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A novel dephosphorylation‐activated conductance in a mouse renal collecting duct cell line
Author(s) -
Laycock S.,
Taylor H. C.,
Haigh C.,
Lee A. T.,
Cooper G. J.,
Ong A. C. M.,
Robson L.
Publication year - 2009
Publication title -
experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0958-0670
DOI - 10.1113/expphysiol.2009.047753
Subject(s) - autosomal dominant polycystic kidney disease , pkd1 , dephosphorylation , phosphatase , chemistry , polycystic kidney disease , microbiology and biotechnology , phosphorylation , kidney , cancer research , biology , biochemistry , endocrinology
Autosomal dominant polycystic kidney disease (ADPKD) is one of the most common inherited renal diseases. It is associated with the progressive development of renal tubular cysts, which may subsequently lead to renal failure. Studies into the genetic basis of ADPKD have identified two genes, PKD1 and PKD2 , that are mutated in ADPKD patients. The PKD1 and PKD 2 genes encode for two different proteins, TRPP1 and TRPP2. Previous studies have demonstrated the presence of both TRPP1 and TRPP2 in the renal collecting duct cell line M8. The aim of the following study was to investigate the functional properties of cation currents in these cells and to examine the effect of overexpression of TRPP1 using a transgenic cell model (M7). In M8 cells, initial whole cell currents were low. However, over time there was activation of a flow‐sensitive current, which was inhibited by gadolinium ( I Gd ). The I Gd was more selective for cations over anions, but did not discriminate between monovalent cations and was Ca 2+ permeable. Activation of I Gd was dependent on the presence of Ca 2+ and also required dephosphorylation. The protein phosphatase 2A inhibitor okadaic acid prevented activation of I Gd , suggesting that protein phosphatase 2A plays an important role in channel activation. The properties and magnitude of I Gd were unaffected in M7 cells, suggesting that overexpression of TRPP1 was without effect. I Gd was selectively inhibited by an antibody raised against the C‐terminus of TRPP2. However, its selectivity profile was different to TRPP2, suggesting that it is attributable to a TRPP2‐like channel or a TRPP2‐containing heteromeric channel. In conclusion, these data describe the functional identification of a novel dephosphorylation‐ and flow‐activated TRPP2‐related channel in mouse collecting duct cells.