Context-dependent regulation of GATA-1 by friend of GATA-1

doi:10.1073/pnas.0306315101

Context-dependent regulation of GATA-1 by friend of GATA-1

^*University of Pennsylvania School of Medicine, Philadelphia, PA 19104; and ^†Division of Hematology, Children's Hospital of Philadelphia, Philadelphia, PA 19104

Edited by Mark T. Groudine, Fred Hutchinson Cancer Research Center, Seattle, WA, and approved November 6, 2003 (received for review October 1, 2003)

Abstract

The transcription factor GATA-1 and its cofactor, friend of GATA-1 (FOG-1), are essential for normal erythroid development. FOG-1 physically interacts with GATA-1 to augment or inhibit its activity. The mechanisms by which FOG-1 regulates GATA-1 function are unknown. By using an assay that is based on the phenotypic rescue of a GATA-1-null erythroid cell line, we found that a conditional form of GATA-1 (GATA-1-ER) strongly induced histone acetylation at the β-major globin promoter in vivo, consistent with previous results. In contrast, GATA-1 bearing a point mutation that impairs FOG-1 binding [GATA-1(V205M)-ER] failed to induce high levels of histone acetylation at this site. However, at DNase I-hypersensitive site (HS)3 of the β-globin locus control region, GATA-1-induced histone acetylation was FOG-1-independent. Because the V205M mutation does not disrupt GATA-1 binding to DNA templates in vitro, we were surprised to find that in vivo GATA-1(V205M)-ER fails to bind the β-globin promoter. However, at HS3, DNA binding by GATA-1 was FOG-1-independent, thus correlating histone acetylation with GATA-1 occupancy. Examination of additional GATA-1-dependent regulatory elements showed that the interaction with FOG-1 is required for GATA-1 occupancy at select sites, such as HS2, but is dispensable at others, including the FOG-1-independent GATA-1 target gene EKLF. Remarkably, at the GATA-2 gene, which is repressed by GATA-1, interaction with FOG-1 was dispensable for GATA-1 occupancy and was required for transcriptional inhibition and histone deacetylation. These results indicate that FOG-1 employs distinct mechanisms when cooperating with GATA-1 during transcriptional activation and repression.

Footnotes

↵ ‡ To whom correspondence should be addressed. E-mail: blobel{at}email.chop.edu.
This paper was submitted directly (Track II) to the PNAS office.
Abbreviations: FOG-1, friend of GATA-1; HS, DNase I-hypersensitive site; LCR, locus control region; CBP, cAMP response element-binding protein binding protein; ER, estrogen receptor; ChIP, chromatin immunoprecipitation; acH3, diacetyl-H3; acH4, tetraacetyl-H4.