Format

Send to

Choose Destination
J Biol Chem. 2018 Jul 6;293(27):10757-10766. doi: 10.1074/jbc.RA118.002499. Epub 2018 May 9.

Pore-lining residues of MEC-4 and MEC-10 channel subunits tune the Caenorhabditis elegans degenerin channel's response to shear stress.

Author information

1
From the Renal-Electrolyte Division, Department of Medicine.
2
Department of Pharmacology and Chemical Biology, and.
3
Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261.
4
From the Renal-Electrolyte Division, Department of Medicine, kleyman@pitt.edu.
5
Department of Cell Biology.

Abstract

The Caenorhabditis elegans MEC-4/MEC-10 channel mediates the worm's response to gentle body touch and is activated by laminar shear stress (LSS) when expressed in Xenopus oocytes. Substitutions at multiple sites within the second transmembrane domain (TM2) of MEC-4 or MEC-10 abolish the gentle touch response in worms, but the roles of these residues in mechanosensing are unclear. The present study therefore examined the role of specific MEC-4 and MEC-10 TM2 residues in the channel's response to LSS. We found that introducing mutations within the TM2 of MEC-4 or MEC-10 not only altered channel activity, but also affected the channel's response to LSS. This response was enhanced by Cys substitutions at selected MEC-4 sites (Phe715, Gly716, Gln718, and Leu719) between the degenerin and the putative amiloride-binding sites in this subunit. In contrast, the LSS response was largely blunted in MEC-10 variants bearing single Cys substitutions in the regions preceding and following the amiloride-binding site (Gly677-Leu681), as well as with four MEC-10 touch-deficient mutations that introduced charged residues into the TM2 domain. An enhanced response to LSS was observed with a MEC-10 mutation in the putative selectivity filter. Overall, MEC-4 or MEC-10 mutants that altered the channel's LSS response are primarily clustered between the degenerin site and the selectivity filter, a region that probably forms the narrowest portion of the channel pore. Our results suggest that pore-lining residues of MEC-4 and MEC-10 have important yet different roles in tuning the channel's response to mechanical forces.

KEYWORDS:

acid sensing ion channel (ASIC); degenerin; epithelial sodium channel (ENaC); gating; mechanotransduction; pore; shear stress

PMID:
29743244
PMCID:
PMC6036219
[Available on 2019-07-06]
DOI:
10.1074/jbc.RA118.002499

Supplemental Content

Full text links

Icon for HighWire
Loading ...
Support Center