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Tumor Extracellular Vesicles Regulate Macrophage-Driven Metastasis through CCL5. Cancers (Basel) 2021; 13:cancers13143459. [PMID: 34298673 PMCID: PMC8303898 DOI: 10.3390/cancers13143459] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 07/02/2021] [Accepted: 07/04/2021] [Indexed: 11/16/2022] Open
Abstract
Simple Summary About 10–20 percent of patients with breast cancer are diagnosed with triple-negative breast cancer (TNBC). These tumors are named for their lack of expression of estrogen receptor (ER), progesterone receptor (PR), and amplification of human epidermal growth factor receptor 2 (HER2). These genes are targeted by therapies in other breast cancer patients. However, most TNBC patients recur within 5 years. Understanding how and why these tumors metastasize will help clinicians better treat these underserved cancer patients. TNBC tumors are highly infiltrated by tumor-associated macrophages (TAMs) that promote tumorigenesis and metastasis. Our study elucidates how the tumor co-opts macrophages recruited to the tumor through extracellular vesicles (EVs), further increasing tumor metastasis. Expression of tumor CCL5 regulates EV secretion and cargo that further alters macrophage phenotype to drive tumor metastasis. Together, our data suggest a more extensive role of EVs in the biology of tumor metastasis as well as their potential use as biomarkers. Abstract Purpose: To understand how tumor cells alter macrophage biology once they are recruited to triple-negative breast cancer (TNBC) tumors by CCL5. Method: Mouse bone marrow derived macrophage (BMDMs) were isolated and treated with recombinant CCL5 protein alone, with tumor cell conditioned media, or with tumor extracellular vesicles (EVs). Media from these tumor EV-educated macrophages (TEMs) was then used to determine how these macrophages affect TNBC invasion. To understand the mechanism, we assayed the cytokine secretion from these macrophages to determine how they impact tumor cell invasion. Tumor CCL5 expression was varied in tumors to determine its role in regulating macrophage biology through EVs. Results: Tumor EVs are a necessary component for programming naïve macrophages toward a pro-metastatic phenotype. CCL5 expression in the tumor cells regulates both EV biogenesis/secretion/cargo and macrophage EV-education toward a pro-metastatic phenotype. Analysis of the tumor EV-educated macrophages (TEMs) showed secretion of a variety of factors including CXCL1, CTLA-4, IFNG, OPN, HGF, TGFB, and CCL19 capable of remodeling the surrounding tumor stroma and immune infiltrate. Injection of tumor cells with macrophages educated by metastatic tumor cell EVs into mice increased tumor metastasis to the lung. Conclusion: These results demonstrate that tumor-derived EVs are key mediators of macrophage education and likely play a more complex role in modulating tumor therapeutic response by regulating the tumor immune infiltrate.
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Scali M, Moscatelli A, Bini L, Onelli E, Vignani R, Wang W. Protein Analysis of Pollen Tubes after the Treatments of Membrane Trafficking Inhibitors Gains Insights on Molecular Mechanism Underlying Pollen Tube Polar Growth. Protein J 2021; 40:205-222. [PMID: 33751342 PMCID: PMC8019430 DOI: 10.1007/s10930-021-09972-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/19/2021] [Indexed: 12/03/2022]
Abstract
Pollen tube elongation is characterized by a highly-polarized tip growth process dependent on an efficient vesicular transport system and largely mobilized by actin cytoskeleton. Pollen tubes are an ideal model system to study exocytosis, endocytosis, membrane recycling, and signaling network coordinating cellular processes, structural organization and vesicular trafficking activities required for tip growth. Proteomic analysis was applied to identify Nicotiana tabacum Differentially Abundant Proteins (DAPs) after in vitro pollen tube treatment with membrane trafficking inhibitors Brefeldin A, Ikarugamycin and Wortmannin. Among roughly 360 proteins separated in two-dimensional gel electrophoresis, a total of 40 spots visibly changing between treated and control samples were identified by MALDI-TOF MS and LC-ESI-MS/MS analysis. The identified proteins were classified according to biological processes, and most proteins were related to pollen tube energy metabolism, including ammino acid synthesis and lipid metabolism, structural features of pollen tube growth as well modification and actin cytoskeleton organization, stress response, and protein degradation. In-depth analysis of proteins corresponding to energy-related pathways revealed the male gametophyte to be a reliable model of energy reservoir and dynamics.
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Affiliation(s)
- Monica Scali
- Department of Life Sciences, University of Siena, Siena, Italy.
| | | | - Luca Bini
- Department of Life Sciences, University of Siena, Siena, Italy
| | | | - Rita Vignani
- Department of Life Sciences, University of Siena, Siena, Italy
| | - Wei Wang
- College of Life Sciences, Henan Agricultural University, Zhengzhou, China
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Park CJ, Wei T, Sharma R, Ronald PC. Overexpression of Rice Auxilin-Like Protein, XB21, Induces Necrotic Lesions, up-Regulates Endocytosis-Related Genes, and Confers Enhanced Resistance to Xanthomonas oryzae pv. oryzae. RICE (NEW YORK, N.Y.) 2017; 10:27. [PMID: 28577284 PMCID: PMC5457384 DOI: 10.1186/s12284-017-0166-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 05/24/2017] [Indexed: 05/29/2023]
Abstract
BACKGROUND The rice immune receptor XA21 confers resistance to the bacterial pathogen, Xanthomonas oryzae pv. oryzae (Xoo). To elucidate the mechanism of XA21-mediated immunity, we previously performed a yeast two-hybrid screening for XA21 interactors and identified XA21 binding protein 21 (XB21). RESULTS Here, we report that XB21 is an auxilin-like protein predicted to function in clathrin-mediated endocytosis. We demonstrate an XA21/XB21 in vivo interaction using co-immunoprecipitation in rice. Overexpression of XB21 in rice variety Kitaake and a Kitaake transgenic line expressing XA21 confers a necrotic lesion phenotype and enhances resistance to Xoo. RNA sequencing reveals that XB21 overexpression results in the differential expression of 8735 genes (4939 genes up- and 3846 genes down-regulated) (≥2-folds, FDR ≤0.01). The up-regulated genes include those predicted to be involved in 'cell death' and 'vesicle-mediated transport'. CONCLUSION These results indicate that XB21 plays a role in the plant immune response and in regulation of cell death. The up-regulation of genes controlling 'vesicle-mediated transport' in XB21 overexpression lines is consistent with a functional role for XB21 as an auxilin.
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Affiliation(s)
- Chang-Jin Park
- Department of Plant Pathology and the Genome Center, University of California Davis, Davis, CA, 95616, USA
- Department of Bioresources Engineering and the Plant Engineering Research Institute, Sejong University, Seoul, 05006, Republic of Korea
| | - Tong Wei
- Department of Plant Pathology and the Genome Center, University of California Davis, Davis, CA, 95616, USA
- Feedstocks Division, Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Rita Sharma
- Department of Plant Pathology and the Genome Center, University of California Davis, Davis, CA, 95616, USA
- School of Computational & Integrative Sciences, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Pamela C Ronald
- Department of Plant Pathology and the Genome Center, University of California Davis, Davis, CA, 95616, USA.
