TNS4-MET Interaction Attenuates MET Internalization and Lysosomal Targeting
(A) Endocytosis rate of biotinylated cell-surface MET in A549-TNS4_WT-GFP and control A549-GFP cells ± HGF (30 ng/ml) (mean ± SEM band intensity normalized to end point [20 min]; n = 3). Statistical differences at each time point between GFP- and TNS4_WT-GFP-overexpressing cells were analyzed by Student’s t test.
(B) FACS analysis of cell-surface MET endocytosis rate in A549-GFP, A549-TNS4_WT-GFP, or A549-TNS4_R474A-GFP cells ± HGF (30 ng/ml, 30 min) (mean ± SEM fluorescence intensity; n = 3).
(C) Total MET levels in control-, TNS4-, and GGA3-silenced A549 cells treated with DMSO or HGF (30 ng/ml, 1 hr) (mean ± SEM band intensity normalized to control-silenced cells; n = 3). Statistical significance was analyzed between control-silenced cells and the other conditions.
(D) Endocytosis rate of biotinylated cell-surface β1-integrin was measured as described in (A).
(E) MET and active β1-integrin coendocytosis upon HGF induction (30 ng/ml) in A549 cells labeled with cell-surface-bound MET (antibody directed against extracellular domain) and β1-integrin (12G10) antibodies. Scale bar, 10 μm.
(F) A549 cells cotransfected with TNS4 _WT-GFP or TNS4_R474A-GFP mutant and Lamp1-RFP were stained for MET (antibody directed against extracellular domain) after HGF (30 ng/ml) induction. r: Pearson’s correlation coefficient between Lamp1-RFP and MET staining in cells (mean ± SEM; n = 7 cells per condition). Scale bar, 10 μm. ∗p < 0.05, ∗∗p < 0.005, ∗∗∗p < 0.0005.