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Apoptosis and mutation in the murine small intestine: loss of MIh1- and Pms2-dependent apoptosis leads to increased mutation in vivo

Sansom, Owen J., Bishop, Stefan Mark, Court, Helen, Dudley, Sandra, Liskay, R. Michael and Clarke, Alan Richard 2003. Apoptosis and mutation in the murine small intestine: loss of MIh1- and Pms2-dependent apoptosis leads to increased mutation in vivo. DNA Repair 2 (9) , pp. 1029-1039. 10.1016/S1568-7864(03)00111-3

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Abstract

The mismatch repair (MMR) protein Msh2 has been shown to function in the apoptotic response to alkylating agents in vivo. Here, we extend these studies to the MutL homologues (MLH) Mlh1 and Pms2 by analysing the apoptotic response within the small intestine of gene targeted strains. We demonstrate significant differences between Msh2, Mlh1 and Pms2 mutations in influencing apoptotic signalling following 50 mg/kg N-methyl-nitrosourea (NMNU), with no obvious reliance upon either Mlh1 or Pms2. However, following exposure to 100 mg/kg temozolomide or lower levels of NMNU (10 mg/kg) both Mlh1- and Pms2-dependent apoptosis was observed, indicating that the apoptotic response at these levels of DNA damage is dependent on the MutL homologues. Given our ability to observe a MutLα dependence of the apoptotic response, we tested whether perturbations of this response directly translate into increases in mutation frequency in vivo. We show that treatment with temozolomide or 10 mg/kg NMNU significantly increases mutation in both the Mlh1 and Pms2 mutant mice. At higher levels of NMNU, where the apoptotic response is independent of Mlh1 and Pms2, no gene dependent increase in mutation frequency was observed. These results argue that the MutSα and MutLα are not equally important in their ability to signal apoptosis. However, when MMR does mediate apoptosis, perturbation of this response leads to long-term persistence of mutant cells in vivo.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Biosciences
Subjects: Q Science > Q Science (General)
Uncontrolled Keywords: Mismatch repair; apoptosis; methylation; p53.
Publisher: Elsevier
ISSN: 1568-7864
Last Modified: 18 Jan 2018 21:07
URI: http://orca.cf.ac.uk/id/eprint/61365

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