ΔF508 CFTR Surface Stability Is Regulated by DAB2 and CHIP-Mediated Ubiquitination in Post-Endocytic Compartments
Fig 8
rΔF508 CFTR delivery to the late endosomes is inhibited in Dab2-depleted cells.
CFBE41o-ΔF cells were treated with control (A and B) or Dab2-specific (C) siRNA oligonucleotides. At 24 h after transfection, the cells were cultured at 27°C for an additional 48 h to facilitate cell surface delivery of ΔF508 CFTR. After the low-temperature rescue, one set of the control cells was transferred to 37°C for 1 h (A), another set of the control (B) and the Dab2-depleted cells (C) were treated with 5 mM ammonium chloride for 1 h at 37°C followed by immunofluorescent staining of CFTR and M6PR. (A) rΔF508 CFTR and mannose-6-phosphate receptor (M6PR) do not co-localize in control untreated cells. (B) Ammonium chloride treatment (inhibition of lysosomal degradation) resulted in rΔF508 CFTR and M6PR co-localization (right-hand panel, arrowheads). (C) Dab2 depletion and ammonium chloride treatment together enhanced rΔF508 CFTR staining; however, no co-localization of rΔF508 CFTR and M6PR is apparent.