1
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Abrams J, Nance J. A polarity pathway for exocyst-dependent intracellular tube extension. eLife 2021; 10:65169. [PMID: 33687331 PMCID: PMC8021397 DOI: 10.7554/elife.65169] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 03/08/2021] [Indexed: 12/25/2022] Open
Abstract
Lumen extension in intracellular tubes can occur when vesicles fuse with an invading apical membrane. Within the Caenorhabditis elegans excretory cell, which forms an intracellular tube, the exocyst vesicle-tethering complex is enriched at the lumenal membrane and is required for its outgrowth, suggesting that exocyst-targeted vesicles extend the lumen. Here, we identify a pathway that promotes intracellular tube extension by enriching the exocyst at the lumenal membrane. We show that PAR-6 and PKC-3/aPKC concentrate at the lumenal membrane and promote lumen extension. Using acute protein depletion, we find that PAR-6 is required for exocyst membrane recruitment, whereas PAR-3, which can recruit the exocyst in mammals, appears dispensable for exocyst localization and lumen extension. Finally, we show that CDC-42 and RhoGEF EXC-5/FGD regulate lumen extension by recruiting PAR-6 and PKC-3 to the lumenal membrane. Our findings reveal a pathway that connects CDC-42, PAR proteins, and the exocyst to extend intracellular tubes.
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Affiliation(s)
- Joshua Abrams
- Skirball Institute of Biomolecular Medicine, NYU Grossman School of Medicine, New York, United States
| | - Jeremy Nance
- Skirball Institute of Biomolecular Medicine, NYU Grossman School of Medicine, New York, United States.,Department of Cell Biology, NYU Grossman School of Medicine, New York, United States
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2
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Abstract
As multi-cellular organisms evolved from small clusters of cells to complex metazoans, biological tubes became essential for life. Tubes are typically thought of as mainly playing a role in transport, with the hollow space (lumen) acting as a conduit to distribute nutrients and waste, or for gas exchange. However, biological tubes also provide a platform for physiological, mechanical, and structural functions. Indeed, tubulogenesis is often a critical aspect of morphogenesis and organogenesis. C. elegans is made up of tubes that provide structural support and protection (the epidermis), perform the mechanical and enzymatic processes of digestion (the buccal cavity, pharynx, intestine, and rectum), transport fluids for osmoregulation (the excretory system), and execute the functions necessary for reproduction (the germline, spermatheca, uterus and vulva). Here we review our current understanding of the genetic regulation, molecular processes, and physical forces involved in tubulogenesis and morphogenesis of the epidermal, digestive and excretory systems in C. elegans.
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Affiliation(s)
- Daniel D Shaye
- Department of Physiology and Biophysics, University of Illinois at Chicago-College of Medicine, Chicago, IL, United States.
| | - Martha C Soto
- Department of Pathology and Laboratory Medicine, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ, United States.
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3
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Yang Z, Mattingly BC, Hall DH, Ackley BD, Buechner M. Terminal web and vesicle trafficking proteins mediate nematode single-cell tubulogenesis. J Cell Biol 2020; 219:e202003152. [PMID: 32860501 PMCID: PMC7594493 DOI: 10.1083/jcb.202003152] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 06/15/2020] [Accepted: 08/03/2020] [Indexed: 11/22/2022] Open
Abstract
Single-celled tubules represent a complicated structure that forms during development, requiring extension of a narrow cytoplasm surrounding a lumen exerting osmotic pressure that can burst the luminal membrane. Genetic studies on the excretory canal cell of Caenorhabditis elegans have revealed many proteins that regulate the cytoskeleton, vesicular transport, and physiology of the narrow canals. Here, we show that βH-spectrin regulates the placement of intermediate filament proteins forming a terminal web around the lumen, and that the terminal web in turn retains a highly conserved protein (EXC-9/CRIP1) that regulates apical endosomal trafficking. EXC-1/IRG, the binding partner of EXC-9, is also localized to the apical membrane and affects apical actin placement and RAB-8-mediated vesicular transport. The results suggest that an intermediate filament protein acts in a novel pathway to direct the traffic of vesicles to locations of lengthening apical surface during single-celled tubule development.
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Affiliation(s)
- Zhe Yang
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS
| | | | - David H. Hall
- Center for C. elegans Anatomy, Albert Einstein College of Medicine, Bronx, NY
| | - Brian D. Ackley
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS
| | - Matthew Buechner
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS
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4
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Buechner M, Yang Z, Al-Hashimi H. A Series of Tubes: The C. elegans Excretory Canal Cell as a Model for Tubule Development. J Dev Biol 2020; 8:jdb8030017. [PMID: 32906663 PMCID: PMC7557474 DOI: 10.3390/jdb8030017] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 08/31/2020] [Accepted: 09/02/2020] [Indexed: 12/25/2022] Open
Abstract
Formation and regulation of properly sized epithelial tubes is essential for multicellular life. The excretory canal cell of C. elegans provides a powerful model for investigating the integration of the cytoskeleton, intracellular transport, and organismal physiology to regulate the developmental processes of tube extension, lumen formation, and lumen diameter regulation in a narrow single cell. Multiple studies have provided new understanding of actin and intermediate filament cytoskeletal elements, vesicle transport, and the role of vacuolar ATPase in determining tube size. Most of the genes discovered have clear homologues in humans, with implications for understanding these processes in mammalian tissues such as Schwann cells, renal tubules, and brain vasculature. The results of several new genetic screens are described that provide a host of new targets for future studies in this informative structure.
