Bidirectional Ca2+ coupling of mitochondria with the endoplasmic reticulum and regulation of multimodal Ca2+ entries in rat brown adipocytes
Bidirectional Ca2+ coupling of mitochondria with the endoplasmic reticulum and regulation of multimodal Ca2+ entries in rat brown adipocytes
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DOI：
10.1152/ajpcell.00649.2005
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发表时间：
2007-02-01
影响因子：
5.5
通讯作者：
Kuba, Kenji
中科院分区：
文献类型：
--
作者：
Kuba, Masako;Higure, Yoko;Kuba, Kenji
在体外培养的大鼠棕色脂肪细胞中，研究了内质网（ER）和线粒体之间的相互联系及其对质膜Ca ~（2+）内流的调节。荧光法测定细胞质Ca ~（2+）、Mg ~（2+）和线粒体膜电位。细胞质Ca 2+浓度（[Ca 2 +]（i））的持续上升的组成部分，由毒胡萝卜素产生的消除细胞外Ca 2+，通过耗尽细胞外Na+抑制，并通过提高细胞外pH值增强。FCCP，二硝基苯酚，鱼藤酮引起的双相或三相上升[Ca 2 +]（i），其中第一阶段伴随着线粒体去极化。FCCP诱导的第一阶段被寡霉素部分抑制，但不被钌红，环孢素A，U- 73122，无钙EGTA溶液和无Na+溶液抑制。FCCP诱导的平行线粒体复极化第二阶段被去除细胞外Ca 2+部分阻断，并被寡霉素完全阻断，但不被毒胡萝卜素或缺乏Na+的溶液阻断，伴随着细胞质Mg 2+浓度的升高，并与高pH值相结合-诱导的[Ca 2 +]升高（i），而细胞外Ca ~（2+）非依赖性成分则被U- 73122和cyclopiazonic acid阻断。FCCP诱导的第三相可被去除Ca ~（2+）而非毒胡萝卜素阻断，可被降低Na ~+而被抑制，可被升高pH而被增强。FCCP作用后，环匹阿尼酸诱导的无Ca ~（2+）溶液中[Ca ~（2+）]（i）的升高被抑制。因此，线粒体解偶联导致Ca 2+释放，激活Ca 2+从ER释放和钙库操作的Ca 2+进入，并直接激发新的质膜Ca 2+进入，而Ca 2+从ER释放激活Ca 2+在线粒体中的积累或从线粒体释放，表明大鼠棕色脂肪细胞中的双向线粒体- ER偶联。
How the endoplasmic reticulum ( ER) and mitochondria communicate with each other and how they regulate plasmalemmal Ca2+ entry were studied in cultured rat brown adipocytes. Cytoplasmic Ca2+ or Mg2+ and mitochondrial membrane potential were measured by fluorometry. The sustained component of rises in cytoplasmic Ca2+ concentration ([Ca2(+)](i)) produced by thapsigargin was abolished by removing extracellular Ca2+, depressed by depleting extracellular Na+, and enhanced by raising extracellular pH. FCCP, dinitrophenol, and rotenone caused bi- or triphasic rises in [Ca2+](i), in which the first phase was accompanied by mitochondrial depolarization. The FCCP-induced first phase was partially inhibited by oligomycin but not by ruthenium red, cyclosporine A, U- 73122, a Ca2+- free EGTA solution, and an Na+-free solution. The FCCP-induced second phase paralleling mitochondrial repolarization was partially blocked by removing extracellular Ca2+ and fully blocked by oligomycin but not by thapsigargin or an Na+-deficient solution, was accompanied by a rise in cytoplasmic Mg2+ concentration, and was summated with a high pH- induced rise in [Ca2+](i), whereas the extracellular Ca2+-independent component was blocked by U- 73122 and cyclopiazonic acid. The FCCP- induced third phase was blocked by removing Ca2+ but not by thapsigargin, depressed by decreasing Na+, and enhanced by raising pH. Cyclopiazonic acid- evoked rises in [Ca2+](i) in a Ca2+- free solution were depressed after FCCP actions. Thus mitochondrial uncoupling causes Ca2+ release, activating Ca2+ release from the ER and store- operated Ca2+ entry, and directly elicits a novel plasmalemmal Ca2+ entry, whereas Ca2+ release from the ER activates Ca2+ accumulation in, or release from, mitochondria, indicating bidirectional mitochondria- ER couplings in rat brown adipocytes.