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Gonzalez SJ, Heckel JM, Goldblum RR, Reid TA, McClellan M, Gardner MK. Rapid binding to protofilament edge sites facilitates tip tracking of EB1 at growing microtubule plus-ends. eLife 2024; 13:e91719. [PMID: 38385657 PMCID: PMC10883673 DOI: 10.7554/elife.91719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Accepted: 01/31/2024] [Indexed: 02/23/2024] Open
Abstract
EB1 is a key cellular protein that delivers regulatory molecules throughout the cell via the tip-tracking of growing microtubule plus-ends. Thus, it is important to understand the mechanism for how EB1 efficiently tracks growing microtubule plus-ends. It is widely accepted that EB1 binds with higher affinity to GTP-tubulin subunits at the growing microtubule tip, relative to GDP-tubulin along the microtubule length. However, it is unclear whether this difference in affinity alone is sufficient to explain the tip-tracking of EB1 at growing microtubule tips. Previously, we found that EB1 binds to exposed microtubule protofilament-edge sites at a ~70 fold faster rate than to closed-lattice sites, due to diffusional steric hindrance to binding. Thus, we asked whether rapid protofilament-edge binding could contribute to efficient EB1 tip tracking. A computational simulation with differential EB1 on-rates based on closed-lattice or protofilament-edge binding, and with EB1 off-rates that were dependent on the tubulin hydrolysis state, robustly recapitulated experimental EB1 tip tracking. To test this model, we used cell-free biophysical assays, as well as live-cell imaging, in combination with a Designed Ankyrin Repeat Protein (DARPin) that binds exclusively to protofilament-edge sites, and whose binding site partially overlaps with the EB1 binding site. We found that DARPin blocked EB1 protofilament-edge binding, which led to a decrease in EB1 tip tracking on dynamic microtubules. We conclude that rapid EB1 binding to microtubule protofilament-edge sites contributes to robust EB1 tip tracking at the growing microtubule plus-end.
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Affiliation(s)
- Samuel J Gonzalez
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, United States
| | - Julia M Heckel
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, United States
| | - Rebecca R Goldblum
- Department of Biophysics, Molecular Biology, and Biochemistry, University of Minnesota, Minneapolis, United States
- Medical Scientist Training Program, University of Minnesota, Minneapolis, United States
| | - Taylor A Reid
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, United States
| | - Mark McClellan
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, United States
| | - Melissa K Gardner
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, United States
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2
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Chiang DY, Verkerk AO, Victorio R, Shneyer BI, van der Vaart B, Jouni M, Narendran N, Kc A, Sampognaro JR, Vetrano-Olsen F, Oh JS, Buys E, de Jonge B, Shah DA, Kiviniemi T, Burridge PW, Bezzina CR, Akhmanova A, MacRae CA. The Role of MAPRE2 and Microtubules in Maintaining Normal Ventricular Conduction. Circ Res 2024; 134:46-59. [PMID: 38095085 DOI: 10.1161/circresaha.123.323231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 11/28/2023] [Indexed: 01/06/2024]
Abstract
BACKGROUND Brugada syndrome is associated with loss-of-function SCN5A variants, yet these account for only ≈20% of cases. A recent genome-wide association study identified a novel locus within MAPRE2, which encodes EB2 (microtubule end-binding protein 2), implicating microtubule involvement in Brugada syndrome. METHODS A mapre2 knockout zebrafish model was generated using CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/clustered regularly interspaced short palindromic repeat-associated protein 9) and validated by Western blot. Larval hearts at 5 days post-fertilization were isolated for voltage mapping and immunocytochemistry. Adult fish hearts were used for ECG, patch clamping, and immunocytochemistry. Morpholinos were injected into embryos at 1-cell stage for knockdown experiments. A transgenic zebrafish line with cdh2 tandem fluorescent timer was used to study adherens junctions. Microtubule plus-end tracking and patch clamping were performed in human induced pluripotent stem cell derived cardiomyocytes (iPSC-CMs) with MAPRE2 knockdown and knockout, respectively. RESULTS Voltage mapping of mapre2 knockout hearts showed a decrease in ventricular maximum upstroke velocity of the action potential and conduction velocity, suggesting loss of cardiac voltage-gated sodium channel function. ECG showed QRS prolongation in adult knockout fish, and patch clamping showed decreased sodium current density in knockout ventricular myocytes and arrhythmias in knockout iPSC-CMs. Confocal imaging showed disorganized adherens junctions and mislocalization of mature Ncad (N-cadherin) with mapre2 loss of function, associated with a decrease of detyrosinated tubulin. MAPRE2 knockdown in iPSC-CMs led to an increase in microtubule growth velocity and distance, indicating changes in microtubule dynamics. Finally, knockdown of ttl encoding tubulin tyrosine ligase in mapre2 knockout larvae rescued tubulin detyrosination and ventricular maximum upstroke velocity of the action potential. CONCLUSIONS Genetic ablation of mapre2 led to a decrease in voltage-gated sodium channel function, a hallmark of Brugada syndrome, associated with disruption of adherens junctions, decrease of detyrosinated tubulin as a marker of microtubule stability, and changes in microtubule dynamics. Restoration of the detyrosinated tubulin fraction with ttl knockdown led to rescue of voltage-gated sodium channel-related functional parameters in mapre2 knockout hearts. Taken together, our study implicates microtubule dynamics in the modulation of ventricular conduction.
