BRCA1 Regulation of Fanconi Anemia Proteins in DNA Damage Repair

摘要

BRCA1 is strongly associated with the breast cancer. BRCA1 associates with numerous proteins that repair DNA damage. Fanconi Anemia (FA) is a rare autosomal recessive disorder. It has been shown that BRCA1 regulates one of FA proteins, called FANCD2, by a process called ubiquitination. However, exactly how the FA proteins and BRCA1 interact to regulate DNA damage repair obscure. In this project, we hypothesize that BRCA1 ubiquitination of FANCD2 is affected by association with the FANCA protein complex and by association with DNA damage when embedded in chromatin. Specific aims are that (1) does BRCA1 monoubiquitinate FANCD2 in vivo using purified ubiquitination factors; (2) Do embedding FA proteins in chromatin affect their function as ubiquitination substrates; (3) Is the ubiquitination of FA proteins by BRCA1 affected by binding to damaged DNA. During the first year of grant, we purified the FANCD2, FANCA and BRCA1/BARD1 from baculovirus-infected insect cells and we identified that BRCA1 could ubiquitinated FAND2, dependent on the E2 enzymes. Also, we found direct DNA binding activity of the FANCD2 protein. Now we are trying to know the function of FANCD2 and modified FANCD2 (ubiquitinated FANCD2) on DNA or chromatin. Finally, we are trying to understand the relationship between BRCA1 and FANCD2 in the DNA damage repair pathway by keeping this project.