Related Experiment Video

Updated: Jun 30, 2026

Preparation of Segmented Microtubules to Study Motions Driven by the Disassembling Microtubule Ends
12:20

Preparation of Segmented Microtubules to Study Motions Driven by the Disassembling Microtubule Ends

Published on: March 15, 2014

MCAK-independent functions of ch-Tog/XMAP215 in microtubule plus-end dynamics

Alexis R Barr1, Fanni Gergely

  • 1Cancer Research UK Cambridge Research Institute, Li Ka Shing Centre, Robinson Way, Cambridge, United Kingdom.

Molecular and Cellular Biology
|September 24, 2008
PubMed

Insights

Microtubule polymerase ch-Tog is crucial for spindle bipolarity in human cells, protecting kinetochore microtubules and independently driving centrosomal microtubule assembly. Its role is more complex than a simple antagonism with kinesin MCAK.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Genetics

Background:

  • The formation of a bipolar mitotic spindle is vital for maintaining genetic integrity during cell division.
  • In human cells, XMAP215/ch-Tog (microtubule polymerase) and XKCM1/MCAK (microtubule-depolymerizing kinesin) have antagonistic roles in spindle bipolarity.
  • The precise interplay governing microtubule dynamics in vivo remains unclear.

Purpose of the Study:

  • To investigate the in vivo roles of ch-Tog and MCAK in mammalian cell spindle assembly.
  • To elucidate the distinct functions of ch-Tog in microtubule dynamics and spindle formation.

Main Methods:

  • Real-time analysis of spindle assembly in human cells.
  • Depletion of ch-Tog and co-depletion of MCAK with ch-Tog.
  • Microscopy to assess microtubule dynamics, centrosomal microtubule length, and kinetochore fiber organization.

Main Results:

  • ch-Tog is essential for generating and maintaining long centrosomal microtubules post-nuclear envelope breakdown.
  • Absence of ch-Tog leads to impaired microtubule assembly, reduced microtubule dynamics, and shorter kinetochore fibers.
  • Co-depletion of MCAK partially rescued kinetochore fiber length and interkinetochore separation but did not restore centrosomal microtubule assembly or dynamics.

Conclusions:

  • ch-Tog has two independent roles: protecting kinetochore microtubules from MCAK and promoting centrosomal microtubule assembly.
  • The simple antagonistic model of ch-Tog and MCAK determining microtubule stability is insufficient for human cells.
  • ch-Tog plays a critical, MCAK-independent role in initiating microtubule assembly at centrosomes.

More Related Videos

Using plusTipTracker Software to Measure Microtubule Dynamics in Xenopus laevis Growth Cones07:32

Using plusTipTracker Software to Measure Microtubule Dynamics in Xenopus laevis Growth Cones

Published on: September 7, 2014

Simultaneous Visualization of the Dynamics of Crosslinked and Single Microtubules In Vitro by TIRF Microscopy07:20

Simultaneous Visualization of the Dynamics of Crosslinked and Single Microtubules In Vitro by TIRF Microscopy

Published on: February 18, 2022

Related Concept Videos

Microtubule Associated Proteins (MAPs)01:42

Microtubule Associated Proteins (MAPs)

Microtubule function and architecture are regulated by an array of specialized proteins called microtubule-associated proteins or MAPs. These proteins are widespread across different organisms and have conserved protein motifs, like the multi-TOG domain for tubulin binding found in the CLASP family of MAPs. Some MAPs are lineage-specific based on their conserved domains. Their functions depend upon the cytoskeletal architecture and cell type they are located within. In-plant cells, a specific...
Anaphase A and B01:39

Anaphase A and B

Microtubules form through the end-to-end polymerization of tubulin heterodimers. Kinetochore microtubules originate from the spindle poles, and their plus-ends connect with the kinetochores on sister-chromatids. Ndc80 protein complexes, present on the kinetochore, form low-affinity links with the plus end of these kinetochore microtubules.
Plus-end depolymerization releases tubulin heterodimers from the terminal region of the microtubule. As tubulin subunits are lost, the Ndc80 complexes detach...
Microtubule Instability02:17

Microtubule Instability

Microtubules are hollow cylindrical filaments having a diameter of approximately 25 nm and a length that varies from 200 nm to 25 μm. GTP-bound tubulin subunits form αβ-heterodimers for microtubule assembly. These core building blocks interact longitudinally, polymerizing into protofilaments. The protofilaments then interact with one another through lateral bonding forces to form stable cylindrical microtubules. These cylindrical filaments are dynamic as they undergo repeated assembly and...
Microtubule Instability02:17

Microtubule Instability

Microtubules are hollow cylindrical filaments having a diameter of approximately 25 nm and a length that varies from 200 nm to 25 μm. GTP-bound tubulin subunits form αβ-heterodimers for microtubule assembly. These core building blocks interact longitudinally, polymerizing into protofilaments. The protofilaments then interact with one another through lateral bonding forces to form stable cylindrical microtubules. These cylindrical filaments are dynamic as they undergo repeated assembly and...
Assembly of Complex Microtubule Structures01:32

Assembly of Complex Microtubule Structures

Complex microtubule structures are present in resting cells and in dividing cells. In resting cells, they are responsible for maintaining the cellular architecture, tracks for intracellular transport, positioning of organelles, assembly of cilia and flagella. They mediate the bipolar spindle assembly for chromosomal segregation and positioning of the cell division plate in dividing cells. The formation of microtubule complex structures depends on the cell type, cell stage, and cell function.
Microtubules01:18

Microtubules

Microtubules are the thickest cytoskeletal filaments with a diameter of 25 nm. In prokaryotic organisms, microtubules are commonly found in locomotory appendages like cilia and flagella. In eukaryotic cells, microtubules form specialized extensions for moving fluid over the surface, like those found in cells lining the intestine.
Microtubules have two structurally similar globular protein subunits: α and β tubulins. In the cytosol, the α and β tubulins form a heterodimer. These αβ-heterodimers...