, Sweden
| | - Thomas Vain
- Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences (SLU), 90183 Umeå, Sweden
| | - Corrado Viotti
- Umeå Plant Science Centre, Umeå University, 90187 Umeå, Sweden; Institute of Biochemistry and Biology, Plant Physiology, University of Potsdam, 14476 Potsdam, Germany
| | - Siamsa M Doyle
- Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences (SLU), 90183 Umeå, Sweden
| | - Danuše Tarkowská
- Laboratory of Growth Regulators, Centre of the Region Haná for Biotechnological and Agricultural Research, Institute of Experimental Botany ASCR and Palacký University, 783 71 Olomouc, Czech Republic
| | - Ondřej Novák
- Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences (SLU), 90183 Umeå, Sweden; Laboratory of Growth Regulators, Centre of the Region Haná for Biotechnological and Agricultural Research, Institute of Experimental Botany ASCR and Palacký University, 783 71 Olomouc, Czech Republic
| | - Cyril Zipfel
- The Sainsbury Laboratory, Norwich Research Park, Norwich NR4 7UH, UK
| | - Folke Sitbon
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences (SLU) and Linnean Center for Plant Biology, PO Box 7080, 750 07 Uppsala, Sweden
| | - Stéphanie Robert
- Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences (SLU), 90183 Umeå, Sweden
| | - Daniel Hofius
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences (SLU) and Linnean Center for Plant Biology, PO Box 7080, 750 07 Uppsala, Sweden.
| |
Collapse
|
2
|
Robinson DG, Hawes C, Hillmer S, Jürgens G, Schwechheimer C, Stierhof YD, Viotti C. Auxin and Vesicle Traffic. Plant Physiol 2018; 176:1884-1888. [PMID: 29630496 PMCID: PMC5841702 DOI: 10.1104/pp.17.01510] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Affiliation(s)
- David G Robinson
- Centre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany
| | - Chris Hawes
- Plant Cell Biology, Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, United Kingdom
| | - Stefan Hillmer
- Electron Microscopy Core Facility, University of Heidelberg, D-69120 Heidelberg, Germany
| | - Gerd Jürgens
- Center for Plant Molecular Biology, University of Tuebingen, D-72076 Tuebingen, Germany
| | - Claus Schwechheimer
- Plant Systems Biology, Technical University of Munich, D-85354 Freising, Germany
| | - York-Dieter Stierhof
- Center for Plant Molecular Biology, University of Tuebingen, D-72076 Tuebingen, Germany
| | - Corrado Viotti
- Institut de Biologie Moléculaire des Plantes, CNRS, 67084 Strasbourg, France
| |
Collapse
|
3
|
Nakamura M, Claes AR, Grebe T, Hermkes R, Viotti C, Ikeda Y, Grebe M. Auxin and ROP GTPase Signaling of Polar Nuclear Migration in Root Epidermal Hair Cells. Plant Physiol 2018; 176:378-391. [PMID: 29084900 PMCID: PMC5761770 DOI: 10.1104/pp.17.00713] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 10/26/2017] [Indexed: 05/25/2023]
Abstract
Polar nuclear migration is crucial during the development of diverse eukaryotes. In plants, root hair growth requires polar nuclear migration into the outgrowing hair. However, knowledge about the dynamics and the regulatory mechanisms underlying nuclear movements in root epidermal cells remains limited. Here, we show that both auxin and Rho-of-Plant (ROP) signaling modulate polar nuclear position at the inner epidermal plasma membrane domain oriented to the cortical cells during cell elongation as well as subsequent polar nuclear movement to the outer domain into the emerging hair bulge in Arabidopsis (Arabidopsis thaliana). Auxin signaling via the nuclear AUXIN RESPONSE FACTOR7 (ARF7)/ARF19 and INDOLE ACETIC ACID7 pathway ensures correct nuclear placement toward the inner membrane domain. Moreover, precise inner nuclear placement relies on SPIKE1 Rho-GEF, SUPERCENTIPEDE1 Rho-GDI, and ACTIN7 (ACT7) function and to a lesser extent on VTI11 vacuolar SNARE activity. Strikingly, the directionality and/or velocity of outer polar nuclear migration into the hair outgrowth along actin strands also are ACT7 dependent, auxin sensitive, and regulated by ROP signaling. Thus, our findings provide a founding framework revealing auxin and ROP signaling of inner polar nuclear position with some contribution by vacuolar morphology and of actin-dependent outer polar nuclear migration in root epidermal hair cells.
Collapse
Affiliation(s)
- Moritaka Nakamura
- Institute of Biochemistry and Biology, Plant Physiology, University of Potsdam, D-14476 Potsdam-Golm, Germany
| | - Andrea R Claes
- Institute of Biochemistry and Biology, Plant Physiology, University of Potsdam, D-14476 Potsdam-Golm, Germany
| | - Tobias Grebe
- Institute of Biochemistry and Biology, Plant Physiology, University of Potsdam, D-14476 Potsdam-Golm, Germany
| | - Rebecca Hermkes
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, SE-90 187 Umeå, Sweden
| | - Corrado Viotti
- Institute of Biochemistry and Biology, Plant Physiology, University of Potsdam, D-14476 Potsdam-Golm, Germany
| | - Yoshihisa Ikeda
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, SE-90 187 Umeå, Sweden
| | - Markus Grebe
- Institute of Biochemistry and Biology, Plant Physiology, University of Potsdam, D-14476 Potsdam-Golm, Germany
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, SE-90 187 Umeå, Sweden
| |
Collapse
|
4
|
Majda M, Grones P, Sintorn IM, Vain T, Milani P, Krupinski P, Zagórska-Marek B, Viotti C, Jönsson H, Mellerowicz EJ, Hamant O, Robert S. Mechanochemical Polarization of Contiguous Cell Walls Shapes Plant Pavement Cells. Dev Cell 2017; 43:290-304.e4. [DOI: 10.1016/j.devcel.2017.10.017] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Revised: 10/03/2017] [Accepted: 10/11/2017] [Indexed: 12/13/2022]
|
5
|
Mao H, Nakamura M, Viotti C, Grebe M. A Framework for Lateral Membrane Trafficking and Polar Tethering of the PEN3 ATP-Binding Cassette Transporter. Plant Physiol 2016; 172:2245-2260. [PMID: 27803190 PMCID: PMC5129716 DOI: 10.1104/pp.16.01252] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 10/31/2016] [Indexed: 05/18/2023]
Abstract
The outermost cell layer of plants, the epidermis, and its outer (lateral) membrane domain facing the environment are continuously challenged by biotic and abiotic stresses. Therefore, the epidermis and the outer membrane domain provide important selective and protective barriers. However, only a small number of specifically outer membrane-localized proteins are known. Similarly, molecular mechanisms underlying the trafficking and the polar placement of outer membrane domain proteins require further exploration. Here, we demonstrate that ACTIN7 (ACT7) mediates trafficking of the PENETRATION3 (PEN3) outer membrane protein from the trans-Golgi network (TGN) to the plasma membrane in the root epidermis of Arabidopsis (Arabidopsis thaliana) and that actin function contributes to PEN3 endocytic recycling. In contrast to such generic ACT7-dependent trafficking from the TGN, the EXOCYST84b (EXO84b) tethering factor mediates PEN3 outer-membrane polarity. Moreover, precise EXO84b placement at the outer membrane domain itself requires ACT7 function. Hence, our results uncover spatially and mechanistically distinct requirements for ACT7 function during outer lateral membrane cargo trafficking and polarity establishment. They further identify an exocyst tethering complex mediator of outer lateral membrane cargo polarity.
