A novel mechanism of microtubule length-dependent force to pull centrosomes toward the cell center

Abstract

t he centrosome is a major microtubule-organizing center in animal cells, and its intracellular positioning is critical for defining intracellular architecture. the centrosome positions itself at the cell center. centrosome centration depends on the microtubule cytoskeleton. to accomplish robust centration regardless of the cell size or cell shape, it has been assumed that the force mediated by the microtubules depends on microtubule length. however, a concrete mechanism to generate forces to pull the centrosome in a microtubule lengthdependent manner has been elusive. recently, we successfully demonstrated that centrosome-directed movement of intracellular organelles along microtubules drives centrosome centration in the Caenorhabditis elegans early embryo. based on this observation, we proposed the centrosome-organelle mutual pulling model in which the reaction forces of organelle transport generated along microtubules act as a driving force that pulls the centrosomes toward the cell center. this is the first experiment-based model that accounts for the microtubule length-dependent pulling force generated in the cytoplasm contributing to centrosome centration. intriguingly, this model is consistent with a recent estimation that the pulling force is proportional to the cubic length of microtubules. The Emergence of Order in Cell ArchitectureThe cell can be compared to a city. A population of macromolecules lives their lives inside the cell, and they utilize the a novel mechanism of microtubule length-dependent force to pull centrosomes toward the cell center

Mitosis-Coupled, Microtubule-Dependent Clustering of Endosomal Vesicles around Centrosomes

“…1C and Video S3); this is consistent with a notion that centrosome centration is a fundamental requirement for symmetric division in animal cells (Kimura and Kimura, 2011). Open questions remain regarding how the ERC selectively clusters during mitosis and how membrane traffic is turned on and off at this compartment.…”

Centrosome Centering and Decentering by Microtubule Network Rearrangement

“…Centering capacities are generally considered to result from minus end-directed motors such as dyneins (Kimura and Kimura, 2011b). Here, by using numerical simulations, we compared the contributions result in MT network rearrangement and induce centrosome repositioning.…”

End-on microtubule-dynein interactions and pulling-based positioning of microtubule organizing centers

“…The in vitro reconstitution of MTOC positioning in microfabricated chambers has allowed us to reveal a simple reliable mechanism for pulling-based centering that is different from mechanisms that have been proposed before. [36][37][38] In cells, it remains to be confirmed how dominant this mechanism is in different cases. However, the slipping of MT ends along the cortex has been observed in living cells 37,49,50 (see, Fig.…”

“…5 In many systems, these pulling forces arise from dynein at the cortex, 3,10,12,35 although there are also cases where dynein seems distributed along the length of the MTs throughout the cytoplasm. 5,6,[36][37][38] Focusing here on the situation where pulling forces are only generated at the cortex, one can ask how pulling forces affect positioning processes. It has been argued that the abundant presence of pulling force generators at the cortex might lead to a net de-centering force.…”