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Affiliation(s)
- David Y Chiang
- Cardiovascular Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA (D.Y.C., R.V., N.N., A.K., J.R.S., F.V.-O., J.S.O., E.B., C.A.M.)
| | - Arie O Verkerk
- Department of Experimental Cardiology, Heart Center (A.O.V., C.R.B.), Academic Medical Center, Amsterdam UMC, the Netherlands
| | - Rachelle Victorio
- Cardiovascular Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA (D.Y.C., R.V., N.N., A.K., J.R.S., F.V.-O., J.S.O., E.B., C.A.M.)
| | - Boris I Shneyer
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, the Netherlands (B.I.S., B.v.d.V., A.A.)
| | - Babet van der Vaart
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, the Netherlands (B.I.S., B.v.d.V., A.A.)
| | - Mariam Jouni
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (M.J., D.A.S., P.W.B.)
| | - Nakul Narendran
- Cardiovascular Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA (D.Y.C., R.V., N.N., A.K., J.R.S., F.V.-O., J.S.O., E.B., C.A.M.)
| | - Ashmita Kc
- Cardiovascular Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA (D.Y.C., R.V., N.N., A.K., J.R.S., F.V.-O., J.S.O., E.B., C.A.M.)
| | - James R Sampognaro
- Cardiovascular Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA (D.Y.C., R.V., N.N., A.K., J.R.S., F.V.-O., J.S.O., E.B., C.A.M.)
| | - Franki Vetrano-Olsen
- Cardiovascular Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA (D.Y.C., R.V., N.N., A.K., J.R.S., F.V.-O., J.S.O., E.B., C.A.M.)
| | - John S Oh
- Cardiovascular Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA (D.Y.C., R.V., N.N., A.K., J.R.S., F.V.-O., J.S.O., E.B., C.A.M.)
| | - Eva Buys
- Cardiovascular Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA (D.Y.C., R.V., N.N., A.K., J.R.S., F.V.-O., J.S.O., E.B., C.A.M.)
| | - Berend de Jonge
- Department of Medical Biology (B.d.J.), Academic Medical Center, Amsterdam UMC, the Netherlands
| | - Disheet A Shah
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (M.J., D.A.S., P.W.B.)
| | - Tuomas Kiviniemi
- Heart Center, Turku University Hospital and University of Turku, Finland (T.K.)
| | - Paul W Burridge
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (M.J., D.A.S., P.W.B.)
| | - Connie R Bezzina
- Department of Experimental Cardiology, Heart Center (A.O.V., C.R.B.), Academic Medical Center, Amsterdam UMC, the Netherlands
| | - Anna Akhmanova
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, the Netherlands (B.I.S., B.v.d.V., A.A.)
| | - Calum A MacRae
- Cardiovascular Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA (D.Y.C., R.V., N.N., A.K., J.R.S., F.V.-O., J.S.O., E.B., C.A.M.)
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Farmer VJ, Zanic M. Beyond the GTP-cap: Elucidating the molecular mechanisms of microtubule catastrophe. Bioessays 2023; 45:e2200081. [PMID: 36398561 PMCID: PMC10648283 DOI: 10.1002/bies.202200081] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 11/03/2022] [Accepted: 11/04/2022] [Indexed: 11/19/2022]
Abstract
Almost 40 years since the discovery of microtubule dynamic instability, the molecular mechanisms underlying microtubule dynamics remain an area of intense research interest. The "standard model" of microtubule dynamics implicates a "cap" of GTP-bound tubulin dimers at the growing microtubule end as the main determinant of microtubule stability. Loss of the GTP-cap leads to microtubule "catastrophe," a switch-like transition from microtubule growth to shrinkage. However, recent studies, using biochemical in vitro reconstitution, cryo-EM, and computational modeling approaches, challenge the simple GTP-cap model. Instead, a new perspective on the mechanisms of microtubule dynamics is emerging. In this view, highly dynamic transitions between different structural conformations of the growing microtubule end - which may or may not be directly linked to the nucleotide content at the microtubule end - ultimately drive microtubule catastrophe.