Collapse
Affiliation(s)
- Hailiang Mao
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, SE-90 187 Umeå, Sweden (H.M., M.G.); and
- Institute of Biochemistry and Biology, Plant Physiology, University of Potsdam, 14476 Potsdam-Golm, Germany (M.N., C.V., M.G.)
| | - Moritaka Nakamura
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, SE-90 187 Umeå, Sweden (H.M., M.G.); and
- Institute of Biochemistry and Biology, Plant Physiology, University of Potsdam, 14476 Potsdam-Golm, Germany (M.N., C.V., M.G.)
| | - Corrado Viotti
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, SE-90 187 Umeå, Sweden (H.M., M.G.); and
- Institute of Biochemistry and Biology, Plant Physiology, University of Potsdam, 14476 Potsdam-Golm, Germany (M.N., C.V., M.G.)
| | - Markus Grebe
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, SE-90 187 Umeå, Sweden (H.M., M.G.); and
- Institute of Biochemistry and Biology, Plant Physiology, University of Potsdam, 14476 Potsdam-Golm, Germany (M.N., C.V., M.G.)
| |
Collapse
|
6
|
Dejonghe W, Kuenen S, Mylle E, Vasileva M, Keech O, Viotti C, Swerts J, Fendrych M, Ortiz-Morea FA, Mishev K, Delang S, Scholl S, Zarza X, Heilmann M, Kourelis J, Kasprowicz J, Nguyen LSL, Drozdzecki A, Van Houtte I, Szatmári AM, Majda M, Baisa G, Bednarek SY, Robert S, Audenaert D, Testerink C, Munnik T, Van Damme D, Heilmann I, Schumacher K, Winne J, Friml J, Verstreken P, Russinova E. Mitochondrial uncouplers inhibit clathrin-mediated endocytosis largely through cytoplasmic acidification. Nat Commun 2016; 7:11710. [PMID: 27271794 PMCID: PMC4899852 DOI: 10.1038/ncomms11710] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Accepted: 04/21/2016] [Indexed: 11/27/2022] Open
Abstract
ATP production requires the establishment of an electrochemical proton gradient across the inner mitochondrial membrane. Mitochondrial uncouplers dissipate this proton gradient and disrupt numerous cellular processes, including vesicular trafficking, mainly through energy depletion. Here we show that Endosidin9 (ES9), a novel mitochondrial uncoupler, is a potent inhibitor of clathrin-mediated endocytosis (CME) in different systems and that ES9 induces inhibition of CME not because of its effect on cellular ATP, but rather due to its protonophore activity that leads to cytoplasm acidification. We show that the known tyrosine kinase inhibitor tyrphostinA23, which is routinely used to block CME, displays similar properties, thus questioning its use as a specific inhibitor of cargo recognition by the AP-2 adaptor complex via tyrosine motif-based endocytosis signals. Furthermore, we show that cytoplasm acidification dramatically affects the dynamics and recruitment of clathrin and associated adaptors, and leads to reduction of phosphatidylinositol 4,5-biphosphate from the plasma membrane. Plant cells maintain strict proton gradients over different membranes. Here, Dejonghe et al. show that several protonophores, including the known tyrosine kinase inhibitor TyrphostinA23, inhibit clathrin-mediated endocytosis by disturbing these gradients and causing cytoplasmic acidification.
Collapse
Affiliation(s)
- Wim Dejonghe
- Department of Plant Systems Biology, VIB, 9052 Gent, Belgium.,Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium
| | - Sabine Kuenen
- VIB Center for the Biology of Disease, Laboratory of Neuronal Communication, 3000 Leuven, Belgium.,Department for Human Genetics, and Leuven Institute for Neurodegenerative Diseases, KU Leuven, 3000 Leuven, Belgium
| | - Evelien Mylle
- Department of Plant Systems Biology, VIB, 9052 Gent, Belgium.,Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium
| | - Mina Vasileva
- Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria
| | - Olivier Keech
- Department of Plant Physiology, Umeå Plant Science Centre, Umeå University, 90187 Umeå, Sweden
| | - Corrado Viotti
- Department of Plant Physiology, Institute of Biochemistry and Biology, University of Potsdam, 14476 Potsdam, Germany
| | - Jef Swerts
- VIB Center for the Biology of Disease, Laboratory of Neuronal Communication, 3000 Leuven, Belgium.,Department for Human Genetics, and Leuven Institute for Neurodegenerative Diseases, KU Leuven, 3000 Leuven, Belgium
| | - Matyáš Fendrych
- Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria
| | - Fausto Andres Ortiz-Morea
- Department of Plant Systems Biology, VIB, 9052 Gent, Belgium.,Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium
| | - Kiril Mishev
- Department of Plant Systems Biology, VIB, 9052 Gent, Belgium.,Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium
| | - Simon Delang
- Developmental Biology of Plants, Centre for Organismal Studies, Heidelberg University, 69120 Heidelberg, Germany
| | - Stefan Scholl
- Developmental Biology of Plants, Centre for Organismal Studies, Heidelberg University, 69120 Heidelberg, Germany
| | - Xavier Zarza
- Department of Plant Cell Biology, Swammerdam Institute for Life Sciences, University of Amsterdam, 1090 GE Amsterdam, The Netherlands
| | - Mareike Heilmann
- Department of Cellular Biochemistry, Institute for Biochemistry and Biotechnology, Martin-Luther-University, 06120 Halle, Germany
| | - Jiorgos Kourelis
- Department of Plant Cell Biology, Swammerdam Institute for Life Sciences, University of Amsterdam, 1090 GE Amsterdam, The Netherlands
