membrane traffic: Microtubule motor cycles and kinectin

1996 ◽  
Vol 54 ◽  
pp. 732-733
Author(s):  
Michael P. Sheetz
Keyword(s):  
Membrane Traffic ◽  
Growth Conditions ◽  
Cytoplasmic Dynein ◽  
Microtubule Motors ◽  
Transport Cycle ◽  
Microtubule Motor ◽  
Associated Proteins ◽  
The Many ◽  
Dependent Transport

Although membrane traffic can occur in the absence of microtubules, the rapid metabolism of many eucaryotic cells requires that vesicular organelles are actively transported. Microtubule-dependent transport is particularly robust in actively growing cells and the volume of membrane transported increases dramatically in going from static to growth conditions. Both inward and outward movement are regulated simultaneously implying coordinate activation of both motors or a transport cycle. Relatively large complexes of the microtubule motors and associated proteins are responsible for powering the movements (reviewed in Vallee and Sheetz, 1996). Of the many motors that have been described, kinesin and cytoplasmic dynein are the most abundant and have been the focus of these studies. Included in the microtubule motor complexes are motor receptors and activating factors. A membranous motor receptor, kinectin, was identified on the basis of its interaction with kinesin (Toyoshima et al., 1992). An antibody to kinectin blocks both kinesin binding to organelles and kinesin-dependent motility of those organelles (Kumar et al., 1995).

Microtubule motors and other maps

1990 ◽  
Vol 48 (3) ◽  
pp. 1-1
Author(s):  
Richard B. Vallee
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Cytoplasmic Dynein ◽  
Organelle Transport ◽  
Structural Components ◽  
Microtubule Associated Proteins ◽  
Microtubule Motors ◽  
Associated Proteins ◽  
The Subject ◽  
Intracellular Motility

Microtubules are involved in a number of forms of intracellular motility, including mitosis and bidirectional organelle transport. Purified microtubules from brain and other sources contain tubulin and a diversity of microtubule associated proteins (MAPs). Some of the high molecular weight MAPs - MAP 1A, 1B, 2A, and 2B - are long, fibrous molecules that serve as structural components of the cytamatrix. Three MAPs have recently been identified that show microtubule activated ATPase activity and produce force in association with microtubules. These proteins - kinesin, cytoplasmic dynein, and dynamin - are referred to as cytoplasmic motors. The latter two will be the subject of this talk.Cytoplasmic dynein was first identified as one of the high molecular weight brain MAPs, MAP 1C. It was determined to be structurally equivalent to ciliary and flagellar dynein, and to produce force toward the minus ends of microtubules, opposite to kinesin.

scholarly journals Dynactin is required for bidirectional organelle transport

2003 ◽  
Vol 160 (3) ◽  
pp. 297-301 ◽  
Author(s):  
Sean W. Deacon ◽  
Anna S. Serpinskaya ◽  
Patricia S. Vaughan ◽  
Monica Lopez Fanarraga ◽  
Isabelle Vernos ◽  
...  
Keyword(s):  
Cell Types ◽  
Cytoplasmic Dynein ◽  
Opposite Polarity ◽  
Model System ◽  
Organelle Transport ◽  
Transport Activity ◽  
Microtubule Motors ◽  
Microtubule Motor ◽  
Dynactin Complex ◽  
Binding Subunit

Kinesin II is a heterotrimeric plus end–directed microtubule motor responsible for the anterograde movement of organelles in various cell types. Despite substantial literature concerning the types of organelles that kinesin II transports, the question of how this motor associates with cargo organelles remains unanswered. To address this question, we have used Xenopus laevis melanophores as a model system. Through analysis of kinesin II–mediated melanosome motility, we have determined that the dynactin complex, known as an anchor for cytoplasmic dynein, also links kinesin II to organelles. Biochemical data demonstrates that the putative cargo-binding subunit of Xenopus kinesin II, Xenopus kinesin II–associated protein (XKAP), binds directly to the p150Glued subunit of dynactin. This interaction occurs through aa 530–793 of XKAP and aa 600–811 of p150Glued. These results reveal that dynactin is required for transport activity of microtubule motors of opposite polarity, cytoplasmic dynein and kinesin II, and may provide a new mechanism to coordinate their activities.

scholarly journals Microtubule-organizing center formation at telomeres induces meiotic telomere clustering

