The interaction of MYC with the trithorax protein ASH2L promotes gene transcription by regulating H3K27 modification.
Bottom Line: We found that the trithorax protein ASH2L and MYC interact directly in vitro and co-localize in cells and on chromatin.MYC does not regulate this methyltransferase activity but stimulates demethylation and subsequently acetylation of H3K27.Finally WDR5, another core subunit of KMT2 complexes, also binds directly to MYC and in genome-wide analyses MYC and WDR5 are associated with transcribed promoters.
Affiliation: Institute of Biochemistry and Molecular Biology, Medical School, RWTH Aachen University, 52074 Aachen, Germany.Show MeSH
Mentions: In a previous study, we identified three proteins that interact with MYC (34). One of these proteins is ARTD10/PARP10, a mono-ADP-ribosyltransferase (57). The other two proteins were identified as ASH2L and nucleolin. ASH2L was of interest to us because it has been described as a component of KMT2 group MTase complexes (14,58,59). Moreover, we found that ASH2L possesses transforming activity together with Ha-RAS in rat embryo fibroblasts and that the ASH2L protein, but not the mRNA, is overexpressed in the majority of human tumors (38,60). In the following, we have studied the interaction of MYC with ASH2L. To verify our initial purification result, MYC was immunoprecipitated (IPed) from lysates of U2OS cells using MYC-specific mAbs. We detected ASH2L in these but not in the control immunoprecipitates (IPs) (Figure 1A) with mAbs that we generated and that detect ASH2L specifically (Supplementary Figure S1A and B). These MYC complexes also contained nucleolin (data not shown) and an interaction between ASH2L and nucleolin was also seen (Supplementary Figure S1C). Moreover, ASH2L was co-IPed from Jurkat T cells and HEK293 cells using MYC- and MAX-specific antibodies, MAX being the heterodimeric partner of MYC (Supplementary Figure 1C and D). In a reciprocal experiment, ASH2L was IPed and MYC was detected in the complex (Figure 1B). Together these findings suggest that MYC interacts with ASH2L in cell extracts. To address whether MYC and ASH2L are also in close proximity in cells, we performed PLAs (45,61). MYC- and ASH2L-containing structures were identified exclusively in cell nuclei (Figure 1C), further supporting an interaction of ASH2L with MYC.
Affiliation: Institute of Biochemistry and Molecular Biology, Medical School, RWTH Aachen University, 52074 Aachen, Germany.