Faculty Opinions recommendation of Reorganization of the microtubule array in prophase/prometaphase requires cytoplasmic dynein-dependent microtubule transport.

2002 ◽  
Author(s):  
Vladimir Rodionov
Keyword(s):  
Cytoplasmic Dynein ◽  
Microtubule Array ◽  
Microtubule Transport

Dynein and plus-end microtubule-dependent motors are associated with specialized Sertoli cell junction plaques (ectoplasmic specializations)

2000 ◽  
Vol 113 (12) ◽  
pp. 2167-2176
Author(s):  
J.A. Guttman ◽  
G.H. Kimel ◽  
A.W. Vogl
Keyword(s):  
Endoplasmic Reticulum ◽  
Sertoli Cell ◽  
Motor Proteins ◽  
Ultrastructural Level ◽  
Cytoplasmic Dynein ◽  
Cell Junction ◽  
Cytoplasmic Face ◽  
Microtubule Transport ◽  
Type Motor

The mechanism responsible for spermatid translocation in the mammalian seminiferous epithelium was proposed to be the microtubule-based transport of specialized junction plaques (ectoplasmic specializations) that occur in Sertoli cell regions attached to spermatid heads. These plaques each consist of a cistern of endoplasmic reticulum, a layer of actin filaments and the adjacent plasma membrane. It is predicted that motor proteins function to move the junction plaques, and hence the attached spermatids, first towards the base and then back to the apex of the epithelium, along microtubules. If this hypothesis is true, motor proteins should be associated with the cytoplasmic face of the endoplasmic reticulum component of ectoplasmic specializations. In addition, isolated junction plaques should support microtubule movement both in the plus and minus directions to account for the bidirectional translocation of spermatids in vivo. To determine if cytoplasmic dynein is localized to the endoplasmic reticulum of the plaques, perfusion-fixed rat testes were immunologically probed, at the ultrastructural level, for the intermediate chain of cytoplasmic dynein (IC74). In addition, testicular fractions enriched for spermatid/junction complexes were incubated with and without gelsolin, centrifuged and the supernatants compared, by western blot analysis, for Glucose Regulated Protein 94 (a marker for endoplasmic reticulum) and IC74. At the ultrastructural level, the probe for IC74 clearly labelled material associated with the cytoplasmic face of the endoplasmic reticulum component of the junction plaques. In the gelsolin experiments, both probes reacted more strongly with appropriate bands from the gelsolin-treated supernatants than with corresponding bands from controls. To determine if the junction plaques support microtubule transport in both directions, polarity-labelled microtubules were bound to isolated spermatid/junction complexes and then assessed for motility in the presence of ATP and testicular cytosol (2 mg/ml). Of 25 recorded motility events, 17 were in a direction consistent with a plus-end directed motor being present, and 8 were in the minus-end direction. The results are consistent with the conclusion that the junction plaques have the potential for moving along microtubules in both the plus and minus directions and that both a kinesin-type and a dynein-type motor may be associated with the junction plaques. The data also indicate that cytoplasmic dynein is localized to the cytoplasmic face of the endoplasmic reticulum component of the plaques.

scholarly journals A novel isoform of MAP4 organises the paraxial microtubule array required for muscle cell differentiation

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Binyam Mogessie ◽  
Daniel Roth ◽  
Zainab Rahil ◽  
Anne Straube
Keyword(s):  
Cell Differentiation ◽  
Cell Fusion ◽  
Muscle Cell ◽  
Cell Elongation ◽  
Myogenic Differentiation ◽  
Muscle Cells ◽  
Microtubule Array ◽  
Muscle Cell Differentiation ◽  
Microtubule Transport

The microtubule cytoskeleton is critical for muscle cell differentiation and undergoes reorganisation into an array of paraxial microtubules, which serves as template for contractile sarcomere formation. In this study, we identify a previously uncharacterised isoform of microtubule-associated protein MAP4, oMAP4, as a microtubule organising factor that is crucial for myogenesis. We show that oMAP4 is expressed upon muscle cell differentiation and is the only MAP4 isoform essential for normal progression of the myogenic differentiation programme. Depletion of oMAP4 impairs cell elongation and cell–cell fusion. Most notably, oMAP4 is required for paraxial microtubule organisation in muscle cells and prevents dynein- and kinesin-driven microtubule–microtubule sliding. Purified oMAP4 aligns dynamic microtubules into antiparallel bundles that withstand motor forces in vitro. We propose a model in which the cooperation of dynein-mediated microtubule transport and oMAP4-mediated zippering of microtubules drives formation of a paraxial microtubule array that provides critical support for the polarisation and elongation of myotubes.

