10. DNA damage response and cancer

Question 1

Why is DNA constantly damaged?

Answer 1

By genotoxic agents (UV light, ionising radiation)

By errors in replication - error rate in DNA polymerase

Question 2

What does mismatch repair recognise?

Answer 2

Erroneous base incorporations from replication & recombination

Question 3

What genes are involved in MMR?

What complexes do they form and what’s their role?

Answer 3

MSH2, MSH6, MLH1, PMS2

MSH2-MSH6 - repairs single base mismatches & mononucleotide repeats
MSH2-MSH3 - repairs dinucleotide repeat errors
MLH1-PMS2