Endocrinology and Metabolism

Case Report

Autoimmune Thyroiditis during Antiviral Therapy with Peginterferon.: Jung Min Roh, Jeong Seon Yoo, Yoon Bum Lee, Hye Rim An, Hong Kyu Choi, Kyo Tae Jung, Jong Suk Park, Kwan Sik Lee, Kyung Rae Kim; J Korean Endocr Soc. 2010;25(1):68-71. Published online March 1, 2010; DOI: https://doi.org/10.3803/jkes.2010.25.1.68

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Abstract PDF: Combination treatment with pegylated interferon and ribavirin has been established as a standard therapy for chronic hepatitis C. Although interferon therapy is relatively safe, an important side effect is the induction of autoantibodies and autoimmune disease, especially autoimmune thyroid disease. Interferon associated autoimmune thyroid disease can consist of autoimmune hypothyroidism, Graves' disease, and destructive thyroiditis. Thyroid disease may lead to dose reduction or discontinuation of therapy.

Original Articles

Differential Roles of Transcriptional Coactivators: CBP and CIITA on GAS (Interferon-r Activated Site) - Mediated Transcription in Thyroid Cells.: Eun Shin Park, Ho Kim, Soon Hee You, Soo Jung Park, Hyun Jin Kim, Soo Heung Chae, Do Hee Kim, Hee Jeong Han, O Yu Kwon, Young Kun Kim, Minbo Shong, Heung Kyu Ro; J Korean Endocr Soc. 1999;14(3):493-504. Published online January 1, 2001

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Abstract PDF: 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.

Thyrotropin Suppresses INF-r Mediated Gene Expression by Inhibiting Signal Transducer and Activation of Transcription 1(STAT1) Activity in FRTL-5 Cells.: Min Ho Song, Young Kun Kim, Heung Kyu Ro, Eun Shin Park, Soon Hee Yoo, Ho Kim, Kang Wook Lee, Hee Jung Han, Won Chan Joo, Jin Ho Won, Kyu Lim, Oh Yoo Kwon; J Korean Endocr Soc. 1998;13(4):536-553. Published online January 1, 2001

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Abstract PDF: BACKGROUND
The proinflammatory cytokine, IFN-y has been shown to exert pleiotropic effects in a variety of pathophysiologic conditions in autoimmune thyroid disease. The thyrocyte response to IFN-y is mediated two distinct classes of proteins, Janus kinases(Jakl and Jak2) and Signal Transducers and Activation of Transcription(STATl). The activation of STAT 1 is involved in the regulation of many interferon stimulated genes, such as MHC class II, intercellular adhesion molecules-1(ICAM-1) and MHC class II transactivator(CIITA) after the binding to the GASgFN- pactivated site) of the gene promoters. Recently we found TSH/forskolin inhibits IFN-y stimulated maximal expression of ICAM-1 in FRTL-5 cell. IFN-y action is localized between -175 bp and -97 bp from the start of translation of ICAM-1 gene which contains regulatory elements known to be involved in IFN-y action in other eukaryotic cells, palindromic IFN-y activated site(GAS)(5-TTTCCGGGAAA-3) which could bind STAT1, STAT3, STAT5, STAT6. Furthermore, the addition of TSH and forskolin causes a decrease in ICAM-1 promoter activity and its action was localized in GAS. These findings suggested TSH/cAMP signaling pathways downregulate IFN-y activated Janus kinase-STAT signaling path. We wanted to explore the possible involvement of elevated cAMP in the negative regulation of IFN-y induced STAT1 activation in thyroid cells. METHOD: We made several 5-deletion constructs of rat ICAM-1 promoter and analyzed the promoter activities by measuring the luciferase activity after tranfection into FRTL-5 cells. The protein/DNA complex was measured by electrophoretic mobility shift analysis using labeled oligonucleotide. We checked the level of total and phosphorylated STATl protein by immunoblot analysis using specific antibodies. RESULTS: Stimulation of IFN-y in FRTL-5 cells resulted in rapid activation of STATl/DNA binding activity, which was apparent after several minute of stimulation, maintains its activity until 48 h. Incubation of cells with TSH result in suppression of IFN-p mediated STAT1/DNA binding activity throughout the time course of activation by IFN-y. Addition of TSH into 5H maintained FRTL-5 cells did not change the total amount of latent STAT1 amount and also not affect IFN-y mediated production of total STAT1 until 4 h. IFN-y(100 U/mL) rapidly induced phosphorylation of STAT1 within 30 min. and maintained its level without significant change until 48 hours. Cells treated with TSH dramatically lowered the level of IFN-y induced production and phosphorylation of STAT1 after 12 h, 24 h, 36 h, and 48 h but TSH had no effect on the level of phosphorylated STATl within 4 h after IFN-y stimulation. The proteasome inhibitor, MG132 and phosphatase inhibitor, sodium orthovanadate did not block the TSH or forskolin mediated downregulation of phosphorylated STAT1. CONCLUSION: These results indicate a regulatory mechanism which TSH signaling can modulate the prolonged activation of Jak/Stat by IFN-y. We identified one of mechanisms related to TSH mediated negative suppression of the ICAM-1 gene; TSH/cAMP signaling pathways downregulate the cytokine activated Janus kinase-STAT signaling path.

