1
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Chen D, Wu C, Hao C, Huang P, Liu H, Bian Z, Xu JR. Sexual specific functions of Tub1 beta-tubulins require stage-specific RNA processing and expression in Fusarium graminearum. Environ Microbiol 2018; 20:4009-4021. [PMID: 30307105 DOI: 10.1111/1462-2920.14441] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 10/04/2018] [Accepted: 10/05/2018] [Indexed: 11/27/2022]
Abstract
The wheat head blight fungus Fusarium graminearum has two highly similar beta-tubulin genes with overlapping functions during vegetative growth but only TUB1 is important for sexual reproduction. To better understand their functional divergence during ascosporogenesis, in this study we characterized the sequence elements important for stage-specific functions of TUB1. Deletion of TUB1 blocked the late but not initial stages of perithecium formation. Perithecia formed by tub1 mutant had limited ascogenous hyphae and failed to develop asci. Silencing of TUB1 by MSUD also resulted in defects in ascospore formation. Interestingly, the 3'-UTR of TUB1 was dispensable for growth but essential for its function during sexual reproduction. RIP mutations that specifically affected Tub1 functions during sexual reproduction also were identified in two ascospore progeny. Furthermore, site-directed mutagenesis showed that whereas the non-editable mutations at three A-to-I RNA editing sites had no effects, the N347D (not T362D or I368V) edited mutation affected ascospore development. In addition, the F167Y, but not E198K or F200Y, mutation in TUB1 conferred tolerance to carbendazim and caused a minor defect in sexual reproduction. Taken together, our data indicate TUB1 plays an essential role in ascosporogenesis and sexual-specific functions of TUB1 require stage-specific RNA processing and Tub1 expression.
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Affiliation(s)
- Daipeng Chen
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, 712100, China.,Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, 47907, USA
| | - Chunlan Wu
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Chaofeng Hao
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Panpan Huang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Huiquan Liu
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Zhuyun Bian
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, 47907, USA
| | - Jin-Rong Xu
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, 47907, USA
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2
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Zúñiga MA, Alderete JB, Jaña GA, Jiménez VA. Structural insight into the role of Gln293Met mutation on the Peloruside A/Laulimalide association with αβ-tubulin from molecular dynamics simulations, binding free energy calculations and weak interactions analysis. J Comput Aided Mol Des 2017; 31:643-652. [DOI: 10.1007/s10822-017-0029-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 05/28/2017] [Indexed: 01/27/2023]
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3
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Zampanolide, a Microtubule-Stabilizing Agent, Is Active in Resistant Cancer Cells and Inhibits Cell Migration. Int J Mol Sci 2017; 18:ijms18050971. [PMID: 28467385 PMCID: PMC5454884 DOI: 10.3390/ijms18050971] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2017] [Revised: 04/28/2017] [Accepted: 04/28/2017] [Indexed: 12/19/2022] Open
Abstract
Zampanolide, first discovered in a sponge extract in 1996 and later identified as a microtubule-stabilizing agent in 2009, is a covalent binding secondary metabolite with potent, low nanomolar activity in mammalian cells. Zampanolide was not susceptible to single amino acid mutations at the taxoid site of β-tubulin in human ovarian cancer 1A9 cells, despite evidence that it selectively binds to the taxoid site. As expected, it did not synergize with other taxoid site microtubule-stabilizing agents (paclitaxel, ixabepilone, discodermolide), but surprisingly also did not synergize in 1A9 cells with laulimalide/peloruside binding site agents either. Efforts to generate a zampanolide-resistant cell line were unsuccessful. Using a standard wound scratch assay in cell culture, it was an effective inhibitor of migration of human umbilical vein endothelial cells (HUVEC) and fibroblast cells (D551). These properties of covalent binding, the ability to inhibit cell growth in paclitaxel and epothilone resistant cells, and the ability to inhibit cell migration suggest that it would be of interest to investigate zampanolide in preclinical animal models to determine if it is effective in vivo at preventing tumor growth and metastasis.
