CELLULAR EXPRESSION OF CFTR IN CYSTIC-FIB ROSIS - DEFECTIVE CAMP-DEPENDENT REGULATION OF GLYCOCONJUGATE SECRETION IN CYSTIC-FIBROSIS TRACHEAL EPITHELIAL-CELLS TRANSFECTED WITH SV40 LARGE T-ONCOGENE

Epithelial tracheal cells isolated from two fetuses with cystic fibros is (CF) and non-CF fetuse (control) were transfected with a plasmid ve ctor recombined with the large T oncogene of SV40. All transfected cel ls expressed SV40 antigen and exhibited an epithelial morphology (junc tional complex, cytokeratins). CFT cells retained the mutations of the CF gene, one heterozygous for the S549N/N1303K substitutions (CFT-1 c ells), the other homozygous for the deletion DELTAF508 (CFT-2 cells). Accordingly, these CFT cells exhibited the defective beta-adrenergic r egulation of chloride conductance. We compared the responsiveness of c ontrol (NT-1 cells) and CF cells (CFT-1 and CFT-2 cells) to agonists o f the protein kinase A (PKA)-dependent pathway for stimulation of glyc oconjugate secretion. We show that the isoproterenol (10(-5) M) and fo rskolin (10(-5) M) markedly increased the cAMP content and the PKA act ivity of all three cell lines. In contrast, these effectors produced a n increase in glycoconjugate secretion in control cells, but not in CF T-1 and CFT-2 cells. In conclusion, our results indicate that CFT cell s do not respond to agonists of the PKA-dependent pathway for stimulat ion of both glycoconjugate secretion and chloride transport, which sug gests the involvement of CFTR in these two processes.