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EDD and DNA Damage Response
Pei-Hsuan Yang
Mentor: Phang-Lang Chen
EDD (E3 isolated by differential display or hHyd) is a HECT-domain E3 ubiquitin ligase
that, in previous studies, appears to be amplified and over expressed in several cancers,
and mutations of this gene have been linked to breast cancer. Based on the unpublished
research from my lab, it is observed that EDD is a component of the BRCA2 (breast
cancer susceptibility genes) -RAD51 (eukaryotic orthologue of bacterial RecA) complex.
Since both of these proteins are vital for homologous recombination, DNA repair, and the
maintenance of genomic stability in several ways, I proposed that EDD might play a
crucial part in modulating this complex during DNA damage repair. My hypothesis was
tested through using cell clones that contained two distinct constructs: expression EDD
shRNA and TetR. By doing this, EDD expression within the cells could be regulated.
Several U2-OS cell clones with such inducible knockdown properties were obtained. One
of these clones, USE23, has been selected for further characterization. I performed a time
course experiment to determine the kinetics of the depletion of the endogenous EDD
protein, and found the endogenous EDD protein was nearly completely depleted at Day 4
by Western blot analysis. With this information, the effects of EDD depletion on the
DNA damage repair pathway can be tested. I found that EDD depletion leads to
deregulation of several proteins, including Rad51 and E2F1, in response to DNA
damages. My preliminary results are consistent with the potential involvement of EDD in
DNA damage repair pathway.