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Affiliation(s)
- Matthew Buechner
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045, USA;
- Correspondence:
| | - Zhe Yang
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045, USA;
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5
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Novel exc Genes Involved in Formation of the Tubular Excretory Canals of Caenorhabditis elegans. G3-GENES GENOMES GENETICS 2019; 9:1339-1353. [PMID: 30885922 PMCID: PMC6505153 DOI: 10.1534/g3.119.200626] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Regulation of luminal diameter is critical to the function of small single-celled tubes, of which the seamless tubular excretory canals of Caenorhabditis elegans provide a tractable genetic model. Mutations in several sets of genes exhibit the Exc phenotype, in which canal luminal growth is visibly altered. Here, a focused reverse genomic screen of genes highly expressed in the canals found 18 genes that significantly affect luminal outgrowth or diameter. These genes encode novel proteins as well as highly conserved proteins involved in processes including gene expression, cytoskeletal regulation, and vesicular and transmembrane transport. In addition, two genes act as suppressors on a pathway of conserved genes whose products mediate vesicle movement from early to recycling endosomes. The results provide new tools for understanding the integration of cytoplasmic structure and physiology in forming and maintaining the narrow diameter of single-cell tubules.
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6
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Praslicka B, Harmson JS, Kim J, Rangaraj VR, Ooi A, Gissendanner CR. BINDING SITE ANALYSIS OF THE CAENORHABDITIS ELEGANS NR4A NUCLEAR RECEPTOR NHR-6 DURING DEVELOPMENT. NUCLEAR RECEPTOR RESEARCH 2017; 4. [PMID: 29026837 DOI: 10.11131/2017/101288] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Members of the NR4A subfamily of nuclear receptors make up a highly conserved, functionally diverse group of transcription factors implicated in a multitude of cellular processes such as proliferation, differentiation, apoptosis, metabolism and DNA repair. The gene nhr-6, which encodes the sole C. elegans NR4A nuclear receptor homolog, has a critical role in organogenesis and regulates the development of the spermatheca organ system. Our previous work revealed that nhr-6 is required for spermatheca cell divisions in late L3 and early L4 and spermatheca cell differentiation during the mid L4 stage. Here, we utilized chromatin immunoprecipitation followed by next-generation sequencing (ChIP-seq) to identify NHR-6 binding sites during both the late L3/early L4 and mid L4 developmental stages. Our results revealed 30,745 enriched binding sites for NHR-6, ~70% of which were within 3 kb upstream of a gene transcription start site. Binding sites for a cohort of candidate target genes with probable functions in spermatheca organogenesis were validated through qPCR. Reproductive and spermatheca phenotypes were also evaluated for these genes following a loss-of-function RNAi screen which revealed several genes with critical functions during spermatheca organogenesis. Our results uncovered a complex nuclear receptor regulatory network whereby NHR-6 regulates multiple cellular processes during spermatheca organogenesis.
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Affiliation(s)
- Brandon Praslicka
- Department of Basic Pharmaceutical Sciences, School of Pharmacy, and Biology Program, School of Science, University of Louisiana Monroe, Monroe, LA, USA 71209
| | - Jeremy S Harmson
- Department of Basic Pharmaceutical Sciences, School of Pharmacy, and Biology Program, School of Science, University of Louisiana Monroe, Monroe, LA, USA 71209
| | - Joohyun Kim
- Center for Computation and Technology, Louisiana State University, Baton Rouge, LA, USA 70803
| | - Vittobai Rashika Rangaraj
- Department of Basic Pharmaceutical Sciences, School of Pharmacy, and Biology Program, School of Science, University of Louisiana Monroe, Monroe, LA, USA 71209
| | - Aikseng Ooi
- Department of Pharmacology & Toxicology, College of Pharmacy, University of Arizona, Tucson, AZ, USA 85721
| | - Chris R Gissendanner
- Department of Basic Pharmaceutical Sciences, School of Pharmacy, and Biology Program, School of Science, University of Louisiana Monroe, Monroe, LA, USA 71209
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7
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The Caenorhabditis elegans Excretory System: A Model for Tubulogenesis, Cell Fate Specification, and Plasticity. Genetics 2017; 203:35-63. [PMID: 27183565 DOI: 10.1534/genetics.116.189357] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 03/07/2016] [Indexed: 12/12/2022] Open
Abstract
The excretory system of the nematode Caenorhabditis elegans is a superb model of tubular organogenesis involving a minimum of cells. The system consists of just three unicellular tubes (canal, duct, and pore), a secretory gland, and two associated neurons. Just as in more complex organs, cells of the excretory system must first adopt specific identities and then coordinate diverse processes to form tubes of appropriate topology, shape, connectivity, and physiological function. The unicellular topology of excretory tubes, their varied and sometimes complex shapes, and the dynamic reprogramming of cell identity and remodeling of tube connectivity that occur during larval development are particularly fascinating features of this organ. The physiological roles of the excretory system in osmoregulation and other aspects of the animal's life cycle are only beginning to be explored. The cellular mechanisms and molecular pathways used to build and shape excretory tubes appear similar to those used in both unicellular and multicellular tubes in more complex organs, such as the vertebrate vascular system and kidney, making this simple organ system a useful model for understanding disease processes.
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8
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Shaye DD, Greenwald I. A network of conserved formins, regulated by the guanine exchange factor EXC-5 and the GTPase CDC-42, modulates tubulogenesis in vivo. Development 2016; 143:4173-4181. [PMID: 27697907 DOI: 10.1242/dev.141861] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 09/20/2016] [Indexed: 12/20/2022]
Abstract
The C. elegans excretory cell (EC) is a powerful model for tubulogenesis, a conserved process that requires precise cytoskeletal regulation. EXC-6, an ortholog of the disease-associated formin INF2, coordinates cell outgrowth and lumen formation during EC tubulogenesis by regulating F-actin at the tip of the growing canal and the dynamics of basolateral microtubules. EXC-6 functions in parallel with EXC-5/FGD, a predicted activator of the Rho GTPase Cdc42. Here, we identify the parallel pathway: EXC-5 functions through CDC-42 to regulate two other formins: INFT-2, another INF2 ortholog, and CYK-1, the sole ortholog of the mammalian diaphanous (mDia) family of formins. We show that INFT-2 promotes F-actin accumulation in the EC, and that CYK-1 inhibits INFT-2 to regulate F-actin levels and EXC-6-promoted outgrowth. As INF2 and mDia physically interact and cross-regulate in cultured cells, our work indicates that a conserved EXC-5-CDC-42 pathway modulates this regulatory interaction and that it is functionally important in vivo during tubulogenesis.
