Microtubule Function
Published by Anonymous on 2007/9/28 (4920 reads)
1: Int J Biochem Cell Biol. 2007;39(1):7-11. Epub 2006 Sep 1.
NEDD1: function in microtubule nucleation, spindle assembly and beyond.
Manning J, Kumar S.
Hanson Institute, Institute of Medical and Veterinary Science, PO Box 14, Rundle Mall, Adelaide, SA 5000, Australia.
Nedd1 was originally identified as a developmentally regulated gene in the mouse central nervous system. NEDD1 has homologues across a range of species, being particularly conserved in a region of WD40 repeats contained in the amino-terminal half of the protein. Human NEDD1 was recently found to localise to the centrosome and mitotic spindle. It binds to the components of the gamma-tubulin ring complex and target this complex to the centrosome and spindle. Depletion of NEDD1 causes loss of the gamma-tubulin ring complex from the centrosome and results in the failure of microtubule nucleation and spindle assembly. In addition, phosphorylation of NEDD1 during mitosis is critical for targeting gamma-tubulin to the spindle, but not the centrosome. There is still much unknown about the function of this protein and how it may be involved in development and disease. This short review summarises some of the recent work on NEDD1 and discusses how this interesting protein may have additional yet unexplored functions.
Publication Types:
Research Support, Non-U.S. Gov't
Review
PMID: 17005434 [PubMed - indexed for MEDLINE]
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2: Tanpakushitsu Kakusan Koso. 2006 May;51(6 Suppl):535-42.
[Structure and function of microtubule-associated proteins]
[Article in Japanese]
Kotani S, Matsusima K, Hisanaga S.
kotani-bio@kanagawa-u.ac.jp
Publication Types:
Review
PMID: 16719309 [PubMed - indexed for MEDLINE]
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3: J Muscle Res Cell Motil. 2006;27(2):161-71. Epub 2006 Feb 2.
Back on track - on the role of the microtubule for kinesin motility and cellular function.
Lakämper S, Meyhöfer E.
Physics of Complex Systems, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV, Amsterdam, The Netherlands.
The evolution of cytoskeletal filaments (actin- and intermediate-filaments, and the microtubules) and their associated motor- and non-motor-proteins has enabled the eukaryotic cell to achieve complex organizational and structural tasks. This ability to control cellular transport processes and structures allowed for the development of such complex cellular organelles like cilia or flagella in single-cell organisms and made possible the development and differentiation of multi-cellular organisms with highly specialized, polarized cells. Also, the faithful segregation of large amounts of genetic information during cell division relies crucially on the reorganization and control of the cytoskeleton, making the cytoskeleton a key prerequisite for the development of highly complex genomes. Therefore, it is not surprising that the eukaryotic cell continuously invests considerable resources in the establishment, maintenance, modification and rearrangement of the cytoskeletal filaments and the regulation of its interaction with accessory proteins. Here we review the literature on the interaction between microtubules and motor-proteins of the kinesin-family. Our particular interest is the role of the microtubule in the regulation of kinesin motility and cellular function. After an introduction of the kinesin-microtubule interaction we focus on two interrelated aspects: (1) the active allosteric participation of the microtubule during the interaction with kinesins in general and (2) the possible regulatory role of post-translational modifications of the microtubule in the kinesin-microtubule interaction.
Publication Types:
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
Review
PMID: 16453157 [PubMed - indexed for MEDLINE]
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4: Biochim Biophys Acta. 2005 Jan 3;1739(2-3):268-79.
Inability of tau to properly regulate neuronal microtubule dynamics: a loss-of-function mechanism by which tau might mediate neuronal cell death.
Feinstein SC, Wilson L.
Neuroscience Research Institute, Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA 93106, USA. feinstei@lifesci.ucsb.edu
Interest in the microtubule-associated protein tau stems from its critical roles in neural development and maintenance, as well as its role in Alzheimer's, FTDP-17 and related neurodegenerative diseases. Under normal circumstances, tau performs its functions by binding to microtubules and powerfully regulating their stability and growing and shortening dynamics. On the other hand, genetic analyses have established a clear cause-and-effect relationship between tau dysfunction/mis-regulation and neuronal cell death and dementia in FTDP-17, but the molecular basis of tau's destructive action(s) remains poorly understood. One attractive model suggests that the intracellular accumulation of abnormal tau aggregates causes cell death, i.e., a gain-of-toxic function model. Here, we describe the evidence and arguments for an alternative loss-of-function model in which tau-mediated neuronal cell death is caused by the inability of affected cells to properly regulate their microtubule dynamic due to mis-regulation by tau. In support of this model, our recent data demonstrate that missense FTDP-17 mutations that alter amino acid residues near tau's microtubule binding region strikingly modify the ability of tau to modulate microtubule dynamics. Additional recent data from our labs support the notion that the same dysfunction occurs in the FTDP-17 regulatory mutations that alter tau RNA splicing patterns. Our model posits that the dynamics of microtubules in neuronal cells must be tightly regulated to enable them to carry out their diverse functions, and that microtubules that are either over-stabilized or under-stabilized, that is, outside an acceptable window of dynamic activity, lead to neurodegeneration. An especially attractive aspect of this model is that it readily accommodates both the structural and regulatory classes of FTDP-17 mutations.
Publication Types:
Research Support, U.S. Gov't, P.H.S.
Review
PMID: 15615645 [PubMed - indexed for MEDLINE]
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5: Int Rev Cytol. 2004;239:179-272.
MAPping the eukaryotic tree of life: structure, function, and evolution of the MAP215/Dis1 family of microtubule-associated proteins.
Gard DL, Becker BE, Josh Romney S.
Department of Biology, University of Utah, Salt Lake City, Utah 84112-0840, USA.
The MAP215/Dis1 family of proteins is an evolutionarily ancient family of microtubule-associated proteins, with characterized members in all major kingdoms of eukaryotes, including fungi (Stu2 in S. cerevisiae, Dis1 and Alp14 in S. pombe), Dictyostelium (DdCP224), plants (Mor1 in A. thaliana and TMBP200 in N. tabaccum), and animals (Zyg9 in C. elegans, Msps in Drosophila, XMAP215 in Xenopus, and ch-TOG in humans). All MAP215/Dis1 proteins (with the exception of those in plants) localize to microtubule-organizing centers (MTOCs), including spindle pole bodies in yeast and centrosomes in animals, and all bind to microtubules in vitro and?or in vivo. Diverse roles in regulating microtubule assembly and organization have been proposed for individual family members, and a substantial body of evidence suggests that MAP215/Dis1-related proteins play critical roles in the assembly and function of the meiotic/mitotic spindles and/or cell division. An extensive search of public databases (including both EST and genome databases) identified partial sequences predicted to encode more than three dozen new members of the MAP215/Dis1 family, including putative MAP215/Dis1-related proteins in Giardia lamblia and four other protists, sixteen additional species of fungi, six plants, and twelve animals. The structure and function of MAP215/Dis1 proteins are discussed in relation to the evolution of this ancient family of microtubule-associated proteins.
Publication Types:
Research Support, U.S. Gov't, Non-P.H.S.
Review
PMID: 15464854 [PubMed - indexed for MEDLINE]
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6: Curr Opin Cell Biol. 2004 Aug;16(4):443-50.
Microtubule-dependent transport in neurons: steps towards an understanding of regulation, function and dysfunction.
Guzik BW, Goldstein LS.
Howard Hughes Medical Institute, Department of Cellular and Molecular Medicine, School of Medicine, University of California, San Diego, La Jolla, California 92093-0683, USA.
Intracellular transport by microtubule-dependent motors is crucial for neuronal survival and function. Recent advances reveal novel strategies for the regulation of transport and the attachment of motors to cargoes. Current findings also illustrate the importance of directed transport in neuronal biology, including microtubule-motor-dependent transduction of neurotrophic signals and axonal damage signal complexes. Furthermore, recent data implicating the dysfunction of microtubule-dependent transport in the cause and development of several neurodegenerative diseases provides evidence for the vital role of transport in neuronal and organismal function.