- Feedstocks Division, Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
- Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
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Osterrieder A, Sparkes IA, Botchway SW, Ward A, Ketelaar T, de Ruijter N, Hawes C. Stacks off tracks: a role for the golgin AtCASP in plant endoplasmic reticulum-Golgi apparatus tethering. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:3339-3350. [PMID: 28605454 PMCID: PMC5853478 DOI: 10.1093/jxb/erx167] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 04/25/2017] [Indexed: 05/18/2023]
Abstract
The plant Golgi apparatus modifies and sorts incoming proteins from the endoplasmic reticulum (ER) and synthesizes cell wall matrix material. Plant cells possess numerous motile Golgi bodies, which are connected to the ER by yet to be identified tethering factors. Previous studies indicated a role for cis-Golgi plant golgins, which are long coiled-coil domain proteins anchored to Golgi membranes, in Golgi biogenesis. Here we show a tethering role for the golgin AtCASP at the ER-Golgi interface. Using live-cell imaging, Golgi body dynamics were compared in Arabidopsis thaliana leaf epidermal cells expressing fluorescently tagged AtCASP, a truncated AtCASP-ΔCC lacking the coiled-coil domains, and the Golgi marker STtmd. Golgi body speed and displacement were significantly reduced in AtCASP-ΔCC lines. Using a dual-colour optical trapping system and a TIRF-tweezer system, individual Golgi bodies were captured in planta. Golgi bodies in AtCASP-ΔCC lines were easier to trap and the ER-Golgi connection was more easily disrupted. Occasionally, the ER tubule followed a trapped Golgi body with a gap, indicating the presence of other tethering factors. Our work confirms that the intimate ER-Golgi association can be disrupted or weakened by expression of truncated AtCASP-ΔCC and suggests that this connection is most likely maintained by a golgin-mediated tethering complex.
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Affiliation(s)
- Anne Osterrieder
- Department of Biological and Medical Sciences, Faculty of Health and Life Sciences, Oxford Brookes University, Gipsy Lane, Headington, Oxford, UK
| | - Imogen A Sparkes
- Department of Biological and Medical Sciences, Faculty of Health and Life Sciences, Oxford Brookes University, Gipsy Lane, Headington, Oxford, UK
| | - Stan W Botchway
- Central Laser Facility, Science and Technology Facilities Council, Research Complex at Harwell, Didcot, Oxon, UK
| | - Andy Ward
- Central Laser Facility, Science and Technology Facilities Council, Research Complex at Harwell, Didcot, Oxon, UK
| | - Tijs Ketelaar
- Laboratory of Cell Biology, Wageningen University, Droevendaalsesteeg, Wageningen, The Netherlands
| | - Norbert de Ruijter
- Laboratory of Cell Biology, Wageningen University, Droevendaalsesteeg, Wageningen, The Netherlands
| | - Chris Hawes
- Department of Biological and Medical Sciences, Faculty of Health and Life Sciences, Oxford Brookes University, Gipsy Lane, Headington, Oxford, UK
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Keicher J, Jaspert N, Weckermann K, Möller C, Throm C, Kintzi A, Oecking C. Arabidopsis 14-3-3 epsilon members contribute to polarity of PIN auxin carrier and auxin transport-related development. eLife 2017. [PMID: 28422008 DOI: 10.7554/elife.24336.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2023] Open
Abstract
Eukaryotic 14-3-3 proteins have been implicated in the regulation of diverse biological processes by phosphorylation-dependent protein-protein interactions. The Arabidopsis genome encodes two groups of 14-3-3s, one of which - epsilon - is thought to fulfill conserved cellular functions. Here, we assessed the in vivo role of the ancestral 14-3-3 epsilon group members. Their simultaneous and conditional repression by RNA interference and artificial microRNA in seedlings led to altered distribution patterns of the phytohormone auxin and associated auxin transport-related phenotypes, such as agravitropic growth. Moreover, 14-3-3 epsilon members were required for pronounced polar distribution of PIN-FORMED auxin efflux carriers within the plasma membrane. Defects in defined post-Golgi trafficking processes proved causal for this phenotype and might be due to lack of direct 14-3-3 interactions with factors crucial for membrane trafficking. Taken together, our data demonstrate a fundamental role for the ancient 14-3-3 epsilon group members in regulating PIN polarity and plant development.
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Affiliation(s)
- Jutta Keicher
- Plant Physiology, Center for Plant Molecular Biology, University of Tübingen, Tübingen, Germany
| | - Nina Jaspert
- Plant Physiology, Center for Plant Molecular Biology, University of Tübingen, Tübingen, Germany
| | - Katrin Weckermann
- Plant Physiology, Center for Plant Molecular Biology, University of Tübingen, Tübingen, Germany
| | - Claudia Möller
- Plant Physiology, Center for Plant Molecular Biology, University of Tübingen, Tübingen, Germany
| | - Christian Throm
- Plant Physiology, Center for Plant Molecular Biology, University of Tübingen, Tübingen, Germany
| | - Aaron Kintzi
- Plant Physiology, Center for Plant Molecular Biology, University of Tübingen, Tübingen, Germany
| | - Claudia Oecking
- Plant Physiology, Center for Plant Molecular Biology, University of Tübingen, Tübingen, Germany
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6
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Keicher J, Jaspert N, Weckermann K, Möller C, Throm C, Kintzi A, Oecking C. Arabidopsis 14-3-3 epsilon members contribute to polarity of PIN auxin carrier and auxin transport-related development. eLife 2017; 6. [PMID: 28422008 PMCID: PMC5397284 DOI: 10.7554/elife.24336] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 04/06/2017] [Indexed: 12/30/2022] Open
Abstract
Eukaryotic 14-3-3 proteins have been implicated in the regulation of diverse biological processes by phosphorylation-dependent protein-protein interactions. The Arabidopsis genome encodes two groups of 14-3-3s, one of which - epsilon - is thought to fulfill conserved cellular functions. Here, we assessed the in vivo role of the ancestral 14-3-3 epsilon group members. Their simultaneous and conditional repression by RNA interference and artificial microRNA in seedlings led to altered distribution patterns of the phytohormone auxin and associated auxin transport-related phenotypes, such as agravitropic growth. Moreover, 14-3-3 epsilon members were required for pronounced polar distribution of PIN-FORMED auxin efflux carriers within the plasma membrane. Defects in defined post-Golgi trafficking processes proved causal for this phenotype and might be due to lack of direct 14-3-3 interactions with factors crucial for membrane trafficking. Taken together, our data demonstrate a fundamental role for the ancient 14-3-3 epsilon group members in regulating PIN polarity and plant development.
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Affiliation(s)
- Jutta Keicher
- Plant Physiology, Center for Plant Molecular Biology, University of Tübingen, Tübingen, Germany
| | - Nina Jaspert
- Plant Physiology, Center for Plant Molecular Biology, University of Tübingen, Tübingen, Germany
| | - Katrin Weckermann
- Plant Physiology, Center for Plant Molecular Biology, University of Tübingen, Tübingen, Germany
| | - Claudia Möller
- Plant Physiology, Center for Plant Molecular Biology, University of Tübingen, Tübingen, Germany
| | - Christian Throm
- Plant Physiology, Center for Plant Molecular Biology, University of Tübingen, Tübingen, Germany
| | - Aaron Kintzi
- Plant Physiology, Center for Plant Molecular Biology, University of Tübingen, Tübingen, Germany
| | - Claudia Oecking
- Plant Physiology, Center for Plant Molecular Biology, University of Tübingen, Tübingen, Germany
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7
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Keicher J, Jaspert N, Weckermann K, Möller C, Throm C, Kintzi A, Oecking C. Arabidopsis 14-3-3 epsilon members contribute to polarity of PIN auxin carrier and auxin transport-related development. eLife 2017; 6. [PMID: 28422008 DOI: 10.7554/elife.24336.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 04/06/2017] [Indexed: 05/19/2023] Open
Abstract
Eukaryotic 14-3-3 proteins have been implicated in the regulation of diverse biological processes by phosphorylation-dependent protein-protein interactions. The Arabidopsis genome encodes two groups of 14-3-3s, one of which - epsilon - is thought to fulfill conserved cellular functions. Here, we assessed the in vivo role of the ancestral 14-3-3 epsilon group members. Their simultaneous and conditional repression by RNA interference and artificial microRNA in seedlings led to altered distribution patterns of the phytohormone auxin and associated auxin transport-related phenotypes, such as agravitropic growth. Moreover, 14-3-3 epsilon members were required for pronounced polar distribution of PIN-FORMED auxin efflux carriers within the plasma membrane. Defects in defined post-Golgi trafficking processes proved causal for this phenotype and might be due to lack of direct 14-3-3 interactions with factors crucial for membrane trafficking. Taken together, our data demonstrate a fundamental role for the ancient 14-3-3 epsilon group members in regulating PIN polarity and plant development.