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Affiliation(s)
- Daniel D Shaye
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA .,Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA.,Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Iva Greenwald
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA.,Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
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9
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Grussendorf KA, Trezza CJ, Salem AT, Al-Hashimi H, Mattingly BC, Kampmeyer DE, Khan LA, Hall DH, Göbel V, Ackley BD, Buechner M. Facilitation of Endosomal Recycling by an IRG Protein Homolog Maintains Apical Tubule Structure in Caenorhabditis elegans. Genetics 2016; 203:1789-806. [PMID: 27334269 PMCID: PMC4981278 DOI: 10.1534/genetics.116.192559] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2016] [Accepted: 06/15/2016] [Indexed: 02/08/2023] Open
Abstract
Determination of luminal diameter is critical to the function of small single-celled tubes. A series of EXC proteins, including EXC-1, prevent swelling of the tubular excretory canals in Caenorhabditis elegans In this study, cloning of exc-1 reveals it to encode a homolog of mammalian IRG proteins, which play roles in immune response and autophagy and are associated with Crohn's disease. Mutants in exc-1 accumulate early endosomes, lack recycling endosomes, and exhibit abnormal apical cytoskeletal structure in regions of enlarged tubules. EXC-1 interacts genetically with two other EXC proteins that also affect endosomal trafficking. In yeast two-hybrid assays, wild-type and putative constitutively active EXC-1 binds to the LIM-domain protein EXC-9, whose homolog, cysteine-rich intestinal protein, is enriched in mammalian intestine. These results suggest a model for IRG function in forming and maintaining apical tubule structure via regulation of endosomal recycling.
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Affiliation(s)
- Kelly A Grussendorf
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045 Department of Biological Sciences, Minnesota State University, Mankato, Minnesota 56001
| | - Christopher J Trezza
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045
| | - Alexander T Salem
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045
| | - Hikmat Al-Hashimi
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045
| | - Brendan C Mattingly
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045
| | - Drew E Kampmeyer
- Department of Biological Sciences, Minnesota State University, Mankato, Minnesota 56001
| | - Liakot A Khan
- Mucosal Immunology and Biology Research Center, Developmental Biology and Genetics Core, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114
| | - David H Hall
- Department of Neuroscience, Center for Caenorhabditis elegans Anatomy, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Verena Göbel
- Mucosal Immunology and Biology Research Center, Developmental Biology and Genetics Core, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114
| | - Brian D Ackley
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045
| | - Matthew Buechner
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045
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10
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Quintin S, Gally C, Labouesse M. Noncentrosomal microtubules in C. elegans epithelia. Genesis 2016; 54:229-42. [PMID: 26789944 DOI: 10.1002/dvg.22921] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Revised: 01/12/2016] [Accepted: 01/14/2016] [Indexed: 11/12/2022]
Abstract
The microtubule cytoskeleton has a dual contribution to cell organization. First, microtubules help displace chromosomes and provide tracks for organelle transport. Second, microtubule rigidity confers specific mechanical properties to cells, which are crucial in cilia or mechanosensory structures. Here we review the recently uncovered organization and functions of noncentrosomal microtubules in C. elegans epithelia, focusing on how they contribute to nuclear positioning and protein transport. In addition, we describe recent data illustrating how the microtubule and actin cytoskeletons interact to achieve those functions.
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Affiliation(s)
- Sophie Quintin
- Development and Stem Cells Department, IGBMC - CNRS UMR 7104/INSERM U964/Université de Strasbourg, 1 Rue Laurent Fries, Illkirch, 67400, France
| | - Christelle Gally
- Development and Stem Cells Department, IGBMC - CNRS UMR 7104/INSERM U964/Université de Strasbourg, 1 Rue Laurent Fries, Illkirch, 67400, France
| | - Michel Labouesse
- Université Pierre Et Marie Curie, IBPS, CNRS UMR7622, 7 Quai St-Bernard, Paris, 75005, France
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11
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Shaye DD, Greenwald I. The disease-associated formin INF2/EXC-6 organizes lumen and cell outgrowth during tubulogenesis by regulating F-actin and microtubule cytoskeletons. Dev Cell 2015; 32:743-55. [PMID: 25771894 DOI: 10.1016/j.devcel.2015.01.009] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 12/02/2014] [Accepted: 01/13/2015] [Indexed: 10/23/2022]
Abstract
We investigate how outgrowth at the basolateral cell membrane is coordinated with apical lumen formation in the development of a biological tube by characterizing exc-6, a gene required for C. elegans excretory cell (EC) tubulogenesis. We show that EXC-6 is orthologous to the human formin INF2, which polymerizes filamentous actin (F-actin) and binds microtubules (MTs) in vitro. Dominant INF2 mutations cause focal segmental glomerulosclerosis (FSGS), a kidney disease, and FSGS+Charcot-Marie-Tooth neuropathy. We show that activated INF2 can substitute for EXC-6 in C. elegans and that disease-associated mutations cause constitutive activity. Using genetic analysis and live imaging, we show that exc-6 regulates MT and F-actin accumulation at EC tips and dynamics of basolateral-localized MTs, indicating that EXC-6 organizes F-actin and MT cytoskeletons during tubulogenesis. The pathology associated with INF2 mutations is believed to reflect misregulation of F-actin, but our results suggest alternative or additional mechanisms via effects on MT dynamics.
