Induction of Human Fetal Globin Gene Expression by a Novel Erythroid Factor, NF-E4

Abstract

The stage selector protein (SSP) is a heteromeric complex involved in preferential expression of the human γ-globin genes in fetal-erythroid cells. We have previously identified the ubiquitous transcription factor CP2 as a component of this complex. Using the protein dimerization domain of CP2 in a yeast two-hybrid screen, we have cloned a novel gene, NF-E4, encoding the tissue-restricted component of the SSP. NF-E4 and CP2 coimmunoprecipitate from extract derived from a fetal-erythroid cell line, and antiserum to NF-E4 ablates binding of the SSP to the γ promoter. NF-E4 is expressed in fetal liver, cord blood, and bone marrow and in the K562 and HEL cell lines, which constitutively express the fetal globin genes. Enforced expression of NF-E4 in K562 cells and primary erythroid progenitors induces endogenous fetal globin gene expression, suggesting a possible strategy for therapeutic intervention in the hemoglobinopathies.

ACKNOWLEDGMENTS

The first two authors contributed equally to this work.

We thank Stuart Orkin, Art Nienhuis, Jerry Adams, and Glenn Begley for critical reading of the manuscript, Robert Hawley for the gift of the MSCV plasmid, Patrick Kelly and Derek Persons for the gift of the RD18 packaging cell line, and Amy McEwan and Helen Zogos for technical assistance. We also thank members of the Jane and Cunningham laboratories for helpful discussions and Art Nienhuis for continuing support.

This work was supported by the NHMRC of Australia, The Wellcome Trust (S.M.J.), the Anti-Cancer Council of Victoria (D.R.C.), NIH PO1 HL53749-03, Cancer Center Support CORE grant P30 CA 21765, the American Lebanese Syrian Associated Charities (ALSAC), and the Assisi Foundation of Memphis.