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Affiliation(s)
- Jutta Keicher
- Plant Physiology, Center for Plant Molecular Biology, University of Tübingen, Tübingen, Germany
| | - Nina Jaspert
- Plant Physiology, Center for Plant Molecular Biology, University of Tübingen, Tübingen, Germany
| | - Katrin Weckermann
- Plant Physiology, Center for Plant Molecular Biology, University of Tübingen, Tübingen, Germany
| | - Claudia Möller
- Plant Physiology, Center for Plant Molecular Biology, University of Tübingen, Tübingen, Germany
| | - Christian Throm
- Plant Physiology, Center for Plant Molecular Biology, University of Tübingen, Tübingen, Germany
| | - Aaron Kintzi
- Plant Physiology, Center for Plant Molecular Biology, University of Tübingen, Tübingen, Germany
| | - Claudia Oecking
- Plant Physiology, Center for Plant Molecular Biology, University of Tübingen, Tübingen, Germany
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8
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Konopka-Postupolska D, Clark G. Annexins as Overlooked Regulators of Membrane Trafficking in Plant Cells. Int J Mol Sci 2017; 18:E863. [PMID: 28422051 PMCID: PMC5412444 DOI: 10.3390/ijms18040863] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2016] [Revised: 04/03/2017] [Accepted: 04/06/2017] [Indexed: 12/11/2022] Open
Abstract
Annexins are an evolutionary conserved superfamily of proteins able to bind membrane phospholipids in a calcium-dependent manner. Their physiological roles are still being intensively examined and it seems that, despite their general structural similarity, individual proteins are specialized toward specific functions. However, due to their general ability to coordinate membranes in a calcium-sensitive fashion they are thought to participate in membrane flow. In this review, we present a summary of the current understanding of cellular transport in plant cells and consider the possible roles of annexins in different stages of vesicular transport.
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Affiliation(s)
- Dorota Konopka-Postupolska
- Plant Biochemistry Department, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw 02-106, Poland.
| | - Greg Clark
- Molecular, Cell, and Developmental Biology, University of Texas, Austin, TX 78712, USA.
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Hirano T, Munnik T, Sato MH. Inhibition of phosphatidylinositol 3,5-bisphosphate production has pleiotropic effects on various membrane trafficking routes in Arabidopsis. PLANT & CELL PHYSIOLOGY 2017; 58:120-129. [PMID: 27803131 DOI: 10.1093/pcp/pcw164] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 09/15/2016] [Indexed: 06/06/2023]
Abstract
Phosphoinositides play an important role in various membrane trafficking events in eukaryotes. One of them, however, phosphatidylinositol 3,5-bisphosphate [PI(3,5)P2], has not been studied widely in plants. Using a combination of fluorescent reporter proteins and the PI(3,5)P2-specific inhibitor YM202636, here we demonstrated that in Arabidopsis thaliana, PI(3,5)P2 affects various membrane trafficking events, mostly in the post-Golgi routes. We found that YM201636 treatment effectively reduced PI(3,5)P2 concentration not only in the wild type but also in FAB1A-overexpressing Arabidopsis plants. In particular, reduced PI(3,5)P2 levels caused abnormal membrane dynamics of plasma membrane proteins, AUX1 and BOR1, with different trafficking patterns. Secretion and morphological characteristics of late endosomes and vacuoles were also affected by the decreased PI(3,5)P2 production. These pleiotropic defects in the post-Golgi trafficking events were caused by the inhibition of PI(3,5)P2 production. This effect is probably mediated by the inhibition of maturation of FAB1-positive late endosomes, thereby impairing late endosome function. In conclusion, our results imply that in Arabidopsis, late endosomes are involved in multiple post-Golgi membrane trafficking routes including not only vacuolar trafficking and endocytosis but also secretion.
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Affiliation(s)
- Tomoko Hirano
- Laboratory of Cellular Dynamics, Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Kyoto, Japan
| | - Teun Munnik
- Plant Physiology, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - Masa H Sato
- Laboratory of Cellular Dynamics, Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Kyoto, Japan
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10
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van de Meene AML, Doblin MS, Bacic A. The plant secretory pathway seen through the lens of the cell wall. PROTOPLASMA 2017; 254:75-94. [PMID: 26993347 DOI: 10.1007/s00709-016-0952-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 01/27/2016] [Accepted: 02/01/2016] [Indexed: 05/18/2023]
Abstract
Secretion in plant cells is often studied by looking at well-characterised, evolutionarily conserved membrane proteins associated with particular endomembrane compartments. Studies using live cell microscopy and fluorescent proteins have illuminated the highly dynamic nature of trafficking, and electron microscopy studies have resolved the ultrastructure of many compartments. Biochemical and molecular analyses have further informed about the function of particular proteins and endomembrane compartments. In plants, there are over 40 cell types, each with highly specialised functions, and hence potential variations in cell biological processes and cell wall structure. As the primary function of secretion in plant cells is for the biosynthesis of cell wall polysaccharides and apoplastic transport complexes, it follows that utilising our knowledge of cell wall glycosyltransferases (GTs) and their polysaccharide products will inform us about secretion. Indeed, this knowledge has led to novel insights into the secretory pathway, including previously unseen post-TGN secretory compartments. Conversely, our knowledge of trafficking routes of secretion will inform us about polarised and localised deposition of cell walls and their constituent polysaccharides/glycoproteins. In this review, we look at what is known about cell wall biosynthesis and the secretory pathway and how the different approaches can be used in a complementary manner to study secretion and provide novel insights into these processes.
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Affiliation(s)
- A M L van de Meene
- ARC Centre of Excellence in Plant Cell Walls, School of BioSciences, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - M S Doblin
- ARC Centre of Excellence in Plant Cell Walls, School of BioSciences, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Antony Bacic
- ARC Centre of Excellence in Plant Cell Walls, School of BioSciences, The University of Melbourne, Parkville, Victoria, 3010, Australia.
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Park HJ, Lee A, Lee SS, An DJ, Moon KB, Ahn JC, Kim HS, Cho HS. Overexpression of Golgi Protein CYP21-4s Improves Crop Productivity in Potato and Rice by Increasing the Abundance of Mannosidic Glycoproteins. FRONTIERS IN PLANT SCIENCE 2017; 8:1250. [PMID: 28775727 PMCID: PMC5517489 DOI: 10.3389/fpls.2017.01250] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 07/03/2017] [Indexed: 05/20/2023]
Abstract
CYP21-4 is a novel Golgi-localized cyclophilin protein involved in oxidative stress tolerance. Here, we generated transgenic plants overexpressing AtCYP21-4 and OsCYP21-4 in potato and rice, respectively. The stems and roots of AtCYP21-4-overexpressing potato plants were longer than those of wild-type (WT) plants, which resulted in heavier tubers. In vitro tuberization in the transgenic potato also resulted in significantly greater tuber number and weight, as well as a shorter time to microtuber formation. Similarly, OsCYP21-4-overexpressing transgenic rice plants had higher biomass and productivity with longer early-stage internodes than the WT and higher seed weight. Immunoblot analysis with CYP21-4 antibody showed that these productivity-enhancing phenotypes were associated with high CYP21-4s protein expression. Anatomically, transgenic potato stems exhibited higher lignin content in xylem cells and thicker leaves. In addition, relative content of mannosidic glycoproteins per unit of total protein was above 20% in transgenic potato tubers and rice grains. Based on these findings, we propose that CYP21-4s are involved in the growth and development of plant vegetative and storage tissues via their effects on glycoprotein abundance or glycan processing in the Golgi apparatus. Thus, increasing CYP21-4s expression in crops could represent an alternative way to increase crop productivity and yield.