2013 ◽  
Vol 200 (4) ◽  
pp. 385-395 ◽  
Author(s):  
Masashi Yoshida ◽  
Satoshi Katsuyama ◽  
Kazuki Tateho ◽  
Hiroto Nakamura ◽  
Junpei Miyoshi ◽  
...  
Keyword(s):  
Chromosome Pairing ◽  
Light Chain ◽  
Homologous Chromosome ◽  
Cytoplasmic Dynein ◽  
Dynein Light Chain ◽  
Microtubule Organizing Center ◽  
Homologous Chromosome Pairing ◽  
Microtubule Motors ◽  
Microtubule Motor ◽  
Organizing Center

During meiosis, telomeres cluster and promote homologous chromosome pairing. Telomere clustering requires the interaction of telomeres with the nuclear membrane proteins SUN (Sad1/UNC-84) and KASH (Klarsicht/ANC-1/Syne homology). The mechanism by which telomeres gather remains elusive. In this paper, we show that telomere clustering in fission yeast depends on microtubules and the microtubule motors, cytoplasmic dynein, and kinesins. Furthermore, the γ-tubulin complex (γ-TuC) is recruited to SUN- and KASH-localized telomeres to form a novel microtubule-organizing center that we termed the “telocentrosome.” Telocentrosome formation depends on the γ-TuC regulator Mto1 and on the KASH protein Kms1, and depletion of either Mto1 or Kms1 caused severe telomere clustering defects. In addition, the dynein light chain (DLC) contributes to telocentrosome formation, and simultaneous depletion of DLC and dynein also caused severe clustering defects. Thus, the telocentrosome is essential for telomere clustering. We propose that telomere-localized SUN and KASH induce telocentrosome formation and that subsequent microtubule motor-dependent aggregation of telocentrosomes via the telocentrosome-nucleated microtubules causes telomere clustering.

scholarly journals The Interaction of Neurofilaments with the Microtubule Motor Cytoplasmic Dynein

2004 ◽  
Vol 15 (11) ◽  
pp. 5092-5100 ◽  
Author(s):  
Oliver I. Wagner ◽  
Jennifer Ascaño ◽  
Mariko Tokito ◽  
Jean-Francois Leterrier ◽  
Paul A. Janmey ◽  
...  
Keyword(s):  
Axonal Transport ◽  
Specific Interaction ◽  
Cytoplasmic Dynein ◽  
Live Cells ◽  
Slow Axonal Transport ◽  
Force Microscopy ◽  
Atomic Force ◽  
Microtubule Motors ◽  
Microtubule Motor ◽  
Physical Interactions

Neurofilaments are synthesized in the cell body of neurons and transported outward along the axon via slow axonal transport. Direct observation of neurofilaments trafficking in live cells suggests that the slow outward rate of transport is due to the net effects of anterograde and retrograde microtubule motors pulling in opposition. Previous studies have suggested that cytoplasmic dynein is required for efficient neurofilament transport. In this study, we examine the interaction of neurofilaments with cytoplasmic dynein. We used fluid tapping mode atomic force microscopy to visualize single neurofilaments, microtubules, dynein/dynactin, and physical interactions between these neuronal components. AFM images suggest that neurofilaments act as cargo for dynein, associating with the base of the motor complex. Yeast two-hybrid and affinity chromatography assays confirm this hypothesis, indicating that neurofilament subunit M binds directly to dynein IC. This interaction is blocked by monoclonal antibodies directed either to NF-M or to dynein. Together these data suggest that a specific interaction between neurofilament subunit M and cytoplasmic dynein is involved in the saltatory bidirectional motility of neurofilaments undergoing axonal transport in the neuron.

scholarly journals Dynein-mediated trafficking negatively regulates LET-23 EGFR signaling

2016 ◽  
Vol 27 (23) ◽  
pp. 3771-3779 ◽  
Author(s):  
Olga Skorobogata ◽  
Jassy Meng ◽  
Kimberley Gauthier ◽  
Christian E. Rocheleau
Keyword(s):  
Growth Factor Receptor ◽  
Cytoplasmic Dynein ◽  
Negative Regulator ◽  
In Vivo Model ◽  
Endosomal Trafficking ◽  
Egfr Signaling ◽  
Cellular Functions ◽  
Microtubule Motor ◽  
The Many

