Figure 6

Nuclear localization of NF-κB inhibits terminal differentiation. (A) MyoD^-/- myoblasts were infected with empty capsid (pBABE) or virus expressing IκBα-SR (pBABE-IkB). Protein extracts from proliferating infected cells and uninfected cells (control) were analyzed by western blot analysis using an antibody specific to IκBα. (B) MyoD^-/- myoblasts were infected with empty capsid (pBABE) or virus expressing IκBα-SR (pBABE-IkB). Proliferating cells (GM), or cells induced to differentiate for 5 days, were fixed and assessed for myosin heavy chain (MyHC) expression (in green). Nuclei were visualized using DAPI (in blue). (C) Fusion index of myotubes from MyoD^-/- cells either infected with a control (pBABE) or an IκBα-SR (pBABE-IkB) expressing virus, n = 5, ** = P < 0.01, *** = P < 0.001. (D) MyoD^-/- myoblasts were infected with empty capsid (pBABE) or virus expressing IκBα-SR (pBABE-IkB). Protein extracts from a differentiation time course of infected and uninfected cells were analyzed by western blot analysis using the antibodies indicated