ABSTRACT
BACKGROUND: In the previous studies, we identified that the interferon-gamma activated sequence (GAS) in the 5-flanking region of rat ICAM-1 gene is major element for interferon-y-inducible expression of the gene in rat thyroid cells, FRTL-5. We here, investigated the role of transcriptional coactivators, CBP (CREB binding protein) and CIITA (class II transactivator) in the modulation of the activity of GAS which could interacts with signal transducers and activators of transcription-1 and 3 (STAT1 and STAT3). METHODS: The expression of CBP RNA and protein were quantitated in FRTL-5 after stimulation with interferon-y (IFN-gamma), thyroid stimulating hormone (TSH), forskolin and methimazole. Direct association of CBP with STAT were analyzed by irnmunoprecipitation. The transcriptional roles of CBP and CIITA in the regulation of GAS were assessed by the cotransfection with their expression vectors with reporters; 5-deletion constructs of rat ICAM-1 promoter or 8xGAS-luc constructs, into FRTL-5 thyroid cells. RESULTS: The level of CBP RNA and protein were not changed by the treatment with TSH, IFN-y, forskolin and methimazole in FRTL-5, FRT and BRL liver cells. The CBP could be directly associated with STAT1. Furthernmore, the overexpression of CBP significantly increases the both promoter activities; rat ICAM-1 gene promoter which has GAS element and 8xGAS-luc cassette constructs. However the cotransfection of CI1TA decreased the constitutive and CBP-mediated transactivation of rat ICAM-1 promoter and SxGAS-luc cassette constructs. CONCLUSION: We identified that the two transcriptional coactivators; CBP and CIITA has differential roles in the regulation of transcriptional activity of GAS drived promoter. CBP increases the GAS activity through the direct binding with STATl, but CIITA inhibited the CBP-mediated transactivation of GAS activity.
Subject(s)
Animals , Rats , Colforsin , Intercellular Adhesion Molecule-1 , Interferon-gamma , Liver , Methimazole , RNA , Thyroid Gland , Thyrotropin , Transcriptional Activation , TransducersABSTRACT
The Changes of soluble Fas levels in Patients with Autoimmune Thyroid Diseases BACKGROUD: Apoptosis was observed in thyroid tissue from Hashimoto disease but not those from Graves disease. Recently Fas and Fas ligand interactions among thyrocytes were suggested to development of clinical hypothyroidism in Hashimoto disease.Soluble Fas produced as the form lacking the tranmembrane domain due to alternative splicing, is supposed to inhibit Fas-Fas ligand interaction and blocks Fas mediated apoptosis. METHODS: In tbis study, we measured serum soluble Fas to determine the possible involvement of this molecule in the autoimmune thyroid disease by enzyme linked immunosorbant assay in 29 patients with Graves disease, 30 patients with Hashimotos disease and 19 normal controls. RESULTS: Compared with normal subjeets (4.26 +/- 1.00 U/mL), soluble Fas was not increased in patients with Graves disease (4.23 +/- 1.14 U/mL, p>0.05) but it was increased in throtoxic Graves patients (4.70 +/- 1.26 U/mL, p<0.05) compared to euthyroid Graves (3.72 +/- 0.73 U/mL, p<0.05) and normal subjects (4.26 +/- 1.00 U/mL, p<0.05). The euthyroid and hypothyroid patients with Hashimoto disease showed low soluble Fas levels, 2.94 +/- 0.54 U/mL and 2.74 U/mL, respectively compare to the patients with Graves disease and normal subjects. The thyroid hormone levels to (T3 T4 and free T4) showed positive correlation with the serum titers of antithyroid autoantibodies, antithyroglobuin antibodies, antiperoxidase antibodies and thyrotropin binding inhibitor immunoglobulins. CONCLUSION: We found that the patients with thyrotoxic Graves disease had increased level of serum soluble Fas and the patients with Hashimoto disease showed low levels of soluble Fas compared to normal controls. Increased soluble Fas in Graves disease suggests increased expression of alternatively spliced Fas mRNA variant and decreased soluble Fas in Hashimoto disease suggests decreased Fas mRNA variant and increased full length membrane Fas, so these findings are related to the promotion of apoptosis of thyroid cells during autoimmune reaction in Hashimotos disease.
Subject(s)
Humans , Alternative Splicing , Antibodies , Apoptosis , Autoantibodies , Fas Ligand Protein , Graves Disease , Hashimoto Disease , Hypothyroidism , Immunoglobulins , Membranes , RNA, Messenger , Thyroid Diseases , Thyroid Gland , ThyrotropinABSTRACT
BACKGROUND: Leptin, the product of ob gene, is an important circulating hormone for the regulation of homeostasis of body weight and enegy expenditure. There was a previous reports that thyroid hormone is one of regulating factors of leptin gene expression in vitro. The aim of this study was designed to evaluate the role of thyroid hormone levels in the regulation of circulating leptin concentrations in human. METHODS: A total 16S subjects were studied; 76 patients with Graves disease, 49 patients with Hashimoto disease and 43 control sujjects. The correlation between thryoid hormone and leptin levels were analyzed and serum leptin levels were compared among the groups which was classified by thyroid functional status. Serum leptin concentratios were measured by radioimmunoassay. RESULTS: There were no significant differences in serum leptin levels between the groups of control, Graves disease and Hashimoto disease. The hypothyroid groups of Graves disease which was induced by excessive antithyroid drug treatment showed significant low levels(5.6 +/-2.8 ng/mL) compared to control(9.6 +/- 5.2 ng/ml) and thyrotoxic groups(10.0 +/- 5,0 ng/mL) CONCLUSION: The hypothyroid patients showed low levels of serum leptin concentrations it may indicate that thyroid horrnone play a role in the appropriate secretion of leptin in human.