Delocalization of EAF1 in murine MLL-ELL leukemic cell lines.

Murine hematopoietic cells were examined with antibodies to ELL, EAF1, or MLL as indicated in the upper left of each image. To confirm the normal expression patterns of ELL and EAF1 in murine hematopoietic cells, confocal microscopy was used to examine normal bone marrow progenitor cells (A) and the BaF/3 cell line (B). ELL and EAF1 colocalized in a nuclear speckled pattern similar to that observed in human cells. To determine the distribution of EAF1 in cells that stably expressed the MLL-ELL fusion protein, we examined a cell line derived from hematopoietic progenitors that were immortalized in vitro by MLL-ELL (C) and a cell line derived from MLL-ELL leukemic mice (D). Confocal microscopy in both of these cell lines showed expression of ELL in a punctate pattern. In contrast, EAF1 exhibited a fainter, diffuse nucleoplasmic pattern, with no speckles detected. These cell lines were also incubated with antibodies to MLL and ELL, which revealed a punctate pattern for both proteins (E,F). A subset of the MLL and ELL speckles colocalized, suggesting that both antibodies were detecting the MLL-ELL fusion protein.