Fig. 2: LDs contact with endosomes and are engulfed in intermediate endosomes.

A, B A549 cells were transiently transfected with GFP-Rab5a and mc-Rab7a, and then treated with coumarin (10 μM) for 6 h (A) or AP1-C (10 μM) for the indicated time (B), followed by confocal imaging. Images were finally captured by the Zeiss 880 microscope with a 63x objective lens. The scale bar is 5 μm. Manders colocalization coefficients (MCC) were calculated by ImageJ (n = 10, 9, 8, and 8 for 0.5 h, 1 h, 3 h, and 6 h, respectively; compared to 0.5 h, for Rab7a/Rab5a, p = 0.1697, p = 0.0019, and p = 0.0002 for 1 h, 3 h, and 6 h, respectively; for AP1-C/Rab7a, p = 0.5240, p = 0.0151, and p = 0.0001 for 1 h, 3 h, and 6 h, respectively; for AP1-C/Rab5a, p = 0.1446 for 1 h, and p < 0.0001 for 3 h and 6 h). C A549 cells were transiently transfected with mc-Rab5a and GFP-Rab7a, then treated with AP1-C (10 μM) for the indicated times before being fixed by 4% PFA. Images were captured with the N-SIM with a 100x objective lens (n = 3 for each time point). The scale bar is 1 μm. The statistical significance of differences was determined by using the unpaired two-tailed student’s t test. The graphs represented data from three independent experiments, and data quantifications were expressed as mean ± s.e.m. *p < 0.05, **p < 0.01, ***p < 0.001; ns: no significance.