We are working to establish an in vitro system for the study of checkpoint activation by the DNA damage response systems operating in human cells. As a model system, we are investigating checkpoint activation mediated by the DNA mismatch repair proteins MutSalpha and MutLalpha in response to several DNA damaging agents including SN1 alkylators, fluorouracil, and cisplatin. DNA damage sensors that target specific types of DNA damage activate the ATR and ATM protein kinases. This, in turn, activates a cascade of signaling kinases including Chk1 and Chk2 that ultimately result in cell cycle arrest at the G2/M boundary. We are purifying recombinant human proteins involved in this damage response with the goal of defining the underlying molecular mechanism. We are also studying the oligomerization of a key tumor suppressor, p53. We have identified two amino acids at the C-terminus that affect formation of stable oligomers and are characterizing their effect on various functions of p53 in in vitro assays and in cells.

Project Start
Project End
Budget Start
Budget End
Support Year
3
Fiscal Year
2009
Total Cost
$655,970
Indirect Cost
City
State
Country
Zip Code
Li, Zhongdao; Pearlman, Alexander H; Hsieh, Peggy (2016) DNA mismatch repair and the DNA damage response. DNA Repair (Amst) 38:94-101
Hsieh, Peggy; Pearlman, Alexander H (2015) EGFR inhibits DNA mismatch repair. Proc Natl Acad Sci U S A 112:5556-7
Hsieh, Peggy (2012) DNA mismatch repair: Dr. Jekyll and Mr. Hyde? Mol Cell 47:665-6