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Affiliation(s)
- Hyun Ji Park
- Plant Systems Engineering Research Center, Korea Research Institute of Bioscience & BiotechnologyDaejeon, South Korea
| | - Areum Lee
- Plant Systems Engineering Research Center, Korea Research Institute of Bioscience & BiotechnologyDaejeon, South Korea
- Department of Biosystems and Bioengineering, KRIBB School of Biotechnology, Korea University of Science and TechnologyDaejeon, South Korea
| | - Sang Sook Lee
- Plant Systems Engineering Research Center, Korea Research Institute of Bioscience & BiotechnologyDaejeon, South Korea
| | - Dong-Ju An
- Plant Systems Engineering Research Center, Korea Research Institute of Bioscience & BiotechnologyDaejeon, South Korea
| | - Ki-Beom Moon
- Plant Systems Engineering Research Center, Korea Research Institute of Bioscience & BiotechnologyDaejeon, South Korea
| | - Jun Cheul Ahn
- Department of Pharmacology, College of Medicine, Seonam UniversityNamwon, South Korea
| | - Hyun-Soon Kim
- Plant Systems Engineering Research Center, Korea Research Institute of Bioscience & BiotechnologyDaejeon, South Korea
- *Correspondence: Hyun-Soon Kim
| | - Hye Sun Cho
- Plant Systems Engineering Research Center, Korea Research Institute of Bioscience & BiotechnologyDaejeon, South Korea
- Department of Biosystems and Bioengineering, KRIBB School of Biotechnology, Korea University of Science and TechnologyDaejeon, South Korea
- Hye Sun Cho
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Abstract
Unconventional protein secretion (UPS) describes secretion pathways that bypass one or several of the canonical secretion pit-stops on the way to the plasma membrane, and/or involve the secretion of leaderless proteins. So far, alternatives to conventional secretion were primarily observed and studied in yeast and animal cells. The sessile lifestyle of plants brings with it unique restraints on how they adapt to adverse conditions and environmental challenges. Recently, attention towards unconventional secretion pathways in plant cells has substantially increased, with the large number of leaderless proteins identified through proteomic studies. While UPS pathways in plants are certainly not yet exhaustively researched, an emerging notion is that induction of UPS pathways is correlated with pathogenesis and stress responses. Given the multitude UPS events observed, comprehensively organizing the routes proteins take to the apoplast in defined UPS categories is challenging. With the establishment of a larger collection of studied plant proteins taking these UPS pathways, a clearer picture of endomembrane trafficking as a whole will emerge. There are several novel enabling technologies, such as vesicle proteomics and chemical genomics, with great potential for dissecting secretion pathways, providing information about the cargo that travels along them and the conditions that induce them.
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Affiliation(s)
- Destiny J Davis
- Department of Plant Sciences, University of California, Asmundson Hall, One Shields Avenue, Davis, CA, 95616, USA
| | - Byung-Ho Kang
- Center for Organelle Biogenesis and Function, School of Life Sciences, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Angelo S Heringer
- Department of Plant Sciences, University of California, Asmundson Hall, One Shields Avenue, Davis, CA, 95616, USA
| | - Thomas E Wilkop
- Department of Plant Sciences, University of California, Asmundson Hall, One Shields Avenue, Davis, CA, 95616, USA.
| | - Georgia Drakakaki
- Department of Plant Sciences, University of California, Asmundson Hall, One Shields Avenue, Davis, CA, 95616, USA.
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Robinson DG, Ding Y, Jiang L. Unconventional protein secretion in plants: a critical assessment. PROTOPLASMA 2016; 253:31-43. [PMID: 26410830 DOI: 10.1007/s00709-015-0887-1] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 09/18/2015] [Indexed: 05/27/2023]
Abstract
Unconventional protein secretion (UPS) is a collective term for mechanisms by which cytosolic proteins that lack a signal peptide ("leaderless secretory proteins" (LSPs)) can gain access to the cell exterior. Numerous examples of UPS have been well documented in animal and yeast cells. In contrast, our understanding of the mechanism(s) and function of UPS in plants is very limited. This review evaluates the available literature on this subject. The apparent large numbers of LSPs in the plant secretome suggest that UPS also occurs in plants but is not a proof. Although the direct transport of LSPs across the plant plasma membrane (PM) has not yet been described, it is possible that as in other eukaryotes, exosomes may be released from plant cells through fusion of multivesicular bodies (MVBs) with the PM. In this way, LSPs, but also small RNAs (sRNAs), that are passively taken up from the cytosol into the intraluminal vesicles of MVBs, could reach the apoplast. Another possible mechanism is the recently discovered exocyst-positive organelle (EXPO), a double-membrane-bound compartment, distinct from autophagosomes, which appears to sequester LSPs.
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Affiliation(s)
- David G Robinson
- Centre for Organismal Studies, University of Heidelberg, Im Neuenheimer Feld 230, D-69120, Heidelberg, Germany.
| | - Yu Ding
- Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Liwen Jiang
- Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
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Lin Y, Ding Y, Wang J, Shen J, Kung CH, Zhuang X, Cui Y, Yin Z, Xia Y, Lin H, Robinson DG, Jiang L. Exocyst-Positive Organelles and Autophagosomes Are Distinct Organelles in Plants. PLANT PHYSIOLOGY 2015; 169:1917-32. [PMID: 26358417 PMCID: PMC4634068 DOI: 10.1104/pp.15.00953] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 09/09/2015] [Indexed: 05/23/2023]
Abstract
Autophagosomes are organelles that deliver cytosolic proteins for degradation in the vacuole of the cell. In contrast, exocyst-positive organelles (EXPO) deliver cytosolic proteins to the cell surface and therefore represent a form of unconventional protein secretion. Because both structures have two boundary membranes, it has been suggested that they may have been falsely treated as separate entities. Using suspension culture cells and root tissue cells of transgenic Arabidopsis (Arabidopsis thaliana) plants expressing either the EXPO marker Arabidopsis Exo70E2-GFP or the autophagosome marker yellow fluorescent protein (YFP)-autophagy-related gene 8e/f (ATG8e/f), and using specific antibodies against Exo70E2 and ATG8, we have now established that, in normally growing cells, EXPO and autophagosomes are distinct from one another. However, when cells/roots are subjected to autophagy induction, EXPO as well as autophagosomes fuse with the vacuole. In the presence of concanamycin A, the punctate fluorescent signals from both organelles inside the vacuole remain visible for hours and overlap to a significant degree. Tonoplast staining with FM4-64/YFP-Rab7-like GTPase/YFP-vesicle-associated membrane protein711 confirmed the internalization of tonoplast membrane concomitant with the sequestration of EXPO and autophagosomes. This suggests that EXPO and autophagosomes may be related to one another; however, whereas induction of autophagy led to an increase in the amount of ATG8 recruited to membranes, Exo70E2 did not respond in a similar manner.
