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Denninger P. RHO OF PLANTS signalling and the activating ROP GUANINE NUCLEOTIDE EXCHANGE FACTORS: specificity in cellular signal transduction in plants. JOURNAL OF EXPERIMENTAL BOTANY 2024; 75:3685-3699. [PMID: 38683617 PMCID: PMC11194304 DOI: 10.1093/jxb/erae196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 04/28/2024] [Indexed: 05/01/2024]
Abstract
Every cell constantly receives signals from its neighbours or the environment. In plants, most signals are perceived by RECEPTOR-LIKE KINASEs (RLKs) and then transmitted into the cell. The molecular switches RHO OF PLANTS (ROP) are critical proteins for polar signal transduction and regulate multiple cell polarity processes downstream of RLKs. Many ROP-regulating proteins and scaffold proteins of the ROP complex are known. However, the spatiotemporal ROP signalling complex composition is not yet understood. Moreover, how specificity is achieved in different ROP signalling pathways within one cell still needs to be determined. This review gives an overview of recent advances in ROP signalling and how specificity by downstream scaffold proteins can be achieved. The composition of the ROP signalling complexes is discussed, focusing on the possibility of the simultaneous presence of ROP activators and inactivators within the same complex to balance ROP activity. Furthermore, this review highlights the function of plant-specific ROP GUANINE NUCLEOTIDE EXCHANGE FACTORS polarizing ROP signalling and defining the specificity of the initiated ROP signalling pathway.
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Affiliation(s)
- Philipp Denninger
- Plant Systems Biology, School of Life Sciences, Technical University of Munich, Emil-Ramann-Strasse 8, 85354 Freising, Germany
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2
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Mulvey H, Dolan L. RHO of plant signaling was established early in streptophyte evolution. Curr Biol 2023; 33:5515-5525.e4. [PMID: 38039969 DOI: 10.1016/j.cub.2023.11.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 11/02/2023] [Accepted: 11/06/2023] [Indexed: 12/03/2023]
Abstract
The algal ancestors of land plants underwent a transition from a unicellular to a multicellular body plan.1 This transition likely took place early in streptophyte evolution, sometime after the divergence of the Chlorokybophyceae/Mesostigmatophyceae lineage, but before the divergence of the Klebsormidiophyceae lineage.2 How this transition was brought about is unknown; however, it was likely facilitated by the evolution of novel mechanisms to spatially regulate morphogenesis. In land plants, RHO of plant (ROP) signaling plays a conserved role in regulating polarized cell growth and cell division orientation to orchestrate morphogenesis.3,4,5,6,7,8 ROP constitutes a plant-specific subfamily of the RHO GTPases, which are more widely conserved throughout eukaryotes.9,10 Although the RHO family originated in early eukaryotes,11,12 how and when the ROP subfamily originated had remained elusive. Here, we demonstrate that ROP signaling was established early in the streptophyte lineage, sometime after the divergence of the Chlorokybophyceae/Mesostigmatophyceae lineage, but before the divergence of the Klebsormidiophyceae lineage. This period corresponds to when the unicellular-to-multicellular transition likely took place in the streptophytes. In addition to being critical for the complex morphogenesis of extant land plants, we speculate that ROP signaling contributed to morphological evolution in early streptophytes.
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Affiliation(s)
- Hugh Mulvey
- Department of Biology, University of Oxford, South Parks Road, Oxford OX1 3RB, UK; Gregor Mendel Institute of Molecular Plant Biology (GMI), Austrian Academy of Sciences, Vienna BioCenter (VBC), Dr. Bohr-Gasse 3, Vienna 1030, Austria
| | - Liam Dolan
- Department of Biology, University of Oxford, South Parks Road, Oxford OX1 3RB, UK; Gregor Mendel Institute of Molecular Plant Biology (GMI), Austrian Academy of Sciences, Vienna BioCenter (VBC), Dr. Bohr-Gasse 3, Vienna 1030, Austria.
