Fig. 4

UBE2O controls the secretion of exosome-related PTRF and inhibits exosome secretion. A UBE2O was transiently transfected into PTRF or SDPR stable HeLa cell line with PEI. Transmission electron microscopy images of exosomes derived from overexpression HeLa cells were shown as indicated. Scale bar: 100 nm. B Exosomes from four groups of overexpressed cells were diluted in the same fold (1:1000). Then, the size distribution of exosomes was identified with nanoparticle tracking analysis (NTA). C, D HeLa cells were stably transfected with Flag-PTRF and transiently transfected with UBE2O-Myc. After 40 h of cell culture, exosomes in the cell supernatants were extracted. Exosome components and overexpressed cell components were analyzed by western blot. E, F, G, H Histograms showed densitometry analyses of exosomal PTRF (E), cell PTRF (F), CD63 (G) and TSG101 (H) expression relative to cell GAPDH expression. I Total protein of exosomes from four groups of overexpressed cells was measured by BCA assay. J The number of particles which with the size in 30–150 nm was determined by NTA. All statistical data are the means \(\pm\) SEM from more than 3 independent experiments. *P \(<\) 0.05; **P \(<\) 0.01; ***P \(<\) 0.001