Octamer factor expression in mouse epidermal Langerhans cells.

(A) Immunoblots with nuclear proteins from freshly explanted Langerhans cells (immature phenotype, day 0, lane 1), Langerhans cells cultured for 24 hours (intermediate phenotype, day 1, lane 2), and maturated Langerhans cells (mature phenotype, day 3, lane 3). (B) EMSAs with nuclear proteins from freshly explanted Langerhans cells (day 0, lane 1), Langerhans cells cultured for 24 hours (day 1, lane 2), and mature Langerhans cells cultured for 3 days (day 3, lane 3). As a control for specificity of DNA binding, an excess of unlabeled octamer probe was added to nuclear extract from mature Langerhans cells (C, lane 4). The octamer-specific complex is designated I (see below). The asterisk and the circle indicate prominent unspecific complexes. The signals of the free probe are cut off. (C) Supershift EMSAs performed with nuclear extracts from freshly explanted Langerhans cells (day 0, lanes 1-3), Langerhans cell cultured for 24 hours (day 1, lanes 4-6), and maturated Langerhans cells after 3 days in culture (day 3, lanes 7-9). For supershift EMSA, 1 μl of each of the octamer-factor–specific antibodies was added as indicated (lanes 2 + 3, 5 + 6, and 8 + 9). The detectable octamer-specific DNA complex is composed of Oct-1 (I).