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Idiopathic pulmonary fibrosis (IPF) is a fatal and incurable chronic interstitial lung disease with an unknown etiology. Recent evidence suggests that epithelial-mesenchymal transition (EMT) is one of the possible factors in the pathogenesis of pulmonary fibrosis. Glycyrrhizic acid (GA) is a natural active ingredient extracted from the root of the traditional Chinese herb licorice, which has been shown in previous studies to have the effect of alleviating lung injury. In this study, our objective was to investigate whether GA could ameliorate pulmonary fibrosis by altering EMT, as well as the therapeutic potential of changing core fucosylation (CF) to target EMT-related pathways. First, we verified that GA partially reverses EMT in a rat model of bleomycin-induced lung interstitial fibrosis, alleviating pulmonary fibrosis, and implying that GA has antifibrotic potential. Next, we discovered that GA attenuated lung interstitial fibrosis by reducing CF modifications to some extent. Interestingly, we found that GA therapy reduced the expression of phosphorylated Smad2/3 (p-Smad2/3) and β-catenin in the EMT pathway and that GA inhibited the modification of TGF-βR and WNT receptor proteins by CF, suggesting that GA may interfere with the EMT process by modulating TGF-βR, WNT core fucosylation modifications to attenuate pulmonary fibrosis. In conclusion, these findings indicate that GA could be a potential therapeutic agent for IPF, and further support the idea that targeting CF alterations could be a novel technique for the treatment of diseases involving EMT. [ABSTRACT FROM AUTHOR]

The profibrotic cytokine transforming growth factor-β1 (TGF-β1) causes renal fibrosis by binding to receptors at the cell surface; however, it is not clear which of the TGF-β superfamily receptors correlates with renal fibrosis. To resolve this, we quantified TGF-β superfamily receptor expression in the kidneys of rats with unilateral ureteral obstruction using a real-time PCR gene array. Expression of activin receptor-like kinase (ALK)-5, ALK7, and TGF-β receptor II (TGF-βRII) mRNA increased significantly, while ALK6 mRNA expression was significantly decreased in the obstructed rat kidney. Core fucosylation is essential for the proper function of both TGF-βRII and ALK5 in cultured human renal proximal tubular epithelial cells in vitro. Therefore, we targeted posttranslational core fucosylation, regulated by α-1,6 fucosyltransferase (FUT8), by adenoviral-mediated knockdown of FUT8 mRNA in vivo and measured TGF-βRII and ALK5 expression and the progression of renal fibrosis. Despite long-term obstruction injury, inhibition of TGF-βRII and ALK5 of core fucosylation ameliorated the progression of renal fibrosis, an effect independent of TGF-βRII and ALK5 expression. Thus, the regulation of TGF-β1-receptor core fucosylation may provide a novel potential therapeutic strategy for treating renal fibrosis. [ABSTRACT FROM AUTHOR]

Pulmonary fibrosis is a common outcome of a variety of pulmonary interstitial diseases, and myofibroblasts are the main culprit for this process. Recent studies have found that pericytes are one of the major sources of myofibroblasts; the transformation of which involves a complex process of activation of TGF-β/Smad2/3 and PDGFβ/Erk signaling pathways. We have reported that the transforming growth factor-β receptor and platelet-derived growth factor-β receptor (TGF-βR I and PDGFβR, respectively) are modified by glycosylation. Thus, we hope to regulate the above-mentioned signal pathways through core fucosylation (CF) catalyzed by α-1,6-fucosyltransferase (FUT8). Previous work has confirmed that TGF-β1 can induce the transformation of pericytes into myofibroblasts, while FUT8siRNA can inhibit such transformation. In the present study, we used an adenovirus packaging FUT8 shRNA to infect a bleomycin-induced pulmonary fibrosis mouse model and determined the effect of CF on pulmonary fibrosis by analyzing the mechanism of CF-mediated pericyte transformation. Our findings may shed new light on the mechanism of pulmonary interstitial fibrosis and provide a novel therapeutic target for clinical applications. [ABSTRACT FROM AUTHOR]