Activation of hepatic stellate cells (HSCs) is a pivotal event in liver fibrosis, characterized by enhanced retinoic acid signals. Although up-regulated retinoic acid signal responds further to maintain HSC activation, the underlying molecular mechanisms are largely unknown. In this study, we sought to investigate the role of lncRNA-H19 in regulation of retinoic acid signals, and to further examine the underlying mechanism in this molecular context. We found that lncRNA-H19 upregulation could enhance retinoic acid signals to induce HSC activation, whereas lncRNA-H19 knockdown completely disturbed retinoic acid signals. Moreover, the activation of retinoic acid signals impaired the lncRNA-H19 knockdown mediated HSC inactivation. Interestingly, we also found that enhanced retinoic acid signals by lncRNA-H19 was associated with a coordinate increase in retinol metabolism during HSC activation. Increased retinol metabolism contributed to obvious lipid droplet consumption. Importantly, we identified that alcohol dehydrogenase III (ADH3) was essential for lncRNA-H19 to enhance retinoic acid signals. The inhibition of ADH3 completely abrogated the lncRNA-H19 mediated retinoic acid signals and HSC activation. Of note, we identified dihydroartemisinin (DHA) as a natural inhibitor for lncRNA-H19. Treatment with DHA significantly decreased the expression of lncRNA-H19, reduced the expression of ADH3, blocked retinoic acid signals, and in turn, inhibited HSC activation. Overall, these results provided novel implications to reveal the molecular mechanism of increased retinoic acid signals during HSC activation, and identify lncRNA-H19/ADH3 pathway as a potential target for the treatment of liver fibrosis.
Keywords: Alcohol dehydrogenase III; Dihydroartemisinin; Lipid droplet; LncRNA-H19; Retinoic acid signals.
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