Guo Qing, Li Shiyu, Xie Yajie, Zhang Qian, Liu Mengge, Xu Zhenrui, Sun Hanxiao, Yang Yan
Institute of Genomic Medicine, College of Pharmacy, Jinan University, Guangzhou 510632, China.
Institute of Genetic Engineering, Southern Medical University, Guangzhou 510515, China.
Free Radic Biol Med. 2017 Jul;108:929-939. doi: 10.1016/j.freeradbiomed.2017.05.012. Epub 2017 May 12.
Silent information regulator 2 (Sir2) enzymes which catalyze NAD+-dependent protein/histone deacetylation. The mammalian sirtuin family SIRT1, SIRT2, SIRT3 and SIRT6 can regulate oxidative stress. The probiotics (Bifidobacterium longum(B.longum) and Lactobacillus acidophilus(L. acidophilus)) have Sir2 gene family and have antioxidant activity in human body. it remains unknown whether probiotics Sir2 has a direct role in regulating oxidative stress. To this end, we knockout BL-sir2(sir2 B. longum) and LA-sir2(sir2 L.acidophilus) in low oxygen level. The antioxidant activities of two sir2 deficient strains was decreased, while when reintroduction of BL-sir2 and LA-sir2, the antioxidant activities were recoveried. In order to understand the regulation mechanism of probiotics Sir2 oxidation response. Then, we screened 65 acetylated protein, and found that SigH (σ) was a substrate of BL-Sir2. In addition, the acetylation level of σ decreased with the increase of BL-Sir2 level in B. longum. Thus, BL-Sir2 deacetylated σ in response to oxidative stress. Next, we transfected BL-Sir2 into HO-induced oxidative damage of 293T cells, BL-Sir2 increased the activity of manganese superoxide dismutase (MnSOD/SOD2) and catalase (CAT) and reduced reactive oxygen species(ROS). Then, we analyzed the differential gene by RNA sequencing and Gene ontology (GO) and found that BL-Sir2 regulated forkhead transcription factor (FOXO3a) mediated antioxidant genes in overexpressed BL-Sir2 HEK293T cells. Our study is the first to link probiotics Sir2 with oxidative stress and uncover the antioxidant mechanism of BL-Sir2 in B. longum itself and human body.
沉默信息调节因子2（Sir2）酶催化依赖烟酰胺腺嘌呤二核苷酸（NAD+）的蛋白质/组蛋白去乙酰化。哺乳动物的sirtuin家族SIRT1、SIRT2、SIRT3和SIRT6可调节氧化应激。益生菌（长双歧杆菌和嗜酸乳杆菌）具有Sir2基因家族，并在人体中具有抗氧化活性。益生菌Sir2是否在调节氧化应激中起直接作用尚不清楚。为此，我们在低氧水平下敲除了长双歧杆菌中的BL-sir2和嗜酸乳杆菌中的LA-sir2。两种sir2缺陷菌株的抗氧化活性降低，而重新导入BL-sir2和LA-sir2后，抗氧化活性得以恢复。为了了解益生菌Sir2氧化反应的调控机制。然后，我们筛选了65种乙酰化蛋白，发现SigH（σ）是BL-Sir2的底物。此外，在长双歧杆菌中，σ的乙酰化水平随BL-Sir2水平的增加而降低。因此，BL-Sir2在氧化应激反应中使σ去乙酰化。接下来，我们将BL-Sir2转染到过氧化氢（HO）诱导的293T细胞氧化损伤模型中，BL-Sir2增加了锰超氧化物歧化酶（MnSOD/SOD2）和过氧化氢酶（CAT）的活性，并降低了活性氧（ROS）水平。然后，我们通过RNA测序和基因本体论（GO）分析差异基因，发现在过表达BL-Sir2的人胚肾293T（HEK293T）细胞中，BL-Sir2调节叉头转录因子（FOXO3a）介导的抗氧化基因。我们的研究首次将益生菌Sir2与氧化应激联系起来，并揭示了长双歧杆菌自身及人体中BL-Sir2的抗氧化机制。
