Hypotaurine Is a Substrate of GABA Transporter Family Members GAT2/Slc6a13 and TAUT/Slc6a6.
Hypotaurine Is a Substrate of GABA Transporter Family Members GAT2/Slc6a13 and TAUT/Slc6a6.
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DOI：
10.1248/bpb.b18-00168
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发表时间：
2018-10
影响因子：
2
通讯作者：
T. Nishimura;K. Higuchi;Y. Yoshida;Yuki Sugita-Fujisawa;Kazuaki Kojima;Maiko Sugimoto;Marie Santo;M. Tomi;E. Nakashima
中科院分区：
文献类型：
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作者：
T. Nishimura;K. Higuchi;Y. Yoshida;Yuki Sugita-Fujisawa;Kazuaki Kojima;Maiko Sugimoto;Marie Santo;M. Tomi;E. Nakashima
次牛磺酸是牛磺酸的前体，也是一种生理抗氧化剂，在成人和胎儿血浆中循环。本研究的目的是澄清次牛磺酸是否是Slc6a/ γ -氨基丁酸（GABA）转运蛋白家族成员的底物。以放射性标记半胱胺和2-氨基乙硫醇双加氧酶为原料合成了放射性标记次牛磺酸。测定表达小鼠GAT1/Slc6a1、TAUT/Slc6a6、GAT3/Slc6a11、BGT1/Slc6a12和GAT2/Slc6a13的HEK293细胞对[3H]GABA、[3H]牛磺酸和[14C]次牛磺酸的摄取。TAUT和GAT2具有较强的[14C]次牛磺酸摄取活性，BGT1具有中等活性，GAT1和GAT3具有轻微但显著的活性。小鼠TAUT和GAT2的次牛磺酸摄取Michaelis常数均为11µM。经次牛磺酸预处理的表达gat2的细胞表现出对h2o2诱导的氧化应激的抗性。这些结果表明，在生理条件下，TAUT和GAT2可能是次牛磺酸跨质膜转移的主要贡献者，并且通过GAT2摄取次牛磺酸有助于细胞抵抗氧化应激。
Hypotaurine is a precursor of taurine and a physiological antioxidant that circulates in adult and fetal plasma. The purpose of the present study was to clarify whether hypotaurine is a substrate of Slc6a/gamma-aminobutyric acid (GABA) transporter family members. Radiolabeled hypotaurine was synthesized from radiolabeled cysteamine and 2-aminoethanethiol dioxygenase. The uptakes of [3H]GABA, [3H]taurine, and [14C]hypotaurine by HEK293 cells expressing mouse GAT1/Slc6a1, TAUT/Slc6a6, GAT3/Slc6a11, BGT1/Slc6a12, and GAT2/Slc6a13 were measured. TAUT and GAT2 showed strong [14C]hypotaurine uptake activity, while BGT1 showed moderate activity, and GAT1 and GAT3 showed slight but significant activity. Mouse TAUT and GAT2 both showed Michaelis constants of 11 µM for hypotaurine uptake. GAT2-expressing cells pretreated with hypotaurine showed resistance to H2O2-induced oxidative stress. These results suggest that under physiological conditions, TAUT and GAT2 would be major contributors to hypotaurine transfer across the plasma membrane, and that uptake of hypotaurine via GAT2 contributes to the cellular resistance to oxidative stress.