The Volume-Regulated Anion Channel LRRC8/VRAC Is Dispensable for Cell Proliferation and Migration.

Tianbao Liu,Tobias Stauber

doi:10.3390/ijms20112663

Abstract

Cells possess the capability to adjust their volume for various physiological processes, presumably including cell proliferation and migration. The volume-regulated anion channel (VRAC), formed by LRRC8 heteromers, is critically involved in regulatory volume decrease of vertebrate cells. The VRAC has also been proposed to play a role in cell cycle progression and cellular motility. Indeed, recent reports corroborated this notion, with potentially important implications for the VRAC in cancer progression. In the present study, we examined the role of VRAC during cell proliferation and migration in several cell types, including C2C12 myoblasts, human colon cancer HCT116 cells, and U251 and U87 glioblastoma cells. Surprisingly, neither pharmacological inhibition of VRAC with 4-[(2-Butyl-6,7-dichloro-2-cyclopentyl-2,3-dihydro-1-oxo-1H-inden-5-yl)oxy]butanoic acid (DCPIB), carbenoxolone or 5-nitro-2-(3-phenylpropyl-amino)benzoic acid (NPPB), nor siRNA-mediated knockdown or gene knockout of the essential VRAC subunit LRRC8A affected cell growth and motility in any of the investigated cell lines. Additionally, we found no effect of the VRAC inhibition using siRNA treatment or DCPIB on PI3K/Akt signaling in glioblastoma cells. In summary, our work suggests that VRAC is dispensable for cell proliferation or migration.

Highlights

The volume-regulated anion channel (VRAC), alternatively named the volume-sensitive outwardly rectifying (VSOR) anion channel, is ubiquitously expressed in almost all vertebrate cells [1,2,3]
To study the potential role of VRAC in cell proliferation and migration, and we systematically examined these processes for a variety of cell lines, including cancer and noncancer cell lines, by using pharmacological blockers, siRNA against LRRC8A, and genomic VRAC knockout
The proliferation rate of the knockout clones was similar to that of wild-type cells or the heterozygous clone (Figure 1B), demonstrating that VRAC is dispensable for C2C12 cell proliferation

Summary

Introduction

The volume-regulated anion channel (VRAC), alternatively named the volume-sensitive outwardly rectifying (VSOR) anion channel, is ubiquitously expressed in almost all vertebrate cells [1,2,3]. The channel opens upon osmotic cell swelling and contributes to regulatory volume decrease (RVD) by releasing chloride ions and various organic osmolytes [1,2,3,7,8,9]. Osmotic water flux by the differential activity of ion channels and transporters mediating local changes in cell volume was found to contribute to cell movement [20,21]. The uptake of inorganic ions and water (a regulatory volume increase, RVI) at the leading edge by locally active Na+-K+-2Cl− cotransport, Na+/H+ exchange or nonselective cation channels, and a volume decrease at the trailing end via release of K+ and Cl− through activated K+ and Cl− channels followed by water efflux (RVD) will lead to a net translocation of the cell [22]. Cell displacement was found to be solely driven by directed cellular osmotic water transport in an artificial confined environment when actin polymerization was inhibited [23]

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Results

Conclusion