scholarly journals The roles of microtubule-based motor proteins in mitosis

2003 ◽  
Vol 162 (6) ◽  
pp. 1003-1016 ◽  
Author(s):  
Gohta Goshima ◽  
Ronald D. Vale
Keyword(s):  
Molecular Motors ◽  
Time Lapse ◽  
Cytoplasmic Dynein ◽  
Cell Type ◽  
Phenotypic Data ◽  
Alternative Pathways ◽  
Chromosome Alignment ◽  
Drosophila S2 Cells ◽  
Bipolar Spindles ◽  
Metazoan Cell

Kinesins and dyneins play important roles during cell division. Using RNA interference (RNAi) to deplete individual (or combinations of) motors followed by immunofluorescence and time-lapse microscopy, we have examined the mitotic functions of cytoplasmic dynein and all 25 kinesins in Drosophila S2 cells. We show that four kinesins are involved in bipolar spindle assembly, four kinesins are involved in metaphase chromosome alignment, dynein plays a role in the metaphase-to-anaphase transition, and one kinesin is needed for cytokinesis. Functional redundancy and alternative pathways for completing mitosis were observed for many single RNAi knockdowns, and failure to complete mitosis was observed for only three kinesins. As an example, inhibition of two microtubule-depolymerizing kinesins initially produced monopolar spindles with abnormally long microtubules, but cells eventually formed bipolar spindles by an acentrosomal pole-focusing mechanism. From our phenotypic data, we construct a model for the distinct roles of molecular motors during mitosis in a single metazoan cell type.

scholarly journals Microtubule-dependent Plus- and Minus End–directed Motilities Are Competing Processes for Nuclear Targeting of Adenovirus

1999 ◽  
Vol 144 (4) ◽  
pp. 657-672 ◽  
Author(s):  
Maarit Suomalainen ◽  
Michel Y. Nakano ◽  
Stephan Keller ◽  
Karin Boucke ◽  
Robert P. Stidwill ◽  
...  
Keyword(s):  
Time Lapse ◽  
Cytoplasmic Dynein ◽  
Target Cells ◽  
Cell Type ◽  
Nuclear Targeting ◽  
Directed Movement ◽  
Time Lapse Microscopy ◽  
Motor Activities ◽  
Organizing Center ◽  
Directed Motility

Adenovirus (Ad) enters target cells by receptor-mediated endocytosis, escapes to the cytosol, and then delivers its DNA genome into the nucleus. Here we analyzed the trafficking of fluorophore-tagged viruses in HeLa and TC7 cells by time-lapse microscopy. Our results show that native or taxol-stabilized microtubules (MTs) support alternating minus- and plus end–directed movements of cytosolic virus with elementary speeds up to 2.6 μm/s. No directed movement was observed in nocodazole-treated cells. Switching between plus- and minus end–directed elementary speeds at frequencies up to 1 Hz was observed in the periphery and near the MT organizing center (MTOC) after recovery from nocodazole treatment. MT-dependent motilities allowed virus accumulation near the MTOC at population speeds of 1–10 μm/min, depending on the cell type. Overexpression of p50/dynamitin, which is known to affect dynein-dependent minus end–directed vesicular transport, significantly reduced the extent and the frequency of minus end–directed migration of cytosolic virus, and increased the frequency, but not the extent of plus end–directed motility. The data imply that a single cytosolic Ad particle engages with two types of MT-dependent motor activities, the minus end– directed cytoplasmic dynein and an unknown plus end– directed activity.

scholarly journals Peroxisomes move by hitchhiking on early endosomes using the novel linker protein PxdA

2015 ◽  
Author(s):  
John Salogiannis ◽  
Martin J. Egan ◽  
Samara L. Reck-Peterson
Keyword(s):  
Molecular Motors ◽  
Intracellular Transport ◽  
Coiled Coil ◽  
Leading Edge ◽  
Time Lapse ◽  
Early Endosome ◽  
Organelle Transport ◽  
The Novel ◽  
Coiled Coil Region ◽  
Early Endosomes

Eukaryotic cells use microtubule-based intracellular transport for the delivery of many subcellular cargos, including organelles. The canonical view of organelle transport is that organelles directly recruit molecular motors via cargo-specific adaptors. In contrast to this view, we show here that peroxisomes move by hitchhiking on early endosomes, an organelle that directly recruits the transport machinery. Using the filamentous fungus Aspergillus nidulans we find that hitchhiking is mediated by a novel endosome-associated linker protein, PxdA. PxdA is required for normal distribution and long-range movement of peroxisomes, but not early endosomes or nuclei. Using simultaneous time-lapse imaging we find that early endosome-associated PxdA localizes to the leading edge of moving peroxisomes. We identify a coiled-coil region within PxdA that is necessary and sufficient for early endosome localization and peroxisome distribution and motility. These results present a new mechanism of microtubule-based organelle transport where peroxisomes hitchhike on early endosomes and identify PxdA as the novel linker protein required for this coupling.

