P < 0.05 as calculated by the Mann-Whitney's test; *, statistically not significant difference in HCV infectivity compared to infectivity in absence of drugs. Altogether, our data confirm the role of cholesterol in HCV entry and bring to light a similar response of Huh-7w7/mCD81 and Huh-7 cells to cholesterol depletion and replenishment in terms of HCV infection. We next analyzed by flow cytometry the surface expression of CD81 and its association with TEMs in Huh-7w7/mCD81 cells treated with MβCD or MβCD-cholesterol Selleck ABT-737 complexes (Figure

6), and expression of CD151 was used as a control (right panels). MβCD treatment of Huh-7w7/mCD81 cells reduced MT81 labelling MNK inhibitor by 58 ± 7% (Figure 6Aa), suggesting that cholesterol depletion induced a decrease in total cell surface expression of mCD81 in Huh-7w7/mCD81 cells. Even with cholesterol replenishment, CD81 expression level could not be restored to conditions that would enable HCV infectivity (Figure 6Ac, MβCD+Chol). Incubation of MβCD-treated

cells with increasing concentrations of preformed MβCD-cholesterol complexes raised cell surface mCD81 expression level (Figure 6B). However, a concentration four times higher than needed to reverse the inhibitory effect of MβCD on HCV infectivity (10 mM instead of 2,5 mM) was necessary to reach www.selleckchem.com/products/sc79.html the cell surface mCD81 expression level of untreated cells. Interestingly, treatment with MβCD alone had no effect on TEM-associated mCD81 population in Huh-7w7/mCD81 cells, as determined using MT81w (Figure 6Ab). Conversely, cholesterol enrichment of non depleted cells with preformed MβCD-cholesterol complexes led to a 2 ± 0.6 fold increase of TEM-associated mCD81 population (Figure 6Af), without any change in the total CD81 population (Figure 6Ae). These results confirm the role of cholesterol in TEM organization. Expression of CD151 under different conditions was not affected (Figure 6A, right panels). Figure

6 Cholesterol depletion affects total CD81 Selleckchem Fludarabine cell surface expression. A, Flow cytometry analysis of CD81 and CD151 expression on the cell surface of Huh-7w7/mCD81 cells. Upper panels: cells were treated with 7.5 mM of MβCD (MβCD) or left untreated (NT). Middle panels: cells were treated with 7.5 mM of MβCD (MβCD) followed by 2.5 mM of MβCD-Cholesterol (MβCD + Chol). Lower panels: cells were treated with 2.5 mM of MβCD-Cholesterol (Chol) or left untreated (NT). B, Cells were treated with 7.5 mM of MβCD (MβCD) followed by increasing concentrations (in mM) of MβCD-Cholesterol (MβCD + Chol) and total cell surface CD81 expression compared to untreated cells (NT) was measured using MT81 mAb. Our results differ from those of Silvie et al. showing that similar MβCD treatment of Hepa1–6 cells did not lead to a significant decrease of total CD81 cell surface expression [23]. However, it has to be noted that the tetraspanin CD9, expressed in Hepa1–6 cells but not in Huh-7 cells, has been shown to increase stability of tetraspanin complexes [40].