title: Essential role of GATA2 in the negative regulation of thyrotropin beta gene by thyroid hormone and its receptors.
abstract: Previously we reported that the negative regulation of the TSHbeta gene by T(3) and its receptor [thyroid hormone receptor (TR)] is observed in CV1 cells when GATA2 and Pit1 are introduced. Using this system, we further studied the mechanism of TSHbeta inhibition. The negative regulatory element (NRE), which had been reported to mediate T(3)-bound TR (T(3)-TR)-dependent inhibition, is dispensable, because deletion or mutation of NRE did not impair suppression. The reporter construct, TSHbeta-D4-chloramphenicol acetyltransferase, which possesses only the binding sites for Pit1 and GATA2, was activated by GATA2 alone, and this transactivation was specifically inhibited by T(3)-TR. The Zn finger region of GATA2 interacts with the DNA-binding domain of TR in a T(3)-independent manner. The suppression by T(3)-TR was impaired by overexpression of a dominant-negative type TR-associated protein (TRAP) 220, an N- and C-terminal deletion construct, indicating the participation of TRAP220. Chromatin immunoprecipitation assays with a thyrotroph cell line, TalphaT1, revealed that T(3) treatment recruited histone deacetylase 3, reduced the acetylation of histone H4, and caused the dissociation of TRAP220 within 15-30 min. The reduction of histone H4 acetylation was transient, whereas the dissociation of TRAP220 persisted for a longer period. In the negative regulation of the TSHbeta gene by T(3)-TR we report that 1) GATA2 is the major transcriptional activator of the TSHbeta gene, 2) the putative NRE previously reported is not required, 3) TR-DNA-binding domain directly interacts with the Zn finger region of GATA2, and 4) histone deacetylation and TRAP220 dissociation are important.
authors.affiliation: Second Division, Department of Internal Medicine, Hamamatsu University School of Medicine, 1-20-1 Handayama, Hamamatsu, Shizuoka 431-3192, Japan.
authors.forename: Akio
authors.initials: A
authors.lastname: Matsushita
authors.forename: Shigekazu
authors.initials: S
authors.lastname: Sasaki
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Kashiwabara
authors.forename: Koji
authors.initials: K
authors.lastname: Nagayama
authors.forename: Kenji
authors.initials: K
authors.lastname: Ohba
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Iwaki
authors.forename: Hiroko
authors.initials: H
authors.lastname: Misawa
authors.forename: Keiko
authors.initials: K
authors.lastname: Ishizuka
authors.forename: Hirotoshi
authors.initials: H
authors.lastname: Nakamura
mesh_terms: D000107:Acetylation; D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D047369:Chromatin Immunoprecipitation; D015536:Down-Regulation; D050989:GATA2 Transcription Factor / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D006657:Histones / Q000378:metabolism; D006801:Humans; D051379:Mice; D011988:Receptors, Thyroid Hormone / Q000378:metabolism*; D050436:Regulatory Elements, Transcriptional / Q000187:drug effects / Q000235:genetics; D037322:Thyrotropin, beta Subunit / Q000037:antagonists & inhibitors* / Q000235:genetics*; D015533:Transcriptional Activation; D014284:Triiodothyronine / Q000378:metabolism*
chemical_list: D050989:GATA2 Transcription Factor; D006657:Histones; D011988:Receptors, Thyroid Hormone; D037322:Thyrotropin, beta Subunit; D014284:Triiodothyronine