Idiopathic pulmonary fibrosis (IPF) is characterized by progressive fibroblast and myofibroblast proliferation, and extensive deposition of extracellular matrix (ECM). Fibroblast growth factor-1 (FGF-1) belongs to the FGF family and has been shown to inhibit fibroblast collagen production and differentiation into myofibroblasts, and revert epithelial-mesenchymal transition by inhibiting TGF-1 signalling pathways. However, the precise role of FGF-1 in pulmonary fibrosis has not yet been elucidated. In this study, we explore the mechanisms underlying the anti-fibrogenic effect of FGF-1 in pulmonary fibrosis in vitro and in vivo by prolonged transient overexpression of FGF-1 (AdFGF-1) and TGF-1 (AdTGF-1) using adenoviral vectors. In vivo, FGF-1 overexpression markedly attenuated TGF-1-induced pulmonary fibrosis in rat lungs when given both concomitantly, or delayed, by enhancing proliferation and hyperplasia of alveolar epithelial cells (AECs). AdFGF-1 also attenuated the TGF-1 signalling pathway and induced FGFR1 expression in AECs. In vitro, AdFGF-1 prevented the increase in -SMA and the decrease in E-cadherin induced by AdTGF-1 in normal human lung fibroblasts, primary human pulmonary AECs, and A549 cells. Concomitantly, AdTGF-1-induced Smad2 phosphorylation was significantly reduced by AdFGF-1 in both cell types. AdFGF-1 also attenuated the increase in TGFR1 protein and mRNA levels in fibroblasts. In AECs, AdFGF-1 decreased TGFR1 protein by favouring TGFR1 degradation through the caveolin-1/proteasome pathway. Furthermore, FGFR1 expression was increased in AECs, whereas it was decreased in fibroblasts. In serum of IPF patients, FGF-1 levels were increased compared to controls. Interestingly, FGF-1 expression was restricted to areas of AEC hyperplasia, but not -SMA-positive areas in IPF lung tissue. Our results demonstrate that FGF-1 may have preventative and therapeutic effects on TGF-1-driven pulmonary fibrosis via inhibiting myofibroblast differentiation, inducing AEC proliferation, regulating TGF-1 signalling by controlling TGFR1 expression and degradation, and regulating FGFR1 expression. Thus, modulating FGF-1 signalling represents a potential therapy for the treatment of pulmonary fibrosis.

Many DNAzymes have been isolated from synthetic DNA pools to cleave natural RNA (D-RNA) substrates and some have been utilized for the design of aptazyme biosensors for bioanalytical applications. Even though these biosensors perform well in simple sample matrices, they do not function effectively in complex biological samples due to ubiquitous RNases that can efficiently cleave D-RNA substrates. To overcome this issue, we set out to develop DNAzymes that cleave L-RNA, the enantiomer of D-RNA, which is known to be completely resistant to RNases. Through in vitro selection we isolated three L-RNA-cleaving DNAzymes from a random-sequence DNA pool. The most active DNAzyme exhibits a catalytic rate constant ~3 min-1 and has a structure that contains a kissing loop, a structural motif that has never been observed with D-RNA-cleaving DNAzymes. Furthermore we have used this DNAzyme and a well-known ATP-binding DNA aptamer to construct an aptazyme sensor and demonstrated that this biosensor can achieve ATP detection in biological samples that contain RNases. The current work lays the foundation for exploring RNA-cleaving DNAzymes for engineering biosensors that are compatible with complex biological samples.

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