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Affiliation(s)
- Youshun Lin
- Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.L., Y.D., J.W., J.S., C.H.K., X.Z., Y.C., L.J.);CUHK Shenzhen Research Institute, Chinese University of Hong Kong, Shenzhen 518057, China (L.J.);Department of Biology, Hong Kong Baptist University, Hong Kong, China (Z.Y., Y.X.);Partner State Key Laboratory of Agrobiotechnology, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.X.);National Key Laboratory of Plant Molecular Genetics and National Center for Plant Gene Research (Shanghai), Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China (H.L.); andCentre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany (D.G.R.)
| | - Yu Ding
- Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.L., Y.D., J.W., J.S., C.H.K., X.Z., Y.C., L.J.);CUHK Shenzhen Research Institute, Chinese University of Hong Kong, Shenzhen 518057, China (L.J.);Department of Biology, Hong Kong Baptist University, Hong Kong, China (Z.Y., Y.X.);Partner State Key Laboratory of Agrobiotechnology, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.X.);National Key Laboratory of Plant Molecular Genetics and National Center for Plant Gene Research (Shanghai), Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China (H.L.); andCentre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany (D.G.R.)
| | - Juan Wang
- Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.L., Y.D., J.W., J.S., C.H.K., X.Z., Y.C., L.J.);CUHK Shenzhen Research Institute, Chinese University of Hong Kong, Shenzhen 518057, China (L.J.);Department of Biology, Hong Kong Baptist University, Hong Kong, China (Z.Y., Y.X.);Partner State Key Laboratory of Agrobiotechnology, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.X.);National Key Laboratory of Plant Molecular Genetics and National Center for Plant Gene Research (Shanghai), Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China (H.L.); andCentre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany (D.G.R.)
| | - Jinbo Shen
- Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.L., Y.D., J.W., J.S., C.H.K., X.Z., Y.C., L.J.);CUHK Shenzhen Research Institute, Chinese University of Hong Kong, Shenzhen 518057, China (L.J.);Department of Biology, Hong Kong Baptist University, Hong Kong, China (Z.Y., Y.X.);Partner State Key Laboratory of Agrobiotechnology, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.X.);National Key Laboratory of Plant Molecular Genetics and National Center for Plant Gene Research (Shanghai), Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China (H.L.); andCentre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany (D.G.R.)
| | - Chun Hong Kung
- Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.L., Y.D., J.W., J.S., C.H.K., X.Z., Y.C., L.J.);CUHK Shenzhen Research Institute, Chinese University of Hong Kong, Shenzhen 518057, China (L.J.);Department of Biology, Hong Kong Baptist University, Hong Kong, China (Z.Y., Y.X.);Partner State Key Laboratory of Agrobiotechnology, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.X.);National Key Laboratory of Plant Molecular Genetics and National Center for Plant Gene Research (Shanghai), Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China (H.L.); andCentre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany (D.G.R.)
| | - Xiaohong Zhuang
- Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.L., Y.D., J.W., J.S., C.H.K., X.Z., Y.C., L.J.);CUHK Shenzhen Research Institute, Chinese University of Hong Kong, Shenzhen 518057, China (L.J.);Department of Biology, Hong Kong Baptist University, Hong Kong, China (Z.Y., Y.X.);Partner State Key Laboratory of Agrobiotechnology, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.X.);National Key Laboratory of Plant Molecular Genetics and National Center for Plant Gene Research (Shanghai), Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China (H.L.); andCentre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany (D.G.R.)
| | - Yong Cui
- Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.L., Y.D., J.W., J.S., C.H.K., X.Z., Y.C., L.J.);CUHK Shenzhen Research Institute, Chinese University of Hong Kong, Shenzhen 518057, China (L.J.);Department of Biology, Hong Kong Baptist University, Hong Kong, China (Z.Y., Y.X.);Partner State Key Laboratory of Agrobiotechnology, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.X.);National Key Laboratory of Plant Molecular Genetics and National Center for Plant Gene Research (Shanghai), Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China (H.L.); andCentre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany (D.G.R.)
| | - Zhao Yin
- Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.L., Y.D., J.W., J.S., C.H.K., X.Z., Y.C., L.J.);CUHK Shenzhen Research Institute, Chinese University of Hong Kong, Shenzhen 518057, China (L.J.);Department of Biology, Hong Kong Baptist University, Hong Kong, China (Z.Y., Y.X.);Partner State Key Laboratory of Agrobiotechnology, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.X.);National Key Laboratory of Plant Molecular Genetics and National Center for Plant Gene Research (Shanghai), Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China (H.L.); andCentre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany (D.G.R.)
| | - Yiji Xia
- Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.L., Y.D., J.W., J.S., C.H.K., X.Z., Y.C., L.J.);CUHK Shenzhen Research Institute, Chinese University of Hong Kong, Shenzhen 518057, China (L.J.);Department of Biology, Hong Kong Baptist University, Hong Kong, China (Z.Y., Y.X.);Partner State Key Laboratory of Agrobiotechnology, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.X.);National Key Laboratory of Plant Molecular Genetics and National Center for Plant Gene Research (Shanghai), Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China (H.L.); andCentre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany (D.G.R.)
| | - Hongxuan Lin
- Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.L., Y.D., J.W., J.S., C.H.K., X.Z., Y.C., L.J.);CUHK Shenzhen Research Institute, Chinese University of Hong Kong, Shenzhen 518057, China (L.J.);Department of Biology, Hong Kong Baptist University, Hong Kong, China (Z.Y., Y.X.);Partner State Key Laboratory of Agrobiotechnology, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.X.);National Key Laboratory of Plant Molecular Genetics and National Center for Plant Gene Research (Shanghai), Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China (H.L.); andCentre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany (D.G.R.)
| | - David G Robinson
- Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.L., Y.D., J.W., J.S., C.H.K., X.Z., Y.C., L.J.);CUHK Shenzhen Research Institute, Chinese University of Hong Kong, Shenzhen 518057, China (L.J.);Department of Biology, Hong Kong Baptist University, Hong Kong, China (Z.Y., Y.X.);Partner State Key Laboratory of Agrobiotechnology, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.X.);National Key Laboratory of Plant Molecular Genetics and National Center for Plant Gene Research (Shanghai), Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China (H.L.); andCentre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany (D.G.R.)
| | - Liwen Jiang
- Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.L., Y.D., J.W., J.S., C.H.K., X.Z., Y.C., L.J.);CUHK Shenzhen Research Institute, Chinese University of Hong Kong, Shenzhen 518057, China (L.J.);Department of Biology, Hong Kong Baptist University, Hong Kong, China (Z.Y., Y.X.);Partner State Key Laboratory of Agrobiotechnology, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (Y.X.);National Key Laboratory of Plant Molecular Genetics and National Center for Plant Gene Research (Shanghai), Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China (H.L.); andCentre for Organismal Studies, University of Heidelberg, D-69120 Heidelberg, Germany (D.G.R.)
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15
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Hirano T, Munnik T, Sato MH. Phosphatidylinositol 3-Phosphate 5-Kinase, FAB1/PIKfyve Kinase Mediates Endosome Maturation to Establish Endosome-Cortical Microtubule Interaction in Arabidopsis. PLANT PHYSIOLOGY 2015; 169:1961-74. [PMID: 26353760 PMCID: PMC4634102 DOI: 10.1104/pp.15.01368] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 09/09/2015] [Indexed: 05/19/2023]
Abstract
Phosphatidylinositol 3,5-bisphosphate [PtdIns(3,5)P2] is an important lipid in membrane trafficking in animal and yeast systems; however, its role is still largely obscure in plants. Here, we demonstrate that the phosphatidylinositol 3-phosphate 5-kinase, formation of aploid and binucleate cells1 (FAB1)/FYVE finger-containing phosphoinositide kinase (PIKfyve), and its product, PtdIns(3,5)P2, are essential for the maturation process of endosomes to mediate cortical microtubule association of endosomes, thereby controlling proper PIN-FORMED protein trafficking in young cortical and stele cells of root. We found that FAB1 predominantly localizes on the Sorting Nexin1 (SNX1)-residing late endosomes, and a loss of FAB1 function causes the release of late endosomal proteins, Ara7, and SNX1 from the endosome membrane, indicating that FAB1, or its product PtdIns(3,5)P2, mediates the maturation process of the late endosomes. We also found that loss of FAB1 function causes the release of endosomes from cortical microtubules and disturbs proper cortical microtubule organization.