| | - Jaroslaw Kasprowicz
- VIB Center for the Biology of Disease, Laboratory of Neuronal Communication, 3000 Leuven, Belgium.,Department for Human Genetics, and Leuven Institute for Neurodegenerative Diseases, KU Leuven, 3000 Leuven, Belgium
| | | | | | - Isabelle Van Houtte
- Department of Plant Systems Biology, VIB, 9052 Gent, Belgium.,Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium
| | - Anna-Mária Szatmári
- Department of Plant Systems Biology, VIB, 9052 Gent, Belgium.,Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium
| | - Mateusz Majda
- Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden
| | - Gary Baisa
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | | | - Stéphanie Robert
- Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden
| | | | - Christa Testerink
- Department of Plant Cell Biology, Swammerdam Institute for Life Sciences, University of Amsterdam, 1090 GE Amsterdam, The Netherlands
| | - Teun Munnik
- Department of Plant Cell Biology, Swammerdam Institute for Life Sciences, University of Amsterdam, 1090 GE Amsterdam, The Netherlands
| | - Daniël Van Damme
- Department of Plant Systems Biology, VIB, 9052 Gent, Belgium.,Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium
| | - Ingo Heilmann
- Department of Cellular Biochemistry, Institute for Biochemistry and Biotechnology, Martin-Luther-University, 06120 Halle, Germany
| | - Karin Schumacher
- Developmental Biology of Plants, Centre for Organismal Studies, Heidelberg University, 69120 Heidelberg, Germany
| | - Johan Winne
- Laboratory for Organic Synthesis, Department of Organic and Macromolecular Chemistry, Ghent University, 9000 Gent, Belgium
| | - Jiří Friml
- Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria
| | - Patrik Verstreken
- VIB Center for the Biology of Disease, Laboratory of Neuronal Communication, 3000 Leuven, Belgium.,Department for Human Genetics, and Leuven Institute for Neurodegenerative Diseases, KU Leuven, 3000 Leuven, Belgium
| | - Eugenia Russinova
- Department of Plant Systems Biology, VIB, 9052 Gent, Belgium.,Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium
| |
Collapse
|
7
|
Olins AL, Langhans M, Monestier M, Schlotterer A, Robinson DG, Viotti C, Zentgraf H, Zwerger M, Olins DE. An epichromatin epitope: Persistence in the cell cycle and conservation in evolution. Nucleus 2014. [DOI: 10.4161/nucl.13655] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
|
8
|
Abstract
The endoplasmic reticulum (ER) represents the gateway for intracellular trafficking of membrane proteins, soluble cargoes and lipids. In all eukaryotes, the best described mechanism of exiting the ER is via COPII-coated vesicles, which transport both membrane proteins and soluble cargoes to the cis-Golgi. The vacuole, together with the plasma membrane, is the most distal point of the secretory pathway, and many vacuolar proteins are transported from the ER through intermediate compartments. However, past results and recent findings demonstrate the presence of alternative transport routes from the ER towards the tonoplast, which are independent of Golgi- and post-Golgi trafficking. Moreover, the transport mechanism of the vacuolar proton pumps VHA-a3 and AVP1 challenges the current model of vacuole biogenesis, pointing to the endoplasmic reticulum for being the main membrane source for the biogenesis of the plant lytic compartment. This review gives an overview of the current knowledge on the transport routes towards the vacuole and discusses the possible mechanism of vacuole biogenesis in plants.
Collapse
Affiliation(s)
- Corrado Viotti
- *Correspondence: Corrado Viotti, Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, Linnéusväg 6, 90187 Umeå, Sweden e-mail:
| |
Collapse
|
9
|
Viotti C, Krüger F, Krebs M, Neubert C, Fink F, Lupanga U, Scheuring D, Boutté Y, Frescatada-Rosa M, Wolfenstetter S, Sauer N, Hillmer S, Grebe M, Schumacher K. The endoplasmic reticulum is the main membrane source for biogenesis of the lytic vacuole in Arabidopsis. Plant Cell 2013; 25:3434-49. [PMID: 24014545 PMCID: PMC3809542 DOI: 10.1105/tpc.113.114827] [Citation(s) in RCA: 135] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Revised: 08/13/2013] [Accepted: 08/21/2013] [Indexed: 05/18/2023]
Abstract
Vacuoles are multifunctional organelles essential for the sessile lifestyle of plants. Despite their central functions in cell growth, storage, and detoxification, knowledge about mechanisms underlying their biogenesis and associated protein trafficking pathways remains limited. Here, we show that in meristematic cells of the Arabidopsis thaliana root, biogenesis of vacuoles as well as the trafficking of sterols and of two major tonoplast proteins, the vacuolar H(+)-pyrophosphatase and the vacuolar H(+)-adenosinetriphosphatase, occurs independently of endoplasmic reticulum (ER)-Golgi and post-Golgi trafficking. Instead, both pumps are found in provacuoles that structurally resemble autophagosomes but are not formed by the core autophagy machinery. Taken together, our results suggest that vacuole biogenesis and trafficking of tonoplast proteins and lipids can occur directly from the ER independent of Golgi function.
