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

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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Iodide symporter gene expression in normal and transformed rat thyroid cells

Acta Endocrinologica ◽

10.1530/eje.0.1400447 ◽

1999 ◽

pp. 447-451 ◽

Cited By ~ 42

Author(s):

F Trapasso ◽

R Iuliano ◽

E Chiefari ◽

F Arturi ◽

A Stella ◽

...

Keyword(s):

Gene Expression ◽

Cell Lines ◽

Inhibitory Effect ◽

Mrna Levels ◽

Iodide Uptake ◽

Thyroid Cells ◽

Transformed Cell ◽

Nis Gene ◽

Rat Thyroid ◽

Transformed Cell Lines

OBJECTIVE: Decrease or loss of the Na+/I- symporter (NIS) activity profoundly affects the suitability of the use of radioiodine to detect or treat metastatic thyroid tissues. The aim of our study was to verify whether specific oncogene abnormalities were responsible for the alteration in NIS activity in thyroid cells. DESIGN AND METHODS: Expression of the NIS gene was investigated by Northern blot analysis in normal and in some oncogene-transformed cell lines with different degrees of malignancy which had lost the iodide uptake ability. RESULTS: NIS gene expression was up-regulated by TSH in a dose-dependent and time-dependent way in normal PC Cl 3 cells. The same effect was observed by activating the cAMP-dependent pathway by forskolin. Conversely, insulin and 12-O-tetradecanoylphorbol-13-acetate (TPA) showed a partial inhibitory effect on NIS gene expression. The oncogene-transformed cell lines PC v-erbA, PC HaMSV, PC v-raf, and PC E1A cells showed reduced NIS mRNA levels compared with the normal PC Cl 3 cells. Conversely, an almost complete absence of NIS gene expression was found in PC RET/PTC, PC KiMSV, PC p53(143ala), and PC PyMLV cell lines. CONCLUSIONS: Our data show that oncogene activation could play a role in affecting the iodide uptake ability in thyroid tumoral cells; different mechanisms are involved in the oncogene-dependent loss of NIS activity in transformed thyroid cells.

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Genetic analysis of the human Y chromosome by chromosome-mediated gene transfer

Development ◽

10.1242/dev.101.supplement.59 ◽

1987 ◽

Vol 101 (Supplement) ◽

pp. 59-65

Author(s):

Catrin A. Pritchard ◽

Peter N. Goodfellow

Keyword(s):

Gene Transfer ◽

Y Chromosome ◽

Cell Lines ◽

Selectable Marker ◽

Hybrid Cell ◽

Mapping Data ◽

Somatic Cell Genetics ◽

Structural Mapping ◽

Hybrid Cell Lines ◽

Human Y Chromosome

Chromosome-mediated gene transfer (CMGT) can be used to segregate fragments of human chromosomes in human—rodent hybrid cells. As with all somatic cell genetics methods, a selection technique is needed to isolate the hybrid cell lines produced by CMGT. Expression of the MIC2 gene product on the cell surface (the 12E7 antigen) provides an endogenous selectable marker for the human Y chromosome. Using chromosome transfer followed by separation of 12E7 antigen-positive cells on the fluorescence-activated cell sorter, a series of cell lines containing segregated fragments of the Y chromosome have been derived. The possibility of using these fragments to derive fine structural mapping data for the Y chromosome is considered in this review.

