Transforming growth factor-beta1 stimulates heme oxygenase-1 expression via the PI3K/Akt and NF-kappaB pathways in human lung epithelial cells.
A previous report showed that transforming growth factor-beta1 (TGF-beta1) can induce heme oxygenase-1 (HO-1) expression, attenuate cellular injury, and maintain tissue homeostasis. In this study, we investigated the involvement of phosphoinositide-3-OH-kinase (PI3K)/Akt and the nuclear factor-kappaB (NF-kappaB) signaling pathway in TGF-beta1-induced HO-1 expression in human lung epithelial cells (A549). Treatment of A549 cells with TGF-beta1 caused HO-1 to be expressed in a concentration- and time-dependent manner. Treatment of A549 cells with LY 294002 (2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one, a PI3K inhibitor), an Akt inhibitor, and the dominant negative mutant of Akt (Akt DN) inhibited TGF-beta1-induced HO-1 expression and HO-1-luciferase activity. Stimulation of cells with TGF-beta1 caused an increase in Akt phosphorylation in a time-dependent manner, which was inhibited by wortmannin and LY 294002 (PI3K inhibitors). In addition, treatment of A549 cells with Bay 117082 ((E)-3-[4-methylphenylsulfonyl]-2-propenenitrile, an IkappaB phosphorylation inhibitor), pyrrolidine dithiocarbamate (PDTC, an NF-kappaB inhibitor), and the dominant negative mutant of IkappaBalpha (IkappaBalphaM) inhibited TGF-beta1-induced HO-1 expression and HO-1-luciferase activity. Treatment of A549 cells with TGF-beta1-induced IkappaB kinase alpha/beta (IKKalpha/beta) phosphorylation, IkappaBalpha phosphorylation, IkappaBalpha degradation, p65 Ser536 phosphorylation, and kappaB-luciferase activity. The TGF-beta1-mediated increases in IKKalpha/beta phosphorylation, p65 Ser536 phosphorylation, and kappaB-luciferase activity were inhibited by LY 294002, an Akt inhibitor, and Akt DN. Taken together, these results suggest that the PI3K/Akt dependent IKKalpha/beta/NF-kappaB signaling pathway plays an important role in TGF-beta1-induced HO-1 expression in A549 cells.
Lin
Chen-Chun
CC
Department of Chest Medicine, Shin Kong Wu Ho-Su Memorial Hospital, Taiwan.
Chiang
Ling-Ling
LL
Lin
Chien-Huang
CH
Shih
Chung-Hung
CH
Liao
Yi-Ting
YT
Hsu
Ming-Jen
MJ
Chen
Bing-Chang
BC
D002478:Cells, Cultured; D004847:Epithelial Cells / Q000187:drug effects / Q000201:enzymology; D051547:Heme Oxygenase-1 / Q000032:analysis* / Q000096:biosynthesis; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism; D008168:Lung / Q000187:drug effects* / Q000201:enzymology; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000502:physiology*; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology*; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*; D051996:Transcription Factor RelA / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology*
D020672:I-kappa B Proteins; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D051996:Transcription Factor RelA; D053773:Transforming Growth Factor beta1; D000072000:NF-KappaB Inhibitor alpha; D051547:Heme Oxygenase-1; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt