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Różańska E, Czarnocka W, Baranowski Ł, Mielecki J, de Almeida Engler J, Sobczak M. Expression of both Arabidopsis γ-tubulin genes is essential for development of a functional syncytium induced by Heterodera schachtii. PLANT CELL REPORTS 2018; 37:1279-1292. [PMID: 29947953 PMCID: PMC6096582 DOI: 10.1007/s00299-018-2312-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 06/04/2018] [Indexed: 05/23/2023]
Abstract
After initial up-regulation, expression of TUBG1 and TUBG2 is significantly down-regulated in mature syncytia, but lack of expression of either of γ-tubulin genes reduces numbers of nematode infections and developing females. Infective second stage juveniles of sedentary plant parasitic nematode Heterodera schachtii invade the root vascular tissue and induce a feeding site, named syncytium, formed as a result of cell hypertrophy and partial cell wall dissolution leading to a multinucleate state. Syncytium formation and maintenance involves a molecular interplay between the plant host and the developing juveniles leading to rearrangements and fragmentation of the plant cytoskeleton. In this study, we investigated the role of two Arabidopsis γ-tubulin genes (TUBG1 and TUBG2), involved in MTs nucleation during syncytium development. Expression analysis revealed that both γ-tubulin's transcript levels changed during syncytium development and after initial up-regulation (1-3 dpi) they were significantly down-regulated in 7, 10 and 15 dpi syncytia. Moreover, TUBG1 and TUBG2 showed distinct immunolocalization patterns in uninfected roots and syncytia. Although no severe changes in syncytium anatomy and ultrastructure in tubg1-1 and tubg2-1 mutants were observed compared to syncytia induced in wild-type plants, nematode infection assays revealed reduced numbers of infecting juveniles and developed female nematodes in mutant lines. Our results indicate that the expression of both TUBG1 and TUBG2 genes, although generally down-regulated in mature syncytia, is essential for successful root infection, development of functional syncytium and nematode maturation.
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Affiliation(s)
- Elżbieta Różańska
- Department of Botany, Faculty of Agriculture and Biology, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159, 02-776, Warsaw, Poland
| | - Weronika Czarnocka
- Department of Botany, Faculty of Agriculture and Biology, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159, 02-776, Warsaw, Poland
| | - Łukasz Baranowski
- Department of Botany, Faculty of Agriculture and Biology, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159, 02-776, Warsaw, Poland
| | - Jakub Mielecki
- Department of Plant Genetics, Breeding and Biotechnology, Faculty of Horticulture, Biotechnology and Landscape Architecture, Warsaw University of Life Sciences-SGGW, Warsaw, Poland
| | | | - Mirosław Sobczak
- Department of Botany, Faculty of Agriculture and Biology, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159, 02-776, Warsaw, Poland.
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Mussali-Galante P, Rodríguez-Lara V, Hernández-Tellez B, Avila-Costa MR, Colín-Barenque L, Bizarro-Nevarez P, Martínez-Levy G, Rojas-Lemus M, Piñón-Zarate G, Saldivar-Osorio L, Diaz-Beck P, Herrera-Enríquez MA, Tovar-Sánchez E, Fortoul TI. Inhaled vanadium pentoxide decrease gamma-tubulin of mouse testes at different exposure times. Toxicol Ind Health 2016; 21:215-22. [PMID: 16342472 DOI: 10.1191/0748233705th232oa] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Vanadium is an important environmental and industrial pollutant whose concentrations have increased in the last decades. Due to its status as reproductive toxicant and a microtubule damaging agent, the present study investigated by immunohistochemistry the effect of the inhalation of vanadium pentoxide on gamma-tubulin within somatic and testicular germ cells. Male mice inhaled vanadium pentoxide (V2O5) (0.02 M) 1 h/twice a week for 12 weeks. Our results demonstrated that vanadium accumulates in the testes starting with the initial inhalation (24 h), and this pattern remained until the last week of treatment. In general, vanadium was capable of significantly decreasing the percentage of gamma-tubulin in all analyzed testicular cells (Sertoli, Leydig and germ cells) starting with the first week of treatment. For all cell types studied, regression analysis revealed a negative and significant relationship between the percentage of immunopositive cells to gamma-tubulin and exposure time, showing a time dependent response in all cases. Our findings suggest that alterations on this protein might imply changes in microtubule-involved function such as cell division, which in the testes might lead to damage in the spermatogenesis, leading probably to infertility.
