Sustained Ca2+ transfer across mitochondria is essential for mitochondrial Ca2+ buffering, store-operated Ca2+ entry, and Ca2+ store refilling
Sustained Ca2+ transfer across mitochondria is essential for mitochondrial Ca2+ buffering, store-operated Ca2+ entry, and Ca2+ store refilling
复制标题
DOI：
10.1074/jbc.m302511200
复制
发表时间：
2003-11-07
影响因子：
4.8
通讯作者：
Graier, WF
中科院分区：
文献类型：
--
作者：
Malli, R;Frieden, M;Graier, WF
已经发现线粒体在用肌醇1，4，5-三磷酸生成激动剂刺激细胞期间螯合和释放Ca 2+，从而产生维持容量性Ca 2+进入（CCE）活性的低Ca 2+的质膜下微区。阻止线粒体Ca 2+摄取的程序抑制局部Ca 2+缓冲和CCE，但尚不清楚Ca 2+是否必须通过线粒体转运或仍然被困在线粒体中。因此，我们分析了线粒体Ca 2+外流对线粒体缓冲质膜下Ca 2+、维持CCE和促进内皮细胞内质网（ER）再填充能力的贡献。在添加组胺后，初始的线粒体Ca 2+瞬态，监测与ratio-metric-pericam-线粒体，在很大程度上是独立的细胞外Ca 2+。然而，随后的细胞外Ca 2+的去除产生了可逆的[Ca 2 +]（线粒体）的减少，表明Ca 2+被线粒体持续摄取和释放，虽然[Ca 2 +]（线粒体）已恢复到基础水平。因此，用CGP 37157抑制线粒体Na+/Ca 2+交换增加[Ca 2 +]（mito）并消除线粒体缓冲质膜下Ca 2+的能力，导致BKCa通道活性增加和CCE减少。因此，CGP 37157也可逆地抑制细胞刺激过程中的ER再填充。如果用寡霉素/抗霉素A阻止线粒体Ca 2+摄取，则模拟CGP 37157的这些作用。因此，在细胞刺激期间，通过线粒体的连续Ca 2+通量是线粒体产生低Ca 2+的质膜下微区、促进CCE和将Ca 2+从质膜传递到ER的能力的基础。
Mitochondria have been found to sequester and release Ca2+ during cell stimulation with inositol 1,4,5-triphosphate-generating agonists, thereby generating subplasmalemmal microdomains of low Ca2+ that sustain activity of capacitative Ca2+ entry (CCE). Procedures that prevent mitochondrial Ca2+ uptake inhibit local Ca2+ buffering and CCE, but it is not clear whether Ca2+ has to transit through or remains trapped in the mitochondria. Thus, we analyzed the contribution of mitochondrial Ca2+ efflux on the ability of mitochondria to buffer subplasmalemmal Ca2+, to maintain CCE, and to facilitate endoplasmic reticulum (ER) refilling in endothelial cells. Upon the addition of histamine, the initial mitochondrial Ca2+ transient, monitored with ratio-metric-pericam-mitochondria, was largely independent of extracellular Ca2+. However, subsequent removal of extracellular Ca2+ produced a reversible decrease in [Ca2+](mito), indicating that Ca2+ was continuously taken up and released by mitochondria, although [Ca2+](mito) had returned to basal levels. Accordingly, inhibition of the mitochondrial Na+/Ca2+ exchanger with CGP 37157 increased [Ca2+](mito) and abolished the ability of mitochondria to buffer subplasmalemmal Ca2+, resulting in an increased activity of BKCa channels and a decrease in CCE. Hence, CGP 37157 also reversibly inhibited ER refilling during cell stimulation. These effects of CGP 37157 were mimicked if mitochondrial Ca2+ uptake was prevented with oligomycin/antimycin A. Thus, during cell stimulation a continuous Ca2+ flux through mitochondria underlies the ability of mitochondria to generate subplasmalemmal microdomains of low Ca2+, to facilitate CCE, and to relay Ca2+ from the plasma membrane to the ER.