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Kalot R, Sentell Z, Kitzler TM, Torban E. Primary cilia and actin regulatory pathways in renal ciliopathies. FRONTIERS IN NEPHROLOGY 2024; 3:1331847. [PMID: 38292052 PMCID: PMC10824913 DOI: 10.3389/fneph.2023.1331847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Accepted: 12/20/2023] [Indexed: 02/01/2024]
Abstract
Ciliopathies are a group of rare genetic disorders caused by defects to the structure or function of the primary cilium. They often affect multiple organs, leading to brain malformations, congenital heart defects, and anomalies of the retina or skeletal system. Kidney abnormalities are among the most frequent ciliopathic phenotypes manifesting as smaller, dysplastic, and cystic kidneys that are often accompanied by renal fibrosis. Many renal ciliopathies cause chronic kidney disease and often progress to end-stage renal disease, necessitating replacing therapies. There are more than 35 known ciliopathies; each is a rare hereditary condition, yet collectively they account for a significant proportion of chronic kidney disease worldwide. The primary cilium is a tiny microtubule-based organelle at the apex of almost all vertebrate cells. It serves as a "cellular antenna" surveying environment outside the cell and transducing this information inside the cell to trigger multiple signaling responses crucial for tissue morphogenesis and homeostasis. Hundreds of proteins and unique cellular mechanisms are involved in cilia formation. Recent evidence suggests that actin remodeling and regulation at the base of the primary cilium strongly impacts ciliogenesis. In this review, we provide an overview of the structure and function of the primary cilium, focusing on the role of actin cytoskeleton and its regulators in ciliogenesis. We then describe the key clinical, genetic, and molecular aspects of renal ciliopathies. We highlight what is known about actin regulation in the pathogenesis of these diseases with the aim to consider these recent molecular findings as potential therapeutic targets for renal ciliopathies.
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Affiliation(s)
- Rita Kalot
- Department of Medicine and Department of Physiology, McGill University, Montreal, QC, Canada
- The Research Institute of the McGill University Health Center, Montreal, QC, Canada
| | - Zachary Sentell
- Department of Human Genetics, McGill University, Montreal, QC, Canada
| | - Thomas M. Kitzler
- Department of Human Genetics, McGill University, Montreal, QC, Canada
- McGill University Health Center, Montreal, QC, Canada
| | - Elena Torban
- Department of Medicine and Department of Physiology, McGill University, Montreal, QC, Canada
- The Research Institute of the McGill University Health Center, Montreal, QC, Canada
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2
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Amack JD. Structures and functions of cilia during vertebrate embryo development. Mol Reprod Dev 2022; 89:579-596. [PMID: 36367893 PMCID: PMC9805515 DOI: 10.1002/mrd.23650] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 10/05/2022] [Accepted: 10/28/2022] [Indexed: 11/13/2022]
Abstract
Cilia are hair-like structures that project from the surface of cells. In vertebrates, most cells have an immotile primary cilium that mediates cell signaling, and some specialized cells assemble one or multiple cilia that are motile and beat synchronously to move fluids in one direction. Gene mutations that alter cilia structure or function cause a broad spectrum of disorders termed ciliopathies that impact virtually every system in the body. A wide range of birth defects associated with ciliopathies underscores critical functions for cilia during embryonic development. In many cases, the mechanisms underlying cilia functions during development and disease remain poorly understood. This review describes different types of cilia in vertebrate embryos and discusses recent research results from diverse model systems that provide novel insights into how cilia form and function during embryo development. The work discussed here not only expands our understanding of in vivo cilia biology, but also opens new questions about cilia and their roles in establishing healthy embryos.
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Affiliation(s)
- Jeffrey D. Amack
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York, USA,,BioInspired Syracuse: Institute for Material and Living Systems, Syracuse, New York, USA
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3
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Cui X, Wang S, Huang Y, Ding X, Wang Z, Zheng L, Bi Y, Ge F, Zhu L, Yuan M, Yalovsky S, Fu Y. Arabidopsis SYP121 acts as an ROP2 effector in the regulation of root hair tip growth. MOLECULAR PLANT 2022; 15:1008-1023. [PMID: 35488430 DOI: 10.1016/j.molp.2022.04.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Revised: 04/04/2022] [Accepted: 04/25/2022] [Indexed: 06/14/2023]
Abstract
Tip growth is an extreme form of polarized cell expansion that occurs in all eukaryotic kingdoms to generate highly elongated tubular cells with specialized functions, including fungal hyphae, animal neurons, plant pollen tubes, and root hairs (RHs). RHs are tubular structures that protrude from the root epidermis to facilitate water and nutrient uptake, microbial interactions, and plant anchorage. RH tip growth requires polarized vesicle targeting and active exocytosis at apical growth sites. However, how apical exocytosis is spatially and temporally controlled during tip growth remains elusive. Here, we report that the Qa-Soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) SYP121 acts as an effector of Rho of Plants 2 (ROP2), mediating the regulation of RH tip growth. We show that active ROP2 promotes SYP121 targeting to the apical plasma membrane. Moreover, ROP2 directly interacts with SYP121 and promotes the interaction between SYP121 and the R-SNARE VAMP722 to form a SNARE complex, probably by facilitating the release of the Sec1/Munc18 protein SEC11, which suppresses the function of SYP121. Thus, the ROP2-SYP121 pathway facilitates exocytic trafficking during RH tip growth. Our study uncovers a direct link between an ROP GTPase and vesicular trafficking and a new mechanism for the control of apical exocytosis, whereby ROP GTPase signaling spatially regulates SNARE complex assembly and the polar distribution of a Q-SNARE.
