Nrf2 In Susceptibility To Hyperoxic Lung Injury

我们已经完成了对易感C57BL/6J(B6)和耐药C3H/HeJ(C3)小鼠的交叉(B6C3F2)队列中控制高氧诱导肺损伤的易感基因的染色体位置的全基因组筛选。在第2和第3染色体上分别检测到显著和暗示的数量性状基因座。2号染色体QTL中的一个候选基因是NFe2l2(核因子，红系衍生的2，Like 2)，它编码一个转录因子NRF2(核因子-E2相关因子2，NRF2)。NRF2已被确定为抗氧化剂反应元件(ARE)介导的解毒酶基因的正调控因子，用于保护细胞免受电泳性毒性、氧化应激和致癌性的影响。为了验证Nrf2是B6和C3小鼠差异易感性的候选基因的假设，我们对这两个品系的Nrf2进行了测序。对B6和C3小鼠Nrf2启动子的分析揭示了它们之间潜在的重要变异。B6小鼠在-336处有T到C的替换，与C3相比，这被预测在B6小鼠中增加了Sp1转录因子结合位点。在B6C3F2队列中，该多态与高氧易感性分离，提示该多态可能是该模型中高氧性肺损伤易感性的重要决定因素。 我们通过将Nrf2定点突变的小鼠(Nrf2-/-)和野生型(Nrf2+/+)小鼠暴露在高氧中，验证了NRF2有助于保护肺免受高氧损伤的假设。高氧暴露后，Nrf2-/-小鼠的肺高通透性、巨噬细胞炎症和上皮损伤显著高于Nrf2+/+小鼠。与Nrf2在高氧性肺损伤中的保护作用一致，Nrf2-/-小鼠在高氧后多种抗氧化剂和第二阶段基因的mRNA表达以及抗氧化酶活性显著低于Nrf2+/+小鼠。这些研究已经确认Nrf2是氧化诱导小鼠肺病理发病机制中的一个重要易感基因，并可能对了解人类易感人群中类似的过程具有重要意义。

We have completed a genome-wide screen for chromosomal loci of susceptibility genes that control hyperoxia-induced pulmonary injury in an intercross (B6C3F2) cohort derived from susceptible C57BL/6J (B6) and resistant C3H/HeJ (C3) mice. Significant and suggestive quantitative trait loci (QTLs) were identified on chromosomes 2 and 3, respectively. A candidate gene within the chromosome 2 QTL is Nfe2l2 (nuclear factor, erythroid derived 2, like 2), which encodes a transcription factor NRF2 (NF-E2 related factor 2, Nrf2). NRF2 has been identified as an antioxidant response element (ARE)-mediated positive regulator of detoxifying enzymes genes for protecting cells against electrophile toxicity, oxidative stress, and carcinogenicity. To test the hypothesis that Nrf2 is a candidate gene for differential susceptibility in B6 and C3 mice, we sequenced Nrf2 in both strains. Analysis of the Nrf2 promoter in B6 and C3 mice revealed a potentially important variation between them. B6 mice possess a T to C substitution at -336, which is predicted to add a Sp1 transcription factor-binding site in B6 mice compared to C3. The polymorphism segregated with hyperoxia susceptibility in the B6C3F2 cohort, suggesting that the polymorphism is potentially an important determinant of suceptibility to hyperoxic lung injury in this model. We tested the hypothesis that NRF2 contributes to pulmonary protection against hyperoxic injury by exposing mice with site-directed mutation of Nrf2 (Nrf2-/-) and wild type (Nrf2+/+) mice to hyperoxia. Pulmonary hyperpermeability, macrophage inflammation, and epithelial injury were significantly greater in Nrf2-/- mice compared to Nrf2+/+ mice after exposure to hyperoxia. Consistent with a protective role for Nrf2 in hyperoxic lung injury, mRNA expression of multiple antioxidant and phase 2 genes, as well as antioxidant enzyme activities, were significantly lower in Nrf2-/- mice compared to Nrf2+/+ mice after hyperoxia. These studies have identified Nrf2 as an important susceptibility gene in the pathogenesis of oxidant-induced lung pathology in the mouse, and may have important implications for understanding similar processes in susceptible human populations.