Figure 4.

NTCP regulation through FXR and pPKC. (A) Protein western blots and (B) quantitated bands of NTCP, FXR, pAKT, pmTOR, pPKC and αSMA from LX2^NTCP+ sorted cells. OCA, an FXR agonist, was incubated with LX2^NTCP+ at concentrations of 0.05 and 1 µM, as described in the Materials and methods section. (C) Bands of western blot of FXR and αSMA and their (D) quantitations were performed. (E) Flow cytometry analysis of transmembrane and intracellular expression of NTCP in αSMA positive LX2 (αSMA⁺/NTCP⁺) (calculated intracellular NTCP=Total NTCP expressions – transmembrane NTCP). (F) HA-100, a pPKC inhibitor, was incubated with LX2^NTCP+ sorted cells at a concentration of 7 µM. Flow cytometry analysis was used to assess intensities of NTCP and αSMA. αSMA, alpha smooth muscle actin; FXR, farnesoid X receptor; MFI, mean fluorescence intensity; NTCP, sodium taurocholate cotransporting polypeptide; OCA, obeticholic acid; PKC, protein kinase C; TCA, taurocholic acid.