scholarly journals 2-(m-Azidobenzoyl)taxol binds differentially to distinct β-tubulin isotypes

2016 ◽  
Vol 113 (40) ◽  
pp. 11294-11299 ◽  
Author(s):  
Chia-Ping Huang Yang ◽  
Eng-Hui Yap ◽  
Hui Xiao ◽  
Andras Fiser ◽  
Susan Band Horwitz
Keyword(s):  
Mammalian Cells ◽  
Bovine Brain ◽  
Drug Binding ◽  
Dynamic Simulations ◽  
Altered Expression ◽  
Stabilizing Agents ◽  
Tubulin Isotypes ◽  
Tubulin Isotype ◽  
Different Sources ◽  
Β Tubulin

There are seven β-tubulin isotypes present in distinct quantities in mammalian cells of different origin. Altered expression of β-tubulin isotypes has been reported in cancer cell lines resistant to microtubule stabilizing agents (MSAs) and in human tumors resistant to Taxol. To study the relative binding affinities of MSAs, tubulin from different sources, with distinct β-tubulin isotype content, were specifically photolabeled with a tritium-labeled Taxol analog, 2-(m-azidobenzoyl)taxol, alone or in the presence of MSAs. The inhibitory effects elicited by these MSAs on photolabeling were distinct for β-tubulin from different sources. To determine the exact amount of drug that binds to different β-tubulin isotypes, bovine brain tubulin was photolabeled and the isotypes resolved by high-resolution isoelectrofocusing. All bands were analyzed by mass spectrometry following cyanogen bromide digestion, and the identity and relative quantity of each β-tubulin isotype determined. It was found that compared with other β-tubulin isotypes, βIII-tubulin bound the least amount of 2-(m-azidobenzoyl)taxol. Analysis of the sequences of β-tubulin near the Taxol binding site indicated that, in addition to the M-loop that is known to be involved in drug binding, the leucine cluster region of βIII-tubulin contains a unique residue, alanine, at 218, compared with other isotypes that contain threonine. Molecular dynamic simulations indicated that the frequency of Taxol-accommodating conformations decreased dramatically in the T218A variant, compared with other β-tubulins. Our results indicate that the difference in residue 218 in βIII-tubulin may be responsible for inhibition of drug binding to this isotype, which could influence downstream cellular events.

scholarly journals The Caenorhabditis elegans Microtubule-severing Complex MEI-1/MEI-2 Katanin Interacts Differently with Two Superficially Redundant β-Tubulin Isotypes

2004 ◽  
Vol 15 (1) ◽  
pp. 142-150 ◽  
Author(s):  
Chenggang Lu ◽  
Martin Srayko ◽  
Paul E. Mains
Keyword(s):  
Caenorhabditis Elegans ◽  
Genetic Background ◽  
Morphological Changes ◽  
Meiotic Spindle ◽  
Tubulin Isotypes ◽  
Microtubule Severing ◽  
Tubulin Isotype ◽  
Embryonic Viability ◽  
Β Tubulin

The microtubule-severing protein complex katanin is required for a variety of important microtubule-base morphological changes in both animals and plants. Caenorhabditis elegans katanin is encoded by the mei-1 and mei-2 genes and is required for oocyte meiotic spindle formation and must be inactivated before the first mitotic cleavage. We identified a mutation, sb26, in the tbb-2 β-tubulin gene that partially inhibits MEI-1/MEI-2 activity: sb26 rescues lethality caused by ectopic MEI-1/MEI-2 expression during mitosis, and sb26 increases meiotic defects in a genetic background where MEI-1/MEI-2 activity is lower than normal. sb26 does not interfere with MEI-1/MEI-2 microtubule localization, suggesting that this mutation likely interferes with severing. Tubulin deletion alleles and RNA-mediated interference revealed that TBB-2 and the other germline enriched β-tubulin isotype, TBB-1, are redundant for embryonic viability. However, limiting MEI-1/MEI-2 activity in these experiments revealed that MEI-1/MEI-2 preferentially interacts with TBB-2–containing microtubules. Our results demonstrate that these two superficially redundant β-tubulin isotypes have functionally distinct roles in vivo.

scholarly journals Generation of antisera that discriminate among mammalian alpha-tubulins: introduction of specialized isotypes into cultured cells results in their coassembly without disruption of normal microtubule function.

