TY - JOUR
T1 - The RL-ET-14 cell line mediates expression of glutamine synthetase through the upstream enhancer/promoter region
AU - de Kruithof Julio, M.
AU - Labruyere, W.T.
AU - Ruijter, J.M.
AU - Vermeulen, J.L.
AU - Stanulovic, V.
AU - Stallen, J.M.
AU - Baldysiak-Fiegel, A.
AU - Gebhardt, R.
AU - Lamers, W.H.
AU - Hakvoort, T.B.M.
PY - 2005/1/1
Y1 - 2005/1/1
N2 - BACKGROUND/AIMS: The expression of glutamine synthetase (GS) in the mammalian liver is confined to the hepatocytes surrounding the central vein and can be induced in cultures of periportal hepatocytes by co-cultivation with the rat-liver epithelial cell line RL-ET-14. We exploited these observations to identify the regulatory regions of the GS gene and the responsible signal-transduction pathway that mediates this effect. METHODS: Fetal hepatocytes of wild-type or GS-transgenic mice were co-cultured with RL-ET-14 cells to induce GS expression. Small-interfering RNA was employed to silence beta-catenin expression in the fetal hepatocytes prior to co-culture. RESULTS: Co-cultivation of RL-ET-14 cells with fetal mouse hepatocytes induced GS expression 4.2-fold. The expression of another pericentral enzyme, ornithine aminotransferase and a periportal enzyme, carbamoylphosphate synthetase, were not affected. Co-culture of RL-ET-14 cells with transgenic fetal mouse hepatocytes demonstrated that GS expression was induced via its upstream enhancer located at -2.5 kb and that the signal mediator required a functional beta-catenin pathway. CONCLUSIONS: The 'RL-ET-14' factor specifically induces GS expression, working via its upstream enhancer in a beta-catenin-dependent fashion.
AB - BACKGROUND/AIMS: The expression of glutamine synthetase (GS) in the mammalian liver is confined to the hepatocytes surrounding the central vein and can be induced in cultures of periportal hepatocytes by co-cultivation with the rat-liver epithelial cell line RL-ET-14. We exploited these observations to identify the regulatory regions of the GS gene and the responsible signal-transduction pathway that mediates this effect. METHODS: Fetal hepatocytes of wild-type or GS-transgenic mice were co-cultured with RL-ET-14 cells to induce GS expression. Small-interfering RNA was employed to silence beta-catenin expression in the fetal hepatocytes prior to co-culture. RESULTS: Co-cultivation of RL-ET-14 cells with fetal mouse hepatocytes induced GS expression 4.2-fold. The expression of another pericentral enzyme, ornithine aminotransferase and a periportal enzyme, carbamoylphosphate synthetase, were not affected. Co-culture of RL-ET-14 cells with transgenic fetal mouse hepatocytes demonstrated that GS expression was induced via its upstream enhancer located at -2.5 kb and that the signal mediator required a functional beta-catenin pathway. CONCLUSIONS: The 'RL-ET-14' factor specifically induces GS expression, working via its upstream enhancer in a beta-catenin-dependent fashion.
U2 - 10.1016/j.jhep.2005.01.036
DO - 10.1016/j.jhep.2005.01.036
M3 - Article
C2 - 15876469
SN - 0168-8278
VL - 43
SP - 126
EP - 131
JO - Journal of Hepatology
JF - Journal of Hepatology
IS - 1
ER -