1
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The human T-cell leukemia virus type-1 tax oncoprotein dissociates NF-κB p65 RelA-Stathmin complexes and causes catastrophic mitotic spindle damage and genomic instability. Virology 2019; 535:83-101. [PMID: 31299491 DOI: 10.1016/j.virol.2019.07.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 06/21/2019] [Accepted: 07/02/2019] [Indexed: 12/23/2022]
Abstract
Genomic instability is a hallmark of many cancers; however, the molecular etiology of chromosomal dysregulation is not well understood. The human T-cell leukemia virus type-1 (HTLV-1) oncoprotein Tax activates NF-κB-signaling and induces DNA-damage and aberrant chromosomal segregation through diverse mechanisms which contribute to viral carcinogenesis. Intriguingly, Stathmin/oncoprotein-18 (Op-18) depolymerizes tubulin and interacts with the p65RelA subunit and functions as a cofactor for NF-κB-dependent transactivation. We thus hypothesized that the dissociation of p65RelA-Stathmin/Op-18 complexes by Tax could lead to the catastrophic destabilization of microtubule (MT) spindle fibers during mitosis and provide a novel mechanistic link between NF-κB-signaling and genomic instability. Here we report that the inhibition of Stathmin expression by the retroviral latency protein, p30II, or knockdown with siRNA-stathmin, dampens Tax-mediated NF-κB transactivation and counters Tax-induced genomic instability and cytotoxicity. The Tax-G148V mutant, defective for NF-κB activation, exhibited reduced p65RelA-Stathmin binding and diminished genomic instability and cytotoxicity. Dominant-negative inhibitors of NF-κB also prevented Tax-induced multinucleation and apoptosis. Moreover, cell clones containing the infectious HTLV-1 ACH. p30II mutant provirus, impaired for p30II production, exhibited increased multinucleation and the accumulation of cytoplasmic tubulin aggregates following nocodozole-treatment. These findings allude to a mechanism whereby NF-κB-signaling regulates tubulin dynamics and mitotic instability through the modulation of p65RelA-Stathmin/Op-18 interactions, and support the notion that p30II enhances the survival of Tax-expressing HTLV-1-transformed cells.
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2
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Lu NT, Liu NM, Patel D, Vu JQ, Liu L, Kim CY, Cho P, Khachatoorian R, Patel N, Magyar CE, Ganapathy E, Arumugaswami V, Dasgupta A, French SW. Oncoprotein Stathmin Modulates Sensitivity to Apoptosis in Hepatocellular Carcinoma Cells During Hepatitis C Viral Replication. J Cell Death 2018; 11:1179066018785141. [PMID: 30034249 PMCID: PMC6047100 DOI: 10.1177/1179066018785141] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 05/28/2018] [Indexed: 01/28/2023] Open
Abstract
Patients with chronic hepatitis C virus (HCV) infection risk complications of
cirrhosis, liver failure, and hepatocellular carcinoma (HCC). Previously, our
proteomic examination of hepatocytes carrying a HCV-replicon revealed that
deregulation of cytoskeletal dynamics may be a potential mechanism of
viral-induced HCC growth. Here, we demonstrate the effect of HCV replication on
the microtubule regulator stathmin (STMN1) in HCC cells. We further explore how
the altered activity or synthesis of stathmin affects cellular proliferation and
sensitivity to apoptosis in control HCC cells (Huh7.5) and experimental
HCV-replicon harboring HCC cells (R-Huh7.5). The HCV-replicon harboring HCC
cells (R-Huh 7.5) lack viral structural genes/proteins for acute infectivity and
thus is the standard model for in vitro chronic infection study. Knockdown of
endogenous stathmin reduced sensitivity to apoptosis in replicon cells.
Meanwhile, constitutively active stathmin increased sensitivity to apoptosis in
replicon cells. In addition, overexpression of constitutively active stathmin
reduced cell proliferation in both control and replicon cells. These findings
implicate, for the first time, a novel role for stathmin in viral
replication–related apoptosis. Stathmin’s potential role in HCV replication and
HCC make it a candidate for the future study of viral-induced malignancies.