Collapse
Affiliation(s)
- Corrado Viotti
- Centre for Organismal Studies, Plant Developmental Biology, University of Heidelberg, 69120 Heidelberg, Germany
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, 90187 Umea, Sweden
| | - Falco Krüger
- Centre for Organismal Studies, Plant Developmental Biology, University of Heidelberg, 69120 Heidelberg, Germany
| | - Melanie Krebs
- Centre for Organismal Studies, Plant Developmental Biology, University of Heidelberg, 69120 Heidelberg, Germany
| | - Christoph Neubert
- Centre for Organismal Studies, Plant Developmental Biology, University of Heidelberg, 69120 Heidelberg, Germany
| | - Fabian Fink
- Centre for Organismal Studies, Plant Developmental Biology, University of Heidelberg, 69120 Heidelberg, Germany
| | - Upendo Lupanga
- Centre for Organismal Studies, Plant Developmental Biology, University of Heidelberg, 69120 Heidelberg, Germany
| | - David Scheuring
- Centre for Organismal Studies, Plant Developmental Biology, University of Heidelberg, 69120 Heidelberg, Germany
| | - Yohann Boutté
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, 90187 Umea, Sweden
| | - Márcia Frescatada-Rosa
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, 90187 Umea, Sweden
| | - Susanne Wolfenstetter
- Molecular Plant Physiology, University of Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Norbert Sauer
- Molecular Plant Physiology, University of Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Stefan Hillmer
- Centre for Organismal Studies, Plant Developmental Biology, University of Heidelberg, 69120 Heidelberg, Germany
| | - Markus Grebe
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, 90187 Umea, Sweden
| | - Karin Schumacher
- Centre for Organismal Studies, Plant Developmental Biology, University of Heidelberg, 69120 Heidelberg, Germany
- Address correspondence to
| |
Collapse
|
10
|
Viotti C, Dutykh D, Dudley JM, Dias F. Emergence of coherent wave groups in deep-water random sea. Phys Rev E Stat Nonlin Soft Matter Phys 2013; 87:063001. [PMID: 23848766 DOI: 10.1103/physreve.87.063001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Indexed: 06/02/2023]
Abstract
Extreme surface waves in a deep-water long-crested sea are often interpreted as a manifestation in the real world of the so-called breathing solitons of the focusing nonlinear Schrödinger equation. While the spontaneous emergence of such coherent structures from nonlinear wave dynamics was demonstrated to take place in fiber-optics systems, the same point remains far more controversial in the hydrodynamic case. With the aim to shed further light on this matter, the emergence of breatherlike coherent wave groups in a long-crested random sea is investigated here by means of high-resolution spectral simulations of the fully nonlinear two-dimensional Euler equations. The primary focus of our study is to parametrize the structure of random wave fields with respect to the Benjamin-Feir index, which is a nondimensional measure of the energy localization in Fourier space. This choice is motivated by previous results, showing that extreme-wave activity in a long-crested sea is highly sensitive to such a parameter, which is varied here by changing both the characteristic spectral bandwidth and the average wave steepness. It is found that coherent wave groups, closely matching realizations of Kuznetsov-Ma breathers in Euler dynamics, develop within wave fields characterized by sufficiently narrow-banded spectra. The characteristic spatial and temporal scales of wave group dynamics, and the corresponding occurrence of extreme events, are quantified and discussed by means of space-time autocorrelations of the surface elevation envelope and extreme-event statistics.
Collapse
Affiliation(s)
- C Viotti
- School of Mathematical Sciences, University College Dublin, Dublin, Ireland
| | | | | | | |
Collapse
|
11
|
Stierhof YD, Viotti C, Scheuring D, Sturm S, Robinson DG. Sorting nexins 1 and 2a locate mainly to the TGN. Protoplasma 2013; 250:235-40. [PMID: 22447127 DOI: 10.1007/s00709-012-0399-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 03/14/2012] [Indexed: 05/26/2023]
Abstract
The subcellular localization of the sorting nexins (SNXs) in higher plants is a matter of controversy. Previous confocal laser scanning microscopy (CLSM studies on root cells from a transgenic Arabidopsis line expressing SNX1-GFP have suggested that this SNX is present on an endosome having characteristics of both the trans-Golgi network (TGN) and the multivesicular body (MVB). In contrast, SNX2a locates exclusively to the TGN when transiently expressed in tobacco mesophyll protoplasts. By performing immunogold electron microscopy on cryofixed Arabidopsis roots, we have tried to clarify the situation. Both SNX1-GFP and endogenous SNX2a locate principally to the TGN. Labeling of MVBs could not be confirmed with any certainty.
Collapse
Affiliation(s)
- York-Dieter Stierhof
- Microscopy, Centre for Plant Molecular Biology, University of Tübingen, 72076 Tübingen, Germany
| | | | | | | | | |
Collapse
|
12
|
Krüger F, Krebs M, Viotti C, Langhans M, Schumacher K, Robinson DG. PDMP induces rapid changes in vacuole morphology in Arabidopsis root cells. J Exp Bot 2013; 64:529-40. [PMID: 23230024 PMCID: PMC3542044 DOI: 10.1093/jxb/ers345] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
PDMP (D-L-threo-1-phenyl-2-decanoyl amino-3-morpholino-1-propanol) is a well-known inhibitor of glucosylceramide synthase (GCS), a key enzyme in sphingolipid biosynthesis. Through the resultant increase in ceramides which interact with mTOR and Beclin1 (Atg6), this drug is also known to induce macroautophagy in mammalian cells. This study investigated the response of Arabidopsis root cells to PDMP, and what are probably numerous tightly packed small vacuoles in the control cells appear to fuse to form a single globular-shaped vacuole. However, during this fusion process, cytoplasm channels between the individual vacuoles become trapped in deep invaginations of the tonoplast. In both optical sections in the confocal laser scanning microscope and in ultrathin sections in the electron microscope, these invaginations have the appearance of cytoplasmic inclusions in the vacuole lumen. These changes in vacuole morphology are rapid (occurring within minutes after application of PDMP) and are independent of ongoing protein synthesis. The tonoplast invaginations remain visible for hours, but after 24h almost all disappear. Experiments designed to examine whether ceramide levels might be the cause of the PDMP effect have not proved conclusive. On the other hand, this study has been able to rule out the release of Ca(2+) ions from intracellular stores as a contributing factor.
Collapse
Affiliation(s)
- Falco Krüger
- Department of Plant Developmental Biology, Centre for Organismal Studies, University of Heidelberg, Heidelberg, Germany
- * These authors contributed equally to this manuscript.
| | - Melanie Krebs
- Department of Plant Developmental Biology, Centre for Organismal Studies, University of Heidelberg, Heidelberg, Germany
- * These authors contributed equally to this manuscript.
| | - Corrado Viotti
- Department of Plant Developmental Biology, Centre for Organismal Studies, University of Heidelberg, Heidelberg, Germany
| | - Markus Langhans
- Department of Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, Heidelberg, Germany
| | - Karin Schumacher
- Department of Plant Developmental Biology, Centre for Organismal Studies, University of Heidelberg, Heidelberg, Germany
| | - David G. Robinson
- Department of Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, Heidelberg, Germany
- * These authors contributed equally to this manuscript.
