Acetylation of EKLF Is Essential for Epigenetic Modification and Transcriptional Activation of the β-Globin Locus

Abstract

Posttranslational modifications of transcription factors provide alternate protein interaction platforms that lead to varied downstream effects. We have investigated how the acetylation of EKLF plays a role in its ability to alter the β-like globin locus chromatin structure and activate transcription of the adult β-globin gene. By establishing an EKLF-null erythroid line whose closed β-locus chromatin structure and silent β-globin gene status can be rescued by retroviral infection of EKLF, we demonstrate the importance of EKLF acetylation at lysine 288 in the recruitment of CBP to the locus, modification of histone H3, occupancy by EKLF, opening of the chromatin structure, and transcription of adult β-globin. We also find that EKLF helps to coordinate this process by the specific association of its zinc finger domain with the histone H3 amino terminus. Although EKLF interacts equally well with H3.1 and H3.3, we find that only H3.3 is enriched at the adult β-globin promoter. These data emphasize the critical nature of lysine acetylation in transcription factor activity and enable us to propose a model of how modified EKLF integrates coactivators, chromatin remodelers, and nucleosomal components to alter epigenetic chromatin structure and stimulate transcription.

ACKNOWLEDGMENTS

Wenjun Zhang and Felix Lohmann were involved in the initial phase of this study. We thank members of the Bieker lab for their ongoing support and discussion, and especially Felix Lohmann for his help with the ChIP assays and Saghi Ghaffari and John Crispino for help with the retroviral infections. We thank K. Wilson, Y. Nakatani, and N. Mermod for plasmid constructs, F. Morle for the shEKLF MEL cell lines, and Lee Wall and his lab for help in establishing the 18SCF cell line.

This work was supported by NIH PHS grant R01 DK46865 to J.J.B. The Quantitative PCR Shared Research Facility is supported by Mount Sinai School of Medicine.