Role of the alternative splice variant of NCC in blood pressure control

Cryo-EM structure of the human sodium-chloride cotransporter NCC

The sodium-chloride cotransporter NCC mediates the coupled import of sodium and chloride across the plasma membrane, playing vital roles in kidney extracellular fluid volume and blood pressure control. Here, we present the full-length structure of human NCC, with 2.9 Å for the transmembrane domain and 3.8 Å for the carboxyl-terminal domain. NCC adopts an inward-open conformation and a domain-swap dimeric assembly. Conserved ion binding sites among the cation-chloride cotransporters and the Na2 site are observed in our structure. A unique His residue in the substrate pocket in NCC potentially interacts with Na1 and Cl1 and might also mediate the coordination of Na2 through a Ser residue. Putative observed water molecules are indicated to participate in the coordination of ions and TM coupling. Together with transport activity assays, our structure provides the first glimpse of NCC and defines ion binding sites, promoting drug development for hypertension targeting on NCC.

The Post-Translational Modification Networking in WNK-Centric Hypertension Regulation and Electrolyte Homeostasis

The with-no-lysine (WNK) kinase family, comprising four serine-threonine protein kinases (WNK1-4), were first linked to hypertension due to their mutations in association with pseudohypoaldosteronism type II (PHAII). WNK kinases regulate crucial blood pressure regulators, SPAK/OSR1, to mediate the post-translational modifications (PTMs) of their downstream ion channel substrates, such as sodium chloride co-transporter (NCC), epithelial sodium chloride (ENaC), renal outer medullary potassium channel (ROMK), and Na/K/2Cl co-transporters (NKCCs). In this review, we summarize the molecular pathways dysregulating the WNKs and their downstream target renal ion transporters. We summarize each of the genetic variants of WNK kinases and the small molecule inhibitors that have been discovered to regulate blood pressure via WNK-triggered PTM cascades.

Urinary extracellular vesicle mRNA analysis of sodium chloride cotransporter in hypertensive patients under different conditions

Urinary extracellular vesicles (UEV) mainly derive from cells of the urogenital tract and their cargo (proteins, nucleic acids, lipids, etc.) reflects their cells of origin. Na chloride cotransporter (NCC) is expressed at the kidney level in the distal convoluted tubule, is involved in salt reabsorption, and is the target of the diuretic thiazides. NCC protein has been recognized and quantified in UEV in previous studies; however, UEV NCC mRNA has never been studied. This study aimed to identify and analyze NCC mRNA levels in primary aldosteronism (PA). The rationale for this investigation stems from previous observations regarding NCC (protein) as a possible biomarker for the diagnosis of PA. To evaluate modulations in the expression of NCC, we analyzed NCC mRNA levels in UEV in PA and essential hypertensive (EH) patients under different conditions, that is, before and after saline infusion, anti-aldosterone pharmacological treatment, and adrenal surgery. NCC mRNA was measured by RT-qPCR in all the samples and was regulated by volume expansion. Its response to mineralocorticoid receptor antagonist was correlated with renin, and it was increased in PA patients after adrenalectomy. NCC mRNA is evaluable in UEV and it can provide insights into the pathophysiology of distal convolute tubule in different clinical conditions including PA.