Nrf2 In Susceptibility To Hyperoxic Lung Injury

我们已经完成了一个全基因组筛选易感基因的染色体位点，控制高氧诱导的肺损伤的intercross（B6 C3 F2）队列来自易感C57 BL/6 J（B6）和耐药C3 H/HeJ（C3）小鼠。在第2和第3染色体上分别检测到显著和暗示性数量性状位点（QTL）。染色体2 QTL内的候选基因是Nfe 212（核因子，红细胞衍生2，like 2），其编码转录因子NRF 2（NF-E2相关因子2，Nrf 2）。NRF 2已被鉴定为抗氧化反应元件（ARE）介导的解毒酶基因的正调节因子，用于保护细胞免受亲电毒性、氧化应激和致癌性。为了验证Nrf 2是B6和C3小鼠差异易感性的候选基因的假设，我们对两种品系的Nrf 2进行了测序。对B6和C3小鼠中Nrf 2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处具有T到C的取代，与C3相比，预测其在B6小鼠中增加Sp1转录因子结合位点。在B6 C3 F2队列中，该多态性与高氧易感性分离，表明该多态性可能是该模型中高氧肺损伤易感性的重要决定因素。 我们通过将Nrf 2定点突变小鼠（Nrf 2-/-）和野生型小鼠（Nrf 2 +/+）暴露于高氧，验证了Nrf 2有助于肺保护免受高氧损伤的假设。与Nrf 2 +/+小鼠相比，暴露于高氧后，Nrf 2-/-小鼠的肺通透性过高、巨噬细胞炎症和上皮损伤显著更大。与Nrf 2在高氧肺损伤中的保护作用一致，与Nrf 2 +/+小鼠相比，高氧后Nrf 2-/-小鼠中多种抗氧化剂和2期基因的mRNA表达以及抗氧化酶活性显著降低。这些研究已经确定Nrf 2作为一个重要的易感基因在小鼠氧化剂诱导的肺病理学的发病机制，并可能有重要的意义，了解易感人群中的类似过程。

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.