4B). Therefore, Gal-1 promotes HepG2 cell adhesion through an integrin-mediated process involving PI3K and/or ERK1/2 signaling routes. To determine whether Gal-1 plays additional roles in liver physiology, we further determined its ability to modulate BC formation. When HepG2 cells, which represent a model of differentiated HCC cells for studying hepatocyte polarization, were cultured on coverslips, they acquired the polarized phenotype characterized by the appearance of BC between adjacent cells

in a time-dependent manner (Fig.5A,B). Notably, this effect was substantially enhanced after plating the cells for 24 hours in the presence of rGal-1 (7 μM). In fact, cell polarization significantly increased, GSK126 manufacturer reaching considerable click here levels after exposure to exogenous rGal-1 (15 ± 1 BC/100 cells versus control: 9 ± 1) for 48 hours. Moreover, maximal cell polarization was reached following exposure to rGal-1 for 72 hours, a time point that did not differ from control cell polarization. This effect also involved the carbohydrate recognition domain of Gal-1, because it was significantly prevented by pretreatment with 10 mM thiodigalactoside (TDG)

(Fig. 5C). However, when cells were cultured in the presence of rGal-3 (7 μM) for 48 hours, cell polarization was not significantly different with respect to controls, indicating that acceleration of cell polarization is a Gal-1–specific effect (Fig. 5C). To determine whether endogenous Gal-1 regulates the function of HCC cells, we assessed the

effects of Gal-1 overexpression this website on HepG2 cell polarization. Interestingly, HepG2-G2 cells showed an increase in cell polarization (153 ± 8%), which was considerably inhibited in the presence of TDG (Fig. 5C). These findings imply a novel unrecognized role for Gal-1 in accelerating HepG2 cell polarization and promoting BC development. To evaluate whether Gal-1–induced cell polarization is secondary to the observed effect on cell adhesion or, to the contrary, these are two separate effects, we first allowed cells adhere to coverslips for 4 hours. Then, we added exogenous rGal-1 or knocked down Gal-1 expression by way of siRNA-mediated silencing. After 48 hours, cell polarization was analyzed. When rGal-1 was added 4 hours after cell adhesion, no significant differences (120 ± 8%) were observed in cell polarization with respect to control cells (in the absence of rGal-1; 94 ± 15%) (Fig. 5D), suggesting that the presence of rGal-1 at the time of cell plating was necessary to promote cell polarization (156 ± 5%). On the other hand, siRNA-mediated Gal-1 silencing resulted in no significant differences in cell polarization (90 ± 5%) with respect to cells transfected with scrambled siRNA (104 ± 15%).