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4
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Woods LM, Arico JW, Frein JD, Sackett DL, Taylor RE. Synthesis and Biological Evaluation of 7-Deoxy-Epothilone Analogues. Int J Mol Sci 2017; 18:E648. [PMID: 28304361 PMCID: PMC5372660 DOI: 10.3390/ijms18030648] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 02/06/2017] [Accepted: 02/22/2017] [Indexed: 01/27/2023] Open
Abstract
The synthesis of two deoxygenated analogues of potent epothilones is reported in an effort to analyze the relative importance of molecular conformation and ligand-target interactions to biological activity. 7-deoxy-epothilone D and 7-deoxy-(S)-14-methoxy-epothilone D were prepared through total synthesis and shown to maintain the conformational preferences of their biologically active parent congeners through computer modeling and nuclear magnetic resonance (NMR) studies. The significant decrease in observed potency for each compound suggests that a hydrogen bond between the C7-hydroxyl group and the tubulin binding site plays a critical role in the energetics of binding in the epothilone class of polyketides.
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Affiliation(s)
- Laura M Woods
- Department of Chemistry and Biochemistry, the Harper Cancer Research Institute, and the Warren Family Research Center for Drug Discovery & Development, University of Notre Dame, Notre Dame, IN 46556, USA.
| | - Joseph W Arico
- Department of Chemistry and Biochemistry, the Harper Cancer Research Institute, and the Warren Family Research Center for Drug Discovery & Development, University of Notre Dame, Notre Dame, IN 46556, USA.
| | - Jeffrey D Frein
- Department of Chemistry and Biochemistry, the Harper Cancer Research Institute, and the Warren Family Research Center for Drug Discovery & Development, University of Notre Dame, Notre Dame, IN 46556, USA.
| | - Dan L Sackett
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Richard E Taylor
- Department of Chemistry and Biochemistry, the Harper Cancer Research Institute, and the Warren Family Research Center for Drug Discovery & Development, University of Notre Dame, Notre Dame, IN 46556, USA.
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5
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Kanakkanthara A, Northcote PT, Miller JH. Peloruside A: a lead non-taxoid-site microtubule-stabilizing agent with potential activity against cancer, neurodegeneration, and autoimmune disease. Nat Prod Rep 2016; 33:549-61. [PMID: 26867978 DOI: 10.1039/c5np00146c] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Covering: 2000 up to 2016Peloruside A, a macrocyclic secondary metabolite from a New Zealand marine sponge, Mycale hentscheli, has shown potent antiproliferative activity in cultured cancer cells as well as inhibitory effects on tumor growth in mouse models. The compound also has promising effects against cell models of neurodegenerative and autoimmune diseases. In mechanistic studies, peloruside A shares with paclitaxel (Taxol®) the ability to stabilize microtubules by binding to β-tubulin. Peloruside A, however, occupies a unique external site on β-tubulin that does not overlap the classical taxoid site that is located on the inside of the microtubule. As such, peloruside A has been of central importance in defining a new microtubule-stabilizer binding site localized on the exterior surface of the microtubule that has led to increased interest in the design of an upscaled total synthesis of the natural product and its analogues. Here, we review advances in the biochemical and biological validation of peloruside A as an attractive therapeutic candidate for the treatment of cancer, neurodegeneration, and autoimmune disease.
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Affiliation(s)
- Arun Kanakkanthara
- Department of Pediatric and Adolescent Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN, USA 55905.
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6
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Majumdar S, Maiti S, Ghosh Dastidar S. Dynamic and Static Water Molecules Complement the TN16 Conformational Heterogeneity inside the Tubulin Cavity. Biochemistry 2015; 55:335-47. [DOI: 10.1021/acs.biochem.5b00853] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Sarmistha Majumdar
- Bioinformatics
Centre, Bose Institute, P-1/12 C.I.T. Scheme VII M, Kolkata, India 700054
| | - Satyabrata Maiti
- Bioinformatics
Centre, Bose Institute, P-1/12 C.I.T. Scheme VII M, Kolkata, India 700054
| | - Shubhra Ghosh Dastidar
- Bioinformatics
Centre, Bose Institute, P-1/12 C.I.T. Scheme VII M, Kolkata, India 700054
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7
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Larsen EM, Wilson MR, Taylor RE. Conformation-activity relationships of polyketide natural products. Nat Prod Rep 2015; 32:1183-206. [PMID: 25974024 PMCID: PMC4443481 DOI: 10.1039/c5np00014a] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Polyketides represent an important class of secondary metabolites that interact with biological targets connected to a variety of disease-associated pathways. Remarkably, nature's assembly lines, polyketide synthases, manufacture these privileged structures through a combinatorial mixture of just a few structural units. This review highlights the role of these structural elements in shaping a polyketide's conformational preferences, the use of computer-based molecular modeling and solution NMR studies in the identification of low-energy conformers, and the importance of conformational analogues in probing the bound conformation. In particular, this review covers several examples wherein conformational analysis complements classic structure-activity relationships in the design of biologically active natural product analogues.
