scholarly journals Hepatocyte nuclear factor 3 activates transcription of thyroid transcription factor 1 in respiratory epithelial cells.

1996 ◽  
Vol 16 (7) ◽  
pp. 3626-3636 ◽  
Author(s):  
K Ikeda ◽  
J R Shaw-White ◽  
S E Wert ◽  
J A Whitsett
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Family Members ◽  
Nuclear Proteins ◽  
Nuclear Factor ◽  
Hepatocyte Nuclear Factor ◽  
Thyroid Transcription Factor 1 ◽  
Thyroid Transcription Factor ◽  
Respiratory Epithelial ◽  
Transcription Factor 1

Thyroid transcription factor 1 (TTF-1), hepatocyte nuclear factor 3alpha (HNF-3alpha), and HNF-3beta regulate the transcription of genes expressed in the respiratory epithelium. To test whether members of the HNF-3/forkhead family influence TTF-1 gene expression, deletion constructs containing the 5' region of the human TTF-1 gene were transfected into immortalized mouse lung epithelial (MLE) cells. DNase I protection and electrophoretic mobility shift assays identified elements in the 5' region of the TTF-1 gene that bound MLE cell nuclear proteins consistent with the binding of HNF-3 to sites at positions -135 to -124 and -14 to -3. In MLE cells, TTF-1-luciferase reporter constructs were activated by cotransfection with HNF-3beta, activated to a lesser extent by HNF-3alpha, but not activated by HFH-8. HNF-3alpha. and HFH-8 inhibited the activation of TTF-1-luciferase by HNF-3beta. Site-specific mutagenesis of each of the HNF-3 binding sites in the human TTF-1 gene inhibited the binding of MLE cell nuclear proteins and inhibited transactivation of the TTF-1-luciferase constructs after cotransfection with HNF-3beta. Immunohistochemical staining demonstrated that both HNF-3beta and TTF-1 were detected in bronchiolar and alveolar type II cells in the human lung. Modulation of TTF-1 gene expression by members of the HNF-3/forkhead family members may provide a mechanism by which distinct HNF-3/forkhead family members influence respiratory epithelial cell gene expression and cell differentiation.

scholarly journals Thyroglobulin Repression of Thyroid Transcription Factor 1 (TTF-1) Gene Expression Is Mediated by Decreased DNA Binding of Nuclear Factor I Proteins Which Control Constitutive TTF-1 Expression

2000 ◽  
Vol 20 (22) ◽  
pp. 8499-8512 ◽  
Author(s):  
Minoru Nakazato ◽  
Hyun-Kyung Chung ◽  
Luca Ulianich ◽  
Antonino Grassadonia ◽  
Koichi Suzuki ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Transcription Factors ◽  
Nuclear Factor ◽  
Factor I ◽  
Thyroid Transcription Factor 1 ◽  
Nuclear Extracts ◽  
Thyroid Transcription Factor ◽  
Nuclear Factor I ◽  
Transcription Factor 1

ABSTRACT Follicular thyroglobulin (TG) selectively suppresses the expression of thyroid-restricted transcription factors, thereby altering the expression of thyroid-specific proteins. In this study, we investigated the molecular mechanism by which TG suppresses the prototypic thyroid-restricted transcription factor, thyroid transcription factor 1 (TTF-1), in rat FRTL-5 thyrocytes. We show that the region between bp −264 and −153 on the TTF-1 promoter contains two nuclear factor I (NFI) elements whose function is involved in TG-mediated suppression. Thus, NFI binding to these elements is critical for constitutive expression of TTF-1; TG decreases NFI binding to the NFI elements in association with TG repression. NFI is a family of transcription factors that is ubiquitously expressed and contributes to constitutive and cell-specific gene expression. In contrast to the contribution of NFI proteins to constitutive gene expression in other systems, we demonstrate that follicular TG transcriptionally represses all NFI RNAs (NFI-A, -B, -C, and -X) in association with decreased NFI binding and that the RNA levels decrease as early as 4 h after TG treatment. Although TG treatment for 48 h results in a decrease in NFI protein-DNA complexes measured in DNA mobility shift assays, NFI proteins are still detectable by Western analysis. We show, however, that the binding of all NFI proteins is redox regulated. Thus, diamide treatment of nuclear extracts strongly reduces the binding of NFI proteins, and the addition of higher concentrations of dithiothreitol to nuclear extracts from TG-treated cells restores NFI-DNA binding to levels in extracts from untreated cells. We conclude that NFI binding to two NFI elements, at bp −264 to −153, positively regulates TTF-1 expression and controls constitutive TTF-1 levels. TG mediates the repression of TTF-1 gene expression by decreasing NFI RNA and protein levels, as well as by altering the binding activity of NFI, which is redox controlled.