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Affiliation(s)
- Tomoko Hirano
- Laboratory of Cellular Dynamics, Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Kyoto 606-8522, Japan (T.H., M.H.S.); andSection Plant Physiology, Swammerdam Institute for Life Sciences, University of Amsterdam, 1098 XH Amsterdam, The Netherlands (T.M.)
| | - Teun Munnik
- Laboratory of Cellular Dynamics, Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Kyoto 606-8522, Japan (T.H., M.H.S.); andSection Plant Physiology, Swammerdam Institute for Life Sciences, University of Amsterdam, 1098 XH Amsterdam, The Netherlands (T.M.)
| | - Masa H Sato
- Laboratory of Cellular Dynamics, Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Kyoto 606-8522, Japan (T.H., M.H.S.); andSection Plant Physiology, Swammerdam Institute for Life Sciences, University of Amsterdam, 1098 XH Amsterdam, The Netherlands (T.M.)
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16
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Heard W, Sklenář J, Tomé DFA, Robatzek S, Jones AME. Identification of Regulatory and Cargo Proteins of Endosomal and Secretory Pathways in Arabidopsis thaliana by Proteomic Dissection. Mol Cell Proteomics 2015; 14:1796-813. [PMID: 25900983 DOI: 10.1074/mcp.m115.050286] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Indexed: 12/19/2022] Open
Abstract
The cell's endomembranes comprise an intricate, highly dynamic and well-organized system. In plants, the proteins that regulate function of the various endomembrane compartments and their cargo remain largely unknown. Our aim was to dissect subcellular trafficking routes by enriching for partially overlapping subpopulations of endosomal proteomes associated with endomembrane markers. We selected RABD2a/ARA5, RABF2b/ARA7, RABF1/ARA6, and RABG3f as markers for combinations of the Golgi, trans-Golgi network (TGN), early endosomes (EE), secretory vesicles, late endosomes (LE), multivesicular bodies (MVB), and the tonoplast. As comparisons we used Golgi transport 1 (GOT1), which localizes to the Golgi, clathrin light chain 2 (CLC2) labeling clathrin-coated vesicles and pits and the vesicle-associated membrane protein 711 (VAMP711) present at the tonoplast. We developed an easy-to-use method by refining published protocols based on affinity purification of fluorescent fusion constructs to these seven subcellular marker proteins in Arabidopsis thaliana seedlings. We present a total of 433 proteins, only five of which were shared among all enrichments, while many proteins were common between endomembrane compartments of the same trafficking route. Approximately half, 251 proteins, were assigned to one enrichment only. Our dataset contains known regulators of endosome functions including small GTPases, SNAREs, and tethering complexes. We identify known cargo proteins such as PIN3, PEN3, CESA, and the recently defined TPLATE complex. The subcellular localization of two GTPase regulators predicted from our enrichments was validated using live-cell imaging. This is the first proteomic dataset to discriminate between such highly overlapping endomembrane compartments in plants and can be used as a general proteomic resource to predict the localization of proteins and identify the components of regulatory complexes and provides a useful tool for the identification of new protein markers of the endomembrane system.
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Affiliation(s)
- William Heard
- From the ‡The Sainsbury Laboratory, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Jan Sklenář
- From the ‡The Sainsbury Laboratory, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Daniel F A Tomé
- §The School of Life Sciences, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK
| | - Silke Robatzek
- From the ‡The Sainsbury Laboratory, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Alexandra M E Jones
- From the ‡The Sainsbury Laboratory, Norwich Research Park, Norwich, NR4 7UH, UK; §The School of Life Sciences, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK
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17
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von Wangenheim D, Rosero A, Komis G, Šamajová O, Ovečka M, Voigt B, Šamaj J. Endosomal Interactions during Root Hair Growth. FRONTIERS IN PLANT SCIENCE 2015; 6:1262. [PMID: 26858728 PMCID: PMC4731515 DOI: 10.3389/fpls.2015.01262] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 12/24/2015] [Indexed: 05/21/2023]
Abstract
The dynamic localization of endosomal compartments labeled with targeted fluorescent protein tags is routinely followed by time lapse fluorescence microscopy approaches and single particle tracking algorithms. In this way trajectories of individual endosomes can be mapped and linked to physiological processes as cell growth. However, other aspects of dynamic behavior including endosomal interactions are difficult to follow in this manner. Therefore, we characterized the localization and dynamic properties of early and late endosomes throughout the entire course of root hair formation by means of spinning disc time lapse imaging and post-acquisition automated multitracking and quantitative analysis. Our results show differential motile behavior of early and late endosomes and interactions of late endosomes that may be specified to particular root hair domains. Detailed data analysis revealed a particular transient interaction between late endosomes-termed herein as dancing-endosomes-which is not concluding to vesicular fusion. Endosomes preferentially located in the root hair tip interacted as dancing-endosomes and traveled short distances during this interaction. Finally, sizes of early and late endosomes were addressed by means of super-resolution structured illumination microscopy (SIM) to corroborate measurements on the spinning disc. This is a first study providing quantitative microscopic data on dynamic spatio-temporal interactions of endosomes during root hair tip growth.
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Affiliation(s)
- Daniel von Wangenheim
- Department of Plant Cell Biology, Institute of Cellular and Molecular Botany, University of BonnBonn, Germany
| | - Amparo Rosero
- Department of Cell Biology, Faculty of Science, Centre of the Region Haná for Biotechnological and Agricultural Research, Palacký UniversityOlomouc, Czech Republic
| | - George Komis
- Department of Cell Biology, Faculty of Science, Centre of the Region Haná for Biotechnological and Agricultural Research, Palacký UniversityOlomouc, Czech Republic
| | - Olga Šamajová
- Department of Cell Biology, Faculty of Science, Centre of the Region Haná for Biotechnological and Agricultural Research, Palacký UniversityOlomouc, Czech Republic
| | - Miroslav Ovečka
- Department of Cell Biology, Faculty of Science, Centre of the Region Haná for Biotechnological and Agricultural Research, Palacký UniversityOlomouc, Czech Republic
| | - Boris Voigt
- Department of Plant Cell Biology, Institute of Cellular and Molecular Botany, University of BonnBonn, Germany
| | - Jozef Šamaj
- Department of Cell Biology, Faculty of Science, Centre of the Region Haná for Biotechnological and Agricultural Research, Palacký UniversityOlomouc, Czech Republic
- *Correspondence: Jozef Šamaj
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Roy R, Bassham DC. Gravitropism and Lateral Root Emergence are Dependent on the Trans-Golgi Network Protein TNO1. FRONTIERS IN PLANT SCIENCE 2015; 6:969. [PMID: 26617617 PMCID: PMC4642138 DOI: 10.3389/fpls.2015.00969] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 10/22/2015] [Indexed: 05/07/2023]
Abstract
The trans-Golgi network (TGN) is a dynamic organelle that functions as a relay station for receiving endocytosed cargo, directing secretory cargo, and trafficking to the vacuole. TGN-localized SYP41-interacting protein (TNO1) is a large, TGN-localized, coiled-coil protein that associates with the membrane fusion protein SYP41, a target SNARE, and is required for efficient protein trafficking to the vacuole. Here, we show that a tno1 mutant has auxin transport-related defects. Mutant roots have delayed lateral root emergence, decreased gravitropic bending of plant organs and increased sensitivity to the auxin analog 2,4-dichlorophenoxyacetic acid and the natural auxin 3-indoleacetic acid. Auxin asymmetry at the tips of elongating stage II lateral roots was reduced in the tno1 mutant, suggesting a role for TNO1 in cellular auxin transport during lateral root emergence. During gravistimulation, tno1 roots exhibited delayed auxin transport from the columella to the basal epidermal cells. Endocytosis to the TGN was unaffected in the mutant, indicating that bulk endocytic defects are not responsible for the observed phenotypes. Together these studies demonstrate a role for TNO1 in mediating auxin responses during root development and gravistimulation, potentially through trafficking of auxin transport proteins.
