Involvement of Sp1/Sp3 in the activation of the GATA-1 erythroid promoter in K562 cells

• 来源期刊: 细胞研究（英文版）
• 年，卷（期）: 2008,（2）
• 页码范围: 302-310
• 页数: 9页
• 语种: 英文

摘要

GATA-1 is a hematopoietic transcription factor that is essential for the terminal maturation of proerythroblasts, megakaryocytic cells and mast cells. The erythroid-specific promoter of the human GATA-1 gene directs the high expression of a reporter gene in K562 cells. Multiple putative transcription factor binding sites were identified in the promoter from the -860 to the -1 base pair (bp). For a better understanding of the transcriptional control of human GATA-1 gene expression, we tested the transcriptional activity of a series of deletions from the 5' end of the 860-bp promoter. A region between -221 and -128 bp retains most of the transcriptional activity of the full-length promoter. Deletion of the CGCCC box at -195 bp reduced reporter gene activity to 60.4%. Further deletion of the CACCC box at -173 bp nearly abolished reporter gene expression, indicating that the CACCC box is more critical. In vitro experiments of electrophoretic mobility shifts and in vivo studies using chromatin immuno-precipitation (ChIP) assays show that the Spl/Sp3 proteins bind the CACCC site in the nuclei of K562 cells. Coincidently, hyperacetylation of histones in the GATA-1 erythroid promoter was also shown by ChIP assay. Co-transfection of Spl expression plasmids and plasmids with a wild-type promoter showed enhanced reporter gene activity in a dose-dependent manner. The combined data demonstrate that Spl/Sp3, but not EKLF, is involved in the activation of the GATA-1 erythroid promoter, and that histones H3 and H4 are highly acetylated in this promoter region for an actively transcribed GATA-1 gene in K562 cells in which EKLF is barely detectable.