Stable expression and functional characterization of a Na+-taurocholate cotransporting green fluorescent protein in human hepatoblastoma HepG2 cells.
Sodium-dependent uptake of bile acids from blood is aliver-specific function which is mediated by theNa(+)-taurocholate cotransporting polypeptide(Ntcp). We report the stable expression of aNa(+)-taurocholate cotransporting green fluorescentfusion protein in the human hepatoblastoma cell lineHepG2, normally lacking Ntcp expression. Ntcp-EGFPassociated green fluorescence colocalized with Ntcpimmunofluorescence in the plasma membrane. Intransfected HepG2 cells, the fusion protein mediatedthe sodium-dependent uptake of the bile acidtaurocholate (K(m): 24.6 mumol/l) and of the anionicsteroids estrone-3-sulfate and dehydroepiandrosteronesulfate. We conclude that the Ntcp-EGFP fusion proteinfollows the sorting route of Ntcp, is functionallyidentical to Ntcp and could be used to monitor proteintrafficking in living HepG2 cells.
Kullak-Ublick
G A
GA
Divisions of Clinical Pharmacology/Toxicology, Department of Medicine, University Hospital, CH-8091, Zürich, Switzerland, kullak@kpt.unizh.ch.
Ismair
M G
MG
Kubitz
R
R
Schmitt
M
M
Häussinger
D
D
Stieger
B
B
Hagenbuch
B
B
Meier
P J
PJ
Beuers
U
U
Paumgartner
G
G