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Affiliation(s)
- Rahul Roy
- Department of Genetics, Development and Cell Biology, Iowa State University, AmesIA, USA
- Interdepartmental Genetics Program, Iowa State University, AmesIA, USA
| | - Diane C. Bassham
- Department of Genetics, Development and Cell Biology, Iowa State University, AmesIA, USA
- Interdepartmental Genetics Program, Iowa State University, AmesIA, USA
- Plant Sciences Institute, Iowa State University, AmesIA, USA
- *Correspondence: Diane C. Bassham,
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19
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Zouhar J, Sauer M. Helping hands for budding prospects: ENTH/ANTH/VHS accessory proteins in endocytosis, vacuolar transport, and secretion. THE PLANT CELL 2014; 26:4232-44. [PMID: 25415979 PMCID: PMC4277227 DOI: 10.1105/tpc.114.131680] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Revised: 10/31/2014] [Accepted: 11/13/2014] [Indexed: 05/18/2023]
Abstract
Coated vesicles provide a major mechanism for the transport of proteins through the endomembrane system of plants. Transport between the endoplasmic reticulum and the Golgi involves vesicles with COPI and COPII coats, whereas clathrin is the predominant coat in endocytosis and post-Golgi trafficking. Sorting of cargo, coat assembly, budding, and fission are all complex and tightly regulated processes that involve many proteins. The mechanisms and responsible factors are largely conserved in eukaryotes, and increasing organismal complexity tends to be associated with a greater numbers of individual family members. Among the key factors is the class of ENTH/ANTH/VHS domain-containing proteins, which link membrane subdomains, clathrin, and other adapter proteins involved in early steps of clathrin coated vesicle formation. More than 30 Arabidopsis thaliana proteins contain this domain, but their generally low sequence conservation has made functional classification difficult. Reports from the last two years have greatly expanded our knowledge of these proteins and suggest that ENTH/ANTH/VHS domain proteins are involved in various instances of clathrin-related endomembrane trafficking in plants. This review aims to summarize these new findings and discuss the broader context of clathrin-dependent plant vesicular transport.
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Affiliation(s)
- Jan Zouhar
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, 28223 Madrid, Spain
| | - Michael Sauer
- Institute for Bichemistry and Biology, University of Potsdam, 10627 Potsdam, Germany
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20
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Zheng J, Han SW, Rodriguez-Welsh MF, Rojas-Pierce M. Homotypic vacuole fusion requires VTI11 and is regulated by phosphoinositides. MOLECULAR PLANT 2014; 7:1026-1040. [PMID: 24569132 DOI: 10.1093/mp/ssu019] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Most plant cells contain a large central vacuole that is essential to maintain cellular turgor. We report a new mutant allele of VTI11 that implicates the SNARE protein VTI11 in homotypic fusion of protein storage and lytic vacuoles. Fusion of the multiple vacuoles present in vti11 mutants could be induced by treatment with Wortmannin and LY294002, which are inhibitors of Phosphatidylinositol 3-Kinase (PI3K). We provide evidence that Phosphatidylinositol 3-Phosphate (PtdIns(3)P) regulates vacuole fusion in vti11 mutants, and that fusion of these vacuoles requires intact microtubules and actin filaments. Finally, we show that Wortmannin also induced the fusion of guard cell vacuoles in fava beans, where vacuoles are naturally fragmented after ABA-induced stomata closure. These results suggest a ubiquitous role of phosphoinositides in vacuole fusion, both during the development of the large central vacuole and during the dynamic vacuole remodeling that occurs as part of stomata movements.
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Affiliation(s)
- Jiameng Zheng
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA
| | - Sang Won Han
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA
| | | | - Marcela Rojas-Pierce
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA.
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Delivering of proteins to the plant vacuole--an update. Int J Mol Sci 2014; 15:7611-23. [PMID: 24802873 PMCID: PMC4057694 DOI: 10.3390/ijms15057611] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 04/21/2014] [Accepted: 04/22/2014] [Indexed: 01/17/2023] Open
Abstract
Trafficking of soluble cargo to the vacuole is far from being a closed issue as it can occur by different routes and involve different intermediates. The textbook view of proteins being sorted at the post-Golgi level to the lytic vacuole via the pre-vacuole or to the protein storage vacuole mediated by dense vesicles is now challenged as novel routes are being disclosed and vacuoles with intermediate characteristics described. The identification of Vacuolar Sorting Determinants is a key signature to understand protein trafficking to the vacuole. Despite the long established vacuolar signals, some others have been described in the last few years, with different properties that can be specific for some cells or some types of vacuoles. There are also reports of proteins having two different vacuolar signals and their significance is questionable: a way to increase the efficiency of the sorting or different sorting depending on the protein roles in a specific context? Along came the idea of differential vacuolar sorting, suggesting a possible specialization of the trafficking pathways according to the type of cell and specific needs. In this review, we show the recent advances in the field and focus on different aspects of protein trafficking to the vacuoles.
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22
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Uehara M, Wang S, Kamiya T, Shigenobu S, Yamaguchi K, Fujiwara T, Naito S, Takano J. Identification and Characterization of an Arabidopsis Mutant with Altered Localization of NIP5;1, a Plasma Membrane Boric Acid Channel, Reveals the Requirement for d-Galactose in Endomembrane Organization. ACTA ACUST UNITED AC 2014; 55:704-14. [DOI: 10.1093/pcp/pct191] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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23
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Groen AJ, Sancho-Andrés G, Breckels LM, Gatto L, Aniento F, Lilley KS. Identification of trans-golgi network proteins in Arabidopsis thaliana root tissue. J Proteome Res 2014; 13:763-76. [PMID: 24344820 PMCID: PMC3929368 DOI: 10.1021/pr4008464] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
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Knowledge of protein
subcellular localization assists in the elucidation
of protein function and understanding of different biological mechanisms
that occur at discrete subcellular niches. Organelle-centric proteomics
enables localization of thousands of proteins simultaneously. Although
such techniques have successfully allowed organelle protein catalogues
to be achieved, they rely on the purification or significant enrichment
of the organelle of interest, which is not achievable for many organelles.
Incomplete separation of organelles leads to false discoveries, with
erroneous assignments. Proteomics methods that measure the distribution
patterns of specific organelle markers along density gradients are
able to assign proteins of unknown localization based on comigration
with known organelle markers, without the need for organelle purification.
These methods are greatly enhanced when coupled to sophisticated computational
tools. Here we apply and compare multiple approaches to establish
a high-confidence data set of Arabidopsis root tissue
trans-Golgi network (TGN) proteins. The method employed involves immunoisolations
of the TGN, coupled to probability-based organelle proteomics techniques.
Specifically, the technique known as LOPIT (localization of organelle
protein by isotope tagging), couples density centrifugation with quantitative
mass-spectometry-based proteomics using isobaric labeling and targeted
methods with semisupervised machine learning methods. We demonstrate
that while the immunoisolation method gives rise to a significant
data set, the approach is unable to distinguish cargo proteins and
persistent contaminants from full-time residents of the TGN. The LOPIT
approach, however, returns information about many subcellular niches
simultaneously and the steady-state location of proteins. Importantly,
therefore, it is able to dissect proteins present in more than one
organelle and cargo proteins en route to other cellular destinations
from proteins whose steady-state location favors the TGN. Using this
approach, we present a robust list of Arabidopsis TGN proteins.
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Affiliation(s)
- Arnoud J Groen
- Cambridge Centre for Proteomics, Cambridge Systems Biology Centre, Department of Biochemistry, University of Cambridge , 80 Tennis Court Road, Cambridge CB2 1GA, United Kingdom
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24
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Zheng J, Han SW, Munnik T, Rojas-Pierce M. Multiple vacuoles in impaired tonoplast trafficking3 mutants are independent organelles. PLANT SIGNALING & BEHAVIOR 2014; 9:e972113. [PMID: 25482812 PMCID: PMC4623060 DOI: 10.4161/psb.29783] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Plant vacuoles are essential and dynamic organelles, and mechanisms of vacuole biogenesis and fusion are not well characterized. We recently demonstrated that Wortmannin, an inhibitor of Phosphatidylinositol 3-Kinase (PI3K), induces the fusion of plant vacuoles both in roots of itt3/vti11 mutant alleles and in guard cells of wild type Arabidopsis and Fava bean. Here we used Fluorescence Recovery After Photobleaching (FRAP) to demonstrate that the vacuoles in itt3/vti11 are independent organelles. Furthermore, we used fluorescent protein reporters that bind specifically to Phosphatidylinositol 3-Phosphate (PtdIns(3)P) or PtdIns(4)P to show that Wortmannin treatments that induce the fusion of vti11 vacuoles result in the loss of PtdIns(3)P from cellular membranes. These results provided supporting evidence for a critical role of PtdIns(3)P in vacuole fusion in roots and guard cells.