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Affiliation(s)
- Patricia Mussali-Galante
- Departamento de Biologia Celular y Tisular, Facultad de Medicina, Universidad Nacional Autónoma de Mexico, Mexico City
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3
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Lott JR, McAllister JW, Wasbrough M, Sammler RL, Bates FS, Lodge TP. Fibrillar Structure in Aqueous Methylcellulose Solutions and Gels. Macromolecules 2013. [DOI: 10.1021/ma4021642] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Joseph R. Lott
- Department
of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - John W. McAllister
- Department
of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Matthew Wasbrough
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899-1070, United States
- Department
of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716, United States
| | - Robert L. Sammler
- Materials
Science and Engineering, The Dow Chemical Company, Midland, Michigan 48674, United States
| | - Frank S. Bates
- Department of Chemical Engineering & Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Timothy P. Lodge
- Department
of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
- Department of Chemical Engineering & Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
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Rogers MA. Co-operative self-assembly of cholesterol and γ-oryzanol composite crystals. CrystEngComm 2011. [DOI: 10.1039/c1ce05818e] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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6
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Cho EH, Whipple RA, Matrone MA, Balzer EM, Martin SS. Delocalization of gamma-tubulin due to increased solubility in human breast cancer cell lines. Cancer Biol Ther 2010; 9:66-76. [PMID: 20009567 DOI: 10.4161/cbt.9.1.10451] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The centrosome is the major organelle responsible for the nucleation and organization of microtubules into arrays. Recent studies demonstrate that microtubules can nucleate outside the centrosome. The molecular mechanisms controlling acentrosomal microtubule nucleation are currently poorly defined, and the function of this type of microtubule regulation in tumor cell biology is particularly unclear. Since microtubule nucleation is initiated by the gamma-tubulin protein, we examined the regulation of gamma-tubulin in a panel of human breast tumor cell lines, ranging from non-tumorigenic to highly aggressive. We have identified a more dispersive subcellular localization of gamma-tubulin in aggressive breast cancer cell lines, while gamma-tubulin localization remains largely centrosomal in non-aggressive cell lines. Delocalization of gamma-tubulin occurs independently from changes in protein expression and is therefore regulated at the post-translational level. Subcellular fractionation revealed that tumor cell lines show an aberrantly increased release of gamma-tubulin into a soluble cytoplasmic fraction, with the most dramatic changes observed in tumor cell lines of greater aggressiveness. Extraction of soluble gamma-tubulin revealed acentrosomal incorporation of gamma-tubulin in cytoplasmic microtubules and along cell junctions. Moreover, acentrosomal delocalization of gamma-tubulin yielded resistance to colchicine-mediated microtubule collapse. These findings support a model where the solubility of gamma-tubulin can be altered through post-translational modification and provides a new mechanism for microtubule dysregulation in breast cancer. Gamma-tubulin that is delocalized from the centrosome can still clearly be incorporated into filaments, and defines a novel mechanism for tumor cells to develop resistance to microtubule-targeted chemotherapies.
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Affiliation(s)
- Edward H Cho
- University of Maryland School of Medicine and Graduate Program in Life Sciences, Marlene and Stewart Greenebaum NCI Cancer Center, Department of Physiology, Baltimore, MD, USA
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DiMaio MA, Mikhailov A, Rieder CL, Von Hoff DD, Palazzo RE. The small organic compound HMN-176 delays satisfaction of the spindle assembly checkpoint by inhibiting centrosome-dependent microtubule nucleation. Mol Cancer Ther 2009; 8:592-601. [PMID: 19258425 DOI: 10.1158/1535-7163.mct-08-0876] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
HMN-176 is a potential new cancer therapeutic known to retard the proliferation of tumor cell lines. Here, we show that this compound inhibits meiotic spindle assembly in surf clam oocytes and delays satisfaction of the spindle assembly checkpoint in human somatic cells by inducing the formation of short and/or multipolar spindles. HMN-176 does not affect centrosome assembly, nuclear envelope breakdown, or other aspects of meiotic or mitotic progression, nor does it affect the kinetics of Spisula or mammalian microtubule (MT) assembly in vitro. Notably, HMN-176 inhibits the formation of centrosome-nucleated MTs (i.e., asters) in Spisula oocytes and oocyte extracts, as well as from isolated Spisula or mammalian centrosomes in vitro. Together, these results reveal that HMN-176 is a first-in-class anticentrosome drug that inhibits proliferation, at least in part, by disrupting centrosome-mediated MT assembly during mitosis.
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Affiliation(s)
- Michael A DiMaio
- Department of Biology and Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180, USA
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Rogers MA, Wright AJ, Marangoni AG. Nanostructuring fiber morphology and solvent inclusions in 12-hydroxystearic acid / canola oil organogels. Curr Opin Colloid Interface Sci 2009. [DOI: 10.1016/j.cocis.2008.02.004] [Citation(s) in RCA: 114] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Rogers MA, Wright AJ, Marangoni AG. Crystalline stability of self-assembled fibrillar networks of 12-hydroxystearic acid in edible oils. Food Res Int 2008. [DOI: 10.1016/j.foodres.2008.07.012] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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10
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Tucker RP, Tran H, Gong Q. Neurogenesis and neurite outgrowth in the spinal cord of chicken embryos and in primary cultures of spinal neurons following knockdown of Class III beta tubulin with antisense morpholinos. PROTOPLASMA 2008; 234:97-101. [PMID: 18825486 DOI: 10.1007/s00709-008-0021-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2008] [Accepted: 08/30/2008] [Indexed: 05/26/2023]
Abstract
Microtubules are the primary cytoskeletal constituent of extending neurites. We used antisense morpholinos to knock down expression of neuron-specific Class III beta tubulin in the right half of the neural tube of chicken embryos in ovo. There was a significant (p < 0.01) reduction in the number of Class III beta tubulin immunostained interneurons 24 h following electroporation of the morpholinos when compared with the contralateral side of the neural tube. However, neural crest-derived sensory neurons labeled with the fluorescently tagged morpholinos developed distinct processes. Moreover, there was no significant difference in the number of interneurons labeled on either side of the neural tube with a second marker of developing neurons, anti-microtubule associated protein (MAP) 1b. Neural tubes were also excised and dissociated following antisense or control morpholino electroporation. The resulting neurons were cultured for 48 h and immunostained with anti-Class III beta tubulin and anti-MAP 1b. Neurons that had taken up the antisense morpholino had significantly shorter neurites (p < 0.01) than neurons from the same neural tubes that did not; they also had significantly shorter neurites (p < 0.05) than labeled neurons from neural tubes electroporated with a control morpholino. Thus, normal expression of Class III beta tubulin may not be necessary for neurogenesis in the early avian spinal cord in situ, but is required for neurite outgrowth in vitro.
