Open AccessA Regulatory Role of Polycystin-1 on Cystic Fibrosis Transmembrane Conductance Regulator Plasma Membrane Expression
Author(s) -
Masahiro Ikeda,
Peter Fong,
Jie Cheng,
Alessandra Boletta,
Feng Qian,
Xue Mei Zhang,
Hui Cai,
Gregory G. Germino,
William B. Guggino
Publication year - 2006
Publication title -
cellular physiology and biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.486
H-Index - 87
eISSN - 1421-9778
pISSN - 1015-8987
DOI - 10.1159/000095133
Subject(s) - cystic fibrosis transmembrane conductance regulator , autosomal dominant polycystic kidney disease , transfection , secretion , cystic fibrosis , microbiology and biotechnology , regulator , pkd1 , chemistry , polycystic kidney disease , biology , cell , medicine , endocrinology , cell culture , kidney , gene , biochemistry , genetics
Autosomal dominant polycystic kidney disease (ADPKD) is caused by genetic mutations in either PKD1 or PKD2, the genes that encode polycystin-1 (PC-1) and polycystin-2 (PC-2), respectively. ADPKD is characterized by the formation of multiple, progressive, fluid-filled renal cysts. To elucidate the mechanism of fluid secretion by ADPKD cysts, we examined the effect of PC-1 on the plasma membrane expression of cystic fibrosis transmembrane conductance regulator (CFTR), a key Cl(-) secretory protein. Five stably transfected MDCK lines were used in this study: two transfected with empty vector (control cells) and three expressing human PC-1 (PC-1 cells). The cAMP-induced endogenous short circuit currents (I(sc)) were smaller in PC-1 cells than in control cells. Compared to control cells, PC-1 cells transiently expressing pEGFP-CFTR showed significant reduction of whole cell cAMP-activated Cl(-) currents. Cell surface biotinylation experiments also indicated a reduction in surface expression of CFTR in PC-1 cells compared to control. Furthermore, studies using CHO cells transiently expressing PC-1 and CFTR suggest the importance of the PC-1 COOH-terminus in the observed reduction of CFTR plasma membrane expression. No differences in either endogeneous K(+) currents or P2Y receptor responses were observed between PC-1 and control cells, indicating the specificity of PC-1's action. These results indicate that PC-1 selectively maintains low cell surface expression of CFTR. Moreover, these findings suggest that the malfunction of PC-1 enhances plasma membrane expression of CFTR, thus causing abnormal Cl(-)secretion into the cyst lumen.