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Affiliation(s)
- Nu T Lu
- Department of Pathology & Laboratory Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA, USA.,Department of Hematology and Oncology, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
| | - Natalie M Liu
- Department of Pathology & Laboratory Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
| | - Darshil Patel
- Department of Pathology & Laboratory Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
| | - James Q Vu
- Department of Pathology & Laboratory Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
| | - Lisa Liu
- Department of Pathology & Laboratory Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
| | - Chae Yeon Kim
- Department of Pathology & Laboratory Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
| | - Peter Cho
- Department of Pathology & Laboratory Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
| | - Ronik Khachatoorian
- Department of Pathology & Laboratory Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
| | - Nikita Patel
- Department of Pathology & Laboratory Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
| | - Clara E Magyar
- Department of Pathology & Laboratory Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
| | - Ekambaram Ganapathy
- Department of Pathology & Laboratory Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
| | - Vaithilingaraja Arumugaswami
- Department of Surgery, David Geffen School of Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA, USA.,Department of Surgery and Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Asim Dasgupta
- Department of Microbiology, Immunology & Molecular Genetics, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
| | - Samuel Wheeler French
- Department of Pathology & Laboratory Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA, USA.,UCLA Jonsson Comprehensive Cancer Center, Los Angeles, CA, USA
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3
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How Do Microtubule Dynamics Relate to the Hallmarks of Learning and Memory? J Neurosci 2018; 36:5911-3. [PMID: 27251613 DOI: 10.1523/jneurosci.0920-16.2016] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2016] [Accepted: 04/26/2016] [Indexed: 11/21/2022] Open
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4
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Kapoor TM. Metaphase Spindle Assembly. BIOLOGY 2017; 6:biology6010008. [PMID: 28165376 PMCID: PMC5372001 DOI: 10.3390/biology6010008] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 01/17/2017] [Accepted: 01/19/2017] [Indexed: 01/31/2023]
Abstract
A microtubule-based bipolar spindle is required for error-free chromosome segregation during cell division. In this review I discuss the molecular mechanisms required for the assembly of this dynamic micrometer-scale structure in animal cells.
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Affiliation(s)
- Tarun M Kapoor
- Laboratory of Chemistry and Cell Biology, the Rockefeller University, New York, NY 10065, USA.
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5
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Genetic Demonstration of a Role for Stathmin in Adult Hippocampal Neurogenesis, Spinogenesis, and NMDA Receptor-Dependent Memory. J Neurosci 2016; 36:1185-202. [PMID: 26818507 DOI: 10.1523/jneurosci.4541-14.2016] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
UNLABELLED Neurogenesis and memory formation are essential features of the dentate gyrus (DG) area of the hippocampus, but to what extent the mechanisms responsible for both processes overlap remains poorly understood. Stathmin protein, whose tubulin-binding and microtubule-destabilizing activity is negatively regulated by its phosphorylation, is prominently expressed in the DG. We show here that stathmin is involved in neurogenesis, spinogenesis, and memory formation in the DG. tTA/tetO-regulated bitransgenic mice, expressing the unphosphorylatable constitutively active Stathmin4A mutant (Stat4A), exhibit impaired adult hippocampal neurogenesis and reduced spine density in the DG granule neurons. Although Stat4A mice display deficient NMDA receptor-dependent memory in contextual discrimination learning, which is dependent on hippocampal neurogenesis, their NMDA receptor-independent memory is normal. Confirming NMDA receptor involvement in the memory deficits, Stat4A mutant mice have a decrease in the level of synaptic NMDA receptors and a reduction in learning-dependent CREB-mediated gene transcription. The deficits in neurogenesis, spinogenesis, and memory in Stat4A mice are not present in mice in which tTA/tetO-dependent transgene transcription is blocked by doxycycline through their life. The memory deficits are also rescued within 3 d by intrahippocampal infusion of doxycycline, further indicating a role for stathmin expressed in the DG in contextual memory. Our findings therefore point to stathmin and microtubules as a mechanistic link between neurogenesis, spinogenesis, and NMDA receptor-dependent memory formation in the DG. SIGNIFICANCE STATEMENT In the present study, we aimed to clarify the role of stathmin in neuronal and behavioral functions. We characterized the neurogenic, behavioral, and molecular consequences of the gain-of-function stathmin mutation using a bitransgenic mouse expressing a constitutively active form of stathmin. We found that stathmin plays an important role in adult hippocampal neurogenesis and spinogenesis. In addition, stathmin mutation led to impaired NMDA receptor-dependent and neurogenesis-associated memory and did not affect NMDA receptor-independent memory. Moreover, biochemical analysis suggested that stathmin regulates the synaptic transport of NMDA receptors, which in turn influence CREB-mediated gene transcription machinery. Overall, these data suggest that stathmin is an important molecule for neurogenesis, spinogenesis, and NMDA receptor-dependent learning and memory.
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6
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Uchida S, Martel G, Pavlowsky A, Takizawa S, Hevi C, Watanabe Y, Kandel ER, Alarcon JM, Shumyatsky GP. Learning-induced and stathmin-dependent changes in microtubule stability are critical for memory and disrupted in ageing. Nat Commun 2014; 5:4389. [PMID: 25007915 PMCID: PMC4137320 DOI: 10.1038/ncomms5389] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Accepted: 06/13/2014] [Indexed: 01/09/2023] Open
Abstract
Changes in the stability of microtubules regulate many biological processes, but their role in memory remains unclear. Here we show that learning causes biphasic changes in the microtubule-associated network in the hippocampus. In the early phase, stathmin is dephosphorylated, enhancing its microtubule-destabilizing activity by promoting stathmin-tubulin binding, whereas in the late phase these processes are reversed leading to an increase in microtubule/KIF5-mediated localization of the GluA2 subunit of AMPA receptors at synaptic sites. A microtubule stabilizer paclitaxel decreases or increases memory when applied at the early or late phases, respectively. Stathmin mutations disrupt changes in microtubule stability, GluA2 localization, synaptic plasticity and memory. Aged wild-type mice show impairments in stathmin levels, changes in microtubule stability, and GluA2 localization. Blocking GluA2 endocytosis rescues memory deficits in stathmin mutant and aged wild-type mice. These findings demonstrate a role for microtubules in memory in young adult and aged individuals.
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Affiliation(s)
- Shusaku Uchida
- 1] Department of Genetics, Rutgers University, Room 322 Life Sciences Building,145 Bevier Road, Piscataway, New Jersey 08854, USA [2] Division of Neuropsychiatry, Department of Neuroscience, Yamaguchi University Graduate School of Medicine, 1-1-1 Minami-Kogushi, Ube, Yamaguchi 755-8505, Japan [3]
| | - Guillaume Martel
- 1] Department of Genetics, Rutgers University, Room 322 Life Sciences Building,145 Bevier Road, Piscataway, New Jersey 08854, USA [2]
| | - Alice Pavlowsky
- Department of Pathology, State University of New York, Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, New York 11203, USA
| | - Shuichi Takizawa
- Department of Genetics, Rutgers University, Room 322 Life Sciences Building,145 Bevier Road, Piscataway, New Jersey 08854, USA
| | - Charles Hevi
- Department of Genetics, Rutgers University, Room 322 Life Sciences Building,145 Bevier Road, Piscataway, New Jersey 08854, USA
| | - Yoshifumi Watanabe
- Division of Neuropsychiatry, Department of Neuroscience, Yamaguchi University Graduate School of Medicine, 1-1-1 Minami-Kogushi, Ube, Yamaguchi 755-8505, Japan
| | - Eric R Kandel
- Department of Neuroscience, Columbia University, Howard Hughes Medical Institute, Kavli Institute for Brain Science, 1051 Riverside Drive, New York, New York 10032, USA
| | - Juan Marcos Alarcon
- Department of Pathology, State University of New York, Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, New York 11203, USA
| | - Gleb P Shumyatsky
- Department of Genetics, Rutgers University, Room 322 Life Sciences Building,145 Bevier Road, Piscataway, New Jersey 08854, USA
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7
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Missimer JH, Steinmetz MO, van Gunsteren WF, Dolenc J. Influence of 63Ser phosphorylation and dephosphorylation on the structure of the stathmin helical nucleation sequence: a molecular dynamics study. Biochemistry 2012; 51:8455-63. [PMID: 22978582 DOI: 10.1021/bi300885y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Phosphorylation is an important mechanism regulating protein-protein interactions involving intrinsically disordered protein regions. Stathmin, an archetypical example of an intrinsically disordered protein, is a key regulator of microtubule dynamics in which phosphorylation of 63Ser within the helical nucleation sequence strongly down-regulates the tubulin binding and microtubule destabilizing activities of the protein. Experimental studies on a peptide encompassing the 19-residue helical nucleation sequence of stathmin (residues 55-73) indicate that phosphorylation of 63Ser destabilizes the peptide's secondary structure by disrupting the salt bridges supporting its helical conformation. In order to investigate this hypothesis at atomic resolution, we performed molecular dynamics simulations of nonphosphorylated and phosphorylated stathmin-[55-73] at room temperature and pressure, neutral pH, and explicit solvation using the recently released GROMOS force field 54A7. In the simulations of nonphosphorylated stathmin-[55-73] emerged salt bridges associated with helical configurations. In the simulations of 63Ser phosphorylated stathmin-[55-73] these configurations dispersed and were replaced by a proliferation of salt bridges yielding disordered configurations. The transformation of the salt bridges was accompanied by emergence of numerous interactions between main and side chains, involving notably the oxygen atoms of the phosphorylated 63Ser. The loss of helical structure induced by phosphorylation is reversible, however, as a final simulation showed. The results extend the hypothesis of salt bridge derangement suggested by experimental observations of the stathmin nucleation sequence, providing new insights into regulation of intrinsically disordered protein systems mediated by phosphorylation.
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Affiliation(s)
- John H Missimer
- Biomolecular Research, Paul Scherrer Institute, 5232 Villigen, Switzerland
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8
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Mullen MP, Elia G, Hilliard M, Parr MH, Diskin MG, Evans ACO, Crowe MA. Proteomic characterization of histotroph during the preimplantation phase of the estrous cycle in cattle. J Proteome Res 2012; 11:3004-18. [PMID: 22463384 DOI: 10.1021/pr300144q] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Uterine secretions, or histotroph, are a critical component for early embryo survival, functioning as the sole supply of vitamins, minerals, enzymes, and other myriad of nutrients required by the developing conceptus before implantation. Histotroph is therefore a promising source for biomarkers of uterine function and for enhancing our understanding of the environment supporting early embryo development and survival. Utilizing label-free liquid chromatography-tandem mass spectrometry (LC-MS/MS) shotgun proteomics, we characterized the uterine proteome at two key preimplantation stages of the estrous cycle in high fertility cattle. We identified 300 proteins on Day 7 and 510 proteins on Day 13 including 281 proteins shared between days. Five proteins were more abundant (P < 0.05) on Day 7 compared with Day 13 and included novel histotroph proteins cytokeratin 10 and stathmin. Twenty-nine proteins were more abundant (P < 0.05) including 13 unique on Day 13 compared with Day 7 and included previously identified legumain, metalloprotease inhibitor-2, and novel histotroph proteins chromogranin A and pyridoxal kinase. Functional analysis of the 34 differentially expressed proteins (including 14 novel to histotroph) revealed distinct biological roles putatively involved in early pregnancy, including remodelling of the uterine environment in preparation for implantation; nutrient metabolism; embryo growth, development and protection; maintenance of uterine health; and maternal immune modulation. This study is the first reported LC-MS/MS based global proteomic characterization of the uterine environment in any domesticated species before implantation and provides novel information on the temporal alterations in histotroph composition during critical stages for early embryo development and uterine function during the early establishment of pregnancy.
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Affiliation(s)
- Michael P Mullen
- Animal and Bioscience Research Department, Animal & Grassland Research and Innovation Centre, Teagasc, Mellows Campus, Athenry, Co. Galway, Ireland.