scholarly journals The DHC1b (DHC2) Isoform of Cytoplasmic Dynein Is Required for Flagellar Assembly

1999 ◽  
Vol 144 (3) ◽  
pp. 473-481 ◽  
Author(s):  
Gregory J. Pazour ◽  
Bethany L. Dickert ◽  
George B. Witman
Keyword(s):  
Molecular Motors ◽  
Cell Movement ◽  
Intraflagellar Transport ◽  
Cytoplasmic Dynein ◽  
Cdna Clones ◽  
Western Blots ◽  
Heavy Chains ◽  
Different Types ◽  
Flagellar Assembly ◽  
Soluble Fractions

Dyneins are microtubule-based molecular motors involved in many different types of cell movement. Most dynein heavy chains (DHCs) clearly group into cytoplasmic or axonemal isoforms. However, DHC1b has been enigmatic. To learn more about this isoform, we isolated Chlamydomonas cDNA clones encoding a portion of DHC1b, and used these clones to identify a Chlamydomonas cell line with a deletion mutation in DHC1b. The mutant grows normally and appears to have a normal Golgi apparatus, but has very short flagella. The deletion also results in a massive redistribution of raft subunits from a peri-basal body pool (Cole, D.G., D.R. Diener, A.L. Himelblau, P.L. Beech, J.C. Fuster, and J.L. Rosenbaum. 1998. J. Cell Biol. 141:993–1008) to the flagella. Rafts are particles that normally move up and down the flagella in a process known as intraflagellar transport (IFT) (Kozminski, K.G., K.A. Johnson, P. Forscher, and J.L. Rosenbaum. 1993. Proc. Natl. Acad. Sci. USA. 90:5519–5523), which is essential for assembly and maintenance of flagella. The redistribution of raft subunits apparently occurs due to a defect in the retrograde component of IFT, suggesting that DHC1b is the motor for retrograde IFT. Consistent with this, Western blots indicate that DHC1b is present in the flagellum, predominantly in the detergent- and ATP-soluble fractions. These results indicate that DHC1b is a cytoplasmic dynein essential for flagellar assembly, probably because it is the motor for retrograde IFT.

scholarly journals The equatorial position of the metaphase plate ensures symmetric cell divisions

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Chia Huei Tan ◽  
Ivana Gasic ◽  
Sabina P Huber-Reggi ◽  
Damian Dudka ◽  
Marin Barisic ◽  
...  
Keyword(s):  
Spindle Assembly Checkpoint ◽  
Metaphase Plate ◽  
Spindle Assembly ◽  
Equatorial Position ◽  
Asymmetric Cell Divisions ◽  
Daughter Cells ◽  
Cell Divisions ◽  
Microtubule Stability ◽  
Chromosome Alignment ◽  
Metazoan Cell

Chromosome alignment in the middle of the bipolar spindle is a hallmark of metazoan cell divisions. When we offset the metaphase plate position by creating an asymmetric centriole distribution on each pole, we find that metaphase plates relocate to the middle of the spindle before anaphase. The spindle assembly checkpoint enables this centering mechanism by providing cells enough time to correct metaphase plate position. The checkpoint responds to unstable kinetochore–microtubule attachments resulting from an imbalance in microtubule stability between the two half-spindles in cells with an asymmetric centriole distribution. Inactivation of the checkpoint prior to metaphase plate centering leads to asymmetric cell divisions and daughter cells of unequal size; in contrast, if the checkpoint is inactivated after the metaphase plate has centered its position, symmetric cell divisions ensue. This indicates that the equatorial position of the metaphase plate is essential for symmetric cell divisions.

scholarly journals Actin Filaments and Myosin I Alpha Cooperate with Microtubules for the Movement of Lysosomes

2001 ◽  
Vol 12 (12) ◽  
pp. 4013-4029 ◽  
Author(s):  
Marie-Neige Cordonnier ◽  
Daniel Dauzonne ◽  
Daniel Louvard ◽  
Evelyne Coudrier
Keyword(s):  
Long Range ◽  
Molecular Motors ◽  
Actin Filaments ◽  
Fluorescent Protein ◽  
Time Lapse ◽  
Myosin I ◽  
Latrunculin A ◽  
Living Mouse ◽  
Green Fluorescent ◽  
First Time