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Affiliation(s)
- Erik M Larsen
- University of Notre Dame, Department of Chemistry & Biochemistry, 250 Nieuwland Science Hall, Notre Dame, Indiana, USA.
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8
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βI-tubulin mutations in the laulimalide/peloruside binding site mediate drug sensitivity by altering drug-tubulin interactions and microtubule stability. Cancer Lett 2015; 365:251-60. [PMID: 26052091 DOI: 10.1016/j.canlet.2015.06.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Revised: 05/21/2015] [Accepted: 06/01/2015] [Indexed: 01/04/2023]
Abstract
Peloruside A (PLA) and laulimalide (LAU) are potent microtubule-stabilizing natural products that are effective against a broad spectrum of cancer cells. The interactions of PLA and LAU with tubulin have attracted a great deal of attention, mainly because they bind to β-tubulin at a site that is different from the classical taxoid site. Multiple βI-tubulin amino acid residues have been predicted by computer modelling studies and more recently by protein crystallography to participate in the binding of PLA and LAU to tubulin. The relevance of these residues in determining cellular sensitivity to the compounds, however, remains largely uncertain. To determine the role of four binding site residues, Q291, D295, V333, and N337 on PLA and LAU activity, we introduced single mutations to these sites by site-directed mutagenesis and transfected each mutant tubulin separately into HEK and/or HeLa cells. We found that a Q291M βI-tubulin mutation increased sensitivity of the cells to PLA, but not to LAU, paclitaxel (PTX), or vinblastine (VBL). In contrast, V333W and N337L mutations led to less stable microtubules, with the V333W causing resistance to PLA and PTX, but not LAU, and the N337L causing resistance to PLA, LAU, and PTX. Moreover, cells expressing either W333 or L337 were hypersensitive to the microtubule-destabilizing agent, VBL. The D295I mutation conferred resistance to both PLA and LAU without affecting microtubule stability or sensitivity to PTX or ixabepilone (IXB). This study identifies the first mammalian βI-tubulin mutation that specifically increases sensitivity to PLA, and reports mutations at PLA and LAU binding site residues that can either reduce microtubule stability or impair drug-tubulin binding, conferring resistance to these microtubule-stabilizing agents. This information provides insights on β-tubulin residues important for maintaining microtubule structural integrity and for sensitivity to microtubule-targeting agents, and suggests novel directions for rational structure-based design of new and more potent agents for cancer treatment that target the LAU/PLA site.
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9
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Rohena CC, Mooberry SL. Recent progress with microtubule stabilizers: new compounds, binding modes and cellular activities. Nat Prod Rep 2014; 31:335-55. [PMID: 24481420 PMCID: PMC4167679 DOI: 10.1039/c3np70092e] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Nature has yielded numerous classes of chemically distinct microtubule stabilizers. Several of these, including paclitaxel (Taxol) and docetaxel (Taxotere), are important drugs used in the treatment of cancer. New microtubule stabilizers and novel formulations of these agents continue to provide advances in cancer therapy. In this review we cover recent progress in the chemistry and biology of these diverse microtubule stabilizers focusing on the wide range of organisms that produce these compounds, their mechanisms of inhibiting microtubule-dependent processes, mechanisms of drug resistance, and their interactions with tubulin including their distinct binding sites and modes. A new potential role for microtubule stabilizers in neurodegenerative diseases is reviewed.
