Figure 3. ADAM13 function is dispensable for CNC migration in vitro.
(A) ADAM13 and 19 knock down has no effect on CNC migration in vitro. Embryos were injected in one cell at the two-cell stage with a mixture of GFP mRNA and either control morpholino (Ctl), ADAM13 morpholino (MO13) or ADAM13 and 19 morpholino (2MO). At stage 15, embryos were sorted and CNC explants placed on fibronectin-coated 96-well plates. For each case, pictures of typical explants are shown before migration (t=0), at the end of the sheet migration phase (t=6h) and at the end of the single cell migration phase (t=16h). Morphant CNC cells were capable of migrating in vitro in a pattern indistinguishable form the control CNC. (B) ADAM13 knock down in CNC is efficient and prevents Cadherin-11 cleavage. Twenty CNC were dissected at stage 15 and placed on FN substrate for 2 hours before cell surface proteins were biotinylated. Proteins were extracted and immunoprecipitated sequentially using a goat anti-ADAM13 antibody (gA13), the mouse mAb to Cadherin-11 (1B4) and the mouse mAb to integrin 1 (8C8). Both gA13 and 1B4 recognize the cytodomains of ADAM13 and Cadherin-11, respectively. ADAM13 knock down completely abolishes the expression mature ADAM13 at the cell surface (ADAM13, arrowhead). The full length Cadherin-11 protein is still strongly expressed (Cad-11, arrowhead a) but is no longer cleaved (Cad-11, arrowhead b). Integrin α5β1 cell-surface expression is unaffected by ADAM13 knockdown.
