The tumor suppressor p53 is mutated in about half of all human malignancies. In most of the remaining cancers, the function of p53 is compromised due to alterations in signaling pathways that regulate p53 activity. Despite recent advances, the overall 5-year survival rate for cancer patients remains very low and there is an urgent need for the development of more efficient anti-cancer therapies. p53 is an attractive therapeutic target and understanding the molecular mechanisms of its regulation is essential for the design of new treatment strategies. Our preliminary data reveal that p53 activity can be modulated by protein effectors 53BP (p53-binding protein 1) and L3MBT (lethal 3 malignant brain tumor) that recognize methylated lysine marks on p53. The molecular mechanisms underlying these novel interactions of p53 are unknown and will be elucidated in the proposed studies. Detailed knowledge of these mechanisms is of fundamental importance for understanding the physiological and tumorigenic activities of p53. We hypothesize that binding of the MBT domain of L3MBT to monomethylated p53 (p53K382me1) represses p53 transactivation, whereas binding of the 53BP Tudor domain to dimethylated p53 (p53K382me2) facilitates p53 accumulation at DNA damage sites and promotes DNA repair. Furthermore, we propose that nearby posttranslational modifications (PTMs) of p53 alter the binding properties of these effectors and fine-tune p53 functions. We seek to define the structural basis and functional consequences of the interactions of 53BP and L3MBT with methylated p53 (p53me).
The specific aims of this project are: (1) to determine the molecular basis of p53 recognition by 53BP and (2) to elucidate the molecular mechanism of p53 targeting by L3MBT. The three-dimensional structures of 53BP Tudor and L3MBT MBT in complex with singly and doubly modified p53 peptides will be determined by X-ray crystallography or NMR. The specificities, binding affinities and the crosstalk between PTMs of p53 will be examined. The binding site residues will be mutated and the mutant 53BP and L3MBT proteins will be tested in vitro by fluorescence spectroscopy, isothermal titration calorimetry and NMR and in vivo by immunoprecipitation (IP), chromatin IP, PCR and DNA damage assays. In-depth biochemical, structural and functional characterization of the p53me effectors will provide a comprehensive understanding of the mechanistic principles underlying physiological and oncogenic activities of p53 and may facilitate the development of novel anti-cancer therapies.
The major tumor suppressor p53 is mutated in about half of all human cancers. The proposed studies will greatly enhance our knowledge of how the biological functions of p53 are regulated in normal cells and during tumorigenesis and may help to identify new targets for therapeutic interventions.
| Zhang, Yi; Mun, Su Ran; Linares, Juan F et al. (2018) ZZ-dependent regulation of p62/SQSTM1 in autophagy. Nat Commun 9:4373 |
| Klein, Brianna J; Krajewski, Krzysztof; Restrepo, Susana et al. (2018) Recognition of cancer mutations in histone H3K36 by epigenetic writers and readers. Epigenetics 13:683-692 |
| Andrews, Forest H; Singh, Alok R; Joshi, Shweta et al. (2017) Dual-activity PI3K-BRD4 inhibitor for the orthogonal inhibition of MYC to block tumor growth and metastasis. Proc Natl Acad Sci U S A 114:E1072-E1080 |
| Tencer, Adam H; Gatchalian, Jovylyn; Klein, Brianna J et al. (2017) A Unique pH-Dependent Recognition of Methylated Histone H3K4 by PPS and DIDO. Structure 25:1530-1539.e3 |
| Klein, Brianna J; Simithy, Johayra; Wang, Xiaolu et al. (2017) Recognition of Histone H3K14 Acylation by MORF. Structure 25:650-654.e2 |
| Simithy, Johayra; Sidoli, Simone; Yuan, Zuo-Fei et al. (2017) Characterization of histone acylations links chromatin modifications with metabolism. Nat Commun 8:1141 |
| Andrews, Forest H; Strahl, Brian D; Kutateladze, Tatiana G (2016) Insights into newly discovered marks and readers of epigenetic information. Nat Chem Biol 12:662-8 |
| Klein, Brianna J; Wang, Xiaoyan; Cui, Gaofeng et al. (2016) PHF20 Readers Link Methylation of Histone H3K4 and p53 with H4K16 Acetylation. Cell Rep 17:1158-1170 |
| Andrews, Forest H; Shanle, Erin K; Strahl, Brian D et al. (2016) The essential role of acetyllysine binding by the YEATS domain in transcriptional regulation. Transcription 7:14-20 |
| Zhang, Xi; Peng, Danni; Xi, Yuanxin et al. (2016) G9a-mediated methylation of ER? links the PHF20/MOF histone acetyltransferase complex to hormonal gene expression. Nat Commun 7:10810 |
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