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Affiliation(s)
- Veronica J. Farmer
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee, USA
| | - Marija Zanic
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee, USA
- Department of Biomolecular and Chemical Engineering, Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA
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4
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Benítez R, Núñez Y, Ayuso M, Isabel B, Fernández-Barroso MA, De Mercado E, Gómez-Izquierdo E, García-Casco JM, López-Bote C, Óvilo C. Changes in Biceps femoris Transcriptome along Growth in Iberian Pigs Fed Different Energy Sources and Comparative Analysis with Duroc Breed. Animals (Basel) 2021; 11:ani11123505. [PMID: 34944282 PMCID: PMC8697974 DOI: 10.3390/ani11123505] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 11/26/2021] [Accepted: 12/06/2021] [Indexed: 12/19/2022] Open
Abstract
Simple Summary The genetic mechanisms that regulate biological processes, such as skeletal muscle development and growth, or intramuscular fat deposition, have attracted great interest, given their impact on production traits and meat quality. In this sense, a comparison of the transcriptome of skeletal muscle between phenotypically different pig breeds, or along growth, could be useful to improve the understanding of the molecular processes underlying the differences in muscle metabolism and phenotypic traits, potentially driving the identification of causal genes, regulators and metabolic pathways involved in their variability. Abstract This experiment was conducted to investigate the effects of developmental stage, breed, and diet energy source on the genome-wide expression, meat quality traits, and tissue composition of biceps femoris muscle in growing pure Iberian and Duroc pigs. The study comprised 59 Iberian (IB) and 19 Duroc (DU) animals, who started the treatment at an average live weight (LW) of 19.9 kg. The animals were kept under identical management conditions and fed two diets with different energy sources (6% high oleic sunflower oil or carbohydrates). Twenty-nine IB animals were slaughtered after seven days of treatment at an average LW of 24.1 kg, and 30 IB animals plus all the DU animals were slaughtered after 47 days at an average LW of 50.7 kg. The main factors affecting the muscle transcriptome were age, with 1832 differentially expressed genes (DEGs), and breed (1055 DEGs), while the effect of diet on the transcriptome was very small. The results indicated transcriptome changes along time in Iberian animals, being especially related to growth and tissue development, extracellular matrix (ECM) composition, and cytoskeleton organization, with DEGs affecting relevant functions and biological pathways, such as myogenesis. The breed also affected functions related to muscle development and cytoskeleton organization, as well as functions related to solute transport and lipid and carbohydrate metabolism. Taking into account the results of the two main comparisons (age and breed effects), we can postulate that the Iberian breed is more precocious than the Duroc breed, regarding myogenesis and muscle development, in the studied growing stage.
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Affiliation(s)
- Rita Benítez
- Departamento de Mejora Genética Animal, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA-CSIC), 28040 Madrid, Spain; (R.B.); (Y.N.); (M.A.F.-B.); (J.M.G.-C.)
| | - Yolanda Núñez
- Departamento de Mejora Genética Animal, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA-CSIC), 28040 Madrid, Spain; (R.B.); (Y.N.); (M.A.F.-B.); (J.M.G.-C.)
| | - Miriam Ayuso
- Department of Veterinary Sciences, Faculty of Biomedical, Pharmaceutical and Veterinary Sciences, University of Antwerp, B-2610 Wilrijk, Belgium;
| | - Beatriz Isabel
- Departamento de Producción Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, 28040 Madrid, Spain; (B.I.); (C.L.-B.)
| | - Miguel A. Fernández-Barroso
- Departamento de Mejora Genética Animal, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA-CSIC), 28040 Madrid, Spain; (R.B.); (Y.N.); (M.A.F.-B.); (J.M.G.-C.)
| | - Eduardo De Mercado
- Centro de Pruebas de Porcino ITACYL, Hontalbilla, 40353 Segovia, Spain; (E.D.M.); (E.G.-I.)
| | - Emilio Gómez-Izquierdo
- Centro de Pruebas de Porcino ITACYL, Hontalbilla, 40353 Segovia, Spain; (E.D.M.); (E.G.-I.)
| | - Juan M. García-Casco
- Departamento de Mejora Genética Animal, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA-CSIC), 28040 Madrid, Spain; (R.B.); (Y.N.); (M.A.F.-B.); (J.M.G.-C.)
| | - Clemente López-Bote
- Departamento de Producción Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, 28040 Madrid, Spain; (B.I.); (C.L.-B.)
| | - Cristina Óvilo
- Departamento de Mejora Genética Animal, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA-CSIC), 28040 Madrid, Spain; (R.B.); (Y.N.); (M.A.F.-B.); (J.M.G.-C.)
