Modulation of intracellular Ca2+ concentration by vitamin B12 in rat thymocytes
Modulation of intracellular Ca2+ concentration by vitamin B12 in rat thymocytes
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DOI：
10.1006/bcmd.2001.0450
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发表时间：
2001-09-01
影响因子：
2.3
通讯作者：
Carpenter, DO
中科院分区：
文献类型：
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作者：
Sukocheva, OA;Abramov, AY;Carpenter, DO
我们研究了维生素B-12（氰钴胺）对大鼠胸腺细胞内钙稳态的几种新作用。我们使用荧光染料Fura-2测定了不同浓度的维生素B-12对细胞内Ca 2+浓度（[Ca 2 +]（i））和Ca-in（2+）信号传导参数的影响。含Ca 2+培养基中的基础[Ca 2 +]（i）为115 +/-5 nM，但在维生素B-12（10 nM）处理的胸腺细胞中[Ca 2 +]（i）降至60 +/-15 nM（平均值+/-SEM）。[Ca 2 +]（i）的下降伴随着内质网Ca 2+储存的增加，这可能是Ca-ATP酶激活的结果。同时，100 nM-10 mM B-12诱导线粒体中Ca 2+的积累。稍高浓度的B-12（1 - 10 nM）对[Ca2 +]（i）无影响。进一步增加B-12浓度，范围从50 μ M到1 mM，导致胸腺细胞中[Ca 2 +]（i）从基础水平（115 +/-15 nM）升高到200 +/-50 nM，并且这种升高在无Ca 2+培养基中被部分阻断。这种高浓度的维生素B-12通过Ca-ATP酶抑制引起内质网Ca 2+储存的逐渐减少。加入内质网Ca 2 +-ATP酶抑制剂2 '，5'-二（叔丁基）-1，4-苯并氢醌（BHQ）、伴刀豆球蛋白A或花生四烯酸诱导细胞内Ca 2+储备耗尽后，未观察到B-12诱导的[Ca 2 +]（i）增加。这些研究表明，在不同的B-12浓度下，维生素B-12通过几种不同的机制调节[Ca 2 +]（i）。G蛋白和钙调素活性参与B-12介导的[Ca 2 +]（i）增加进行了讨论。(C)北京：科学出版社.
We have studied several novel effects of vitamin B-12 (cyanocobalamin) on cellular Ca2+ homeostasis in rat thymocytes. We determined the effect of various concentrations of vitamin B-12 on intracellular Ca2+ concentration ([Ca2+](i)) and parameters of Ca-in(2+) signaling using the fluorescent dye Fura-2. The basal [Ca2+](i) in Ca2+-containing media was 115 +/- 5 nM but in vitamin B-12 (10 nM)-treated thymocytes [Ca2+](i) was decreased to 60 +/- 15 nM (mean +/- SEM) during the first 5 min. The decline in [Ca2+](i) was accompanied by an increase in the endoplasmic reticulum Ca2+ store, presumably as a result of Ca-ATPase activation. At the same time 100 nM-10 mM B-12 induced the accumulation of Ca2+ in mitochondria. Somewhat higher concentrations of B-12 (1-10 nM) had no effect on [Ca2+](i). A further increase in B-12 concentration with range from 50 muM to 1 mM caused a dose-dependent elevation of [Ca2+](i) from the basal level (115 +/- 15 nM) up to 200 +/- 50 nM in thymocytes, and this elevation was partially blocked in Ca2+-free media. This high concentration of vitamin B-12 caused a gradual decrease of endoplasmic reticulum Ca2+ stores by means of Ca-ATPase inhibition. The B-12-induced increase in [Ca2+](i) was not observed after depletion of intracellular Ca2+ stores, induced by addition of 2',5'-di(tert-butyl)-1,4-benzohydroquinone (BHQ), an inhibitor of endoplasmic reticulum Ca2+-ATPase, concanavalin A, or arachidonic acid. These studies show that vitamin B-12 regulates [Ca2+](i) via several different mechanisms at different B-12 concentrations. Participation of G proteins and calmodulin activity in B-12-mediated [Ca2+](i) increase is discussed. (C) 2001 Academic Press.