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9
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Manna T, Thrower DA, Honnappa S, Steinmetz MO, Wilson L. Regulation of microtubule dynamic instability in vitro by differentially phosphorylated stathmin. J Biol Chem 2009; 284:15640-9. [PMID: 19359244 PMCID: PMC2708860 DOI: 10.1074/jbc.m900343200] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2009] [Revised: 03/18/2009] [Indexed: 11/06/2022] Open
Abstract
Stathmin is an important regulator of microtubule polymerization and dynamics. When unphosphorylated it destabilizes microtubules in two ways, by reducing the microtubule polymer mass through sequestration of soluble tubulin into an assembly-incompetent T2S complex (two alpha:beta tubulin dimers per molecule of stathmin), and by increasing the switching frequency (catastrophe frequency) from growth to shortening at plus and minus ends by binding directly to the microtubules. Phosphorylation of stathmin on one or more of its four serine residues (Ser(16), Ser(25), Ser(38), and Ser(63)) reduces its microtubule-destabilizing activity. However, the effects of phosphorylation of the individual serine residues of stathmin on microtubule dynamic instability have not been investigated systematically. Here we analyzed the effects of stathmin singly phosphorylated at Ser(16) or Ser(63), and doubly phosphorylated at Ser(25) and Ser(38), on its ability to modulate microtubule dynamic instability at steady-state in vitro. Phosphorylation at either Ser(16) or Ser(63) strongly reduced or abolished the ability of stathmin to bind to and sequester soluble tubulin and its ability to act as a catastrophe factor by directly binding to the microtubules. In contrast, double phosphorylation of Ser(25) and Ser(38) did not affect the binding of stathmin to tubulin or microtubules or its catastrophe-promoting activity. Our results indicate that the effects of stathmin on dynamic instability are strongly but differently attenuated by phosphorylation at Ser(16) and Ser(63) and support the hypothesis that selective targeting by Ser(16)-specific or Ser(63)-specific kinases provides complimentary mechanisms for regulating microtubule function.
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Affiliation(s)
- Tapas Manna
- From the Department of Molecular, Cellular, and Developmental Biology and the Neuroscience Research Institute, University of California, Santa Barbara, California 93106 and
| | - Douglas A. Thrower
- From the Department of Molecular, Cellular, and Developmental Biology and the Neuroscience Research Institute, University of California, Santa Barbara, California 93106 and
| | - Srinivas Honnappa
- Biomolecular Research, Structural Biology, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - Michel O. Steinmetz
- Biomolecular Research, Structural Biology, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - Leslie Wilson
- From the Department of Molecular, Cellular, and Developmental Biology and the Neuroscience Research Institute, University of California, Santa Barbara, California 93106 and
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10
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Steinmetz MO. Structure and thermodynamics of the tubulin-stathmin interaction. J Struct Biol 2006; 158:137-47. [PMID: 17029844 DOI: 10.1016/j.jsb.2006.07.018] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2006] [Accepted: 07/10/2006] [Indexed: 10/24/2022]
Abstract
Oncoprotein 18/stathmin (stathmin) is a phosphorylation-controlled key regulator of microtubule dynamics. In recent years, substantial efforts were undertaken to characterize the complex formed between tubulin and the intrinsically disordered stathmin molecule. Here, I summarize and illustrate the current structural and thermodynamic studies on the tubulin-stathmin interaction. Based on these and on functional information I formulate an updated molecular mechanism on how tubulin-binding by stathmin regulates microtubule dynamics.
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Affiliation(s)
- Michel O Steinmetz
- Biomolecular Research, Structural Biology, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
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11
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Honnappa S, Jahnke W, Seelig J, Steinmetz MO. Control of intrinsically disordered stathmin by multisite phosphorylation. J Biol Chem 2006; 281:16078-83. [PMID: 16554300 DOI: 10.1074/jbc.m513524200] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Stathmin is an intrinsically disordered protein implicated in the regulation of microtubule dynamics and in the development of cancer. The microtubule destabilizing activity of stathmin is down-regulated by phosphorylation of four serine residues, Ser16, Ser25, Ser38, and Ser63. Here we have used calorimetric and spectroscopic methods, including nuclear magnetic resonance to analyze the properties of seven stathmin phosphoisoforms to bind tubulin and inhibit microtubule formation. We found that stathmin phosphorylation results in a substantial loss in hydration entropy upon tubulin-stathmin complex formation. Remarkably, a linear correlation between the free energy change of complex formation and the microtubule inhibition activities of stathmin phosphoisoforms was observed. This finding provides a biophysical basis for understanding the mechanism by which local stathmin activity gradients important for promoting localized microtubule growth are established. We further found that phosphorylation of Ser16 and Ser63 disrupts the formation of a tubulin-interacting beta-hairpin and a helical segment, respectively, explaining the dominant role of these residues in regulating cell cycle progression. The insight into the tubulin-stathmin interaction offers a molecular basis for understanding the nature and the factors that control intrinsically disordered protein systems in general.
