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Long Non-coding RNA Growth Arrest-specific Transcript 5 (GAS5) Inhibits Liver Fibrogenesis through a Mechanism of
Fujun Yu1, Jianjian Zheng2, Yuqing Mao1
1Department of Gastroenterology, Jinshan Hospital of Fudan University, Jinshan, Shanghai 201508, China.
Abstract:
Effective control of hepatic stellate cell (HSC) activation and proliferation is critical to the treatment of liver fibrosis. Long non-coding RNAs have been shown to play a pivotal role in the regulation of cellular processes. It has been reported that growth arrest-specific transcript 5 (GAS5) acts as a crucial mediator in the control of cell proliferation and growth. However, little is known about the role and underlying mechanism of GAS5 in liver fibrosis. In this study, our results indicated that GAS5 expression was reduced in mouse, rat, and human fibrotic liver samples and in activated HSCs. Overexpression of GAS5 suppressed the activation of primary HSCs in vitro and alleviated the accumulation of collagen in fibrotic liver tissues in vivo. We identified GAS5 as a target of microRNA-222 (miR-222) and showed that miR-222 could inhibit the expression of GAS5. Interestingly, GAS5 could also repress miR-222 expression. A pulldown assay further validated that GAS5 could directly bind to miR-222. As a competing endogenous RNAs, GAS5 had no effect on primary miR-222 expression. In addition, GAS5 was mainly localized in the cytoplasm. Quantitative RT-PCR further demonstrated that the copy numbers of GAS5 per cell are higher than those of miR-222. GAS5 increased the level of p27 protein by functioning as a competing endogenous RNA for miR-222, thereby inhibiting the activation and proliferation of HSCs. Taken together, a new regulatory circuitry in liver fibrosis has been identified in which RNAs cross-talk by competing for shared microRNAs. Our findings may provide a new therapeutic strategy for liver fibrosis.
Insights
Growth arrest-specific transcript 5 (GAS5) is reduced in liver fibrosis. Upregulating GAS5 inhibits hepatic stellate cell activation and proliferation, offering a potential new therapy for liver fibrosis.
Area of Science:
- Molecular biology
- Cell biology
- Gastroenterology
Background:
- Liver fibrosis is a significant health issue requiring effective therapeutic strategies.
- Long non-coding RNAs (lncRNAs) regulate cellular processes, including cell proliferation and growth.
- Growth arrest-specific transcript 5 (GAS5) is implicated in cell proliferation control, but its role in liver fibrosis is unclear.
Purpose of the Study:
- To investigate the role and mechanism of GAS5 in liver fibrosis.
- To explore the regulatory relationship between GAS5 and microRNA-222 (miR-222) in hepatic stellate cells (HSCs).
Main Methods:
- Quantitative RT-PCR to measure GAS5 and miR-222 expression in fibrotic liver samples and HSCs.
- In vitro experiments overexpressing GAS5 in primary HSCs.
- In vivo studies assessing collagen accumulation in fibrotic liver tissues.
- Pulldown assays to confirm direct binding between GAS5 and miR-222.
- Western blotting to analyze p27 protein levels.
Main Results:
- GAS5 expression was significantly reduced in fibrotic liver tissues and activated HSCs from mouse, rat, and human samples.
- Overexpression of GAS5 suppressed HSC activation in vitro and reduced collagen accumulation in vivo.
- GAS5 and miR-222 directly interact and regulate each other's expression, with GAS5 acting as a competing endogenous RNA for miR-222.
- GAS5 upregulates p27 protein levels, inhibiting HSC activation and proliferation.
Conclusions:
- GAS5 plays a protective role in liver fibrosis by inhibiting HSC activation and proliferation.
- A novel regulatory feedback loop between GAS5 and miR-222 is identified in liver fibrosis.
- GAS5's mechanism involves acting as a competing endogenous RNA to increase p27 levels.
- Targeting the GAS5-miR-222 axis presents a potential therapeutic strategy for liver fibrosis.
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