Distinct pharmacological and molecular properties of the acid-sensitive outwardly rectifying (ASOR) anion channel from those of the volume-sensitive outwardly rectifying (VSOR) anion channel
Distinct pharmacological and molecular properties of the acid-sensitive outwardly rectifying (ASOR) anion channel from those of the volume-sensitive outwardly rectifying (VSOR) anion channel
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DOI：
10.1007/s00424-015-1786-1
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发表时间：
2016-01
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影响因子：
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通讯作者：
Kaori Sato-Numata;T. Numata;R. Inoue;Yasunobu Okada
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作者：
Kaori Sato-Numata;T. Numata;R. Inoue;Yasunobu Okada
酸敏感性外向整流（ASOR）阴离子通道在多种细胞类型中表达，已知其被细胞外酸化激活并参与酸毒性坏死细胞死亡。相反，普遍表达的体积敏感性外向整流（VSOR）阴离子通道被渗透性细胞肿胀激活，并参与细胞体积调节和凋亡细胞死亡。区分ASOR和VSOR阴离子通道的不同抑制剂尚未确定。虽然最近发现富含亮氨酸的重复序列包含8A（LRRC 8A）是VSOR阴离子通道的重要组成部分，LRRC 8家族成员作为ASOR阴离子通道的组成部分的可能性尚未被检查。在这项研究中，我们探讨了12个已知的VSOR通道抑制剂和小干扰RNA（siRNA）介导的LRRC 8家族成员的敲低对HeLa细胞ASOR和VSOR电流的影响。在这些抑制剂中，八种推定的VSOR阻断剂，包括4-（2-丁基-6，7-三氯-2-环戊基茚满-1-酮-5-基）氧代丁酸（DCPIB）和5-硝基-2-（3-苯基丙基氨基）-苯甲酸（NPPB）完全不能阻断ASOR通道活性，而苏拉明、R-（+）-[（2-n-丁基-6，7-二氯-2-环戊基-2，3-二氢-1-氧代-1H-茚-5-基）氧基]乙酸（DIOA）、花生四烯酸和尼氟灭酸被发现是有效的ASOR阴离子通道拮抗剂。此外，基因沉默研究表明，没有LRRC 8家族成员基本上参与ASOR阴离子通道活性，而LRRC 8A参与HeLa细胞中的VSOR阴离子通道活性。
Expressed by many cell types, acid-sensitive outwardly rectifying (ASOR) anion channels are known to be activated by extracellular acidification and involved in acidotoxic necrotic cell death. In contrast, ubiquitously expressed volume-sensitive outwardly rectifying (VSOR) anion channels are activated by osmotic cell swelling and involved in cell volume regulation and apoptotic cell death. Distinct inhibitors to distinguish ASOR from VSOR anion channels have not been identified. Although leucine-rich repeats containing 8A (LRRC8A) was recently found to be an essential component of VSOR anion channels, the possibility of an LRRC8 family member serving as a component of ASOR anion channels has not been examined. In this study, we explored the effects of 12 known VSOR channel inhibitors and small interfering RNA (siRNA)-mediated knockdown of LRRC8 family members on ASOR and VSOR currents in HeLa cells. Among these inhibitors, eight putative VSOR blockers, including 4-(2-butyl-6,7-dichlor-2-cyclopentylindan-1-on-5-yl) oxobutyric acid (DCPIB) and 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB), were totally ineffective at blocking ASOR channel activity, whereas suramin,R-(+)-[(2-n-butyl-6,7-dichloro-2-cyclopentyl-2,3-dihydro-1-oxo-1H-inden-5-yl)oxy] acetic acid (DIOA), arachidonic acid, and niflumic acid were found to be effective ASOR anion channel antagonists. In addition, gene-silencing studies showed that no LRRC8 family members are essentially involved in ASOR anion channel activity, whereas LRRC8A is involved in VSOR anion channel activity in HeLa cells.