The functional interaction between the paired domain transcription factor Pax8 and Smad3 is involved in transforming growth factor-β repression of the sodium/iodide symporter gene
| Autor: | Eugenia Costamagna, Pilar Santisteban, Bibian García |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2004 |
| Předmět: |
Transcriptional Activation
Time Factors Transcription Genetic Blotting Western Down-Regulation Thyrotropin SMAD Biology Biochemistry PAX8 Transcription Factor Sp3 transcription factor Genes Reporter Transforming Growth Factor beta Transcription (biology) Gene expression Animals Paired Box Transcription Factors RNA Messenger Smad3 Protein Binding site Luciferases Promoter Regions Genetic Molecular Biology Transcription factor Glutathione Transferase Smad4 Protein Cell Nucleus Dose-Response Relationship Drug Models Genetic Symporters Nuclear Proteins Cell Differentiation DNA Cell Biology Blotting Northern Molecular biology Protein Structure Tertiary Rats DNA-Binding Proteins Gene Expression Regulation Symporter Trans-Activators PAX8 Cell Division Gene Deletion Plasmids Protein Binding |
| Zdroj: | Digital.CSIC. Repositorio Institucional del CSIC instname |
| ISSN: | 1083-351X 0021-9258 |
| Popis: | El pdf del artículo es la versión post-print. Transforming growth factor-β (TGF-β) is a secreted protein that regulates proliferation, differentiation, and death in various cell types, including thyroid cells, although few details are known about its mechanisms of action in this cell type. Here, we studied the role of TGF-β on the regulation of sodium/iodide symporter (NIS) gene expression in PC C13 thyroid cells. TGF-β inhibits thyroid-stimulated hormone (TSH)-induced NIS mRNA and protein levels in a dose-dependent manner. This effect takes place at the transcriptional level, as TGF-β inhibits TSH-induced transcription of a luciferase reporter construct containing a 2.8-kb DNA fragment of the rat NIS promoter. The inhibitory effect of TGF-β was partially overcome by inhibitory Smad7 and mimicked by overexpression of either Smad3 or a constitutively activated mutant of TGF-β receptor I (acALK-5). Using internal deletions of the promoter, we defined a region between -2,841 to -1,941, which includes the NIS upstream enhancer (NUE), as responsible for the TGF-β/Smad inhibitory effect. NUE contains two binding sites for the paired domain transcription factor Pax8, the main factor controlling NIS transcription. The physical interaction observed between Pax8 and Smad3 appears to be responsible for the decrease in Pax8 binding to DNA. Expression of Pax8 mRNA and protein was also decreased by TGF-β treatment. The results suggest that, through activation of Smad3, TGF-β decreases Pax8 DNA binding activity as well as Pax8 mRNA and protein levels, which are at least partially involved in TGF-β-induced down-regulation of NIS gene expression in thyroid follicular cells. Our results thus demonstrate a novel mechanism of Smad3 function in regulating thyroid cell differentiation by functionally antagonizing the action of the paired domain transcription factor Pax8. This study was supported by Ministerio de Ciencia y Tecnología (MCyT) Grant BMC 2001-2087, Comunidad Autónoma de Madrid (CAM) Grant 08.2/0025/97, and Fondo de Investigaciones Sanitarias (FIS) of the Instituto de Salud Carlos III Grants RCMN C03/08 and RGDM G03/212. |
| Databáze: | OpenAIRE |
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