A nuclear-derived proteinaceous matrix embeds the microtubule spindle apparatus during mitosis

Changfu Yao, Uttama Rath, Helder Maiato, David Sharp, Jack Girton, Kristen M. Johansen, Jørgen Johansen

Research output: Contribution to journalArticlepeer-review

24 Scopus citations

Abstract

The concept of a spindle matrix has long been proposed. Whether such a structure exists, however, and what its molecular and structural composition are have remained controversial. In this study, using a live-imaging approach in Drosophila syncytial embryos, we demonstrate that nuclear proteins reorganize during mitosis to form a highly dynamic, viscous spindle matrix that embeds the microtubule spindle apparatus, stretching from pole to pole. We show that this "internal" matrix is a distinct structure from the microtubule spindle and from a lamin B-containing spindle envelope. By injection of 2000-kDa dextran, we show that the disassembling nuclear envelope does not present a diffusion barrier. Furthermore, when microtubules are depolymerized with colchicine just before metaphase the spindle matrix contracts and coalesces around the chromosomes, suggesting that microtubules act as "struts" stretching the spindle matrix. In addition, we demonstrate that the spindle matrix protein Megator requires its coiled-coil amino-terminal domain for spindle matrix localization, suggesting that specific interactions between spindle matrix molecules are necessary for them to form a complex confined to the spindle region. The demonstration of an embedding spindle matrix lays the groundwork for a more complete understanding of microtubule dynamics and of the viscoelastic properties of the spindle during cell division.

Original languageEnglish (US)
Pages (from-to)3532-3541
Number of pages10
JournalMolecular biology of the cell
Volume23
Issue number18
DOIs
StatePublished - Sep 15 2012

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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