Mitochondria are intracellular magnesium stores: investigation by simultaneous fluorescent imagings in PC12 cells
Mitochondria are intracellular magnesium stores: investigation by simultaneous fluorescent imagings in PC12 cells
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DOI：
10.1016/j.bbamcr.2004.10.013
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发表时间：
2005-05-15
影响因子：
5.1
通讯作者：
Oka, K
中科院分区：
文献类型：
--
作者：
Kubota, T;Shindo, Y;Oka, K
为了确定分化的PC12细胞内Mg2+储存的性质和Mg2+释放机制，分别用荧光Mg2+指示剂KMG-104和fura-2同时测量活细胞中Mg2+和Ca2+的动员。用线粒体解偶联剂羰基氰化物对-（三氟甲氧基）苯腙（FCCP）处理，增加了这些细胞内Mg2+浓度（[Mg2+](i)）和[Ca2+](i)。在这些条件下，可能作为细胞内Mg2+储存的候选者包括细胞内二价阳离子结合位点、内质网（ER）、Mg-ATP和线粒体。鉴于咖啡因应用、细胞内IP3或光解释放的Ca2+没有引起[Mg2+](i)的变化，因此似乎不存在通过内质网中Ca2+对膜结合受体的作用或由于[Ca2+]增加而从结合位点卸载Mg2+ (i)介导的Mg2+释放机制。FCCP处理2分钟没有改变细胞内ATP含量，这表明Mg2+没有从Mg-ATP中释放出来，至少在FCCP暴露后的前2分钟是这样。fccp诱导线粒体局部区域[Mg2+](i)升高，反之亦然。这些结果表明，线粒体在PC12细胞中起着细胞内Mg2+储存的作用。同时测量[Ca2+](i)和线粒体膜电位，以及[Ca2+](i)和[Mg2+](i)，表明[Mg2+](i)的初始上升是在线粒体去极化之后的几秒钟。这些发现表明，fccp诱导的PC12细胞[Mg2+](i)增加中Mg2+的来源是线粒体，线粒体去极化触发Mg2+释放。(c) 2004 Elsevier b.v.版权所有
To determine the nature of intracellular Mg2+ stores and Mg2+ release mechanisms in differentiated PC12 cells, Mg2+ and Ca2+ mobilizations were measured simultaneously in living cells with KMG-104, a fluorescent Mg2+ indicator, and fura-2, respectively. Treatment with the mitochondrial uncoupler, carbonyl cyanide p-(trifluoromethoxy) phenylhydrazone (FCCP), increased both the intracellular Mg2+ concentration ([Mg2+](i)) and the [Ca2+](i) in these cells. Possible candidates as intracellular Mg2+ stores under these conditions include intracellular divalent cation binding sites, endoplasmic reticulum (ER), Mg-ATP and mitochondria. Given that no change in [Mg2+](i) was induced by caffeine application, intracellular IP3 or Ca2+ liberated by photolysis, it appears that no Mg2+ release mechanism thus exists that is mediated via the action of Ca2+ on membrane-bound receptors in the ER or via the offloading of Mg2+ from binding sites as a result of the increased [Ca2+](i). FCCP treatment for 2 min did not alter the intracellular ATP content, indicating that Mg2+ was not released from Mg-ATP, at least in the first 2 min following exposure to FCCP. FCCP-induced [Mg2+](i) increase was observed at mitochondria localized area, and vice versa. These results suggest that the mitochondria serve as the intracellular Mg2+ store in PC12 cell. Simultaneous measurements of [Ca2+](i) and mitochondrial membrane potential, and also of [Ca2+](i) and [Mg2+](i), revealed that the initial rise in [Mg2+](i) followed that of mitochondrial depolarization for several seconds. These findings show that the source of Mg2+ in the FCCP-induced [Mg2+](i) increase in PC12 cells is mitochondria, and that mitochondrial depolarization triggers the Mg2+ release. (c) 2004 Elsevier B.V All rights reserved.