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Microtubule-bundling activity of the centrosomal protein, Cep169, and its binding to microtubules

Yusuke Mori1, Yuki Taniyama1, Sayori Tanaka1

  • 1Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University, 3-4-1 Ohkubo, Tokyo 169-8555, Japan.

Biochemical and Biophysical Research Communications
|October 21, 2015
PubMed

Insights

Cep169 protein stabilizes microtubules (MTs) by forming homodimers that crosslink adjacent MTs. This bundling activity, dependent on its N- and C-terminal domains, enhances MT stability and acetylation, particularly when co-expressed with CDK5RAP2.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Cytoskeleton Dynamics

Background:

  • CDK5RAP2 is a centrosomal protein regulating microtubule (MT) dynamics and γ-tubulin ring complex (γ-TuRC) recruitment.
  • Cep169, a CDK5RAP2 binding partner, localizes to MT plus-ends and centrosomes, influencing MT stability.
  • Previous studies indicated Cep169's role in MT depolymerization upon depletion, but its stabilization mechanism remained unclear.

Purpose of the Study:

  • To elucidate the mechanism by which Cep169 stabilizes microtubules.
  • To investigate the structural domains of Cep169 responsible for MT stabilization and bundling.
  • To determine the role of Cep169 homodimerization in MT organization.

Main Methods:

  • Expression of Cep169 and its mutants in U2OS cells.
  • Analysis of MT polymerization, bundling, and acetylation.
  • Co-immunoprecipitation and interaction studies to assess Cep169 dimerization and MT binding.

Main Results:

  • Overexpression of Cep169 promotes MT stabilization, leading to the formation of long MT bundles with increased acetylation.
  • Cep169 forms homodimers via its N-terminal domain and directly binds MTs through its C-terminal domain.
  • Mutants lacking either the N-terminal or C-terminal domain abrogated Cep169's MT bundling and stabilization activity.

Conclusions:

  • Cep169 functions as a homodimer to bundle and stabilize microtubules by crosslinking adjacent MTs.
  • Both the N-terminal domain (for dimerization) and C-terminal domain (for MT interaction) are crucial for Cep169's function.
  • Cep169 plays a significant role in regulating MT structure and stability, potentially in conjunction with CDK5RAP2.
Keywords:
+TIPsCDK5RAP2CentrosomeMAPsMicrotubule bundle

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