The TLR4 adaptor TRAM controls the phagocytosis of Gram-negative bacteria by interacting with the Rab11-family interacting protein 2
Fig 2
Super resolution microscopy of TRAM and TLR4 at the developing E. coli phagosome.
Primary human macrophages (Mϕ) stimulated with E. coli bioparticles (red) for 30 min and stained for F-actin (cyan) and TRAM or TLR4 (green) and imaged by 3-D STED. (A) Distribution of TRAM before and after internalization of E. coli. Upper and lower left panels show 3-D rendering of F-actin together with E. coli or TRAM. Mid and right panels show TRAM alone or TRAM together with E. coli. (B) Distribution of TLR4 before and after internalization of E. coli. Left panels show F-actin together with E. coli or TLR4. Right panels show E. coli together with TLR4 or TLR4 alone. (C) TLR4 levels on E. coli phagosomes in Mϕ treated with NS RNA or FIP2 siRNA and stimulated for 15 and 15+15 min. (D) TLR4 levels on E. coli phagosomes in Mϕ treated with NS RNA or TRAM siRNA and stimulated for 15 min and 15+15 min. n = number of cells monitored. One-way ANOVA Kruskal-Wallis test with adj. p values, **** (p < 0.0001) and ** (p = 0.001). Red bars: mean ± SD from one representative human donor of three. PM = plasma membrane. Scale bars = 1 μm or 5 μm.