FIGURE 7.

Depletion of LH3 decreases MMP-9 cell surface recruitment as does the recombinant FN domain, which displaces MMP-9 from the fibroblast membrane. A, LH3 down-regulation in MRC-5 decreases MMP-9 cell surface recruitment. Equal amounts of cell lysates (CL) from control (ctl) and LH3-depleted (KD) MRC-5 incubated with v5-tagged MMP-9 (SN) were loaded onto gels. Recruitment was quantified by densitometry. A representative anti-v5 antibody immunoblot of equal amounts of MRC-5 cell lysates from three independent experiments (lower panel) and the corresponding anti-LH3 antibody immunoblot are shown. B, PLA analysis of WT or LH3-depleted HSF treated with v5-tagged MMP-9. The histogram shows interaction between v5-tagged MMP-9 and endogenous LH3 that is decreased when LH3 is depleted. Lower panels show immunofluorescence images of MMP-9 recruitment (green) to membranes of HSF with an overlap between MMP-9 and LH3 (yellow) that is decreased by LH3 depletion. C, the FN domain prevents MMP-9/LH3 interaction in a dose-dependent manner. PLA analysis of MRC-5 cells treated with MMP-9 only, FN only, or MMP-9 with increased concentrations of the FN domain (1:1, 1:2, and 1:10 corresponding to 1:3.4, 1:6.8, and 1:34 molar ratios). The histogram shows interaction between MMP-9 and endogenous LH3 that decreases as the concentration of FN increases. nb, number. Results represent mean values ±S.E. (error bars). *, p ≤ 0.05; **, p ≤ 0.01; ***, p ≤ 0.001.