The Cystic Fibrosis Transmembrane Conductance RegulatorI s a Dual ATP and Chloride Channel”

IGNACIO L. REISIN, ADRIANA G. PRAT, EDWARD H. ABRAHAM, JANE F. AMARAN, RICHARD J. GREGORYN, DENNIS A. AUSIELLO AND HORACIO F. CANTIELLO

JOURNAL OF BIOLOGICAL CHEMISTRY

Año: 1994 p. 20584 - 20591

0021-9258

The cysticf ibrosis transmembrane conductance regulator (CFTR) belongsto a superfamily of proteins implicated in the transporot f ions, proteins, and hydrophobic substances. Recent studies have demonstrated that CFTR is a protein kinase A-sensitive anion channel regulated by ATP. In the present study, patch-clamp techniques were used to assess the role of CFTR in the transport of C1- and ATP. The stable transfection of mouse mammary carcinoma cells, C127i, with the cDNA for human CFTR resulted in the appearance of a diphenylamine- 2-carboxylate-inhibitable C1- channel, which was activated by CAMP under whole-cell and cell-attached conditions and by protein kinase A plus ATP under excised, inside-out conditions. CFTR expression was also associated with the electrodiffusional movement of ATP as indicated by the CAMP activation of ATP currents measured under whole-cell conditionsI. n excised, inside-out patches, it was demonstrated that ATP currents were mediated by ATP-conductive channels, which were also activated by protein kinase A and blocked by the C1- channel blocker diphenylamine-2- carboxylate under excised, inside-out conditions. Single-channel currents observed in the presence of asymmetrical Cl-/ATP concentrations indicated that the same conductive pathway was responsible for both ATP and C1- movement. Thus, CFTRi s a multifunctional protein with more than one anion transport capability and may modify signal transduction pathways for C1- or other secretory processes by the selective delivery of nucleotides to the extracellular domain.also associated with the electrodiffusional movement of ATP as indicated by the CAMP activation of ATP currents measured under whole-cell conditionsI. n excised, inside-out patches, it was demonstrated that ATP currents were mediated by ATP-conductive channels, which were also activated by protein kinase A and blocked by the C1- channel blocker diphenylamine-2- carboxylate under excised, inside-out conditions. Single-channel currents observed in the presence of asymmetrical Cl-/ATP concentrations indicated that the same conductive pathway was responsible for both ATP and C1- movement. Thus, CFTRi s a multifunctional protein with more than one anion transport capability and may modify signal transduction pathways for C1- or other secretory processes by the selective delivery of nucleotides to the extracellular domain.