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Affiliation(s)
- Jiameng Zheng
- Department of Plant and Microbial Biology; North Carolina State University; Raleigh, NC USA
| | - Sang Won Han
- Department of Plant and Microbial Biology; North Carolina State University; Raleigh, NC USA
| | - Teun Munnik
- Department of Plant Physiology; Swammerdam Institute for Life Sciences; University of Amsterdam; Amsterdam, Netherlands
| | - Marcela Rojas-Pierce
- Department of Plant and Microbial Biology; North Carolina State University; Raleigh, NC USA
- Correspondence to: Marcela Rojas-Pierce;
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25
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Hoepflinger MC, Geretschlaeger A, Sommer A, Hoeftberger M, Nishiyama T, Sakayama H, Hammerl P, Tenhaken R, Ueda T, Foissner I. Molecular and biochemical analysis of the first ARA6 homologue, a RAB5 GTPase, from green algae. JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:5553-68. [PMID: 24127512 PMCID: PMC3871812 DOI: 10.1093/jxb/ert322] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
RAB5 GTPases are important regulators of endosomal membrane traffic in yeast, plants, and animals. A specific subgroup of this family, the ARA6 group, has been described in land plants including bryophytes, lycophytes, and flowering plants. Here, we report on the isolation of an ARA6 homologue in a green alga. CaARA6 (CaRABF1) from Chara australis, a member of the Characeae that is a close relative of land plants, encodes a polypeptide of 237 aa with a calculated molecular mass of 25.4 kDa, which is highly similar to ARA6 members from Arabidopsis thaliana and other land plants and has GTPase activity. When expressed in Nicotiana benthamiana leaf epidermal cells, fluorescently tagged CaARA6 labelled organelles with diameters between 0.2 and 1.2 µm, which co-localized with fluorescently tagged AtARA6 known to be present on multivesicular endosomes. Mutations in the membrane-anchoring and GTP-binding sites altered the localization of CaARA6 comparable to that of A. thaliana ARA6 (RABF1). In characean internodal cells, confocal immunofluorescence and immunogold electron microscopy with antibodies against AtARA6 and CaARA6 revealed ARA6 epitopes not only at multivesicular endosomes but also at the plasma membrane, including convoluted domains (charasomes), and at the trans-Golgi network. Our findings demonstrate that ARA6-like proteins have a more ancient origin than previously thought. They indicate further that ARA6-like proteins could have different functions in spite of the high similarity between characean algae and flowering plants.
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Affiliation(s)
- Marion C. Hoepflinger
- Plant Physiology/Cell Biology, University of Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg, Austria
| | - Anja Geretschlaeger
- Plant Physiology/Cell Biology, University of Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg, Austria
| | - Aniela Sommer
- Plant Physiology/Cell Biology, University of Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg, Austria
| | - Margit Hoeftberger
- Plant Physiology/Cell Biology, University of Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg, Austria
| | - Tomoaki Nishiyama
- Advanced Science Research Center, Kanazawa University, 13-1 Takara-machi, Kanazawa, Ishikawa 920-0934, Japan
| | - Hidetoshi Sakayama
- Department of Biology, Graduate School of Science, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe, Hyogo 657-8501, Japan
| | - Peter Hammerl
- Central Animal Facility, University of Salzburg, Hellbrunnerstr. 34, 5020 Salzburg, Austria
| | - Raimund Tenhaken
- Plant Physiology/Cell Biology, University of Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg, Austria
| | - Takashi Ueda
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Ilse Foissner
- Plant Physiology/Cell Biology, University of Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg, Austria
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26
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Rojas-Pierce M. Targeting of tonoplast proteins to the vacuole. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2013; 211:132-136. [PMID: 23987818 DOI: 10.1016/j.plantsci.2013.07.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2013] [Revised: 07/08/2013] [Accepted: 07/10/2013] [Indexed: 06/02/2023]
Abstract
Vacuoles are essential for plant growth and development, and are dynamic compartments that require constant deposition of integral membrane proteins. These membrane proteins carry out many critical functions of the vacuole such as transporting ions and metabolites for vacuolar storage. Understanding the mechanisms for targeting proteins to the vacuolar membrane, or tonoplast, is important for developing novel applications for biotechnology. The mechanisms to target tonoplast proteins to the vacuole are quite complex. Multiple routes, including both Golgi-dependent and Golgi-independent mechanisms, have been implicated in tonoplast protein trafficking. A few endomembrane proteins that regulate this traffic at the level of the endoplasmic reticulum, the pre-vacuolar compartment and the tonoplast are now known. Recent reports indicate that the Golgi-dependent and independent pathways may merge at the level of the pre-vacuolar compartment. Finally, the small GTP-binding protein Rab7 and the SNARE protein SYP21 have been implicated in the traffic of tonoplast proteins from the pre-vacuolar compartment to the tonoplast. With multiple cargo proteins being analyzed under a variety of experimental systems, a clearer picture for targeting mechanisms for tonoplast proteins is starting to emerge.
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Affiliation(s)
- Marcela Rojas-Pierce
- Department of Plant Biology, North Carolina State University, Raleigh, NC 27695, United States.
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27
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Arabidopsis μ-adaptin subunit AP1M of adaptor protein complex 1 mediates late secretory and vacuolar traffic and is required for growth. Proc Natl Acad Sci U S A 2013; 110:10318-23. [PMID: 23733933 DOI: 10.1073/pnas.1300460110] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Adaptor protein (AP) complexes are the predominant coat proteins of membrane vesicles in post-Golgi trafficking of mammalian cells. Each AP complex contains a specific medium subunit, μ-adaptin, that selects cargo proteins bearing sequence-specific sorting motifs. Much less is known about the AP complexes and their μ subunits in plants. Because of uncertain homology, the μ-adaptins of Arabidopsis have been designated muA through muD [Happel et al. (2004) Plant J 37(5):678-693]. Furthermore, only muD has been assigned to a specific AP complex, AP-3, involved in Golgi-vacuolar trafficking [Niihama et al. (2009) Plant Cell Physiol 50(12):2057-2068, Zwiewka et al. (2011) Cell Res 21(12):1711-1722, and Wolfenstetter et al. (2012) Plant Cell 24(1):215-232]. In contrast, the μ subunit of neither the post-Golgi trafficking AP-1 complex nor the endocytic AP-2 complex has been identified. Here, we report the functional analysis of redundant AP-1 μ-adaptins AP1M1 (also known as muB1) and AP1M2 (also known as muB2). Coimmunoprecipitation revealed that both AP1M2 and its less strongly expressed isoform AP1M1 are complexed with the large subunit γ-adaptin of AP-1. In addition, AP1M2 was localized at or near the trans-Golgi network. Knockout mutations of AP1M2 impaired pollen function and arrested plant growth whereas the ap1m1 ap1m2 double mutant was nearly pollen-lethal. At the cellular level, the absence of AP1M2 entailed inhibition of multiple trafficking pathways from the trans-Golgi network to the vacuole and to the plasma membrane in interphase and to the plane of cell division in cytokinesis. Thus, AP-1 is crucial in post-Golgi trafficking in plant cells and required for cell division and plant growth.
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