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Affiliation(s)
- Richard P Tucker
- Department of Cell Biology and Human Anatomy, University of California at Davis, Davis, CA 95616-8643, USA.
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11
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Rogers MA, Wright AJ, Marangoni AG. Engineering the oil binding capacity and crystallinity of self-assembled fibrillar networks of in edible oils. SOFT MATTER 2008; 4:1483-1490. [PMID: 32907115 DOI: 10.1039/b803299h] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The crystallinity and oil binding capacity of 12-hydroxystearic acid (12HSA)-vegetable oil organogels was modified by changing the post-crystallization annealing temperature from 5 °C to 30 °C for 24 h. The gels stored at 5 °C had a highly branched crystalline structure with small uniform pores, as determined by cryo-scanning electron microscopy. Large T2proton relaxation peaks at 50 to 70 ms determined by pulse nuclear magnetic resonance (pNMR) suggested the presence of highly immobilized oil at 5 °C. When the gels were stored at 30 °C, longer fibers and a less branched network were observed. At 30 °C, the 12HSA network's crystallinity was enhanced with fewer inclusions of liquid oil as determined by pNMR. When the gels were stored at 30 °C, a significantly shorter T2 relaxation peak was observed. The increased crystallinity, at 30 °C, was attributed to a reduction in bulk supersaturation, resulting in a very high crystallographic mismatch nucleation barrier (ΔG*) which favored one-dimensional fiber growth. However, at a lower crystallization temperature of 5 °C, there is an increase in the supersaturation and hence the crystallographic mismatch barrier is significantly lower, increasing fiber tip branching. The nucleation-growth-branching-growth model for self-assembled fibrillar networks explains the differences in crystallinity, pore size and oil syneresis observed for the 12HSA-vegetable oil organogels. It was found that the gels stored at 30 °C syneresised 1.35 times faster than the gels stored at 5 °C. Furthermore, the change in the T2 relaxations and the ratio of the complex viscosity/pore radius were 1.35 and 1.30 respectively.
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Affiliation(s)
- Michael A Rogers
- Department of Food Science, University of Guelph, Guelph, ON, Canada, N1G2W1.
| | - Amanda J Wright
- Department of Human Health & Nutritional Science, University of Guelph, Guelph, ON, Canada, N1G2W1
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12
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Patel-Hett S, Richardson JL, Schulze H, Drabek K, Isaac NA, Hoffmeister K, Shivdasani RA, Bulinski JC, Galjart N, Hartwig JH, Italiano JE. Visualization of microtubule growth in living platelets reveals a dynamic marginal band with multiple microtubules. Blood 2008; 111:4605-16. [PMID: 18230754 PMCID: PMC2343595 DOI: 10.1182/blood-2007-10-118844] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2007] [Accepted: 01/13/2008] [Indexed: 01/23/2023] Open
Abstract
The marginal band of microtubules maintains the discoid shape of resting blood platelets. Although studies of platelet microtubule coil structure conclude that it is composed of a single microtubule, no investigations of its dynamics exist. In contrast to previous studies, permeabilized platelets incubated with GTP-rhodamine-tubulin revealed tubulin incorporation at 7.9 (+/- 1.9) points throughout the coil, and anti-EB1 antibodies stained 8.7 (+/- 2.0) sites, indicative of multiple free microtubules. To pursue this result, we expressed the microtubule plus-end marker EB3-GFP in megakaryocytes and examined its behavior in living platelets released from these cells. Time-lapse microscopy of EB3-GFP in resting platelets revealed multiple assembly sites within the coil and a bidirectional pattern of assembly. Consistent with these findings, tyrosinated tubulin, a marker of newly assembled microtubules, localized to resting platelet microtubule coils. These results suggest that the resting platelet marginal band contains multiple highly dynamic microtubules of mixed polarity. Analysis of microtubule coil diameters in newly formed resting platelets indicates that microtubule coil shrinkage occurs with aging. In addition, activated EB3-GFP-expressing platelets exhibited a dramatic increase in polymerizing microtubules, which travel outward and into filopodia. Thus, the dynamic microtubules associated with the marginal band likely function during both resting and activated platelet states.