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Affiliation(s)
- Xiankui Cui
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Shuwei Wang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Yaohui Huang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Xuening Ding
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Zirong Wang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Lidan Zheng
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Yujing Bi
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Fanghui Ge
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Lei Zhu
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China; Joint Laboratory for International Cooperation in Crop Molecular Breeding, Ministry of Education, China Agricultural University, Beijing 100193, China
| | - Ming Yuan
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Shaul Yalovsky
- Department of Plant Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Ying Fu
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China; Joint Laboratory for International Cooperation in Crop Molecular Breeding, Ministry of Education, China Agricultural University, Beijing 100193, China.
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4
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Pang L, Ma Z, Zhang X, Huang Y, Li R, Miao Y, Li R. The small GTPase RABA2a recruits SNARE proteins to regulate the secretory pathway in parallel with the exocyst complex in Arabidopsis. MOLECULAR PLANT 2022; 15:398-418. [PMID: 34798312 DOI: 10.1016/j.molp.2021.11.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 10/24/2021] [Accepted: 11/12/2021] [Indexed: 05/22/2023]
Abstract
Delivery of proteins to the plasma membrane occurs via secretion, which requires tethering, docking, priming, and fusion of vesicles. In yeast and mammalian cells, an evolutionarily conserved RAB GTPase activation cascade functions together with the exocyst and SNARE proteins to coordinate vesicle transport with fusion at the plasma membrane. However, it is unclear whether this is the case in plants. In this study, we show that the small GTPase RABA2a recruits and interacts with the VAMP721/722-SYP121-SNAP33 SNARE ternary complex for membrane fusion. Through immunoprecipitation coupled with mass spectrometry analysis followed by the validatation with a series of biochemical assays, we identified the SNARE proteins VAMP721 and SYP121 as the interactors and downstream effectors of RABA2a. Further expreiments showed that RABA2a interacts with all members of the SNARE complex in its GTP-bound form and modulates the assembly of the VAMP721/722-SYP121-SNAP33 SNARE ternary complex. Intriguingly, we did not observe the interaction of the exocyst subunits with either RABA2a or theSNARE proteins in several different experiments. Neither RABA2a inactivation affects the subcellular localization or assembly of the exocystnor the exocyst subunit mutant exo84b shows the disrupted RABA2a-SNARE association or SNARE assembly, suggesting that the RABA2a-SNARE- and exocyst-mediated secretory pathways are largely independent. Consistently, our live imaging experiments reveal that the two sets of proteins follow non-overlapping trafficking routes, and genetic and cell biologyanalyses indicate that the two pathways select different cargos. Finally, we demonstrate that the plant-specific RABA2a-SNARE pathway is essential for the maintenance of potassium homeostasis in Arabisopsis seedlings. Collectively, our findings imply that higher plants might have generated different endomembrane sorting pathways during evolution and may enable the highly conserved endomembrane proteins to participate in plant-specific trafficking mechanisms for adaptation to the changing environment.
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Affiliation(s)
- Lei Pang
- Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Institute of Plant and Food Science, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China
| | - Zhiming Ma
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Xi Zhang
- College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, China
| | - Yuanzhi Huang
- Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Institute of Plant and Food Science, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China
| | - Ruili Li
- College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, China
| | - Yansong Miao
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Ruixi Li
- Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Institute of Plant and Food Science, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China.
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5
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García P, Coll PM, Del Rey F, Geli MI, Pérez P, Vázquez de Aldana CR, Encinar Del Dedo J. Eng2, a new player involved in feedback loop regulation of Cdc42 activity in fission yeast. Sci Rep 2021; 11:17872. [PMID: 34504165 PMCID: PMC8429772 DOI: 10.1038/s41598-021-97311-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 08/05/2021] [Indexed: 11/09/2022] Open
Abstract
Cell polarity and morphogenesis are regulated by the small GTPase Cdc42. Even though major advances have been done in the field during the last years, the molecular details leading to its activation in particular cellular contexts are not completely understood. In fission yeast, the β(1,3)-glucanase Eng2 is a "moonlighting protein" with a dual function, acting as a hydrolase during spore dehiscence, and as component of the endocytic machinery in vegetative cells. Here, we report that Eng2 plays a role in Cdc42 activation during polarized growth through its interaction with the scaffold protein Scd2, which brings Cdc42 together with its guanine nucleotide exchange factor (GEF) Scd1. eng2Δ mutant cells have defects in activation of the bipolar growth (NETO), remaining monopolar during all the cell cycle. In the absence of Eng2 the accumulation of Scd1 and Scd2 at the poles is reduced, the levels of Cdc42 activation decrease, and the Cdc42 oscillatory behavior, associated with bipolar growth in wild type cells, is altered. Furthermore, overexpression of Eng2 partially rescues the growth and polarity defects of a cdc42-L160S mutant. Altogether, our work unveils a new factor regulating the activity of Cdc42, which could potentially link the polarity and endocytic machineries.
