| DNA damage response and the centrosome cycle are two of the most critical cellular processes affecting genome stability in animal cells. DNA damage response pathways play important roles in maintaining genome stability, while deficiency of genes in these pathways may lead to tumorigenesis. Many studies have focused on both DNA damage response and the centrosome. Many DNA damage response related proteins have been found localized to the centrosome. The molecular mechanism behind the centrosome cycle in non-stressed cells has been largely elucidated; yet the crosstalk between DNA damage response proteins and the centrosome remains poorly understood. Based on an immunofluorescent screening using over 100 antibodies against 44 DNA damage response factors to determine their centrosomal localization, we propose that a large number of the DNA damage response and DNA repair related proteins localize to the centrosome. The DNA damage response proteins BRCA1 and FANCJ both had established roles in DNA damage response pathways. Recently, FANCM was also found to play important roles in multiple DNA damage response pathways. Thus, here we take FANCJ, BRCA1 and FANCM as examples to further investigate how DNA damage response proteins regulate the centrosome. Our overall hypothesis is that DNA damage response proteins regulate the centrosome. In this dissertation, we propose that BRCA1 and FANCJ coordinately regulate DNA damage induced centrosome amplification through activating PLK1, while FANCM regulates centrosome biogenesis likely through its DNA damage response functions. The data from this project showed that upon DNA damage, FANCJ recruits or retains BRCA1 to or at the centrosome. Together, FANCJ and BRCA1 subsequently recruit PLK1 to the centrosome and activate it at the centrosome to facilitate DNA damage induced centrosome amplification. In addition, we show that FANCM inhibits centrosome amplification likely through its DNA damage response functions. This project not only establishes an intimate interconnection between DNA damage response and the centrosome, but may also shed new light on developing novel therapeutic strategies of treatment of human cancers. |
