title: The TR2 and TR4 orphan nuclear receptors repress Gata1 transcription.
abstract: When the orphan nuclear receptors TR2 and TR4, the DNA-binding subunits of the DRED repressor complex, are forcibly expressed in erythroid cells of transgenic mice, embryos exhibit a transient mid-gestational anemia as a consequence of a reduction in the number of primitive erythroid cells. GATA-1 mRNA is specifically diminished in the erythroid cells of these TR2/TR4 transgenic embryos as it is in human CD34(+) progenitor cells transfected with forcibly expressed TR2/TR4. In contrast, in loss-of-function studies analyzing either Tr2- or Tr4-germline-null mutant mice or human CD34(+) progenitor cells transfected with force-expressed TR2 and TR4 short hairpin RNAs (shRNAs), GATA-1 mRNA is induced. An evolutionarily conserved direct repeat (DR) element, a canonical binding site for nuclear receptors, was identified in the GATA1 hematopoietic enhancer (G1HE), and TR2/TR4 binds to that site in vitro and in vivo. Mutation of that DR element led to elevated Gata1 promoter activity, and reduced promoter responsiveness to cotransfected TR2/TR4. Thus, TR2/TR4 directly represses Gata1/GATA1 transcription in murine and human erythroid progenitor cells through an evolutionarily conserved binding site within a well-characterized, tissue-specific Gata1 enhancer, thereby providing a mechanism by which Gata1 can be directly silenced during terminal erythroid maturation.
authors.affiliation: Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA.
authors.forename: Osamu
authors.initials: O
authors.lastname: Tanabe
authors.forename: Yannan
authors.initials: Y
authors.lastname: Shen
authors.forename: Qinghui
authors.initials: Q
authors.lastname: Liu
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Campbell
authors.forename: Takashi
authors.initials: T
authors.lastname: Kuroha
authors.forename: Masayuki
authors.initials: M
authors.lastname: Yamamoto
authors.forename: James Douglas
authors.initials: JD
authors.lastname: Engel
mesh_terms: D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D015536:Down-Regulation; D004622:Embryo, Mammalian; D015672:Erythroid Precursor Cells / Q000166:cytology / Q000378:metabolism; D050982:GATA1 Transcription Factor / Q000235:genetics*; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D057107:Nuclear Receptor Subfamily 2, Group C, Member 1; D011485:Protein Binding; D011987:Receptors, Steroid / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D011988:Receptors, Thyroid Hormone / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D020218:Response Elements; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic / Q000235:genetics
chemical_list: D050982:GATA1 Transcription Factor; C494689:Gata1 protein, mouse; C539822:NR2C1 protein, human; C539823:Nr2c1 protein, mouse; C490514:Nr2c2 protein, mouse; D057107:Nuclear Receptor Subfamily 2, Group C, Member 1; D011987:Receptors, Steroid; D011988:Receptors, Thyroid Hormone