Epidermal growth factor receptor (EGFR) signaling is essential for animal development, and increased signaling underlies many human cancers. Identifying the genes and cellular processes that regulate EGFR signaling in vivo will help to elucidate how this pathway can become inappropriately activated. Caenorhabditis elegans vulva development provides an in vivo model to genetically dissect EGFR signaling. Here we identified a mutation in dhc-1, the heavy chain of the cytoplasmic dynein minus end–directed microtubule motor, in a genetic screen for regulators of EGFR signaling. Despite the many cellular functions of dynein, DHC-1 is a strong negative regulator of EGFR signaling during vulva induction. DHC-1 is required in the signal-receiving cell and genetically functions upstream or in parallel to LET-23 EGFR. LET-23 EGFR accumulates in cytoplasmic foci in dhc-1 mutants, consistent with mammalian cell studies in which dynein is shown to regulate late endosome trafficking of EGFR with the Rab7 GTPase. However, we found different distributions of LET-23 EGFR foci in rab-7 versus dhc-1 mutants, suggesting that dynein functions at an earlier step of LET-23 EGFR trafficking to the lysosome than RAB-7. Our results demonstrate an in vivo role for dynein in limiting LET-23 EGFR signaling via endosomal trafficking.

scholarly journals Competition between microtubule-associated proteins directs motor transport

2017 ◽  
Author(s):  
Brigette Y. Monroy ◽  
Danielle L. Sawyer ◽  
Bryce E. Ackermann ◽  
Melissa M. Borden ◽  
Tracy C. Tan ◽  
...  
Keyword(s):  
Molecular Motor ◽  
Cytoplasmic Dynein ◽  
Inhibitory Effect ◽  
Microtubule Associated Proteins ◽  
Motor Transport ◽  
Branch Formation ◽  
Microtubule Motor ◽  
Associated Proteins

Within cells, numerous motor and non-motor microtubule-associated proteins (MAPs) simultaneously converge on the microtubule lattice. How the binding activities of non-motor MAPs are coordinated and how they contribute to the balance and distribution of microtubule motor transport is unknown. Here, we examine the relationship between MAP7 and tau due to their antagonistic effects on neuronal branch formation and kinesin motility in vivo1–8. We find that MAP7 and tau compete for binding to microtubules, and determine a mechanism by which MAP7 displaces tau from the lattice. In striking contrast to the inhibitory effect of tau, MAP7 promotes kinesin-based transport in vivo and strongly enhances kinesin-1 binding to the microtubule in vitro, providing evidence for direct enhancement of motor motility by a MAP. In contrast, both MAP7 and tau strongly inhibit kinesin-3 and have no effect on cytoplasmic dynein, demonstrating that MAPs exhibit differential control over distinct classes of motors. Overall, these results reveal a general principle for how MAP competition dictates access to the microtubule to determine the correct distribution and balance of molecular motor activity.

scholarly journals The role of motor proteins in endosomal sorting

2011 ◽  
Vol 39 (5) ◽  
pp. 1179-1184 ◽  
Author(s):  
Sylvie D. Hunt ◽  
David J. Stephens
Keyword(s):  
Membrane Trafficking ◽  
Spatial Organization ◽  
Motor Proteins ◽  
Cytoplasmic Dynein ◽  
Endosomal Sorting ◽  
Microtubule Motors ◽  
Complex Motor ◽  
Microtubule Motor ◽  
Endosomal System ◽  
And Control

Microtubule motor proteins play key roles in the spatial organization of intracellular organelles as well as the transfer of material between them. This is well illustrated both by the vectorial transfer of biosynthetic cargo from the endoplasmic reticulum to the Golgi apparatus as well as the sorting of secretory and endocytic cargo in the endosomal system. Roles have been described for dynein and kinesin motors in each of these steps. Cytoplasmic dynein is a highly complex motor comprising multiple subunits that provide functional specialization. The family of human kinesins includes over 40 members. This complexity provides immense functional diversity, yet little is known of the specific requirements and functions of individual motors during discrete membrane trafficking steps. In the present paper, we describe some of the latest findings in this area that seek to define the mechanisms of recruitment and control of activity of microtubule motors in spatial organization and cargo trafficking through the endosomal network.

Microtubule Dynamics and Organelle Transport in Reticulomyxa

1990 ◽  
Vol 48 (3) ◽  
pp. 194-195
Author(s):  
Yih-Tai Chen ◽  
Ursula Euteneuer ◽  
Ken B. Johnson ◽  
Michael P. Koonce ◽  
Manfred Schliwa
Keyword(s):  
Plasma Membrane ◽  
Light Microscopy ◽  
Cytoplasmic Dynein ◽  
Living Cells ◽  
Microtubule Dynamics ◽  
Model Systems ◽  
Organelle Transport ◽  
Biochemical Characteristics ◽  
Dependent Transport