An earlier report suggested that actin and myosin I alpha (MMIα), a myosin associated with endosomes and lysosomes, were involved in the delivery of internalized molecules to lysosomes. To determine whether actin and MMIα were involved in the movement of lysosomes, we analyzed by time-lapse video microscopy the dynamic of lysosomes in living mouse hepatoma cells (BWTG3 cells), producing green fluorescent protein actin or a nonfunctional domain of MMIα. In GFP-actin cells, lysosomes displayed a combination of rapid long-range directional movements dependent on microtubules, short random movements, and pauses, sometimes on actin filaments. We showed that the inhibition of the dynamics of actin filaments by cytochalasin D increased pauses of lysosomes on actin structures, while depolymerization of actin filaments using latrunculin A increased the mobility of lysosomes but impaired the directionality of their long-range movements. The production of a nonfunctional domain of MMIα impaired the intracellular distribution of lysosomes and the directionality of their long-range movements. Altogether, our observations indicate for the first time that both actin filaments and MMIα contribute to the movement of lysosomes in cooperation with microtubules and their associated molecular motors.

Dynamics of microtubules, motor proteins and 20S proteasomes during bovine oocyte IVM

2009 ◽  
Vol 21 (2) ◽  
pp. 304 ◽  
Author(s):  
S. E. Racedo ◽  
M. C. Branzini ◽  
D. Salamone ◽  
C. Wójcik ◽  
V. Y. Rawe ◽  
...  
Keyword(s):  
Atpase Activity ◽  
Molecular Motors ◽  
Motor Proteins ◽  
Chromatin Condensation ◽  
Germinal Vesicle ◽  
Cytoplasmic Dynein ◽  
Developmental Competence ◽  
Bovine Oocyte ◽  
Sodium Orthovanadate ◽  
Female Meiosis

The present study investigated the distribution of cytoplasmic dynein, dynactin and 20S proteasomes in oocytes isolated from small (<2 mm) and large (2–8 mm) follicles during IVM. Immediately after chromatin condensation (germinal vesicle (GV) breakdown), dynactin was closely associated with the chromatin and interacted with tubulin at the MI and MII spindles in oocytes recovered from large follicles. Dynactin showed perinuclear concentration. Dynein was homogeneously distributed in the cytoplasm of GV oocytes in both groups and was associated with the chromatin at the MI and MII spindle. The 20S proteasomes were found predominantly in the nucleus at the GV stage and were associated with the chromatin up to the MII stage in both groups of oocytes. The use of sodium orthovanadate, an inhibitor or phosphatase and ATPase activity, and nocodazole, a known disruptor of microtubules, affected the localisation of proteasomes in the meiotic stages. The results demonstrate the distinct dynamics of molecular motors and proteasomes during bovine oocyte IVM, their possible relationship with the developmental competence of the oocyte and the link between microtubules, their associated molecular motors and the transport of proteasomes during bovine female meiosis.

scholarly journals Ultrastructural analysis of intracellular membrane and microtubule behavior during mitosis of Drosophila S2 cells

2017 ◽  
Author(s):  
Anton Strunov ◽  
Lidiya V. Boldyreva ◽  
Evgeniya N. Andreyeva ◽  
Gera A. Pavlova ◽  
Julia V. Popova ◽  
...  
Keyword(s):  
Ultrastructural Level ◽  
S2 Cells ◽  
Intracellular Membrane ◽  
Genetic Determinants ◽  
Microtubule Organization ◽  
Mitotic Apparatus ◽  
Transmission Electron ◽  
Chromosome Alignment ◽  
Drosophila S2 Cells ◽  
Cell Mitosis

AbstractS2 cells are one of the most widely used Drosophila melanogaster cell lines for molecular dissection of mitosis using RNA interference (RNAi). However, a detailed and complete description of S2 cell mitosis at the ultrastructural level is still missing. Here, we analyzed by transmission electron microscopy (TEM) a random sample of 144 cells undergoing mitosis, focusing on intracellular membrane and microtubule (MT) behavior. This unbiased approach allowed us to discover that S2 cells exhibit a characteristic behavior of intracellular membranes, involving the formation of a quadruple nuclear membrane in early prometaphase and its disassembly during late prometaphase. After nuclear envelope disassembly, the mitotic apparatus becomes encased by a discontinuous network of ER membranes that associate with mitochondria preventing their diffusion into the spindle area. We also observed a peculiar metaphase spindle organization. We found that kinetochores with attached k-fibers are almost invariably associated with lateral MT bundles that can be either interpolar bundles or k-fibers connected to a different kinetochore. This spindle organization is likely to favor chromosome alignment at metaphase and subsequent segregation during anaphase. In summary, we describe several previously unknown features of membrane and microtubule organization during S2 cell mitosis. The genetic determinants of these mitotic features of can now be investigated using an RNAi-based approach, which is particularly easy and efficient in S2 cells

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