Figure 3. HIV tat and gp120 activate MAPK in polarized oral epithelial cells.

(A) Polarized cells were treated with active or inactive tat and gp120, alone or in combination. In parallel experiments, cells were exposed to UV-inactivated or active HIV-1_SF33. Culture medium was changed daily to add fresh proteins and virus, and at day 5 the TER was measured. (B) After measurement of TER, the same cells were used for evaluation of MAPK activation. Cells were extracted, and total and phosphorylated ERK1/2 were detected by Western blot assay. (C) Polarized cells were treated with active forms of tat or gp120 in the presence or absence of MAPK inhibitor U0126. Tat -and gp120 -untreated cells with or without U0126 served as controls. At day 5 TER of polarized cells was measured. (D) The same cells from panel C after measurement of TER were extracted and used for evaluation of phosphorylated and total ERK1/2. The mean densities of pixels in the protein bands were measured by Image J software, and the results for each gel are shown as a bar graph under each blot. A and C: Error bars indicate SEM (n = 3).