In vitro nucleation of microtubules from microtubule‐organizing center prepared from cellular slime mold

Kuriyama, Ryoko; Sato, Chikara; Fukui, Yoshio; Nishibayashi, Soryu

doi:10.1002/cm.970020306

Cited by 46 publications

(21 citation statements)

References 32 publications

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“…The second central motor kinesin in Dictyostelium, Kif9 (orphan), functions in a nuclear role completely separate from that of Kif6, to form at least part of the linkage between the interphase nucleus and the MTOC. Previous structural studies have described 4-to 5-nm-diameter fibers connecting the centrosome and nuclear envelope, and the tight linkage between these two objects is maintained even in the presence of MT poisons (29,44). Thus, it is unlikely that the MT system comprises the sole physical connection between the nucleus and MTOC.…”

Section: Discussionmentioning

confidence: 97%

“…By electron microscopy (EM), the MTOC of Dictyostelium appears as a cytoplasmic cube-shaped structure surrounded by amorphous dense material (39,44). EM, biochemical analyses, antibody labeling, and live-cell imaging studies have demonstrated that during interphase, the cytoplasmic MTOC is firmly and closely attached to the nucleus (28,29,44,48,49,63). Upon entry into mitosis, the MTOC duplicates during prophase and is brought to or into a fenestration of the nuclear envelope, and then it establishes an intranuclear bipolar spindle for division (39,53,64).…”

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confidence: 99%

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Microtubule-Nucleus Interactions in Dictyostelium discoideum Mediated by Central Motor Kinesins

et al. 2009

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Kinesins are a diverse superfamily of motor proteins that drive organelles and other microtubule-based movements in eukaryotic cells. These motors play important roles in multiple events during both interphase and cell division. Dictyostelium discoideum contains 13 kinesin motors, 12 of which are grouped into nine families, plus one orphan. Functions for 11 of the 13 motors have been previously investigated; we address here the activities of the two remaining kinesins, both isoforms with central motor domains. Kif6 (of the kinesin-13 family) appears to be essential for cell viability. The partial knockdown of Kif6 with RNA interference generates mitotic defects (lagging chromosomes and aberrant spindle assemblies) that are consistent with kinesin-13 disruptions in other organisms. However, the orphan motor Kif9 participates in a completely novel kinesin activity, one that maintains a connection between the microtubule-organizing center (MTOC) and nucleus during interphase. kif9 null cell growth is impaired, and the MTOC appears to disconnect from its normally tight nuclear linkage. Mitotic spindles elongate in a normal fashion in kif9 ؊ cells, but we hypothesize that this kinesin is important for positioning the MTOC into the nuclear envelope during prophase. This function would be significant for the early steps of cell division and also may play a role in regulating centrosome replication.Directed cell migration, organelle transport, and cell division involve fundamental motilities that are necessary for eukaryotic cell viability and function. Much of the force required for these motilities is generated through the cyclical interactions of motor proteins with the cell cytoskeleton. Microtubules (MTs) and actin filaments provide structural support and directional guides, and all eukaryotic organisms have diverse, often extensive families of motors that carry out different tasks. Functional studies have revealed that many of the motors work in combination with others, and that the individual deletion of a single motor activity often is insufficient to produce a defect that substantially impairs cell growth or function. The latter phenomenon is particularly evident in some organisms with simple motor families (14, 42). By contrasting homologous motor functions between simple and complex systems, we hope to learn the details of how each motor is custom-tuned for specific tasks.Dictyostelium discoideum is a compact amoeba that exhibits robust forms of motility common to nearly all animal cells, with speeds that frequently exceed corresponding rates in vertebrate cell models (25,33,54). Since Dictyostelium possesses a relatively small number of motor proteins (13 kinesin, 1 dynein, and 13 myosin isoforms [23,24,26]), it combines advantages of terrific cytology with straightforward molecular genetics and thus represents an excellent model to investigate individual and combined motor protein actions. To date, 11 of the 13 kinesin motors have been analyzed functionally (5,17,18,30,42,46,51,60). Only 1 of these 11 motor...

