A heterologous MLL-EAF2 fusion immortalizes hematopoietic cells.

The open reading frame of EAF2 was fused to the amino-terminus of MLL in the MSCV vector. High titer retroviruses were generated in Bosc23 cells and used to infect primary murine hematopoietic progenitor cells. For comparison, MLL-ELL, MLL-EAF1, and MSCV vector alone retroviral constructs were also examined. (A) The number of colonies generated in tertiary passage in methylcellulose cultures. (B) Expression of the MLL fusion proteins by Western blot in transiently transfected Bosc23 cells using antibodies to ELL, EAF1, and EAF2. (C) Expression of these constructs by RT-PCR in the transduced hematopoietic cells. Amplification from reverse transcribed cDNA is indicated by a plus symbol (+). To exclude contamination with integrated retroviral genomic DNA, a no reverse transcriptase control is indicated by a minus symbol (−).