Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin.
Science. 2014 May 9;344(6184):634-8. doi: 10.1126/science.1252826. Epub 2014 Apr 10.
Regulation of cell volume is critical for many cellular and organismal functions, yet the molecular identity of a key player, the volume-regulated anion channel VRAC, has remained unknown. A genome-wide small interfering RNA screen in mammalian cells identified LRRC8A as a VRAC component. LRRC8A formed heteromers with other LRRC8 multispan membrane proteins. Genomic disruption of LRRC8A ablated VRAC currents. Cells with disruption of all five LRRC8 genes required LRRC8A cotransfection with other LRRC8 isoforms to reconstitute VRAC currents. The isoform combination determined VRAC inactivation kinetics. Taurine flux and regulatory volume decrease also depended on LRRC8 proteins. Our work shows that VRAC defines a class of anion channels, suggests that VRAC is identical to the volume-sensitive organic osmolyte/anion channel VSOAC, and explains the heterogeneity of native VRAC currents.
细胞体积调节对于许多细胞和机体功能至关重要，但关键参与者——体积调节阴离子通道 VRAC 的分子身份仍然未知。哺乳动物细胞中的全基因组小干扰 RNA 筛选鉴定出 LRRC8A 是 VRAC 的一个组成部分。LRRC8A 与其他 LRRC8 多跨膜蛋白形成异二聚体。LRRC8A 的基因组缺失消除了 VRAC 电流。所有五个 LRRC8 基因缺失的细胞需要 LRRC8A 与其他 LRRC8 同工型共转染才能重建 VRAC 电流。同工型组合决定了 VRAC 的失活动力学。牛磺酸通量和调节性体积减少也依赖于 LRRC8 蛋白。我们的工作表明，VRAC 定义了一类阴离子通道，表明 VRAC 与体积敏感的有机渗透溶质/阴离子通道 VSOAC 相同，并解释了天然 VRAC 电流的异质性。
