Downregulation of hepatic lncRNA Gm19619 improves gluconeogenesis and lipogenesis following vertical sleeve gastrectomy in mice [ChIRP-Seq]

Long non-coding RNAs (lncRNAs) are emerging important epigenetic regulators in metabolic processes. Whether they contribute to the metabolic effects of vertical sleeve gastrectomy (VSG), one of the most effective treatments for sustainable weight loss and metabolic improvement, is unknown. Herein, we identified a hepatic lncRNA Gm19619, which was strongly repressed by VSG but highly up-regulated by diet-induced obesity and overnight-fasting in mice. Forced transcription of Gm19619 in the mouse liver significantly promoted hepatic gluconeogenesis with the elevated expression of G6pc and Pck1. In contrast, AAV-CasRx mediated knockdown of Gm19619 in HFD-fed mice significantly improved hepatic glucose and lipid metabolism. Mechanistically, Gm19619 was enriched along genomic regions encoding leptin receptor (Lepr) and the transcriptional factor Foxo1, as revealed in chromatin isolation by RNA purification (ChIRP) assay and was confirmed to modulate their transcription in the mouse liver. In conclusion, Gm19619 may enhance gluconeogenesis and lipid metabolism in the liver. Chromatin isolation by RNA purification from mouse primary hepatocytes, followed by DNA-seq.

长链非编码RNA（long non-coding RNAs, lncRNAs）是一类在代谢过程中愈发受到关注的重要表观遗传调控因子。袖状胃切除术（vertical sleeve gastrectomy, VSG）作为实现可持续减重与代谢改善的最有效治疗手段之一，其代谢效应是否由lncRNAs介导仍未明确。
本研究中，我们在小鼠肝脏内鉴定出一种lncRNA Gm19619：该分子的表达可被VSG显著抑制，却在饮食诱导肥胖小鼠与过夜禁食小鼠中显著上调。
在小鼠肝脏中强制过表达Gm19619，可显著促进肝脏糖异生，并伴随G6pc与Pck1的表达水平升高。
与之相反，在高脂饮食喂养的小鼠中利用腺相关病毒-CasRx（AAV-CasRx）介导敲低Gm19619，可显著改善肝脏糖脂代谢。
机制研究显示，通过RNA纯化染色质分离（chromatin isolation by RNA purification, ChIRP）实验发现，Gm19619可富集于瘦素受体（leptin receptor, Lepr）与转录因子Foxo1的编码基因组区域，并在小鼠肝脏中证实其可调控这两个基因的转录。
综上，Gm19619可增强肝脏糖异生与脂质代谢。本研究采用从小鼠原代肝细胞中开展RNA纯化染色质分离实验，随后进行DNA测序（DNA-seq）。