Publication Types:
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.
Review
PMID: 15261678 [PubMed - indexed for MEDLINE]
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7: Nat Rev Mol Cell Biol. 2003 Dec;4(12):938-47.
Post-translational modifications regulate microtubule function.
Westermann S, Weber K.
Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA. swesterm@uclink.berkeley.edu
Publication Types:
Research Support, Non-U.S. Gov't
Review
PMID: 14685172 [PubMed - indexed for MEDLINE]
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8: Traffic. 2004 Jan;5(1):1-9.
Microtubule organization and function in epithelial cells.
Müsch A.
Dyson Institute of Vision Research; Weill Medical College of Cornell University, New York, 10021, USA. amuesch@mail.med.cornell.edu
Microtubules are essential for many aspects of polarity in multicellular organisms, ranging from the asymmetric distribution of cell-fate determinants in the one-cell embryo to the transient polarity generated in migrating fibroblasts. Epithelial cells exhibit permanent cell polarity characterized by apical and basolateral surface domains of distinct protein and lipid composition that are segregated by tight junctions. They are also endowed with a microtubule network that reflects the asymmetry of their cell surface: microtubule minus-ends face the apical- and microtubule plus-ends the basal domain. Strikingly, the formation of distinct surface domains during epithelial differentiation is accompanied by the re-organization of microtubules from a uniform array focused at the centrosome to the noncentrosomal network that aligns along the apico-basolateral polarity axis. The significance of this coincidence for epithelial morphogenesis and the signaling mechanisms that drive microtubule repolymerization in developing epithelia remain major unresolved questions that we are only beginning to address. Studies in cultured polarized epithelial cells have established that microtubules serve as tracks that facilitate targeted vesicular transport. Novel findings suggest, moreover, that microtubule-based transport promotes protein sorting, and even the generation of transport carriers in the endo- and exocytic pathways.
Publication Types:
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.
Review
PMID: 14675420 [PubMed - indexed for MEDLINE]
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9: J Neurobiol. 2004 Jan;58(1):48-59.
Microtubule-associated protein 1B function during normal development, regeneration, and pathological conditions in the nervous system.
Gonzalez-Billault C, Jimenez-Mateos EM, Caceres A, Diaz-Nido J, Wandosell F, Avila J.
Centro de Biologia Molecular Severo Ochoa (CSIC-UAM), Cantoblanco 28049, Madrid, Spain.
Microtubule-associated protein 1B is the first MAP to be expressed during the development of the nervous system. Several different approaches have revealed that MAP1B function is associated with microtubule and actin microfilament polymerization and dynamics. In recent years, the generation of molecular models to inactivate MAP1B function in invertebrates and mammals has sparked some controversy about the real role of MAP1B. Despite discrepancies between some studies, it is clear that MAP1B plays a principal role in the development of the nervous system. In this article, we summarize the evidence for MAP1B function in a wide variety of cellular processes implicated in the proper construction of the nervous system. We also discuss the role of MAP1B in pathological processes. Copyright 2003 Wiley Periodicals, Inc. J Neurobiol 58: 48-59, 2004
Publication Types:
Research Support, Non-U.S. Gov't
Review
PMID: 14598369 [PubMed - indexed for MEDLINE]
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10: Curr Opin Cell Biol. 2003 Feb;15(1):48-53.
A plus-end raft to control microtubule dynamics and function.
Galjart N, Perez F.
Department of Cell Biology and Genetics, Erasmus University, PO Box 1738, 3000 DR Rotterdam, The Netherlands. galjart@ch1.fgg.eur.nl
Cells require a properly oriented and organised microtubule array to transmit positional information. Recent data have revealed a heterogeneous population of microtubule-binding proteins that accumulates mainly at distal ends of polymerising microtubules. Two mechanisms may account for this concentration: transient immobilisation, which involves association of proteins with growing ends, followed by release more proximally; and deposition at ends via a molecular motor. As with lipid rafts, protein concentration at distal ends may allow a cascade of interactions in the restricted area of a microtubule plus end. This may, in turn, control the dynamic behaviour of this cytoskeletal network and its anchoring to other structures.
Publication Types:
Review
PMID: 12517703 [PubMed - indexed for MEDLINE]
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11: Annu Rev Biophys Biomol Struct. 2001;30:397-420.
Structural insight into microtubule function.
Nogales E.
Department of Molecular and Cell Biology, University of California, Berkeley, and Lawrence Berkeley National Laboratory, Berkeley California 94720, USA. ENOGALES@LBL.GOV
Microtubules are polymers that are essential for, among other functions, cell transport and cell division in all eukaryotes. The regulation of the microtubule system includes transcription of different tubulin isotypes, folding of alpha/beta-tubulin heterodimers, post-translation modification of tubulin, and nucleotide-based microtubule dynamics, as well as interaction with numerous microtubule-associated proteins that are themselves regulated. The result is the precise temporal and spatial pattern of microtubules that is observed throughout the cell cycle. The recent high-resolution analysis of the structure of tubulin and the microtubule has brought new insight to the study of microtubule function and regulation, as well as the mode of action of antimitotic drugs that disrupt normal microtubule behavior. The combination of structural, genetic, biochemical, and biophysical data should soon give us a fuller understanding of the exquisite details in the regulation of the microtubule cytoskeleton.
Publication Types:
Review
PMID: 11441808 [PubMed - indexed for MEDLINE]
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12: Histol Histopathol. 2000 Oct;15(4):1177-83.
Molecular genetic approaches to microtubule-associated protein function.
González-Billault C, Avila J.
Center of Molecular Biology Severo Ochoa, Universidad Autónoma de Madrid, Spain.
Protein function in vivo can be studied by deleting (knock-out) the gene that encodes it, and search for the consequences. This procedure involves different technologies, including recombinant DNA procedures, cell biology methods and histological and immunocytochemical analysis. In this work we have reviewed these procedures when they have been applied to ascertain the function of several microtubule-associated proteins. These proteins have been previously involved, through in vitro experiments, in having a role in the microtubule stabilization. Here, we will summarize the generation and characterization of different microtubule-associated protein knock-out mice. Special attention will be paid to MAP1B knock-out mice. Amongst the different MAPs knock-out mice these show the strongest phenotype, the most likely for being MAP1B, the MAP that is expressed earliest in neurogenesis. Molecular genetics could be considered as a valid and useful procedure to truly establish the in vivo functions of a protein, although it is necessary to be aware of possible artifacts such as the generation of some kinds of RNA alternative splicing. To avoid this the best strategy to be used must consider the deletion of the exon that contains the functional domains of the protein.
Publication Types:
Research Support, Non-U.S. Gov't
Review
PMID: 11005243 [PubMed - indexed for MEDLINE]
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13: Annu Rev Biochem. 2000;69:277-302.
Structural insights into microtubule function.
Nogales E.
Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California 94720, USA. ENOGALES@LBL.GOV
Microtubules are polymers that are essential for, among other functions, cell transport and cell division in all eukaryotes. The regulation of the microtubule system includes transcription of different tubulin isotypes, folding of /¿-tubulin heterodimers, post-translation modification of tubulin, and nucleotide-based microtubule dynamics, as well as interaction with numerous microtubule-associated proteins that are themselves regulated. The result is the precise temporal and spatial pattern of microtubules that is observed throughout the cell cycle. The recent high-resolution analysis of the structure of tubulin and the microtubule has brought new insight to the study of microtubule function and regulation, as well as the mode of action of antimitotic drugs that disrupt normal microtubule behavior. The combination of structural, genetic, biochemical, and biophysical data should soon give us a fuller understanding of the exquisite details in the regulation of the microtubule cytoskeleton.
Publication Types:
Review
PMID: 10966460 [PubMed - indexed for MEDLINE]
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14: Prog Neurobiol. 2000 Jun;61(2):133-68.
