ENaC Activity is Regulated by Calpain-2 Proteolysis of MARCKS Proteins
Overview
Physiology
Authors
Affiliations
We previously demonstrated a role for the myristoylated alanine-rich C kinase substrate (MARCKS) to serve as an adaptor protein in the anionic phospholipid phosphate-dependent regulation of the epithelial sodium channel (ENaC). Both MARCKS and ENaC are regulated by proteolysis. Calpains are a family of ubiquitously expressed intracellular Ca-dependent cysteine proteases involved in signal transduction. Here we examine the role of calpain-2 in regulating MARCKS and ENaC in cultured renal epithelial cells and in the mouse kidney. Using recombinant fusion proteins, we show that MARCKS, but not the ENaC subunits, are a substrate of calpain-2 in the presence of Ca Pharmacological inhibition of calpain-2 alters MARCKS protein expression in light-density sucrose gradient fractions from cell lysates of mouse cortical collecting duct cells. Calpain-dependent cleaved products of MARCKS are detectable in cultured renal cells. Ca mobilization and calpain-2 inhibition decrease the association between ENaC and MARCKS. The inhibition of calpain-2 reduces ENaC activity as demonstrated by single-channel patch-clamp recordings and transepithelial current measurements. These results suggest that calpain-2 proteolysis of MARCKS promotes its interaction with lipids and ENaC at the plasma membrane to allow for the phosphatidylinositol 4,5-bisphosphate (PIP2)-dependent regulation of ENaC activity in the kidney.
Dogan Y, Bala N, Galban E, Lewis R, Denslow N, Song S Front Mol Biosci. 2025; 11:1485506.
PMID: 39902374 PMC: 11788078. DOI: 10.3389/fmolb.2024.1485506.
Kokesh K, Bala N, Dogan Y, Nguyen V, Costa M, Alli A PLoS One. 2024; 19(10):e0308299.
PMID: 39413095 PMC: 11482691. DOI: 10.1371/journal.pone.0308299.
PIEZO1 is a distal nephron mechanosensor and is required for flow-induced K+ secretion.
Carrisoza-Gaytan R, Mutchler S, Carattino F, Soong J, Dalghi M, Wu P J Clin Invest. 2024; 134(5).
PMID: 38426496 PMC: 10904061. DOI: 10.1172/JCI174806.
Proteolytic Activation of the Epithelial Sodium Channel (ENaC): Its Mechanisms and Implications.
Aufy M, Hussein A, Stojanovic T, Studenik C, Kotob M Int J Mol Sci. 2023; 24(24).
PMID: 38139392 PMC: 10743461. DOI: 10.3390/ijms242417563.
Al-Humiari M, Yu L, Liu L, Nouri M, Tuna K, Denslow N Biochim Biophys Acta Biomembr. 2023; 1866(1):184219.
PMID: 37634857 PMC: 11632644. DOI: 10.1016/j.bbamem.2023.184219.