scholarly journals Bacterial Lipopolysaccharide Stimulates the Thyrotropin-Dependent Thyroglobulin Gene Expression at the Transcriptional Level by Involving the Transcription Factors Thyroid Transcription Factor-1 and Paired Box Domain Transcription Factor 8

Endocrinology ◽  
2006 ◽  
Vol 147 (7) ◽  
pp. 3260-3275 ◽  
Author(s):  
María L. Vélez ◽  
Eugenia Costamagna ◽  
Edna T. Kimura ◽  
Laura Fozzatti ◽  
Claudia G. Pellizas ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Tandem Repeats ◽  
Bacterial Lipopolysaccharide ◽  
Thyroid Cell ◽  
Transcriptional Level ◽  
Thyroid Cells ◽  
Thyroid Transcription Factor ◽  
Thyroid Autoantigens ◽  
Rat Thyroid

The bacterial lipopolysaccharide (LPS) is a biological activator that induces expression of multiple genes in several cell types. LPS has been proposed as an etiopathogenic agent in autoimmune diseases. However, whether LPS affects the expression of autoantigens has not been explored. Thyroglobulin (TG) is a key protein in thyroid hormonogenesis and one of the major thyroid autoantigens. This study aimed to analyze the action of LPS on TG gene expression in Fisher rat thyroid cell line FRTL-5 thyroid cells. We demonstrate that LPS increases the TSH-induced TG protein and mRNA level. Evidence that the effect of LPS is exerted at the transcriptional level was obtained by transfecting the minimal TG promoter. The C element of the TG promoter, which contains sequences for paired box domain transcription factor 8 (Pax8) and thyroid transcription factor (TTF)-1 binding, is essential for full TG promoter expression under TSH stimulation. The transcriptional activity of a construct containing five tandem repeats of the C site is increased by LPS, indicating a possible involvement of the C site in the LPS-induced TG gene transcription. We demonstrate that the TG promoter mutated at the Pax8 or TTF-1 binding element in the C site does not respond to LPS. In band shift assays, binding of Pax8 and TTF-1 to the C site is increased by LPS. The Pax8 and TTF-1 mRNA and protein levels are augmented by LPS. The half-lives of TG, Pax8, and TTF-1 are increased in endotoxin-treated cells. Our results reveal the ability of LPS to stimulate the expression of TG, a finding of potential pathophysiological implication.

scholarly journals Hormonal control of the transcription factor Pax8 and its role in the regulation of thyroglobulin gene expression in thyroid cells

2002 ◽  
Vol 172 (1) ◽  
pp. 163-176 ◽  
Author(s):  
A Mascia ◽  
L Nitsch ◽  
R Di Lauro ◽  
M Zannini
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
De Novo ◽  
Hormonal Control ◽  
Thyroid Cell ◽  
Transcriptional Level ◽  
Thyroid Cells ◽  
Tsh Regulation ◽  
Pax8 Expression ◽  
Rat Thyroid

The transcription factor Pax8 plays an important role in the expression of the differentiated phenotype of thyroid follicular cells. It has recently been shown that Pax8 is necessary for thyroglobulin (Tg) gene expression in the fully differentiated rat thyroid cell line PC. We have used the PC model system to investigate the role of Pax8 as a mediator of TSH regulation of Tg gene expression. We have demonstrated that Pax8 expression, as well as Tg expression, is severely reduced in cells grown in the absence of hormones and serum. The re-addition of TSH or forskolin to the culture medium is able to restore to wild-type levels the expression of both Pax8 and Tg. We have determined that the action of TSH/forskolin on Pax8 is at the transcriptional level. However, the re-expression of Pax8 can be observed several hours before that of Tg, suggesting that either another factor is needed or that Pax8 itself must be post-translationally modified by a newly synthesized protein to become active. To distinguish between these two possibilities we have stably transfected into PC cells an exogenous Pax8 that is expressed independently of TSH. Our results indicate that in these cells the Tg promoter is still dependent on TSH despite the constitutive presence of Pax8. Furthermore, we also show that in this condition Tg gene transcription requires de novo protein synthesis. In conclusion, TSH regulates the expression of Pax8 at a transcriptional level and also regulates the activity of Pax8 by controlling the expression of one or more as yet unknown factors.