Phosphorylation of microtubule-associated protein 2 (MAP2) and its relevance for the regulation of the neuronal cytoskeleton function.
Sánchez C, Díaz-Nido J, Avila J.
Centro de Biología Molecular "Severo Ochoa", Facultad de Ciencias, Universidad Autónoma de Madrid (CSIC-UAM), Cantoblanco, 28049, Madrid, Spain. csanchez@cbm.uam.es
Neurons, the basic information processing units of the nervous system, are characterized by a complex polar morphology which is essential for their function. To attain their precise morphology, neurons extend cytoplasmatic processes (axons and dendrites) and establish synaptic connections in a highly regulated way. Additionally, neurons are also subjected to small plastic changes at the adult stage which serve to regulate synaptic transmission. Every step of neuronal development is genetically controlled by endogenous determinants, as well as by environmental signals including intercellular contacts, extracellular matrix and diffusible signals. Cytoskeletal components are among the main protein targets modified in response to most of those extracellular signals which ultimately determine neuronal morphology. One of the major mechanisms controlling the neuronal cytoskeleton is the modification of the phosphorylation state of cytoskeletal proteins via changes in the relative activities of protein kinases and phosphatases within neurons. In particular, the microtubule-associated protein 2 (MAP2) family of proteins is an abundant group of cytoskeletal components which are predominantly expressed in neurons and serve as substrates for most of protein kinases and phosphatases present in neurons. MAP2 phosphorylation seems to control its association with the cytoskeleton and it is developmentally regulated. Moreover, MAP2 may perform many functions including the nucleation and stabilization of microtubules (and maybe microfilaments), the regulation of organelle transport within axons and dendrites, as well as the anchorage of regulatory proteins such as protein kinases which may be important for signal transduction. These putative functions of MAP2 have also been proposed to play important roles in the outgrowth of neuronal processes, synaptic plasticity and neuronal cell death. Thus, MAP2 constitutes an interesting case to understand the regulation of neuronal function by the alteration of the phosphorylation state of cytoskeletal proteins in response to different extracellular signals. Here we will review the current knowledge about the regulation of MAP2 function through phosphorylation/dephosphorylation and its relevance in the broader context of neuronal functions.
Publication Types:
Research Support, Non-U.S. Gov't
Review
PMID: 10704996 [PubMed - indexed for MEDLINE]
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15: Curr Opin Struct Biol. 1999 Apr;9(2):268-74.
Microtubule-based motor function in mitosis.
Heald R, Walczak CE.
Department of Molecular and Cell Biology, 311 LSA University of California, Berkeley, CA 94720-3200, USA. heald@socrates.berkeley.edu
Microtubule-based motors are essential both for the proper assembly of the mitotic spindle and for chromosome segregation. Mitotic motors in the yeast Saccharomyces cerevisiae exhibit either overlapping or opposing activities in order to achieve proper spindle function, whereas the analysis of motors using vertebrate cytoplasmic extracts has revealed less functional redundancy. In several systems, biochemical, genetic and two-hybrid approaches have been used both to identify associated nonmotor proteins and to address the molecular mechanisms behind kinetochore movements during chromosome alignment and segregation.
Publication Types:
Review
PMID: 10322211 [PubMed - indexed for MEDLINE]
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16: Biochim Biophys Acta. 1998 Aug 14;1404(1-2):113-26.
The role of microtubule-based motor proteins in maintaining the structure and function of the Golgi complex.
Burkhardt JK.
Department of Pathology, The University of Chicago, 5841 S. Maryland Ave. MC1089, Chicago, IL 60637, USA. jburkhar@flowcity.bsd.uchicago.edu
The intimate association between the Golgi complex and the microtubule cytoskeleton plays an important role in Golgi structure and function. Recent evidence indicates that the dynamic flow of material from the ER to the Golgi is crucial to maintaining the integrity of the Golgi complex and its characteristic location within the cell, and it is now clear that this flow is dependent on the ongoing activity of microtubule motor proteins. This review focuses primarily on recent microinjection and expression studies which have explored the role of individual microtubule motor proteins in controlling Golgi dynamics. The collective evidence shows that one or more isoforms of cytoplasmic dynein, together with its cofactor the dynactin complex, are required to maintain a juxtanuclear Golgi complex in fibroblasts. Although questions remain about how dynein and dynactin are linked to the Golgi, there is evidence that the Golgi-spectrin lattice is involved. Kinesin and kinesin-like proteins appear to play a smaller role in Golgi dynamics, though this may be very cell-type specific. Moreover, new evidence about the role of kinesin family members continues to emerge. Thanks in part to recent advances in our understanding of these molecular motors, our current view of the Golgi complex is of an organelle in flux, undergoing constant renewal. Future research will be aimed at elucidating how and to what extent these motor proteins function as regulators of Golgi function.
Publication Types:
Review
PMID: 9714769 [PubMed - indexed for MEDLINE]
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17: Cell. 1997 Jun 13;89(6):825-8.
Microtubule function in morphological differentiation: growth zones and growth cones.
Vega LR, Solomon F.
Department of Biology and Center for Cancer Research, Massachusetts Institute of Technology, Cambridge 02139, USA.
Publication Types:
Review
PMID: 9200600 [PubMed - indexed for MEDLINE]
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18: Yakugaku Zasshi. 1994 Jul;114(7):435-47.
[Structure and function of mammalian brain microtubule-associated proteins]
[Article in Japanese]
Fujii T.
Department of Functional Polymer Science, Faculty of Textile Science and Technology, Shinshu University, Ueda, Japan.
Cytoplasmic microtubules are fibrous intracellular organelles found in almost all eukaryotic cells and play an important role in maintenance of cell shape, cell division, axonal transport, secretion and receptor activity. Besides tubulin dimers, microtubule proteins consist of several other components called MAPs which promote microtubule assembly and form long filamentous projection on the surface of the polymer. In mammalian brain, two classes of MAPs have been characterized; one is structural MAPs including MAP1 (1A and 1B), MAP2 (2A, 2B and 2C) and tau which function in the morphogenesis and maintenance of neural tissues and cells, and the other contains motor MAPs (kinesin and MAP1C) which are related to translocation of vesicles along microtubules in axon and to mitosis. The primary sequences of MAPs have been determined from their cDNAs. The functions of structural MAPs are modulated by their binding to other intracellular components, different expressions of isoforms during brain development and phosphorylation-dephosphorylation by various protein kinases and phosphatases. Biochemical characterization of MAP2 and tau have been well investigated. However, little is known about the function of MAP1 under the biochemical level, because MAP1 is unstable and high sensitive to proteases. We have developed a simple and rapid purification procedure for MAP1 using poly (L-aspartic acid) and taxol, and observed MAP1-F-actin interaction as well as MAP1-microtubules interaction. Recently, we have found that three specific kinases which can phosphorylate MAP1A and 1B are associated with MAP1 preparation and called it MAP1 kinase. Some evidence suggest that one of them is an unknown kinase and others are casein kinase I- and II-like kinases. Further studies to examine MAP1 kinase and phosphorylation of MAP1 provide a valuable insight for understanding thoroughly the microtubule-mediated functions.
Publication Types:
English Abstract
Review
PMID: 7932091 [PubMed - indexed for MEDLINE]
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19: Cell Motil Cytoskeleton. 1994;28(3):195-8.
Microtubule-associated protein function: lessons from expression in Spodoptera frugiperda cells.
Kosik KS, McConlogue L.
Harvard Medical School, Department of Medicine, Brigham and Women's Hospital, Boston.
The phenotypes induced by the expression of neuronal microtubule-associated proteins (MAPs) in Sf9 cells have provided data on the in situ function of these proteins. Both MAP2 and tau can induce long processes in Sf9 cells, and the processes contain bundles of microtubules. In both cases the microtubules are aligned with their plus ends distal. Tau expression usually induces a single process that is unbranched and of uniform caliber. Processes can form even when the cells are grown in suspension. Microtubules do not extend all the way to the tip; instead the terminal region contains an actin-rich meshwork. Taxol treatment of Sf9 cells also induces the assembly of microtubules into bundles but does not induce process formation in Sf9 cells. Therefore the in vitro properties of tau as a molecule capable of assembling, stabilizing, and bundling microtubules do not fully account for the in vivo ability of tau alone to transduce microtubule assembly into a change in cell shape. The morphological features of the processes induced by MAP2 differ in highly informative ways.