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Affiliation(s)
- Patricia García
- Instituto de Biología Funcional y Genómica, CSIC/Universidad de Salamanca, c/ Zacarías González 2, 37007, Salamanca, Spain
| | - Pedro M Coll
- Instituto de Biología Funcional y Genómica, CSIC/Universidad de Salamanca, c/ Zacarías González 2, 37007, Salamanca, Spain
| | - Francisco Del Rey
- Instituto de Biología Funcional y Genómica, CSIC/Universidad de Salamanca, c/ Zacarías González 2, 37007, Salamanca, Spain
| | - M Isabel Geli
- Institute for Molecular Biology of Barcelona (CSIC), Baldiri Reixac 15, 08028, Barcelona, Spain
| | - Pilar Pérez
- Instituto de Biología Funcional y Genómica, CSIC/Universidad de Salamanca, c/ Zacarías González 2, 37007, Salamanca, Spain
| | - Carlos R Vázquez de Aldana
- Instituto de Biología Funcional y Genómica, CSIC/Universidad de Salamanca, c/ Zacarías González 2, 37007, Salamanca, Spain.
| | - Javier Encinar Del Dedo
- Instituto de Biología Funcional y Genómica, CSIC/Universidad de Salamanca, c/ Zacarías González 2, 37007, Salamanca, Spain.
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6
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Santana-Molina C, Gutierrez F, Devos DP. Homology and Modular Evolution of CATCHR at the Origin of the Eukaryotic Endomembrane System. Genome Biol Evol 2021; 13:6290715. [PMID: 34061181 PMCID: PMC8290106 DOI: 10.1093/gbe/evab125] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/27/2021] [Indexed: 01/02/2023] Open
Abstract
The membrane trafficking is an essential process of eukaryotic cells, as it manages vesicular trafficking toward different parts of the cell. In this process, membrane fusions between vesicles and target membranes are mediated by several factors, including the multisubunit tethering complexes. One type of multisubunit tethering complex, the complexes associated with tethering containing helical rods (CATCHR), encompasses the exocyst, COG, GARP, and DSL1 complexes. The CATCHR share similarities at sequence, structural, and protein-complex organization level although their actual relationship is still poorly understood. In this study, we have re-evaluated CATCHR at different levels, demonstrating that gene duplications followed by neofunctionalization, were key for their origin. Our results, reveals that there are specific homology relationships and parallelism within and between the CATCHR suggesting that most of these complexes are composed by modular tetramers of four different kinds of proteins, three of them having a clear common origin. The extension of CATCHR family occurred concomitantly with the protein family expansions of their molecular partners, such as small GTPases and SNAREs, among others, and likely providing functional specificity. Our results provide novel insights into the structural organization and mechanism of action of CATCHR, with implications for the evolution of the endomembrane system of eukaryotes and promoting CATCHR as ideal candidates to study the evolution of multiprotein complexes.
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Affiliation(s)
- Carlos Santana-Molina
- Centro Andaluz de Biología del Desarrollo, Consejo Superior de Investigaciones Científicas/Universidad Pablo de Olavide/Junta de Andalucía, Seville, Spain
| | - Fernando Gutierrez
- Centro Andaluz de Biología del Desarrollo, Consejo Superior de Investigaciones Científicas/Universidad Pablo de Olavide/Junta de Andalucía, Seville, Spain.,Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Damien P Devos
- Centro Andaluz de Biología del Desarrollo, Consejo Superior de Investigaciones Científicas/Universidad Pablo de Olavide/Junta de Andalucía, Seville, Spain
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7
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Luscher A, Fröhlich F, Barisch C, Littlewood C, Metcalfe J, Leuba F, Palma A, Pirruccello M, Cesareni G, Stagi M, Walther TC, Soldati T, De Camilli P, Swan LE. Lowe syndrome-linked endocytic adaptors direct membrane cycling kinetics with OCRL in Dictyostelium discoideum. Mol Biol Cell 2019; 30:2268-2282. [PMID: 31216233 PMCID: PMC6743453 DOI: 10.1091/mbc.e18-08-0510] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Mutations of the inositol 5-phosphatase OCRL cause Lowe syndrome (LS), characterized by congenital cataract, low IQ, and defective kidney proximal tubule resorption. A key subset of LS mutants abolishes OCRL’s interactions with endocytic adaptors containing F&H peptide motifs. Converging unbiased methods examining human peptides and the unicellular phagocytic organism Dictyostelium discoideum reveal that, like OCRL, the Dictyostelium OCRL orthologue Dd5P4 binds two proteins closely related to the F&H proteins APPL1 and Ses1/2 (also referred to as IPIP27A/B). In addition, a novel conserved F&H interactor was identified, GxcU (in Dictyostelium) and the Cdc42-GEF FGD1-related F-actin binding protein (Frabin) (in human cells). Examining these proteins in D. discoideum, we find that, like OCRL, Dd5P4 acts at well-conserved and physically distinct endocytic stations. Dd5P4 functions in coordination with F&H proteins to control membrane deformation at multiple stages of endocytosis and suppresses GxcU-mediated activity during fluid-phase micropinocytosis. We also reveal that OCRL/Dd5P4 acts at the contractile vacuole, an exocytic osmoregulatory organelle. We propose F&H peptide-containing proteins may be key modifiers of LS phenotypes.
