RPA1 Remodels Liver Chromatin Architecture to Maintain Lipid Metabolic Homeostasis

Replication protein A(RPA), a ssDNA binding protein complex, participates in DNA replication, recombination and damage repair, but its physiological function remains elusive. Here, we show that heterozygous Rpa1 knockout mice were developmentally normal, but hypersensitive to ageing and high-fat-diet (HFD) induced hepatic steatosis. Liver specific deletion of Rpa1 leads to impaired lipid beta-oxidation, hepatic steatosis and subsequently hepatocellular carcinoma (HCC). Assays for RNA-seq, pull-down and transposase-accessible chromatin sequencing (ATAC-seq) reveal that RPA1 is required for transcription of a subgroup of lipid metabolic genes via altering chromatin accessibility landscape. Thus, our results suggest that RPA1 is a critical regulator of gene transcription and chromatin remodeling, linking a guardian of genome stability to lipid metabolic homeostasis. Liver mRNA profiles of 3 liver specific Rpa1 knockout mice and 3 wild type (WT) mice were generated for RNA-seq. And chromatin accessibility in liver tissue of 4 liver specific Rpa1 knockout mice and 4 wild type (WT) mice were examined by ATAC-seq.复制蛋白A（Replication protein A, RPA）是一类单链DNA（single-stranded DNA, ssDNA）结合蛋白复合物，参与DNA复制、重组与损伤修复，但其生理功能仍未完全明晰。本研究发现，杂合子Rpa1敲除小鼠发育表型正常，但对衰老及高脂饮食（high-fat diet, HFD）诱导的肝脂肪变性具有高度易感性。肝脏特异性敲除Rpa1会导致脂质β氧化受损、肝脂肪变性，进而引发肝细胞癌（hepatocellular carcinoma, HCC）。通过RNA测序（RNA-seq）、下拉实验（pull-down）及转座酶可及性染色质测序（transposase-accessible chromatin sequencing, ATAC-seq）等实验分析，本研究揭示RPA1可通过重塑染色质可及性图谱，调控一类脂质代谢基因的转录。综上，本研究结果表明RPA1是基因转录与染色质重塑的关键调控因子，将基因组稳定性守护者与脂质代谢稳态建立了关联。本研究对3只肝脏特异性Rpa1敲除小鼠及3只野生型（wild type, WT）小鼠的肝脏mRNA表达谱开展了RNA-seq测序；同时通过ATAC-seq检测了4只肝脏特异性Rpa1敲除小鼠与4只野生型小鼠肝脏组织的染色质可及性水平。