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Selectable mutations altering two mechanisms of mammalian K+ transport are dominant

AJP Cell Physiology ◽

10.1152/ajpcell.1987.252.5.c515 ◽

1987 ◽

Vol 252 (5) ◽

pp. C515-C522 ◽

Cited By ~ 2

Author(s):

J. J. Gargus

Keyword(s):

Somatic Cell ◽

Cell Lines ◽

Selectable Marker ◽

Hybrid Cell ◽

Mutant Phenotype ◽

Wild Type ◽

Low Potassium ◽

Cotransport System ◽

Hybrid Cell Lines ◽

K Transport

Somatic cell mutants with altered K+ transport have previously been isolated from mutagenzied LMTK- cells for their ability to grow at subthreshold low-potassium concentrations (0.2 mM). These mutants fall into two classes: one class, LTK-5, possesses a functionally altered furosemide-sensitive Na+-K+-Cl- cotransport system and the other, LTK-1, an altered K+-conducting channel. Somatic cell hybrids have been formed between each of these cell lines and a wild-type L-cell line, making use of complementing selectable marker mutations carried by these parents, to establish the dominance of the K+ transport mutations. Hybrids were isolated and studied in two ways: clonal hybrid cell lines were selected in a manner unbiased toward their K+ transport phenotype, which was later assayed; and the number of independent hybrids arising in this single-selective condition was compared with the number arising in a condition which is double selective for the mutant phenotype as well. By both assays, hybrids formed with LTK-1 or LTK-5 as a parent uniformly exhibited the mutant phenotype by growth and cloning, whereas control hybrids with LMTK- as parent never did. This demonstrates both transport mutations to be dominant and thus potentially isolatable.

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

Cells ◽

10.3390/cells10061518 ◽

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.

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4940782 Monoclonal antibodies against IgE-associated determinants, hybrid cell lines producing these antibodies, and use therefore

Comparative Immunology Microbiology and Infectious Diseases ◽

10.1016/0147-9571(91)90011-2 ◽

1991 ◽

Vol 14 (3) ◽

pp. i

Keyword(s):

Monoclonal Antibodies ◽

Cell Lines ◽

Hybrid Cell ◽

Hybrid Cell Lines

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Transforming growth factor β1 selectively regulates ferritin gene expression in malignant H-ras-transformed fibrosarcoma cell lines

Biochemistry and Cell Biology ◽

10.1139/o00-062 ◽

2000 ◽

Vol 78 (4) ◽

pp. 527-535 ◽

Cited By ~ 3

Author(s):

James Lo ◽

Robert AR Hurta

Keyword(s):

Gene Expression ◽

Cell Proliferation ◽

Growth Factor ◽

Malignant Transformation ◽

Cell Lines ◽

Transforming Growth Factor ◽

Malignant Potential ◽

Transformed Cells ◽

Protein Synthesis Inhibitor ◽

Ferritin Gene

Transforming growth factor β1 is an important growth regulator in many cell types, usually exerting a negative effect on cellular growth. Inhibition of DNA synthesis and cell proliferation is frequently lost during malignant transformation, and in some cases, tumor cell proliferation is actually stimulated by TGF-β1. The present study demonstrates a novel link between alterations in TGF-β1 regulation during malignant conversion, and the expression of ferritin, an important activity involved in a number of biological functions including iron homeostasis and cell-growth control. A series of H-ras-transformed mouse 10 T 1/2 cell lines, exhibiting increasing malignant potential, was investigated for possible TGF-β1-mediated changes in ferritin gene expression. Selective induction of gene expression was observed, since only H-ras-transformed cells with malignant potential exhibited marked elevations in ferritin gene expression, in particular, alterations in H-ferritin gene expression. The regulation of H-ferritin gene expression in response to TGF-β 1 did not involve alterations in transcription, but occurred through mechanisms of post-transcriptional stabilization of the H-ferritin mRNA. Additionally, evidence was obtained for a cycloheximide-sensitive regulator of H-ferritin gene expression, since the presence of this protein synthesis inhibitor increased H-ferritin message levels, and in combination with TGF-β1, cooperated in an additive manner to augment H-ferritin gene expression. These results show for the first time that TGF-β1 can regulate ferritin gene expression in malignant H-ras transformed cells, and suggest a mechanism for growth factor stimulation of malignant cells, in which early alterations in the control of H-ferritin gene expression are important.Key words: TGF-β1, ferritin gene expression, malignant transformation.

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