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Affiliation(s)
- Sunita Patel-Hett
- Translational Medicine Division, Brigham and Women's Hospital, Boston, MA 02115, USA
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13
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Matsuda Y, Sahara K, Yasukochi Y, Yamashiki N. Detection of gamma-tubulin in spermatogonial cells of Bombyx mori (Lepidoptera) and Chortophaga viridifasciata (Orthoptera). Zoolog Sci 2008; 24:781-6. [PMID: 18217484 DOI: 10.2108/zsj.24.781] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We detected a putative gamma-tubulin gene in silico and detected BACs containing the gene from a Bombyx mori BAC library. BAC-FISH mapping revealed that the gene is located on chromosome 5. To observe the distribution of gamma-tubulin, we employed antibodies against mammalian gamma-tubulin peptides. Western blot analysis disclosed a band very similar in size to gamma-tubulin protein in other species (approximately 48 kDa). In mitotic metaphase of B. mori spermatogonial cells, gamma-tubulin is exclusively localized in the spindle poles, where the centrosomes occur. We applied the same system to the grasshopper Chortophaga viridifasciata, as a representative of insect orders in which the gamma-tubulin distribution had not previously been studied. Gamma-tubulin was also found in the spindle poles during metaphase of spermatogonial cells in the grasshopper.
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Affiliation(s)
- Yumi Matsuda
- Laboratory of Developmental Biology, Rakuno Gakuen University, Ebetsu 069-8501, Japan
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14
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Kollman JM, Zelter A, Muller EGD, Fox B, Rice LM, Davis TN, Agard DA. The structure of the gamma-tubulin small complex: implications of its architecture and flexibility for microtubule nucleation. Mol Biol Cell 2007; 19:207-15. [PMID: 17978090 DOI: 10.1091/mbc.e07-09-0879] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The gamma-tubulin small complex (gamma-TuSC) is an evolutionarily conserved heterotetramer essential for microtubule nucleation. We have determined the structure of the Saccharomyces cerevisiae gamma-TuSC at 25-A resolution by electron microscopy. gamma-TuSC is Y-shaped, with an elongated body connected to two arms. Gold labeling showed that the two gamma-tubulins are located in lobes at the ends of the arms, and the relative orientations of the other gamma-TuSC components were determined by in vivo FRET. The structures of different subpopulations of gamma-TuSC indicate flexibility in the connection between a mobile arm and the rest of the complex, resulting in variation of the relative positions and orientations of the gamma-tubulins. In all of the structures, the gamma-tubulins are distinctly separated, a configuration incompatible with the microtubule lattice. The separation of the gamma-tubulins in isolated gamma-TuSC likely plays a role in suppressing its intrinsic microtubule-nucleating activity, which is relatively weak until the gamma-TuSC is incorporated into higher order complexes or localized to microtubule-organizing centers. We propose that further movement of the mobile arm is required to bring the gamma-tubulins together in microtubule-like interactions, and provide a template for microtubule growth.
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Affiliation(s)
- Justin M Kollman
- Department of Biochemistry and Biophysics and the Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA
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15
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Rogers MA, Smith AK, Wright AJ, Marangoni AG. A Novel Cryo-SEM Technique for Imaging Vegetable Oil Based Organogels. J AM OIL CHEM SOC 2007. [DOI: 10.1007/s11746-007-1122-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Suzaki E, Nomura R, Horio T, Mineyuki Y, Kataoka K. gamma-Tubulin-like molecules in the mouse duodenal epithelium. Histochem Cell Biol 2007; 128:175-82. [PMID: 17562068 DOI: 10.1007/s00418-007-0299-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/18/2007] [Indexed: 11/25/2022]
Abstract
A mouse monoclonal antibody (G9, Horio et al. in Cell Motil Cytoskel 44:284-295, 1999) that was raised against the gamma-tubulin from a fission yeast, Schizosaccharomyces pombe, showed a unique staining in the mouse small intestine. Similar to another anti-gamma-tubulin antibody that is commercially available, G9 showed typical dot-like staining corresponding to the microtubule-organizing center in the free cells of the epithelium and the connective tissue under it. In addition, G9 stained the cell-cell contacts in the epithelium. This stained region was not bicellular but tricellular junctions of the enterocytes. This staining was unique to G9 and was diminished on the sample of the mouse small intestine, which had lost most of its filamentous microtubules through the preparation process. The tricellular junction is thought to be the weakest point of the epithelial barrier, and no other junctional structures have been identified except for the central sealing elements extending from the tight junctions between the two cells. Our results suggest the existence of a new molecule underlying the tricellular junctions, which may relate to gamma-tubulin and the microtubules.
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Affiliation(s)
- Etsuko Suzaki
- Department of Pharmaceutical Sciences, School of Pharmacy, Shujitsu University, 1-6-1 Nishikawahara, Okayama, 703-8516, Japan.
