Poster Presentation 40th Annual Lorne Genome Conference 2019

Shining light on the MYST lysine acetyltransferase TIP60 (KAT5) (#274)

Johannes Wichmann 1 2 , Catherine Pitt 1 2 , Samantha Eccles 2 , Alexandra Garnham 1 2 , Rose May 2 , Elizabeth Allan 2 3 , Stephen Wilcox 2 , Marco Herold 1 2 , Gordon Smyth 2 4 , Brendon Monahan 1 2 3 , Tim Thomas 1 2 , Anne Voss 1 2
  1. Department of Medical Biology, University of Melbourne, Melbourne, Victoria, Australia
  2. Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
  3. Cancer Therapeutics CRC, Melbourne, Victoria, Australia
  4. Departments of Mathematics and Statistics, University of Melbourne, Melbourne, Victoria, Australia

Chromatin regulation is an essential mechanism maintaining cell homeostasis and driving differentiation. TIP60 is the founding member of the MYST family of histone lysine acetyltransferases. Although, essential in many human cancer cell lines (1), TIP60 has been described as oncogenic (2, 3) and as a tumour suppressor (4, 5). We utilised inducible Cre- and CRISPR-knockout to investigate TIP60’s biological role in murine and human cells and to shed light on TIP60’s contradicting roles.

Deletion of the TIP60 gene caused complete cell growth arrest in mouse embryonic fibroblasts (MEFs) and in human cells (HEK293, U2OS). Remarkably, the cell growth arrest was entirely independent of the cell cycle regulatory proteins INK4A, ARF and p53, suggesting that TIP60 would be a potent anti-cancer drug target. Tip60–/– cells arrest mainly in G2/M phase, with a 10-fold increase in endoreplicating cells. Comprehensive western blot analysis revealed that TIP60 is responsible for over 85% of pan-H2AZ acetylation. H2AZ acetylation is important for transcriptionally active genes. Its genome occupancy strongly correlates with promotors of active genes (6) and decreased +1-nucleosome barrier for transcription (7, 8). RNA-seq analysis of Tip60 null MEF identified a large number of genes that are dependent on TIP60 to achieve normal expression levels and will provide deeper insight into how TIP60 modulates gene activity through H2AZ acetylation.

This study may help resolve the conflicting reports on the biological role of TIP60 and is essential to gauge TIP60's potential as a therapeutic target.

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  2. Bararia D, Trivedi AK, Zada AA, Greif PA, Mulaw MA, Christopeit M, et al. Proteomic identification of the MYST domain histone acetyltransferase TIP60 (HTATIP) as a co-activator of the myeloid transcription factor C/EBPalpha. Leukemia. 2008;22(4):800-7.
  3. Halkidou K, Gnanapragasam VJ, Mehta PB, Logan IR, Brady ME, Cook S, et al. Expression of Tip60, an androgen receptor coactivator, and its role in prostate cancer development. Oncogene. 2003;22:2466.
  4. Sakuraba K, Yasuda T, Sakata M, Kitamura Y-H, Shirahata A, Goto T, et al. Down-regulation of Tip60 Gene as a Potential Marker for the Malignancy of Colorectal Cancer. Anticancer Research. 2009;29(10):3953-5.
  5. Bassi C, Li YT, Khu K, Mateo F, Baniasadi PS, Elia A, et al. The acetyltransferase Tip60 contributes to mammary tumorigenesis by modulating DNA repair. Cell Death and Differentiation. 2016;23(7):1198-208.
  6. Valdes-Mora F, Song JZ, Statham AL, Strbenac D, Robinson MD, Nair SS, et al. Acetylation of H2A.Z is a key epigenetic modification associated with gene deregulation and epigenetic remodeling in cancer. Genome Research. 2012;22(2):307-21.
  7. Weber CM, Ramachandran S, Henikoff S. Nucleosomes are context-specific, H2A.Z-modulated barriers to RNA polymerase. Molecular Cell. 2014;53(5):819-30.
  8. Subramanian V, Fields PA, Boyer LA. H2A.Z: a molecular rheostat for transcriptional control. F1000prime Reports. 2015;7:01-.