| |
Collapse
|
13
|
Scheuring D, Künzl F, Viotti C, Yan MSW, Jiang L, Schellmann S, Robinson DG, Pimpl P. Ubiquitin initiates sorting of Golgi and plasma membrane proteins into the vacuolar degradation pathway. BMC Plant Biol 2012; 12:164. [PMID: 22970698 PMCID: PMC3534617 DOI: 10.1186/1471-2229-12-164] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Accepted: 07/13/2012] [Indexed: 05/18/2023]
Abstract
BACKGROUND In yeast and mammals, many plasma membrane (PM) proteins destined for degradation are tagged with ubiquitin. These ubiquitinated proteins are internalized into clathrin-coated vesicles and are transported to early endosomal compartments. There, ubiquitinated proteins are sorted by the endosomal sorting complex required for transport (ESCRT) machinery into the intraluminal vesicles of multivesicular endosomes. Degradation of these proteins occurs after endosomes fuse with lysosomes/lytic vacuoles to release their content into the lumen. In plants, some PM proteins, which cycle between the PM and endosomal compartments, have been found to be ubiquitinated, but it is unclear whether ubiquitin is sufficient to mediate internalization and thus acts as a primary sorting signal for the endocytic pathway. To test whether plants use ubiquitin as a signal for the degradation of membrane proteins, we have translationally fused ubiquitin to different fluorescent reporters for the plasma membrane and analyzed their transport. RESULTS Ubiquitin-tagged PM reporters localized to endosomes and to the lumen of the lytic vacuole in tobacco mesophyll protoplasts and in tobacco epidermal cells. The internalization of these reporters was significantly reduced if clathrin-mediated endocytosis was inhibited by the coexpression of a mutant of the clathrin heavy chain, the clathrin hub. Surprisingly, a ubiquitin-tagged reporter for the Golgi was also transported into the lumen of the vacuole. Vacuolar delivery of the reporters was abolished upon inhibition of the ESCRT machinery, indicating that the vacuolar delivery of these reporters occurs via the endocytic transport route. CONCLUSIONS Ubiquitin acts as a sorting signal at different compartments in the endomembrane system to target membrane proteins into the vacuolar degradation pathway: If displayed at the PM, ubiquitin triggers internalization of PM reporters into the endocytic transport route, but it also mediates vacuolar delivery if displayed at the Golgi. In both cases, ubiquitin-tagged proteins travel via early endosomes and multivesicular bodies to the lytic vacuole. This suggests that vacuolar degradation of ubiquitinated proteins is not restricted to PM proteins but might also facilitate the turnover of membrane proteins in the early secretory pathway.
Collapse
Affiliation(s)
- David Scheuring
- Department of Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, Heidelberg, 69120, Germany
| | - Fabian Künzl
- Department of Developmental Genetics, Center for Plant Molecular Biology (ZMBP), University of Tübingen, Tübingen, 72076, Germany
| | - Corrado Viotti
- Department of Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, Heidelberg, 69120, Germany
- Plant Developmental Biology, Centre for Organismal Studies, University of Heidelberg, Heidelberg, 69120, Germany
| | - Melody San Wan Yan
- School of Life Sciences, Centre for Cell and Developmental Biology, The Chinese University of Hong Kong, Shatin NT, Hong Kong, PR China
| | - Liwen Jiang
- School of Life Sciences, Centre for Cell and Developmental Biology, The Chinese University of Hong Kong, Shatin NT, Hong Kong, PR China
| | - Swen Schellmann
- Botanical Institute, Biozentrum Köln, University of Cologne, Cologne, 50674, Germany
| | - David G Robinson
- Department of Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, Heidelberg, 69120, Germany
| | - Peter Pimpl
- Department of Developmental Genetics, Center for Plant Molecular Biology (ZMBP), University of Tübingen, Tübingen, 72076, Germany
- Department of Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, Heidelberg, 69120, Germany
| |
Collapse
|
14
|
Robinson DG, Pimpl P, Scheuring D, Stierhof YD, Sturm S, Viotti C. Trying to make sense of retromer. Trends Plant Sci 2012; 17:431-9. [PMID: 22502774 DOI: 10.1016/j.tplants.2012.03.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Revised: 03/13/2012] [Accepted: 03/15/2012] [Indexed: 05/08/2023]
Abstract
Retromer is a cytosolic protein complex which binds to post-Golgi organelles involved in the trafficking of proteins to the lytic compartment of the cell. In non-plant organisms, retromer mediates the recycling of acid hydrolase receptors from early endosomal (EE) compartments. In plants, retromer components are required for the targeting of vacuolar storage proteins, and for the recycling of endocytosed PIN proteins. However, there are contradictory reports as to the localization of the sorting nexins and the core subunit of retromer. There is also uncertainty as to the identity of the organelles from which vacuolar sorting receptors (VSRs) and endocytosed plasma membrane (PM) proteins are recycled. In this review we try to resolve some of these conflicting observations.
Collapse
Affiliation(s)
- David G Robinson
- Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany.
| | | | | | | | | | | |
Collapse
|
15
|
Hillmer S, Viotti C, Robinson DG. An improved procedure for low-temperature embedding of high-pressure frozen and freeze-substituted plant tissues resulting in excellent structural preservation and contrast. J Microsc 2012; 247:43-7. [PMID: 22360578 DOI: 10.1111/j.1365-2818.2011.03595.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Here we describe refinements in the processing of high-pressure frozen samples of delicate plant tissues for immuno-electron microscopy. These involve: shortened freeze-substitution schedules, lower temperatures during processing and polymerisation, the avoidance of temperature fluctuations and the optimisation of heat transfer from the specimens using small disposable aluminium containers. The application of these modifications leads to very good structural preservation and selective membrane contrast. As a result, the versatility of the method is increased since not only immuno-electron microscopical studies can be performed but often the quality is also quite suitable for structural investigations.
Collapse
Affiliation(s)
- S Hillmer
- Department of Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, Heidelberg, Germany.
| | | | | |
Collapse
|
16
|
Scheuring D, Viotti C, Krüger F, Künzl F, Sturm S, Bubeck J, Hillmer S, Frigerio L, Robinson DG, Pimpl P, Schumacher K. Multivesicular bodies mature from the trans-Golgi network/early endosome in Arabidopsis. Plant Cell 2011; 23:3463-81. [PMID: 21934143 PMCID: PMC3203422 DOI: 10.1105/tpc.111.086918] [Citation(s) in RCA: 197] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2011] [Revised: 08/19/2011] [Accepted: 08/31/2011] [Indexed: 05/17/2023]
Abstract
The plant trans-Golgi network/early endosome (TGN/EE) is a major hub for secretory and endocytic trafficking with complex molecular mechanisms controlling sorting and transport of cargo. Vacuolar transport from the TGN/EE to multivesicular bodies/late endosomes (MVBs/LEs) is assumed to occur via clathrin-coated vesicles, although direct proof for their participation is missing. Here, we present evidence that post-TGN transport toward lytic vacuoles occurs independently of clathrin and that MVBs/LEs are derived from the TGN/EE through maturation. We show that the V-ATPase inhibitor concanamycin A significantly reduces the number of MVBs and causes TGN and MVB markers to colocalize in Arabidopsis thaliana roots. Ultrastructural analysis reveals the formation of MVBs from the TGN/EE and their fusion with the vacuole. The localization of the ESCRT components VPS28, VPS22, and VPS2 at the TGN/EE and MVBs/LEs indicates that the formation of intraluminal vesicles starts already at the TGN/EE. Accordingly, a dominant-negative mutant of VPS2 causes TGN and MVB markers to colocalize and blocks vacuolar transport. RNA interference-mediated knockdown of the annexin ANNAT3 also yields the same phenotype. Together, these data indicate that MVBs originate from the TGN/EE in a process that requires the action of ESCRT for the formation of intraluminal vesicles and annexins for the final step of releasing MVBs as a transport carrier to the vacuole.
