Maxi-anion channel and pannexin 1 hemichannel constitute separate pathways for swelling-induced ATP release in murine L929 fibrosarcoma cells.
Maxi-anion channel and pannexin 1 hemichannel constitute separate pathways for swelling-induced ATP release in murine L929 fibrosarcoma cells.
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DOI：
10.1152/ajpcell.00459.2011
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发表时间：
2012-11
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影响因子：
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通讯作者：
Md. Rafiqul Islam;H. Uramoto;Toshiaki Okada;R. Sabirov;Y. Okada
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作者：
Md. Rafiqul Islam;H. Uramoto;Toshiaki Okada;R. Sabirov;Y. Okada
最大阴离子通道在通过氯电导控制膜电位方面发挥着经典的作用。它还具有作为从受到渗透扰动、缺血或缺氧的细胞释放阴离子信号分子 ATP 和兴奋性氨基酸的调节途径的新功能。因为据报道，由pannexins和connexins形成的半通道可以介导多种细胞类型的ATP释放，这些半通道可能代表了maxi-阴离子通道的分子相关性。在这里，我们发现 L929 纤维肉瘤细胞表达功能性 maxi-阴离子通道，介导肿胀诱导的 ATP 释放的主要部分，并且通过 maxi-阴离子通道释放的 ATP 促进渗透性肿胀后调节体积的减少。此外，还发现细胞表达 pannexin 1、pannexin 2 和 connexin 43 的 mRNA。低渗性诱导的 ATP 释放不仅受到已知的 maxi-阴离子通道阻断剂的部分抑制，而且还受到几种 pannexin 阻断剂的抑制，包括 pannexin 1 特异性阻断肽 (10)Panx1 和针对 pannexin 1 但不针对 pannexin 2 的小干扰 (si)RNA。 maxi-阴离子通道阻滞剂和 pannexin 1 拮抗剂是相加的。相反，最大阴离子通道活性不受pannexin 1拮抗剂和针对pannexins 1和2的siRNA的影响。尽管连接蛋白43特异性阻断肽Gap27轻微抑制低渗诱导的ATP释放，但最大阴离子通道活性不受Gap27或连接蛋白43特异性siRNA影响。因此，得出的结论是，maxi-阴离子通道是不同于pannexin 1、pannexin 2和connexin 43的分子实体，并且maxi-阴离子通道和半通道构成了L929细胞中肿胀诱导的ATP释放的单独途径。
The maxi-anion channel plays a classically recognized role in controlling the membrane potential through the chloride conductance. It also has novel functions as a regulated pathway for the release of the anionic signaling molecules ATP and excitatory amino acids from cells subjected to osmotic perturbation, ischemia, or hypoxia. Because hemichannels formed by pannexins and connexins have been reported to mediate ATP release from a number of cell types, these hemichannels may represent the molecular correlate of the maxi-anion channel. Here, we found that L929 fibrosarcoma cells express functional maxi-anion channels which mediate a major portion of swelling-induced ATP release, and that ATP released via maxi-anion channels facilitates the regulatory volume decrease after osmotic swelling. Also, it was found that the cells express the mRNA for pannexin 1, pannexin 2, and connexin 43. Hypotonicity-induced ATP release was partially suppressed not only by known blockers of the maxi-anion channel but also by several blockers of pannexins including the pannexin 1-specific blocking peptide (10)Panx1 and small interfering (si)RNA against pannexin 1 but not pannexin 2. The inhibitory effects of maxi-anion channel blockers and pannexin 1 antagonists were additive. In contrast, maxi-anion channel activity was not affected by pannexin 1 antagonists and siRNAs against pannexins 1 and 2. Although a connexin 43-specific blocking peptide, Gap27, slightly suppressed hypotonicity-induced ATP release, maxi-anion channel activity was not affected by Gap27 or connexin 43-specific siRNA. Thus, it is concluded that the maxi-anion channel is a molecular entity distinct from pannexin 1, pannexin 2, and connexin 43, and that the maxi-anion channel and the hemichannels constitute separate pathways for swelling-induced ATP release in L929 cells.