期刊名称:Proceedings of the National Academy of Sciences
印刷版ISSN:0027-8424
电子版ISSN:1091-6490
出版年度:2010
卷号:107
期号:13
页码:6082-6087
DOI:10.1073/pnas.0902661107
语种:English
出版社:The National Academy of Sciences of the United States of America
摘要:The cystic fibrosis transmembrane conductance regulator (CFTR) is expressed in many segments of the mammalian nephron, where it may interact with and modulate the activity of a variety of apical membrane proteins, including the renal outer medullary potassium (ROMK) K+ channel. However, the expression of CFTR in apical cell membranes or its function as a Cl- channel in native renal epithelia has not been demonstrated. Here, we establish that CFTR forms protein kinase A (PKA)-activated Cl- channels in the apical membrane of principal cells from the cortical collecting duct obtained from mice. These Cl- channels were observed in cell-attached apical patches of principal cells after stimulation by forskolin/3-isobutyl-1-methylxanthine. Quiescent Cl- channels were present in patches excised from untreated tubules because they could be activated after exposure to Mg-ATP and the catalytic subunit of PKA. The single-channel conductance, kinetics, and anion selectivity of these Cl- channels were the same as those of recombinant mouse CFTR channels expressed in Xenopus laevis oocytes. The CFTR-specific closed-channel blocker CFTRinh-172 abolished apical Cl- channel activity in excised patches. Moreover, apical Cl- channel activity was completely absent in principal cells from transgenic mice expressing the {Delta}F508 CFTR mutation but was present and unaltered in ROMK-null mice. We discuss the physiologic implications of open CFTR Cl- channels on salt handling by the collecting duct and on the functional CFTR-ROMK interactions in modulating the metabolic ATP-sensing of ROMK.