Systematic RNAi studies on the role of Sp/KLF factors in globin gene expression and erythroid differentiation.
Sp/KLF family of factors regulates gene expression by binding to the CACCC/GC/GT boxes in the DNA through their highly conserved three zinc finger domains. To investigate the role of this family of factors in erythroid differentiation and globin gene expression, we first measured the expression levels of selected Sp/KLF factors in primary cells of fetal and adult stages of erythroid development. This quantitative analysis revealed that their expression levels vary significantly in cells of either stages of the erythroid development. Significant difference in their expression levels was observed between fetal and adult erythroid cells for some Sp/KLF factors. Functional studies using RNA interference revealed that the silencing of Sp1 and KLF8 resulted in elevated level of gamma globin expression in K562 cells. In addition, K562 cells become visibly red after Sp1 knockdown. Benzidine staining revealed significant hemoglobinization of these cells, indicating erythroid differentiation. Moreover, the expression of PU.1, ETS1 and Notch1 is significantly down-regulated in the cells that underwent erythroid differentiation following Sp1 knockdown. Overexpression of PU.1 or ETS1 efficiently blocked the erythroid differentiation caused by Sp1 knockdown in K562 cells. The expression of c-Kit, however, was significantly up-regulated. These data indicate that Sp1 may play an important role in erythroid differentiation.
Hu
Jie Hong
JH
Division of Medical Genetics, Department of Medicine, University of Washington, Seattle, 1705 NE Pacific Street, Seattle, WA 98195, USA.
Navas
Patrick
P
Cao
Hua
H
Stamatoyannopoulos
George
G
Song
Chao-Zhong
CZ
D002454:Cell Differentiation; D041905:Erythroid Cells / Q000378:metabolism*; D005786:Gene Expression Regulation; D005914:Globins / Q000378:metabolism*; D006412:Hematopoietic Stem Cells / Q000378:metabolism* / Q000502:physiology; D006801:Humans; D020014:K562 Cells; D051741:Kruppel-Like Transcription Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D034622:RNA Interference; D051703:Sp Transcription Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D016329:Sp1 Transcription Factor / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014162:Transfection
D051741:Kruppel-Like Transcription Factors; D051703:Sp Transcription Factors; D016329:Sp1 Transcription Factor; D005914:Globins