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Sánchez-Alcázar JA, Rodríguez-Hernández A, Cordero MD, Fernández-Ayala DJM, Brea-Calvo G, Garcia K, Navas P. The apoptotic microtubule network preserves plasma membrane integrity during the execution phase of apoptosis. Apoptosis 2007; 12:1195-208. [PMID: 17245640 DOI: 10.1007/s10495-006-0044-6] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
It has recently been shown that the microtubule cytoskeleton is reformed during the execution phase of apoptosis. We demonstrate that this microtubule reformation occurs in many cell types and under different apoptotic stimuli. We confirm that the apoptotic microtubule network possesses a novel organization, whose nucleation appears independent of conventional gamma-tubulin ring complex containing structures. Our analysis suggests that microtubules are closely associated with the plasma membrane, forming a cortical ring or cellular "cocoon". Concomitantly other components of the cytoskeleton, such as actin and cytokeratins disassemble. We found that colchicine-mediated disruption of apoptotic microtubule network results in enhanced plasma membrane permeability and secondary necrosis, suggesting that the reformation of a microtubule cytoskeleton plays an important role in preserving plasma membrane integrity during apoptosis. Significantly, cells induced to enter apoptosis in the presence of the pan-caspase inhibitor z-VAD, nevertheless form microtubule-like structures suggesting that microtubule formation is not dependent on caspase activation. In contrast we found that treatment with EGTA-AM, an intracellular calcium chelator, prevents apoptotic microtubule network formation, suggesting that intracellular calcium may play an essential role in the microtubule reformation. We propose that apoptotic microtubule network is required to maintain plasma membrane integrity during the execution phase of apoptosis.
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Affiliation(s)
- José A Sánchez-Alcázar
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide-CSIC, Carretera de Utrera Km 1, Sevilla, 41013, Spain.
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18
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Joachimiak E, Pucciarelli S, Barchetta S, Ballarini P, Kaczanowska J, Miceli C. Cell Cycle-dependent Expression of γ-Tubulin in the Amicronuclear Ciliate Tetrahymena pyriformis. Protist 2007; 158:39-50. [PMID: 17023214 DOI: 10.1016/j.protis.2006.08.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2006] [Accepted: 08/01/2006] [Indexed: 10/24/2022]
Abstract
In ciliates, different microtubular structures are nucleated from diverse Microtubule Organizing Centers (MTOCs). gamma-Tubulin is a tubulin superfamily member that plays an essential role in microtubule nucleation at the MTOCs. However, little is known about mechanisms regulating the activity of gamma-tubulin on different MTOCs and during the cell cycle. In Tetrahymena thermophila, the alpha- and beta-tubulin expression is regulated mainly at the transcriptional level, and changes in the ratio of polymerized/unpolymerized tubulin dimers lead to an increase or decrease of alpha- and beta-tubulin transcription. This study deals with the characterization of gamma-tubulin in the amicronuclear ciliate Tetrahymena pyriformis. Sequence analysis revealed some specific substitutions in nucleotide-binding loops characteristic of the Tetrahymena genus and putative conserved phosphorylation sites located on the external surface of the gamma-tubulin molecule. gamma-Tubulin expression during the cell cycle, in the presence of microtubular poisons and after deciliation, was also characterized. We found that gamma-tubulin mRNA levels are correlated with basal body proliferation and gamma-tubulin nuclear localization. We also found that gamma-tubulin expression changes during anti-microtubular drugs treatment, but does not changes during reciliation. These findings suggest a relationship between the level of unpolymerized tubulin dimers and gamma-tubulin transcription.
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Affiliation(s)
- Ewa Joachimiak
- Department of Molecular, Cellular and Animal Biology, University of Camerino, Camerino 62032, v. Camerini 2, Italy
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Maas C, Tagnaouti N, Loebrich S, Behrend B, Lappe-Siefke C, Kneussel M. Neuronal cotransport of glycine receptor and the scaffold protein gephyrin. ACTA ACUST UNITED AC 2006; 172:441-51. [PMID: 16449194 PMCID: PMC2063653 DOI: 10.1083/jcb.200506066] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The dynamics of postsynaptic receptor scaffold formation and remodeling at inhibitory synapses remain largely unknown. Gephyrin, which is a multimeric scaffold protein, interacts with cytoskeletal elements and stabilizes glycine receptors (GlyRs) and individual subtypes of γ-aminobutyric acid A receptors at inhibitory postsynaptic sites. We report intracellular mobility of gephyrin transports packets over time. Gephyrin units enter and exit active synapses within several minutes. In addition to previous reports of GlyR–gephyrin interactions at plasma membranes, we show cosedimentation and coimmunoprecipitation of both proteins from vesicular fractions. Moreover, GlyR and gephyrin are cotransported within neuronal dendrites and further coimmunoprecipitate and colocalize with the dynein motor complex. As a result, the blockade of dynein function or dynein–gephyrin interaction, as well as the depolymerization of microtubules, interferes with retrograde gephyrin recruitment. Our data suggest a GlyR–gephyrin–dynein transport complex and support the concept that gephyrin–motor interactions contribute to the dynamic and activity-dependent rearrangement of postsynaptic GlyRs, a process thought to underlie the regulation of synaptic strength.
