BACKGROUND Yes-associated protein 1(YAP1),a downstream transcriptional coactivator regulated by the Hippo signaling pathway,has been shown to be involved in liver fibrosis.YAP activity is modulated by G-protein couple...BACKGROUND Yes-associated protein 1(YAP1),a downstream transcriptional coactivator regulated by the Hippo signaling pathway,has been shown to be involved in liver fibrosis.YAP activity is modulated by G-protein coupled receptors,including Gαs-coupled protein dopamine receptor D1(DRD1).Levodopa,a dopamine precursor,activates DRD1 on cell surface,triggering its downstream signaling pathway.AIM To investigate the therapeutic effect of levodopa and the downstream mechanism on carbon tetrachloride(CCl_(4))-induced liver fibrosis,including liver DRD1 expression.METHODS SD rats were intraperitoneally injected with 40%CCl_(4)for 8 weeks to induce liver fibrosis,followed by treatment with varying doses of levodopa for 2 weeks.Serum aspartate aminotransferase(AST)and alanine aminotransferase(ALT)levels were measured,and liver pathology was assessed using hematoxylin and eosin and Masson's staining.Alpha-smooth muscle actin(α-SMA)content,along with the expressions of DRD1,YAP,and phosphorylated protein,was analyzed by Western blot,immunohistochemistry,and reverse transcription-quantitative real-time polymerase chain reaction.RESULTS Compared with the controls,levodopa-treated rats showed a decrease in the proportion of collagen in the liver and a recovery from liver fibrosis(P=0.0007).Western blot and immunohistochemistry indicated that DRD1 was upregulated in the fibrotic liver of rats treated with levodopa,showing an increase in DRD1 Level(P<0.0001).In addition,the upregulation of DRD1 activated the Hippo signaling pathway,manifested as increased YAP phosphorylation(P<0.05).CONCLUSION This was the first study to demonstrate that levodopa attenuates CCl_(4)-induced liver fibrosis by inhibiting the Hippo/YAP signaling pathways.展开更多
文摘BACKGROUND Yes-associated protein 1(YAP1),a downstream transcriptional coactivator regulated by the Hippo signaling pathway,has been shown to be involved in liver fibrosis.YAP activity is modulated by G-protein coupled receptors,including Gαs-coupled protein dopamine receptor D1(DRD1).Levodopa,a dopamine precursor,activates DRD1 on cell surface,triggering its downstream signaling pathway.AIM To investigate the therapeutic effect of levodopa and the downstream mechanism on carbon tetrachloride(CCl_(4))-induced liver fibrosis,including liver DRD1 expression.METHODS SD rats were intraperitoneally injected with 40%CCl_(4)for 8 weeks to induce liver fibrosis,followed by treatment with varying doses of levodopa for 2 weeks.Serum aspartate aminotransferase(AST)and alanine aminotransferase(ALT)levels were measured,and liver pathology was assessed using hematoxylin and eosin and Masson's staining.Alpha-smooth muscle actin(α-SMA)content,along with the expressions of DRD1,YAP,and phosphorylated protein,was analyzed by Western blot,immunohistochemistry,and reverse transcription-quantitative real-time polymerase chain reaction.RESULTS Compared with the controls,levodopa-treated rats showed a decrease in the proportion of collagen in the liver and a recovery from liver fibrosis(P=0.0007).Western blot and immunohistochemistry indicated that DRD1 was upregulated in the fibrotic liver of rats treated with levodopa,showing an increase in DRD1 Level(P<0.0001).In addition,the upregulation of DRD1 activated the Hippo signaling pathway,manifested as increased YAP phosphorylation(P<0.05).CONCLUSION This was the first study to demonstrate that levodopa attenuates CCl_(4)-induced liver fibrosis by inhibiting the Hippo/YAP signaling pathways.
