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A novel, evolutionarily conserved protein phosphatase complex involved in cisplatin sensitivity

Anne-Claude Gingras1, Michael Caballero, Marcel Zarske

  • 1Institute for Systems Biology, Seattle, Washington 98103, USA. agingras@systemsbiology.org

Molecular & Cellular Proteomics : MCP
|August 9, 2005
PubMed

Insights

Researchers identified a new protein complex, protein phosphatase 4-containing complex (PP4cs), crucial for DNA damage repair. Its components, including novel PP4R3, are essential for resisting cisplatin, an anticancer drug.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Biochemistry

Background:

  • The DNA damage response is critical for maintaining genomic stability.
  • Protein phosphatase 4 (PP4) is involved in DNA repair pathways.
  • Understanding the composition and function of PP4 complexes is essential.

Purpose of the Study:

  • To characterize a novel protein phosphatase 4 (PP4)-containing complex (PP4cs).
  • To investigate the role of PP4cs in the eukaryotic DNA damage response.
  • To identify novel components of the PP4 complex and their function.

Main Methods:

  • Tandem affinity purification tagging and mass spectrometry were used to identify PP4cs components.
  • Gene deletion studies in Saccharomyces cerevisiae were performed to assess sensitivity to cisplatin.
  • Complementation experiments using human PP4R3 in yeast and analysis of Drosophila melanogaster mutants were conducted.

Main Results:

  • A novel PP4-containing complex (PP4cs) was identified, comprising PP4C, PP4R2, and a new subunit, PP4R3.
  • Deletion of PP4cs orthologs in S. cerevisiae resulted in hypersensitivity to cisplatin.
  • Human PP4R3 complemented the yeast psy2 deletion, and Drosophila PP4R3 mutants showed cisplatin hypersensitivity, indicating a conserved role.
  • PP4R3 may target PP4cs to DNA damage repair machinery via interaction with Rad53 (CHK2).

Conclusions:

  • PP4cs is an evolutionarily conserved complex vital for the DNA damage response.
  • The novel subunit PP4R3 plays a critical role in conferring resistance to DNA-damaging agents like cisplatin.
  • PP4cs, potentially through PP4R3 and its interaction with Rad53, is a key player in DNA repair pathways.

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