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Section: Discussionmentioning

confidence: 97%

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confidence: 99%

Microtubule-Nucleus Interactions in Dictyostelium discoideum Mediated by Central Motor Kinesins

et al. 2009

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“…which microtubules radiate (Roos, 1975a,b;Kuriyama et al, 1982;Euteneuer et al, 1998). The centrosome resides in the cytoplasm but is linked to the nucleus (Roos, 1975a;Omura & Fukui, 1985).…”

Section: (2) Centrosomal Events During Mitosis In Dictyostelium Discomentioning

confidence: 99%

“…). The acentriolar centrosome of D. discoideum is a cuboid structure which consists of a dense, three‐layered core surrounded by an amorphous corona from which microtubules radiate (Roos, 1975 a , b ; Kuriyama et al , ; Euteneuer et al , ). The centrosome resides in the cytoplasm but is linked to the nucleus (Roos, 1975 a ; Omura & Fukui, ).…”

Section: Introductionmentioning

confidence: 99%

Nucleocytoplasmic protein translocation during mitosis in the social amoebozoan Dictyostelium discoideum

O’Day

Budniak

2014

Biological Reviews

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Mitosis is a fundamental and essential life process. It underlies the duplication and survival of all cells and, as a result, all eukaryotic organisms. Since uncontrolled mitosis is a dreaded component of many cancers, a full understanding of the process is critical. Evolution has led to the existence of three types of mitosis: closed, open, and semi-open. The significance of these different mitotic species, how they can lead to a full understanding of the critical events that underlie the asexual duplication of all cells, and how they may generate new insights into controlling unregulated cell division remains to be determined. The eukaryotic microbe Dictyostelium discoideum has proved to be a valuable biomedical model organism. While it appears to utilize closed mitosis, a review of the literature suggests that it possesses a form of mitosis that lies in the middle between truly open and fully closed mitosis-it utilizes a form of semi-open mitosis. Here, the nucleocytoplasmic translocation patterns of the proteins that have been studied during mitosis in the social amoebozoan D. discoideum are detailed followed by a discussion of how some of them provide support for the hypothesis of semi-open mitosis.

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“…For example, the interphase MTOC in the cellular slime mold, Dictyostelium discoideum is a disc-shaped multilayered core embedded in an electron dense granular material [Roos, 19751. It is located next to the nucleus and can be isolated from cells as a coherent unit with the nucleus [Kuriyama et al, 19821. These nucleus associated bodies (NABs), although structurally distinct from mammalian centrosomes, appear to share the common functional property of initiating microtubule assembly in vitro [Kuriyama et al, 1982;Kuriyama, 19841. This suggests the presence of conserved functional elements among different types of MTOCs.…”

Section: Introductionmentioning

confidence: 99%

Heterogeneity of microtubule organizing center components as revealed by monoclonal antibodies to mammalian centrosomes and to nucleus‐associated bodies from Dictyostelium

Sellitto

Kimble

Kuriyama

1992

Cell Motil. Cytoskeleton

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The molecular composition of two morphologically distinct microtubule-organizing centers (MTOCs) was compared by probing with monoclonal antibodies raised against (i) nucleus-associated bodies (NABs) isolated in a complex with nuclei from the cellular slime mold Dictyostelium discoideum and (ii) mammalian mitotic spindles isolated from Chinese hamster ovary (CHO) cells. The staining patterns observed by immunofluorescence microscopy in whole CHO cells and Dictyostelium amoebae showed that the distribution of thirteen MTOC antigens is heterogeneous. Not all antibodies recognized the MTOC in both interphase and mitosis. Most of the anti-MTOC antibodies cross-reacted with other cellular organelles such as nuclei, Golgi apparatus-like aggregates and cytoskeletal elements. Two antibodies, CHO3 and AX3, recognized phosphorylated epitopes present in both mammalian centrosomes and Dictyostelium NABs. On immunoblots, most of the antibodies showed multiple bands, often of high molecular weight, indicating that the antigenic determinants are shared among different molecules. One antibody inhibited the regrowth of microtubules onto centrosomes in vitro after addition of exogenous tubulin to detergent-lysed CHO cells on coverslips; this antibody binds to an antigen(s) that might be essential for the microtubule-nucleating activity of centrosomes. These observations demonstrate that molecular components in different MTOCs exhibit a variety of distinct subcellular localizations and functional properties, and that some antigenic molecules have been conserved among morphologically distinct MTOCs.

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In vitro nucleation of microtubules from microtubule‐organizing center prepared from cellular slime mold

Cited by 46 publications

References 32 publications

Microtubule-Nucleus Interactions in Dictyostelium discoideum Mediated by Central Motor Kinesins

Microtubule-Nucleus Interactions in Dictyostelium discoideum Mediated by Central Motor Kinesins

Nucleocytoplasmic protein translocation during mitosis in the social amoebozoan Dictyostelium discoideum

Heterogeneity of microtubule organizing center components as revealed by monoclonal antibodies to mammalian centrosomes and to nucleus‐associated bodies from Dictyostelium

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