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ENaC activity is regulated by calpain-2 proteolysis of MARCKS proteins.


ABSTRACT: 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 Ca2+-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 Ca2+ 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. Ca2+ 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.

SUBMITTER: Montgomery DS 

PROVIDER: S-EPMC5538800 | biostudies-literature | 2017 Jul

REPOSITORIES: biostudies-literature

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ENaC activity is regulated by calpain-2 proteolysis of MARCKS proteins.

Montgomery Darrice S DS   Yu Ling L   Ghazi Zinah M ZM   Thai Tiffany L TL   Al-Khalili Otor O   Ma He-Ping HP   Eaton Douglas C DC   Alli Abdel A AA  

American journal of physiology. Cell physiology 20170503 1


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<sup>2+</sup>-dependent cysteine proteases involved in signal transduction. Here we examine the role of calpain-2 in regulating MARCKS and ENaC in cultured r  ...[more]

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