Erythroid-specific 5-aminolevulinate synthase (ALAS2) catalyzes the rate-limiting step in heme biosynthesis of erythroid cells. Here, we show that treatment of erythroid K562 cells with HDAC inhibitors sodium butyrate or Trichostatin A gave rise to a significant increase in ALAS2 gene transcripts, with a concurrent increase in acetylation level of historic H4 at the ALAS2 gene promoter. Histone acetyltransferase p300 bound with ALAS2 promoter and overexpression of p300 increased both the promoter reporter expression and endogenous mRNA level of ALAS2. Additionally, two functional Sp1 sites located in ALAS2 promoter were identified. Both of the GATA-I sites and all the Sp1 sites at the ALAS2 promoter contributed to the transcription synergistic action with p300. These data implicated a close relationship between the acetylation modification of histone at the ALAS2 promoter and the regulation of this gene. Meanwhile, this work identified that ALAS2 is a novel target gene for p300/CBP action as historic acetyltransferases. (c) 2006 Published by Elsevier Inc.