title: Gene expression in rat lungs during early response to paraquat-induced oxidative stress.
abstract: Paraquat (PQ) is a well-known pneumotoxicant and provides an established model of oxidative stress. This study focused on the transcriptional response to PQ-driven oxidative stress in rat lungs during an early phase post-injection. Rats were sacrificed at 3 h and 24 h after PQ injection (i.p., 20 mg/kg b.w.), and at 3 h after a second injection (i.p., 20 mg/kg b.w.). The left lungs were rapidly excised and used immediately for RNA preparation. The lung tissues did not show any pathological damage microscopically. Differential expression of RNAs in the lung at 3 h was investigated using a DNA array system. Fifteen genes showed a >1.7-fold change in expression level, which was confirmed by real-time PCR. Five genes related to oxidative stress, TRX, HO-1, GST-Yc, NQO-1, and RL/IF-1, and one gene, CLK3, whose function is unknown, showed a significant increase in their expression due to PQ injection. Two genes, HO-1 and NQO-1, that showed 3- and 2-fold increases at 3-h post-injection, were localized by immunohistochemistry. HO-1 was expressed in the bronchial epithelial cells, some type II cells and macrophages of control lungs, and the cells, especially the bronchial epithelial cells, were strongly stained 3 h following PQ treatment. Immunohistochemical analysis of NQO-1 also showed an increase in positive staining in the bronchial epithelial cells of PQ-treated lung sections. The expression of CYP2C6, 2C7, and 2C12, which are specific to or dominant in female liver, decreased markedly, while the male-specific CYP2C13 and 2C11 showed an increase or no effect. Further investigation is needed to clarify the role of these CYP2C family genes on the early phase of PQ toxicity. These results indicate that the acclimation to oxidative stress is already a highly complex process at the onset of PQ-induced damage and that the genes described herein may prove to be major contributors to the subsequent pulmonary fibrosis.
authors.affiliation: Department of Medical Toxicology, Kawasaki Medical School, Kurashiki 701-0192, Japan. tomita@bcc.kawasaki-m.ac.jp
authors.forename: Masafumi
authors.initials: M
authors.lastname: Tomita
authors.forename: Toshiko
authors.initials: T
authors.lastname: Okuyama
authors.forename: Hironobu
authors.initials: H
authors.lastname: Katsuyama
authors.forename: Kazuo
authors.initials: K
authors.lastname: Hidaka
authors.forename: Takemi
authors.initials: T
authors.lastname: Otsuki
authors.forename: Takaki
authors.initials: T
authors.lastname: Ishikawa
mesh_terms: D000818:Animals; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D020869:Gene Expression Profiling; D005982:Glutathione Transferase / Q000235:genetics / Q000378:metabolism; D051547:Heme Oxygenase-1 / Q000235:genetics / Q000378:metabolism; D006540:Herbicides / Q000494:pharmacology*; D020672:I-kappa B Proteins; D008168:Lung / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D008297:Male; D008969:Molecular Sequence Data; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000235:genetics / Q000378:metabolism; D000072000:NF-KappaB Inhibitor alpha; D020411:Oligonucleotide Array Sequence Analysis; D018384:Oxidative Stress / Q000187:drug effects*; D010269:Paraquat / Q000494:pharmacology*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism; D011897:Random Allocation; D051381:Rats; D013879:Thioredoxins / Q000235:genetics / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D006540:Herbicides; D020672:I-kappa B Proteins; C000606204:NFKBIA protein, human; C000606206:Nfkbia protein, rat; D021122:Protein Subunits; C400322:cytochrome P-450 CYP2C subfamily; D000072000:NF-KappaB Inhibitor alpha; D013879:Thioredoxins; D003577:Cytochrome P-450 Enzyme System; D051547:Heme Oxygenase-1; D016660:NAD(P)H Dehydrogenase (Quinone); C447479:NQO1 protein, human; D005982:Glutathione Transferase; C066780:Clk dual-specificity kinases; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D010269:Paraquat