Abstract
The dynamic and reversed expression of GATA1 and GATA2 are essential for proper erythroid differentiation. Our previous work demonstrates that LSD1, a histone H3K4 demethylase, represses GATA2 expression at late stage of erythroid differentiation. K562 and MEL cells were used and cultured in Roswell Park Memorial Institute-1640 medium (RPMI) and Dulbecco's modified Eagle's medium (DMEM), respectively. Western blot assay was used to examine the GATA1, GATA2, TAL1, HDAC1, HDAC2, CoREST and β-actin protein. The immunoprecipitation assay and GST pull-down assay were employed to detect the precipitated protein complexes and investigate the interaction between the proteins. The small interfering RNA (siRNA) and nonspecific control siRNA were synthesized to silence the target genes. Double fluorescence immunostaining was used to observe the association of LSD1 with GATA2 in K562 cells. The results indicated that knockdown of LSD1 in K562 cell causes increased H3K4 di-methylation at GATA1 locus and activates GATA1 expression, demonstrating that LSD1 represses GATA1 expression through LSD1-mediated histone demethylation. Upon induced erythroid differentiation of K562 cells, the interaction between GATA2 and LSD1 is decreased, consistent with a de-repression of GATA1 expression. Meanwhile, the interaction between TAL1 and LSD1 is increased, which forms a complex that efficiently suppresses GATA2 expression. In conclusion, these observations reveal an elegant mechanism to modulate GATA1 and GATA2 expression during erythroid differentiation. While LSD1 mainly forms complex with GATA2 to repress GATA1 expression in hematopoietic progenitor cells, it mostly forms complex with TAL1 to repress GATA2 expression in differentiated cells.