LSD1-Mediated Epigenetic Modification Is Important for TAL1 Function

TAL1/SCL is critical for normal and abnormal hematopoiesis by regulating hematopoietic stem/progenitor cell growth and differentiation. However, it is still unclear how its transcriptional activities are controlled during hematopoiesis. Here, we undertook the biochemical isolation of TAL1-associated protein complexes in erythroleukemia cells and showed that TAL1 interacts with histone demethylase LSD1 complexes containing LSD1, CoREST, HDAC1 and HDAC2. Interestingly, although TAL1 specifically colocalizes with LSD1 at the target gene promoter p4.2 in undifferentiated MEL cells, the recruitment of LSD1 is decreased at the p4.2 promoter upon induced MEL differentiation indicating that LSD1 may differentially regulate TAL1 target genes during differentiation. The siRNA-mediated knockdown of LSD1 in MEL and ES cells resulted in the derepression of p4.2 by increasing dimeH3K4 at their promoter region, respectively. Finally, we demonstrated that TAL1-associated LSD1 complexes, H3K4 demethylase, and histone deacetylase activities are coordinately regulated during erythroid cell differentiation. Thus, the data suggest that LSD1 mediated epigenetic modification may affect hematopoiesis and leukemogenesis through its association with the lineage-specific transcription factor TAL1.