Specialized distributions of mitochondria and endoplasmic reticulum proteins define Ca2+ wave amplification sites in cultured astrocytes
Specialized distributions of mitochondria and endoplasmic reticulum proteins define Ca2+ wave amplification sites in cultured astrocytes
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线粒体和内质网蛋白的特殊分布定义了培养星形胶质细胞中的 Ca2 波放大位点
DOI：
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发表时间：
1998
影响因子：
4.2
通讯作者：
C. A. Sheppard
中科院分区：
文献类型：
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作者：
P. B. Simpson;Surabhi Mehotra;D. Langley;C. A. Sheppard
本研究旨在检测培养的星形胶质细胞中内质网 (ER) 蛋白钙网蛋白和兰尼碱受体以及线粒体的表达和作用。通过多项研究，我们确定了线粒体在星形胶质细胞 Ca2+ 信号传导中的关键作用：（1）发现再生 Ca2+ 波放大位点（具有高振幅 ER Ca2+ 释放）与线粒体在细胞中的位置之间存在显着相关性； (2) 去甲肾上腺素 (2 μM) 导致 34% 星形胶质细胞线粒体中 rhod 2 荧光快速增加，表明细胞质 Ca2+ 反应导致线粒体 Ca2+ 升高； （3）用质子载体羰基氰化物对（三氟甲氧基）苯腙进行预处理来抑制线粒体活性，显着降低了随后去甲肾上腺素引起的胞质 Ca2+ 反应的幅度。然后，我们通过免疫细胞化学研究了几种 ER 蛋白在 Ca2+ 信号传导中的作用。发现瑞尼定受体和钙网蛋白在星形胶质细胞中以异质模式表达。钙网蛋白的表达模式与线粒体的分布密切相关，而兰尼碱受体的表达与这些细胞因子中的任何一个都不相似。我们测量了单个星形胶质细胞中的 Ca2+ 波动力学，然后通过免疫细胞化学评估了同一细胞中的蛋白质分布。去甲肾上腺素诱发的 Ca2+ 波振幅与钙网蛋白分布之间的互相关表明该 Ca2+ 结合蛋白与再生波放大位点之间存在密切的空间关系。这些结果表明，星形胶质细胞中 Ca2+ 波的放大位点可通过钙网蛋白（和 2 型 InsP3R）的积累以及线粒体的存在来识别，线粒体可能调节 ER Ca2+ 释放过程。 J.神经科学。资源。 52:672–683, 1998。1998 年 Wiley‐Liss, Inc 出版。本文是美国政府的作品，因此在美国属于公共领域。
This study was undertaken to examine the expression and role of the endoplasmic reticulum (ER) proteins calreticulin and ryanodine receptors, and mitochondria, in cultured astrocytes. Using several lines of investigation, we have identified a key role for mitochondria in astrocyte Ca2+ signalling: (1) a significant correlation was found between sites of regenerative Ca2+ wave amplification (possessing high amplitude ER Ca2+ release) and the location of mitochondria in the cell; (2) norepinephrine (2 μM) caused a rapid‐onset increase in rhod 2 fluorescence in 34% of astrocyte mitochondria, indicating that cytosolic Ca2+ responses result in mitochondrial Ca2+ elevation; and (3) pretreatment with the protonophore carbonyl cyanide p‐(trifluoromethoxy)phenylhydrazone to inhibit mitochondrial activity markedly reduced the amplitude of subsequent norepinephrine‐evoked cytosolic Ca2+ responses. We then investigated the roles of several ER proteins in Ca2+ signalling by immunocytochemistry. Ryanodine receptors and calreticulin were found to be expressed in heterogeneous patterns in astrocytes. The expression pattern of calreticulin corresponded closely with the distribution of mitochondria, whereas the expression of ryanodine receptors was not similar to that of either of these cellular factors. We measured Ca2+ wave kinetics in a single astrocyte, then assessed protein distribution by immunocytochemistry in the same cell. Cross‐correlation between norepinephrine‐evoked Ca2+ wave amplitude and calreticulin distribution indicated a close spatial relationship between this Ca2+‐binding protein and sites of regenerative wave amplification. These results demonstrate that amplification sites for Ca2+ waves in astrocytes are identifiable by accumulations of calreticulin (and type 2 InsP3Rs), and by the presence of mitochondria, which may regulate the ER Ca2+ release process. J. Neurosci. Res. 52:672–683, 1998. Published 1998 Wiley‐Liss, Inc. This article is a US Government work and, as such, is in the public domain in the United States of America.