Figure 5: NDP triggers FZD4 endocytosis by promoting FZD4 ubiquitination. | Nature Communications

Figure 5: NDP triggers FZD4 endocytosis by promoting FZD4 ubiquitination.

From: Norrin-induced Frizzled4 endocytosis and endo-lysosomal trafficking control retinal angiogenesis and barrier function

Figure 5

(a) Norrin-induced FZD4 internalization in HeLa cells. Norin internalization mediated by FZD4 K12R and FZD4 K13R is strongly reduced or absent. Scale bar, 10 μm. (b) Quantification of internalized Norrin, mean+s.d., n=18, ***P<0.001. (c) Intact HeLa cells expressing HA-ubiquitin were incubated with V5 antibody on ice to label cell surface FZD4. At the same time, cells were also incubated with FLAG-AP-NDP conditioned medium or control medium as indicated and subsequently subjected to 20 min internalization at 37 °C. After lysis, cell surface FZD4 was isolated using Protein A/G beads. Wild type FZD4 in the presence of Norrin is ubiquitinated, whereas FZD4 K12R and FZD4 K13R are not ubiquitinated. Note that cell surface bound NDP is below the detection limit in the diluted lysate (input), but can be detected after enrichment in the FZD4 immunoprecipitations.

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