MAPK and JAK-STAT signaling pathways are involved in the oxidative stress-induced decrease in expression of surfactant protein genes.
Oxidative stress is generated by reactive oxygen species (ROS) including hydrogen peroxide (H(2)O(2)), hydroxyl radical (•OH ) and superoxide anion (O(2--)), which are produced as by-products of cellular metabolism. An imbalance in cellular redox status is a potent pathogenic factor that contributes to various chronic inflammatory diseases. In this study, we demonstrate that H(2)O(2 )decreases surfactant protein A, B and ABCA3 mRNA level, and increases SP-D mRNA level in human pulmonary lung epithelial cells. The decreased mRNA level of SP-A and SP-B were significant with a maximum inhibition of 79 and 87%, respectively by 150 µM H(2)O(2 )after 24 hrs of incubation. In addition, ABCA3 mRNA level was decreased with a maximum inhibition of 55% by 150 µM H(2)O(2 )after 12 hrs of incubation. In contrast, 150 µM H(2)O(2 )caused the SP-D mRNA level to increase to 200% of control after 8 hrs of incubation. The H(2)O(2)-induced gene repression or activation of SP-A, SP-B, SP-D and ABCA3 was blocked by pretreatment with the antioxidants N-acetyl-L-cysteine (NAC) and catalase. Furthermore, the inhibition of SP-A and SP-B was associated with reduced thyroid transcription factor -1 (TTF-1) DNA binding activity, and this reduced TTF-1 binding activity may be due to decreased TTF-1 protein expression level. The analyses of signal transduction pathways that may play a role in the regulation of gene expression by H(2)O(2 )using several specific inhibitors showed that U0126, an inhibitor of ERK1/2 upstream kinase MEK1/2, blocked both H(2)O(2)-induced inhibition of SP-A and SP-B gene expression, whereas SB203580, an inhibitor of p38 MAPK, partially blocked H(2)O(2)-mediated inhibition of SP-A gene expression but not SP-B expression. In contrast, AG-490, a specific inhibitor of JAK-STAT pathway, blocked H(2)O(2)-mediated inhibition of SP-B gene expression but not SP-A expression. Immunoblot analyses using specific phosphor-antibodies demonstrated that ERK1/2, p38 MAPK and STAT3 are phosphorylated by oxidative stress suggesting that H(2)O(2)-induced inhibition of SP-A and SP-B gene expression is associated with MAPK and JAKSTAT signaling pathway. These data, therefore, suggest that H(2)O(2 )affects SP-A and SP-B gene regulation by reducing TTF-1 DNA binding activity via MAPKs or STAT signaling pathways.
Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI 53201, USA.
Sang-Kyu
SK
Park
Mary K
MK
Dahmer
Michael W
MW
Quasney
D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism; D000111:Acetylcysteine / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology; D002070:Butadienes / Q000494:pharmacology; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D053612:Janus Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009570:Nitriles / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D037662:Pulmonary Surfactant-Associated Protein A / Q000235:genetics / Q000378:metabolism; D037701:Pulmonary Surfactant-Associated Protein B / Q000235:genetics / Q000378:metabolism; D037663:Pulmonary Surfactant-Associated Protein D / Q000235:genetics / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D050796:STAT3 Transcription Factor / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D014157:Transcription Factors; D020032:Tyrphostins / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
C441524:ABCA3 protein, human; D018528:ATP-Binding Cassette Transporters; D000975:Antioxidants; D002070:Butadienes; D004268:DNA-Binding Proteins; D007093:Imidazoles; D009570:Nitriles; D037662:Pulmonary Surfactant-Associated Protein A; D037701:Pulmonary Surfactant-Associated Protein B; D037663:Pulmonary Surfactant-Associated Protein D; D011725:Pyridines; D012333:RNA, Messenger; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; C504003:TTF1 protein, human; D014157:Transcription Factors; D020032:Tyrphostins; C113580:U 0126; C095512:alpha-cyano-(3,4-dihydroxy)-N-benzylcinnamide; D006861:Hydrogen Peroxide; D053612:Janus Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C093642:SB 203580; D000111:Acetylcysteine