Role of CFTR in lysosome acidification

The role of CFTR in lysosome acidification was examined in CFPAC-1 pancreatic adenocarcinoma cells with the delta F508 mutation that were transduced with a retroviral vector (PLJ-CFPAC) or with the normal CFTR gene (CFTR-CFPAC). Steady-state lysosomal pHi in intact cells was lower in PLJ-CFPAC cells than CFTR-CFPAC cells (3.55 vs 3.80) and was not affected by cAMP or forskolin. Initial rates of ATP-dependent acidification of isolated lysosomes and steady-state ATP-dependent pHi were similar in both cell lines over a range of chloride concentrations and were not altered when cells were exposed to cAMP or to forskolin prior to preparation of lysosomes. These observations suggest that CFTR plays no role in acidification of lysosomes, possibly due to limited permeability of lysosomal membranes to chloride.