Principles of microtubule polarity in linear cells

2022 ◽  
Author(s):  
Melissa M. Rolls
Keyword(s):  
Microtubule Polarity

The Role of Microtubule Polarity in the Movement of Kinesin and Kinetochores

1986 ◽  
Vol 1986 (Supplement 5) ◽  
pp. 121-128 ◽  
Author(s):  
T. J. MITCHISON
Keyword(s):  
Microtubule Polarity

Organelle motility and metabolism in axons vs dendrites of cultured hippocampal neurons

1996 ◽  
Vol 109 (5) ◽  
pp. 971-980 ◽  
Author(s):  
C.C. Overly ◽  
H.I. Rieff ◽  
P.J. Hollenbeck
Keyword(s):  
Regional Variation ◽  
Hippocampal Neurons ◽  
Retrograde Transport ◽  
Organelle Transport ◽  
Microtubule Polarity ◽  
Large Phase ◽  
Organelle Motility ◽  
The Difference ◽  
Metabolic Properties ◽  
Cultured Hippocampal Neurons

Regional regulation of organelle transport seems likely to play an important role in establishing and maintaining distinct axonal and dendritic domains in neurons, and in managing differences in local metabolic demands. In addition, known differences in microtubule polarity and organization between axons and dendrites along with the directional selectivity of microtubule-based motor proteins suggest that patterns of organelle transport may differ in these two process types. To test this hypothesis, we compared the patterns of movement of different organelle classes in axons and different dendritic regions of cultured embryonic rat hippocampal neurons. We first examined the net direction of organelle transport in axons, proximal dendrites and distal dendrites by video-enhanced phase-contrast microscopy. We found significant regional variation in the net transport of large phase-dense vesicular organelles: they exhibited net retrograde transport in axons and distal dendrites, whereas they moved equally in both directions in proximal dendrites. No significant regional variation was found in the net transport of mitochondria or macropinosomes. Analysis of individual organelle motility revealed three additional differences in organelle transport between the two process types. First, in addition to the difference in net transport direction, the large phase-dense organelles exhibited more persistent changes in direction in proximal dendrites where microtubule polarity is mixed than in axons where microtubule polarity is uniform. Second, while the net direction of mitochondrial transport was similar in both processes, twice as many mitochondria were motile in axons than in dendrites. Third, the mean excursion length of moving mitochondria was significantly longer in axons than in dendrites. To determine whether there were regional differences in metabolic activity that might account for these motility differences, we labeled mitochondria with the vital dye, JC-1, which reveals differences in mitochondrial transmembrane potential. Staining of neurons with this dye revealed a greater proportion of highly charged, more metabolically active, mitochondria in dendrites than in axons. Together, our data reveal differences in organelle motility and metabolic properties in axons and dendrites of cultured hippocampal neurons.

scholarly journals Polarity of dynein-microtubule interactions in vitro: cross-bridging between parallel and antiparallel microtubules.

1981 ◽  
Vol 89 (1) ◽  
pp. 35-44 ◽  
Author(s):  
F D Warner ◽  
D R Mitchell
Keyword(s):  
Original Population ◽  
Microtubule Polarity ◽  
Ciliary Motion ◽  
Dynein Arms ◽  
Cross Bridges

Ciliary doublet microtubules produced by sliding disintegration in 20 muM MgATP2-reassociate in the presence of exogenous 30S dynein and 6 mM MgSO4. The doublets form overlapping arrays, held together by dynein cross-bridges. Dynein arms on both A and B subfibers serve as unambiguous markers of microtubule polarity within the arrays. Doublets reassociate via dynein cross-bridges in both parallel and antiparallel modes, although parallel interactions are favored 2:1. When 20 muM ATP is added to the arrays, the doublets undergo both vanadate-sensitive and insensitive forms of secondary disintegration to reproduce the original population of doublets. The results demonstrate that both parallel and antiparallel doublet cross-bridging is sensitive to dissociation by ATP even though normal ciliary motion depends strictly on dynein interactions between parallel microtubules.

scholarly journals Inhibition of a Mitotic Motor Compromises the Formation of Dendrite-like Processes from Neuroblastoma Cells

1997 ◽  
Vol 136 (3) ◽  
pp. 659-668 ◽  
Author(s):  
Wenqian Yu ◽  
David J. Sharp ◽  
Ryoko Kuriyama ◽  
Prabhat Mallik ◽  
Peter W. Baas
Keyword(s):  
Retinoic Acid ◽  
Cell Division ◽  
Antisense Oligonucleotides ◽  
Motor Proteins ◽  
Molecular Motor ◽  
Neuroblastoma Cells ◽  
Opposite Orientation ◽  
Microtubule Polarity ◽  
Process Formation ◽  
Spindle Midzone