- Correspondence: ; Tel.: +34-91-3471492
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Petrova DP, Khabudaev KV, Bedoshvili YD, Likhoshway YV. Phylogeny and structural peculiarities of the EB proteins of diatoms. J Struct Biol 2021; 213:107775. [PMID: 34364984 DOI: 10.1016/j.jsb.2021.107775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 08/02/2021] [Accepted: 08/03/2021] [Indexed: 11/25/2022]
Abstract
The end-binding proteins are a family of microtubule-associated proteins; this family belongs to plus-end-tracking proteins (+TIPs) that regulate microtubule growth and stabilisation. Although the genes encoding EB proteins are found in all eukaryotic genomes, most studies of them have centred on one or another taxonomic group, without a broad comparative analysis. Here, we present a first phylogenetic analysis and a comparative analysis of domain structures of diatom EB proteins in comparison with other phyla of Chromista, red and green algae, as well as model organisms A. thaliana and H. sapiens. Phylogenetically, diatom EB proteins are separated into six clades, generally corresponding to the phylogeny of their respective organisms. The domain structure of this family is highly variable, but the CH and EBH domains responsible for binding tubulin and other MAPs are mostly conserved. Homologous modelling of the F. cylindrus EB protein shows that conserved motifs of the CH domain are positioned on the protein surface, which is necessary for their functioning. We hypothesise that high variance of the diatom C-terminal domain is caused by previously unknown interactions with a CAP-GLY motif of dynactin subunit p150. Our findings contribute to wider possibilities for further investigations of the cytoskeleton in diatoms.
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Affiliation(s)
- Darya P Petrova
- Limnological Institute, Siberian Branch, Russian Academy of Sciences, Irkutsk, Russia
| | - Kirill V Khabudaev
- Limnological Institute, Siberian Branch, Russian Academy of Sciences, Irkutsk, Russia
| | | | - Yelena V Likhoshway
- Limnological Institute, Siberian Branch, Russian Academy of Sciences, Irkutsk, Russia.
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6
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Ustinov NB, Korshunova AV, Gudimchuk NB. Protein Complex NDC80: Properties, Functions, and Possible Role in Pathophysiology of Cell Division. BIOCHEMISTRY (MOSCOW) 2020; 85:448-462. [PMID: 32569552 DOI: 10.1134/s0006297920040057] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Mitotic division maintains genetic identity of any multicellular organism throughout an entire lifetime. Each time a parent cell divides, chromosomes are equally distributed between the daughter cells due to the action of mitotic spindle. Mitotic spindle is formed by the microtubules that represent dynamic polymers of tubulin protein. Spindle microtubules are attached end-on to kinetochores - large multi-protein complexes on chromosomes. This review focuses on the four-subunit NDC80 complex, one of the most important kinetochore elements that plays a major role in the attachment of assembling/disassembling microtubule ends to the chromosomes. Here, we summarize published data on the structure, properties, and regulation of the NDC80 complex and discuss possible relationship between changes in the expression of genes coding for the NDC80 complex components, mitotic disorders, and oncogenesis with special emphasis on the diagnostic and therapeutic potential of NDC80.
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Affiliation(s)
- N B Ustinov
- Center for Theoretical Problems of Physico-Chemical Pharmacology, Russian Academy of Sciences, Moscow, 119991, Russia
| | - A V Korshunova
- Center for Theoretical Problems of Physico-Chemical Pharmacology, Russian Academy of Sciences, Moscow, 119991, Russia.,Lomonosov Moscow State University, Faculty of Physics, Moscow, 119991, Russia
| | - N B Gudimchuk
- Center for Theoretical Problems of Physico-Chemical Pharmacology, Russian Academy of Sciences, Moscow, 119991, Russia. .,Lomonosov Moscow State University, Faculty of Physics, Moscow, 119991, Russia
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7
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Barbiero I, De Rosa R, Kilstrup-Nielsen C. Microtubules: A Key to Understand and Correct Neuronal Defects in CDKL5 Deficiency Disorder? Int J Mol Sci 2019; 20:E4075. [PMID: 31438497 PMCID: PMC6747382 DOI: 10.3390/ijms20174075] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 08/14/2019] [Accepted: 08/19/2019] [Indexed: 02/06/2023] Open
Abstract
CDKL5 deficiency disorder (CDD) is a severe neurodevelopmental encephalopathy caused by mutations in the X-linked CDKL5 gene that encodes a serine/threonine kinase. CDD is characterised by the early onset of seizures and impaired cognitive and motor skills. Loss of CDKL5 in vitro and in vivo affects neuronal morphology at early and late stages of maturation, suggesting a link between CDKL5 and the neuronal cytoskeleton. Recently, various microtubule (MT)-binding proteins have been identified as interactors of CDKL5, indicating that its roles converge on regulating MT functioning. MTs are dynamic structures that are important for neuronal morphology, migration and polarity. The delicate control of MT dynamics is fundamental for proper neuronal functions, as evidenced by the fact that aberrant MT dynamics are involved in various neurological disorders. In this review, we highlight the link between CDKL5 and MTs, discussing how CDKL5 deficiency may lead to deranged neuronal functions through aberrant MT dynamics. Finally, we discuss whether the regulation of MT dynamics through microtubule-targeting agents may represent a novel strategy for future pharmacological approaches in the CDD field.
