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Cav3.2 calcium channel interactions with the epithelial sodium channel ENaC.

ABSTRACT: This study describes the functional interaction between Cav3.2 calcium channels and the Epithelial Sodium Channel (ENaC). ?-ENaC subunits showed overlapping expression with endogenous Cav3.2 calcium channels in the thalamus and hypothalamus as detected by immunostaining. Moreover, ?- and ?-ENaC subunits could be co-immunoprecipitated with Cav3.2 calcium channels from brain lysates, dorsal horn and lumbar dorsal root ganglia. Mutation of a cluster of lysines present in the intracellular N-terminus region of ?-ENaC (K4R/ K5R/ K9R/ K16R/ K23R) reduced interactions with Cav3.2 calcium channels. ???-ENaC channels enhanced Cav3.2 calcium channel trafficking to the plasma membrane in tsA-201 cells. This effect was reciprocal such that Cav3.2 channel expression also enhanced ?-ENaC trafficking to the cell surface. T-type current density was increased when fully assembled ???-ENaC channels were transiently expressed in CAD cells, a neuronal derived cell line. Altogether, these findings reveal ENaC as an interactor and potential regulator of Cav3.2 calcium channels expressed in neuronal tissues.

SUBMITTER: Garcia-Caballero A

PROVIDER: S-EPMC6368719 | biostudies-literature | 2019 Feb

REPOSITORIES: biostudies-literature

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Salt-deficient diet exacerbates cystogenesis in ARPKD via epithelial sodium channel (ENaC).

Project description:BACKGROUND:Autosomal Recessive Polycystic Kidney Disease (ARPKD) is marked by cyst formation in the renal tubules, primarily in the collecting duct (CD) system, ultimately leading to end-stage renal disease. Patients with PKD are generally advised to restrict their dietary sodium intake. This study was aimed at testing the outcomes of dietary salt manipulation in ARPKD. METHODS:PCK/CrljCrlPkhd1pck/CRL (PCK) rats, a model of ARPKD, were fed a normal (0.4% NaCl; NS), high salt (4% NaCl; HS), and sodium-deficient (0.01% NaCl; SD) diets for 8 weeks. Immunohistochemistry, GFR measurements, balance studies, and molecular biology approaches were applied to evaluate the outcomes of the protocol. Renin-angiotensin-aldosterone system (RAAS) levels were assessed using LC-MS/MS, and renal miRNA profiles were studied. FINDINGS:Both HS and SD diets resulted in an increase in cystogenesis. However, SD diet caused extensive growth of cysts in the renal cortical area, and hypertrophy of the tissue; RAAS components were enhanced in the SD group. We observed a reduction in epithelial Na+ channel (ENaC) expression in the SD group, accompanied with mRNA level increase. miRNA assay revealed that renal miR-9a-5p level was augmented in the SD group; we showed that this miRNA decreases ENaC channel number in CD cells. INTERPRETATION:Our data demonstrate a mechanism of ARPKD progression during salt restriction that involves activity of ENaC. We further show that miR-9a-5p potentially implicated in this mechanism and that miR-9a-5p downregulates ENaC in cultured CD cells. Our findings open new therapeutic possibilities and highlight the importance of understanding salt reabsorption in ARPKD.

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The epithelial sodium channel (ENaC) establishes a trafficking vesicle pool responsible for its regulation.

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