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Affiliation(s)
- Alexandre Luscher
- Department of Biochemistry, Faculty of Science, University of Geneva, 1211 Geneva-4, Switzerland
| | - Florian Fröhlich
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510.,Department of Genetics and Complex Diseases, Harvard School of Public Health, and Department of Cell Biology, Harvard Medical School, Howard Hughes Medical Institute, Boston, MA 02115
| | - Caroline Barisch
- Department of Biochemistry, Faculty of Science, University of Geneva, 1211 Geneva-4, Switzerland
| | - Clare Littlewood
- Department of Cellular and Molecular Physiology, University of Liverpool, L69 3BX Liverpool, United Kingdom
| | - Joe Metcalfe
- Department of Cellular and Molecular Physiology, University of Liverpool, L69 3BX Liverpool, United Kingdom
| | - Florence Leuba
- Department of Biochemistry, Faculty of Science, University of Geneva, 1211 Geneva-4, Switzerland
| | - Anita Palma
- Department of Biology, University of Rome, 00133 Rome, Italy
| | - Michelle Pirruccello
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510.,Howard Hughes Medical Institute, Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale University School of Medicine, New Haven, CT 06510
| | - Gianni Cesareni
- Department of Biology, University of Rome, 00133 Rome, Italy
| | - Massimiliano Stagi
- Department of Cellular and Molecular Physiology, University of Liverpool, L69 3BX Liverpool, United Kingdom
| | - Tobias C Walther
- Department of Genetics and Complex Diseases, Harvard School of Public Health, and Department of Cell Biology, Harvard Medical School, Howard Hughes Medical Institute, Boston, MA 02115
| | - Thierry Soldati
- Department of Biochemistry, Faculty of Science, University of Geneva, 1211 Geneva-4, Switzerland
| | - Pietro De Camilli
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510.,Howard Hughes Medical Institute, Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale University School of Medicine, New Haven, CT 06510.,Department of Neuroscience and Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT 06510
| | - Laura E Swan
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510.,Howard Hughes Medical Institute, Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale University School of Medicine, New Haven, CT 06510.,Department of Cellular and Molecular Physiology, University of Liverpool, L69 3BX Liverpool, United Kingdom
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8
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Cole RA, Peremyslov VV, Van Why S, Moussaoui I, Ketter A, Cool R, Moreno MA, Vejlupkova Z, Dolja VV, Fowler JE. A broadly conserved NERD genetically interacts with the exocyst to affect root growth and cell expansion. JOURNAL OF EXPERIMENTAL BOTANY 2018; 69:3625-3637. [PMID: 29722827 PMCID: PMC6022600 DOI: 10.1093/jxb/ery162] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 04/24/2018] [Indexed: 05/10/2023]
Abstract
The exocyst, a conserved, octameric protein complex, helps mediate secretion at the plasma membrane, facilitating specific developmental processes that include control of root meristem size, cell elongation, and tip growth. A genetic screen for second-site enhancers in Arabidopsis identified NEW ENHANCER of ROOT DWARFISM1 (NERD1) as an exocyst interactor. Mutations in NERD1 combined with weak exocyst mutations in SEC8 and EXO70A1 result in a synergistic reduction in root growth. Alone, nerd1 alleles modestly reduce primary root growth, both by shortening the root meristem and by reducing cell elongation, but also result in a slight increase in root hair length, bulging, and rupture. NERD1 was identified molecularly as At3g51050, which encodes a transmembrane protein of unknown function that is broadly conserved throughout the Archaeplastida. A functional NERD1-GFP fusion localizes to the Golgi, in a pattern distinct from the plasma membrane-localized exocyst, arguing against a direct NERD1-exocyst interaction. Structural modeling suggests the majority of the protein is positioned in the lumen, in a β-propeller-like structure that has some similarity to proteins that bind polysaccharides. We suggest that NERD1 interacts with the exocyst indirectly, possibly affecting polysaccharides destined for the cell wall, and influencing cell wall characteristics in a developmentally distinct manner.
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Affiliation(s)
- Rex A Cole
- Department of Botany and Plant Pathology and Center for Genome Research and Biocomputing, Oregon State University, Corvallis, OR, USA
| | - Valera V Peremyslov
- Department of Botany and Plant Pathology and Center for Genome Research and Biocomputing, Oregon State University, Corvallis, OR, USA
| | - Savannah Van Why
- Department of Botany and Plant Pathology and Center for Genome Research and Biocomputing, Oregon State University, Corvallis, OR, USA
| | - Ibrahim Moussaoui
- Department of Botany and Plant Pathology and Center for Genome Research and Biocomputing, Oregon State University, Corvallis, OR, USA
| | - Ann Ketter
- Department of Botany and Plant Pathology and Center for Genome Research and Biocomputing, Oregon State University, Corvallis, OR, USA
| | - Renee Cool
- Department of Botany and Plant Pathology and Center for Genome Research and Biocomputing, Oregon State University, Corvallis, OR, USA
| | - Matthew Andres Moreno
- Department of Botany and Plant Pathology and Center for Genome Research and Biocomputing, Oregon State University, Corvallis, OR, USA
| | - Zuzana Vejlupkova
- Department of Botany and Plant Pathology and Center for Genome Research and Biocomputing, Oregon State University, Corvallis, OR, USA
| | - Valerian V Dolja
- Department of Botany and Plant Pathology and Center for Genome Research and Biocomputing, Oregon State University, Corvallis, OR, USA
| | - John E Fowler
- Department of Botany and Plant Pathology and Center for Genome Research and Biocomputing, Oregon State University, Corvallis, OR, USA
- Correspondence:
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9
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Weber MM, Faris R, van Schaik EJ, Samuel JE. Identification and characterization of arginine finger-like motifs, and endosome-lysosome basolateral sorting signals within the Coxiella burnetii type IV secreted effector protein CirA. Microbes Infect 2018; 20:302-307. [PMID: 29331581 PMCID: PMC6021133 DOI: 10.1016/j.micinf.2017.12.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2017] [Revised: 10/17/2017] [Accepted: 12/20/2017] [Indexed: 01/20/2023]
Abstract
Coxiella burnetii is an obligate intracellular pathogen that replicates in an endolysosome-like compartment termed the Coxiella-containing vacuole (CCV). Formation of this unique replicative niche requires delivery of bacterial effector proteins into the host cytosol where they mediate crucial interactions with the host. We previously identified an essential Dot/Icm effector, CirA that is required for intracellular replication and CCV formation. Furthermore, CirA was shown to stimulate the GTPase activity of RhoA in vitro. In the current study, we used a bioinformatics-guided approach and identified three arginine finger-like motifs, often found in Rho GTPase-activating proteins (GAPs) and endosome-lysosome basolateral sorting signals associated with vesicle trafficking. When expressed in mammalian cells, mutation of either endosome-lysosome-basolateral sorting signals or the arginine finger-like motifs rescued stress phenotypes and decreased plasma membrane localization of ectopically expressed CirA. We further demonstrate that endosome-lysosome sorting signals are required for co-localization with Rab5 and Rab7. Collectively our data indicate that arginine finger-like motifs and endosome-lysosome-basolateral sorting signals within CirA are essential for interaction with the host cytoskeleton.
