Apolipoprotein A-1 Accelerated Liver Regeneration Through Regulating Autophagy Via AMPK-ULK1 Pathway.

BACKGROUND & AIMS: Apolipoprotein A-1 (ApoA-1), the main apolipoprotein of high-density lipoprotein, has been well studied in the area of lipid metabolism and cardiovascular diseases. In this project, we clarify the function and mechanism of ApoA-1 in liver regeneration. METHODS: Seventy percent of partial hepatectomy was applied in male ApoA-1 knockout mice and wild-type mice to investigate the effects of ApoA-1 on liver regeneration. D-4F (ApoA-1 mimetic peptide), autophagy activator, and AMPK activator were used to explore the mechanism of ApoA-1 on liver regeneration. RESULTS: We demonstrated that ApoA-1 levels were highly expressed during the early stage of liver regeneration. ApoA-1 deficiency greatly impaired liver regeneration after hepatectomy. Meanwhile, we found that ApoA-1 deficiency inhibited autophagy during liver regeneration. The activation of autophagy protected against ApoA-1 deficiency in inhibiting liver regeneration. Furthermore, ApoA-1 deficiency impaired autophagy through AMPK-ULK1 pathway, and AMPK activation significantly improved liver regeneration. The administration of D-4F could accelerated liver regeneration after hepatectomy. CONCLUSIONS: These findings suggested that ApoA-1 played an essential role in liver regeneration through promoting autophagy in hepatocytes via AMPK-ULK1 pathway. Our findings enrich the understanding of the underlying mechanism of liver regeneration and provide a potential therapeutic strategy for liver injury.

CircUGP2 Suppresses Intrahepatic Cholangiocarcinoma Progression via p53 Signaling Through Interacting With PURB to Regulate ADGRB1 Transcription and Sponging miR-3191-5p.

Intrahepatic cholangiocarcinoma (ICC) is the second most common primary liver cancer and its prognosis remains poor. Although growing numbers of studies have verified the involvement of circular RNAs (circRNAs) in various cancer types, their specific functions in ICC remain elusive. Herein, a circRNA, circUGP2 is identified by circRNA sequencing, which is downregulated in ICC tissues and correlated with patients' prognosis. Moreover, circUGP2 overexpression suppresses tumor progression in vitro and in vivo. Mechanistically, circUGP2 functions as a transcriptional co-activator of PURB over the expression of ADGRB1. It can also upregulate ADGRB1 expression by sponging miR-3191-5p. As a result, ADGRB1 prevents MDM2-mediated p53 polyubiquitination and thereby activates p53 signaling to inhibit ICC progression. Based on these findings, circUGP2 plasmid is encapsulated into a lipid nanoparticle (LNP) system, which has successfully targeted tumor site and shows superior anti-tumor effects. In summary, the present study has identified the role of circUGP2 as a tumor suppressor in ICC through regulating ADGRB1/p53 axis, and the application of LNP provides a promising translational strategy for ICC treatment.