DNA mismatch repair: Biological functions and molecular mechanisms

DNA mismatch repair (MMR) is an important genome caretaker system. It ensures genomic stability by correcting mismatches generated during DNA replication and recombination, suppressing homeologous recombination, and triggering apoptosis of cells with severe DNA damage. Protein components required for these reactions are highly conserved through evolution, and MutS-like and MutL-like proteins in mammalian cells are key players responsible for the initiation steps of both the strand-specific mismatch correction and the MMR-dependent apoptotic signaling. The inactivation of the genes encoding these activities leads to genome-wide instability, particularly in simple repetitive sequences, and the predisposition to certain types of cancer, including hereditary non-polyposis colorectal cancer.