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Affiliation(s)
- Daniel D Shaye
- Howard Hughes Medical Institute, Columbia University, College of Physicians and Surgeons, New York, NY 10032, USA.
| | - Iva Greenwald
- Howard Hughes Medical Institute, Columbia University, College of Physicians and Surgeons, New York, NY 10032, USA; Department of Biochemistry and Molecular Biophysics, Columbia University, College of Physicians and Surgeons, New York, NY 10032, USA; Department of Genetics and Development, Columbia University, College of Physicians and Surgeons, New York, NY 10032, USA.
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12
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Jiang L, Phang JM, Yu J, Harrop SJ, Sokolova AV, Duff AP, Wilk KE, Alkhamici H, Breit SN, Valenzuela SM, Brown LJ, Curmi PMG. CLIC proteins, ezrin, radixin, moesin and the coupling of membranes to the actin cytoskeleton: a smoking gun? BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1838:643-57. [PMID: 23732235 DOI: 10.1016/j.bbamem.2013.05.025] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Revised: 05/20/2013] [Accepted: 05/21/2013] [Indexed: 12/20/2022]
Abstract
The CLIC proteins are a highly conserved family of metazoan proteins with the unusual ability to adopt both soluble and integral membrane forms. The physiological functions of CLIC proteins may include enzymatic activity in the soluble form and anion channel activity in the integral membrane form. CLIC proteins are associated with the ERM proteins: ezrin, radixin and moesin. ERM proteins act as cross-linkers between membranes and the cortical actin cytoskeleton. Both CLIC and ERM proteins are controlled by Rho family small GTPases. CLIC proteins, ERM and Rho GTPases act in a concerted manner to control active membrane processes including the maintenance of microvillar structures, phagocytosis and vesicle trafficking. All of these processes involve the interaction of membranes with the underlying cortical actin cytoskeleton. The relationships between Rho GTPases, CLIC proteins, ERM proteins and the membrane:actin cytoskeleton interface are reviewed. Speculative models are proposed involving the formation of localised multi-protein complexes on the membrane surface that assemble via multiple weak interactions. This article is part of a Special Issue entitled: Reciprocal influences between cell cytoskeleton and membrane channels, receptors and transporters. Guest Editor: Jean Claude Hervé.
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Affiliation(s)
- Lele Jiang
- St Vincent's Centre for Applied Medical Research, St Vincent's Hospital, Sydney, NSW 2010, Australia
| | - Juanita M Phang
- School of Physics, The University of New South Wales, Sydney, NSW 2052, Australia
| | - Jiang Yu
- School of Physics, The University of New South Wales, Sydney, NSW 2052, Australia
| | - Stephen J Harrop
- School of Physics, The University of New South Wales, Sydney, NSW 2052, Australia
| | - Anna V Sokolova
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, Australia
| | - Anthony P Duff
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, Australia
| | - Krystyna E Wilk
- School of Physics, The University of New South Wales, Sydney, NSW 2052, Australia
| | - Heba Alkhamici
- School of Medical and Molecular Biosciences, The University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Samuel N Breit
- St Vincent's Centre for Applied Medical Research, St Vincent's Hospital, Sydney, NSW 2010, Australia
| | - Stella M Valenzuela
- School of Medical and Molecular Biosciences, The University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Louise J Brown
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, NSW 2109, Australia
| | - Paul M G Curmi
- St Vincent's Centre for Applied Medical Research, St Vincent's Hospital, Sydney, NSW 2010, Australia; School of Physics, The University of New South Wales, Sydney, NSW 2052, Australia.
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13
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Kolotuev I, Hyenne V, Schwab Y, Rodriguez D, Labouesse M. A pathway for unicellular tube extension depending on the lymphatic vessel determinant Prox1 and on osmoregulation. Nat Cell Biol 2013; 15:157-68. [DOI: 10.1038/ncb2662] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2012] [Accepted: 11/26/2012] [Indexed: 01/14/2023]
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14
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McShea MA, Schmidt KL, Dubuke ML, Baldiga CE, Sullender ME, Reis AL, Zhang S, O'Toole SM, Jeffers MC, Warden RM, Kenney AH, Gosselin J, Kuhlwein M, Hashmi SK, Stringham EG, Ryder EF. Abelson interactor-1 (ABI-1) interacts with MRL adaptor protein MIG-10 and is required in guided cell migrations and process outgrowth in C. elegans. Dev Biol 2012; 373:1-13. [PMID: 23022657 DOI: 10.1016/j.ydbio.2012.09.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 09/12/2012] [Accepted: 09/21/2012] [Indexed: 11/19/2022]
Abstract
Directed cell migration and process outgrowth are vital to proper development of many metazoan tissues. These processes are dependent on reorganization of the actin cytoskeleton in response to external guidance cues. During development of the nervous system, the MIG-10/RIAM/Lamellipodin (MRL) signaling proteins are thought to transmit positional information from surface guidance cues to the actin polymerization machinery, and thus to promote polarized outgrowth of axons. In C. elegans, mutations in the MRL family member gene mig-10 result in animals that have defects in axon guidance, neuronal migration, and the outgrowth of the processes or 'canals' of the excretory cell, which is required for osmoregulation in the worm. In addition, mig-10 mutant animals have recently been shown to have defects in clustering of vesicles at the synapse. To determine additional molecular partners of MIG-10, we conducted a yeast two-hybrid screen using isoform MIG-10A as bait and isolated Abelson-interactor protein-1 (ABI-1). ABI-1, a downstream target of Abl non-receptor tyrosine kinase, is a member of the WAVE regulatory complex (WRC) involved in the initiation of actin polymerization. Further analysis using a co-immunoprecipitation system confirmed the interaction of MIG-10 and ABI-1 and showed that it requires the SH3 domain of ABI-1. Single mutants for mig-10 and abi-1 displayed similar phenotypes of incomplete migration of the ALM neurons and truncated outgrowth of the excretory cell canals, suggesting that the ABI-1/MIG-10 interaction is relevant in vivo. Cell autonomous expression of MIG-10 isoforms rescued both the neuronal migration and the canal outgrowth defects, showing that MIG-10 functions autonomously in the ALM neurons and the excretory cell. These results suggest that MIG-10 and ABI-1 interact physically to promote cell migration and process outgrowth in vivo. In the excretory canal, ABI-1 is thought to act downstream of UNC-53/NAV2, linking this large scaffolding protein to actin polymerization during excretory canal outgrowth. abi-1(RNAi) enhanced the excretory canal truncation observed in mig-10 mutants, while double mutant analysis between unc-53 and mig-10 showed no increased truncation of the posterior canal beyond that observed in mig-10 mutants. Morphological analysis of mig-10 and unc-53 mutants showed that these genes regulate canal diameter as well as its length, suggesting that defective lumen formation may be linked to the ability of the excretory canal to grow out longitudinally. Taken together, our results suggest that MIG-10, UNC-53, and ABI-1 act sequentially to mediate excretory cell process outgrowth.
