Hypoxia-inducible factor-1α mediates TGF-β-induced PAI-1 production in alveolar macrophages in pulmonary fibrosis.
Hypoxia-inducible factor-1α (HIF-1α), a transcription factor that functions as a master regulator of oxygen homeostasis, has been implicated in fibrinogenesis. Here, we explore the role of HIF-1α in transforming growth factor-β (TGF-β) signaling by examining the effects of TGF-β(1) on the expression of plasminogen activator inhibitor-1 (PAI-1). Immunohistochemistry of lung tissue from a mouse bleomycin (BLM)-induced pulmonary fibrosis model revealed that expression of HIF-1α and PAI-1 was predominantly induced in alveolar macrophages. Real-time RT-PCR and ELISA analysis showed that PAI-1 mRNA and activated PAI-1 protein level were strongly induced 7 days after BLM instillation. Stimulation of cultured mouse alveolar macrophages (MH-S cells) with TGF-β(1) induced PAI-1 production, which was associated with HIF-1α protein accumulation. This accumulation of HIF-1α protein was inhibited by SB431542 (type I TGF-β receptor/ALK receptor inhibitor) but not by PD98059 (MEK1 inhibitor) and SB203580 (p38 MAP kinase inhibitor). Expression of prolyl-hydroxylase domain (PHD)-2, which is essential for HIF-1α degradation, was inhibited by TGF-β(1), and this decrease was abolished by SB431542. TGF-β(1) induction of PAI-1 mRNA and its protein expression were significantly attenuated by HIF-1α silencing. Transcriptome analysis by cDNA microarray of MH-S cells after HIF-1α silencing uncovered several pro-fibrotic genes whose regulation by TGF-β(1) required HIF-1α, including platelet-derived growth factor-A. Taken together, these findings expand our concept of the role of HIF-1α in pulmonary fibrosis in mediating the effects of TGF-β(1) on the expression of the pro-fibrotic genes in activated alveolar macrophages.
Department of Medicine and Biological Science, Gunma University Graduate School of Medicine, Maebashi, Japan.
Manabu
M
Ueno
Toshitaka
T
Maeno
Miyuki
M
Nomura
Kana
K
Aoyagi-Ikeda
Hiroki
H
Matsui
Kenichiro
K
Hara
Toru
T
Tanaka
Tatsuya
T
Iso
Tatsuo
T
Suga
Masahiko
M
Kurabayashi
D000818:Animals; D001549:Benzamides / Q000494:pharmacology; D001761:Bleomycin; D015687:Cell Hypoxia / Q000502:physiology; D004149:Dioxoles / Q000494:pharmacology; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000502:physiology*; D016676:Macrophages, Alveolar / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D017395:Plasminogen Activator Inhibitor 1 / Q000096:biosynthesis*; D011658:Pulmonary Fibrosis / Q000139:chemically induced; D016212:Transforming Growth Factor beta / Q000096:biosynthesis / Q000494:pharmacology*
C459179:4-(5-benzo(1,3)dioxol-5-yl-4-pyridin-2-yl-1H-imidazol-2-yl)benzamide; D001549:Benzamides; D004149:Dioxoles; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D017395:Plasminogen Activator Inhibitor 1; D016212:Transforming Growth Factor beta; D001761:Bleomycin