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Published on: March 31, 2010

PCNA-MutSalpha-mediated binding of MutLalpha to replicative DNA with mismatched bases to induce apoptosis in human

Masumi Hidaka1, Yasumitsu Takagi, Tomoko Y Takano

  • 1Department of Molecular Biology, Biomolecular Engineering Research Institute, 6-2-3 Furuedai, Suita, Osaka 565-0874, Japan. hidaka@beri.or.jp

Nucleic Acids Research
|October 6, 2005
PubMed

Insights

DNA repair proteins MutSalpha, MutLalpha, and PCNA form a complex on damaged DNA, triggering apoptosis. This process is linked to DNA replication, highlighting PCNA's role in cell death.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • DNA Repair Mechanisms

Background:

  • Alkylating agents generate DNA damage, such as O6-methylguanines, which can lead to apoptosis.
  • Understanding the molecular players involved in DNA damage response and apoptosis induction is crucial.

Purpose of the Study:

  • To investigate the protein complex formation on DNA damaged by N-methyl-N-nitrosourea in human cells.
  • To elucidate the sequential binding events of DNA repair proteins and their role in apoptosis.

Main Methods:

  • Immunoprecipitation using chromatin extracts from treated human cells.
  • Chemical crosslinking to stabilize protein-protein interactions.
  • Time course experiments and analysis of protein complex formation in cells with genetic modifications or treated with inhibitors.

Main Results:

  • A sequential binding of MutSalpha (MSH2/MSH6) and PCNA to damaged DNA, followed by MutLalpha (MLH1/PMS2) was observed.
  • PCNA and MutSalpha form a complex independently of MLH1, but MutLalpha association requires MSH2.
  • Reduced PCNA levels or inhibition of DNA replication suppressed the formation of the PCNA-MutSalpha-MutLalpha complex and apoptosis.

Conclusions:

  • The formation of the MutSalpha-MutLalpha-PCNA complex on damaged DNA is a key event in apoptosis induction.
  • Apoptosis induction is coupled with DNA replication progression, mediated by PCNA's involvement in the DNA repair complex.

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