Fox alternative RRM exon splicing in adult mouse. (A) The inclusion/skipping of Fox-1 exon 11, Fox-2 exon 6, and Fox-3 exon 8 in adult cerebellum, cortex, striatum, heart, and muscle was studied by RT-PCR. The bands marked by an asterisk represent incompletely denatured PCR product. Fox-2 exon 6 skipping is induced in differentiating C2C12. (B) Mouse myoblastoma C2C12 were stimulated to form myotubes in medium containing 2% horse serum. Cells were harvested 0, 2, 4, and 6 d after starting the differentiation. The splicing of Fox-2 exon 6 was studied by RT-PCR. Analysis of the muscle Fox proteins by Western blotting. (C) Protein lysate from purified mouse skeletal muscle nuclei were probed by antibodies specifically recognizing all Fox proteins with an intact RRM (lane αFoxRRM; see also Fig. 5B), Fox-1-specific antibody (lane αFox-1), and anti-Fox-2 antibody (lane αFox-2). The Fox-2ΔE6 isoforms (right) are detected only by the anti-Fox-2, but not by the anti-RRM or the anti-Fox-1 antibodies.
