The volume-regulated anion channel (LRRC8) in nodose neurons is sensitive to acidic pH

JCI Insight. 2017 Mar 9;2(5):e90632. doi: 10.1172/jci.insight.90632.

Abstract

The leucine rich repeat containing protein 8A (LRRC8A), or SWELL1, is an essential component of the volume-regulated anion channel (VRAC) that is activated by cell swelling and ionic strength. We report here for the first time to our knowledge its expression in a primary cell culture of nodose ganglia neurons and its localization in the soma, neurites, and neuronal membrane. We show that this neuronal VRAC/SWELL1 senses low external pH (pHo) in addition to hypoosmolarity. A robust sustained chloride current is seen in 77% of isolated nodose neurons following brief exposures to extracellular acid pH. Its activation involves proton efflux, intracellular alkalinity, and an increase in NOX-derived H2O2. The molecular identity of both the hypoosmolarity-induced and acid pHo-conditioned VRAC as LRRC8A (SWELL1) was confirmed by Cre-flox-mediated KO, shRNA-mediated knockdown, and CRISPR/Cas9-mediated LRRC8A deletion in HEK cells and in primary nodose neuronal cultures. Activation of VRAC by low pHo reduces neuronal injury during simulated ischemia and N-methyl-D-aspartate-induced (NMDA-induced) apoptosis. These results identify the VRAC (LRRC8A) as a dual sensor of hypoosmolarity and low pHo in vagal afferent neurons and define the mechanisms of its activation and its neuroprotective potential.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Acids / chemistry
  • Animals
  • Cells, Cultured
  • Chlorides / metabolism
  • Ganglia, Spinal / cytology
  • Ganglia, Spinal / metabolism
  • HEK293 Cells
  • Humans
  • Hydrogen Peroxide / metabolism
  • Hydrogen-Ion Concentration*
  • Ischemic Preconditioning
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Mice
  • NADPH Oxidases / metabolism
  • Neurons / metabolism*
  • Osmolar Concentration
  • Patch-Clamp Techniques
  • RNA, Messenger / genetics

Substances

  • Acids
  • Chlorides
  • LRRC8A protein, mouse
  • Membrane Proteins
  • RNA, Messenger
  • Hydrogen Peroxide
  • NADPH Oxidases