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Mars promotes dTACC dephosphorylation on mitotic spindles to ensure spindle stability

Shengjiang Tan1, Ekaterina Lyulcheva, Jon Dean

  • 1Department of Zoology, Oxford University, Oxford OX1 3PS, England, UK.

The Journal of Cell Biology
|July 16, 2008
PubMed

Insights

Mars, a microtubule-associated protein (MAP), is crucial for stabilizing mitotic spindles in early embryos. It regulates dTACC phosphorylation, ensuring accurate chromosome segregation during development.

Area of Science:

  • Cell Biology
  • Developmental Biology
  • Genetics

Background:

  • Microtubule-associated proteins (MAPs) regulate microtubule dynamics and mitotic spindle stability, critical for chromosome segregation.
  • The precise function and regulation of MAPs during embryonic development remain incompletely understood.

Purpose of the Study:

  • To investigate the role of mars, a Drosophila melanogaster hepatoma up-regulated protein family MAP, in early embryogenesis.
  • To elucidate the regulatory mechanisms involving Mars, protein phosphatase 1 (PP1), and the spindle assembly factor dTACC.

Main Methods:

  • In vivo association studies of Mars with spindle microtubules.
  • Co-immunoprecipitation assays to identify Mars-interacting proteins.
  • Analysis of dTACC phosphorylation levels in mars mutants and rescue experiments.

Main Results:

  • Mars is essential for microtubule stabilization in early Drosophila embryogenesis.
  • Mars directly binds to PP1 and interacts with minispindles and dTACC.
  • Loss of mars function leads to increased spindle phosphorylation of dTACC.
  • A nonphosphorylatable dTACC mutant rescues mars lethality.

Conclusions:

  • Mars acts as a key regulator of spindle stabilization by mediating the dephosphorylation of dTACC via PP1.
  • Spatially controlled dephosphorylation of dTACC by Mars is critical for proper spindle function during development.

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