Publication Types:
Review
PMID: 7954847 [PubMed - indexed for MEDLINE]
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20: Int Rev Cytol. 1994;151:67-137.
Diverse distribution and function of fibrous microtubule-associated proteins in the nervous system.
Schoenfeld TA, Obar RA.
Department of Psychology, Clark University, Worcester, Massachusetts 01610.
Publication Types:
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.
Review
PMID: 7912236 [PubMed - indexed for MEDLINE]
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21: Biochem Cell Biol. 1992 Oct-Nov;70(10-11):835-41.
Towards an understanding of microtubule function and cell organization: an overview.
MacRae TH.
Department of Biology, Dalhousie University, Halifax, N.S., Canada.
Microtubules exhibit dynamic instability, converting abruptly between assembly and disassembly with continued growth dependent on the presence of a tubulin-GTP cap at the plus end of the organelle. Tubulin, the main structural protein of microtubules, is a heterodimer composed of related polypeptides termed alpha-tubulin and beta-tubulin. Most eukaryotic cells possess several isoforms of the alpha- and beta-tubulins, as well as gamma-tubulin, an isoform restricted to the centrosome. The isoforms of tubulin arise either as the products of different genes or by posttranslational processes and their synthesis is subject to regulation. Tubulin isoforms coassemble with one another and isoform composition does not appear to determine whether a microtubule is able to carry out one particular activity or another. However, the posttranslational modification of polymerized tubulin may provide chemical signals which designate microtubules for a certain function. Microtubules interact with proteins called microtubule-associated proteins (MAPs) and they can be divided into two groups. The structural MAPs stimulate tubulin assembly, enhance microtubule stability, and influence the spatial distribution of microtubules within cells. The dynamic MAPs take advantage of microtubule polarity and organization to vectorially translocate cellular components. The interactions between microtubules and MAPs contribute to the structural-functional integration that characterizes eukaryotic cells.
Publication Types:
Review
PMID: 1297349 [PubMed - indexed for MEDLINE]
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22: Pharmacol Ther. 1991 Nov;52(2):159-71.
Resistance to antimitotic agents as genetic probes of microtubule structure and function.
Cabral F, Barlow SB.
Department of Pharmacology, University of Texas Medical School, Houston 77225.
Much of our knowledge about microtubules has come from detailed morphological, biochemical, and cell biological studies. As more is learned about these organelles, questions regarding the in vivo regulation of their expression and function become increasingly important. Genetics provides an approach to address these more subtle questions in the living cell. Mammalian mutants with microtubule alterations have been isolated using selections for resistance to the cytotoxic effects of a number of antimitotic drugs. A subset of these mutants have clearly defined alterations in alpha- or in beta-tubulin, and these have been used to explore the mechanisms by which mammalian cells acquire resistance to this class of drugs. In addition, the mutants are providing valuable insights into how tubulin expression is regulated, into what factors determine the extent of microtubule assembly in living cells, into the domains of tubulin that are involved in assembly, and into the role of microtubules in essential cellular processes.
Publication Types:
Research Support, U.S. Gov't, P.H.S.
Review
PMID: 1818334 [PubMed - indexed for MEDLINE]
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23: Int Rev Cytol. 1991;124:217-73.
Molecular structure and function of microtubule-associated proteins.
Wiche G, Oberkanins C, Himmler A.
Institut für Biochemie, Universität Wien, Vienna, Austria.
Publication Types:
Research Support, Non-U.S. Gov't
Review
PMID: 2001917 [PubMed - indexed for MEDLINE]
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24: Annu Rev Cell Biol. 1991;7:93-116.
Microtubule dynamics: mechanism, regulation, and function.
Gelfand VI, Bershadsky AD.
Institute of Protein Research, Academy of Sciences of the USSR, Pushchino, Moscow Region.
Publication Types:
Review
PMID: 1809357 [PubMed - indexed for MEDLINE]
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25: Cell Motil Cytoskeleton. 1990;15(1):1-6.
The yeast microtubule cytoskeleton: genetic approaches to structure and function.
Stearns T.
Department of Biology, Massachusetts Institute of Technology, Cambridge.
Publication Types:
Review
PMID: 2403845 [PubMed - indexed for MEDLINE]
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26: Cell Motil Cytoskeleton. 1989;14(1):128-35.
Interacting genes identify interacting proteins involved in microtubule function in Drosophila.
Fuller MT, Regan CL, Green LL, Robertson B, Deuring R, Hays TS.
Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder 08309-00347.
Publication Types:
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.
Review
PMID: 2684419 [PubMed - indexed for MEDLINE]
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27: Annu Rev Cell Biol. 1988;4:527-49.
Microtubule dynamics and kinetochore function in mitosis.
Mitchison TJ.
Department of Pharmacology, University of California, San Francisco 94143.
Publication Types:
In Vitro
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.
Review
PMID: 3058165 [PubMed - indexed for MEDLINE]
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28: Oxf Surv Eukaryot Genes. 1984;1:36-60.
Tubulin genes and the diversity of microtubule function.
Cowan NJ.
Publication Types:
Review
PMID: 6400775 [PubMed - indexed for MEDLINE]
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29: Am J Pathol. 1976 Nov;85(2):395-418.
Impaired microtubule function correctable by cyclic GMP and cholinergic agonists in the Chediak-Higashi syndrome.
Oliver JM.
The Chediak-Higashi (CH) syndrome of man and several animal species is characterized by the presence of abnormal giant granules in all granule-containing cells and by defects in chemotaxis and lysosomal degranulation during phagocytosis in polymorphonuclear leukocytes (PMNs). Since similar functional abnormalities have been reported in normal PMNs following exposure to colchicine and other agents that disrupt microtubles it was proposed that microtubule function may be impaired in the CH syndrome. The mobility of concanavalin A (con A)-receptor complexes on PMN membranes was used to test microtubule integrity. Normal PMNs showed a uniform distribution of membrane-bound con A. By contrast, con A was aggregated into surface caps on both colchicine-treated normal PMNs and untreated PMNs from mice and a patient with CH syndrome. This result is consistent with impaired microtubule function in the CH cells. The spontaneous capping response of CH PMNs was inhibited by cyclic GMP and by cholinergic agonists that can elevate cyclic GMP levels in neutrophils. This raised the possibility that the microtubule defect in CH cells may be correctable by treatments that increase cyclic GMP generation. Direct evidence for both the absence of microtubule assembly in con A-treated PMNs from the CH patient and for normal microtubule assembly in CH PMNs incubated with cyclic GMP and cholinergic agonists prior to con A treatment was obtained by electron microscopy. In addition, evidence for a direct relationship between the microtubule defect and the development of giant lysosomes in CH cells was obtained. Thus, CH fibroblasts grown in vitro developed abnormal lysosomes in the majority of cells. However, the same cells cultured in the presence of cholinergic agonists developed a majority of lysosomes that were morphologically normal at the level of the light microscope. Similarly, granule morphology appeared normal in peripheral blood leukocytes from mice treated chronically in vivo with cholinergic agonists.
Publication Types:
Research Support, U.S. Gov't, P.H.S.
Review
PMID: 187062 [PubMed - indexed for MEDLINE]
NEDD1: function in microtubule nucleation, spindle assembly and beyond.
Manning J, Kumar S.
Hanson Institute, Institute of Medical and Veterinary Science, PO Box 14, Rundle Mall, Adelaide, SA 5000, Australia.
