Mechanism of glucocorticoid-induced increase in pancreatic amylase gene transcription.
Mechanism of glucocorticoid-induced increase in pancreatic amylase gene transcription.
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DOI：
10.1016/s0021-9258(18)47795-2
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发表时间：
1987-11
期刊：
影响因子：
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通讯作者：
C. Logsdon;K. Perot;A. McDonald
中科院分区：
文献类型：
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作者：
C. Logsdon;K. Perot;A. McDonald
为了确定糖皮质激素诱导的胰腺腺泡AR 42 J细胞中淀粉酶含量增加的机制，我们检测了地塞米松对淀粉酶蛋白生物合成、稳态mRNA水平和基因转录的影响。地塞米松处理导致淀粉酶合成呈剂量依赖性增加，在2 nM时最大增加一半，在100 nM时最大增加6倍。地塞米松诱导的淀粉酶合成增加在12 h后可检测到，19 h后达到最大值的一半，72 h后接近最大值。地塞米松治疗还增加淀粉酶mRNA水平的时间和剂量依赖性的方式与淀粉酶合成的变化平行。核RNA转录延长（运行）分析表明，淀粉酶基因转录也增加了时间和剂量依赖性的方式。糖皮质激素对淀粉酶基因转录的增强作用相对缓慢，在用100 nM地塞米松处理48小时后增加了6倍。因此，糖皮质激素对胰腺淀粉酶基因转录的影响完全解释了淀粉酶mRNA、合成和含量水平的增加。然而，由于地塞米松诱导淀粉酶基因表达的时间过程缓慢，我们评估了糖皮质激素诱导调节蛋白的可能性。我们发现，包括放线菌酮或嘌呤霉素在地塞米松治疗阻断淀粉酶mRNA的诱导。这些数据表明，糖皮质激素诱导的淀粉酶基因转录的增加需要诱导一种未鉴定的调节蛋白。
To determine the mechanism(s) responsible for glucocorticoid-induced increases in amylase content in pancreatic acinar AR42J cells, we examined the effects of dexamethasone on amylase protein biosynthesis, steady-state mRNA levels, and gene transcription. Dexamethasone treatment led to a dose-dependent increase in amylase synthesis which was one-half maximal at 2 nM and maximal at 100 nM where a 6-fold increase was achieved. This dexamethasone-induced increase in amylase synthesis was detectable after 12 h, one-half maximal after 19 h, and approached maximal after 72 h. Dexamethasone treatment also increased amylase mRNA levels in a time- and dose-dependent manner in parallel with the changes in amylase synthesis. Nuclear RNA transcript elongation (run-on) assays indicated that amylase gene transcription was also increased in a time- and dose-dependent manner. Glucocorticoid enhancement of amylase gene transcription occurred relatively slowly, with a 6-fold increase occurring after 48 h of treatment with 100 nM dexamethasone. Thus, the effects of glucocorticoids on pancreatic amylase gene transcription fully accounted for the increased levels of amylase mRNA, synthesis, and content. However, due to the slow time course of dexamethasone induction of amylase gene expression we evaluated the possibility of glucocorticoid induction of a regulatory protein. We found that inclusion of cycloheximide or puromycin during dexamethasone treatment blocked the induction of amylase mRNA. These data suggest that the glucocorticoid-induced increase in amylase gene transcription requires induction of an unidentified regulatory protein(s).