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Affiliation(s)
- Mary M Weber
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, College of Medicine, Bryan, TX, 77807, USA
| | - Robert Faris
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, College of Medicine, Bryan, TX, 77807, USA
| | - Erin J van Schaik
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, College of Medicine, Bryan, TX, 77807, USA
| | - James E Samuel
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, College of Medicine, Bryan, TX, 77807, USA.
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10
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Satnav for cells: Destination membrane fusion. Cell Calcium 2017; 68:14-23. [PMID: 29129204 DOI: 10.1016/j.ceca.2017.10.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 09/20/2017] [Accepted: 10/07/2017] [Indexed: 11/23/2022]
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11
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Estravís M, Rincón SA, Portales E, Pérez P, Santos B. Cdc42 activation state affects its localization and protein levels in fission yeast. MICROBIOLOGY-SGM 2017; 163:1156-1166. [PMID: 28742002 DOI: 10.1099/mic.0.000503] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Rho GTPases control polarized cell growth and are well-known regulators of exocytic and endocytic processes. Cdc42 is an essential GTPase, conserved from yeast to humans, that is critical for cell polarization. Cdc42 is negatively regulated by the GTPase-activating proteins (GAPs) and the GDP dissociation inhibitors (GDIs), and positively regulated by guanine nucleotide exchange factors (GEFs). Cdc42 GTPase can be found in a GTP- or GDP-bound state, which determines the ability to bind downstream effector proteins and activate signalling pathways. Only GTP-bound Cdc42 is active. In this study we have analysed the localization of the different nucleotide-bound states of Cdc42 in Schizosaccharomyces pombe: the wild-type Cdc42 protein that cycles between an active and inactive form, the Cdc42G12V form that is permanently bound to GTP and the Cdc42T17N form that is constitutively inactive. Our results indicate that Cdc42 localizes to several membrane compartments in the cell and this localization is mediated by its C-terminal prenylation. Constitutively active Cdc42 localizes mainly to the plasma membrane and concentrates at the growing tips where it is considerably less dynamic than wild-type or GDP-bound Cdc42. Additionally we show that the activation state of Cdc42 also participates in the regulation of its protein levels mediated by endocytosis and by the exocyst complex.
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Affiliation(s)
- Miguel Estravís
- Instituto de Biología Funcional y Genómica (IBFG), Consejo Superior de Investigaciones Científicas, University of Salamanca, 37007 Salamanca, Spain
| | - Sergio Antonio Rincón
- Instituto de Biología Funcional y Genómica (IBFG), Consejo Superior de Investigaciones Científicas, University of Salamanca, 37007 Salamanca, Spain.,Present address: Institut Curie, Centre de Recherche, PSL Research University, CNRS UMR144, F-75248 Paris, France
| | - Elvira Portales
- Instituto de Biología Funcional y Genómica (IBFG), Consejo Superior de Investigaciones Científicas, University of Salamanca, 37007 Salamanca, Spain
| | - Pilar Pérez
- Instituto de Biología Funcional y Genómica (IBFG), Consejo Superior de Investigaciones Científicas, University of Salamanca, 37007 Salamanca, Spain
| | - Beatriz Santos
- Instituto de Biología Funcional y Genómica (IBFG), Consejo Superior de Investigaciones Científicas, University of Salamanca, 37007 Salamanca, Spain.,Departamento de Microbiología y Genética, University of Salamanca, 37007 Salamanca, Spain
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12
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Xiao L, Zheng K, Lv X, Hou J, Xu L, Zhao Y, Song F, Fan Y, Cao H, Zhang W, Hong X, Zhan YY, Hu T. Exo70 is an independent prognostic factor in colon cancer. Sci Rep 2017; 7:5039. [PMID: 28698570 PMCID: PMC5505949 DOI: 10.1038/s41598-017-05308-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 05/26/2017] [Indexed: 12/31/2022] Open
Abstract
Exo70, a key component of the Exocyst complex, plays important roles in human cancer progression beyond exocytosis. However, the expression of Exo70 and its prognostic value for patients with colon cancer has not been well investigated to date. In this study, we observed that the mRNA and protein levels of Exo70 were upregulated in 11 of 13 colon cancer tissues, compared with their normal counterparts, which was validated by immunohistochemical analysis in a tissue microarray containing 89 pairs of colon cancer tissues and the matched adjacent normal tissues. Statistical analysis revealed that Exo70 expression is positively correlated with tumor size, invasion depth, TNM stage and distant metastasis. Kaplan-Meier survival analysis showed that colon cancer patients with higher Exo70 expression have a poorer clinical outcome than those with lower Exo70 expression. Multivariate Cox regression analysis revealed that Exo70, age and distant metastasis were there independent prognostic factors for overall survival rate of colon cancer patients. Through gain- and loss of Exo70 in colon cancer cells, we found that Exo70 could enhance the migration ability of colon cancer cells. Taken together, our studies revealed that Exo70 might be a promising negative prognostic factor and a potential therapeutic target for colon cancer.