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Affiliation(s)
- Isabella Barbiero
- Department of Biotechnology and Life Sciences, (DBSV), University of Insubria, Via Manara 7, 21052 Busto Arsizio (VA), Italy
| | - Roberta De Rosa
- Department of Biotechnology and Life Sciences, (DBSV), University of Insubria, Via Manara 7, 21052 Busto Arsizio (VA), Italy
| | - Charlotte Kilstrup-Nielsen
- Department of Biotechnology and Life Sciences, (DBSV), University of Insubria, Via Manara 7, 21052 Busto Arsizio (VA), Italy.
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8
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Mustyatsa VV, Kostarev AV, Tvorogova AV, Ataullakhanov FI, Gudimchuk NB, Vorobjev IA. Fine structure and dynamics of EB3 binding zones on microtubules in fibroblast cells. Mol Biol Cell 2019; 30:2105-2114. [PMID: 31141458 PMCID: PMC6743451 DOI: 10.1091/mbc.e18-11-0723] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 05/14/2019] [Accepted: 05/21/2019] [Indexed: 11/26/2022] Open
Abstract
End-binding (EB) proteins associate with the growing tips of microtubules (MTs)and modulate their dynamics directly and indirectly, by recruiting essential factors to fine-tune MTs for their many essential roles in cells. Previously EB proteins have been shown to recognize a stabilizing GTP/GDP-Pi cap at the tip of growing MTs, but information about additional EB-binding zones on MTs has been limited. In this work, we studied fluorescence intensity profiles of one of the three mammalian EB-proteins, EB3, fused with red fluorescent protein (RFP). The distribution of EB3 on MTs in mouse fibroblasts frequently deviated from single exponential decay and exhibited secondary peaks. Those secondary peaks, which we refer to as EB3-islands, were detected on 56% comets of growing MTs and were encountered once per 44 s of EB3-RFP comet growth time with about 5 s half-lifetime. The majority of EB3-islands in the vicinity of MT tips was stationary and originated from EB3 comets moving with the growing MT tips. Computational modeling of the decoration of dynamic MT tips by EB3 suggested that the EB3-islands could not be explained simply by a stochastic first-order GTP hydrolysis/phosphate release. We speculate that additional protein factors contribute to EB3 residence time on MTs in cells, likely affecting MT dynamics.
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Affiliation(s)
- V. V. Mustyatsa
- Lomonosov Moscow State University, 119991 Moscow, Russia
- Dmitry Rogachev National Research Center of Pediatric Hematology, Oncology and Immunology, 117198 Moscow, Russia
| | - A. V. Kostarev
- Lomonosov Moscow State University, 119991 Moscow, Russia
| | | | - F. I. Ataullakhanov
- Lomonosov Moscow State University, 119991 Moscow, Russia
- Dmitry Rogachev National Research Center of Pediatric Hematology, Oncology and Immunology, 117198 Moscow, Russia
- Center for Theoretical Problems of Physicochemical Pharmacology, Russian Academy of Sciences, 119334 Moscow, Russia
| | - N. B. Gudimchuk
- Lomonosov Moscow State University, 119991 Moscow, Russia
- Dmitry Rogachev National Research Center of Pediatric Hematology, Oncology and Immunology, 117198 Moscow, Russia
- Center for Theoretical Problems of Physicochemical Pharmacology, Russian Academy of Sciences, 119334 Moscow, Russia
| | - I. A. Vorobjev
- Lomonosov Moscow State University, 119991 Moscow, Russia
- Nazarbayev University, 010000 Nur-Sultan, Kazakhstan
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