Skip to main content
. 2021 Nov 28;22(23):12864. doi: 10.3390/ijms222312864

Figure 1.

Figure 1

Development of repeat base abnormalities and role of mismatch repair in maintaining genomic fidelity. In the left side of the figure, an example of CAG repeat (microsatellite) gains and losses during DNA replication is shown. In the right side of the figure, the role of the mismatch repair complex in preventing replication errors is described. In normal cells, the DNA mismatch repair (MMR) machinery guarantees genomic fidelity by recognizing (via MSH2/MSH6 complex) and repairing (via MLH1/PMS2/1 complex) genetic mismatches generated during DNA replication. When normal G/C base pairs are mutated into A/C base pairs during DNA replication, the repair system recognizes the error (through MSH2/MSH6) and mutated A is then removed and replaced by correct C base via MLH1 and PMS1/2 machinery. Conversely, in MSI tumor cells, the presence of a deficient MMR (dMMR) system results in the failure to repair DNA mismatches in microsatellites, resulting in the accumulation of mutations in different genomic codons. So far, MLH1, MSH2, MSH6, and PMS2/1 have been found to be the main components of the MMR machinery. Modified from figure by Puliga E et al. [24].