Antagonistic Regulation of β-Globin Gene Expression by Helix-Loop-Helix Proteins USF and TFII-I

Abstract

The human β-globin genes are expressed in a developmental stage-specific manner in erythroid cells. Gene-proximal cis-regulatory DNA elements and interacting proteins restrict the expression of the genes to the embryonic, fetal, or adult stage of erythropoiesis. In addition, the relative order of the genes with respect to the locus control region contributes to the temporal regulation of the genes. We have previously shown that transcription factors TFII-I and USF interact with the β-globin promoter in erythroid cells. Herein we demonstrate that reducing the activity of USF decreased β-globin gene expression, while diminishing TFII-I activity increased β-globin gene expression in erythroid cell lines. Furthermore, a reduction of USF activity resulted in a significant decrease in acetylated H3, RNA polymerase II, and cofactor recruitment to the locus control region and to the adult β-globin gene. The data suggest that TFII-I and USF regulate chromatin structure accessibility and recruitment of transcription complexes in the β-globin gene locus and play important roles in restricting β-globin gene expression to the adult stage of erythropoiesis.

We thank Takeesha Roland and Jian Tang for expert technical assistance and our colleagues in the laboratory and Tom Yang (UF) for stimulating discussions. We thank Rolf Renne (UF) for allowing us to use the Nucleofector. We thank Charles Vinson (NIH) for the A-USF expression construct, Robert G. Roeder for USF and TFII-I expression constructs and TFII-I antibodies, Michael Kilberg (UF) for anti-HA antibodies, Ed Seto (University of South Florida) for HDAC3 antibodies, Ananda Roy for TFII-I antibodies, and Ann Dean (NIH) for the K562 cell line.

This work was supported by alumni fellowships (UF) to V.J.C.-D. and K.F.V. and grants from the NIH to J.B. (DK58209 and DK52356).