1988 ◽  
Vol 106 (6) ◽  
pp. 2011-2022 ◽  
Author(s):  
W Gu ◽  
S A Lewis ◽  
N J Cowan
Keyword(s):  
Immune Response ◽  
Fusion Proteins ◽  
Mammalian Cells ◽  
Cultured Cells ◽  
Alpha Tubulin ◽  
Tubulin Isotypes ◽  
Tubulin Isotype ◽  
Carboxy Terminal ◽  
Nih 3T3 ◽  
Shared Epitopes

To assay the functional significance of the multiple but closely related alpha-tubulin polypeptides that are expressed in mammalian cells, we generated three specific immune sera, each of which uniquely recognizes a distinct alpha-tubulin isotype. All three isotypes are expressed in a tissue-restricted manner: one (M alpha 3/7) only in mature testis, one (M alpha 4) mainly in muscle and brain, and the third (M alpha 6) in several tissues at a very low level. A fourth specific antiserum was also generated that distinguishes between the tyrosinated and nontyrosinated form of a single alpha-tubulin isotype. Because individual tubulin isotypes cannot be purified biochemically, these sera were raised using cloned fusion proteins purified from host Escherichia coli cells. To suppress the immune response to shared epitopes, animals were first rendered tolerant to fusion proteins encoding all but one of the known mammalian alpha-tubulin isotypes. Subsequent challenge with the remaining fusion protein then resulted in the elicitation of an immune response to unique epitopes. Three criteria were used to establish the specificity of the resulting sera: (a) their ability to discriminate among cloned fusion proteins representing all the known mammalian alpha-tubulin isotypes; (b) their ability to uniquely detect alpha-tubulin in whole extracts of tissues; and (c) their capacity to stain microtubules in fixed preparations of cells transfected with sequences encoding the corresponding isotype. The transfection experiments served to demonstrate (a) the coassembly of M alpha 3/7, M alpha 4, and M alpha 6 into both interphase and spindle microtubules in HeLa cells and NIH 3T3 cells, and (b) that the M alpha 4 isotype, which is unique among mammalian alpha-tubulins in that it lacks an encoded carboxy-terminal tyrosine residue, behaves like other alpha-tubulin isotypes with respect to the cycle of tyrosination/detyrosination that occurs in most cultured cells.

scholarly journals The Roles of β-Tubulin Mutations and Isotype Expression in Acquired Drug Resistance

2007 ◽  
Vol 3 ◽  
pp. 117693510700300 ◽  
Author(s):  
J. Torin Huzil ◽  
Ke Chen ◽  
Lukasz Kurgan ◽  
Jack A. Tuszynski
Keyword(s):  
Drug Resistance ◽  
Rational Design ◽  
Resistant Cell ◽  
Microtubule Assembly ◽  
Acquired Drug Resistance ◽  
Tubulin Isotypes ◽  
Microtubule Disruption ◽  
Tubulin Isotype ◽  
Β Tubulin ◽  
Isotype Expression

The antitumor drug paclitaxel stabilizes microtubules and reduces their dynamicity, promoting mitotic arrest and eventually apoptosis. Upon assembly of the α/β-tubulin heterodimer, GTP becomes bound to both the α and β-tubulin monomers. During microtubule assembly, the GTP bound to β-tubulin is hydrolyzed to GDP, eventually reaching steady-state equilibrium between free tubulin dimers and those polymerized into microtubules. Tubulin-binding drugs such as paclitaxel interact with β-tubulin, resulting in the disruption of this equilibrium. In spite of several crystal structures of tubulin, there is little biochemical insight into the mechanism by which anti-tubulin drugs target microtubules and alter their normal behavior. The mechanism of drug action is further complicated, as the description of altered β-tubulin isotype expression and/or mutations in tubulin genes may lead to drug resistance as has been described in the literature. Because of the relationship between β-tubulin isotype expression and mutations within β-tubulin, both leading to resistance, we examined the properties of altered residues within the taxane, colchicine and Vinca binding sites. The amount of data now available, allows us to investigate common patterns that lead to microtubule disruption and may provide a guide to the rational design of novel compounds that can inhibit microtubule dynamics for specific tubulin isotypes or, indeed resistant cell lines. Because of the vast amount of data published to date, we will only provide a broad overview of the mutational results and how these correlate with differences between tubulin isotypes. We also note that clinical studies describe a number of predictive factors for the response to anti-tubulin drugs and attempt to develop an understanding of the features within tubulin that may help explain how they may affect both microtubule assembly and stability.

Comparative modelling of human β tubulin isotypes and implications for drug binding

2006 ◽  
Vol 17 (4) ◽  
pp. S90-S100 ◽  
Author(s):  
J Torin Huzil ◽  
Richard F Ludueña ◽  
Jack Tuszynski
Keyword(s):  
Drug Binding ◽  
Tubulin Isotypes ◽  
Comparative Modelling ◽  
Β Tubulin

scholarly journals TAPping into the treasures of tubulin using novel protein production methods

2018 ◽  
Vol 62 (6) ◽  
pp. 781-792
Author(s):  
Nuo Yu ◽  
Niels Galjart
Keyword(s):  
Mammalian Cells ◽  
Gene Families ◽  
Cell Types ◽  
Cellular Functions ◽  
Tubulin Isotypes ◽  
Associated Proteins ◽  
Cytoskeletal Elements ◽  
Different Cell Types ◽  
Β Tubulin

