Immediate early gene expression in PC12 cells exposed to lead: requirement for protein kinase C.
Immediate early gene expression in PC12 cells exposed to lead: requirement for protein kinase C.
复制标题
暴露于铅的 PC12 细胞中立即早期基因表达：对蛋白激酶 C 的需求。
DOI：
10.1046/j.1471-4159.2000.741140.x
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发表时间：
2000
影响因子：
4.7
通讯作者：
Bressler,JP
中科院分区：
文献类型：
--
作者：
Kim,KA;Chakraborti,T;Goldstein,GW;Bressler,JP
我们先前证明了暴露于铅的PC 12细胞中c‐fosmRNA的诱导依赖于新的转录。在目前的工作中，我们研究了两种被铅激活的信号转导机制，并已被证明介导c-fosmRNA的诱导。一种机制涉及蛋白激酶C，另一种机制需要钙调蛋白依赖性蛋白激酶II。在暴露于铅或佛波醇12-肉豆蔻酸酯13-乙酸酯的PC 12细胞中，观察到c-fos、c-jun和degr-1 mRNA水平显著增加，但NGFIB mRNA水平没有显著增加。相比之下，56 mM K+去极化的PC 12细胞显示c-fos、c-jun-1和NGFIB增加，但c-jun mRNA没有增加。与其他蛋白激酶C激活剂类似，铅增加AP-1和Egr-1 DNA结合活性。此外，铅增加了用AP-1荧光素酶报告基因构建体转染的小脑颗粒细胞中的荧光素酶活性。铅不会增加PC 12细胞中的c-fosmRNA，这些细胞通过用佛波醇12，13-二丁酸酯处理24小时或与蛋白激酶C抑制剂H-7孵育而耗尽蛋白激酶C。相反，钙调蛋白依赖性蛋白激酶抑制剂KN-62和钙调蛋白抑制剂W-7不能阻断铅对c-fosmRNA的诱导。在暴露于铅的PC 12细胞的核提取物中观察到血清反应元件DNA结合活性增加。有趣的是，铅激活蛋白激酶C亚型δ和ε，但不激活亚型α和β。总之，铅似乎通过一种需要蛋白激酶C的机制诱导即刻早期基因的表达。
We previously demonstrated induction of c‐fosmRNA in PC12 cells exposed to lead that was dependent on new transcription. In the current work, we examined two signal transduction mechanisms that are activated by lead and have been shown to mediate induction of c‐fosmRNA. One mechanism involves protein kinase C, and the other requires calmodulin‐dependent protein kinase II. Significant increases in the levels of c‐fos, c‐jun, andegr‐1 but notNGFIBmRNA were observed in PC12 cells exposed to lead or phorbol 12‐myristate 13‐acetate. In contrast, PC12 cells depolarized with 56 mM K+ displayed an increase in c‐fos,egr‐1, andNGFIBbut not c‐junmRNA. Similar to other activators of protein kinase C, lead increased AP‐1 and Egr‐1 DNA binding activity. Additionally, lead increased luciferase activity in cerebellar granule cells transfected with an AP‐1 luciferase reporter construct. Lead did not increase c‐fosmRNA in PC12 cells that were depleted of protein kinase C by a 24‐h treatment with phorbol 12,13‐dibutyrate or incubated with the protein kinase C inhibitor H‐7. In contrast, an inhibitor of calmodulin‐dependent protein kinase, KN‐62, and an inhibitor of calmodulin, W‐7, did not block the induction of c‐fosmRNA by lead. An increase in serum‐response element DNA‐binding activity was observed in nuclear extracts from PC12 cells exposed to lead. It is interesting that lead activated protein kinase C isoforms δ and ε , but not isoforms αand β. In conclusion, lead appears to induce the expression of immediate early genes by a mechanism that requires protein kinase C.