Figure 8.
DPP6 promotes cell adhesion and binds with ECM Fibronectin. Transfected COS7 cells were plated on 96-well dishes coated with poly-L-lysine (A–B) or coated with ECM proteins (Collagen IV, Fibronectin, Laminin or Collagen I, respectively) (C–D) for 1 h. Non-adherent cells were washed off and adherent cells were assayed by crystal violet staining. Expression of DPP6 significantly increased COS7 cell adhesion to the substratum poly-L-lysine compared to the control cells (p<0.001, unpaired Student’s t-test) (A–B). Graphs shows mean OD and standard error (n=4 experiments). COS7 cells expressing DPP6 showed significantly improved cell attachment to Fibronectin, but not to Collagen IV, Laminin or Collagen I, compared to the control cells (p<0.001, unpaired Student’s t-test) (C–D), Graphs shows mean OD and standard error (n=3 experiments). (E–F) Dendritic filopodia are enhanced by RGD peptides in DIV3 DPP6-GFP expressing hippocampal neurons. (E) DPP6-KO hippocampal neurons either expressed GFP (left) or DPP6-GFP (right). DIV3 neurons were treated with control RAD or RGD peptides (250 μM, 60min), fixed and visualized for actin filaments with TRITC-phalloidin (1:1000, Sigma). Arrowheads point out filopodia. (F) The density of filopodia in GFP expressing neurons with RDG treatment in DPP6-KO mice was slightly increased compared to control RAD treatment (n=28 for RAD, n=32 for RGD treatment, p>0.05, unpaired Student’s t-test), but in DPP6-KO neurons expressing DPP6-GFP, the density of filopodia is significantly increased with RGD treatment compared to the control (n=37 for RAD, n=38 for RGD treatment, p<0.05, unpaired Student’s t-test). Scale bar, 10 μm. Error bars represent the mean±SEM.