Yeats4 recruits the Dot1l–RNA Pol II complex onto the Lmo4 promoter through recognizing H3K27Ac. (A) Pull-downs were performed in BM cells from Yeats4Flag knockin mice using anti-Flag or IgG. Eluted fractions were resolved by SDS-PAGE, followed by silver staining and mass spectrometry. (B) Flag-Yeats4 precipitated Dot1l in BM cell lysates. IP, immunoprecipitation. (C) Yeats4 and Dot1l were visualized in α4β7+ CLPs from Yeats4fl/fl mice by immunofluorescence staining. Red, Yeats4; green, Dot1l. Nuclei were counterstained by DAPI. Scale bar, 5 µm. (D) Dot1l enrichment on Lmo4 promoter was analyzed via ChIP-qPCR analysis. (E) Dot1l enrichment on Lmo4 promoter was analyzed in α4β7+ progenitors (Lin−CD127+c-KitintSca-1intα4β7+) from Yeats4fl/fl and Yeats4fl/flVav-Cre mice. (F) α4β7+ CLPs cells from Yeats4fl/fl and Yeats4fl/flVav-Cre mice were in situ hybridized with probes against the Lmo4 promoter, followed by staining with antibodies against Yeats4 and Dot1l. Arrowheads indicate Lmo4 promoters colocalized with Dot1l. Scale bar, 5 µm. (G) Enrichment of H3K79me3 on the Lmo4 promoter was tested using ChIP-qPCR analysis. (H) Enrichment of H3K79me3 on the Lmo4 promoter in WT, Yeats4-deficient, or Dot1l-deficient α4β7+ progenitor (Lin−CD127+c-KitintSca-1intα4β7+) cells was examined. (I) Enrichment of RNA Pol II Ser2P on the Lmo4 promoter in WT, Yeats4-deficient or Dot1l-deficient α4β7+ progenitor (Lin−CD127+c-KitintSca-1intα4β7+) cells was analyzed. (J) BM cells from Yeats4fl/fl and Yeats4fl/flVav-Cre mice were lysed and treated with 1% formaldehyde for cross-linking. Then, anti-Dot1l antibody was incubated with treated lysates for ChIP assays, followed by size fractionation with sucrose gradient ultracentrifugation. Eluate gradients were examined by Western blotting and PCR assays. (K)
Dot1l−/− or control α4β7+ progenitors (Lin−CD127+c-KitintSca-1intα4β7+) were subjected to nuclear run-on assay, followed by RT-PCR analysis for Lmo4 transcription. (L) Dot1l-overexpressing or control α4β7+ progenitors (Lin−CD127+c-KitintSca-1intα4β7+) were subjected to nuclear run-on assay, followed by RT-PCR analysis for Lmo4 transcription. (M and N) Relative mRNA (M) and protein (N) levels of Lmo4 in Yeats4-deficient, Dot1l-deficient, or control α4β7+ progenitors (Lin−CD127+c-KitintSca-1intα4β7+) were analyzed. ***, P < 0.001 by two-tailed unpaired Student’s t test. All data are representative of at least three independent experiments and are expressed as mean ± SD.