Nedd1 was originally identified as a developmentally regulated gene in the mouse central nervous system. NEDD1 has homologues across a range of species, being particularly conserved in a region of WD40 repeats contained in the amino-terminal half of the protein. Human NEDD1 was recently found to localise to the centrosome and mitotic spindle. It binds to the components of the gamma-tubulin ring complex and target this complex to the centrosome and spindle. Depletion of NEDD1 causes loss of the gamma-tubulin ring complex from the centrosome and results in the failure of microtubule nucleation and spindle assembly. In addition, phosphorylation of NEDD1 during mitosis is critical for targeting gamma-tubulin to the spindle, but not the centrosome. There is still much unknown about the function of this protein and how it may be involved in development and disease. This short review summarises some of the recent work on NEDD1 and discusses how this interesting protein may have additional yet unexplored functions.
Publication Types:
Research Support, Non-U.S. Gov't
Review
PMID: 17005434 [PubMed - indexed for MEDLINE]
--------------------------------------------------------------------------------
2: Tanpakushitsu Kakusan Koso. 2006 May;51(6 Suppl):535-42.
[Structure and function of microtubule-associated proteins]
[Article in Japanese]
Kotani S, Matsusima K, Hisanaga S.
kotani-bio@kanagawa-u.ac.jp
Publication Types:
Review
PMID: 16719309 [PubMed - indexed for MEDLINE]
--------------------------------------------------------------------------------
3: J Muscle Res Cell Motil. 2006;27(2):161-71. Epub 2006 Feb 2.
Back on track - on the role of the microtubule for kinesin motility and cellular function.
Lakämper S, Meyhöfer E.
Physics of Complex Systems, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV, Amsterdam, The Netherlands.
The evolution of cytoskeletal filaments (actin- and intermediate-filaments, and the microtubules) and their associated motor- and non-motor-proteins has enabled the eukaryotic cell to achieve complex organizational and structural tasks. This ability to control cellular transport processes and structures allowed for the development of such complex cellular organelles like cilia or flagella in single-cell organisms and made possible the development and differentiation of multi-cellular organisms with highly specialized, polarized cells. Also, the faithful segregation of large amounts of genetic information during cell division relies crucially on the reorganization and control of the cytoskeleton, making the cytoskeleton a key prerequisite for the development of highly complex genomes. Therefore, it is not surprising that the eukaryotic cell continuously invests considerable resources in the establishment, maintenance, modification and rearrangement of the cytoskeletal filaments and the regulation of its interaction with accessory proteins. Here we review the literature on the interaction between microtubules and motor-proteins of the kinesin-family. Our particular interest is the role of the microtubule in the regulation of kinesin motility and cellular function. After an introduction of the kinesin-microtubule interaction we focus on two interrelated aspects: (1) the active allosteric participation of the microtubule during the interaction with kinesins in general and (2) the possible regulatory role of post-translational modifications of the microtubule in the kinesin-microtubule interaction.
Publication Types:
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
Review
PMID: 16453157 [PubMed - indexed for MEDLINE]
--------------------------------------------------------------------------------
4: Biochim Biophys Acta. 2005 Jan 3;1739(2-3):268-79.
Inability of tau to properly regulate neuronal microtubule dynamics: a loss-of-function mechanism by which tau might mediate neuronal cell death.
Feinstein SC, Wilson L.
Neuroscience Research Institute, Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA 93106, USA. feinstei@lifesci.ucsb.edu
Interest in the microtubule-associated protein tau stems from its critical roles in neural development and maintenance, as well as its role in Alzheimer's, FTDP-17 and related neurodegenerative diseases. Under normal circumstances, tau performs its functions by binding to microtubules and powerfully regulating their stability and growing and shortening dynamics. On the other hand, genetic analyses have established a clear cause-and-effect relationship between tau dysfunction/mis-regulation and neuronal cell death and dementia in FTDP-17, but the molecular basis of tau's destructive action(s) remains poorly understood. One attractive model suggests that the intracellular accumulation of abnormal tau aggregates causes cell death, i.e., a gain-of-toxic function model. Here, we describe the evidence and arguments for an alternative loss-of-function model in which tau-mediated neuronal cell death is caused by the inability of affected cells to properly regulate their microtubule dynamic due to mis-regulation by tau. In support of this model, our recent data demonstrate that missense FTDP-17 mutations that alter amino acid residues near tau's microtubule binding region strikingly modify the ability of tau to modulate microtubule dynamics. Additional recent data from our labs support the notion that the same dysfunction occurs in the FTDP-17 regulatory mutations that alter tau RNA splicing patterns. Our model posits that the dynamics of microtubules in neuronal cells must be tightly regulated to enable them to carry out their diverse functions, and that microtubules that are either over-stabilized or under-stabilized, that is, outside an acceptable window of dynamic activity, lead to neurodegeneration. An especially attractive aspect of this model is that it readily accommodates both the structural and regulatory classes of FTDP-17 mutations.
Publication Types:
Research Support, U.S. Gov't, P.H.S.
Review
PMID: 15615645 [PubMed - indexed for MEDLINE]
--------------------------------------------------------------------------------
5: Int Rev Cytol. 2004;239:179-272.
MAPping the eukaryotic tree of life: structure, function, and evolution of the MAP215/Dis1 family of microtubule-associated proteins.
Gard DL, Becker BE, Josh Romney S.
Department of Biology, University of Utah, Salt Lake City, Utah 84112-0840, USA.
The MAP215/Dis1 family of proteins is an evolutionarily ancient family of microtubule-associated proteins, with characterized members in all major kingdoms of eukaryotes, including fungi (Stu2 in S. cerevisiae, Dis1 and Alp14 in S. pombe), Dictyostelium (DdCP224), plants (Mor1 in A. thaliana and TMBP200 in N. tabaccum), and animals (Zyg9 in C. elegans, Msps in Drosophila, XMAP215 in Xenopus, and ch-TOG in humans). All MAP215/Dis1 proteins (with the exception of those in plants) localize to microtubule-organizing centers (MTOCs), including spindle pole bodies in yeast and centrosomes in animals, and all bind to microtubules in vitro and?or in vivo. Diverse roles in regulating microtubule assembly and organization have been proposed for individual family members, and a substantial body of evidence suggests that MAP215/Dis1-related proteins play critical roles in the assembly and function of the meiotic/mitotic spindles and/or cell division. An extensive search of public databases (including both EST and genome databases) identified partial sequences predicted to encode more than three dozen new members of the MAP215/Dis1 family, including putative MAP215/Dis1-related proteins in Giardia lamblia and four other protists, sixteen additional species of fungi, six plants, and twelve animals. The structure and function of MAP215/Dis1 proteins are discussed in relation to the evolution of this ancient family of microtubule-associated proteins.
Publication Types:
Research Support, U.S. Gov't, Non-P.H.S.
Review
PMID: 15464854 [PubMed - indexed for MEDLINE]
--------------------------------------------------------------------------------
6: Curr Opin Cell Biol. 2004 Aug;16(4):443-50.
Microtubule-dependent transport in neurons: steps towards an understanding of regulation, function and dysfunction.
Guzik BW, Goldstein LS.
Howard Hughes Medical Institute, Department of Cellular and Molecular Medicine, School of Medicine, University of California, San Diego, La Jolla, California 92093-0683, USA.
Intracellular transport by microtubule-dependent motors is crucial for neuronal survival and function. Recent advances reveal novel strategies for the regulation of transport and the attachment of motors to cargoes. Current findings also illustrate the importance of directed transport in neuronal biology, including microtubule-motor-dependent transduction of neurotrophic signals and axonal damage signal complexes. Furthermore, recent data implicating the dysfunction of microtubule-dependent transport in the cause and development of several neurodegenerative diseases provides evidence for the vital role of transport in neuronal and organismal function.
Publication Types:
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.
Review
PMID: 15261678 [PubMed - indexed for MEDLINE]
--------------------------------------------------------------------------------
7: Nat Rev Mol Cell Biol. 2003 Dec;4(12):938-47.
Post-translational modifications regulate microtubule function.
Westermann S, Weber K.
Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA. swesterm@uclink.berkeley.edu
Publication Types:
Research Support, Non-U.S. Gov't
Review
PMID: 14685172 [PubMed - indexed for MEDLINE]
--------------------------------------------------------------------------------
8: Traffic. 2004 Jan;5(1):1-9.
Microtubule organization and function in epithelial cells.
Müsch A.
Dyson Institute of Vision Research; Weill Medical College of Cornell University, New York, 10021, USA. amuesch@mail.med.cornell.edu
Microtubules are essential for many aspects of polarity in multicellular organisms, ranging from the asymmetric distribution of cell-fate determinants in the one-cell embryo to the transient polarity generated in migrating fibroblasts. Epithelial cells exhibit permanent cell polarity characterized by apical and basolateral surface domains of distinct protein and lipid composition that are segregated by tight junctions. They are also endowed with a microtubule network that reflects the asymmetry of their cell surface: microtubule minus-ends face the apical- and microtubule plus-ends the basal domain. Strikingly, the formation of distinct surface domains during epithelial differentiation is accompanied by the re-organization of microtubules from a uniform array focused at the centrosome to the noncentrosomal network that aligns along the apico-basolateral polarity axis. The significance of this coincidence for epithelial morphogenesis and the signaling mechanisms that drive microtubule repolymerization in developing epithelia remain major unresolved questions that we are only beginning to address. Studies in cultured polarized epithelial cells have established that microtubules serve as tracks that facilitate targeted vesicular transport. Novel findings suggest, moreover, that microtubule-based transport promotes protein sorting, and even the generation of transport carriers in the endo- and exocytic pathways.
Publication Types:
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.
Review
PMID: 14675420 [PubMed - indexed for MEDLINE]
--------------------------------------------------------------------------------
9: J Neurobiol. 2004 Jan;58(1):48-59.
Microtubule-associated protein 1B function during normal development, regeneration, and pathological conditions in the nervous system.
Gonzalez-Billault C, Jimenez-Mateos EM, Caceres A, Diaz-Nido J, Wandosell F, Avila J.
Centro de Biologia Molecular Severo Ochoa (CSIC-UAM), Cantoblanco 28049, Madrid, Spain.
Microtubule-associated protein 1B is the first MAP to be expressed during the development of the nervous system. Several different approaches have revealed that MAP1B function is associated with microtubule and actin microfilament polymerization and dynamics. In recent years, the generation of molecular models to inactivate MAP1B function in invertebrates and mammals has sparked some controversy about the real role of MAP1B. Despite discrepancies between some studies, it is clear that MAP1B plays a principal role in the development of the nervous system. In this article, we summarize the evidence for MAP1B function in a wide variety of cellular processes implicated in the proper construction of the nervous system. We also discuss the role of MAP1B in pathological processes. Copyright 2003 Wiley Periodicals, Inc. J Neurobiol 58: 48-59, 2004
Publication Types:
Research Support, Non-U.S. Gov't
Review
PMID: 14598369 [PubMed - indexed for MEDLINE]
--------------------------------------------------------------------------------
10: Curr Opin Cell Biol. 2003 Feb;15(1):48-53.
A plus-end raft to control microtubule dynamics and function.
Galjart N, Perez F.
Department of Cell Biology and Genetics, Erasmus University, PO Box 1738, 3000 DR Rotterdam, The Netherlands. galjart@ch1.fgg.eur.nl
Cells require a properly oriented and organised microtubule array to transmit positional information. Recent data have revealed a heterogeneous population of microtubule-binding proteins that accumulates mainly at distal ends of polymerising microtubules. Two mechanisms may account for this concentration: transient immobilisation, which involves association of proteins with growing ends, followed by release more proximally; and deposition at ends via a molecular motor. As with lipid rafts, protein concentration at distal ends may allow a cascade of interactions in the restricted area of a microtubule plus end. This may, in turn, control the dynamic behaviour of this cytoskeletal network and its anchoring to other structures.
Publication Types:
Review
PMID: 12517703 [PubMed - indexed for MEDLINE]
--------------------------------------------------------------------------------
11: Annu Rev Biophys Biomol Struct. 2001;30:397-420.
Structural insight into microtubule function.
Nogales E.
Department of Molecular and Cell Biology, University of California, Berkeley, and Lawrence Berkeley National Laboratory, Berkeley California 94720, USA. ENOGALES@LBL.GOV
Microtubules are polymers that are essential for, among other functions, cell transport and cell division in all eukaryotes. The regulation of the microtubule system includes transcription of different tubulin isotypes, folding of alpha/beta-tubulin heterodimers, post-translation modification of tubulin, and nucleotide-based microtubule dynamics, as well as interaction with numerous microtubule-associated proteins that are themselves regulated. The result is the precise temporal and spatial pattern of microtubules that is observed throughout the cell cycle. The recent high-resolution analysis of the structure of tubulin and the microtubule has brought new insight to the study of microtubule function and regulation, as well as the mode of action of antimitotic drugs that disrupt normal microtubule behavior. The combination of structural, genetic, biochemical, and biophysical data should soon give us a fuller understanding of the exquisite details in the regulation of the microtubule cytoskeleton.
Publication Types:
Review
PMID: 11441808 [PubMed - indexed for MEDLINE]
--------------------------------------------------------------------------------
12: Histol Histopathol. 2000 Oct;15(4):1177-83.
Molecular genetic approaches to microtubule-associated protein function.
González-Billault C, Avila J.
Center of Molecular Biology Severo Ochoa, Universidad Autónoma de Madrid, Spain.
Protein function in vivo can be studied by deleting (knock-out) the gene that encodes it, and search for the consequences. This procedure involves different technologies, including recombinant DNA procedures, cell biology methods and histological and immunocytochemical analysis. In this work we have reviewed these procedures when they have been applied to ascertain the function of several microtubule-associated proteins. These proteins have been previously involved, through in vitro experiments, in having a role in the microtubule stabilization. Here, we will summarize the generation and characterization of different microtubule-associated protein knock-out mice. Special attention will be paid to MAP1B knock-out mice. Amongst the different MAPs knock-out mice these show the strongest phenotype, the most likely for being MAP1B, the MAP that is expressed earliest in neurogenesis. Molecular genetics could be considered as a valid and useful procedure to truly establish the in vivo functions of a protein, although it is necessary to be aware of possible artifacts such as the generation of some kinds of RNA alternative splicing. To avoid this the best strategy to be used must consider the deletion of the exon that contains the functional domains of the protein.
Publication Types:
Research Support, Non-U.S. Gov't
Review
PMID: 11005243 [PubMed - indexed for MEDLINE]
--------------------------------------------------------------------------------
13: Annu Rev Biochem. 2000;69:277-302.
Structural insights into microtubule function.
Nogales E.
Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California 94720, USA. ENOGALES@LBL.GOV
Microtubules are polymers that are essential for, among other functions, cell transport and cell division in all eukaryotes. The regulation of the microtubule system includes transcription of different tubulin isotypes, folding of /¿-tubulin heterodimers, post-translation modification of tubulin, and nucleotide-based microtubule dynamics, as well as interaction with numerous microtubule-associated proteins that are themselves regulated. The result is the precise temporal and spatial pattern of microtubules that is observed throughout the cell cycle. The recent high-resolution analysis of the structure of tubulin and the microtubule has brought new insight to the study of microtubule function and regulation, as well as the mode of action of antimitotic drugs that disrupt normal microtubule behavior. The combination of structural, genetic, biochemical, and biophysical data should soon give us a fuller understanding of the exquisite details in the regulation of the microtubule cytoskeleton.
Publication Types:
Review
PMID: 10966460 [PubMed - indexed for MEDLINE]
--------------------------------------------------------------------------------
14: Prog Neurobiol. 2000 Jun;61(2):133-68.
Phosphorylation of microtubule-associated protein 2 (MAP2) and its relevance for the regulation of the neuronal cytoskeleton function.
Sánchez C, Díaz-Nido J, Avila J.
