Li Baojie, Ishii Tetsuro, Tan Choon Ping, Soh Jae-Won, Goff Stephen P
Department of Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, Columbia University, College of Physicians and Surgeons, New York, New York 10032, USA.
J Biol Chem. 2002 Apr 5;277(14):12418-22. doi: 10.1074/jbc.M111443200. Epub 2002 Jan 16.
Peroxiredoxin I (Prx I) is an oxidative stress-inducible antioxidant protein with thioredoxin peroxidase activity. Here we report that the levels of Prx I mRNA and protein are dramatically increased in a murine osteoblast cell line, MC3T3-E1, by treatment with sodium arsenate. We further studied the signaling pathways that control the induction of Prx I expression. The treatment of osteoblasts with arsenate activated ERK1/2, JNK, and p38 MAPK. Pre-treating cells with inhibitors of p38 MAPK abolished the induction of Prx I protein but had minimal effect on the induction of Prx I mRNA, suggesting that p38 MAPK activity was required for post-transcriptional regulation. The inhibition of ERK1 and ERK2 had no effect on the induction of Prx I expression. Furthermore, rottlerin, an inhibitor of protein kinase Cdelta (PKCdelta) and calmodulin kinase III, abrogated the up-regulation at both protein and mRNA levels. Staurosporine and Go6983, inhibitors for PKC, also inhibited the induction of Prx I, suggesting that protein kinase Cdelta is required for the induction by arsenate. PKCdelta was activated by arsenate treatment by in vitro kinase assays. The inhibition of PKCdelta by rottlerin did not affect the activation of p38 MAPK by arsenate. These results suggest that there are two separate signaling pathways involved in the up-regulation of Prx I protein in response to arsenate, PKCdelta required for transcriptional activation and p38 MAPK required for post-transcriptional regulation.
过氧化物酶I（Prx I）是一种具有硫氧还蛋白过氧化物酶活性的氧化应激诱导型抗氧化蛋白。在此我们报告，用砷酸钠处理小鼠成骨细胞系MC3T3-E1后，Prx I的mRNA和蛋白水平显著增加。我们进一步研究了控制Prx I表达诱导的信号通路。用砷酸盐处理成骨细胞可激活ERK1/2、JNK和p38丝裂原活化蛋白激酶（MAPK）。用p38 MAPK抑制剂预处理细胞可消除Prx I蛋白的诱导，但对Prx I mRNA的诱导影响最小，这表明p38 MAPK活性是转录后调控所必需的。抑制ERK1和ERK2对Prx I表达的诱导没有影响。此外，蛋白激酶Cδ（PKCδ）和钙调蛋白激酶III的抑制剂rottlerin在蛋白和mRNA水平上都消除了上调。蛋白激酶C（PKC）的抑制剂星形孢菌素和Go6983也抑制了Prx I的诱导，这表明PKCδ是砷酸盐诱导所必需的。通过体外激酶测定发现，砷酸盐处理可激活PKCδ。rottlerin对PKCδ的抑制并不影响砷酸盐对p38 MAPK的激活。这些结果表明，在响应砷酸盐时，Prx I蛋白上调涉及两条独立的信号通路，转录激活需要PKCδ，转录后调控需要p38 MAPK。
