Chromatin binding protein HMGN1 promotes HBV cccDNA transcription and replication by regulating the phosphorylation of histone 3.

BACKGROUND AND AIMS: Direct elimination of cccDNA remains a formidable obstacle due to the persistent and stable presence of cccDNA in hepatocyte nuclei. The silencing of cccDNA transcription enduringly is one of alternative strategies in the treatment of hepatitis B. Protein binding to cccDNA plays an important role in its transcriptional regulation; thus, the identification of key factors involved in this process is of great importance. APPROACHES AND RESULTS: In the present study, high mobility group nucleosome binding domain 1 (HMGN1) was screened out based on our biotin-avidin enrichment system. First, chromatin immunoprecipitation and fluorescent in situ hybridization assays confirmed the binding of HMGN1 with cccDNA in the nucleus. Second, functional experiments in HBV-infected cells showed that the promoting effect of HMGN1 on HBV transcription and replication depended on the functional region of the nucleosomal binding domain, while transfection of the HMGN1 mutant showed no influence on HBV compared with the vector. Third, further mechanistic exploration revealed that the silencing of HMGN1 increased the level of phosphorylase CLK2 and promoted H3 phosphorylation causing the reduced accessibility of cccDNA. Moreover, silenced HMGN1 was mimicked in HBV (r) cccDNA mouse model of HBV infection in vivo. The results showed that silencing HMGN1 inhibited HBV replication in vivo. CONCLUSIONS: In summary, our study identified that a host protein can bind to cccDNA and promote its transcription, providing a candidate strategy for anti-HBV targeting to interfere with the transcriptional activity of cccDNA microchromosomes.

Mechanism of amino acid metabolism in nonalcoholic fatty liver disease / 临床肝胆病杂志

Nonalcoholic fatty liver disease （NAFLD） is one of the most prevalent chronic liver diseases in the world， affecting about one quarter of the global population， and it is estimated that NAFLD will become the main indication for liver transplantation by 2030. NAFLD can lead to significant abnormalities in the levels of a variety of amino acids including branched-chain amino acids， thereby promoting the development and progression of NAFLD. These results suggest that in addition to glucose and lipid metabolism， amino acid metabolism also plays an important role in the progression of NAFLD. In order to systematically understand the role and mechanism of amino acid metabolism in NAFLD， this article reviews the research advances in amino acid metabolism in NAFLD. This article aims to explore the role and mechanism of amino acid metabolism in the progression of NAFLD， so as to provide ideas and a theoretical basis for clinical prevention and treatment.