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Affiliation(s)
- Li Xiao
- Cancer Research Center, Xiamen University Medical College, Xiamen, 361102, Fujian Province, P.R. China
- Department of Oncology, Zhongshan Hospital Affiliated to Xiamen University, Xiamen, 361004, Fujian Province, P.R. China
| | - Kaifeng Zheng
- Cancer Research Center, Xiamen University Medical College, Xiamen, 361102, Fujian Province, P.R. China
| | - Xia Lv
- Department of Oncology, Zhongshan Hospital Affiliated to Xiamen University, Xiamen, 361004, Fujian Province, P.R. China
| | - Jihuan Hou
- Cancer Research Center, Xiamen University Medical College, Xiamen, 361102, Fujian Province, P.R. China
| | - Liang Xu
- Cancer Research Center, Xiamen University Medical College, Xiamen, 361102, Fujian Province, P.R. China
| | - Yujie Zhao
- Cancer Research Center, Xiamen University Medical College, Xiamen, 361102, Fujian Province, P.R. China
| | - Fei Song
- Cancer Research Center, Xiamen University Medical College, Xiamen, 361102, Fujian Province, P.R. China
| | - Yaqiong Fan
- Cancer Research Center, Xiamen University Medical College, Xiamen, 361102, Fujian Province, P.R. China
| | - Hanwei Cao
- Cancer Research Center, Xiamen University Medical College, Xiamen, 361102, Fujian Province, P.R. China
| | - Wenqing Zhang
- Cancer Research Center, Xiamen University Medical College, Xiamen, 361102, Fujian Province, P.R. China
| | - Xiaoting Hong
- Cancer Research Center, Xiamen University Medical College, Xiamen, 361102, Fujian Province, P.R. China
| | - Yan-Yan Zhan
- Cancer Research Center, Xiamen University Medical College, Xiamen, 361102, Fujian Province, P.R. China.
| | - Tianhui Hu
- Cancer Research Center, Xiamen University Medical College, Xiamen, 361102, Fujian Province, P.R. China.
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13
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Yuan Q, Ren C, Xu W, Petri B, Zhang J, Zhang Y, Kubes P, Wu D, Tang W. PKN1 Directs Polarized RAB21 Vesicle Trafficking via RPH3A and Is Important for Neutrophil Adhesion and Ischemia-Reperfusion Injury. Cell Rep 2017; 19:2586-2597. [PMID: 28636945 PMCID: PMC5548392 DOI: 10.1016/j.celrep.2017.05.080] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 04/18/2017] [Accepted: 05/24/2017] [Indexed: 01/08/2023] Open
Abstract
Polarized vesicle transport plays an important role in cell polarization, but the mechanisms underlying this process and its role in innate immune responses are not well understood. Here, we describe a phosphorylation-regulated polarization mechanism that is important for neutrophil adhesion to endothelial cells during inflammatory responses. We show that the protein kinase PKN1 phosphorylates RPH3A, which enhances binding of RPH3A to guanosine triphosphate (GTP)-bound RAB21. These interactions are important for polarized localization of RAB21 and RPH3A in neutrophils, which leads to PIP5K1C90 polarization. Consistent with the roles of PIP5K1C90 polarization, the lack of PKN1 or RPH3A impairs neutrophil integrin activation, adhesion to endothelial cells, and infiltration in inflammatory models. Furthermore, myeloid-specific loss of PKN1 decreases tissue injury in a renal ischemia-reperfusion model. Thus, this study characterizes a mechanism for protein polarization in neutrophils and identifies a potential protein kinase target for therapeutic intervention in reperfusion-related tissue injury.
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Affiliation(s)
- Qianying Yuan
- Department of Pharmacology, Vascular Biology and Therapeutic Program, Yale School of Medicine, New Haven, CT 06520, USA
| | - Chunguang Ren
- Department of Pharmacology, Vascular Biology and Therapeutic Program, Yale School of Medicine, New Haven, CT 06520, USA
| | - Wenwen Xu
- Department of Pharmacology, Vascular Biology and Therapeutic Program, Yale School of Medicine, New Haven, CT 06520, USA
| | - Björn Petri
- Snyder Institute for Chronic Diseases Mouse Phenomics Resource Laboratory, University of Calgary, Calgary, AB T2N 4N1, Canada; Department of Microbiology, Immunology and Infectious Diseases, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Jiasheng Zhang
- Department of Internal Medicine, Yale School of Medicine, New Haven, CT 06520, USA
| | - Yong Zhang
- Department of Pharmacology, Vascular Biology and Therapeutic Program, Yale School of Medicine, New Haven, CT 06520, USA
| | - Paul Kubes
- Snyder Institute for Chronic Diseases Mouse Phenomics Resource Laboratory, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Dianqing Wu
- Department of Pharmacology, Vascular Biology and Therapeutic Program, Yale School of Medicine, New Haven, CT 06520, USA.
| | - Wenwen Tang
- Department of Pharmacology, Vascular Biology and Therapeutic Program, Yale School of Medicine, New Haven, CT 06520, USA.