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Affiliation(s)
- Molly A McShea
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01609, USA.
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15
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Zou W, Greenblatt MB, Shim JH, Kant S, Zhai B, Lotinun S, Brady N, Hu DZ, Gygi SP, Baron R, Davis RJ, Jones D, Glimcher LH. MLK3 regulates bone development downstream of the faciogenital dysplasia protein FGD1 in mice. J Clin Invest 2011; 121:4383-92. [PMID: 21965325 PMCID: PMC3204846 DOI: 10.1172/jci59041] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Accepted: 08/24/2011] [Indexed: 12/28/2022] Open
Abstract
Mutations in human FYVE, RhoGEF, and PH domain-containing 1 (FGD1) cause faciogenital dysplasia (FGDY; also known as Aarskog syndrome), an X-linked disorder that affects multiple skeletal structures. FGD1 encodes a guanine nucleotide exchange factor (GEF) that specifically activates the Rho GTPase CDC42. However, the mechanisms by which mutations in FGD1 affect skeletal development are unknown. Here, we describe what we believe to be a novel signaling pathway in osteoblasts initiated by FGD1 that involves the MAP3K mixed-lineage kinase 3 (MLK3). We observed that MLK3 functions downstream of FGD1 to regulate ERK and p38 MAPK, which in turn phosphorylate and activate the master regulator of osteoblast differentiation, Runx2. Mutations in FGD1 found in individuals with FGDY ablated its ability to activate MLK3. Consistent with our description of this pathway and the phenotype of patients with FGD1 mutations, mice with a targeted deletion of Mlk3 displayed multiple skeletal defects, including dental abnormalities, deficient calvarial mineralization, and reduced bone mass. Furthermore, mice with knockin of a mutant Mlk3 allele that is resistant to activation by FGD1/CDC42 displayed similar skeletal defects, demonstrating that activation of MLK3 specifically by FGD1/CDC42 is important for skeletal mineralization. Thus, our results provide a putative biochemical mechanism for the skeletal defects in human FGDY and suggest that modulating MAPK signaling may benefit these patients.
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MESH Headings
- Animals
- Bone Development/genetics
- Bone Development/physiology
- Disease Models, Animal
- Dwarfism/genetics
- Dwarfism/pathology
- Dwarfism/physiopathology
- Enzyme Activation
- Face/abnormalities
- Face/pathology
- Face/physiopathology
- Female
- Gene Knock-In Techniques
- Genetic Diseases, X-Linked/genetics
- Genetic Diseases, X-Linked/pathology
- Genetic Diseases, X-Linked/physiopathology
- Genitalia, Male/abnormalities
- Genitalia, Male/pathology
- Genitalia, Male/physiopathology
- Guanine Nucleotide Exchange Factors/genetics
- Guanine Nucleotide Exchange Factors/physiology
- Hand Deformities, Congenital/genetics
- Hand Deformities, Congenital/pathology
- Hand Deformities, Congenital/physiopathology
- Heart Defects, Congenital/genetics
- Heart Defects, Congenital/pathology
- Heart Defects, Congenital/physiopathology
- Humans
- MAP Kinase Kinase Kinases/deficiency
- MAP Kinase Kinase Kinases/genetics
- MAP Kinase Kinase Kinases/physiology
- MAP Kinase Signaling System
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Mutant Strains
- Mutation
- Osteoblasts/pathology
- Osteoblasts/physiology
- Proteins/genetics
- Proteins/physiology
- cdc42 GTP-Binding Protein/metabolism
- p38 Mitogen-Activated Protein Kinases/metabolism
- Mitogen-Activated Protein Kinase Kinase Kinase 11
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Affiliation(s)
- Weiguo Zou
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Department of Medicine, Harvard Medical School, and Ragon Institute of MGH, Harvard and MIT, Boston, Massachusetts, USA.
Howard Hughes Medical Institute and Program in Molecular Medicine, Department of Biochemistry and Molecular Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA.
Department of Oral Medicine Infection and Immunity, Harvard Dental School, Boston, Massachusetts, USA
| | - Matthew B. Greenblatt
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Department of Medicine, Harvard Medical School, and Ragon Institute of MGH, Harvard and MIT, Boston, Massachusetts, USA.
Howard Hughes Medical Institute and Program in Molecular Medicine, Department of Biochemistry and Molecular Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA.
Department of Oral Medicine Infection and Immunity, Harvard Dental School, Boston, Massachusetts, USA
| | - Jae-Hyuck Shim
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Department of Medicine, Harvard Medical School, and Ragon Institute of MGH, Harvard and MIT, Boston, Massachusetts, USA.
Howard Hughes Medical Institute and Program in Molecular Medicine, Department of Biochemistry and Molecular Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA.
Department of Oral Medicine Infection and Immunity, Harvard Dental School, Boston, Massachusetts, USA
| | - Shashi Kant
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Department of Medicine, Harvard Medical School, and Ragon Institute of MGH, Harvard and MIT, Boston, Massachusetts, USA.