Collective effects of yeast cytoplasmic dynein based microtubule transport

Soft Matter ◽  
2019 ◽  
Vol 15 (7) ◽  
pp. 1571-1581 ◽  
Author(s):  
Kunalika Jain ◽  
Neha Khetan ◽  
Chaitanya A. Athale
Keyword(s):  
Cytoplasmic Dynein ◽  
Collective Effects ◽  
Microtubule Transport

The directionality of microtubules (MTs) transported by a yeast dynein is affected by both MT lengths and motor densities due to collective effects.

scholarly journals Cytoplasmic Dynein and Dynactin Are Required for the Transport of Microtubules into the Axon

1998 ◽  
Vol 140 (2) ◽  
pp. 391-401 ◽  
Author(s):  
Fridoon J. Ahmad ◽  
Christophe J. Echeverri ◽  
Richard B. Vallee ◽  
Peter W. Baas
Keyword(s):  
Cell Body ◽  
Sympathetic Neurons ◽  
Motor Protein ◽  
Time Frame ◽  
Cytoplasmic Dynein ◽  
Microtubule Assembly ◽  
Cell Biol ◽  
Microtubule Transport ◽  
Cultured Sympathetic Neurons ◽  
Over Time

Previous work from our laboratory suggested that microtubules are released from the neuronal centrosome and then transported into the axon (Ahmad, F.J., and P.W. Baas. 1995. J. Cell Sci. 108: 2761–2769). In these studies, cultured sympathetic neurons were treated with nocodazole to depolymerize most of their microtubule polymer, rinsed free of the drug for a few minutes to permit a burst of microtubule assembly from the centrosome, and then exposed to nanomolar levels of vinblastine to suppress further microtubule assembly from occurring. Over time, the microtubules appeared first near the centrosome, then dispersed throughout the cytoplasm, and finally concentrated beneath the periphery of the cell body and within developing axons. In the present study, we microinjected fluorescent tubulin into the neurons at the time of the vinblastine treatment. Fluorescent tubulin was not detected in the microtubules over the time frame of the experiment, confirming that the redistribution of microtubules observed with the experimental regime reflects microtubule transport rather than microtubule assembly. To determine whether cytoplasmic dynein is the motor protein that drives this transport, we experimentally increased the levels of the dynamitin subunit of dynactin within the neurons. Dynactin, a complex of proteins that mediates the interaction of cytoplasmic dynein and its cargo, dissociates under these conditions, resulting in a cessation of all functions of the motor tested to date (Echeverri, C.J., B.M. Paschal, K.T. Vaughan, and R.B. Vallee. 1996. J. Cell Biol. 132: 617–633). In the presence of excess dynamitin, the microtubules did not show the outward progression but instead remained near the centrosome or dispersed throughout the cytoplasm. On the basis of these results, we conclude that cytoplasmic dynein and dynactin are essential for the transport of microtubules from the centrosome into the axon.

scholarly journals Interactions and regulation of molecular motors in Xenopus melanophores

2002 ◽  
Vol 156 (5) ◽  
pp. 855-865 ◽  
Author(s):  
Steven P. Gross ◽  
M. Carolina Tuma ◽  
Sean W. Deacon ◽  
Anna S. Serpinskaya ◽  
Amy R. Reilein ◽  
...  
Keyword(s):  
Molecular Motors ◽  
Cytoplasmic Dynein ◽  
Model System ◽  
Transport Systems ◽  
Myosin V ◽  
Down Regulation ◽  
Microtubule Motors ◽  
Outward Transport ◽  
Microtubule Transport ◽  
Cellular Components

