Insulin increases the functional activity of the renal NaCl cotransporter

• Type of Material: Article
• Authors: Maria Chavez-Canales, Universidad Nacional Autónoma de México; Juan Pablo Arroyo, Universidad Nacional Autónoma de México; Benjamin Ko, University of Chicago; Norma Vazquez, Universidad Nacional Autónoma de México; Rocio Bautista, Instituto Nacional de Cardiología Ignacio Chávez; Maria Castaneda-Bueno, Universidad Nacional Autónoma de México; Norma A. Bobadilla, Universidad Nacional Autónoma de México; Robert S. Hoover Jr, Emory University; Gerardo Gamba, Universidad Nacional Autónoma de México
• Language: English
• Date: 2013-02-01
• Publisher: Lippincott, Williams & Wilkins
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: Lippincott Williams Wilkins.; © 2013 Wolters Kluwer Health
• Title of Journal or Parent Work: Journal of Hypertension
• ISSN: 0263-6352
• Volume: 31
• Issue: 2
• Start Page: 303
• End Page: 311
• Grant/Funding Information: Supported in part by the Leducq Foundation Transatlantic Network on Hypertension and CONACYT Grant 165815 (to G.G.); the NIH K08 DK081728 (to B.K.) and R01 DK-085097 (to R.S.H.); and the Research Service, Atlanta VA Medical Center (R.S.H.).; M.C-C was supported by a scholarship from CONACYT-Mexico; and is a graduate student in the Biomedical Science Ph.D. programs of the Universidad Nacional Autónoma de México.
• Keywords: hypertension; with no lysine kinase 3; Science & Technology; distal convoluted tubule; Peripheral Vascular Disease; Life Sciences & Biomedicine; BLOOD-PRESSURE; PHOSPHORYLATION; NEW-MODEL; Cardiovascular System & Cardiology; NCC; ANGIOTENSIN-II; thiazide; obesity; SODIUM; ENAC; IN-VIVO; salt transport; NA+-CL-COTRANSPORTER; EXPRESSION
• Research Categories: Biology, Physiology; Health Sciences, Medicine and Surgery; Biology, Molecular

Abstract

Objectives: Insulin is recognized to increase renal salt reabsorption in the distal nephron and hyperinsulinemic states have been shown to be associated with increased expression of the renal NaCl cotransporter (NCC). However, the effect of insulin on NCC functional activity has not been reported. Methods: Using a heterologous expression system of Xenopus laevis oocytes, a mouse distal convoluted cell line, mDCT15 cells, endogenously expressing NCC, and an ex-vivo kidney perfusion technique, we assessed the effect of insulin on the activity and phosphorylation of NCC. The signaling pathway involved was analyzed. Results: In Xenopus oocytes insulin increases the activity of NCC together with its phosphorylation at threonine residue 58. Activation of NCC by insulin was also observed in mDCT15 cells. Additionally, insulin increased the NCC phosphorylation in kidney under the ex-vivo perfusion technique. In oocytes and mDCT15 cells, insulin effect on NCC was prevented with inhibitors of phosphatidylinositol 3-kinase (PI3K), mTORC2, and AKT1 kinases, but not by inhibitors of MAP or mTORC1 kinases, suggesting that PI3K-mTORC2-AKT1 is the intracellular pathway required. Additionally, activation of NCC by insulin was not affected by wild-type or mutant versions of with no lysine kinase 1, with no lysine kinase 4, or serum glucocorticoid kinase 1, but it was no longer observed in the presence of wild-type or the dominant negative, catalytically inactive with no lysine kinase 3, implicating this kinase in the process. Conclusion: Insulin induces activation and phosphorylation of NCC. This effect could play an important role in arterial hypertension associated with hyperinsulinemic states, such as obesity, metabolic syndrome, or type 2 diabetes mellitus.