Howard Hughes Medical Institute and Program in Molecular Medicine, Department of Biochemistry and Molecular Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA.
Department of Oral Medicine Infection and Immunity, Harvard Dental School, Boston, Massachusetts, USA
| | - Bo Zhai
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Department of Medicine, Harvard Medical School, and Ragon Institute of MGH, Harvard and MIT, Boston, Massachusetts, USA.
Howard Hughes Medical Institute and Program in Molecular Medicine, Department of Biochemistry and Molecular Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA.
Department of Oral Medicine Infection and Immunity, Harvard Dental School, Boston, Massachusetts, USA
| | - Sutada Lotinun
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Department of Medicine, Harvard Medical School, and Ragon Institute of MGH, Harvard and MIT, Boston, Massachusetts, USA.
Howard Hughes Medical Institute and Program in Molecular Medicine, Department of Biochemistry and Molecular Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA.
Department of Oral Medicine Infection and Immunity, Harvard Dental School, Boston, Massachusetts, USA
| | - Nicholas Brady
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Department of Medicine, Harvard Medical School, and Ragon Institute of MGH, Harvard and MIT, Boston, Massachusetts, USA.
Howard Hughes Medical Institute and Program in Molecular Medicine, Department of Biochemistry and Molecular Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA.
Department of Oral Medicine Infection and Immunity, Harvard Dental School, Boston, Massachusetts, USA
| | - Dorothy Zhang Hu
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Department of Medicine, Harvard Medical School, and Ragon Institute of MGH, Harvard and MIT, Boston, Massachusetts, USA.
Howard Hughes Medical Institute and Program in Molecular Medicine, Department of Biochemistry and Molecular Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA.
Department of Oral Medicine Infection and Immunity, Harvard Dental School, Boston, Massachusetts, USA
| | - Steven P. Gygi
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Department of Medicine, Harvard Medical School, and Ragon Institute of MGH, Harvard and MIT, Boston, Massachusetts, USA.
Howard Hughes Medical Institute and Program in Molecular Medicine, Department of Biochemistry and Molecular Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA.
Department of Oral Medicine Infection and Immunity, Harvard Dental School, Boston, Massachusetts, USA
| | - Roland Baron
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Department of Medicine, Harvard Medical School, and Ragon Institute of MGH, Harvard and MIT, Boston, Massachusetts, USA.
Howard Hughes Medical Institute and Program in Molecular Medicine, Department of Biochemistry and Molecular Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA.
Department of Oral Medicine Infection and Immunity, Harvard Dental School, Boston, Massachusetts, USA
| | - Roger J. Davis
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Department of Medicine, Harvard Medical School, and Ragon Institute of MGH, Harvard and MIT, Boston, Massachusetts, USA.
Howard Hughes Medical Institute and Program in Molecular Medicine, Department of Biochemistry and Molecular Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA.
Department of Oral Medicine Infection and Immunity, Harvard Dental School, Boston, Massachusetts, USA
| | - Dallas Jones
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Department of Medicine, Harvard Medical School, and Ragon Institute of MGH, Harvard and MIT, Boston, Massachusetts, USA.
Howard Hughes Medical Institute and Program in Molecular Medicine, Department of Biochemistry and Molecular Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA.
Department of Oral Medicine Infection and Immunity, Harvard Dental School, Boston, Massachusetts, USA
| | - Laurie H. Glimcher
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Department of Medicine, Harvard Medical School, and Ragon Institute of MGH, Harvard and MIT, Boston, Massachusetts, USA.
Howard Hughes Medical Institute and Program in Molecular Medicine, Department of Biochemistry and Molecular Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA.
Department of Oral Medicine Infection and Immunity, Harvard Dental School, Boston, Massachusetts, USA
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16
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Mattingly BC, Buechner M. The FGD homologue EXC-5 regulates apical trafficking in C. elegans tubules. Dev Biol 2011; 359:59-72. [PMID: 21889936 PMCID: PMC3212395 DOI: 10.1016/j.ydbio.2011.08.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2011] [Revised: 07/09/2011] [Accepted: 08/17/2011] [Indexed: 12/30/2022]
Abstract
Maintenance of the shape of biological tubules is critical for development and physiology of metazoan organisms. Loss of function of the Caenorhabditis elegans FGD protein EXC-5 allows large fluid-filled cysts to form in the lumen of the single-cell excretory canal tubules, while overexpression of exc-5 causes defects at the tubule's basolateral surface. We have examined the effects of altering expression levels of exc-5 on the distribution of fluorescently-marked subcellular organelles. In exc-5 mutants, early endosomes build up in the cell, especially in areas close to cysts, while recycling endosomes are depleted. Endosome morphology changes prior to cyst formation. Conversely, when exc-5 is overexpressed, recycling endosomes are enriched. Since FGD proteins activate the small GTPases CDC42 and Rac, these results support the hypothesis that EXC-5 acts through small GTPases to move material from apical early endosomes to recycling endosomes, and that loss of such movement is likely the cause of tubule deformation both in nematodes and in tissues affected by FGD dysfunction such as Charcot-Marie-Tooth Syndrome type 4H.
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Affiliation(s)
- Brendan C Mattingly
- Dept. of Molecular Biosciences, University of Kansas, Lawrence, KS, 66045, USA
| | - Matthew Buechner
- Dept. of Molecular Biosciences, University of Kansas, Lawrence, KS, 66045, USA.
