Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States.
Biomedical Mass Spectrometry Center, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States.
Chem Res Toxicol. 2020 Jul 20;33(7):1969-1979. doi: 10.1021/acs.chemrestox.0c00146. Epub 2020 Jun 29.
Albumin is an abundant protein in the lung lining fluid that forms an interface between lung epithelial cells and the external environment. In the lung, albumin can be targeted for adduction by inhaled acrolein. Acrolein, an α,β-unsaturated aldehyde, reacts with biomolecules via Michael addition at the β-carbon or Schiff base formation at the carbonyl carbon. To gain insight into acrolein's mode of action, we investigated albumin-acrolein reactivity and the consequence of albumin adduction by acrolein on cytotoxicity and transcript changes in NCI-H441 and human airway epithelial cells (HAEC). Albumin protected NCI-H441 cells from acrolein toxicity. In addition, albumin inhibited acrolein-induced increase of transcripts associated with cellular stress response, activating transcription factor 3 (ATF3), and antioxidant response, heme oxygenase 1 (HMOX1) in HAEC cells. Acrolein-adducted albumin itself increased HMOX1 transcripts but not ATF3 transcripts. The HMOX1 transcript increase was inhibited by hydralazine, a carbonyl scavenger, suggesting that the carbonyl group of acrolein-adducted albumin mediated HMOX1 transcript increase. In acutely exposed C57BL/6J mice, bronchoalveolar lavage protein carbonylation increased. Acrolein-adducted albumin Cys34 was identified by nLC-MS/MS. These findings indicate that adduction of albumin by acrolein confers a cytoprotective function by scavenging free acrolein, decreasing a cellular stress response, and inducing an antioxidant gene response. Further, these results suggest that β-carbon reactivity may be required for acrolein's cytotoxicity and ATF3 transcript increase, and the carbonyl group of acrolein-adducted albumin can induce HMOX1 transcript increase.
白蛋白是肺衬液中丰富的蛋白质，形成肺上皮细胞与外部环境之间的界面。在肺部，白蛋白可以被吸入的丙烯醛加合。丙烯醛是一种α,β-不饱和醛，通过β-碳上的迈克尔加成或羰基碳上的席夫碱形成与生物分子反应。为了深入了解丙烯醛的作用模式，我们研究了白蛋白-丙烯醛的反应性以及丙烯醛对 NCI-H441 和人气道上皮细胞 (HAEC) 中白蛋白的加合作用对细胞毒性和转录变化的影响。白蛋白保护 NCI-H441 细胞免受丙烯醛毒性。此外，白蛋白抑制了丙烯醛诱导的 HAEC 细胞中与细胞应激反应、激活转录因子 3 (ATF3) 和抗氧化反应、血红素加氧酶 1 (HMOX1) 相关的转录物增加。丙烯醛加合白蛋白本身增加了 HMOX1 的转录物，但不增加 ATF3 的转录物。羰基清除剂肼抑制了 HMOX1 转录物的增加，这表明丙烯醛加合白蛋白的羰基基团介导了 HMOX1 转录物的增加。在急性暴露的 C57BL/6J 小鼠中，支气管肺泡灌洗液蛋白羰基化增加。通过 nLC-MS/MS 鉴定出丙烯醛加合白蛋白 Cys34。这些发现表明，丙烯醛对白蛋白的加合赋予了其细胞保护功能，通过清除游离丙烯醛、减少细胞应激反应和诱导抗氧化基因反应。此外，这些结果表明β-碳的反应性可能是丙烯醛的细胞毒性和 ATF3 转录物增加所必需的，丙烯醛加合白蛋白的羰基基团可以诱导 HMOX1 转录物的增加。
