JMJD1C contributes to MLL-rearranged leukemia maintenance by affecting MYB, MYC, and HOXA9-MEIS1 gene expression programs. (A) MLL-AF9 cells were cotransduced with pMLS-YFP carrying shScr or shJmjd1c (868) and empty vector or pMSCV-GFP vector expressing mouse Myb or Myc complementary DNA. Normalized ratios of GFP⁺YFP⁺ cell percentages between shJmjd1c and shScr samples are plotted over a 10-day time course starting from day 2 after transduction. Average of 3 independent experiments. Error bars indicate standard deviation. (B) Relative mRNA levels of the indicated genes in MLL-AF9 cells from one of the experiments in (A). (C) Relative mRNA levels of the indicated genes in SEM cells over a 48-hour JMJD1C inducible KD time course with 12-hour intervals. (D) Model for MLL-rearranged implementation of transformation programs. JMJD1C, MYC, MYB, HOXA9, and MEIS1 are bound and their transcription is maintained by MLL-AF4 and MLL-AF9. In the presence of sufficient levels of JMJD1C, cells remain transformed. However, upon reduction of JMJD1C levels, transformation and stem cell programs are hindered through deregulation of MYC, MYB, and HOXA9-MEIS1 target gene expression, leading to cells displaying an apoptotic phenotype.