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17
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Seamen E, Blanchette JM, Han M. P-type ATPase TAT-2 negatively regulates monomethyl branched-chain fatty acid mediated function in post-embryonic growth and development in C. elegans. PLoS Genet 2009; 5:e1000589. [PMID: 19662161 PMCID: PMC2716530 DOI: 10.1371/journal.pgen.1000589] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2009] [Accepted: 07/08/2009] [Indexed: 01/01/2023] Open
Abstract
Monomethyl branched-chain fatty acids (mmBCFAs) are essential for Caenorhabditis elegans growth and development. To identify factors acting downstream of mmBCFAs for their function in growth regulation, we conducted a genetic screen for suppressors of the L1 arrest that occurs in animals depleted of the 17-carbon mmBCFA C17ISO. Three of the suppressor mutations defined an unexpected player, the P-type ATPase TAT-2, which belongs to the flippase family of proteins that are implicated in mediating phospholipid bilayer asymmetry. We provide evidence that TAT-2, but not other TAT genes, has a specific role in antagonizing the regulatory activity of mmBCFAs in intestinal cells. Interestingly, we found that mutations in tat-2 also suppress the lethality caused by inhibition of the first step in sphingolipid biosynthesis. We further showed that the fatty acid side-chains of glycosylceramides contain 20%–30% mmBCFAs and that this fraction is greatly diminished in the absence of mmBCFA biosynthesis. These results suggest a model in which a C17ISO-containing sphingolipid may mediate the regulatory functions of mmBCFAs and is negatively regulated by TAT-2 in intestinal cells. This work indicates a novel connection between a P-type ATPase and the critical regulatory function of a specific fatty acid. Fatty acids serve diverse functions in organisms, including roles at the cell membrane to coordinate cell signaling processes. Monomethyl branched-chain fatty acids (mmBCFAs) are a special type of fatty acid that is commonly present in animals. Because mmBCFAs are a small component of the total fatty acid pool, their functions have not been a major research focus and are largely unclear. We tackled the problem using the nematode C. elegans. Our laboratory previously found that without mmBCFAs, worms cannot develop normally and die. To understand how these obscure fatty acids perform such important roles, we searched for other factors involved in the process by conducting a mutagenesis screen to uncover mutant worms that can recover the ability to grow without the presence of mmBCFAs. We found several such mutations in a single gene that codes for a protein called TAT-2. TAT-2 is one of several poorly understood P-type ATPases that likely help maintain the proper lipid structure in cell membranes. Our work indicates that TAT-2 antagonizes the growth regulatory function of mmBCFAs in intestinal cells. Studies on how mmBCFAs and this protein functionally interact explore a novel, interesting, and important problem that is only beginning to be understood.
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Affiliation(s)
- Emylie Seamen
- Howard Hughes Medical Institute, University of Colorado at Boulder, Boulder, Colorado, United States of America
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado at Boulder, Boulder, Colorado, United States of America
| | - Jennifer M. Blanchette
- Howard Hughes Medical Institute, University of Colorado at Boulder, Boulder, Colorado, United States of America
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado at Boulder, Boulder, Colorado, United States of America
| | - Min Han
- Howard Hughes Medical Institute, University of Colorado at Boulder, Boulder, Colorado, United States of America
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado at Boulder, Boulder, Colorado, United States of America
- * E-mail:
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18
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Baer MM, Chanut-Delalande H, Affolter M. Cellular and molecular mechanisms underlying the formation of biological tubes. Curr Top Dev Biol 2009; 89:137-62. [PMID: 19737645 DOI: 10.1016/s0070-2153(09)89006-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Biological tubes are integral components of many organs. Based on their cellular organization, tubes can be divided into three types: multicellular, unicellular, and intracellular. The mechanisms by which these tubes form during development vary significantly, in many cases even for those sharing a similar final architecture. Here, we present recent advances in studying cellular and molecular aspects of tubulogenesis in different organisms.
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Affiliation(s)
- Magdalena M Baer
- Biozentrum der Universität Basel, Klingelbergstrasse, Basel, Switzerland
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19
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Role of the molybdoflavoenzyme aldehyde oxidase homolog 2 in the biosynthesis of retinoic acid: generation and characterization of a knockout mouse. Mol Cell Biol 2008; 29:357-77. [PMID: 18981221 DOI: 10.1128/mcb.01385-08] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The mouse aldehyde oxidase AOH2 (aldehyde oxidase homolog 2) is a molybdoflavoenzyme. Harderian glands are the richest source of AOH2, although the protein is detectable also in sebaceous glands, epidermis, and other keratinized epithelia. The levels of AOH2 in the Harderian gland and skin are controlled by genetic background, being maximal in CD1 and C57BL/6 and minimal in DBA/2, CBA, and 129/Sv strains. Testosterone is a negative regulator of AOH2 in Harderian glands. Purified AOH2 oxidizes retinaldehyde into retinoic acid, while it is devoid of pyridoxal-oxidizing activity. Aoh2(-/-) mice, the first aldehyde oxidase knockout animals ever generated, are viable and fertile. The data obtained for this knockout model indicate a significant role of AOH2 in the local synthesis and biodisposition of endogenous retinoids in the Harderian gland and skin. The Harderian gland's transcriptome of knockout mice demonstrates overall downregulation of direct retinoid-dependent genes as well as perturbations in pathways controlling lipid homeostasis and cellular secretion, particularly in sexually immature animals. The skin of knockout mice is characterized by thickening of the epidermis in basal conditions and after UV light exposure. This has correlates in the corresponding transcriptome, which shows enrichment and overall upregulation of genes involved in hypertrophic responses.
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20
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CRIP homologues maintain apical cytoskeleton to regulate tubule size in C. elegans. Dev Biol 2008; 317:225-33. [PMID: 18384766 DOI: 10.1016/j.ydbio.2008.02.040] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2008] [Accepted: 02/11/2008] [Indexed: 11/22/2022]
Abstract
Maintenance of the shape and diameter of biological tubules is a critical task in the development and physiology of all metazoan organisms. We have cloned the exc-9 gene of Caenorhabditis elegans, which regulates the diameter of the single-cell excretory canal tubules. exc-9 encodes a homologue of the highly expressed mammalian intestinal LIM-domain protein CRIP, whose function has not previously been determined. A second well-conserved CRIP homologue functions in multiple valves of C. elegans. EXC-9 shows genetic interactions with other EXC proteins, including the EXC-5 guanine exchange factor that regulates CDC-42 activity. EXC-9 and its nematode homologue act in polarized epithelial cells that must maintain great flexibility at their apical surface; our results suggest that CRIPs function to maintain cytoskeletal flexibility at the apical surface.
