Figure 6. Combined knock-down of ADAM9, ADAM10, ADAM17 and MMP9 does not affect 5-HT_4d receptor-stimulated APP shedding.

(A) and (B) SH-SY5Y cells, co-transfected with pEAK12-AP-APP, pcDNA3.1-5-HT₄ and combinations of 3 nM siRNA for knock-down of ADAM9 (A9) and ADAM10 (A10), ADAM9 (A9) and ADAM17 (A17), ADAM10 (A10) and ADAM17 (A17) in (A) or ADAM9, 10 and 17 or ADAM9, 10, 17 and MMP9 in (B), were treated with 1 µM prucalopride (5-HT₄ receptor agonist) in the absence or presence of 80 µM GM6001 (metalloproteinases inhibitor) (B) and secretion of sAPPα was analyzed via measuring SEAP. (C) Cell lysates of experiments in (A) and (B) were analyzed for protein expression of ADAM9, 10, 17 and MMP9 by western blotting. ADAM10 and ADAM17 immature precursor proteins are indicated by an x, whereas the mature catalytically active forms are indicated by an xx for ADAM9, 17 and MMP9. The immature ADAM9 and the mature ADAM10 proteins were not visible. (D) Quantification of experiments in (C). Values shown are mean ± SEM of 6 individual wells and were normalized to vehicle control. ** P<0.01, *** P<0.001, one-way ANOVA with Tukey-Kramer's post-hoc test.