Integrated compensatory network is activated in the absence of NCC phosphorylation

• Authors: P. Richard Grimm, University of Maryland; Yoskaly Lazo-Fernandez, Emory University; Eric Delpire, Vanderbilt University; Susan Wall, Emory University; Susan G. Dorsey, University of Maryland; Edward J. Weinman, University of Maryland; Richard Coleman, University of Maryland; James B. Wade, University of Maryland; Paul A. Welling, University of Maryland
• Journal Title: Journal of Clinical Investigation
• Volume: Volume 125, Number 5
• Publisher: American Society for Clinical Investigation | 2015-05-01, Pages 2136-2150
• Type of Work: Article | Final Publisher PDF
• Publisher DOI: http://doi.org/10.1172/JCI78558
• Subjects: Biology, Physiology; Biology, Genetics
• Keywords: Science & Technology; Life Sciences & Biomedicine; Medicine, Research & Experimental; Research & Experimental Medicine; NA+-CL-COTRANSPORTER; SODIUM-CHLORIDE COTRANSPORTER; SALT-SENSITIVE HYPERTENSION; ORGANIC ANION TRANSPORTERS; CORTICAL COLLECTING DUCTS; BLOOD-PRESSURE REGULATION; DISTAL CONVOLUTED TUBULE; RENAL INTERCALATED CELLS; AMINO-ACID TRANSPORTER; ANGIOTENSIN-II; Nephrology

Abstract

Thiazide diuretics are used to treat hypertension; however, compensatory processes in the kidney can limit antihypertensive responses to this class of drugs. Here, we evaluated compensatory pathways in SPAK kinase-deficient mice, which are unable to activate the thiazide-sensitive sodium chloride cotransporter NCC (encoded by Slc12a3). Global transcriptional profiling, combined with biochemical, cell biological, and physiological phenotyping, identified the gene expression signature of the response and revealed how it establishes an adaptive physiology. Salt reabsorption pathways were created by the coordinate induction of a multigene transport system, involving solute carriers (encoded by Slc26a4, Slc4a8, and Slc4a9), carbonic anhydrase isoforms, and V-type H⁺-ATPase subunits in pendrin-positive intercalated cells (PP-ICs) and ENaC subunits in principal cells (PCs). A distal nephron remodeling process and induction of jagged 1/NOTCH signaling, which expands the cortical connecting tubule with PCs and replaces acid-secreting α-ICs with PP-ICs, were partly responsible for the compensation. Salt reabsorption was also activated by induction of an α-ketoglutarate (α-KG) paracrine signaling system. Coordinate regulation of a multigene α-KG synthesis and transport pathway resulted in α-KG secretion into pro-urine, as the α-KG-activated GPCR (Oxgr1) increased on the PP-IC apical surface, allowing paracrine delivery of α-KG to stimulate salt transport. Identification of the integrated compensatory NaCl reabsorption mechanisms provides insight into thiazide diuretic efficacy.