Figure 1.

TDP-43 promotes tau exon 10 inclusion. A, graphic representation of tau mini-gene SI9-LI10. B, TDP-43 was overexpressed or knocked down with siTDP-43 in tau mini-gene (pCI/SI9-LI10)-transfected N2a cells. The splicing products of tau exon 10 were determined by RT-PCR 48 h after transfection, and the level of tau exon 10 inclusion/exclusion was calculated. The expression of TDP-43 was detected by Western blotting. Alteration of TDP-43 affected the alternative splicing of tau exon 10. C, various amounts of pCI/TDP-43·HA were co-transfected with pCI/SI9-LI10 into HEK-293FT cells for 48 h. The alternative splicing products of tau exon 10 were analyzed by RT-PCR. The expression of TDP-43 tagged with HA was detected by Western blotting. The ratio of inclusion/exclusion of tau exon 10 was plotted against the amount of pCI/TDP-43. TDP-43 was found to enhance tau exon 10 inclusion dose-dependently. D, SH-SY5Y, N2a, HepG2, COS7, HEK-293FT, and HeLa cells were co-transfected with pCI/SI9-LI10 and pCI/TDP-43·HA for 48 h. The splicing products of tau exon 10 were determined, and the ratio of tau exon 10 inclusion and exclusion was calculated. TDP-43 was found to promote tau exon 10 inclusion independently of cell types. E and F, primary cortical neurons were co-transfected with pCI/TDP-43 and pCI/SI9-LI10 (E) or transfected with pCI/TDP-43 (F) for 48 h. The splicing products of exogenous (E) and endogenous (F) tau exon 10 were determined by RT-PCR. TDP-43 was found to promote tau exon 10 inclusion in primary cortical neurons. Data are presented as mean ± S.D. (error bars). *, p < 0.05; **, p < 0.01; #, p < 0.05; *, versus control; #, versus TDP-43. Con, control.