The application of video techniques to light microscopy and the development of motility assays in reactivated or reconstituted model systems rapidly advanced our understanding of the mechanism of organelle transport and microtubule dynamics in living cells. Two microtubule-based motors have been identified that are good candidates for motors that drive organelle transport: kinesin, a plus end-directed motor, and cytoplasmic dynein, which is minus end-directed. However, the evidence that they do in fact function as organelle motors is still indirect.We are studying microtubule-dependent transport and dynamics in the giant amoeba, Reticulomyxa. This cell extends filamentous strands backed by an extensive array of microtubules along which organelles move bidirectionally at up to 20 μm/sec (Fig. 1). Following removal of the plasma membrane with a mild detergent, organelle transport can be reactivated by the addition of ATP (1). The physiological, pharmacological and biochemical characteristics show the motor to be a cytoplasmic form of dynein (2).

Integration host factor alleviates H-NS silencing of the Salmonella enterica serovar Typhimurium master regulator of SPI1, hilA

Microbiology ◽  
2011 ◽  
Vol 157 (9) ◽  
pp. 2504-2514 ◽  
Author(s):  
Mário H. Queiroz ◽  
Cristina Madrid ◽  
Sònia Paytubi ◽  
Carlos Balsalobre ◽  
Antonio Juárez
Keyword(s):  
Stationary Phase ◽  
Salmonella Enterica ◽  
Growth Conditions ◽  
Integration Host Factor ◽  
Band Shift ◽  
Global Regulators ◽  
Serovar Typhimurium ◽  
Associated Proteins ◽  
Transcription Data

Coordination of the expression of Salmonella enterica invasion genes on Salmonella pathogenicity island 1 (SPI1) depends on a complex circuit involving several regulators that converge on expression of the hilA gene, which encodes a transcriptional activator (HilA) that modulates expression of the SPI1 virulence genes. Two of the global regulators that influence hilA expression are the nucleoid-associated proteins Hha and H-NS. They interact and form a complex that modulates gene expression. A chromosomal transcriptional fusion was constructed to assess the effects of these modulators on hilA transcription under several environmental conditions as well as at different stages of growth. The results obtained showed that these proteins play a role in silencing hilA expression at both low temperature and low osmolarity, irrespective of the growth phase. H-NS accounts for the main repressor activity. At high temperature and osmolarity, H-NS-mediated silencing completely ceases when cells enter the stationary phase, and hilA expression is induced. Mutants lacking IHF did not induce hilA in cells entering the stationary phase, and this lack of induction was dependent on the presence of H-NS. Band-shift assays and in vitro transcription data showed that for hilA induction under certain growth conditions, IHF is required to alleviate H-NS-mediated silencing.

scholarly journals Microtubule-based Endoplasmic Reticulum Motility in Xenopus laevis: Activation of Membrane-associated Kinesin during Development

1999 ◽  
Vol 10 (6) ◽  
pp. 1909-1922 ◽  
Author(s):  
Jon D. Lane ◽  
Victoria J. Allan
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Types ◽  
Cytoplasmic Dynein ◽  
Culture Cell ◽  
Tissue Culture Cell ◽  
Differential Interference Contrast Microscopy ◽  
Animal Cells ◽  
Microtubule Motor ◽  
Directed Motility ◽  
Conventional Kinesin

The endoplasmic reticulum (ER) in animal cells uses microtubule motor proteins to adopt and maintain its extended, reticular organization. Although the orientation of microtubules in many somatic cell types predicts that the ER should move toward microtubule plus ends, motor-dependent ER motility reconstituted in extracts ofXenopus laevis eggs is exclusively a minus end-directed, cytoplasmic dynein-driven process. We have used Xenopusegg, embryo, and somatic Xenopus tissue culture cell (XTC) extracts to study ER motility during embryonic development inXenopus by video-enhanced differential interference contrast microscopy. Our results demonstrate that cytoplasmic dynein is the sole motor for microtubule-based ER motility throughout the early stages of development (up to at least the fifth embryonic interphase). When egg-derived ER membranes were incubated in somatic XTC cytosol, however, ER tubules moved in both directions along microtubules. Data from directionality assays suggest that plus end-directed ER tubule extensions contribute ∼19% of the total microtubule-based ER motility under these conditions. In XTC extracts, the rate of ER tubule extensions toward microtubule plus ends is lower (∼0.4 μm/s) than minus end-directed motility (∼1.3 μm/s), and plus end-directed motility is eliminated by a function-blocking anti-conventional kinesin heavy chain antibody (SUK4). In addition, we provide evidence that the initiation of plus end-directed ER motility in somatic cytosol is likely to occur via activation of membrane-associated kinesin.

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