scholarly journals Modulation of Thyroid-Specific Gene Expression in Normal and Nodular Human Thyroid Tissues from Adults: An in Vivo Effect of Thyrotropin

2005 ◽  
Vol 90 (10) ◽  
pp. 5692-5697 ◽  
Author(s):  
Rocco Bruno ◽  
Elisabetta Ferretti ◽  
Emanuele Tosi ◽  
Franco Arturi ◽  
Paolo Giannasio ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Human Thyroid ◽  
Normal Tissues ◽  
Thyroid Transcription Factor 1 ◽  
Thyroid Transcription Factor ◽  
Group 2 ◽  
Transcription Factor 1 ◽  
Tsh Levels

Context: Evidence from in vitro studies or animal models has shown that TSH affects thyrocytes by thyroid-specific expression modulation. Objective: The objective of our study was to analyze the role of TSH in human thyroid gene expression in vivo. Design/Setting: Thirty-nine normal thyroid tissues were collected at the same center. Study Subjects: Patients were divided into two groups based on serum TSH levels: 17 with normal TSH levels (1–4 mU/liter; group 1) and 22 with TSH levels below 0.5 mU/liter (group 2). Intervention: Group 2 underwent thyroidectomy after suppressive l-T4 therapy. Main Outcome Measures: mRNA levels of thyroid genes such as sodium/iodide symporter (NIS), apical iodide transporter, pendrin, thyroglobulin, thyroperoxidase, TSH receptor, paired box transcription factor 8, and thyroid transcription factor-1 were evaluated by quantitative PCR. Results: The reduction of TSH stimulation causes decreases in NIS and apical iodide transporter gene expression in normal tissues and more limited reductions in thyroglobulin, thyroperoxidase, and paired box transcription factor 8, but it has no significant effect on TSH receptor, pendrin, or thyroid transcription factor-1. Comparison of NIS levels in normal and nodular tissues from the same patient confirmed that it is differentially expressed in nodules only in the presence of normal TSH (P < 0.01). In patients with suppressed TSH, nodular NIS levels were similar to those in normal tissues. Conclusions: Our data represent the first demonstration in human thyroid tissues that TSH contributes to the regulation of thyrocyte differentiation by modulating thyroid gene levels. It exerts a particularly important effect on the transcription of NIS, which becomes very low after prolonged TSH suppression.

Disrupted co-ordination of Pax-8 and thyroid transcription factor-1 gene expression in a dedifferentiated rat thyroid tumour cell line derived from FRTL-5

1996 ◽  
Vol 150 (3) ◽  
pp. 377-382 ◽  
Author(s):  
C J H van der Kallen ◽  
D C J Spierings ◽  
J H H Thijssen ◽  
M A Blankenstein ◽  
T W A de Bruin
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Cell Line ◽  
Thyroid Peroxidase ◽  
Wild Type ◽  
Specific Expression ◽  
Thyroid Transcription Factor 1 ◽  
Thyroid Transcription Factor ◽  
Rat Thyroid ◽  
Transcription Factor 1

Abstract The mutant rat thyroid cell line FRTL-5/TA, isolated from a non-functional tumour which originated spontaneously from wild-type FRTL-5 cells, shows autonomous TSH-independent growth and loss of the thyroid-specific phenotype, lacking thyroid-specific expression of thyroglobulin (Tg) and thyroid peroxidase (TPO) genes. To investigate the role of the transcription factors Pax-8 and thyroid transcription factor-1 (TTF-1) in rat thyroid tumorigenesis, RNA expression of these two thyroid-specific nuclear factors was measured in FRTL-5/TA tumour cells and compared with the expression in wild-type FRTL-5 cells. TTF-1 gene expression was similar to that in wild-type FRTL-5, and showed a similar down-regulation after stimulation with TSH. The finding suggested normal TTF-1 mRNA and protein expression in both cell lines. By contrast, Pax-8 mRNA transcript signal was markedly reduced in FRTL-5/TA cells, reaching levels as low as 8% of the normal, basal level in FRTL-5 cells. These data indicated that the loss of thyroid-specific expression of Tg and TPO genes in FRTL-5/TA cells was not related to changes in TTF-1 gene expression but rather to reduced Pax-8 gene expression. It was concluded that a disruption of the co-ordinated expression of TTF-1 and Pax-8 is implicated in the loss of thyroid phenotype of FRTL-5/TA cells in terms of reduced Tg and TPO expression. Journal of Endocrinology (1996) 150, 377–382

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