Microtubule catastrophe and rescue - PubMed (original) (raw)

Review

Microtubule catastrophe and rescue

Melissa K Gardner et al. Curr Opin Cell Biol. 2013 Feb.

Abstract

Microtubules are long cylindrical polymers composed of tubulin subunits. In cells, microtubules play an essential role in architecture and motility. For example, microtubules give shape to cells, serve as intracellular transport tracks, and act as key elements in important cellular structures such as axonemes and mitotic spindles. To accomplish these varied functions, networks of microtubules in cells are very dynamic, continuously remodeling through stochastic length fluctuations at the ends of individual microtubules. The dynamic behavior at the end of an individual microtubule is termed 'dynamic instability'. This behavior manifests itself by periods of persistent microtubule growth interrupted by occasional switching to rapid shrinkage (called microtubule 'catastrophe'), and then by switching back from shrinkage to growth (called microtubule 'rescue'). In this review, we summarize recent findings which provide new insights into the mechanisms of microtubule catastrophe and rescue, and discuss the impact of these findings in regards to the role of microtubule dynamics inside of cells.

Copyright © 2012 Elsevier Ltd. All rights reserved.

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Figures

Figure 1

Figure 1. Cellular effects of microtubule aging regulation

(A) In a single step process, the microtubule length distribution is exponential (left), while microtubule aging leads to a non-exponential length distribution of microtubules (right), allowing for a more effective search-and-capture mechanism. (B) Lack of fine-tuning of microtubule lengths leads to improper metaphase chromosome alignment during mitosis (left, red arrows denoting the magnitude of kinetochore oscillations), while tight spatial regulation of microtubule lengths by the effects of a Kinesin-8 molecular motor on microtubule growth rate and microtubule aging allows for proper alignment (right, green arrows denoting the magnitude of kinetochore oscillations). (C) Due to the aging process, short (young) microtubules continue growth at the completion of mitosis (left, green arrows denote growing, while red crosses denote shrinking microtubules). By turning catastrophe into a single-step process, MCAK leads to indiscriminatory microtubule disassembly (right).

Figure 2

Figure 2. Rescue events are not strongly correlated to tubulin concentration

In data reproduced from Walker et al, the net on-rate of tubulin subunits during microtubule growth increases monotonically as a function of tubulin concentration. However, rescue frequency remains relatively constant regardless of the tubulin concentration.

Figure 3

Figure 3. Possible rescue mechanisms

(A) In one mechanism, GTP-tubulin “islands” remain embedded within the microtubule lattice (blue=GDP-tubulin, red = GTP-tubulin), and provide a nucleation point for rescue events. (B) In another mechanism, tension at the depolymerizing microtubule end could promote rescue by straightening the curled GDP-tubulin subunits during microtubule depolymerization.

Box 1

Box 1

Microtubule Catastrophe: Single vs. Multi-Step Process

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