[Effects of transcription factor GATA-2 on transcriptive regulation of iASPP gene]

iASPP can prompt the cell proliferation and inhibit the apoptosis of many cells. There are putative binding sites of transcription factor GATA-2 upstream of iASPP transcription start site. GATA-2 plays an important role in the proliferation and differentiation of hematopoietic stem cells (HSC) and progenitors. This study was aimed to explore the role of GATA-2 protein in iASPP gene transcription. Firstly, the expression of iASPP and GATA-2 protein in some leukemia cell lines was detected by Western blot. Second, The expressive vector of pCMV5-GATA2 and the luciferase reporter vectors containing possible binding sites of GATA-2 were constructed and co-transfected into HEK293 and CV-1 cells. Then the luciferase activity was assayed by luminometer. Also, ChIP assays were performed to further confirm the specific binding of GATA-2 to iASPP promoter. The results showed that GATA-2 was overexpressed in most cell lines with high level of iASPP. GATA-2 exhibited a significant effect on luciferase activity of reporter gene iASPP and in a dose-dependant manner. The relative luciferase activity was up-regulated to about two-fold of the empty vector control when the transfection dose of pCMV5-GATA2 plasmid was increased to 100 ng. While the effect was more significant in CV-1 cells and showed a 6.7-fold increase. The ChIP assay demonstrated the in vivo specific binding of GATA-2 to iASPP. The binding sites of GATA2 were located between nt -361 ∼ -334 in upstream of iASPP gene transcription start site. It is concluded that transcription factor GATA-2 can bind with the cis-regulatory region of the iASPP promoter and up-regulate iASPP expression.