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Affiliation(s)
- Srinivas Honnappa
- Biomolecular Research, Structural Biology, Paul Scherrer Insititut, CH-5232 Villigen PSI, Switzerland
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12
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Manna T, Thrower D, Miller HP, Curmi P, Wilson L. Stathmin Strongly Increases the Minus End Catastrophe Frequency and Induces Rapid Treadmilling of Bovine Brain Microtubules at Steady State in Vitro. J Biol Chem 2006; 281:2071-8. [PMID: 16317007 DOI: 10.1074/jbc.m510661200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Stathmin is a ubiquitous microtubule destabilizing protein that is believed to play an important role linking cell signaling to the regulation of microtubule dynamics. Here we show that stathmin strongly destabilizes microtubule minus ends in vitro at steady state, conditions in which the soluble tubulin and microtubule levels remain constant. Stathmin increased the minus end catastrophe frequency approximately 13-fold at a stathmin:tubulin molar ratio of 1:5. Stathmin steady-state catastrophe-promoting activity was considerably stronger at the minus ends than at the plus ends. Consistent with its ability to destabilize minus ends, stathmin strongly increased the treadmilling rate of bovine brain microtubules. By immunofluorescence microscopy, we also found that stathmin binds to purified microtubules along their lengths in vitro. Co-sedimentation of purified microtubules polymerized in the presence of a 1:5 initial molar ratio of stathmin to tubulin yielded a binding stoichiometry of 1 mol of stathmin per approximately 14.7 mol of tubulin in the microtubules. The results firmly establish that stathmin can increase the steady-state catastrophe frequency by a direct action on microtubules, and furthermore, they indicate that an important regulatory action of stathmin in cells may be to destabilize microtubule minus ends.
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Affiliation(s)
- Tapas Manna
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, CA 93106, USA
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13
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Niethammer P, Bastiaens P, Karsenti E. Stathmin-tubulin interaction gradients in motile and mitotic cells. Science 2004; 303:1862-6. [PMID: 15031504 DOI: 10.1126/science.1094108] [Citation(s) in RCA: 168] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The spatial organization of the microtubule cytoskeleton is thought to be directed by steady-state activity gradients of diffusible regulatory molecules. We visualized such intracellular gradients by monitoring the interaction between tubulin and a regulator of microtubule dynamics, stathmin, using a fluorescence resonance energy transfer (FRET) biosensor. These gradients were observed both during interphase in motile membrane protrusions and during mitosis around chromosomes, which suggests that a similar mechanism may contribute to the creation of polarized microtubule structures. These interaction patterns are likely to reflect phosphorylation of stathmin in these areas.
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Affiliation(s)
- Philipp Niethammer
- European Molecular Biology Laboratory, EMBL, Meyerhofstrasse 1, D-69117 Heidelberg, Germany
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14
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Abstract
Although the centrosome was first described over 100 years ago, we still know relatively little of the molecular mechanisms responsible for its functions. Recently, members of a novel family of centrosomal proteins have been identified in a wide variety of organisms. The transforming acidic coiled-coil-containing (TACC) proteins all appear to play important roles in cell division and cellular organisation in both embryonic and somatic systems. These closely related molecules have been implicated in microtubule stabilisation, acentrosomal spindle assembly, translational regulation, haematopoietic development and cancer progression. In this review, I summarise what we already know of this protein family and will use the TACC proteins to illustrate the many facets that centrosomes have developed during the course of evolution.
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Affiliation(s)
- Fanni Gergely
- Wellcome CR UK Institute, Department of Pharmacology, University of Cambridge, UK.
