- Peroxiredoxin I and II are Involved in Hydrogen Peroxide Regulation in FRTL-5 Thyroid Cells.
-
Ho Kim, Tae Hoon Lee, Eun Shin Park, Jae Mi Suh, Soo Jung Park, Hyo Kyun Chung, Hyun Jin Kim, Soo Hong Chae, Do Hee Kim, O Yu Kwon, Young Kun Kim, Min Ho Shong, Heung Kyu Ro
-
J Korean Endocr Soc. 2000;15(1):55-69. Published online January 1, 2001
-
-
-
 Abstract
 PDF
- BACKGROUND
Peroxiredoxins (Prx) play an important role in regulating cellular differentiation and proliferation in several types of mammalian cells. One mechanism for this action involves modulation of hydrogen peroxide (H2O2)-mediated cellular responses. This report examines the expression of Prx I and Prx II in thyroid cells and their roles in eliminating H2O2 produced in response to TSH. METHODS: The expression of Prx-I and Prx-II were quantiated in FRTL-5 after stimulation with Thyroid stimulating hormone (TSH), Forskolin (FSK), Methimazole (MMI) and hydrogen peroxide (H2O2). Transient transfections were carried out with FRTL-5 cells at 80% confluency and 20microgram of pCRprx I and pCRprx II or equivalent molar amounts of the pCR3.1TM basic vector. Transient transfection used an electroporation technique. Intracellular H2O2 was assayed in FRTL-5 cells with a fluorescent dye, 2', 7'-dichlorofluoresceindiacetate (DCFH-DA). Apoptosis of cells were evaluated by using an detection kit (Promega, Inc., Madison, WI). RESULTS: Prx I and Prx II are constitutively expressed in FRTL-5 thyroid cells. Prx I expression, but not Prx II expression, is stimulated by exposure to TSH and H2O2. In addition, methimazole (MMI) induces a high level of Prx I mRNA and protein in these cells. Overexpression of Prx I and Prx II enhance the elimination of H2O2 produced by TSH in FRTL-5 cells. Treatment with 500microM H2O2 causes apoptosis in FRTL-5 cells as evidenced by standard assays of apoptosis (i.e., terminal deoxynucleotidyl transferase deoxyuridine triphosphate-biotin nick end-labeling (TUNEL), BAX expression and PARP cleavage. Overexpression of Prx I and Prx II reduces the amount of H2O2-induced apoptosis measured by these assays. CONCLUSION: These results suggest that Prx I and Prx II are involved in the removal of H2O2 in thyroid cells, and can protect these cells from undergoing apoptosis. These proteins are likely to be involved in the normal physiological response to TSH-induced production of H2O2 in thyroid cells.
- 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
-
-
-
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.
|
KES