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Affiliation(s)
- Christoph Maas
- Zentrum für Molekulare Neurobiologie Hamburg, Universität Hamburg, D-20251 Hamburg, Germany
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Steet R, Kornfeld S. COG-7-deficient Human Fibroblasts Exhibit Altered Recycling of Golgi Proteins. Mol Biol Cell 2006; 17:2312-21. [PMID: 16510524 PMCID: PMC1446086 DOI: 10.1091/mbc.e05-08-0822] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Recently, we reported that two siblings presenting with the clinical syndrome congenital disorders of glycosylation (CDG) have mutations in the gene encoding Cog7p, a member of the conserved oligomeric Golgi (COG) complex. In this study, we analyzed the localization and trafficking of multiple Golgi proteins in patient fibroblasts under a variety of conditions. Although the immunofluorescent staining pattern of several Golgi proteins was indistinguishable from normal, the staining of endoplasmic reticulum (ER)-Golgi intermediate compartment (ERGIC)-53 and the vesicular-soluble N-ethylmaleimide-sensitive factor attachment protein receptors GS15 and GS28 was abnormal, and the steady-state level of GS15 was greatly decreased. Retrograde transport of multiple Golgi proteins to the ER in patient fibroblasts via brefeldin A-induced tubules was significantly slower than occurs in normal fibroblasts, whereas anterograde protein trafficking was much less affected. After prolonged treatment with brefeldin A, several Golgi proteins were detected in clusters that colocalize with the microtubule-organizing center in patient cells. All of these abnormalities were normalized in COG7-corrected patient fibroblasts. These results serve to better define the role of the COG complex in facilitating protein trafficking between the Golgi and ER and provide a diagnostic framework for the identification of CDG defects involving trafficking proteins.
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Affiliation(s)
- Richard Steet
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.
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21
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Abstract
Centrosomes are dynamic organelles involved in many aspects of cell function and growth. Centrosomes act as microtubule organizing centers, and provide a site for concerted regulation of cell cycle progression. While there is diversity in microtubule organizing center structure among eukaryotes, many centrosome components, such as centrin, are conserved. Experimental analysis has provided an outline to describe centrosome duplication, and numerous centrosome components have been identified. Even so, more work is needed to provide a detailed understanding of the interactions between centrosome components and their roles in centrosome function and duplication. Precise duplication of centrosomes once during each cell cycle ensures proper mitotic spindle formation and chromosome segregation. Defects in centrosome duplication or function are linked to human diseases including cancer. Here we provide a multifaceted look at centrosomes with a detailed summary of the centrosome cycle.
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Goswami C, Dreger M, Otto H, Schwappach B, Hucho F. Rapid disassembly of dynamic microtubules upon activation of the capsaicin receptor TRPV1. J Neurochem 2005; 96:254-66. [PMID: 16336230 DOI: 10.1111/j.1471-4159.2005.03551.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The transmission of pain signalling involves the cytoskeleton, but mechanistically this is poorly understood. We recently demonstrated that the capsaicin receptor TRPV1, a non-selective cation channel expressed by nociceptors that is capable of detecting multiple pain-producing stimuli, directly interacts with the tubulin cytoskeleton. We hypothesized that the tubulin cytoskeleton is a downstream effector of TRPV1 activation. Here we show that activation of TRPV1 results in the rapid disassembly of microtubules, but not of the actin or neurofilament cytoskeletons. TRPV1 activation mainly affects dynamic microtubules that contain tyrosinated tubulins, whereas stable microtubules are apparently unaffected. The C-terminal fragment of TRPV1 exerts a stabilizing effect on microtubules when over-expressed in F11 cells. These findings suggest that TRPV1 activation may contribute to cytoskeleton remodelling and so influence nociception.
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Affiliation(s)
- C Goswami
- Freie Universität Berlin, Institut für Chemie/Biochemie, Berlin, Germany
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Yuba-Kubo A, Kubo A, Hata M, Tsukita S. Gene knockout analysis of two gamma-tubulin isoforms in mice. Dev Biol 2005; 282:361-73. [PMID: 15893303 DOI: 10.1016/j.ydbio.2005.03.031] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2004] [Revised: 03/14/2005] [Accepted: 03/16/2005] [Indexed: 11/19/2022]
Abstract
Gamma-tubulin regulates the nucleation of microtubules, but knowledge of its functions in vivo is still fragmentary. Here, we report the identification of two closely related gamma-tubulin isoforms, TUBG1 and TUBG2, in mice, and the generation of TUBG1- and TUBG2-deficient mice. TUBG1 was expressed ubiquitously, whereas TUBG2 was primarily detected in the brain. The development of TUBG1-deficient (Tubg1-/-) embryos stopped at the morula/blastocyst stages due to a characteristic mitotic arrest: the mitotic spindle was highly disorganized, and disorganized spindles showed one or two pole-like foci of bundled MTs that were surrounded by condensed chromosomes. TUBG2 was expressed in blastocysts, but could not rescue the TUBG1 deficiency. By contrast, TUBG2-deficient (Tubg2-/-) mice were born, grew, and intercrossed normally. In the brain of wild-type mice, TUBG2 was expressed in approximately the same amount as TUBG1, but no histological abnormalities were found in the Tubg2-/- brain. These findings indicated that TUBG1 and TUBG2 are not functionally equivalent in vivo, that TUBG1 corresponds to conventional gamma-tubulin, and that TUBG2 may have some unidentified function in the brain.