Microtubules in the axon are uniformly oriented, while microtubules in the dendrite are nonuniformly oriented. We have proposed that these distinct microtubule polarity patterns may arise from a redistribution of molecular motor proteins previously used for mitosis of the developing neuroblast. To address this issue, we performed studies on neuroblastoma cells that undergo mitosis but also generate short processes during interphase. Some of these processes are similar to axons with regard to their morphology and microtubule polarity pattern, while others are similar to dendrites. Treatment with cAMP or retinoic acid inhibits cell division, with the former promoting the development of the axon-like processes and the latter promoting the development of the dendrite-like processes. During mitosis, the kinesin-related motor termed CHO1/MKLP1 is localized within the spindle midzone where it is thought to transport microtubules of opposite orientation relative to one another. During process formation, CHO1/ MKLP1 becomes concentrated within the dendrite-like processes but is excluded from the axon-like processes. The levels of CHO1/MKLP1 increase in the presence of retinoic acid but decrease in the presence of cAMP, consistent with a role for the protein in dendritic differentiation. Moreover, treatment of the cultures with antisense oligonucleotides to CHO1/MKLP1 compromises the formation of the dendrite-like processes. We speculate that a redistribution of CHO1/MKLP1 is required for the formation of dendrite-like processes, presumably by establishing their characteristic nonuniform microtubule polarity pattern.

scholarly journals Orientation and structure of the Ndc80 complex on the microtubule lattice

2008 ◽  
Vol 182 (6) ◽  
pp. 1055-1061 ◽  
Author(s):  
Elizabeth M. Wilson-Kubalek ◽  
Iain M. Cheeseman ◽  
Craig Yoshioka ◽  
Arshad Desai ◽  
Ronald A. Milligan
Keyword(s):  
Image Analysis ◽  
Binding Mode ◽  
Cryoelectron Microscopy ◽  
Globular Domain ◽  
Considerable Distance ◽  
Microtubule Polarity ◽  
Ndc80 Complex ◽  
Spindle Microtubules ◽  
Interaction Surface ◽  
Β Tubulin

The four-subunit Ndc80 complex, comprised of Ndc80/Nuf2 and Spc24/Spc25 dimers, directly connects kinetochores to spindle microtubules. The complex is anchored to the kinetochore at the Spc24/25 end, and the Ndc80/Nuf2 dimer projects outward to bind to microtubules. Here, we use cryoelectron microscopy and helical image analysis to visualize the interaction of the Ndc80/Nuf2 dimer with microtubules. Our results, when combined with crystallography data, suggest that the globular domain of the Ndc80 subunit binds strongly at the interface between tubulin dimers and weakly at the adjacent intradimer interface along the protofilament axis. Such a binding mode, in which the Ndc80 complex interacts with sequential α/β-tubulin heterodimers, may be important for stabilizing kinetochore-bound microtubules. Additionally, we define the binding of the Ndc80 complex relative to microtubule polarity, which reveals that the microtubule interaction surface is at a considerable distance from the opposite kinetochore-anchored end; this binding geometry may facilitate polymerization and depolymerization at kinetochore-attached microtubule ends.

Modeling Bidirectional Transport of New and Used Organelles in Fast Axonal Transport in Neurons

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
A. V. Kuznetsov
Keyword(s):  
Axonal Transport ◽  
Cell Body ◽  
Molecular Motors ◽  
Molecular Motor ◽  
Fast Axonal Transport ◽  
Concentration Difference ◽  
Neuron Body ◽  
Microtubule Polarity ◽  
Bidirectional Transport ◽  
The Right

This paper develops a model for simulating transport of newly synthesized material from the neuron body toward the synapse of the axon as well as transport of misfolded and aggregated proteins back to the neuron body for recycling. The model demonstrates that motor-assisted transport, much similar to diffusion, can occur due to a simple concentration difference between the cell body and the synapse; organelles heading to the synapse do not need to attach preferably to plus-end-directed molecular motors, same as organelles heading to the neuron body for recycling do not need to attach preferably to minus-end-directed molecular motors. The underlying mechanics of molecular-motor-assisted transport is such that organelles would be transported to the right place even if new and used organelles had the same probability of attachment to plus-end-directed (and minus-end-directed) motors. It is also demonstrated that the axon with organelle traps and a region with a reversed microtubule polarity would support much smaller organelle fluxes of both new and used organelles than a healthy axon. The flux of organelles is shown to decrease as the width of organelle traps increases.

APC nuclear membrane association and microtubule polarity

2008 ◽  
Vol 100 (4) ◽  
pp. 243-252 ◽  
Author(s):  
Ludovic Collin ◽  
Karni Schlessinger ◽  
Alan Hall
Keyword(s):  
Nuclear Membrane ◽  
Membrane Association ◽  
Microtubule Polarity
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