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Degradation of human RAP80 is cell cycle regulated by Cdc20 and Cdh1 ubiquitin ligases

Hyun Jung Cho1, Eun Hee Lee, Seung Hun Han

  • 1Department of Biological Sciences, Sungkyunkwan University, 300 Cheoncheon-dong, Suwon, Republic of Korea.

Molecular Cancer Research : MCR
|March 20, 2012
PubMed

Insights

Receptor-associated protein 80 (RAP80) levels change during the cell cycle, peaking in G2. Its degradation by APC/C complexes is crucial for proper cell division and mitotic progression.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Receptor-associated protein 80 (RAP80) is a key component of the BRCA1-A complex, essential for DNA damage response.
  • RAP80 depletion impairs the G2-M phase checkpoint control, highlighting its role in cell cycle regulation.

Purpose of the Study:

  • To investigate the cell cycle-dependent regulation of RAP80 protein levels.
  • To elucidate the mechanisms controlling RAP80 stability and degradation.
  • To determine the role of RAP80 regulation in mitotic progression.

Main Methods:

  • Cell cycle analysis to monitor RAP80 protein levels.
  • Ubiquitination assays to assess protein modification.
  • Anaphase-promoting complex (APC/C) knockdown using small interfering RNAs (siRNAs).
  • Mutagenesis of RAP80 destruction box (D-box) to study protein stability.

Main Results:

  • RAP80 protein levels exhibit cell cycle fluctuations, peaking in G2 and declining during mitosis and G1.
  • RAP80 undergoes polyubiquitination and degradation mediated by APC/C(Cdc20) and APC/C(Cdh1).
  • Knockdown of Cdc20 or Cdh1 inhibits RAP80 degradation, while D-box mutations affect its stability and ubiquitination.
  • Overexpression of a RAP80 D-box deletion mutant disrupts mitotic progression.

Conclusions:

  • APC/C(Cdc20) and APC/C(Cdh1) complexes regulate RAP80 stability from mitosis to G1.
  • RAP80 degradation is critical for timely mitotic progression.
  • This study reveals a novel function of RAP80 in regulating cell division through controlled degradation.

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