Global characterization of proteome and lysine methylome features in EZH2 wild-type and mutant lymphoma cell lines.

Lysine methylation is a widespread protein post-translational modification showing essentialities in versatile cellular process. EZH2, a methyltransferase specifically trimethylates the lysine 27 of histone H3 and its aberrance in several cancers promotes the development of its inhibitors against hematological tumors. In this study, we presented a deep exploration of lysine mono-, di- and trimethylomes in EZH2 wild-type and Y641 mutant lymphoma cell lines. Our results showed that several substrates were modified in different methylation levels. Moreover, these methylated lysine residues could also undergo other types of PTMs. Combined with the differences proved in protein expression, lysine acetylation, lysine ubiquitylation and protein N-termianl acetylation level, our study underlined the substrate specificity of lysine methylation and its crosstalk with other types of PTMs. Totally, our study raised new insights into the global cellular methylation features in hematological cell lines, which provided further inspects into the distribution and function of lysine methylation. SIGNIFICANCE: Our study showed the global landscape of mono-, di- and trimethylomes in the EZH2-aberrant DLBCL cell lines, revealing the molecular characteristics of lysine methylation. Combined with the protein abundance and potential crosstalk among different types of PTMs, our study raised new insights into the global cellular methylation features in hematological tumors and provided further inspects into the distribution and function of lysine methylation.