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. 2005 Sep 30;102(41):14765–14770. doi: 10.1073/pnas.0503630102

Fig. 4.

Fig. 4.

MLL binds to RNA pol II and affects histone modifications and transcription elongation. (A) Interaction of MLL1-N and -C (indicated on the right) with either GST alone or RNA pol II C-terminal tail GST fusion (GST-CTD, indicated at the top). Consistent with previous experiments (30), an interaction of MLL2 and menin with the GST-CTD also was seen. In, input. (B) Immunoprecipitations performed with the Mll1-C Ab coprecipitates menin as well as the phospho-Ser-5 form of RNA pol II. Immunoprecipitations were performed in MLL-AF9 nuclear extracts. Control IPs with rabbit IgG using the same extracts also are shown. (C and D) ChIP using Abs specific for either Ser-2 (C) or Ser-5 (D) phosphorylated RNA pol II at the Hoxa9 TATA box, first exon and homeodomain. Taqman primer/probe sets used are shown in H. ChIP shows that Ser-2 is increased in the coding region (exon, HD) relative to the promoter (TATA), whereas Ser-5 is instead increased at the promoter (TATA) in Mll+/+ (blue) and F-MLL#16 (yellow) cells. Conversely, in Mll-/- cells (pink), Ser-2 and -5 are concentrated in small peaks at the promoter, suggesting a defect in transcription elongation. (E-H) ChIP for various histone modifications shows high levels of each mark at the promoter and in the coding regions of the Hoxa9 locus in Mll+/+ cells (blue). Each mark is drastically reduced in Mll-/- cells (pink) and is partially restored by MLL reexpression (yellow). Distances across the Hoxa9 locus (in kb) are shown across the bottom of each image. Positions of Taqman primer/probe sets are shown at the bottom of G and H. (E) Histone H3 dimethyl Lys-4 ChIP. (F) Histone H3 trimethyl Lys-4 ChIP. (G) Histone H3 acetyl Lys-9 ChIP. (H) Histone H3 dimethyl Lys-79 ChIP.