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

scholarly journals Rab1b overexpression modifies Golgi size and gene expression in HeLa cells and modulates the thyrotrophin response in thyroid cells in culture

2013 ◽  
Vol 24 (5) ◽  
pp. 617-632 ◽  
Author(s):  
Nahuel Romero ◽  
Catherine I. Dumur ◽  
Hernán Martinez ◽  
Iris A. García ◽  
Pablo Monetta ◽  
...  
Keyword(s):  
Gene Expression ◽  
Hela Cells ◽  
Membrane Trafficking ◽  
Mitogen Activated Protein Kinase ◽  
Thyroid Cell ◽  
Transcriptional Level ◽  
Rab Gtpase ◽  
Mrna Levels ◽  
Consensus Binding Site ◽  
Thyroid Cells

Rab1b belongs to the Rab-GTPase family that regulates membrane trafficking and signal transduction systems able to control diverse cellular activities, including gene expression. Rab1b is essential for endoplasmic reticulum–Golgi transport. Although it is ubiquitously expressed, its mRNA levels vary among different tissues. This work aims to characterize the role of the high Rab1b levels detected in some secretory tissues. We report that, in HeLa cells, an increase in Rab1b levels induces changes in Golgi size and gene expression. Significantly, analyses applied to selected genes, KDELR3, GM130 (involved in membrane transport), and the proto-oncogene JUN, indicate that the Rab1b increase acts as a molecular switch to control the expression of these genes at the transcriptional level, resulting in changes at the protein level. These Rab1b-dependent changes require the activity of p38 mitogen-activated protein kinase and the cAMP-responsive element-binding protein consensus binding site in those target promoter regions. Moreover, our results reveal that, in a secretory thyroid cell line (FRTL5), Rab1b expression increases in response to thyroid-stimulating hormone (TSH). Additionally, changes in Rab1b expression in FRTL5 cells modify the specific TSH response. Our results show, for the first time, that changes in Rab1b levels modulate gene transcription and strongly suggest that a Rab1b increase is required to elicit a secretory response.

scholarly journals Poly(ADP-ribose) polymerase 1 binds to Pax8 and inhibits its transcriptional activity

2008 ◽  
Vol 41 (5) ◽  
pp. 379-388 ◽  
Author(s):  
Tina Di Palma ◽  
Tiziana de Cristofaro ◽  
Chiara D'Ambrosio ◽  
Dolores Del Prete ◽  
Andrea Scaloni ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Fusion Protein ◽  
Transcriptional Activity ◽  
Cell Extract ◽  
Specific Gene ◽  
Thyroid Cell ◽  
Multiprotein Complex ◽  
Thyroid Cells

Pax8 is a transcription factor that plays an important role in the regulation of genes that are exclusively expressed in differentiated thyroid cells. In the thyroid cell environment, evidence exists that Pax8 is part of a multiprotein complex in which its transcriptional activity may be modulated by specific co-factors. In an attempt to identify proteins that interact with Pax8, we performed pull-down experiments challenging the GST–Pax8 fusion protein with protein extracts prepared from the thyroid differentiated cell line PC Cl3. By this approach, we isolated a 113-kDa protein that is able to associate with Pax8, which was further identified by mass fingerprint experiments as poly(ADP-ribose) polymerase 1 (PARP1). To further confirm this interaction, we also showed that PARP1 can be co-immunoprecipitated with Pax8 in vivo from a thyroid cell extract. Gel shifts experiments demonstrated that PARP1 binding to Pax8 significantly inhibits Pax8 binding to DNA. Accordingly, we provide evidence that the functional outcome of such an interaction is a significant downregulation of Pax8 transcriptional activity. In the context of thyroid-specific gene transcription, our results suggest that PARP1 behaves as an important negative co-factor involved in the regulation of Pax8-dependent gene expression.

scholarly journals Inhibition of HMGI-C protein synthesis suppresses retrovirally induced neoplastic transformation of rat thyroid cells.