Microtubules are cytoskeletal elements with important cellular functions, whose dynamic behaviour and properties are in part regulated by microtubule-associated proteins (MAPs). The building block of microtubules is tubulin, a heterodimer of α- and β-tubulin subunits. Longitudinal interactions between tubulin dimers facilitate a head-to-tail arrangement of dimers into protofilaments, while lateral interactions allow the formation of a hollow microtubule tube that mostly contains 13 protofilaments. Highly homologous α- and β-tubulin isotypes exist, which are encoded by multi-gene families. In vitro studies on microtubules and MAPs have largely relied on brain-derived tubulin preparations. However, these consist of an unknown mix of tubulin isotypes with undefined post-translational modifications. This has blocked studies on the functions of tubulin isotypes and the effects of tubulin mutations found in human neurological disorders. Fortunately, various methodologies to produce recombinant mammalian tubulins have become available in the last years, allowing researchers to overcome this barrier. In addition, affinity-based purification of tagged tubulins and identification of tubulin-associated proteins (TAPs) by mass spectrometry has revealed the ‘tubulome’ of mammalian cells. Future experiments with recombinant tubulins should allow a detailed description of how tubulin isotype influences basic microtubule behaviour, and how MAPs and TAPs impinge on tubulin isotypes and microtubule-based processes in different cell types.

scholarly journals A Ubiquitous β-tubulin Disrupts Microtubule Assembly and Inhibits Cell Proliferation

2004 ◽  
Vol 15 (7) ◽  
pp. 3123-3131 ◽  
Author(s):  
Rajat Bhattacharya ◽  
Fernando Cabral
Keyword(s):  
Cell Proliferation ◽  
Mammalian Cells ◽  
Microtubule Assembly ◽  
Microtubule Organization ◽  
Class V ◽  
Tubulin Isotypes ◽  
Concomitant Reduction ◽  
Mitotic Spindle Assembly ◽  
Dose Dependent ◽  
Β Tubulin

Vertebrate tubulin is encoded by a multigene family that produces distinct gene products, or isotypes, of both the α- and β-tubulin subunits. The isotype sequences are conserved across species supporting the hypothesis that different isotypes subserve different functions. To date, however, most studies have demonstrated that tubulin isotypes are freely interchangeable and coassemble into all classes of microtubules. We now report that, in contrast to other isotypes, overexpression of a mouse class V β-tubulin cDNA in mammalian cells produces a strong, dose-dependent disruption of microtubule organization, increased microtubule fragmentation, and a concomitant reduction in cellular microtubule polymer levels. These changes also disrupt mitotic spindle assembly and block cell proliferation. Consistent with diminished microtubule assembly, there is an increased tolerance for the microtubule stabilizing drug, paclitaxel, which is able to reverse many of the effects of class V β-tubulin overexpression. Moreover, transfected cells selected in paclitaxel exhibit increased expression of class V β-tubulin, indicating that this isotype is responsible for the drug resistance. The results show that class V β-tubulin is functionally distinct from other tubulin isotypes and imparts unique properties on the microtubules into which it incorporates.

β-Tubulin Isotypes Purified from Bovine Brain Have Different Relative Stabilities†

Biochemistry ◽  
1998 ◽  
Vol 37 (13) ◽  
pp. 4687-4692 ◽  
Author(s):  
Patricia M. Schwarz ◽  
John R. Liggins ◽  
Richard F. Ludueña
Keyword(s):  
Bovine Brain ◽  
Relative Stabilities ◽  
Tubulin Isotypes ◽  
Β Tubulin

scholarly journals Identification of key interactions of benzimidazole resistance-associated amino acid mutations in Ascaris β-tubulins by molecular docking simulations

2021 ◽  
Author(s):  
Ben Paul Jones ◽  
Arnoud H. M. van Vliet ◽  
E. James La Course ◽  
Martha Betson
Keyword(s):  
Amino Acid ◽  
Obvious Effect ◽  
Middle Income ◽  
Docking Simulations ◽  
In Silico Docking ◽  
Tubulin Isotypes ◽  
Tubulin Isotype ◽  
Amino Acid Mutations ◽  
Dynamics Simulations ◽  
Β Tubulin

