GATA-6 Activates Transcription of Thyroid Transcription Factor-1*
- From the Children’s Hospital Medical Center, Division of Pulmonary Biology, Cincinnati, Ohio 45229-3039
Abstract
Thyroid transcription factor-1 (TTF-1) is expressed in respiratory epithelial cells, where it regulates the transcription of target genes expressed in a cell-selective manner. GATA-5 and -6, members of the zinc finger family of transcription factors, are also expressed in various cell types within in the developing lung. In the present work, GATA-6 mRNA was detected in adult mouse lung, purified mouse type II epithelial cells, and differentiated mouse pulmonary adenocarcinoma cells (MLE-15 cells), being co-expressed with TTF-1 mRNA. In order to test whether GATA factors regulated TTF-1 gene transcription, GATA-5 and -6 expression vectors were co-transfected with TTF-1 luciferase expression vector. GATA-6, but not GATA-5, markedly activated TTF-1 gene transcription in HeLa cells. EMSA and supershift analysis with GATA-6 antiserum demonstrated that GATA-6 in MLE-15 cell nuclear extracts bound to an element located 96–101 base pairs from major start of TTF-1 gene transcription. Site directed mutagenesis of the GATA element in the TTF-1 promoter region inhibited transactivation by GATA-6 in HeLa cells. GATA-6 is co-expressed with TTF-1 in the respiratory epitheliumin vivo and respiratory epithelial cells in vitro. GATA-6 strongly enhanced activity of the human TTF-1 gene promoter in vitro. These findings support the concept that GATA-6 may play an important role in lung cell differentiation and gene expression, at least in part by altering the expression of TTF-1 and its potential targets.
Footnotes
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↵* This work was supported by Grant HL56387 (to J. A. W.), Perinatology Training Grant 5T32 HD07200, and CFF-RDP R457 (to J. S.-W.).The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵‡ To whom correspondence should be addressed: Children’s Hospital Medical Center, Division of Pulmonary Biology, 3333 Burnet Ave., Cincinnati, OH 45229-3039. Tel.: 513-636-4830; Fax: 513-636-7868; E-mail: whitj0{at}chmcc.org.
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↵2 J. R. Shaw-White, M. D. Bruno, and J. A. Whitsett, unpublished observations.
- Abbreviations:
- TTF
-
thyroid transcription factor
- mTTF
-
mouse TTF
- EMSA
-
electrophoretic gel shift assay
- SP-A
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-B, and -C, surfactant protein A, B, and C, respectively
- CCSP
-
Clara cell secretory protein
- kb
-
kilobase pair(s)
- bp
-
base pair(s)
- CMV
-
cytomegalovirus
- HNF
-
hepatocyte nuclear factor.
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- Received June 3, 1998.
- Revision received October 17, 1998.
- The American Society for Biochemistry and Molecular Biology, Inc.
