Liver fibrosis is characterized by the activation and transformation of hepatic stellate cells (HSCs) induced by various injury factors. The degree of liver fibrosis can be significantly improved, but persistent injury factors present a significant therapeutic challenge. Hepatocytes are the most important parenchymal cell type in the liver. In this study, we explored the molecular mechanisms by which damaged liver cells activate HSCs through extracellular vesicles. We established a coculture model of LO2 and LX2 and validated its exosomal transmission activity. Subsequently, differentially expressed long noncoding RNAs (lncRNAs) were screened through RNA sequencing and their mechanisms of action as competing endogenous RNAs (ceRNAs) further confirmed using biological methods, such as FISH and luciferase assays. Damaged liver cells induced activation of LX2 and upregulation of liver fibrosis‐related markers. Exosomes extracted and identified from the supernatant fraction contained differentially expressed lncRNA cytoskeleton regulator RNA (CYTOR) that competed with microRNA‐125 (miR‐125) for binding to glial cell line‐derived neurotrophic factor (GDNF) in HSCs, in turn, promoting LX2 activation. MiR‐125 could target and regulate both CYTOR and GDNF and vice versa, as verified using the luciferase assay. In an in vivo model, damaged liver extracellular vesicles induced the formation of liver fibrosis. Notably, downregulation of CYTOR within extracellular vesicles effectively inhibited liver fibrosis. The lncRNA CYTOR in exosomes of damaged liver cells is upregulated and modulates the expression of downstream GDNF through activity as a ceRNA, providing an effective mechanism for activation of HSCs.

中文翻译：

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肝细胞源性外泌体将lncRNA CYTOR传递至肝星状细胞并促进肝纤维化

肝纤维化的特征是各种损伤因素诱导的肝星状细胞（HSC）的激活和转化。肝纤维化程度可以显着改善，但持续的损伤因素提出了重大的治疗挑战。肝细胞是肝脏中最重要的实质细胞类型。在这项研究中，我们探讨了受损肝细胞通过细胞外囊泡激活 HSC 的分子机制。我们建立了LO2和LX2的共培养模型并验证了其外泌体传输活性。随后，通过RNA测序筛选差异表达的长非编码RNA（lncRNA），并使用FISH和荧光素酶测定等生物学方法进一步证实其作为竞争性内源RNA（ceRNA）的作用机制。受损的肝细胞诱导 LX2 激活和肝纤维化相关标志物上调。从上清液中提取和鉴定的外泌体含有差异表达的 lncRNA 细胞骨架调节 RNA (CYTOR)，它与 ​​microRNA-125 (miR-125) 竞争结合 HSC 中的胶质细胞系源性神经营养因子 (GDNF)，进而促进 LX2激活。使用荧光素酶测定验证，MiR-125 可以靶向并调节 CYTOR 和 GDNF，反之亦然。在体内模型中，受损的肝细胞外囊泡诱导肝纤维化的形成。值得注意的是，细胞外囊泡内 CYTOR 的下调可有效抑制肝纤维化。受损肝细胞外泌体中的 lncRNA CYTOR 上调，并通过 ceRNA 活性调节下游 GDNF 的表达，为 HSC 的激活提供有效机制。