Centro de Biología Molecular "Severo Ochoa", Facultad de Ciencias, Universidad Autónoma de Madrid (CSIC-UAM), Cantoblanco, 28049, Madrid, Spain. csanchez@cbm.uam.es
Neurons, the basic information processing units of the nervous system, are characterized by a complex polar morphology which is essential for their function. To attain their precise morphology, neurons extend cytoplasmatic processes (axons and dendrites) and establish synaptic connections in a highly regulated way. Additionally, neurons are also subjected to small plastic changes at the adult stage which serve to regulate synaptic transmission. Every step of neuronal development is genetically controlled by endogenous determinants, as well as by environmental signals including intercellular contacts, extracellular matrix and diffusible signals. Cytoskeletal components are among the main protein targets modified in response to most of those extracellular signals which ultimately determine neuronal morphology. One of the major mechanisms controlling the neuronal cytoskeleton is the modification of the phosphorylation state of cytoskeletal proteins via changes in the relative activities of protein kinases and phosphatases within neurons. In particular, the microtubule-associated protein 2 (MAP2) family of proteins is an abundant group of cytoskeletal components which are predominantly expressed in neurons and serve as substrates for most of protein kinases and phosphatases present in neurons. MAP2 phosphorylation seems to control its association with the cytoskeleton and it is developmentally regulated. Moreover, MAP2 may perform many functions including the nucleation and stabilization of microtubules (and maybe microfilaments), the regulation of organelle transport within axons and dendrites, as well as the anchorage of regulatory proteins such as protein kinases which may be important for signal transduction. These putative functions of MAP2 have also been proposed to play important roles in the outgrowth of neuronal processes, synaptic plasticity and neuronal cell death. Thus, MAP2 constitutes an interesting case to understand the regulation of neuronal function by the alteration of the phosphorylation state of cytoskeletal proteins in response to different extracellular signals. Here we will review the current knowledge about the regulation of MAP2 function through phosphorylation/dephosphorylation and its relevance in the broader context of neuronal functions.
Publication Types:
Research Support, Non-U.S. Gov't
Review
PMID: 10704996 [PubMed - indexed for MEDLINE]
--------------------------------------------------------------------------------
15: Curr Opin Struct Biol. 1999 Apr;9(2):268-74.
Microtubule-based motor function in mitosis.
Heald R, Walczak CE.
Department of Molecular and Cell Biology, 311 LSA University of California, Berkeley, CA 94720-3200, USA. heald@socrates.berkeley.edu
Microtubule-based motors are essential both for the proper assembly of the mitotic spindle and for chromosome segregation. Mitotic motors in the yeast Saccharomyces cerevisiae exhibit either overlapping or opposing activities in order to achieve proper spindle function, whereas the analysis of motors using vertebrate cytoplasmic extracts has revealed less functional redundancy. In several systems, biochemical, genetic and two-hybrid approaches have been used both to identify associated nonmotor proteins and to address the molecular mechanisms behind kinetochore movements during chromosome alignment and segregation.
Publication Types:
Review
PMID: 10322211 [PubMed - indexed for MEDLINE]
--------------------------------------------------------------------------------
16: Biochim Biophys Acta. 1998 Aug 14;1404(1-2):113-26.
The role of microtubule-based motor proteins in maintaining the structure and function of the Golgi complex.
Burkhardt JK.
Department of Pathology, The University of Chicago, 5841 S. Maryland Ave. MC1089, Chicago, IL 60637, USA. jburkhar@flowcity.bsd.uchicago.edu
The intimate association between the Golgi complex and the microtubule cytoskeleton plays an important role in Golgi structure and function. Recent evidence indicates that the dynamic flow of material from the ER to the Golgi is crucial to maintaining the integrity of the Golgi complex and its characteristic location within the cell, and it is now clear that this flow is dependent on the ongoing activity of microtubule motor proteins. This review focuses primarily on recent microinjection and expression studies which have explored the role of individual microtubule motor proteins in controlling Golgi dynamics. The collective evidence shows that one or more isoforms of cytoplasmic dynein, together with its cofactor the dynactin complex, are required to maintain a juxtanuclear Golgi complex in fibroblasts. Although questions remain about how dynein and dynactin are linked to the Golgi, there is evidence that the Golgi-spectrin lattice is involved. Kinesin and kinesin-like proteins appear to play a smaller role in Golgi dynamics, though this may be very cell-type specific. Moreover, new evidence about the role of kinesin family members continues to emerge. Thanks in part to recent advances in our understanding of these molecular motors, our current view of the Golgi complex is of an organelle in flux, undergoing constant renewal. Future research will be aimed at elucidating how and to what extent these motor proteins function as regulators of Golgi function.
Publication Types:
Review
PMID: 9714769 [PubMed - indexed for MEDLINE]
--------------------------------------------------------------------------------
17: Cell. 1997 Jun 13;89(6):825-8.
Microtubule function in morphological differentiation: growth zones and growth cones.
Vega LR, Solomon F.
Department of Biology and Center for Cancer Research, Massachusetts Institute of Technology, Cambridge 02139, USA.
Publication Types:
Review
PMID: 9200600 [PubMed - indexed for MEDLINE]
--------------------------------------------------------------------------------
18: Yakugaku Zasshi. 1994 Jul;114(7):435-47.
[Structure and function of mammalian brain microtubule-associated proteins]
[Article in Japanese]
Fujii T.
Department of Functional Polymer Science, Faculty of Textile Science and Technology, Shinshu University, Ueda, Japan.
Cytoplasmic microtubules are fibrous intracellular organelles found in almost all eukaryotic cells and play an important role in maintenance of cell shape, cell division, axonal transport, secretion and receptor activity. Besides tubulin dimers, microtubule proteins consist of several other components called MAPs which promote microtubule assembly and form long filamentous projection on the surface of the polymer. In mammalian brain, two classes of MAPs have been characterized; one is structural MAPs including MAP1 (1A and 1B), MAP2 (2A, 2B and 2C) and tau which function in the morphogenesis and maintenance of neural tissues and cells, and the other contains motor MAPs (kinesin and MAP1C) which are related to translocation of vesicles along microtubules in axon and to mitosis. The primary sequences of MAPs have been determined from their cDNAs. The functions of structural MAPs are modulated by their binding to other intracellular components, different expressions of isoforms during brain development and phosphorylation-dephosphorylation by various protein kinases and phosphatases. Biochemical characterization of MAP2 and tau have been well investigated. However, little is known about the function of MAP1 under the biochemical level, because MAP1 is unstable and high sensitive to proteases. We have developed a simple and rapid purification procedure for MAP1 using poly (L-aspartic acid) and taxol, and observed MAP1-F-actin interaction as well as MAP1-microtubules interaction. Recently, we have found that three specific kinases which can phosphorylate MAP1A and 1B are associated with MAP1 preparation and called it MAP1 kinase. Some evidence suggest that one of them is an unknown kinase and others are casein kinase I- and II-like kinases. Further studies to examine MAP1 kinase and phosphorylation of MAP1 provide a valuable insight for understanding thoroughly the microtubule-mediated functions.
Publication Types:
English Abstract
Review
PMID: 7932091 [PubMed - indexed for MEDLINE]
--------------------------------------------------------------------------------
19: Cell Motil Cytoskeleton. 1994;28(3):195-8.
Microtubule-associated protein function: lessons from expression in Spodoptera frugiperda cells.
Kosik KS, McConlogue L.
Harvard Medical School, Department of Medicine, Brigham and Women's Hospital, Boston.