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Affiliation(s)
- Cristina C. Rohena
- University of Texas Health Science Center at San Antonio,
7703 Floyd Curl Dr, San Antonio, TX, USA. Fax: 1(210)567-4300; Tel: 1(210) 567-6674;
| | - Susan L. Mooberry
- University of Texas Health Science Center at San Antonio,
7703 Floyd Curl Dr, San Antonio, TX, USA. Fax: 1(210)567-4300; Tel: 1(210) 567-6674;
- Cancer Therapy Research Center, 7979 Wurzbach Rd, San
Antonio, TX USA. Fax: 1(210)567-4300; Tel: 1(210) 567-4788;
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10
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Yin S, Zeng C, Hari M, Cabral F. Paclitaxel resistance by random mutagenesis of α-tubulin. Cytoskeleton (Hoboken) 2013; 70:849-62. [DOI: 10.1002/cm.21154] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 10/11/2013] [Accepted: 10/17/2013] [Indexed: 12/12/2022]
Affiliation(s)
- Shanghua Yin
- Department of Integrative Biology and Pharmacology; University of Texas Medical School; Houston Texas
| | - Changqing Zeng
- Department of Integrative Biology and Pharmacology; University of Texas Medical School; Houston Texas
| | - Malathi Hari
- Department of Integrative Biology and Pharmacology; University of Texas Medical School; Houston Texas
| | - Fernando Cabral
- Department of Integrative Biology and Pharmacology; University of Texas Medical School; Houston Texas
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11
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Hanna R, Maass DR, Atkinson PH, Northcote PT, Teesdale-Spittle PH, Bellows DS, Miller JH. Characterizing the laulimalide-peloruside binding site using site-directed mutagenesis of TUB2 in S. cerevisiae. MOLECULAR BIOSYSTEMS 2013; 10:110-6. [PMID: 24161989 DOI: 10.1039/c3mb70380k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Baker's yeast, Saccharomyces cerevisiae, has significant sequence conservation with a core subset of mammalian proteins and can serve as a model for disease processes. The aim of this study was to determine whether yeast could be used as a model system to identify new agents that interact with the laulimalide-peloruside binding site on β-tubulin. Agents that bind to this site cause stabilization of microtubules and interfere with cell division. Based on the location of the proposed laulimalide-peloruside binding site and of previously identified mutations shown to cause resistance in mammalian cells, we made the corresponding mutations in yeast and tested whether they conferred resistance to laulimalide and peloruside. Mutations A296T and R306H, which cause 6-fold and 40-fold increased resistance in human 1A9 ovarian carcinoma cells, respectively, also led to resistance in yeast to these compounds. Similarly, other mutations led to resistance or, in one case, increased sensitivity. Thus, we conclude that yeast is an appropriate model to screen for small molecule drugs that may be efficacious in cancer therapy in humans through the newly characterised laulimalide-peloruside binding site.
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Affiliation(s)
- Reem Hanna
- Centre for Biodiscovery, School of Biological Sciences, Victoria University of Wellington, Kelburn Parade, Kelburn, Wellington, 6012, New Zealand.
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12
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Wullschleger CW, Gertsch J, Altmann KH. Synthesis and Biological Activity of 7,8,9-Trideoxy- and 7RDesTHP-Peloruside A. Chemistry 2013; 19:13105-11. [DOI: 10.1002/chem.201301796] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Indexed: 11/09/2022]
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13
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Field J, Díaz J, Miller J. The Binding Sites of Microtubule-Stabilizing Agents. ACTA ACUST UNITED AC 2013; 20:301-15. [DOI: 10.1016/j.chembiol.2013.01.014] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 01/14/2013] [Accepted: 01/17/2013] [Indexed: 11/25/2022]
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14
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Chakraborti S, Chakravarty D, Gupta S, Chatterji BP, Dhar G, Poddar A, Panda D, Chakrabarti P, Ghosh Dastidar S, Bhattacharyya B. Discrimination of ligands with different flexibilities resulting from the plasticity of the binding site in tubulin. Biochemistry 2012; 51:7138-48. [PMID: 22891709 DOI: 10.1021/bi300474q] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Tubulin, an α,β heterodimer, has four distinct ligand binding sites (for paclitaxel, peloruside/laulimalide, vinca, and colchicine). The site where colchicine binds is a promising drug target for arresting cell division and has been observed to accommodate compounds that are structurally diverse but possess comparable affinity. This investigation, using two such structurally different ligands as probes (one being colchicine itself and another, TN16), aims to provide insight into the origin of this diverse acceptability to provide a better perspective for the design of novel therapeutic molecules. Thermodynamic measurements reveal interesting interplay between entropy and enthalpy. Although both these parameters are favourable for TN16 binding (ΔH < 0, ΔS > 0), but the magnitude of entropy has the determining role for colchicine binding as its enthalpic component is destabilizing (ΔH > 0, ΔS > 0). Molecular dynamics simulation provides atomistic insight into the mechanism, pointing to the inherent flexibility of the binding pocket that can drastically change its shape depending on the ligand that it accepts. Simulation shows that in the complexed states both the ligands have freedom to move within the binding pocket; colchicine can switch its interactions like a "flying trapeze", whereas TN16 rocks like a "swing cradle", both benefiting entropically, although in two different ways. Additionally, the experimental results with respect to the role of solvation entropy correlate well with the computed difference in the hydration: water molecules associated with the ligands are released upon complexation. The complementary role of van der Waals packing versus flexibility controls the entropy-enthalpy modulations. This analysis provides lessons for the design of new ligands that should balance between the "better fit" and "flexibility"', instead of focusing only on the receptor-ligand interactions.