Collapse
Affiliation(s)
- David Scheuring
- Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, 69120 Heidelberg, Germany
| | - Corrado Viotti
- Developmental Biology of Plants, Centre for Organismal Studies, University of Heidelberg, 69120 Heidelberg, Germany
| | - Falco Krüger
- Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, 69120 Heidelberg, Germany
| | - Fabian Künzl
- Developmental Genetics, Centre for Plant Molecular Biology, University of Tübingen, 72076 Tuebingen, Germany
| | - Silke Sturm
- Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, 69120 Heidelberg, Germany
| | - Julia Bubeck
- Developmental Biology of Plants, Centre for Organismal Studies, University of Heidelberg, 69120 Heidelberg, Germany
| | - Stefan Hillmer
- Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, 69120 Heidelberg, Germany
| | - Lorenzo Frigerio
- Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - David G. Robinson
- Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, 69120 Heidelberg, Germany
| | - Peter Pimpl
- Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, 69120 Heidelberg, Germany
- Developmental Genetics, Centre for Plant Molecular Biology, University of Tübingen, 72076 Tuebingen, Germany
- Address correspondence to
| | - Karin Schumacher
- Developmental Biology of Plants, Centre for Organismal Studies, University of Heidelberg, 69120 Heidelberg, Germany
| |
Collapse
|
17
|
Olins AL, Langhans M, Monestier M, Schlotterer A, Robinson DG, Viotti C, Zentgraf H, Zwerger M, Olins DE. An epichromatin epitope: Persistence in the cell cycle and conservation in evolution. Nucleus 2011. [DOI: 10.4161/nucl.2.1.13655] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
|
18
|
Olins AL, Langhans M, Monestier M, Schlotterer A, Robinson DG, Viotti C, Zentgraf H, Zwerger M, Olins DE. An epichromatin epitope: persistence in the cell cycle and conservation in evolution. Nucleus 2011; 2:47-60. [PMID: 21647299 PMCID: PMC3104809 DOI: 10.4161/nucl.2.1.13271] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2010] [Revised: 09/15/2010] [Accepted: 09/16/2010] [Indexed: 11/19/2022] Open
Abstract
Interphase nuclear architecture is disrupted and rapidly reformed with each cell division cycle. Successive cell generations exhibit a "memory" of this nuclear architecture, as well as for gene expression. Furthermore, many features of nuclear and mitotic chromosome structure are recognizably species and tissue specific. We wish to know what properties of the underlying chromatin structure may determine these conserved features of nuclear architecture. Employing a particular mouse autoimmune anti-nucleosome monoclonal antibody (PL2-6), combined with deconvolution immunofluorescence microscopy, we present evidence for a unique epitope (involving a ternary complex of histones H2A and H2B and DNA) which is localized only at the exterior chromatin surface of interphase nuclei and mitotic chromosomes in mammalian, invertebrate and plant systems. As only the surface chromatin region is identified with antibody PL2-6, we have assigned it the name "epichromatin". We describe an "epichromatin hypothesis", suggesting that epichromatin may have a unique evolutionary conserved conformation which facilitates interaction with the reforming post-mitotic nuclear envelope and a rapid return of interphase nuclear architecture.
Collapse
Affiliation(s)
- Ada L Olins
- Department of Pharmaceutical Sciences, College of Pharmacy, University of New England, Portland, ME USA. ted proteins (ARPs), a
| | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Schott A, Ravaud S, Keller S, Radzimanowski J, Viotti C, Hillmer S, Sinning I, Strahl S. Arabidopsis stromal-derived Factor2 (SDF2) is a crucial target of the unfolded protein response in the endoplasmic reticulum. J Biol Chem 2010; 285:18113-21. [PMID: 20378538 DOI: 10.1074/jbc.m110.117176] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Stresses increasing the load of unfolded proteins that enter the endoplasmic reticulum (ER) trigger a protective response termed the unfolded protein response (UPR). Stromal cell-derived factor2 (SDF2)-type proteins are highly conserved throughout the plant and animal kingdoms. In this study we have characterized AtSDF2 as crucial component of the UPR in Arabidopsis thaliana. Using a combination of biochemical and cell biological methods, we demonstrate that SDF2 is induced in response to ER stress conditions causing the accumulation of unfolded proteins. Transgenic reporter plants confirmed induction of SDF2 during ER stress. Under normal growth conditions SDF2 is highly expressed in fast growing, differentiating cells and meristematic tissues. The increased production of SDF2 due to ER stress and in tissues that require enhanced protein biosynthesis and secretion, and its association with the ER membrane qualifies SDF2 as a downstream target of the UPR. Determination of the SDF2 three-dimensional crystal structure at 1.95 A resolution revealed the typical beta-trefoil fold with potential carbohydrate binding sites. Hence, SDF2 might be involved in the quality control of glycoproteins. Arabidopsis sdf2 mutants display strong defects and morphological phenotypes during seedling development specifically under ER stress conditions, thus establishing that SDF2-type proteins play a key role in the UPR.
