Related Experiment Video

Updated: Jul 8, 2026

Reconstitution of Basic Mitotic Spindles in Spherical Emulsion Droplets
10:52

Reconstitution of Basic Mitotic Spindles in Spherical Emulsion Droplets

Published on: August 13, 2016

The microtubule-based motor Kar3 and plus end-binding protein Bim1 provide structural support for the anaphase

Melissa K Gardner1, Julian Haase, Karthikeyan Mythreye

  • 1Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA.

The Journal of Cell Biology
|January 9, 2008
PubMed

Insights

Cell survival after dicentric chromosome activation in yeast requires specific microtubule-binding proteins. Their absence leads to anaphase spindle collapse, highlighting their roles in maintaining spindle stability.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Genetics

Background:

  • Budding yeast mitotic spindles consist of kinetochore microtubules (kMTs) and interpolar MTs (ipMTs).
  • Anaphase involves kMT shortening and ipMT elongation, with overlapping MTs crucial for spindle integrity.
  • Dicentric chromosomes pose a challenge to spindle stability by creating tension and potential breakage.

Purpose of the Study:

  • To investigate the requirements for anaphase spindle stability in the presence of a dicentric chromosome.
  • To identify microtubule-binding proteins essential for surviving dicentric chromosome-induced stress.

Main Methods:

  • Introduction of a conditionally functional dicentric chromosome into budding yeast.
  • Analysis of cell survival and anaphase spindle dynamics under dicentric chromosome conditions.
  • Assessment of the roles of specific microtubule-binding proteins (Kar3p, Bim1p, Ase1p).

Main Results:

  • Cell survival after dicentric chromosome activation is dependent on Kar3p, Bim1p, and Ase1p.
  • Absence of these proteins leads to anaphase spindle collapse and buckling.
  • Bim1p promotes ipMT polymerization for overlap zone stability; Kar3p cross-links spindle MTs.

Conclusions:

  • Kar3p, Bim1p, and Ase1p are critical for maintaining anaphase spindle stability against dicentric chromosome challenges.
  • Bim1p and Kar3p have distinct but complementary roles in ensuring spindle integrity during anaphase.
  • This study elucidates key molecular mechanisms underlying mitotic spindle resilience.

More Related Videos

Directly Measuring Forces Within Reconstituted Active Microtubule Bundles07:47

Directly Measuring Forces Within Reconstituted Active Microtubule Bundles

Published on: May 10, 2022

Self-Assembly of Microtubule Tactoids08:49

Self-Assembly of Microtubule Tactoids

Published on: June 23, 2022

Related Concept Videos

The Mitotic Spindle02:27

The Mitotic Spindle

The mitotic spindle—or spindle apparatus—is a eukaryotic, cytoskeletal structure made up of long protein fibers called microtubules. Formed during cell division, the spindle separates sister chromatids and moves them to opposite ends of a parental cell, where the now individual chromosomes are distributed to two daughter cell nuclei.
The bipolar configuration of the mitotic spindle facilitates chromosomal segregation, preparing the cell for division. One mechanism that ensures bipolar mitotic...
The Mitotic Spindle02:27

The Mitotic Spindle

The mitotic spindle—or spindle apparatus—is a eukaryotic, cytoskeletal structure made up of long protein fibers called microtubules. Formed during cell division, the spindle separates sister chromatids and moves them to opposite ends of a parental cell, where the now individual chromosomes are distributed to two daughter cell nuclei.
The bipolar configuration of the mitotic spindle facilitates chromosomal segregation, preparing the cell for division. One mechanism that ensures bipolar mitotic...
Spindle Assembly02:50

Spindle Assembly

Spindle assembly occurs through three, often coexisting, pathways – the centrosome-mediated pathway, the chromatin-mediated pathway, and the microtubule-mediated pathway – collectively contributing to form a robust spindle apparatus.
In most cells, centrosomes are the primary microtubule nucleation centers. In the centrosome-mediated pathway, the G2-prophase transition triggers centrosome maturation and increased microtubule nucleation. Progressive nucleation results in a microtubule array...
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...
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...
Forces Acting on Chromosomes02:11

Forces Acting on Chromosomes

During mitosis, chromosome movements occur through the interplay of multiple piconewton level forces. In prometaphase, these forces help in chromosome assembly or congression at the equatorial plane, eventually leading to their alignment at the metaphase plate. The forces acting on the chromosomes are space and time-dependent; therefore, they vary with the position of the chromosomes as the cell progresses through mitosis. 
Microtubules and motor proteins exert two types of forces on...