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15
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Bennett MJ, Chan GK, Rattner JB, Schriemer DC. Low-dose laulimalide represents a novel molecular probe for investigating microtubule organization. Cell Cycle 2012; 11:3045-54. [PMID: 22871740 DOI: 10.4161/cc.21411] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Laulimalide is a natural product that has strong taxoid-like properties but binds to a distinct site on β-tubulin in the microtubule (MT) lattice. At elevated concentrations, it generates MTs that are resistant to depolymerization, and it induces a conformational state indistinguishable from taxoid-treated MTs. In this study, we describe the effect of low-dose laulimalide on various stages of the cell cycle and compare these effects to docetaxel as a representative of taxoid stabilizers. No evidence of MT bundling in interphase was observed with laulimalide, in spite of the fact that MTs are stabilized at low dose. Cells treated with laulimalide enter mitosis but arrest at prometaphase by generating multiple asters that coalesce into supernumerary poles and interfere with the integrity of the metaphase plate. Cells with a preformed bipolar spindle exist under heightened tension under laulimalide treatment, and chromosomes rapidly shear from the plate, even though the bipolar spindle is well-preserved. Docetaxel generates a similar phenotype for HeLa cells entering mitosis, but when treated at metaphase, cells undergo chromosomal fragmentation and demonstrate reduced centromere dynamics, as expected for a taxoid. Our results suggest that laulimalide represents a new class of molecular probe for investigating MT-mediated events, such as kinetochore-MT interactions, which may reflect the location of the ligand binding site within the interprotofilament groove.
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Affiliation(s)
- Melissa J Bennett
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta, Canada
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16
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Peloruside, Laulimalide, and Noscapine Interactions with Beta-Tubulin. Pharm Res 2012; 29:2985-93. [DOI: 10.1007/s11095-012-0809-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Accepted: 06/11/2012] [Indexed: 02/04/2023]
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17
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Wilson MR, Taylor RE. Toward an enantioselective synthesis of (-)-zampanolide: preparation of the C9-C20 region. Org Lett 2012; 14:3408-11. [PMID: 22720980 DOI: 10.1021/ol301383a] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Progress toward the synthesis of the microtubule-stabilizing agent, (-)-zampanolide, is reported. Construction of the 2,6-cis-tetrahydropyran ring was accomplished utilizing ether transfer methodology in conjunction with an intramolecular radical cyclization reaction. Efficient installation of the C16-C20 side chain relied on a one-pot cross-metathesis/olefination sequence, Sharpless epoxidation, and selective reduction of a vinyl epoxide.
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Affiliation(s)
- Matthew R Wilson
- Department of Chemistry and Biochemistry and the Walther Cancer Research Center, University of Notre Dame, 251 Nieuwland Science Hall, Notre Dame, Indiana 46556-5670, USA
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18
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Yin S, Zeng C, Hari M, Cabral F. Random mutagenesis of β-tubulin defines a set of dispersed mutations that confer paclitaxel resistance. Pharm Res 2012; 29:2994-3006. [PMID: 22669706 DOI: 10.1007/s11095-012-0794-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Accepted: 05/21/2012] [Indexed: 01/14/2023]
Abstract
PURPOSE Previous research showed that mutations in β1-tubulin are frequently involved in paclitaxel resistance but the question of whether the mutations are restricted by cell-type specific differences remains obscure. METHODS To circumvent cellular constraints, we randomly mutagenized β-tubulin cDNA, transfected it into CHO cells, and selected for paclitaxel resistance. RESULTS A total of 26 β1-tubulin mutations scattered throughout the sequence were identified and a randomly chosen subset were confirmed to confer paclitaxel resistance using site-directed mutagenesis of β-tubulin cDNA and transfection into wild-type cells. Immunofluorescence microscopy and biochemical fractionation studies indicated that cells expressing mutant tubulin had decreased microtubule polymer and frequently suffered mitotic defects that led to the formation of large multinucleated cells, suggesting a resistance mechanism that involves destabilization of the microtubule network. Consistent with this conclusion, the mutations were predominantly located in regions that are likely to be involved in lateral or longitudinal subunit interactions. Notably, fourteen of the new mutations overlapped previously reported mutations in drug resistant cells or in patients with developmental brain abnormalities. CONCLUSIONS A random mutagenesis approach allowed isolation of a wider array of drug resistance mutations and demonstrated that similar mutations can cause paclitaxel resistance and human neuronal abnormalities.
