Fig. 3.

MMP-9 catalyzes CD73 shedding at the K547-F548 site. Selective MMP-9, MMP-2 inhibitors, and semi-selective MMP2/9 inhibitors were added to LPS/TNF-α-treated RPE cells, their effects on regulating membrane-expressed CD73 were analyzed by flow cytometry (a). Mutant and wild-type CD73 (b) were expressed in Cd73^−/− RPE cells (c), their responses to LPS/TNF-α treatment were tested (d). a Effects of selective MMP-2, MMP-9 inhibitors on protecting CD73 shedding (upper panel), and the dose-dependent effect of selective MMP-9 inhibitors (lower panel). b Coding sequence and amino acid residues at 547–548 sites in wild-type and mutant CD73. c Expression of Wt- and mutant-CD73 in Cd73^−/− RPE cells was verified by western blotting. d Responses of Wt- and mutant-CD73 to LPS/TNF-α treatment were tested by flow cytometry