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Affiliation(s)
- Akiko Yuba-Kubo
- Solution Oriented Research for Science and Technology, Japan Science and Technology Corporation, Sakyo-ku, Kyoto 606-8501, Japan
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24
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Huang X, Terech P, Raghavan SR, Weiss RG. Kinetics of 5alpha-cholestan-3beta-yl N-(2-naphthyl)carbamate/n-alkane organogel formation and its influence on the fibrillar networks. J Am Chem Soc 2005; 127:4336-44. [PMID: 15783215 DOI: 10.1021/ja0426544] [Citation(s) in RCA: 227] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The kinetics and mode of nucleation and growth of fibers by 5alpha-cholestan-3beta-yl N-(2-naphthyl)carbamate (CNC), a low-molecular-mass organogelator (LMOG), in n-octane and n-dodecane have been investigated as their sols were transformed isothermally to organogels. The kinetics has been followed in detail by circular dichroism, fluorescence, small-angle neutron scattering, and rheological methods. When treated according to Avrami theory, kinetic data from the four methods are self-consistent and describe a gelation process involving one-dimensional growth and "instantaneous nucleation". As expected from this growth model, polarized optical micrographs of the self-assembled fibrillar networks (SAFINs) show fibrous aggregates. However, their size and appearance change abruptly from spherulitic to rodlike as temperature is increased. This morphological change is attended by corresponding excursions in static and kinetic CD, fluorescence and rheological data. Furthermore, the rheological measurements reveal an unusual linear increase in viscoelastic moduli in the initial stages of self-assembly. Each of the methods employed becomes sensitive to changes of the system at different stages of the transformation from single molecules of the LMOG to their eventual SAFINs. This study also provides a methodology for investigating aggregation phenomena of some other self-assembling systems, including those of biological and physiological importance.
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Affiliation(s)
- Xiao Huang
- Department of Chemistry, Georgetown University, 37th and O Streets, NW, Washington, D.C. 20057-1227, USA
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25
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Sumara I, Giménez-Abián JF, Gerlich D, Hirota T, Kraft C, de la Torre C, Ellenberg J, Peters JM. Roles of polo-like kinase 1 in the assembly of functional mitotic spindles. Curr Biol 2005; 14:1712-22. [PMID: 15458642 DOI: 10.1016/j.cub.2004.09.049] [Citation(s) in RCA: 263] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2004] [Revised: 08/26/2004] [Accepted: 08/31/2004] [Indexed: 11/20/2022]
Abstract
BACKGROUND The stable association of chromosomes with both poles of the mitotic spindle (biorientation) depends on spindle pulling forces. These forces create tension across sister kinetochores and are thought to stabilize microtubule-kinetochore interactions and to silence the spindle checkpoint. Polo-like kinase 1 (Plk1) has been implicated in regulating centrosome maturation, mitotic entry, sister chromatid cohesion, the anaphase-promoting complex/cyclosome (APC/C), and cytokinesis, but it is unknown if Plk1 controls chromosome biorientation. RESULTS We have analyzed Plk1 functions in synchronized mammalian cells by RNA interference (RNAi). Plk1-depleted cells enter mitosis after a short delay, accumulate in a preanaphase state, and subsequently often die by apoptosis. Spindles in Plk1-depleted cells lack focused poles and are not associated with centrosomes. Chromosomes attach to these spindles, but the checkpoint proteins Mad2, BubR1, and CENP-E are enriched at many kinetochores. When Plk1-depleted cells are treated with the Aurora B inhibitor Hesperadin, which silences the spindle checkpoint by stabilizing microtubule-kinetochore interactions, cells degrade APC/C substrates and exit mitosis without chromosome segregation and cytokinesis. Experiments with monopolar spindles that are induced by the kinesin inhibitor Monastrol indicate that Plk1 is required for the assembly of spindles that are able to generate poleward pulling forces. CONCLUSIONS Our results imply that Plk1 is not essential for mitotic entry and APC/C activation but is required for proper spindle assembly and function. In Plk1-depleted cells spindles may not be able to create enough tension across sister kinetochores to stabilize microtubule-kinetochore interactions and to silence the spindle checkpoint.
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Affiliation(s)
- Izabela Sumara
- Research Institute of Molecular Pathology, Dr. Bohr-Gasse 7, 1030 Vienna, Austria
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26
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Horio T, Kimura N, Basaki A, Tanaka Y, Noguchi T, Akashi T, Tanaka K. Molecular and structural characterization of the spindle pole bodies in the fission yeast Schizosaccharomyces japonicus var japonicus. Yeast 2002; 19:1335-50. [PMID: 12402243 DOI: 10.1002/yea.921] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The structure and localization of the microtubule organization centres (MTOCs) of the fission yeast Schizosaccharomyces japonicus var. japonicus were examined by fluorescence microscopy and electron microscopy. Spindle pole bodies (SPBs), which are the fungal equivalent of centrosomes, of Sz. japonicus were visualized by immunofluorescent staining using a monoclonal anti-gamma-tubulin antibody. The behaviour of the SPBs during the cell cycle mostly coincided with previous reports on the most widely used fission yeast Schizosaccharomyces pombe. We cloned the gamma-tubulin gene from Sz. japonicus by PCR using redundant sets of primers corresponding to conserved regions of known gamma-tubulins. The predicted amino acid sequence of Sz. japonicus gamma-tubulin was most similar to the Sz. pombe gamma-tubulin. Under the electron microscope, the SPBs of Sz. japonicus were detected as electron-dense multilayered structures located just outside the nuclear envelope. The SPBs of Sz. japonicus were composed of three electron-dense layers and were surrounded by fuzzy material. Each layer showed structural changes according to the progression of the cell cycle. In mitotic cells, the SPBs were located on the fenestrae of the nuclear envelopes through which the mitotic spindle microtubules ran into the nucleoplasm. Our results show that Sz. japonicus is a very potent and attractive organism for the investigation of the microtubule nucleation system and morphogenesis in yeasts. The Accession No. for the nucleotide sequence of the Sz. japonicus gtb1(+) gene is AF159163.