Hormonal and Cytokine Regulation of ICAM-1 gene in FRTL-5 Thyroid Cells: Cloning and Analysis of 5-Regulatory Region of Rat ICAM-1 Gene.: Min Ho Song, Young Tae Shin, Young Kun Kim, Heung Kyu Ro; J Korean Endocr Soc. 1997;12(3):393-409. Published online January 1, 2001

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Abstract PDF: BACKGROUND
We have found abnormal expression of ICAM-1 in thyroid follicular cells from patients with Graves disease and Hashimoto disease. In this report, we present the hormonal regulation of ICAM-1 mRNA expression and the primary structure of 5-regulatory region which is important for transcriptional regulation of ICAM-1 gene. A I.S kb fragment of the 5-regulatory sequences are identified and linked to luciferase as a reporter. METHOD: Those reporter constructs were used to evaluate the expression in response to cytokines and hormones. Deletion analysis of 1.8 kb fragment of ICAM-1 promoter in FRTL-5 cells provide the evidence for the existence of several regulatory elements of enhancer and silencer in ICAM-1 gene transcription in thyroid cells. RESULTS: ICAM-1 mRNA is easily detected by Northern analysis using total RNA from FRTL-5 cells regardless of culture conditions. The transcripts of rat ICAM-1 showed single band of 2.6 kb in length. The FRT cells which was come from early FRTL cell culture did not show ICAM-1 mRNA with usual Northern analysis, We found differential regulation of ICAM-1 RNA level in different culture condition in FRTL-5 cells, The cells maintained at 3H (no hydrocortisone, no insulin, no TSH) condition showed the highest expression level compared to 4H, 5H, or 6H medium. Hydrocortisone markedly decreased the ICAM-1 RNA and insulin partially recovered the hydrocortisone induced repression. TSH which is important in growth and function of FRTL-5 cells could independently downregulate the ICAM-1 RNA levels. Forskolin (10 mM) could mimic the action of TSH on ICAM-1 mRNA. TNF-a and interferon-y increase ICAM-1 expression in FRTL-5 thyroid cells. TSH/forskolin inhibited maximal expression of ICAM-1 by TNF-a and interferon-r. Promoter activity of the ICAM-1 gene was positively regulated by cytokines, TNF-a and IFN-r and negatively regulated by thyroid stimulating hormone. The addition of TSH and FSK caused a 50% decrease in ICAM-1 promoter activity within 24 hour. The TSH and FSK action was mapped at 175 bp and 97 bp of the start of translation. The mutant construct pCAM-175 delGAS which has no GAS sequence showed no TSH mediated suppression of promoter activity. CONCLUSION: These findings suggested that hormones and cytokines differentially regulated the ICAM-1 gene expression and TSH downregulated ICAM-1 gene transcription by inhibiting the activation of IFN-r induced transcription factors which can bind the GAS of ICAM-1 promoter.

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