Dynamic remodeling of translation programs drives hepatocyte proliferation during liver regeneration

During liver regeneration, most new hepatocytes arise from pre-existing ones; yet, the underlying mechanisms that drive these cells from quiescence to proliferation remain poorly defined. By using high-resolution transcriptome profiling of polysome fractions from purified hepatocytes isolated from quiescent and toxin-injured adult mouse livers,we uncover the mRNA transcripts regulated during liver regeneration. The translational remodeling modulates protein levels of a set of splicing factors including Epithelial splicing regulatory protein 2 (ESRP2), which activates an early postnatal splicing program in regenerating hepatocytes as well as metabolic genes. Hepatocytes were isolated in presence of Cycloheximide (CHX) from normal fed mice and DDC fed (4 week) mice. Polysomal fractions were separated over sucrose gradient and RNA was isolated from the three fractions Monosome (1 ribosome), Light polysome (2-4 ribosomes) and Heavy polysomes (>5). Isolated RNA was subject to polyA selection and sequenced on an Illumina platform.肝脏再生过程中，绝大多数新生肝细胞均源自已存在的肝细胞；然而，驱动此类细胞从静息状态向增殖状态转变的潜在分子机制仍未得到充分阐明。 本研究针对取自静息状态及毒素损伤成年小鼠肝脏的纯化肝细胞的多聚核糖体组分，开展高分辨率转录组谱分析，由此揭示了肝脏再生过程中受到调控的mRNA转录本。 翻译重塑过程调控了一系列剪接因子的蛋白表达水平，其中包括上皮剪接调控蛋白2（Epithelial splicing regulatory protein 2, ESRP2）；该因子可在再生肝细胞中激活早期出生后剪接程序，同时也对代谢相关基因存在调控作用。 研究人员从正常喂食小鼠及喂食DDC 4周的小鼠肝脏中分离肝细胞，分离过程中加入了环己酰亚胺（Cycloheximide, CHX）。 通过蔗糖密度梯度离心分离多聚核糖体组分，并从单核糖体（1个核糖体）、轻多聚核糖体（2-4个核糖体）及重多聚核糖体（>5个核糖体）三个组分中提取RNA。 提取得到的RNA经polyA富集筛选后，在Illumina测序平台上完成高通量测序。