Many cellular components are transported using a combination of the actin- and microtubule-based transport systems. However, how these two systems work together to allow well-regulated transport is not clearly understood. We investigate this question in the Xenopus melanophore model system, where three motors, kinesin II, cytoplasmic dynein, and myosin V, drive aggregation or dispersion of pigment organelles called melanosomes. During dispersion, myosin V functions as a “molecular ratchet” to increase outward transport by selectively terminating dynein-driven minus end runs. We show that there is a continual tug-of-war between the actin and microtubule transport systems, but the microtubule motors kinesin II and dynein are likely coordinated. Finally, we find that the transition from dispersion to aggregation increases dynein-mediated motion, decreases myosin V–mediated motion, and does not change kinesin II–dependent motion. Down-regulation of myosin V contributes to aggregation by impairing its ability to effectively compete with movement along microtubules.

scholarly journals Reorganization of the microtubule array in prophase/prometaphase requires cytoplasmic dynein-dependent microtubule transport

2002 ◽  
Vol 158 (6) ◽  
pp. 997-1003 ◽  
Author(s):  
Nasser M. Rusan ◽  
U. Serdar Tulu ◽  
Carey Fagerstrom ◽  
Patricia Wadsworth
Keyword(s):  
Nuclear Envelope ◽  
Mitotic Spindle ◽  
Myosin Ii ◽  
Somatic Cells ◽  
Cytoplasmic Dynein ◽  
Nuclear Envelope Breakdown ◽  
Microtubule Transport ◽  
Spindle Microtubules ◽  
Peripheral Cytoplasm ◽  
Stimulation Of

When mammalian somatic cells enter mitosis, a fundamental reorganization of the Mt cytoskeleton occurs that is characterized by the loss of the extensive interphase Mt array and the formation of a bipolar mitotic spindle. Microtubules in cells stably expressing GFP–α-tubulin were directly observed from prophase to just after nuclear envelope breakdown (NEBD) in early prometaphase. Our results demonstrate a transient stimulation of individual Mt dynamic turnover and the formation and inward motion of microtubule bundles in these cells. Motion of microtubule bundles was inhibited after antibody-mediated inhibition of cytoplasmic dynein/dynactin, but was not inhibited after inhibition of the kinesin-related motor Eg5 or myosin II. In metaphase cells, assembly of small foci of Mts was detected at sites distant from the spindle; these Mts were also moved inward. We propose that cytoplasmic dynein-dependent inward motion of Mts functions to remove Mts from the cytoplasm at prophase and from the peripheral cytoplasm through metaphase. The data demonstrate that dynamic astral Mts search the cytoplasm for other Mts, as well as chromosomes, in mitotic cells.

scholarly journals A Combinatorial MAP Code Dictates Polarized Microtubule Transport

2019 ◽  
Author(s):  
Brigette Y. Monroy ◽  
Tracy C. Tan ◽  
Janah May Oclaman ◽  
Jisoo S. Han ◽  
Sergi Simo ◽  
...  
Keyword(s):  
Molecular Motors ◽  
Cytoplasmic Dynein ◽  
Directed Movement ◽  
Microtubule Associated Proteins ◽  
In Vitro Reconstitution ◽  
Microtubule Transport ◽  
Associated Proteins ◽  
Transient Interactions ◽  
Intracellular Sorting

ABSTRACTMany eukaryotic cells distribute their intracellular components through asymmetrically regulated active transport driven by molecular motors along microtubule tracks. While intrinsic and extrinsic regulation of motor activity exists, what governs the overall distribution of activated motor-cargo complexes within cells remains unclear. Here, we utilize in vitro reconstitution of purified motor proteins and non-enzymatic microtubule-associated proteins (MAPs) to demonstrate that these MAPs exhibit distinct influences on the motility of the three main classes of transport motors: kinesin-1, kinesin-3, and cytoplasmic dynein. Further, we dissect how combinations of MAPs affect motors, and reveal how transient interactions between MAPs and motors may promote these effects. From these data, we propose a general “MAP code” that has the capacity to strongly bias directed movement along microtubules and helps elucidate the intricate intracellular sorting observed in highly polarized cells such as neurons.

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