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Affiliation(s)
- Shanghua Yin
- Department of Integrative Biology and Pharmacology, University of Texas Medical School, 6431 Fannin St., Houston, Texas 77030, USA
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19
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Kanakkanthara A, Northcote PT, Miller JH. βII-Tubulin and βIII-Tubulin Mediate Sensitivity to Peloruside A and Laulimalide, but not Paclitaxel or Vinblastine, in Human Ovarian Carcinoma Cells. Mol Cancer Ther 2012; 11:393-404. [DOI: 10.1158/1535-7163.mct-11-0614] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Increased abundance of βII- and βIII-tubulin isotypes in cancer cells confers resistance to vinca and taxoid site drugs; however, the role of these isotypes in the acquired resistance of cancer cells to non-vinca or non-taxoid site binding agents has not been described. Peloruside A (PLA) and laulimalide are the only known non-taxoid site microtubule-stabilizing agents. A human ovarian cancer cell line, 1A9-L4 (L4), previously selected in high concentrations of laulimalide, has both a single point mutation in βI-tubulin and overexpression of βII- and βIII-tubulin. The cells are highly resistant to PLA as well as laulimalide but show no cross-resistance to taxoid site drugs or drugs that bind to the vinca site on β-tubulin. To understand the functional significance of the βII- and βIII-tubulin changes in this resistant cell line, isotype-specific short interfering RNA was used to knock down the expression of the βII and βIII isotypes, and the cellular effects of PLA and laulimalide were examined before and after silencing. It was found that inhibition of βII- and βIII-tubulin partially sensitized L4 cells to PLA and laulimalide, as seen by increased potency of PLA and laulimalide for inducing growth inhibition, cellular tubulin polymerization, microtubule aberrations, and G2-M arrest in the resistant cells. The sensitivity to paclitaxel, vinblastine, ixabepilone, and cisplatin was unaffected by the inhibition of isotype expression. It was concluded that the increased βII- and βIII-tubulin contributed significantly to the resistance phenotype, along with the tubulin structural mutation, and that the altered isotype effect was binding site specific. Mol Cancer Ther; 11(2); 393–404. ©2011 AACR.
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Affiliation(s)
- Arun Kanakkanthara
- Authors' Affiliations: 1Centre for Biodiscovery and Schools of 2Biological Sciences and 3Chemical and Physical Sciences, Victoria University of Wellington, Wellington, New Zealand
- Authors' Affiliations: 1Centre for Biodiscovery and Schools of 2Biological Sciences and 3Chemical and Physical Sciences, Victoria University of Wellington, Wellington, New Zealand
| | - Peter T. Northcote
- Authors' Affiliations: 1Centre for Biodiscovery and Schools of 2Biological Sciences and 3Chemical and Physical Sciences, Victoria University of Wellington, Wellington, New Zealand
- Authors' Affiliations: 1Centre for Biodiscovery and Schools of 2Biological Sciences and 3Chemical and Physical Sciences, Victoria University of Wellington, Wellington, New Zealand
| | - John H. Miller
- Authors' Affiliations: 1Centre for Biodiscovery and Schools of 2Biological Sciences and 3Chemical and Physical Sciences, Victoria University of Wellington, Wellington, New Zealand
- Authors' Affiliations: 1Centre for Biodiscovery and Schools of 2Biological Sciences and 3Chemical and Physical Sciences, Victoria University of Wellington, Wellington, New Zealand
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Abstract
An efficient synthetic strategy for rapid access to analogues of peloruside A has been demonstrated. The synthetic route was highlighted by a simple esterification-based fragment coupling and a late stage ring-closing metathesis reaction. This convergent route has provided access to rationally designed analogues inspired by the solution conformational preferences of peloruside A.
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Affiliation(s)
- Zhiming Zhao
- Department of Chemistry and Biochemistry and the Mike and Josie Harper Cancer Research Institute, University of Notre Dame, 251 Nieuwland Science Hall, Notre Dame, Indiana 46556-5670, USA
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