The phenotypes induced by the expression of neuronal microtubule-associated proteins (MAPs) in Sf9 cells have provided data on the in situ function of these proteins. Both MAP2 and tau can induce long processes in Sf9 cells, and the processes contain bundles of microtubules. In both cases the microtubules are aligned with their plus ends distal. Tau expression usually induces a single process that is unbranched and of uniform caliber. Processes can form even when the cells are grown in suspension. Microtubules do not extend all the way to the tip; instead the terminal region contains an actin-rich meshwork. Taxol treatment of Sf9 cells also induces the assembly of microtubules into bundles but does not induce process formation in Sf9 cells. Therefore the in vitro properties of tau as a molecule capable of assembling, stabilizing, and bundling microtubules do not fully account for the in vivo ability of tau alone to transduce microtubule assembly into a change in cell shape. The morphological features of the processes induced by MAP2 differ in highly informative ways.
Publication Types:
Review
PMID: 7954847 [PubMed - indexed for MEDLINE]
--------------------------------------------------------------------------------
20: Int Rev Cytol. 1994;151:67-137.
Diverse distribution and function of fibrous microtubule-associated proteins in the nervous system.
Schoenfeld TA, Obar RA.
Department of Psychology, Clark University, Worcester, Massachusetts 01610.
Publication Types:
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.
Review
PMID: 7912236 [PubMed - indexed for MEDLINE]
--------------------------------------------------------------------------------
21: Biochem Cell Biol. 1992 Oct-Nov;70(10-11):835-41.
Towards an understanding of microtubule function and cell organization: an overview.
MacRae TH.
Department of Biology, Dalhousie University, Halifax, N.S., Canada.
Microtubules exhibit dynamic instability, converting abruptly between assembly and disassembly with continued growth dependent on the presence of a tubulin-GTP cap at the plus end of the organelle. Tubulin, the main structural protein of microtubules, is a heterodimer composed of related polypeptides termed alpha-tubulin and beta-tubulin. Most eukaryotic cells possess several isoforms of the alpha- and beta-tubulins, as well as gamma-tubulin, an isoform restricted to the centrosome. The isoforms of tubulin arise either as the products of different genes or by posttranslational processes and their synthesis is subject to regulation. Tubulin isoforms coassemble with one another and isoform composition does not appear to determine whether a microtubule is able to carry out one particular activity or another. However, the posttranslational modification of polymerized tubulin may provide chemical signals which designate microtubules for a certain function. Microtubules interact with proteins called microtubule-associated proteins (MAPs) and they can be divided into two groups. The structural MAPs stimulate tubulin assembly, enhance microtubule stability, and influence the spatial distribution of microtubules within cells. The dynamic MAPs take advantage of microtubule polarity and organization to vectorially translocate cellular components. The interactions between microtubules and MAPs contribute to the structural-functional integration that characterizes eukaryotic cells.
Publication Types:
Review
PMID: 1297349 [PubMed - indexed for MEDLINE]
--------------------------------------------------------------------------------
22: Pharmacol Ther. 1991 Nov;52(2):159-71.
Resistance to antimitotic agents as genetic probes of microtubule structure and function.
Cabral F, Barlow SB.
Department of Pharmacology, University of Texas Medical School, Houston 77225.
Much of our knowledge about microtubules has come from detailed morphological, biochemical, and cell biological studies. As more is learned about these organelles, questions regarding the in vivo regulation of their expression and function become increasingly important. Genetics provides an approach to address these more subtle questions in the living cell. Mammalian mutants with microtubule alterations have been isolated using selections for resistance to the cytotoxic effects of a number of antimitotic drugs. A subset of these mutants have clearly defined alterations in alpha- or in beta-tubulin, and these have been used to explore the mechanisms by which mammalian cells acquire resistance to this class of drugs. In addition, the mutants are providing valuable insights into how tubulin expression is regulated, into what factors determine the extent of microtubule assembly in living cells, into the domains of tubulin that are involved in assembly, and into the role of microtubules in essential cellular processes.
Publication Types:
Research Support, U.S. Gov't, P.H.S.
Review
PMID: 1818334 [PubMed - indexed for MEDLINE]
--------------------------------------------------------------------------------
23: Int Rev Cytol. 1991;124:217-73.
Molecular structure and function of microtubule-associated proteins.
Wiche G, Oberkanins C, Himmler A.
Institut für Biochemie, Universität Wien, Vienna, Austria.
Publication Types:
Research Support, Non-U.S. Gov't
Review
PMID: 2001917 [PubMed - indexed for MEDLINE]
--------------------------------------------------------------------------------
24: Annu Rev Cell Biol. 1991;7:93-116.
Microtubule dynamics: mechanism, regulation, and function.
Gelfand VI, Bershadsky AD.
Institute of Protein Research, Academy of Sciences of the USSR, Pushchino, Moscow Region.
Publication Types:
Review
PMID: 1809357 [PubMed - indexed for MEDLINE]
--------------------------------------------------------------------------------
25: Cell Motil Cytoskeleton. 1990;15(1):1-6.
The yeast microtubule cytoskeleton: genetic approaches to structure and function.
Stearns T.
Department of Biology, Massachusetts Institute of Technology, Cambridge.
Publication Types:
Review
PMID: 2403845 [PubMed - indexed for MEDLINE]
--------------------------------------------------------------------------------
26: Cell Motil Cytoskeleton. 1989;14(1):128-35.
Interacting genes identify interacting proteins involved in microtubule function in Drosophila.
Fuller MT, Regan CL, Green LL, Robertson B, Deuring R, Hays TS.
Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder 08309-00347.
Publication Types:
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.
Review
PMID: 2684419 [PubMed - indexed for MEDLINE]
--------------------------------------------------------------------------------
27: Annu Rev Cell Biol. 1988;4:527-49.
Microtubule dynamics and kinetochore function in mitosis.
Mitchison TJ.
Department of Pharmacology, University of California, San Francisco 94143.
Publication Types:
In Vitro
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.
Review
PMID: 3058165 [PubMed - indexed for MEDLINE]
--------------------------------------------------------------------------------
28: Oxf Surv Eukaryot Genes. 1984;1:36-60.
Tubulin genes and the diversity of microtubule function.
Cowan NJ.
Publication Types:
Review
PMID: 6400775 [PubMed - indexed for MEDLINE]
--------------------------------------------------------------------------------
29: Am J Pathol. 1976 Nov;85(2):395-418.
Impaired microtubule function correctable by cyclic GMP and cholinergic agonists in the Chediak-Higashi syndrome.
Oliver JM.
The Chediak-Higashi (CH) syndrome of man and several animal species is characterized by the presence of abnormal giant granules in all granule-containing cells and by defects in chemotaxis and lysosomal degranulation during phagocytosis in polymorphonuclear leukocytes (PMNs). Since similar functional abnormalities have been reported in normal PMNs following exposure to colchicine and other agents that disrupt microtubles it was proposed that microtubule function may be impaired in the CH syndrome. The mobility of concanavalin A (con A)-receptor complexes on PMN membranes was used to test microtubule integrity. Normal PMNs showed a uniform distribution of membrane-bound con A. By contrast, con A was aggregated into surface caps on both colchicine-treated normal PMNs and untreated PMNs from mice and a patient with CH syndrome. This result is consistent with impaired microtubule function in the CH cells. The spontaneous capping response of CH PMNs was inhibited by cyclic GMP and by cholinergic agonists that can elevate cyclic GMP levels in neutrophils. This raised the possibility that the microtubule defect in CH cells may be correctable by treatments that increase cyclic GMP generation. Direct evidence for both the absence of microtubule assembly in con A-treated PMNs from the CH patient and for normal microtubule assembly in CH PMNs incubated with cyclic GMP and cholinergic agonists prior to con A treatment was obtained by electron microscopy. In addition, evidence for a direct relationship between the microtubule defect and the development of giant lysosomes in CH cells was obtained. Thus, CH fibroblasts grown in vitro developed abnormal lysosomes in the majority of cells. However, the same cells cultured in the presence of cholinergic agonists developed a majority of lysosomes that were morphologically normal at the level of the light microscope. Similarly, granule morphology appeared normal in peripheral blood leukocytes from mice treated chronically in vivo with cholinergic agonists.
Publication Types:
Research Support, U.S. Gov't, P.H.S.
Review
PMID: 187062 [PubMed - indexed for MEDLINE]
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