Bleomycin-induced nuclear factor-kappaB activation in human bronchial epithelial cells involves the phosphorylation of glycogen synthase kinase 3beta.
Nuclear factor-kappaB (NF-kappaB) plays a central role in the development of bleomycin (BLM) lung toxicity, but the regulatory mechanisms are still unknown. In the present study, we investigated the cytotoxic effect of BLM on cultured human bronchial epithelial cells (BECs) and first confirmed that BLM induced the transcriptional activation of NF-kappaB signaling in BECs. We also found that BLM activated Akt (protein kinase B, PKB) and increased the phosphorylation level of glycogen synthase kinase 3beta (GSK3beta). GSK3beta is known to be a key downstream target of Akt, and LY294002, the PI3K (phosphatidylinositol 3-kinase)/Akt inhibitor, which promoted the dephosphorylation of GSK3beta, significantly attenuated BLM-induced NF-kappaB activation. Next, we further observed that constitutively active GSK3beta stabilized the inhibitor of NF-kappaB (IkappaBalpha), inhibited p65 nuclear translocation and partially blocked BLM-induced NF-kappaB activation. Importantly, a co-immunoprecipitation assay revealed that GSK3beta formed a complex with IkappaBalpha, while GSK3beta phosphorylation caused by BLM led to their dissociation. These results suggest that BLM can induce the activation of NF-kappaB signaling in BECs and this process is tightly associated with the phosphorylation status of GSK3beta, implying a possible regulatory mechanism of NF-kappaB signaling in BECs during the toxic lung injury induced by BLM.
Ma
Yan
Y
Institute of Pathology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Key Laboratory of Pulmonary Disease of Ministry of Health of China, Wuhan 430030, PR China.
Wang
Manxiang
M
Li
Naping
N
Wu
Renliang
R
Wang
Xi
X
D000903:Antibiotics, Antineoplastic / Q000633:toxicity*; D001761:Bleomycin / Q000633:toxicity*; D015153:Blotting, Western; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002867:Chromones / Q000494:pharmacology; D004847:Epithelial Cells; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D020672:I-kappa B Proteins / Q000276:immunology; D047468:Immunoprecipitation; D008171:Lung Diseases / Q000139:chemically induced* / Q000201:enzymology / Q000378:metabolism; D009025:Morpholines / Q000494:pharmacology; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects
D000903:Antibiotics, Antineoplastic; D002867:Chromones; D020672:I-kappa B Proteins; D009025:Morpholines; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D047428:Protein Kinase Inhibitors; D001761:Bleomycin; D000072000:NF-KappaB Inhibitor alpha; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; D051057:Proto-Oncogene Proteins c-akt; D038362:Glycogen Synthase Kinase 3