Contributions of Mutant p53 Oligomerization and C-Terminal Domains to Tumorigenic Gain-of-Function Activities
G.K. Annor1,2, G. Xiao2, S. Maimos2, DG. Conde2, and J. Bargonetti1,2,3
1The Graduate Center- City University of New York (CUNY)
2The Department of Biological Sciences Hunter College
3Weill Cornell Medical College, New York City
The TP53 gene is often mutated in cancer, with missense mutations found in the central DNA binding domain, and less often in the oligomerization domain (OD) and C-terminal domain (CTD). The OD and CTD has been found to be critical for the tumor suppressor functionality of wild-type p53 (wtp53). Thus, mutations that destabilize tetramer formation as well as substitution of key lysine residues within the CTD downregulate the ability of wtp53 to transactivate critical tumor suppressing target genes. We previously found that mutant p53 (mtp53) R273H associates with replicating DNA and promotes the chromatin association of replication-associated proteins mini-chromosome maintenance 2 (MCM2), and poly ADP-ribose polymerase 1(PARP1). We also used the CRISPR/Cas9 gene editing system to generate two C-terminal region mutants, one with deletion within the CTD (R273HΔ381-388), and the other an OD-CTD deletion mutant (R273HΔ347-393). We reported slowed proliferation of the R273HΔ347-393 cells compared to the parentals. Herein, we tested whether deletions within the OD and/or CTD played a role in chromatin binding oncogenic gain-of-function (GOF) activities, as well as tumor formation in vivo. We observed a significant decrease in R273HΔ381-388 and R273HΔ347-393 mtp53 chromatin association via chromatin fractionation, as well as observation via proximity ligation assay of decreased interactions with PARP1 with MCM2. In vivo mouse xenograft of the corresponding cell lines in NSG mice showed that the absence of the OD-CTD, or depletion of mtp53R273H, decreased GOF R273H mediated tumor formation, with a significant decrease in the levels of circulating tumor cells assessed via flow cytometry. Our findings suggest that the OD-CTD of mtp53 is important for key oncogenic GOF activities that help tumorigenesis.
Email questions and comments about this abstract to gannor@genectr.hunter.cuny.edu.
