Fig. 6.

TBC1D2b/Rab22 axis regulates endocytosis of E-cadherin. a Immunoblot of E-cadherin in 344SQ and H1299 cells expressing TBC1D2b. Accumulation of a faster migrating band (~97 kDa) appears within ~4 h of TBC1D2b overexpression. Arrows designate different molecular weights of E-cadherin species. b Immunoblot of E-cadherin in 393P overexpressing human GFP-Rab22 over 24 h. E-cadherin (120 kDa) expression decreases upon Rab22 overexpression while a major degradation product (35 kDa) is observed and is dependent on Rab22 expression. c Treatment of 393P-GFP-Rab22 cell line with the lysosome inhibitor hydroxychloroquine (HCQ) or the proteasome inhibitor MG-132 at increasing concentrations for 24 h. d Upon TBC1D2b knockdown GFP-tagged E-cadherin co-localizes with RFP-LAMP1 lysosomes by live cell imaging in the 344SQ cell lines. Scale bars represent 10 µm. e E-cadherin internalization was assessed in the 344SQ-TBC1D2b and (f) 531LN2-TBC1D2b overexpressing cell lines through the biotin method. Quantification of western blot demonstrates that TBC1D2b suppresses E-cadherin internalization; all asterisks indicate statistical significance by t-test (*p ≤ 0.05)