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Tweety-homolog ( Ttyh ) Family Encodes the Pore-forming Subunits of the Swelling-dependent Volume-regulated Anion Channel (VRAC swell ) in the Brain

2019; Volume: 28; Issue: 2 Linguagem: Inglês

10.5607/en.2019.28.2.183

2093-8144

Young-Eun Han, Jea Kwon, Joungha Won, Heeyoung An, Minwoo Wendy Jang, Junsung Woo, Je Sun Lee, Min Gu Park, Bo-Eun Yoon, Seung Eun Lee, Eun Mi Hwang, Jae Young Jung, Hyungju Park, Soo‐Jin Oh, C. Justin Lee,

Lipid Membrane Structure and Behavior

In the brain, a reduction in extracellular osmolality causes water-influx and swelling, which subsequently triggers Cl-- and osmolytes-efflux via volume-regulated anion channel (VRAC). Although LRRC8 family has been recently proposed as the pore-forming VRAC which is activated by low cytoplasmic ionic strength but not by swelling, the molecular identity of the pore-forming swelling-dependent VRAC (VRACswell) remains unclear. Here we identify and characterize Tweety-homologs (TTYH1, TTYH2, TTYH3) as the major VRACswell in astrocytes. Gene-silencing of all Ttyh1/2/3 eliminated hypo-osmotic-solution-induced Cl- conductance (ICl,swell) in cultured and hippocampal astrocytes. When heterologously expressed in HEK293T or CHO-K1 cells, each TTYH isoform showed a significant ICl,swell with similar aquaporin-4 dependency, pharmacological properties and glutamate permeability as ICl,swell observed in native astrocytes. Mutagenesis-based structure-activity analysis revealed that positively charged arginine residue at 165 in TTYH1 and 164 in TTYH2 is critical for the formation of the channel-pore. Our results demonstrate that TTYH family confers the bona fide VRACswell in the brain.