Regulation of ENaC in mice lacking renal insulin receptors in the collecting duct. FASEB J 2013 Jul;27(7):2723-32
Date
04/06/2013Pubmed ID
23558339Pubmed Central ID
PMC3688749DOI
10.1096/fj.12-223792Scopus ID
2-s2.0-84878935313 (requires institutional sign-in at Scopus site) 36 CitationsAbstract
The epithelial sodium channel (ENaC) is one of the central effectors involved in regulation of salt and water homeostasis in the kidney. To study mechanisms of ENaC regulation, we generated knockout mice lacking the insulin receptor (InsR KO) specifically in the collecting duct principal cells. Single-channel analysis in freshly isolated split-open tubules demonstrated that the InsR-KO mice have significantly lower ENaC activity compared to their wild-type (C57BL/6J) littermates when animals were fed either normal or sodium-deficient diets. Immunohistochemical and Western blot assays demonstrated no significant changes in expression of ENaC subunits in InsR-KO mice compared to wild-type littermates. Insulin treatment caused greater ENaC activity in split-open tubules isolated from wild-type mice but did not have this effect in the InsR-KO mice. Thus, these results suggest that insulin increases ENaC activity via its own receptor affecting the channel open probability. To further determine the mechanism of the action of insulin on ENaC, we used mouse mpkCCDc14 principal cells. Insulin significantly augmented amiloride-sensitive transepithelial flux in these cells. Pretreatment of the mpkCCDc14 cells with phosphatidylinositol 3-kinase (LY294002; 10 μM) or mTOR (PP242; 100 nM) inhibitors precluded this effect. This study provides new information about the importance of insulin receptors expressed in collecting duct principal cells for ENaC activity.
Author List
Pavlov TS, Ilatovskaya DV, Levchenko V, Li L, Ecelbarger CM, Staruschenko AMESH terms used to index this publication - Major topics in bold
AnimalsBlotting, Western
Cells, Cultured
Chromones
Epithelial Sodium Channels
Hypoglycemic Agents
Immunohistochemistry
Indoles
Insulin
Ion Transport
Kidney
Kidney Tubules, Collecting
Membrane Potentials
Mice
Mice, Inbred C57BL
Mice, Knockout
Morpholines
Phosphatidylinositol 3-Kinases
Protein Subunits
Purines
Receptor, Insulin
Signal Transduction
Sodium
TOR Serine-Threonine Kinases
