Nakajima Ken-Ichi, Marunaka Yoshinori
Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Kyoto 602-8566, Japan.
Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Kyoto 602-8566, Japan; Department of Bio-Ionomics, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Kyoto 602-8566, Japan.
Biochem Biophys Res Commun. 2016 Oct 14;479(2):338-342. doi: 10.1016/j.bbrc.2016.09.075. Epub 2016 Sep 15.
Chloride ion (Cl) is one of the most abundant anions in our body. Increasing evidence suggests that Cl plays fundamental roles in various cellular functions. We have previously reported that electroneutral cation-chloride cotransporters, such as Na-K-2Cl cotransporter 1 (NKCC1) and K-Cl cotransporter 1 (KCC1), are involved in neurite outgrowth during neuronal differentiation. In the present study, we studied if there is correlation between intracellular Cl concentrations ([Cl]) and the length of growing neurites. We measured [Cl] in the cell body and growing neurite tips using halide-sensitive fluorescent dye N-(ethoxycarbonylmethyl)-6-methoxyquinolinium bromide (MQAE), revealing that [Cl] in the tip of growing neurite was higher than that in cell body in a single cell. Importantly, there was a significant positive correlation between the length of growing neurite and [Cl] in neurite tip. Bumtanide (BMT), an inhibitor of NKCC1, significantly inhibited neurite outgrowth and decreased [Cl] in neurite tip. The results obtained in the present study and our previous studies together strongly suggest that high [Cl] in neurite tip region is crucial for efficient neurite outgrowth.
氯离子（Cl）是人体中含量最丰富的阴离子之一。越来越多的证据表明，Cl在各种细胞功能中发挥着重要作用。我们之前曾报道，电中性阳离子-氯离子共转运体，如钠-钾-2氯共转运体1（NKCC1）和钾-氯共转运体1（KCC1），参与神经元分化过程中的神经突生长。在本研究中，我们研究了细胞内Cl浓度（[Cl]）与生长中的神经突长度之间是否存在相关性。我们使用卤化物敏感荧光染料N-（乙氧羰基甲基）-6-甲氧基喹啉溴化物（MQAE）测量了细胞体和生长中的神经突尖端的[Cl]，结果显示在单个细胞中，生长中的神经突尖端的[Cl]高于细胞体中的[Cl]。重要的是，生长中的神经突长度与神经突尖端的[Cl]之间存在显著的正相关。布美他尼（BMT），一种NKCC1抑制剂，显著抑制神经突生长并降低神经突尖端的[Cl]。本研究和我们之前研究所得结果共同有力地表明，神经突尖端区域的高[Cl]对于有效的神经突生长至关重要。
