GlialCAM/MLC1 modulates LRRC8/VRAC currents in an indirect manner: Implications for megalencephalic leukoencephalopathy

Neurobiol Dis. 2018 Nov:119:88-99. doi: 10.1016/j.nbd.2018.07.031. Epub 2018 Aug 1.


Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a rare type of leukodystrophy caused by mutations in either MLC1 or GLIALCAM genes. Previous work indicated that chloride currents mediated by the volume-regulated anion channel (VRAC) and ClC-2 channels were affected in astrocytes deficient in either Mlc1 or Glialcam. ClC-2 forms a ternary complex with GlialCAM and MLC1. LRRC8 proteins have been identified recently as the molecular components of VRAC, but the relationship between MLC and LRRC8 proteins is unknown. Here, we first demonstrate that LRRC8 and MLC1 are functionally linked, as MLC1 cannot potentiate VRAC currents when LRRC8A, the main subunit of VRAC, is knocked down. We determine that LRRC8A and MLC1 do not co-localize or interact and, in Xenopus oocytes, MLC1 does not potentiate LRRC8-mediated VRAC currents, indicating that VRAC modulation in astrocytes by MLC1 may be indirect. Investigating the mechanism of modulation, we find that a lack of MLC1 does not influence either mRNA or total and plasma membrane protein levels of LRRC8A; and neither does it affect LRRC8A subcellular localization. In agreement with recent results that indicated that overexpression of MLC1 decreases the phosphorylation of extracellular signal-regulated kinases (ERK), we find that astrocytes lacking MLC1 show an increase in ERK phosphorylation. In astrocytes with reduced or increased levels of MLC1 we observe changes in the phosphorylation state of the VRAC subunit LRRC8C. Our results thus reinforce previous suggestions that indicated that GlialCAM/MLC1 might modify signal transduction pathways that influence the activity of different proteins, such as VRAC.

Keywords: Astrocytes; ERK; GlialCAM; LRRC8; Leukodystrophy; MLC1; Signal transduction; Volume-regulated anion channel.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / analysis
  • Adaptor Proteins, Signal Transducing / genetics
  • Adaptor Proteins, Signal Transducing / metabolism*
  • Amino Acid Sequence
  • Animals
  • Astrocytes / chemistry
  • Astrocytes / metabolism*
  • Astrocytes / pathology
  • Cell Cycle Proteins
  • Cells, Cultured
  • Cysts / metabolism*
  • Cysts / pathology
  • HeLa Cells
  • Hereditary Central Nervous System Demyelinating Diseases / metabolism*
  • Hereditary Central Nervous System Demyelinating Diseases / pathology
  • Humans
  • Membrane Proteins / analysis
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Proteins / analysis
  • Proteins / genetics
  • Proteins / metabolism*
  • Rats
  • Xenopus


  • Adaptor Proteins, Signal Transducing
  • Cell Cycle Proteins
  • HEPACAM protein, human
  • LRRC8A protein, human
  • MLC1 membrane protein, rat
  • Membrane Proteins
  • Proteins
  • SH2D2A protein, human

Supplementary concepts

  • Megalencephalic leukoencephalopathy with subcortical cysts