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Affiliation(s)
- Tetsuya Horio
- Department of Food Microbiology, Tokushima University School of Medicine, 3-18-15 Kuramoto, Tokushima 770-8503, Japan.
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27
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Affiliation(s)
- Y Ovechkina
- Department of Molecular Genetics, Ohio State University, Columbus, Ohio 43210, USA
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McClinton RS, Chandler JS, Callis J. cDNA isolation, characterization, and protein intracellular localization of a katanin-like p60 subunit from Arabidopsis thaliana. PROTOPLASMA 2001; 216:181-90. [PMID: 11732186 DOI: 10.1007/bf02673870] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Katanin, a heterodimeric protein with ATP-dependent microtubule-severing activity, localizes to the centrosome in animal cells. Widespread occurrence is suspected as several species contain homologs to the katanin p60 subunit. Recently we isolated an Arabidopsis thaliana cDNA with significant identity to the p60 subunit of sea urchin katanin. Like p60, the encoded protein is a member of the AAA superfamily of ATPases, containing the Walker ATP binding consensus and the signature AAA minimal consensus sequences within a single larger AAA/CAD amino acid motif. Phylogenetic analysis placed the encoded protein in the AAA subfamily of cytoskeleton-interactive proteins, where it formed a strongly supported clade with 4 other members identified as katanin p60 subunits. The clone was named AtKSS (Arabidopsis thaliana katanin-like protein small subunit). Western blots, performed using a polyclonal antibody raised against recombinant AtKSS, revealed AtKSS is present in protein extracts of all Arabidopsis organs examined. To evaluate potential interactions between AtKSS and the cytoskeleton, the intracellular localization of AtKSS was correlated with that of tubulin. AtKSS was found in perinuclear regions during interphase, surrounding the spindle poles during mitosis, but was absent from the preprophase band and phragmoplast microtubule arrays. These data support the thesis that AtKSS is an Arabidopsis homolog of the p60 subunit of katanin. Its cell cycle-dependent distribution is consistent with microtubule-severing activity, but additional studies will better define its role.
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Affiliation(s)
- R S McClinton
- Department of Biology, University of Louisiana at Lafayette, P.O. Box 42451, Lafayette, LA 70504-2451, USA
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29
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Takeoka A, Shimizu M, Horio T. Identification of an alpha-tubulin mutant of fission yeast from gamma-tubulin-interacting protein screening: genetic evidence for alpha-/gamma-tubulin interaction. J Cell Sci 2000; 113 Pt 24:4557-62. [PMID: 11082048 DOI: 10.1242/jcs.113.24.4557] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
gamma-Tubulin has been determined to be a central element of microtubule nucleation and, thus, indispensable for cellular organization of the microtubule. Utilizing the fact that human gamma-tubulin can function in the fission yeast Schizosaccharomyces pombe, we have generated a unique mutant screening procedure which can specifically select mutants of genes encoding gamma-tubulin-interacting proteins. One of the isolated mutants, cs76, turned out to carry a mutation in the alpha 1-tubulin gene (nda2(+)). This result suggests a direct interaction between the alpha- and gamma-tubulins. We located the mutation site in the nda2 gene and characterized the mutant phenotype. Our results demonstrate the importance of the alpha-/gamma-tubulin interaction in microtubule nucleation and should complement previous knowledge.
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Affiliation(s)
- A Takeoka
- Department of Food Microbiology, The University of Tokushima School of Medicine, Kuramoto, Tokushima 770-8503, Japan
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30
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Abstract
Recent data have revealed that the tubulin superfamily of proteins is much larger than was thought previously. Six distinct families within the tubulin superfamily have been discovered and more might await discovery. alpha-, beta- and gamma-tubulins are ubiquitous in eukaryotes. alpha- and beta-tubulins are the major components of microtubules, and gamma-tubulin plays a major role in the nucleation of microtubule assembly. delta- and epsilon-tubulins are widespread but not ubiquitous, and zeta-tubulin has been found so far only in kinetoplastid protozoa. delta-Tubulin has an important role in flagellar assembly in Chlamydomonas, but its role in other organisms is just beginning to be investigated, as are the functions of the recently discovered epsilon- and zeta-tubulins.
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Affiliation(s)
- B R Oakley
- Dept of Molecular Genetics, The Ohio State University, 484 W. 12th Ave, Columbus, OH 43210, USA.
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