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Kirchhelle C, Chow CM, Foucart C, Neto H, Stierhof YD, Kalde M, Walton C, Fricker M, Smith RS, Jérusalem A, Irani N, Moore I. The Specification of Geometric Edges by a Plant Rab GTPase Is an Essential Cell-Patterning Principle During Organogenesis in Arabidopsis. Dev Cell 2016; 36:386-400. [PMID: 26906735 PMCID: PMC4766369 DOI: 10.1016/j.devcel.2016.01.020] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 12/14/2015] [Accepted: 01/25/2016] [Indexed: 12/11/2022]
Abstract
Plant organogenesis requires control over division planes and anisotropic cell wall growth, which each require spatial patterning of cells. Polyhedral plant cells can display complex patterning in which individual faces are established as biochemically distinct domains by endomembrane trafficking. We now show that, during organogenesis, the Arabidopsis endomembrane system specifies an important additional cellular spatial domain: the geometric edges. Previously unidentified membrane vesicles lying immediately beneath the plasma membrane at cell edges were revealed through localization of RAB-A5c, a plant GTPase of the Rab family of membrane-trafficking regulators. Specific inhibition of RAB-A5c activity grossly perturbed cell geometry in developing lateral organs by interfering independently with growth anisotropy and cytokinesis without disrupting default membrane trafficking. The initial loss of normal cell geometry can be explained by a failure to maintain wall stiffness specifically at geometric edges. RAB-A5c thus meets a requirement to specify this cellular spatial domain during organogenesis.
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Affiliation(s)
- Charlotte Kirchhelle
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK
| | - Cheung-Ming Chow
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK
| | - Camille Foucart
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK
| | - Helia Neto
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK
| | - York-Dieter Stierhof
- Center for Plant Molecular Biology, Microscopy, University of Tübingen, Auf der Morgenstelle 32, 72076 Tübingen, Germany
| | - Monika Kalde
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK
| | - Carol Walton
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK
| | - Mark Fricker
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK
| | - Richard S Smith
- Department of Comparative and Developmental Genetics, Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, Cologne 50829, Germany
| | - Antoine Jérusalem
- Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, UK
| | - Niloufer Irani
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK
| | - Ian Moore
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK.
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Hanadate Y, Saito-Nakano Y, Nakada-Tsukui K, Nozaki T. Endoplasmic reticulum-resident Rab8A GTPase is involved in phagocytosis in the protozoan parasite Entamoeba histolytica. Cell Microbiol 2016; 18:1358-73. [PMID: 26807810 PMCID: PMC5071775 DOI: 10.1111/cmi.12570] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 12/31/2015] [Accepted: 01/19/2016] [Indexed: 12/20/2022]
Abstract
Phagocytosis is indispensable for the pathogenesis of the intestinal protozoan parasite Entamoeba histolytica. Here, we showed that in E. histolytica Rab8A, which is generally involved in trafficking from the trans‐Golgi network to the plasma membrane in other organisms but was previously identified in phagosomes of the amoeba in the proteomic analysis, primarily resides in the endoplasmic reticulum (ER) and participates in phagocytosis. We demonstrated that down‐regulation of EhRab8A by small antisense RNA‐mediated transcriptional gene silencing remarkably reduced adherence and phagocytosis of erythrocytes, bacteria and carboxylated latex beads. Surface biotinylation followed by SDS‐PAGE analysis revealed that the surface expression of several proteins presumably involved in target recognition was reduced in the EhRab8A gene‐silenced strain. Further, overexpression of wild‐type EhRab8A augmented phagocytosis, whereas expression of the dominant‐negative form of EhRab8A resulted in reduced phagocytosis. These results indicated that EhRab8A regulates transport of surface receptor(s) for the prey from the ER to the plasma membrane. To our knowledge, this is the first report that the ER‐resident Rab GTPase is involved in phagocytosis through the regulation of trafficking of a surface receptor, supporting a premise of direct involvement of the ER in phagocytosis.
