Negative cross-talk between hematopoietic regulators: GATA proteins repress PU.1

Negative cross-talk between hematopoietic regulators: GATA proteins repress PU.1

^*Hematology/Oncology Division, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215; ^†Liem Sioe Liong Molecular Biology Laboratory, Department of Surgery and Genetics, Stanford University School of Medicine, Stanford, CA 94305; and ^‡The New England Baptist Bone and Joint Institute, Beth Israel Deaconess Medical Center, and Department of Pathology, Harvard Medical School, Boston, MA 02115

Edited by David E. Housman, Massachusetts Institute of Technology, Cambridge, MA, and approved May 25, 1999 (received for review November 24, 1998)

Abstract

The process through which multipotential hematopoietic cells commit to distinct lineages involves the induction of specific transcription factors. PU.1 (also known as Spi-1) and GATA-1 are transcription factors essential for the development of myeloid and erythroid lineages, respectively. Overexpression of PU.1 and GATA-1 can block differentiation in lineages in which they normally are down-regulated, indicating that not only positive but negative regulation of these factors plays a role in normal hematopoietic lineage development. Here we demonstrate that a region of the PU.1 Ets domain (the winged helix–turn–helix wing) interacts with the conserved carboxyl-terminal zinc finger of GATA-1 and GATA-2 and that GATA proteins inhibit PU.1 transactivation of critical myeloid target genes. We demonstrate further that GATA inhibits binding of PU.1 to c-Jun, a critical coactivator of PU.1 transactivation of myeloid promoters. Finally, PU.1 protein can inhibit both GATA-1 and GATA-2 transactivation function. Our results suggest that interactions between PU.1 and GATA proteins play a critical role in the decision of stem cells to commit to erythroid vs. myeloid lineages.

Footnotes

↵ § To whom reprint requests should be addressed at: Harvard Institutes of Medicine, Room 954, 77 Avenue Louis Pasteur, Boston, MA 02115. e-mail: dtenen{at}caregroup.harvard.edu.
This paper was submitted directly (Track II) to the Proceedings Office.
ABBREVIATIONS:

CBP,

CREB-binding protein;

C/EBPα,

CCAAT enhancer-binding protein;

GST,

glutathione S-transferase;

M-CSF,

macrophage-granulocyte stimulating factor;

PEST,

region rich in proline (P), glutamate (E), serine (S), and threonine (T);

EMSA,

electrophoretic mobility-shift assay;

TK,

thymidine kinase