The oxidation of methionine (Met) by reactive oxygen species (ROS) causes detrimental effects on the protein functions. Methionine sulfoxide reductase (Msr) is the secondary antioxidant enzyme involved in protein repair, and is divided into two distinct classes, MsrA and MsrB, although the mechanisms underlying the transcriptional regulation of Msrs remain largely unknown. In this study, the full-length cDNAs encoding MsrA and three alternatively spliced isoforms of MsrB were isolated from the red flour beetle, Tribolium castaneum. Exposure of female adults to oxidative, heat and cold stresses induced expressions of both MsrA and MsrB. RNAi-mediated knockdown of MsrA and MsrB resulted in increased sensitivity of T. castaneum to paraquat-induced oxidative stress. Treatment with 20-hydroxyecdysone (20E) increased expression levels of both MsrA and MsrB. Knockdown of transcription factor forkhead box O (FOXO) decreased both MsrA and MsrB mRNA levels and abolished the induction of MsrA and MsrB by paraquat. Luciferase reporter assays revealed that FOXO directly activates the promoters of both MsrA and MsrB. Moreover, paraquat treatment induced expression of two ecdysone biosynthesis genes, Shade and Phantom, 20E upregulated exoression of FOXO, promoted FOXO nuclear translocation，and knockdown of FOXO abolished induction of MsrA and MsrB expression by 20E, suggesting that regulation of MsrA and MsrB by 20E was mediated by FOXO. Overall, these results provide important insights into the transcriptional regulation of insect Msrs.

活性氧 (ROS) 对蛋氨酸 (Met) 的氧化会对蛋白质功能产生不利影响。甲硫氨酸亚砜还原酶 (Msr) 是参与蛋白质修复的二级抗氧化酶，分为两个不同的类别，MsrA 和 MsrB，尽管 Msrs 转录调控的基本机制仍然未知。在这项研究中，从红粉甲虫Tribolium castaneum中分离出编码MsrA和三个可变剪接同种型MsrB的全长 cDNA 。成年女性暴露于氧化性，既诱导表达热和冷压力MSRA和MSRB。RNAi 介导的MsrA和MsrB导致T. castaneum对百草枯引起的氧化应激的敏感性增加。治疗20-羟基（20E）都增加的表达水平MSRA和MSRB。敲低的转录因子叉头框O（FOXO）降低两者MSRA和MSRB mRNA水平和废除的诱导MSRA和MSRB百草枯。荧光素酶报告实验表明，FOXO直接激活这两个发起人MSRA和MSRB。此外，百草枯处理诱导了两种蜕皮激素生物合成基因Shade和幻影，20E上调exoression的FOXO，促进了FOXO核易位，和敲除的FOXO废除的感应MSRA和MSRB表达20E，提示该调节MSRA和MSRB通过20E通过介导FOXO。总的来说，这些结果为昆虫Msrs的转录调控提供了重要的见解。