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14
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The Type IV Secretion System Effector Protein CirA Stimulates the GTPase Activity of RhoA and Is Required for Virulence in a Mouse Model of Coxiella burnetii Infection. Infect Immun 2016; 84:2524-33. [PMID: 27324482 DOI: 10.1128/iai.01554-15] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 06/14/2016] [Indexed: 01/08/2023] Open
Abstract
Coxiella burnetii, the etiological agent of Q fever in humans, is an intracellular pathogen that replicates in an acidified parasitophorous vacuole derived from host lysosomes. Generation of this replicative compartment requires effectors delivered into the host cell by the Dot/Icm type IVb secretion system. Several effectors crucial for C. burnetii intracellular replication have been identified, but the host pathways coopted by these essential effectors are poorly defined, and very little is known about how spacious vacuoles are formed and maintained. Here we demonstrate that the essential type IVb effector, CirA, stimulates GTPase activity of RhoA. Overexpression of CirA in mammalian cells results in cell rounding and stress fiber disruption, a phenotype that is rescued by overexpression of wild-type or constitutively active RhoA. Unlike other effector proteins that subvert Rho GTPases to modulate uptake, CirA is the first effector identified that is dispensable for uptake and instead recruits Rho GTPase to promote biogenesis of the bacterial vacuole. Collectively our results highlight the importance of CirA in coopting host Rho GTPases for establishment of Coxiella burnetii infection and virulence in mammalian cell culture and mouse models of infection.
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15
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Spang A. Membrane Tethering Complexes in the Endosomal System. Front Cell Dev Biol 2016; 4:35. [PMID: 27243003 PMCID: PMC4860415 DOI: 10.3389/fcell.2016.00035] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 04/18/2016] [Indexed: 01/08/2023] Open
Abstract
Vesicles that are generated by endocytic events at the plasma membrane are destined to early endosomes. A prerequisite for proper fusion is the tethering of two membrane entities. Tethering of vesicles to early endosomes is mediated by the class C core vacuole/endosome tethering (CORVET) complex, while fusion of late endosomes with lysosomes depends on the homotypic fusion and vacuole protein sorting (HOPS) complex. Recycling through the trans-Golgi network (TGN) and to the plasma membrane is facilitated by the Golgi associated retrograde protein (GARP) and endosome-associated recycling protein (EARP) complexes, respectively. However, there are other tethering functions in the endosomal system as there are multiple pathways through which proteins can be delivered from endosomes to either the TGN or the plasma membrane. Furthermore, proteins that may be part of novel tethering complexes have been recently identified. Thus, it is likely that more tethering factors exist. In this review, I will provide an overview of different tethering complexes of the endosomal system and discuss how they may provide specificity in membrane traffic.
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Affiliation(s)
- Anne Spang
- Biozentrum, Growth & Development, University of Basel Basel, Switzerland
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16
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Martin-Urdiroz M, Deeks MJ, Horton CG, Dawe HR, Jourdain I. The Exocyst Complex in Health and Disease. Front Cell Dev Biol 2016; 4:24. [PMID: 27148529 PMCID: PMC4828438 DOI: 10.3389/fcell.2016.00024] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Accepted: 03/11/2016] [Indexed: 01/23/2023] Open
Abstract
Exocytosis involves the fusion of intracellular secretory vesicles with the plasma membrane, thereby delivering integral membrane proteins to the cell surface and releasing material into the extracellular space. Importantly, exocytosis also provides a source of lipid moieties for membrane extension. The tethering of the secretory vesicle before docking and fusion with the plasma membrane is mediated by the exocyst complex, an evolutionary conserved octameric complex of proteins. Recent findings indicate that the exocyst complex also takes part in other intra-cellular processes besides secretion. These various functions seem to converge toward defining a direction of membrane growth in a range of systems from fungi to plants and from neurons to cilia. In this review we summarize the current knowledge of exocyst function in cell polarity, signaling and cell-cell communication and discuss implications for plant and animal health and disease.
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Affiliation(s)
| | - Michael J Deeks
- Biosciences, College of Life and Environmental Sciences, University of Exeter Exeter, UK
| | - Connor G Horton
- Biosciences, College of Life and Environmental Sciences, University of Exeter Exeter, UK
| | - Helen R Dawe
- Biosciences, College of Life and Environmental Sciences, University of Exeter Exeter, UK
| | - Isabelle Jourdain
- Biosciences, College of Life and Environmental Sciences, University of Exeter Exeter, UK
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17
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Flavone inhibits migration through DLC1/RhoA pathway by decreasing ROS generation in breast cancer cells. In Vitro Cell Dev Biol Anim 2016; 52:589-97. [DOI: 10.1007/s11626-016-0010-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 02/11/2016] [Indexed: 12/14/2022]
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18
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Abstract
The oculocerebrorenal syndrome of Lowe is a rare X-linked multisystemic disorder characterized by the triad of congenital cataracts, intellectual disability, and proximal renal tubular dysfunction. Whereas the ocular manifestations and severe muscular hypotonia are the typical first diagnostic clues apparent at birth, the manifestations of incomplete renal Fanconi syndrome are often recognized only later in life. Other characteristic features are progressive severe growth retardation and behavioral problems, with tantrums. Many patients develop a debilitating arthropathy. Treatment is symptomatic, and the life span rarely exceeds 40 years. The causative oculocerebrorenal syndrome of Lowe gene (OCRL) encodes the inositol polyphosphate 5-phosphatase OCRL-1. OCRL variants have not only been found in classic Lowe syndrome, but also in patients with a predominantly renal phenotype classified as Dent disease type 2 (Dent-2). Recent data indicate that there is a phenotypic continuum between Dent-2 disease and Lowe syndrome, suggesting that there are individual differences in the ability to compensate for the loss of enzyme function. Extensive research has demonstrated that OCRL-1 is involved in multiple intracellular processes involving endocytic trafficking and actin skeleton dynamics. This explains the multi-organ manifestations of the disease. Still, the mechanisms underlying the wide phenotypic spectrum are poorly understood, and we are far from a causative therapy. In this review, we provide an update on clinical and molecular genetic findings in Lowe syndrome and the cellular and physiological functions of OCRL-1.
