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Mol. Cell. Biol., Jun 1995, 3147-3153, Vol 15, No. 6
GA Blobel, CA Sieff and SH Orkin
High-dose estrogen administration induces anemia in mammals. In chickens,
estrogens stimulate outgrowth of bone marrow-derived erythroid progenitor
cells and delay their maturation. This delay is associated with
down-regulation of many erythroid cell-specific genes, including alpha- and
beta-globin, band 3, band 4.1, and the erythroid cell-specific histone H5.
We show here that estrogens also reduce the number of erythroid progenitor
cells in primary human bone marrow cultures. To address potential
mechanisms by which estrogens suppress erythropoiesis, we have examined
their effects on GATA-1, an erythroid transcription factor that
participates in the regulation of the majority of erythroid cell-specific
genes and is necessary for full maturation of erythrocytes. We demonstrate
that the transcriptional activity of GATA-1 is strongly repressed by the
estrogen receptor (ER) in a ligand-dependent manner and that this
repression is reversible in the presence of 4-hydroxytamoxifen. ER-mediated
repression of GATA-1 activity occurs on an artificial promoter containing a
single GATA- binding site, as well as in the context of an intact promoter
which is normally regulated by GATA-1. GATA-1 and ER bind to each other in
vitro in the absence of DNA. In coimmunoprecipitation experiments using
transfected COS cells, GATA-1 and ER associate in a ligand-dependent
manner. Mapping experiments indicate that GATA-1 and the ER form at least
two contacts, which involve the finger region and the N-terminal activation
domain of GATA-1. We speculate that estrogens exert effects on
erythropoiesis by modulating GATA-1 activity through protein-protein
interaction with the ER.(ABSTRACT TRUNCATED AT 250 WORDS)
Copyright © 1995, American Society for Microbiology
Ligand-dependent repression of the erythroid transcription factor GATA- 1 by the estrogen receptor
Division of Hematology/Oncology, Children's Hospital, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA.
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