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Affiliation(s)
- Yuki Hanadate
- Department of Parasitology, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo, 162-8640, Japan.,Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8572, Japan
| | - Yumiko Saito-Nakano
- Department of Parasitology, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo, 162-8640, Japan
| | - Kumiko Nakada-Tsukui
- Department of Parasitology, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo, 162-8640, Japan
| | - Tomoyoshi Nozaki
- Department of Parasitology, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo, 162-8640, Japan. .,Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8572, Japan.
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Yalovsky S. Protein lipid modifications and the regulation of ROP GTPase function. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:1617-24. [PMID: 25711710 DOI: 10.1093/jxb/erv057] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
In eukaryotes, the RHO superfamily of small G-proteins is implicated in the regulation of cell polarity and growth. Rho of Plants (ROPs)/RACs are plant-specific Rho family proteins that have been shown to regulate cell polarity, auxin transport and responses, ABA signalling, and response to pathogens. A hallmark of ROP/RAC function is their localization in specific plasma membrane domains. This short review focuses on the mechanisms responsible for membrane interactions of ROPs/RACs and how they affect ROP/RAC function.
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Affiliation(s)
- Shaul Yalovsky
- Department of Molecular Biology and Ecology of Plants, Tel Aviv University, Tel Aviv 69978, Israel
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Price HP, Hodgkinson MR, Wright MH, Tate EW, Smith BA, Carrington M, Stark M, Smith DF. A role for the vesicle-associated tubulin binding protein ARL6 (BBS3) in flagellum extension in Trypanosoma brucei. BIOCHIMICA ET BIOPHYSICA ACTA 2012; 1823:1178-91. [PMID: 22609302 PMCID: PMC3793860 DOI: 10.1016/j.bbamcr.2012.05.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Revised: 04/23/2012] [Accepted: 05/05/2012] [Indexed: 11/17/2022]
Abstract
The small GTPase Arl6 is implicated in the ciliopathic human genetic disorder Bardet-Biedl syndrome, acting at primary cilia in recruitment of the octomeric BBSome complex, which is required for specific trafficking events to and from the cilium in eukaryotes. Here we describe functional characterisation of Arl6 in the flagellated model eukaryote Trypanosoma brucei, which requires motility for viability. Unlike human Arl6 which has a ciliary localisation, TbARL6 is associated with electron-dense vesicles throughout the cell body following co-translational modification by N-myristoylation. Similar to the related protein ARL-3A in T. brucei, modulation of expression of ARL6 by RNA interference does not prevent motility but causes a significant reduction in flagellum length. Tubulin is identified as an ARL6 interacting partner, suggesting that ARL6 may act as an anchor between vesicles and cytoplasmic microtubules. We provide evidence that the interaction between ARL6 and the BBSome is conserved in unicellular eukaryotes. Overexpression of BBS1 leads to translocation of endogenous ARL6 to the site of exogenous BBS1 at the flagellar pocket. Furthermore, a combination of BBS1 overexpression and ARL6 RNAi has a synergistic inhibitory effect on cell growth. Our findings indicate that ARL6 in trypanosomes contributes to flagellum biogenesis, most likely through an interaction with the BBSome.
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Key Words
- arf, adp-ribosylation factor
- arl, adp-ribosylation factor-like
- arl6ip, arl6 interacting protein
- bbs, bardet–biedl syndrome
- bbs1, bardet–biedl syndrome 1 protein
- bsf, bloodstream form
- cona, concanavalin a
- gef, guanine nucleotide exchange factor
- gpcr, g-protein coupled receptor
- hrg4, human retinal gene 4
- ift, intraflagellar transport
- itc, isothermal titration calorimetry
- mant, n-methylanthraniloyl
- map2, microtubule associated protein 2
- nes, nuclear export signal
- nls, nuclear localisation signal
- nmt, myristoyl-coa:protein n-myristoyltransferase
- pcf, procyclic form
- pcm1, pericentriolar material 1
- pfr, paraflagellar rod
- pm, plasma membrane
- rnai, rna interference
- rp2, retinitis pigmentosa protein 2
- tap, tandem affinity purification
- tiem, transmission immuno-electron microscopy
- trypanosoma brucei
- arl6
- bbsome
- bbs1
- flagellum
- tubulin
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Affiliation(s)
- Helen P Price
- Centre for Immunology and Infection, Department of Biology, University of York, Heslington, York YO10 5YW, UK.
