Overexpression of USF Increases TGF-beta1 Protein Levels, But G1 Phase Arrest was not Induced in FRTL-5 Cells.
10.3346/jkms.2008.23.5.870
- Author:
Keun Sook KIM
1
;
Hye Seung JUNG
;
Yun Jae CHUNG
;
Tae Sik JUNG
;
Hye Won JANG
;
Myung Shik LEE
;
Kwang Won KIM
;
Jae Hoon CHUNG
Author Information
1. Division of Endocrinology and Metabolism, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea. jhchung@smc.samsung.co.kr
- Publication Type:Original Article ; Research Support, Non-U.S. Gov't
- Keywords:
Upstream Stimulatory Factor;
Transforming Growth Factor beta1;
FRTL-5 Cells
- MeSH:
Animals;
*Apoptosis;
Binding Sites;
Cell Cycle;
Cell Line;
G1 Phase;
*Gene Expression Regulation;
Promoter Regions, Genetic;
Protein Biosynthesis;
Rats;
Thymidine/chemistry;
Transfection;
Transforming Growth Factor beta1/metabolism;
Upstream Stimulatory Factors/*metabolism
- From:Journal of Korean Medical Science
2008;23(5):870-876
- CountryRepublic of Korea
- Language:English
-
Abstract:
Transforming growth factor-beta1 (TGF-beta1) is a potent inhibitor of cellular growth and proliferation by G1 phase arrest or apoptosis. We investigated the association of TGF-beta1 with the anti-proliferative effect of upstream stimulatory factor (USF) in Fischer rat thyroid cell line (FRTL-5) cells. [Methyl-(3)H] thymidine uptake was measured after treatment of FRTL-5 cells with TGF-beta1 to identify its anti-proliferative effect. USF-1 and USF-2 proteins were in vitro translated, and an electrophoretic mobility shift assay was performed to identify the interaction between USF and the TGF-beta1 promoter. FRTL-5 cells were transfected with USF cDNA, and then the expression of TGF-beta1 was examined with Northern and Western blotting. The cell cycle-regulating proteins associated with TGF-beta1 were also measured. TGF-beta1 significantly inhibited [methyl-(3)H] thymidine uptake in FRTL-5 cells. Two specific binding sites for USF were found in the TGF-beta1 promoter: -1,846~-1,841 (CACATG) and -621~-616 (CATGTG). Overexpression of USF increased both the mRNA levels and protein levels of TGF-beta1. However, the expression of cyclin D1, CDK4, cyclin E, and CDK2, and the phosphorylation of retinoblastoma protein remained unchanged. Overexpression of USF in FRTL-5 cells increased the expression of TGF-beta10 through specific binding to TGF-beta1 promoter. However, the USF-induced expression of TGF-beta1 did not cause G1 arrest.
