Cargando…

Overexpression of USF Increases TGF-β1 Protein Levels, But G1 Phase Arrest was not Induced in FRTL-5 Cells

Transforming growth factor-β1 (TGF-β1) is a potent inhibitor of cellular growth and proliferation by G1 phase arrest or apoptosis. We investigated the association of TGF-β1 with the anti-proliferative effect of upstream stimulatory factor (USF) in Fischer rat thyroid cell line (FRTL-5) cells. [Methy...

Descripción completa

Detalles Bibliográficos
Autores principales: Kim, Keun-Sook, Jung, Hye Seung, Chung, Yun Jae, Jung, Tae Sik, Jang, Hye Won, Lee, Myung-Shik, Kim, Kwang-Won, Chung, Jae Hoon
Formato: Texto
Lenguaje:English
Publicado: The Korean Academy of Medical Sciences 2008
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2580023/
https://www.ncbi.nlm.nih.gov/pubmed/18955796
http://dx.doi.org/10.3346/jkms.2008.23.5.870
Descripción
Sumario:Transforming growth factor-β1 (TGF-β1) is a potent inhibitor of cellular growth and proliferation by G1 phase arrest or apoptosis. We investigated the association of TGF-β1 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-β1 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-β1 promoter. FRTL-5 cells were transfected with USF cDNA, and then the expression of TGF-β1 was examined with Northern and Western blotting. The cell cycle-regulating proteins associated with TGF-β1 were also measured. TGF-β1 significantly inhibited [methyl-(3)H] thymidine uptake in FRTL-5 cells. Two specific binding sites for USF were found in the TGF-β1 promoter: -1,846~-1,841 (CACATG) and -621~-616 (CATGTG). Overexpression of USF increased both the mRNA levels and protein levels of TGF-β1. 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-β10 through specific binding to TGF-β1 promoter. However, the USF-induced expression of TGF-β1 did not cause G1 arrest.