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PMS2 endonuclease activity has distinct biological functions and is essential for genome maintenance

Johanna M M van Oers1, Sergio Roa, Uwe Werling

  • 1Department of Cell Biology, and Cancer Center, Albert Einstein College of Medicine, Bronx, NY 10461, USA.

Proceedings of the National Academy of Sciences of the United States of America
|July 14, 2010
PubMed

Insights

The DNA mismatch repair protein PMS2 has a novel endonuclease activity essential for genome maintenance and tumor suppression. Its deficiency increases mutation rates and cancer risk, impacting B cell diversity but not male fertility.

Area of Science:

  • Genetics
  • Molecular Biology
  • Cancer Research

Background:

  • The DNA mismatch repair (MMR) pathway is crucial for genomic stability.
  • The protein PMS2, a key MMR component, was recently discovered to possess endonuclease activity.
  • The biological significance of this endonuclease activity in mammals remained largely undetermined.

Purpose of the Study:

  • To investigate the in vivo biological functions of the PMS2 endonuclease activity.
  • To elucidate the role of PMS2 endonuclease activity in genome maintenance, cancer predisposition, and immune system processes.

Main Methods:

  • Generation of endonuclease-deficient Pms2E702K knock-in mice (Pms2EK/EK).
  • Assessment of genomic mutation rates and cancer predisposition in Pms2EK/EK mice.
  • Analysis of B cell class switch recombination and somatic hypermutation.
  • Evaluation of male fertility in Pms2EK/EK mice compared to Pms2-/- mice.

Main Results:

  • Pms2EK/EK mice exhibited significantly increased genomic mutation rates.
  • These mice showed a strong predisposition to developing cancer.
  • Class switch recombination was impaired in Pms2EK/EK B cells, while somatic hypermutation remained unaffected.
  • Unlike Pms2-/- mice, Pms2EK/EK male mice were fertile, indicating dispensability in spermatogenesis.

Conclusions:

  • The endonuclease activity of PMS2 plays distinct biological roles separate from its canonical MMR functions.
  • PMS2 endonuclease activity is essential for maintaining genome stability and suppressing tumor formation.
  • This activity is specifically required for Ig diversity through its role in class switch recombination.

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