Ascaris species are soil-transmitted helminths that infect humans and livestock mainly in low and middle-income countries. Benzimidazole (BZ) class drugs have predominated for many years in the treatment of Ascaris infections, but persistent use of BZs has already led to widespread resistance in other nematodes, and treatment failure is emerging for Ascaris. Benzimidazoles act by binding to β-tubulin proteins and destabilising microtubules. Three mutations in the β-tubulin protein family are associated with BZ resistance. Seven shared β-tubulin isotypes were identified in Ascaris lumbricoides and A. suum genomes. Benzimidazoles were predicted to bind to all β-tubulin isotypes using in silico docking, demonstrating that the selectivity of BZs to interact with one or two β-tubulin isotypes is likely the result of isotype expression levels affecting the frequency of interaction. Ascaris β-tubulin isotype A clusters with helminth β-tubulins previously shown to interact with BZ. Molecular dynamics simulations using β-tubulin isotype A highlighted the key role of amino acid E198 in BZ-β-tubulin interactions. Simulations indicated that mutations at amino acids E198A and F200Y alter binding of BZ, whereas there was no obvious effect of the F167Y mutation. In conclusion, the key interactions vital for BZ binding with β-tubulins have been identified and show how mutations can lead to resistance in nematodes.

scholarly journals Identification of Key Interactions of Benzimidazole Resistance-Associated Amino Acid Mutations in Ascaris β-Tubulins By Molecular Docking Simulations

2021 ◽  
Author(s):  
Ben P. Jones ◽  
Arnoud H.M. Vliet ◽  
E. James LaCourse ◽  
Martha Betson
Keyword(s):  
Amino Acid ◽  
Obvious Effect ◽  
Middle Income ◽  
Docking Simulations ◽  
Tubulin Isotypes ◽  
Tubulin Isotype ◽  
Amino Acid Mutations ◽  
Dynamics Simulations ◽  
Tubulin Protein ◽  
Β Tubulin

Abstract Ascaris species are soil-transmitted helminths that infect humans and livestock mainly in low and middle-income countries. Benzimidazole (BZ) class drugs have predominated for many years in the treatment of Ascaris infections, but persistent use of BZs has already led to widespread resistance in other nematodes, and treatment failure is emerging for Ascaris. Benzimidazoles act by binding to β-tubulin proteins and destabilising microtubules. Three mutations in the β-tubulin protein family are associated with BZ resistance. Seven shared β-tubulin isotypes were identified in Ascaris lumbricoides and A. suum genomes. Benzimidazoles were predicted to bind to all β-tubulin isotypes using in silico docking, demonstrating that the selectivity of BZs to interact with one or two β-tubulin isotypes is likely the result of isotype expression levels affecting the frequency of interaction. Ascaris β-tubulin isotype A clusters with helminth β-tubulins previously shown to interact with BZ. Molecular dynamics simulations using β-tubulin isotype A highlighted the key role of amino acid E198 in BZ-β-tubulin interactions. Simulations indicated that mutations at amino acids E198A and F200Y alter binding of BZ, whereas there was no obvious effect of the F167Y mutation. In conclusion, the key interactions vital for BZ binding with β-tubulins have been identified and show how mutations can lead to resistance in nematodes.

scholarly journals Primary myeloid cell proteomics and transcriptomics: importance of ß tubulin isotypes for osteoclast function

2019 ◽  
Author(s):  
David Guérit ◽  
Pauline Marie ◽  
Anne Morel ◽  
Justine Maurin ◽  
Christel Verollet ◽  
...  
Keyword(s):  
Dendritic Cells ◽  
Myeloid Cells ◽  
Zone Structure ◽  
Tubulin Isotypes ◽  
Immature Dendritic Cells ◽  
Tubulin Isotype ◽  
Gene And Protein Expression ◽  
Primary Mouse ◽  
Sealing Zone ◽  
Β Tubulin

AbstractAmong hematopoietic cells. osteoclasts (Oc) and immature dendritic cells (Dc) are closely related myeloid cells with distinct functions; Oc participate skeleton maintenance while Dc sample the environment for foreign antigens. Such specificities rely on profound modifications of gene and protein expression during Oc and Dc differentiation. We provide global proteomic and transcriptomic analyses of primary mouse Oc and Dc. based on original SILAC and RNAseq data. We established specific signatures for Oc and Dc including genes and proteins of unknown functions. In particular. we showed that Oc and Dc have the same α and β tubulin isotypes repertoire but that Oc express much more β tubulin isotype Tubb6. In both mouse and human Oc. we demonstrate that elevated expression of Tubb6 in Oc is necessary for correct podosomes organization and thus for the structure of the sealing zone. which sustains the bone resorption apparatus. Hence. lowering Tubb6 expression hindered Oc resorption activity. Overall. we highlight here potential new regulators of Oc and Dc biology and illustrate the functional importance of the tubulin isotype repertoire in the biology of differentiated cells.Summary statementThis study provides original proteomic and transcriptomic data of primary myeloid cells. The analysis led to signatures for osteoclasts and for immature dendritic cells including potential new regulators of their specific biology. RNA interference showed in particular that ß tubulin isotype Tubb6 participates in osteoclast podosome patterning. sealing zone structure and in the resorption activity.

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