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19
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Safavian D, Zayed Y, Indriolo E, Chapman L, Ahmed A, Goring DR. RNA Silencing of Exocyst Genes in the Stigma Impairs the Acceptance of Compatible Pollen in Arabidopsis. PLANT PHYSIOLOGY 2015; 169:2526-38. [PMID: 26443677 PMCID: PMC4677879 DOI: 10.1104/pp.15.00635] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 10/06/2015] [Indexed: 05/19/2023]
Abstract
Initial pollen-pistil interactions in the Brassicaceae are regulated by rapid communication between pollen grains and stigmatic papillae and are fundamentally important, as they are the first step toward successful fertilization. The goal of this study was to examine the requirement of exocyst subunits, which function in docking secretory vesicles to sites of polarized secretion, in the context of pollen-pistil interactions. One of the exocyst subunit genes, EXO70A1, was previously identified as an essential factor in the stigma for the acceptance of compatible pollen in Arabidopsis (Arabidopsis thaliana) and Brassica napus. We hypothesized that EXO70A1, along with other exocyst subunits, functions in the Brassicaceae dry stigma to deliver cargo-bearing secretory vesicles to the stigmatic papillar plasma membrane, under the pollen attachment site, for pollen hydration and pollen tube entry. Here, we investigated the functions of exocyst complex genes encoding the remaining seven subunits, SECRETORY3 (SEC3), SEC5, SEC6, SEC8, SEC10, SEC15, and EXO84, in Arabidopsis stigmas following compatible pollinations. Stigma-specific RNA-silencing constructs were used to suppress the expression of each exocyst subunit individually. The early postpollination stages of pollen grain adhesion, pollen hydration, pollen tube penetration, seed set, and overall fertility were analyzed in the transgenic lines to evaluate the requirement of each exocyst subunit. Our findings provide comprehensive evidence that all eight exocyst subunits are necessary in the stigma for the acceptance of compatible pollen. Thus, this work implicates a fully functional exocyst complex as a component of the compatible pollen response pathway to promote pollen acceptance.
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Affiliation(s)
- Darya Safavian
- Department of Cell and Systems Biology and Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, Ontario, Canada M5S 3B2
| | - Yara Zayed
- Department of Cell and Systems Biology and Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, Ontario, Canada M5S 3B2
| | - Emily Indriolo
- Department of Cell and Systems Biology and Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, Ontario, Canada M5S 3B2
| | - Laura Chapman
- Department of Cell and Systems Biology and Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, Ontario, Canada M5S 3B2
| | - Abdalla Ahmed
- Department of Cell and Systems Biology and Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, Ontario, Canada M5S 3B2
| | - Daphne R Goring
- Department of Cell and Systems Biology and Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, Ontario, Canada M5S 3B2
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20
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Wang N, Wang M, Zhu YH, Grosel TW, Sun D, Kudryashov DS, Wu JQ. The Rho-GEF Gef3 interacts with the septin complex and activates the GTPase Rho4 during fission yeast cytokinesis. Mol Biol Cell 2014; 26:238-55. [PMID: 25411334 PMCID: PMC4294672 DOI: 10.1091/mbc.e14-07-1196] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Rho GTPases, activated by Rho guanine nucleotide exchange factors (GEFs), are conserved molecular switches for signal transductions that regulate diverse cellular processes, including cell polarization and cytokinesis. The fission yeast Schizosaccharomyces pombe has six Rho GTPases (Cdc42 and Rho1-Rho5) and seven Rho GEFs (Scd1, Rgf1-Rgf3, and Gef1-Gef3). The GEFs for Rho2-Rho5 have not been unequivocally assigned. In particular, Gef3, the smallest Rho GEF, was barely studied. Here we show that Gef3 colocalizes with septins at the cell equator. Gef3 physically interacts with septins and anillin Mid2 and depends on them to localize. Gef3 coprecipitates with GDP-bound Rho4 in vitro and accelerates nucleotide exchange of Rho4, suggesting that Gef3 is a GEF for Rho4. Consistently, Gef3 and Rho4 are in the same genetic pathways to regulate septum formation and/or cell separation. In gef3∆ cells, the localizations of two potential Rho4 effectors--glucanases Eng1 and Agn1--are abnormal, and active Rho4 level is reduced, indicating that Gef3 is involved in Rho4 activation in vivo. Moreover, overexpression of active Rho4 or Eng1 rescues the septation defects of mutants containing gef3∆. Together our data support that Gef3 interacts with the septin complex and activates Rho4 GTPase as a Rho GEF for septation in fission yeast.
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Affiliation(s)
| | - Mo Wang
- Department of Molecular Genetics
| | | | | | | | | | - Jian-Qiu Wu
- Department of Molecular Genetics Department of Molecular and Cellular Biochemistry, The Ohio State University, Columbus, OH 43210
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