Plasminogen activator inhibitor-1 promotes the proliferation and inhibits the apoptosis of pulmonary fibroblasts by Ca(2+) signaling.

Our previous investigation demonstrated that plasminogen activator inhibitor-1 (PAI-1) siRNA ameliorated bleomycin (BLM)-induced rat lung fibrosis. The present study was undertaken to explore the effect and the mechanism of PAI-1 siRNA and plasmid pcDNA on the proliferation and apoptosis of cultured fibroblasts from BLM-induced fibrotic lung tissues. The fibroblasts from BLM-induced fibrotic lung tissue were isolated and transfected using PAI-1 siRNA and plasmid pcDNA-PAI-1. The techniques of real time RT-PCR and/or western blot were used to determine the expression of PAI-1, α-smooth muscle actin (α-SMA) (real time RT-PCR only), collagen type-1 and type-3 (real time RT-PCR only), and the levels of caspase-3, ERK and AKT signal molecules. The proliferation of fibroblasts was measured by cell cycle with flow cytometry. The intracellular concentration of Ca(2+) was examined by confocal laser microscopy. PAI-1 siRNA downregulated the PAI-1 mRNA expression by 70%±7% at 24h and protein expression by 73.5%±10% and 42%±3% at 48h and 72h compared to Non-specific siRNA group. Flow cytometry showed that the fibroblasts at the G(2)M+S phase were significantly reduced by 20.56±1.03% after transfecting PAI-1 siRNA and were significantly increased by 43.8±1.21% after transfecting plasmid pcDNA-PAI-1. The mRNA expressions of α-SMA, collagen type-1and type-3 were downregulated after transfecting the PAI-1 siRNA, while upregulated after the transfection of pcDNA-PAI-1. PAI-1 siRNA increased the level of caspase-3, inhibited the expressions of p-ERK and p-AKT protein molecules, while the pcDNA-PAI-1 transfection showed a reversal effect on these expressions. Intracellular Ca(2+) concentration was decreased after transfecting PAI-1 siRNA, whereas increased after transfecting pcDNA-PAI-1. PAI-1 promotes the proliferation, transforming into myofibroblasts, collagen synthesis, and inhibits apoptosis of pulmonary fibroblasts by activating Ca(2+), ERK and AKT signaling pathway. Decreasing PAI-1 expression is an available strategy in inhibiting the progression of pulmonary fibrosis.

Zhang YP ，Wang WL ，Liu J ，Li WB ，Bai LL ，Yuan YD ，Song SX ... -  《-》

siRNA against plasminogen activator inhibitor-1 ameliorates bleomycin-induced lung fibrosis in rats.

Zhang YP ，Li WB ，Wang WL ，Liu J ，Song SX ，Bai LL ，Hu YY ，Yuan YD ，Zhang M ... -  《-》

Inhibition of plasminogen activator inhibitor-1 expression by siRNA in rat hepatic stellate cells.

Hu PF ，Zhu YW ，Zhong W ，Chen YX ，Lin Y ，Zhang X ，Yin C ，Yue HY ，Xie WF ... -  《-》

Plasminogen activator inhibitor-1 suppresses profibrotic responses in fibroblasts from fibrotic lungs.

Idiopathic pulmonary fibrosis (IPF) is a fatal lung disease characterized by progressive interstitial scarification. A hallmark morphological lesion is the accumulation of myofibroblasts or fibrotic lung fibroblasts (FL-fibroblasts) in areas called fibroblastic foci. We previously demonstrated that the expression of both urokinase-type plasminogen activator (uPA) and the uPA receptor are elevated in FL-fibroblasts from the lungs of patients with IPF. FL-fibroblasts isolated from human IPF lungs and from mice with bleomycin-induced pulmonary fibrosis showed an increased rate of proliferation compared with normal lung fibroblasts (NL-fibroblasts) derived from histologically "normal" lung. Basal expression of plasminogen activator inhibitor-1 (PAI-1) in human and murine FL-fibroblasts was reduced, whereas collagen-I and α-smooth muscle actin were markedly elevated. Conversely, alveolar type II epithelial cells surrounding the fibrotic foci in situ, as well as those isolated from IPF lungs, showed increased activation of caspase-3 and PAI-1 with a parallel reduction in uPA expression. Transduction of an adenovirus PAI-1 cDNA construct (Ad-PAI-1) suppressed expression of uPA and collagen-I and attenuated proliferation in FL-fibroblasts. On the contrary, inhibition of basal PAI-1 in NL-fibroblasts increased collagen-I and α-smooth muscle actin. Fibroblasts isolated from PAI-1-deficient mice without lung injury also showed increased collagen-I and uPA. These changes were associated with increased Akt/phosphatase and tensin homolog proliferation/survival signals in FL-fibroblasts, which were reversed by transduction with Ad-PAI-1. This study defines a new role of PAI-1 in the control of fibroblast activation and expansion and its role in the pathogenesis of fibrosing lung disease and, in particular, IPF.

Marudamuthu AS ，Shetty SK ，Bhandary YP ，Karandashova S ，Thompson M ，Sathish V ，Florova G ，Hogan TB ，Pabelick CM ，Prakash YS ，Tsukasaki Y ，Fu J ，Ikebe M ，Idell S ，Shetty S ... -  《-》

Suppression of plasminogen activator inhibitor-1 by RNA interference attenuates pulmonary fibrosis.

Senoo T ，Hattori N ，Tanimoto T ，Furonaka M ，Ishikawa N ，Fujitaka K ，Haruta Y ，Murai H ，Yokoyama A ，Kohno N ... -  《-》