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Thyroglobulin gene expression is regulated by insulin and insulin-like growth factor I, as well as thyrotropin, in FRTL-5 thyroid cells.
No full textExpression of the microsomal antigen on the surface of continuously cultured rat thyroid cells is modulated by thyrotropin.
No full textThe thyroid microsomal antigen, commonly implicated in thyroid autoimmune diseases, is not confined to cytoplasm, but is also present on the surface of human thyroid cells in primary culture. In this study, a strain of differentiated rat thyroid cells (FRTL5) grown in continuous culture was used to investigate the relationship between functional status of the thyroid cell and expression of microsomal antigen on its surface. Sera from eight patients with Hashimoto's thyroiditis, one with idiopathic hypothyroidism, and three with hyperthyroid Graves' disease were selected for the presence of microsomal antibody, but undetectable thyroglobulin antibody. One additional serum sample from a patient with Graves' disease, which was negative for both thyroid antibodies was used. Sera from eight normal subjects were used as controls. Indirect immunofluorescence was applied to FRTL5 cells that were viable or fixed with acetone in order to expose intracellular antigens. When FRTL5 cells were cultured in Coon's medium containing TSH (300 microU/ml), positive indirect immunofluorescence surface staining was observed with sera containing microsomal antibody, but not with control sera or with the Graves' serum negative for microsomal antibody. A rough correlation was found between the intensity of the surface fluorescence and microsomal antibody titer. After acetone treatment, microsomal antibody-positive sera produced typical cytoplasmic staining. When FRTL5 cells were cultured in the absence of TSH, disappearance of the surface fluorescence and reduction of the cytoplasmic microsomal antigen occurred. Readdition of TSH progressively restored both the surface and cytoplasmic microsomal antigen. The present data indicate that the thyroid microsomal antigen is represented on the surface of FRTL5 cells, and its expression is modulated by TSH
Association of the changes in cytosolic Ca2+ and iodide efflux induced by thyrotropin and by the stimulation of alpha 1-adrenergic receptors in cultured rat thyroid cells
No full textGanglioside dependent return of TSH receptor function in a rat thyroid tumor with a TSH receptor defect.
No full textThe 1-8 rat thyroid tumor line with a thyrotropin and cholera toxin receptor defect and a deficiency in higher order membrane gangliosides is shown to regain both receptor functions with the in vivo resynthesis or the in vitro reconstitution of higher order gangliosides. Reconstitution was achieved by exposing primary cell cultures of the tumor to preparations of gangliosides from thyroid cells with functional thyrotropin receptor activity
Bovine thyroglobulin. 27 S iodoprotein interactions with thyroid membranes and formation of a 27 S iodoprotein in vitro.
No full text
Expression of the microsomal antigen on the surface of continuously cultured rat thyroid cells is modulated by thyrotropin.
No full textThe thyroid microsomal antigen, commonly implicated in thyroid autoimmune diseases, is not confined to cytoplasm, but is also present on the surface of human thyroid cells in primary culture. In this study, a strain of differentiated rat thyroid cells (FRTL5) grown in continuous culture was used to investigate the relationship between functional status of the thyroid cell and expression of microsomal antigen on its surface. Sera from eight patients with Hashimoto's thyroiditis, one with idiopathic hypothyroidism, and three with hyperthyroid Graves' disease were selected for the presence of microsomal antibody, but undetectable thyroglobulin antibody. One additional serum sample from a patient with Graves' disease, which was negative for both thyroid antibodies was used. Sera from eight normal subjects were used as controls. Indirect immunofluorescence was applied to FRTL5 cells that were viable or fixed with acetone in order to expose intracellular antigens. When FRTL5 cells were cultured in Coon's medium containing TSH (300 microU/ml), positive indirect immunofluorescence surface staining was observed with sera containing microsomal antibody, but not with control sera or with the Graves' serum negative for microsomal antibody. A rough correlation was found between the intensity of the surface fluorescence and microsomal antibody titer. After acetone treatment, microsomal antibody-positive sera produced typical cytoplasmic staining. When FRTL5 cells were cultured in the absence of TSH, disappearance of the surface fluorescence and reduction of the cytoplasmic microsomal antigen occurred. Readdition of TSH progressively restored both the surface and cytoplasmic microsomal antigen. The present data indicate that the thyroid microsomal antigen is represented on the surface of FRTL5 cells, and its expression is modulated by TSH
Multicomponent structure of the thyrotropin receptor: relationship to Graves' disease.
No full textThe thyrotropin receptor is proposed to contain both a glycoprotein and a ganglioside component. Monoclonal antibodies have been developed against soluble thyroid TSH receptor preparations and using Graves' lymphocytes. These show that initial recognition of thyrotropin requires the glycoprotein component, but that monoclonal antibodies to this component block thyrotropin function (blocking antibodies) rather than mimic thyrotropin. Monoclonal antibodies which stimulate thyroid activity in cultured cell systems (cAMP increase) or mouse bioassays, all interact with gangliosides. Using monoclonal antibodies to the glycoprotein component of the thyrotropin receptor, we show that two protein bands, molecular weights 18,000-23,000 and 50,000-55,000, are precipitated from detergent-solubilized preparations. Using a crosslinking procedure with 125I-labeled thyrotropin, we show that thyrotropin binding is related to the disappearance of the 18,000-23,000 molecular weight band on sodium dodecylsulfate gels and the appearance of a 30,000-33,000 molecular weight thyrotropin-membrane component complex. Higher molecular weight thyrotropin-membrane complexes of 75,000-80,000 and 250,000 are visualized when binding studies are performed at pH 7.4 in physiologic medium; larger amounts of the 30,000-33,000 complex are evident at pH 6.0 in a low salt medium. It is thus proposed that the glycoprotein component of the thyrotropin receptor is composed of two subunits with apparent molecular weights of 18,000-23,000 and 50,000-55,000; that the 18,000-23,000 subunit interacts with thyrotropin; and that different receptor subunits can exist depending on in vitro binding conditions. Using monoclonal-stimulating antibodies or natural autoimmune IgG preparations from patients' sera, we show that stimulating antibodies exhibit species-specific binding to human thyroid ganglioside preparations. Individual components or determinants of the thyrotropin receptor structure with specific autoimmune immunoglobulins
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