1995 ◽  
Vol 15 (3) ◽  
pp. 1545-1553 ◽  
Author(s):  
M T Berlingieri ◽  
G Manfioletti ◽  
M Santoro ◽  
A Bandiera ◽  
R Visconti ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Cell Transformation ◽  
Thyroid Cell ◽  
Transcriptional Level ◽  
Thyroid Cells ◽  
C Protein ◽  
Group I ◽  
Sarcoma Virus ◽  
Rat Thyroid ◽  
Antisense Construct

Elevated expression of the three high-mobility group I (HMGI) proteins (HMGI, HMGY, and HMGI-C) has previously been correlated with the presence of a highly malignant phenotype in epithelial and fibroblastic rat thyroid cells and in experimental thyroid, lung, mammary, and skin carcinomas. Northern (RNA) blot and run-on analyses demonstrated that the induction of HMGI genes in transformed thyroid cells occurs at the transcriptional level. An antisense methodology to block HMGI-C protein synthesis was then used to analyze the role of this protein in the process of thyroid cell transformation. Transfection of an antisense construct for the HMGI-C cDNA into normal thyroid cells, followed by infection with transforming myeloproliferative sarcoma virus or Kirsten murine sarcoma virus, generated cell lines that expressed significant levels of the retroviral transforming oncogenes v-mos or v-ras-Ki and removed the dependency on thyroid-stimulating hormones. However, in contrast with untransfected cells or cells transfected with the sense construct, those containing the antisense construct did not demonstrate the appearance of any malignant phenotypic markers (growth in soft agar and tumorigenicity in athymic mice). A great reduction of the HMGI-C protein levels and the absence of the HMGI(Y) proteins was observed in the HMGI-C antisense-transfected, virally infected cells. Therefore, the HMGI-C protein seems to play a key role in the transformation of these thyroid cells.

scholarly journals A Novel Thyroid Transcription Factor Is Essential for Thyrotropin-Induced Up-Regulation of Na+/I− Symporter Gene Expression

1998 ◽  
Vol 12 (5) ◽  
pp. 727-736 ◽  
Author(s):  
Masayuki Ohmori ◽  
Toyoshi Endo ◽  
Norikazu Harii ◽  
Toshimasa Onaya
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Mobility Shift ◽  
Thyroid Cells ◽  
Thyroid Transcription Factor 1 ◽  
Nuclear Extracts ◽  
Thyroid Transcription Factor ◽  
Nis Gene ◽  
Responsive Element ◽  
Gel Mobility Shift

Abstract The stimulation of iodide (I−) transport by TSH in FRTL-5 thyroid cells is partly due to an increase in Na+/I− symporter (NIS) gene expression. The identification of a TSH-responsive element (TRE) in the NIS promoter and its relationship to the action of thyroid transcription factor-1 (TTF-1) on the promoter are the subjects of this report. By transfecting NIS promoter-luciferase chimeric plasmids into FRTL-5 cells in the presence or absence of TSH, we identify a TRE between −420 and −370 bp of the NIS 5′-flanking region. Nuclear extracts from FRTL-5 cells cultured in the absence of TSH form two groups of protein-DNA complexes, A and B, in gel mobility shift assays using an oligonucleotide having the sequence from −420 to −385 bp. Only the A complex is increased by exposure of FRTL-5 cells to TSH or forskolin. The addition of TSH to FRTL-5 cells can increase the A complex at 3–6 h, reaching a maximum at 12 h. FRTL-5, but not nonfunctioning FRT thyroid or Buffalo rat liver (BRL) cell nuclear extracts, form the A complex. The TSH-increased nuclear factor in FRTL-5 cells interacting with the NIS TRE is distinct from TTF-1, thyroid transcription factor-2, or Pax-8, as evidenced by the absence of competition using oligonucleotides specific for these factors in gel shift assays. Neither is it the nuclear protein interacting with cAMP response element. The TRE is in the upstream of a TTF-1-binding site,− 245 to −230 bp. Mutation of the TRE causing a loss of TSH responsiveness also decreases TTF-1-induced promoter activity in a transfection experiment. The formation of the A complex between FRTL-5 nuclear extracts and the NIS TRE is redox-regulated. In sum, TSH/cAMP-induced up-regulation of the NIS requires a novel thyroid transcription factor, which also appears to be involved in TTF-1-mediated thyroid-specific NIS gene expression.