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15
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Misek DE, Chang CL, Kuick R, Hinderer R, Giordano TJ, Beer DG, Hanash SM. Transforming properties of a Q18-->E mutation of the microtubule regulator Op18. Cancer Cell 2002; 2:217-28. [PMID: 12242154 DOI: 10.1016/s1535-6108(02)00124-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
We have identified a somatic mutation in Op18 in a human esophageal adenocarcinoma. The mutant form of Op18 (M-Op18) was cloned and sequenced, revealing a substitution of a G for C at nucleotide 155, which results in a Q18-->E substitution in the protein. M-Op18 cDNA was expressed in NIH/3T3 cells, which resulted in foci formation and tumor growth in immunodeficient mice. Cell cycle analysis of M-Op18-expressing cells revealed a doubling in the percentage of cells in G2/M relative to cells overexpressing wild-type Op18, a decrease in M-Op18-specific phosphorylation, and alterations in tubulin ultrastructure in M-Op18-expressing cells. These results suggest that the somatic mutation identified in Op18 has profound effects on cell homeostasis that may lead to tumorigenicity.
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Affiliation(s)
- David E Misek
- Department of Pediatrics, University of Michigan, Ann Arbor, MI 48109, USA.
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16
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Amayed P, Pantaloni D, Carlier MF. The effect of stathmin phosphorylation on microtubule assembly depends on tubulin critical concentration. J Biol Chem 2002; 277:22718-24. [PMID: 11956188 DOI: 10.1074/jbc.m111605200] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Stathmin is a phosphorylation-regulated tubulin-binding protein. In vitro and in vivo studies using nonphosphorylatable and pseudophosphorylated mutants of stathmin have questioned the view that stathmin might act only as a tubulin-sequestering factor. Stathmin was proposed to effectively regulate microtubule dynamic instability by increasing the frequency of catastrophe (the transition from steady growth to rapid depolymerization), without interacting with tubulin. We have used a noninvasive method to measure the equilibrium dissociation constants of the T(2)S complexes of tubulin with stathmin, pseudophosphorylated (4E)-stathmin, and diphosphostathmin. At both pH 6.8 and pH 7.4, the relative sequestering efficiency of the different stathmin variants depends on the concentration of free tubulin, i.e. on the dynamic state of microtubules. This control is exerted in a narrow range of tubulin concentration due to the highly cooperative binding of tubulin to stathmin. Changes in pH affect the stability of tubulin-stathmin complexes but do not change stathmin function. The 4E-stathmin mutant mimics inactive phosphorylated stathmin at low tubulin concentration and sequesters tubulin almost as efficiently as stathmin at higher tubulin concentration. We propose that stathmin acts solely by sequestering tubulin, without affecting microtubule dynamics, and that the effect of stathmin phosphorylation on microtubule assembly depends on tubulin critical concentration.
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Affiliation(s)
- Phedra Amayed
- Dynamique du Cytosquelette, Laboratoire d'Enzymologie et Biochimie Structurales, CNRS, 91198 Gif-sur-Yvette, France
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Abstract
The past several years have seen major advances in our understanding of the mechanisms of microtubule destabilization by oncoprotein18/stathmin (Op18/stathmin) and related proteins. New structural information has clearly shown how members of the Op18/stathmin protein family bind tubulin dimers and suggests models for how these proteins stimulate catastrophe, the transition from microtubule growth to shortening. Regulation of Op18/stathmin by phosphorylation continues to capture much attention. Studies suggest that phosphorylation occurs in a localized fashion, resulting in decreased microtubule destabilizing activity near chromatin or microtubule polymer. A spatial gradient of inactive Op18/stathmin associated with chromatin or microtubules could contribute significantly to mitotic spindle assembly.
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Affiliation(s)
- Lynne Cassimeris
- Department of Biological Sciences, 111 Research Drive, Lehigh University, Bethlehem, PA18015, USA.
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18
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Abstract
Centrosomes of animal cells and spindle pole bodies of fungi are the major microtubule nucleating centers. Recent studies indicate that their capacity to organize microtubule arrays rests on elaborate control of the anchoring and release of the nucleated microtubules. Although common molecular mechanisms are likely to be involved in both cases, the centrosome from animal cells shows considerable complexity and flexibility, which contrasts with the simple laminar organization of spindle pole bodies in fungi. The role of the centriole pair in controlling both the structural stability and the activity of the centrosome in animal cells is now becoming clearer. The potential use of the generational asymmetry of centrosomes or spindle pole bodies for controlling cell polarity is also a growing theme.
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Affiliation(s)
- Michel Bornens
- Institut Curie, Section Recherche, UMR144 du Centre National de la Recherche Scientifique, 26 rue d'Ulm, 75248, Cedex 05, Paris, France.
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