Abstract：

Heterochromatin protein 1 beta (HP1β) is a multiple function chromosomal protein involved in a variety of cellular processes, including heterochromatin formation and gene silencing, telomere capping and silencing, and control of gene expression [1]. Recent studies indicate that HP1β also plays a role in DNA damage repair although it is inconclusive due to conflicting results.  Herein, we employed mass spectrometry to identity a comprehensive interaction network mediated by the HP1β-chromodomain (HP1β-CD) and developed an approach to systematically identify methyllysine sites in the HP1β interactome by selected reaction monitoring (SRM). The dynamic nature of methylation was studied using deuterium labeled cells under conditions to induce DNA double strand breaks (DSB). Our data indicate HP1β function as an adaptor during DSB repair through a methyllysine-mediated interaction with DNA-PKcs. Knockdown of HP1β or mutation of the methyllysine sites in DNA-PKcs caused dislocation of activated DNA-PKcs from DNA damage foci and increased the sensitivity of cells to ion radiation.

Dr. Huadong Liu简历
Huadong Liu got his Master’s Degree from Beijing Polytechnic University in 2003 and PhD from the Department of Chemistry, Tsinghua University in 2007. He is now working as research associate in Dr. Shawn Li’s lab in Department of Biochemistry, University of Western Ontario, Canada. His research interest is to understand the relationship between post-translational modifications (PTMs) and protein function. He has been involved in the identification and functional characterization of PTMs such as tyrosine phosphorylation and lysine methylation using a host of proteomic technologies such as protein and peptide arrays and mass spectrometry. His ultimate goal is to understand how dynamic protein modifications affect the associated protein-protein interaction networks and the biological processes that these networks impinge on.
Publications：
1. Liu, H., Bi-directional array rebuilds a global view of SH2-CD22 interaction, in preparation
2. Liu, H., Characterization of the HP1β-lysine methylation and its function in DSB repair, in preparation
3. Xu, C., Bian, C., Yang, W., Galka, M., Ouyang, H., Chen, C., Qiu, W., Liu, H., Jones, A., Mackenzie, F., et al. (2010). Proc Natl Acad Sci U S A 107(45),19266.
4. Liu, H., Galka, M., Iberg, A., Wang, Z., Li, L., Voss, C., Jiang, X., Lajoie, G., Huang, Z., Bedford, M., et al. (2010). J Proteome Res 9, 5827
5. Kaneko, T., Huang, H., Zhao, B., Li, L., Liu, H., Voss, C., Wu, C., Schiller, M., and Li, S. (2010). Sci Signal 3, ra34.
6. Cheng, Z., Tang, Y., Chen, Y., Kim, S., Liu, H., Li, S., Gu, W., and Zhao, Y. (2009). Mol Cell Proteomics 8, 45
7. Liu, H., Li, Y., Du, J., Hu, J., and Zhao, Y. (2006). J Mass Spectrom 41, 208-215.
8. Liu, H., Zhao, Y., and Li, Y. (2006). International Journal of Peptide Research and Therapeutics, 237