Collapse
Affiliation(s)
- Andrea Schott
- Department of Cell Chemistry, Institute for Plant Sciences, Im Neuenheimer Feld 360, University of Heidelberg, D-69120 Heidelberg, Germany
| | | | | | | | | | | | | | | |
Collapse
|
20
|
Viotti C, Bubeck J, Stierhof YD, Krebs M, Langhans M, van den Berg W, van Dongen W, Richter S, Geldner N, Takano J, Jürgens G, de Vries SC, Robinson DG, Schumacher K. Endocytic and secretory traffic in Arabidopsis merge in the trans-Golgi network/early endosome, an independent and highly dynamic organelle. Plant Cell 2010; 22:1344-57. [PMID: 20435907 PMCID: PMC2879741 DOI: 10.1105/tpc.109.072637] [Citation(s) in RCA: 340] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2009] [Revised: 03/22/2010] [Accepted: 04/09/2010] [Indexed: 05/17/2023]
Abstract
Plants constantly adjust their repertoire of plasma membrane proteins that mediates transduction of environmental and developmental signals as well as transport of ions, nutrients, and hormones. The importance of regulated secretory and endocytic trafficking is becoming increasingly clear; however, our knowledge of the compartments and molecular machinery involved is still fragmentary. We used immunogold electron microscopy and confocal laser scanning microscopy to trace the route of cargo molecules, including the BRASSINOSTEROID INSENSITIVE1 receptor and the REQUIRES HIGH BORON1 boron exporter, throughout the plant endomembrane system. Our results provide evidence that both endocytic and secretory cargo pass through the trans-Golgi network/early endosome (TGN/EE) and demonstrate that cargo in late endosomes/multivesicular bodies is destined for vacuolar degradation. Moreover, using spinning disc microscopy, we show that TGN/EEs move independently and are only transiently associated with an individual Golgi stack.
Collapse
Affiliation(s)
- Corrado Viotti
- Department of Cell Biology, Heidelberg Institute for Plant Sciences, University of Heidelberg, 69120 Heidelberg, Germany
| | - Julia Bubeck
- Department of Developmental Biology, Heidelberg Institute for Plant Sciences, University of Heidelberg, 69120 Heidelberg, Germany
| | - York-Dieter Stierhof
- Microscopy Unit, Center for Plant Molecular Biology, University of Tübingen, 72076 Tübingen, Germany
| | - Melanie Krebs
- Department of Developmental Biology, Heidelberg Institute for Plant Sciences, University of Heidelberg, 69120 Heidelberg, Germany
| | - Markus Langhans
- Department of Cell Biology, Heidelberg Institute for Plant Sciences, University of Heidelberg, 69120 Heidelberg, Germany
| | - Willy van den Berg
- Laboratory of Biochemistry, Wageningen University, 6703 HA Wageningen, The Netherlands
| | - Walter van Dongen
- Laboratory of Biochemistry, Wageningen University, 6703 HA Wageningen, The Netherlands
| | - Sandra Richter
- Developmental Genetics, Center for Plant Molecular Biology, University of Tübingen, 72076 Tübingen, Germany
| | - Niko Geldner
- Department of Plant Molecular Biology, University of Lausanne, 1015 Lausanne, Switzerland
| | - Junpei Takano
- Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Sapporo 060-8589, Japan
| | - Gerd Jürgens
- Developmental Genetics, Center for Plant Molecular Biology, University of Tübingen, 72076 Tübingen, Germany
| | - Sacco C. de Vries
- Laboratory of Biochemistry, Wageningen University, 6703 HA Wageningen, The Netherlands
| | - David G. Robinson
- Department of Cell Biology, Heidelberg Institute for Plant Sciences, University of Heidelberg, 69120 Heidelberg, Germany
| | - Karin Schumacher
- Department of Developmental Biology, Heidelberg Institute for Plant Sciences, University of Heidelberg, 69120 Heidelberg, Germany
- Address correspondence to
| |
Collapse
|
21
|
Niemes S, Langhans M, Viotti C, Scheuring D, San Wan Yan M, Jiang L, Hillmer S, Robinson DG, Pimpl P. Retromer recycles vacuolar sorting receptors from the trans-Golgi network. Plant J 2010; 61:107-21. [PMID: 19796370 DOI: 10.1111/j.1365-313x.2009.04034.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Receptor-mediated sorting processes in the secretory pathway of eukaryotic cells rely on mechanisms to recycle the receptors after completion of transport. Based on this principle, plant vacuolar sorting receptors (VSRs) are thought to recycle after dissociating of receptor-ligand complexes in a pre-vacuolar compartment. This recycling is mediated by retromer, a cytosolic coat complex that comprises sorting nexins and a large heterotrimeric subunit. To analyse retromer-mediated VSR recycling, we have used a combination of immunoelectron and fluorescence microscopy to localize the retromer components sorting nexin 1 (SNX1) and sorting nexin 2a (SNX2a) and the vacuolar sorting protein VPS29p. All retromer components localize to the trans-Golgi network (TGN), which is considered to represent the early endosome of plants. In addition, we show that inhibition of retromer function in vivo by expression of SNX1 or SNX2a mutants as well as transient RNAi knockdown of all sorting nexins led to accumulation of the VSR BP80 at the TGN. Quantitative protein transport studies and live-cell imaging using fluorescent vacuolar cargo molecules revealed that arrival of these VSR ligands at the vacuole is not affected under these conditions. Based on these findings, we propose that the TGN is the location of retromer-mediated recycling of VSRs, and that transport towards the lytic vacuole downstream of the TGN is receptor-independent and occurs via maturation, similar to transition of the early endosome into the late endosome in mammalian cells.
Collapse
Affiliation(s)
- Silke Niemes
- Department of Cell Biology, Heidelberg Institute for Plant Sciences, University of Heidelberg, Germany
| | | | | | | | | | | | | | | | | |
Collapse
|
22
|
Bubeck J, Scheuring D, Hummel E, Langhans M, Viotti C, Foresti O, Denecke J, Banfield DK, Robinson DG. The syntaxins SYP31 and SYP81 control ER-Golgi trafficking in the plant secretory pathway. Traffic 2008; 9:1629-52. [PMID: 18764818 DOI: 10.1111/j.1600-0854.2008.00803.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Overexpression of the Golgi and endoplasmic reticulum (ER) syntaxins SYP31 and SYP81 strongly inhibits constitutive secretion. By comparing the secreted reporter alpha-amylase with the ER-retained reporter alpha-amylase-HDEL, it was concluded that SYP81 overexpression inhibits both retrograde and anterograde transport, while SYP31 overexpression mainly affected anterograde transport. Of the other interacting SNAREs investigated, only the overexpression of MEMB11 led to an inhibition of protein secretion. Although the position of a fluorescent tag does not influence the correct localization of the fusion protein, only N-terminal-tagged SYP31 retained the ability of the untagged SNARE to inhibit transport. C-terminal-tagged SYP31 failed to exhibit this effect. Overexpression of both wild-type and N-terminal-tagged syntaxins caused standard Golgi marker proteins to redistribute into the ER. Nevertheless, green fluorescent protein (GFP)-SYP31 was still visible as fluorescent punctae, which, unlike SYP31-GFP, were resistant to brefeldin A treatment. Immunogold electron microscopy showed that endogenous SYP81 is not only present at the ER but also in the cis Golgi, indicating that this syntaxin cycles between these two organelles. However, when expressed at non-inhibitory levels, YFP-SYP81 was seen to locate principally to subdomains of the ER. These punctate structures were physically separated from the Golgi, suggesting that they might possibly reflect the position of ER import sites.
