title: Protein oxidation and degradation caused by particulate matter.
abstract: Particulate matter (PM) modulates the expression of autophagy; however, the role of selective autophagy by PM remains unclear. The objective of this study was to determine the underlying mechanisms in protein oxidation and degradation caused by PM. Human epithelial A549 cells were exposed to diesel exhaust particles (DEPs), urban dust (UD), and carbon black (CB; control particles). Cell survival and proliferation were significantly reduced by DEPs and UD in A549 cells. First, benzo(a)pyrene diolepoxide (BPDE) protein adduct was caused by DEPs at 150 μg/ml. Methionine oxidation (MetO) of human albumin proteins was induced by DEPs, UD, and CB; however, the protein repair mechanism that converts MetO back to methionine by methionine sulfoxide reductases A (MSRA) and B3 (MSRB3) was activated by DEPs and inhibited by UD, suggesting that oxidized protein was accumulating in cells. As to the degradation of oxidized proteins, proteasome and autophagy activation was induced by CB with ubiquitin accumulation, whereas proteasome and autophagy activation was induced by DEPs without ubiquitin accumulation. The results suggest that CB-induced protein degradation may be via an ubiquitin-dependent autophagy pathway, whereas DEP-induced protein degradation may be via an ubiquitin-independent autophagy pathway. A distinct proteotoxic effect may depend on the physicochemistry of PM.
authors.affiliation: School of Public Health, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Ching-Huang
authors.initials: CH
authors.lastname: Lai
authors.affiliation: School of Respiratory Therapy, College of Medicine, Taipei Medical University, Taipei, Taiwan.|Division of Pulmonary Medicine, Department of Internal Medicine, Shuang Ho Hospital, Taipei Medical University, New Taipei City, Taiwan.
authors.forename: Chun-Nin
authors.initials: CN
authors.lastname: Lee
authors.affiliation: School of Respiratory Therapy, College of Medicine, Taipei Medical University, Taipei, Taiwan.|Division of Pulmonary Medicine, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan.
authors.forename: Kuan-Jen
authors.initials: KJ
authors.lastname: Bai
authors.affiliation: School of Respiratory Therapy, College of Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: You-Lan
authors.initials: YL
authors.lastname: Yang
authors.affiliation: Department of Public Health, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.|School of Public Health, College of Public Health and Nutrition, Taipei Medical University, Taipei, Taiwan.
authors.forename: Kai-Jen
authors.initials: KJ
authors.lastname: Chuang
authors.affiliation: Division of Pulmonary Medicine, Department of Internal Medicine, Shuang Ho Hospital, Taipei Medical University, New Taipei City, Taiwan.
authors.forename: Sheng-Ming
authors.initials: SM
authors.lastname: Wu
authors.affiliation: School of Respiratory Therapy, College of Medicine, Taipei Medical University, Taipei, Taiwan.|Division of Pulmonary Medicine, Department of Internal Medicine, Shuang Ho Hospital, Taipei Medical University, New Taipei City, Taiwan.|Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: Hsiao-Chi
authors.initials: HC
authors.lastname: Chuang
mesh_terms: D000072283:A549 Cells; D000418:Albumins / Q000378:metabolism*; D006801:Humans; D051150:Methionine Sulfoxide Reductases / Q000378:metabolism*; D010084:Oxidation-Reduction; D052638:Particulate Matter / Q000633:toxicity*; D059748:Proteolysis / Q000187:drug effects*; D001335:Vehicle Emissions / Q000633:toxicity*
chemical_list: D000418:Albumins; D052638:Particulate Matter; D001335:Vehicle Emissions; D051150:Methionine Sulfoxide Reductases; C027219:methionine sulfoxide reductase; C524352:MSRB3 protein, human