Cytosolic calcium homeostasis in bovine parathyroid cells and its modulation by protein kinase C.
Cytosolic calcium homeostasis in bovine parathyroid cells and its modulation by protein kinase C.
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牛甲状旁腺细胞胞质钙稳态及其蛋白激酶 C 的调节。
DOI：
10.1113/jphysiol.1993.sp019764
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
Nemeth,EF
中科院分区：
文献类型：
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作者：
Racke,FK;Nemeth,EF
1. 研究了蛋白激酶 C (PKC) 激活剂和抑制剂对负载 fura-2 的离解牛甲状旁腺细胞中胞质 Ca2+ 稳态调节机制的影响。 2. 细胞外 Ca2+ 浓度逐步增加（从 0.5 至 2 或 3 mM）会导致细胞内游离 Ca2+ ([Ca2+]i) 浓度短暂增加，然后持续增加。胞质 Ca2+ 瞬变反映了细胞内 Ca2+ 的动员和细胞外 Ca2+ 的流入，而 [Ca2+]i 的持续增加是由于细胞外 Ca2+ 的流入造成的。用佛波醇肉豆蔻酸酯乙酸酯 (PMA) 进行短暂（1-2 分钟）预处理，可将细胞外 Ca(2+) 诱导的胞质 Ca2+ 瞬变的浓度响应曲线向右移动，而不影响最大响应。细胞外 Mg2+ 引起的胞质 Ca2+ 瞬变同样受到 PMA 的影响。 3. PMA 的这些作用被各种其他 PKC 激活剂模仿，其效力顺序为 PMA > 佛波二丁酸酯 > 苔藓抑素 > (‐)indolactam V > mezerein。这些不改变 PKC 活性的化合物的异构体或类似物（4 α-佛波醇和 (+)吲哚内酰胺 V）不会改变 [Ca2+]i。 4.当用Gd3+阻断细胞外Ca2+的流入时，PKC激活剂抑制引起[Ca2+]i的增加。在细胞外 Ca2+ 不存在的情况下，细胞外 Mg2+ 引起的胞质 Ca2+ 瞬变同样受到 PKC 激活剂的抑制。因此，PKC 的激活会抑制细胞外二价阳离子引起的细胞内 Ca2+ 的动员。 5. 细胞外Ca2+浓度的增加导致[3H]肌醇1,4,5-三磷酸（[3H]InsP3）的形成相应增加。 PMA 预处理使细胞外 Ca(2+) 诱导的 [3H]InsP3 形成的浓度-反应曲线向右移动，而不影响最大反应。 6. PKC 激活剂还对细胞外 Ca2+ 引起的 [Ca2+]i 稳态增加造成一定程度的抑制。相反，PMA 不影响离子霉素或毒胡萝卜素引起的 [Ca2+]i 增加。 7. Ba2+ 用于监测二价阳离子流入。 PMA 降低了细胞外 Ba2+ 引起的荧光信号的上升速率。 8. PKC 激活剂对 [Ca2+]i 的所有这些作用均被星形孢菌素阻断或逆转，其浓度（30-100 nM）可抑制甲状旁腺细胞中的 PKC 活性。单独星形孢菌素可增强由次最大浓度的细胞外二价阳离子引起的胞质 Ca2+ 反应。 9. 因此，PKC 抑制甲状旁腺细胞中细胞内 Ca2+ 的动员和细胞外 Ca2+ 的流入。对 [Ca2+]i 的影响为甲状旁腺细胞表面存在 Ca2+ 受体提供了证据，该受体使用一些其他 Ca(2+) 动员受体常见的跨膜信号传导机制。（摘要截断为 400 字）
1. The effects of protein kinase C (PKC) activators and inhibitors on the mechanisms regulating cytosolic Ca2+ homeostasis in dissociated bovine parathyroid cells loaded with fura‐2 were examined. 2. Stepwise increases in the concentration of extracellular Ca2+ (from 0.5 to 2 or 3 mM) elicited transient followed by sustained increases in the concentration of intracellular free Ca2+ ([Ca2+]i). Cytosolic Ca2+ transients reflected the mobilization of intracellular Ca2+ and influx of extracellular Ca2+ whereas sustained increases in [Ca2+]i resulted from the influx of extracellular Ca2+. Brief (1‐2 min) pretreatment with phorbol myristate acetate (PMA) shifted the concentration‐response curve for extracellular Ca(2+)‐induced cytosolic Ca2+ transients to the right without affecting the maximal response. Cytosolic Ca2+ transients elicited by extracellular Mg2+ were similarly affected by PMA. 3. These effects of PMA were mimicked by various other activators of PKC with the rank order of potency PMA > phorbol dibutyrate > bryostatin , > (‐)indolactam V > mezerein. Isomers or analogues of these compounds that do not alter PKC activity (4 alpha‐phorbols and (+)indolactam V) did not alter [Ca2+]i. 4. PKC activators depressed evoked increases in [Ca2+]i when influx of extracellular Ca2+ was blocked with Gd3+. Cytosolic Ca2+ transients elicited by extracellular Mg2+ in the absence of extracellular Ca2+ were similarly inhibited by PKC activators. Activation of PKC thus inhibits the mobilization of intracellular Ca2+ elicited by extracellular divalent cations. 5. Increases in the concentration of extracellular Ca2+ caused corresponding increases in the formation of [3H]inositol 1,4,5‐trisphosphate ([3H]InsP3). Pretreatment with PMA shifted the concentration‐response curve for extracellular Ca(2+)‐induced [3H]InsP3 formation to the right without affecting the maximal response. 6. PKC activators also caused some depression of steady‐state increases in [Ca2+]i elicited by extracellular Ca2+. In contrast, PMA did not affect increases in [Ca2+]i elicited by ionomycin or thapsigargin. 7. Ba2+ was used to monitor divalent cation influx. PMA decreased the rate of rise of the fluorescent signal elicited by extracellular Ba2+. 8. All these effects of PKC activators on [Ca2+]i were blocked or reversed by staurosporine at concentrations (30‐100 nM) that inhibited PKC activity in parathyroid cells. Staurosporine alone potentiated cytosolic Ca2+ responses evoked by submaximal concentrations of extracellular divalent cations. 9. PKC thus depresses both the mobilization of intracellular Ca2+ and the influx of extracellular Ca2+ in parathyroid cells. The effects on [Ca2+]i provide evidence for a Ca2+ receptor on the surface of parathyroid cells that uses transmembrane signalling mechanisms common to some other Ca(2+)‐mobilizing receptors.(ABSTRACT TRUNCATED AT 400 WORDS)