Figure 6.
Tubby and Tulp1 function as bridging molecules to facilitate phagocytosis. (A) Excessive Tubby-N or Tulp1-N blocks RPE phagocytosis of POS vesicles. Fluorescence-labelled POS vesicles with endogenous tubby and Tulp1 were analysed for phagocytosis in ARPE19 cells in the presence or absence of excessive GST-Tubby-N, GST-Tulp1-N or GST control (4 μM), as described in Figure 1B. (B) Relative fluorescence intensity per cells in (A) was quantified in >100 cells per group (±s.e.m., n>100). (C) Excessive Tubby-N or Tulp1-N blocks macrophage phagocytosis of apoptotic Jurkat cells. Fluorescence-labelled apoptotic Jurkat cells were preincubated with GST-Tubby, GST-Tulp1 or GST, washed and analysed for phagocytosis in J774 macrophage cells in the presence or absence of excessive GST-Tubby-N, GST-Tulp1-N or GST, as described in (A). Confocal images of phagocytosed green fluorescence signals, DAPI signals and bright fields are superimposed. (D) Percentage of macrophages with phagocytosed Jurkat cells in (C) was quantified (±s.e.m., n>17, *P<0.001, apoptotic versus healthy in GST group, all others versus GST apoptotic). Bar=10 μm for all.