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Mucha E, Fricke I, Schaefer A, Wittinghofer A, Berken A. Rho proteins of plants – Functional cycle and regulation of cytoskeletal dynamics. Eur J Cell Biol 2011; 90:934-43. [PMID: 21277045 DOI: 10.1016/j.ejcb.2010.11.009] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Revised: 11/25/2010] [Accepted: 11/25/2010] [Indexed: 10/24/2022] Open
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Elias M. Patterns and processes in the evolution of the eukaryotic endomembrane system. Mol Membr Biol 2010; 27:469-89. [DOI: 10.3109/09687688.2010.521201] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Recycling domains in plant cell morphogenesis: small GTPase effectors, plasma membrane signalling and the exocyst. Biochem Soc Trans 2010; 38:723-8. [PMID: 20298250 DOI: 10.1042/bst0380723] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The Rho/Rop small GTPase regulatory module is central for initiating exocytotically ACDs (active cortical domains) in plant cell cortex, and a growing array of Rop regulators and effectors are being discovered in plants. Structural membrane phospholipids are important constituents of cells as well as signals, and phospholipid-modifying enzymes are well known effectors of small GTPases. We have shown that PLDs (phospholipases D) and their product, PA (phosphatidic acid), belong to the regulators of the secretory pathway in plants. We have also shown that specific NOXs (NADPH oxidases) producing ROS (reactive oxygen species) are involved in cell growth as exemplified by pollen tubes and root hairs. Most plant cells exhibit several distinct plasma membrane domains (ACDs), established and maintained by endocytosis/exocytosis-driven membrane protein recycling. We proposed recently the concept of a 'recycling domain' (RD), uniting the ACD and the connected endosomal recycling compartment (endosome), as a dynamic spatiotemporal entity. We have described a putative GTPase-effector complex exocyst involved in exocytic vesicle tethering in plants. Owing to the multiplicity of its Exo70 subunits, this complex, along with many RabA GTPases (putative recycling endosome organizers), may belong to core regulators of RD organization in plants.
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Thomas C, Berken A. Structure and Function of ROPs and their GEFs. INTEGRATED G PROTEINS SIGNALING IN PLANTS 2010. [DOI: 10.1007/978-3-642-03524-1_3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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12
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Elias M, Patron NJ, Keeling PJ. The RAB family GTPase Rab1A from Plasmodium falciparum defines a unique paralog shared by chromalveolates and rhizaria. J Eukaryot Microbiol 2009; 56:348-56. [PMID: 19602080 DOI: 10.1111/j.1550-7408.2009.00408.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The RAB GTPases, which are involved in regulation of endomembrane trafficking, exhibit a complex but incompletely understood evolutionary history. We elucidated the evolution of the RAB1 subfamily ancestrally implicated in the endoplasmic reticulum-to-Golgi traffic. We found that RAB1 paralogs have been generated over the course of eukaryotic evolution, with some duplications coinciding with the advent of major eukaryotic lineages (e.g. Metazoa, haptophytes). We also identified a unique, derived RAB1 paralog, orthologous to the Plasmodium Rab1A, that occurs in stramenopiles, alveolates, and Rhizaria, represented by the chlorarachniophyte Gymnochlora stellata. This finding is consistent with the recently documented existence of a major eukaryotic clade ("SAR") comprising these three lineages. We further found a Rab1A-like protein in the cryptophyte Guillardia theta, but it exhibits unusual features among RAB proteins: absence of a C-terminal prenylation motif and an N-terminal extension with two MSP domains; and its phylogenetic relationships could not be established convincingly due to its divergent nature. Our results nevertheless point to a unique membrane trafficking pathway shared by at least some lineages of chromalveolates and Rhizaria, an insight that has implications towards interpreting the early evolution of eukaryotes and the endomembrane system.
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Affiliation(s)
- Marek Elias
- Department of Botany, Faculty of Science, Charles University in Prague, Prague, Czech Republic.
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