scholarly journals Trace Amine-Associated Receptor 1 Trafficking to Cilia of Thyroid Epithelial Cells

Cells ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1518
Author(s):  
Maria Qatato ◽  
Vaishnavi Venugopalan ◽  
Alaa Al-Hashimi ◽  
Maren Rehders ◽  
Aaron D. Valentine ◽  
...  
Keyword(s):  
Cell Surface ◽  
Cell Lines ◽  
Human Thyroid ◽  
Apical Plasma Membrane ◽  
Thyroid Cell ◽  
Thyroid Cells ◽  
Trace Amine ◽  
Rat Thyroid

Trace amine-associated receptor 1 (rodent Taar1/human TAAR1) is a G protein-coupled receptor that is mainly recognized for its functions in neuromodulation. Previous in vitro studies suggested that Taar1 may signal from intracellular compartments. However, we have shown Taar1 to localize apically and on ciliary extensions in rodent thyrocytes, suggesting that at least in the thyroid, Taar1 may signal from the cilia at the apical plasma membrane domain of thyrocytes in situ, where it is exposed to the content of the follicle lumen containing putative Taar1 ligands. This study was designed to explore mouse Taar1 (mTaar1) trafficking, heterologously expressed in human and rat thyroid cell lines in order to establish an in vitro system in which Taar1 signaling from the cell surface can be studied in future. The results showed that chimeric mTaar1-EGFP traffics to the apical cell surface and localizes particularly to spherical structures of polarized thyroid cells, procilia, and primary cilia upon serum-starvation. Moreover, mTaar1-EGFP appears to form high molecular mass forms, possibly homodimers and tetramers, in stably expressing human thyroid cell lines. However, only monomeric mTaar1-EGFP was cell surface biotinylated in polarized human thyrocytes. In polarized rat thyrocytes, mTaar1-EGFP is retained in the endoplasmic reticulum, while cilia were reached by mTaar1-EGFP transiently co-expressed in combination with an HA-tagged construct of the related mTaar5. We conclude that Taar1 trafficking to cilia depends on their integrity. The results further suggest that an in vitro cell model was established that recapitulates Taar1 trafficking in thyrocytes in situ, in principle, and will enable studying Taar1 signaling in future, thus extending our general understanding of its potential significance for thyroid autoregulation.

Extinction and activation of the thyroglobulin promoter in hybrids of differentiated and transformed thyroid cells

1990 ◽  
Vol 10 (3) ◽  
pp. 1033-1040
Author(s):  
I M Bonapace ◽  
M Sanchez ◽  
S Obici ◽  
A Gallo ◽  
S Garofalo ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Lines ◽  
Selectable Marker ◽  
Hybrid Cell ◽  
Transformed Cells ◽  
Thyroid Cells ◽  
Dominant Selectable Marker ◽  
Thyroglobulin Gene ◽  
Rat Thyroid ◽  
Hybrid Cell Lines

Thyroglobulin gene expression was repressed in a rat thyroid cell line transformed with Kirsten murine sarcoma virus. Expression of a dominant selectable marker driven by the thyroglobulin promoter was also inhibited. Somatic cell hybridization of transformed and differentiated thyroid cells resulted in extinction of thyroglobulin gene expression. When transformed cells carrying a dominant selectable marker driven by the thyroglobulin promoter were fused to differentiated cells and expression of this marker was selected, we obtained stable hybrid cell lines expressing both the endogenous and the exogenous thyroglobulin promoters. Although the expression of v-ras remained unchanged compared with expression in the parental transformed cells, transformation was suppressed in the hybrid cell lines. The other thyroid differentiation markers, iodide uptake and thyroid-stimulating hormone-dependent growth, were inhibited in all the hybrids tested. We show that activity of the thyroglobulin promoter correlates with the presence of a thyroid nuclear factor that binds the promoter at position -60 from the transcription start site. Loss of this factor accompanies the extinction of thyroglobulin gene expression in hybrids selected for expression of a non-thyroid-specific promoter.

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