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21
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Diluna ML, Amankulor NM, Johnson MH, Gunel M. Cerebrovascular disease associated with Aarskog-Scott syndrome. Neuroradiology 2007; 49:457-61. [PMID: 17294235 DOI: 10.1007/s00234-007-0209-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2006] [Accepted: 01/05/2007] [Indexed: 11/26/2022]
Abstract
Faciogenital dysplasia, also known as Aarskog-Scott syndrome (AAS), is an X-linked dominant congenital disorder characterized by multiple facial, musculoskeletal, dental, neurological and urogenital abnormalities, ocular manifestations, congenital heart defects, low IQ and behavioral problems. Here we describe an unusual presentation of dysplastic carotid artery, basilar artery malformation or occlusion and posterior circulation aneurysm in a 13-year-old male with AAS.
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Affiliation(s)
- Michael L Diluna
- Department of Neurosurgery, Yale University School of Medicine, 333 Cedar St., Tompkins 4, New Haven, CT 06510, USA.
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22
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Orrico A, Galli L, Cavaliere ML, Garavelli L, Fryns JP, Crushell E, Rinaldi MM, Medeira A, Sorrentino V. Phenotypic and molecular characterisation of the Aarskog–Scott syndrome: a survey of the clinical variability in light of FGD1 mutation analysis in 46 patients. Eur J Hum Genet 2003; 12:16-23. [PMID: 14560308 DOI: 10.1038/sj.ejhg.5201081] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Faciogenital dysplasia or Aarskog-Scott syndrome (AAS) is a genetically heterogeneous developmental disorder. The X-linked form of AAS has been ascribed to mutations in the FGD1 gene. However, although AAS may be considered as a relatively frequent clinical diagnosis, mutations have been established in few patients. Genetic heterogeneity and the clinical overlap with a number of other syndromes might explain this discrepancy. In this study, we have conducted a single-strand conformation polymorphism (SSCP) analysis of the entire coding region of FGD1 in 46 AAS patients and identified eight novel mutations, including one insertion, four deletions and three missense mutations (19.56% detection rate). One mutation (528insC) was found in two independent families. The mutations are scattered all along the coding sequence. Phenotypically, all affected males present with the characteristic AAS phenotype. FGD1 mutations were not associated with severe mental retardation. However, neuropsychiatric disorders, mainly behavioural and learning problems in childhood, were observed in five out of 12 mutated individuals. The current study provides further evidence that mutations of FGD1 may cause AAS and expands the spectrum of disease-causing mutations. The importance of considering the neuropsychological phenotype of AAS patients is discussed.
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Affiliation(s)
- Alfredo Orrico
- Molecular Medicine, Azienda Ospedaliera Universitaria Senese, Siena, Italy.
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23
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Fujita M, Hawkinson D, King KV, Hall DH, Sakamoto H, Buechner M. The role of the ELAV homologue EXC-7 in the development of the Caenorhabditis elegans excretory canals. Dev Biol 2003; 256:290-301. [PMID: 12679103 DOI: 10.1016/s0012-1606(03)00040-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The exc mutations of Caenorhabditis elegans alter the position and shape of the apical cytoskeleton in polarized epithelial cells. Mutants in exc-7 form small cysts throughout the tubular excretory canals that regulate organismal osmolarity. We have cloned the exc-7 gene, the closest nematode homologue to the neural RNA-binding protein ELAV. EXC-7 is expressed in the canal for a short time midway through embryogenesis. Cysts in exc-7 mutants do not develop until several hours later, beginning at the time of hatching. We find that the first larval period is when the canal completes the majority of its outgrowth, and adds new apical cytoskeleton at a rapid rate. Ultrastructural studies show that exc-7 mutant defects resemble loss of beta(H)-spectrin (encoded by sma-1) at the distal ends of the excretory canals. In addition, exc-7 mutants exhibit synergistic excretory canal defects with mutations in sma-1, and EXC-7 binds sma-1 mRNA. These data imply that EXC-7 protein may affect expression of sma-1 and other genes to effect proper development of the excretory canals.
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Affiliation(s)
- Masaki Fujita
- Department of Biology, Graduate School of Science and Technology, Kobe University, 1-1 Rokkodaicho, Nadaku, Kobe 657-8501, Japan
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24
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Abstract
As organisms have evolved in size and complexity, tubular systems have developed to enable the efficient transport of substances into and out of tissues. These tubular systems are generated using strategies that are based on common elements of cell behaviour, including cell polarization, tube migration to target sites, cell-fate diversification and localization of specialized cells to different regions of the tube system. Using examples from both invertebrate and vertebrate systems, this review highlights progress in understanding these basic principles and briefly discusses the possible evolution of strategies to regulate the morphogenesis of tubular systems.
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Affiliation(s)
- Brigid L M Hogan
- Howard Hughes Medical Institute and Department of Cell and Developmental Biology, Vanderbilt Medical Center, Nashville, Tennessee 37232-2175, USA.
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25
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Schmidt A, Hall A. Guanine nucleotide exchange factors for Rho GTPases: turning on the switch. Genes Dev 2002; 16:1587-609. [PMID: 12101119 DOI: 10.1101/gad.1003302] [Citation(s) in RCA: 917] [Impact Index Per Article: 41.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Anja Schmidt
- MRC Laboratory for Molecular Cell Biology, Cancer Research UK Oncogene and Signal Transduction Group, University College London, London WC1E 6BT, UK.
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