Push-me-pull-you: how microtubules organize the cell interior

Abstract

Dynamic organization of the cell interior, which is crucial for cell function, largely depends on the microtubule cytoskeleton. Microtubules move and position organelles by pushing, pulling, or sliding. Pushing forces can be generated by microtubule polymerization, whereas pulling typically involves microtubule depolymerization or molecular motors, or both. Sliding between a microtubule and another microtubule, an organelle, or the cell cortex is also powered by molecular motors. Although numerous examples of microtubule-based pushing and pulling in living cells have been observed, it is not clear why diVerent cell types and processes employ diVerent mechanisms. This review introduces a classiWcation of microtubule-based positioning strategies and discusses the eYcacy of pushing and pulling. The positioning mechanisms based on microtubule pushing are eYcient for movements over small distances, and for centering of organelles in symmetric geometries. Mechanisms based on pulling, on the other hand, are typically more elaborate, but are necessary when the distances to be covered by the organelles are large, and when the geometry is asymmetric and complex. Thus, taking into account cell geometry and the length scale of the movements helps to identify general principles of the intracellular layout based on microtubule forces.

Intrinsic microtubule GTP-cap dynamics in semi-confined systems: kinetochore–microtubule interface

“…If the extent of hydrolysis is greater than the extent of association, i.e., m h > m a (13) then, CNLC is greater than the bulk critical concentration. If the extent of hydrolysis is less than the extent of association,…”

“…Owing to the great extent of dynamic instability, microtubules play a critical role in crucial cellular events such as dislocation of intracellular components, signaling during cellular division and movement [9][10][11][12][13].…”

Cytoskeletal dynamics in fission yeast: A review of models for polarization and division

“…The solution evolution found for fission yeast may differ due to cell geometry, chromosome count, and the closed nature of mitosis, among other factors. Efficient organelle positioning by microtubules depends on cell shape (Tolić-Nørrelykke, 2008). Pushing forces predominate in short and symmetric cell interiors such as the fission-yeast nucleus.…”

Dynamic instability — A common denominator in prokaryotic and eukaryotic DNA segregation and cell division

“…Additionally, this mini-review should support the notion that any dynamically unstable filament could serve as the molecular machine driving DNA segregation, but these machines possess auxiliary features to adapt to temporal and spatial disparities in either system. Key words: Dynamic instability, Microtubules, ParM filaments, R1 plasmid, Mitosis, Mitotic spindle, Brownian ratchet, Cytoskeleton evolution, Catastrophe/recovery Microtubule-mediated sister chromatid segregation during anaphase is a fundamental process in the nuclear division of most eukaryotic cells [1,2]. In a related prokaryotic process, proper segregation of duplicated R1 antibiotic resistance plasmid is achieved using the ParM/ParR/parC actin-like motility system encoded in the par operon of R1 [3,4].…”

“…Microtubules (MTs) have well-documented roles in eukaryotic cells ranging from organelle positioning and intracellular organization to vesicular trafficking and mitotic chromatid segregation [1,2]. To properly align and separate sister chromatids, the cell must correctly orient the mitotic spindle both spatially and temporally [1].…”