Collapse
Affiliation(s)
- Julia Bubeck
- Department of Cell Biology, Heidelberg Institute for Plant Sciences, University of Heidelberg, Heidelberg, Germany
| | | | | | | | | | | | | | | | | |
Collapse
|
23
|
Dolfini S, Consonni G, Viotti C, Dal Prà M, Saltini G, Giulini A, Pilu R, Malgioglio A, Gavazzi G. A mutational approach to the study of seed development in maize. J Exp Bot 2007; 58:1197-205. [PMID: 17244631 DOI: 10.1093/jxb/erl290] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The maize seed comprises two major compartments, the embryo and the endosperm, both originating from the double fertilization event. The embryogenetic process allows the formation of a well-differentiated embryonic axis, surrounded by a single massive cotyledon, the scutellum. The mature endosperm constitutes the bulk of the seed and comprises specific regions containing reserve proteins, complex carbohydrates, and oils. To gain more insight into molecular events that underlie seed development, three monogenic mutants were characterized, referred to as emp (empty pericarp) on the basis of their extreme endosperm reduction, first recognizable at about 12 d after pollination. Their histological analysis reveals a partial development of the endosperm domains as well as loss of adhesion between pedicel tissues and the basal transfer layer. In the endosperm, programmed cell death (PCD) is delayed. The embryo appears retarded in its growth, but not impaired in its morphogenesis. The mutants can be rescued by culturing immature embryos, even though the seedlings appear retarded in their growth. The analysis of seeds with discordant embryo-endosperm phenotype (mutant embryo, normal endosperm and vice-versa), obtained using B-A translocations, suggests that emp expression in the embryo is necessary, but not sufficient, for proper seed development. In all three mutants the picture emerging is one of a general delay in processes related to growth, as a result of a mutation affecting endosperm development as a primary event.
Collapse
Affiliation(s)
- Silvana Dolfini
- Dipartimento di Scienze Biomolecolari e Biotecnologie, Università degli Studi di Milano, Via Celoria 26, 20133 Milano, Italia
| | | | | | | | | | | | | | | | | |
Collapse
|
24
|
Viotti C, Luoni L, Morandini P, De Michelis MI. Characterization of the interaction between the plasma membrane H-ATPase of Arabidopsis thaliana and a novel interactor (PPI1). FEBS J 2005; 272:5864-71. [PMID: 16279950 DOI: 10.1111/j.1742-4658.2005.04985.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Proton pump interactor, isoform 1 (PPI1) is a novel interactor of the C-terminus of Arabidopsis thaliana plasma membrane H(+)-ATPase (EC 3.6.3.6). We produced two fusion proteins consisting of, respectively, the first 88 amino acids or the entire protein deleted of the last 24 hydrophobic amino acids, and we show that the latter protein has a threefold higher affinity for the H(+)-ATPase. PPI1-induced stimulation of H(+)-ATPase activity dramatically decreased with the increase of pH above pH 6.8, but became largely pH-independent when the enzyme C-terminus was displaced by fusicoccin-induced binding of 14-3-3 proteins. The latter treatment did not affect PPI1 affinity for the H(+)-ATPase. These results indicate that PPI1 can bind the H(+)-ATPase independently of the C-terminus conformation, but is not able to suppress the C-terminus auto-inhibitory action.
Collapse
Affiliation(s)
- Corrado Viotti
- Dipartimento di Biologia 'L. Gorini', Università di Milano, CNR Istituto di Biofisica -- Sezione di Milano, Italy
| | | | | | | |
Collapse
|
25
|
Fenoglio D, Li Pira G, De Berardinis P, Saverino D, Terranova MP, Ombra MN, Bracci L, Lozzi L, Viotti C, Guardiola J, Manca F. Antagonistic activity of HIV-1 T helper peptides flanked by an unrelated carrier protein. Eur J Immunol 1999; 29:1448-55. [PMID: 10359098 DOI: 10.1002/(sici)1521-4141(199905)29:05<1448::aid-immu1448>3.0.co;2-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Antagonism is the ability of a modified antigenic peptide (altered peptide ligand, APL) to prevent CD4 T cell activation by the original peptide. Here we show that antagonistic activity can be conferred to peptides of HIV envelope glycoprotein gp120 and reverse transcriptase p66 by adding flanking polypeptide sequences at the C or at the N terminus by genetic engineering, rather than by introducing substitutions by synthesis. The glutathione S-transferase (GST)-peptide system has been used to produce molecules that display the peptide at the appropriate end of the GST carrier. When the gp120 peptide 191-205 (pep24) was expressed at the C terminus of GST (GST-24), antigenicity of specific human CD4 T cells was maintained. In contrast, when the peptide was expressed at the N terminus of GST (24-GST), antigenicity was abolished and antagonistic activity was introduced. Similar results were obtained with a p66-derived peptide at the C terminus of the GST carrier. Antagonism was (1) specific; proliferation of a CD4 T cell line from the same donor responding to the envelope glycoprotein of another retrovirus, HTLV-1, was not affected; (2) reversible; proliferative response was rescued in T cells exposed to antigen-presenting cells (APC) pulsed with the antagonist; (3) dominant; T cells cultured with APC pulsed with the agonist and with APC pulsed with the antagonist did not proliferate. The carrier could be cleaved by proteolysis while the antagonistic activity was preserved. Thus a minimal sequence that confers antagonistic activity can be engineered or synthesized with peptides to antagonize undesired CD4 responses as an alternative to the use of APL.
Collapse
Affiliation(s)
- D Fenoglio
- Department of Immunology, San Martino Hospital, University of Genoa, Italy
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
26
|
Viotti C. [Electronic identification of slides in dentistry]. Riv Ital Odontotec 1984; 20:73-4. [PMID: 6598873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
|
27
|
Viotti C. [New possibilities for intra-oral traction]. Riv Ital Odontotec 1984; 20:77-9. [PMID: 6598872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
|
28
|
Viotti C. [Problems with positioners]. Riv Ital Odontotec 1984; 20:57-60. [PMID: 6597491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
|