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

Agustin Garcia-Caballero,Shuo Huang,Shuo Huang,Maria A Gandini,Gerald W Zamponi,Gerald W Zamponi,M Jackson Stutts,Yan L Dang,Lina Chen,Lina Chen,Ivana A Souza,Ivana A Souza

doi:10.1186/s13041-019-0433-8

Agustin Garcia-Caballero, Shuo Huang + Show 10 more

Open Access

https://doi.org/10.1186/s13041-019-0433-8

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Abstract

This study describes the functional interaction between Cav3.2 calcium channels and the Epithelial Sodium Channel (ENaC). β-ENaC subunits showed overlapping expression with endogenous Cav3.2 calcium channels in the thalamus and hypothalamus as detected by immunostaining. Moreover, β- and γ-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 β-ENaC (K4R/ K5R/ K9R/ K16R/ K23R) reduced interactions with Cav3.2 calcium channels. Αβγ-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 β-ENaC trafficking to the cell surface. T-type current density was increased when fully assembled αβγ-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.

Highlights

The Epithelial Sodium Channel (ENaC) is a key regulator of sodium absorption in a variety of tissues
Cav3.2 channels and ENaC subunits interact Because there are several reports in the literature regarding the overlapping expression of both ENaC and Cav3.2 calcium channels in the brain, we first probed Cav3.2 immunoprecipitates from whole brain lysates with either α, β, or γ- ENaC antibodies. β- and γ- ENaC subunits bound to Cav3.2 channels were consistently detected (Fig. 1a-d)
We detected a strong co-localization in the hypothalamus where 591out of 618 cells co-stained for both Cav3.2 calcium channels and β-ENaC subunits

Summary

Introduction

The Epithelial Sodium Channel (ENaC) is a key regulator of sodium absorption in a variety of tissues. It fine tunes sodium in the nephron and the colonic epithelia [1] where it helps to maintain total body salt and volume homeostasis. In the pulmonary airway epithelia ENaC regulates the composition and depth of the airway surface liquid to maintain mucociliary clearance [2, 3]. Malfunction of ENaC in these tissues results in various cardiovascular [4] and lung diseases, such as cystic fibrosis [5]. Gain or loss of function mutations in all ENaC subunits result in disorders such as hypertension or Liddle’s Syndrome and pseudohypoaldosteronism [4, 7]

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