The Mutant p53 C-Terminal Domain Assists in DNA Interactions and Cell Cycle Promotion
Lundine1,2*, V. Ellison2, J. Bargonetti1,2,3
1CUNY Graduate Center, Biology Department, 365 5th Ave. NY, NY, 10016
2Hunter College, Biology Department, 695 Park Ave. NY, NY, 10065
3Weill-Cornell Medical College, Department of Cell and Developmental Biology, 1300 York Ave., NY, NY, 10065
Triple-negative breast cancer (TNBC) is the most aggressive form of breast cancer and has the worst prognosis of any breast cancer sub-type. Because TNBC lacks estrogen, progesterone, and HER2 receptors, typical hormone deprivation treatments are ineffective. More than 80% of TNBC patients harbor mutated TP53, an indicator of further decreased prognosis. Some mutant p53 (mtp53) proteins exhibit gain-of function (GOF) oncogenic characteristics.
Our group previously found that mtp53 R273H interacts with newly synthesized DNA, and that mtp53 R273H increases chromatin-bound replication proteins such as MCM2-7, PCNA, and PARP1. Mutant p53 retains an intact C-terminal domain (CTD). In wild-type p53 the CTD is known to be important non-specific DNA binding. We hypothesize that the CTD of mtp53 facilitates DNA interactions at sites of DNA replication or repair and that this interaction facilitates at least some GOF oncogenic properties. To test this hypothesis, we have transiently transfected human cells to compare wild-type p53, and R273H mtp53 full–length and CTD-truncated variants. We have also used CRISPR/Cas9 to generate endogenous CTD truncations of mtp53 R273H in the breast cancer cell line MDA-MB-468. Preliminary data suggest that, for both exogenous and endogenous expression systems, mtp53 R273H and wild-type p53 with intact CTD tethers to chromatin better than CTD-truncated p53 proteins. Additionally, the CTD-truncated clone MDA-MB-468/delta380-387 demonstrates slowed cell cycle progression. Future work will focus on functional protein-protein and protein-DNA interactions mediated by CTD-mutated p53 proteins and compare how these interactions correlate with wild-type p53 interactions
Email questions and comments about this abstract to devonlundine@gmail.com.
