Imbalance in lipid metabolism induces steatosis in liver during Chronic hepatitis C (CHC). Contribution of microRNAs in regulating lipid homoeostasis and liver disease progression is well established using small RNA-transcriptome data. Owing to the complexity in the development of liver diseases, the existence and functional importance of yet undiscovered regulatory miRNAs in disease pathogenesis was explored in this study using the unmapped sequences of the transcriptome data of HCV-HCC liver tissues following miRDeep2.pl pipeline. MicroRNA-c12 derived from the first intron of LGR5 of chromosome 12 was identified as one of the miRNA like sequences retrieved in this analysis that showed human specific origin. Northern blot hybridization has proved its existence in the hepatic cell line. Enrichment of premiR-c12 in dicer-deficient cells and miR-c12 in Ago2-RISC complex clearly suggested that it followed canonical miRNA biogenesis pathway and accomplished its regulatory function. Expression of this miRNA was quite low in CHC tissues than normal liver implying HCV-proteins might be regulating its biogenesis. Promoter scanning and ChIP analysis further revealed that under expression of p53 and hyper-methylation of STAT3 binding site upon HCV infection restricted its expression in CHC tissues. Centrosomal protein 350 (CEP350), which sequestered PPARα, was identified as one of the targets of miR-c12 using Miranda and validated by luciferase assay/western blot analysis. Furthermore, reduced triglyceride accumulation and enhanced PPARα mediated transcription of β-oxidation genes upon restoration of miR-c12 in liver cells suggested its role in lipid catabolism. Thus this study is reporting miR-c12 for the first time and showed its’ protective role during chronic HCV infection.

在慢性丙型肝炎 (CHC) 期间，脂质代谢的不平衡会导致肝脏脂肪变性。使用小 RNA 转录组数据已经很好地确定了 microRNA 在调节脂质稳态和肝脏疾病进展中的作用。由于肝病发展的复杂性，本研究使用 miRDeep2.pl 管道后的 HCV-HCC 肝组织转录组数据的未映射序列探索了尚未发现的调节性 miRNA 在疾病发病机制中的存在和功能重要性。来自 12 号染色体 LGR5 第一个内含子的 MicroRNA-c12 被鉴定为该分析中检索到的一种 miRNA 样序列，显示出人类特定的起源。Northern印迹杂交已证明其存在于肝细胞系中。切丁酶缺陷细胞中 premiR-c12 和 Ago2-RISC 复合物中 miR-c12 的富集清楚地表明它遵循典型的 miRNA 生物发生途径并完成其调节功能。这种 miRNA 在 CHC 组织中的表达比正常肝脏低，这意味着 HCV 蛋白可能正在调节其生物发生。启动子扫描和 ChIP 分析进一步显示，HCV 感染后 p53 的低表达和 STAT3 结合位点的高甲基化限制了其在 CHC 组织中的表达。隔离 PPARα 的中心体蛋白 350 (CEP350) 被 Miranda 鉴定为 miR-c12 的靶标之一，并通过荧光素酶测定/蛋白质印迹分析进行验证。此外，肝细胞中 miR-c12 恢复后甘油三酯积累减少和 PPARα 介导的 β-氧化基因转录增强表明其在脂质分解代谢中的作用。因此，本研究首次报告了 miR-c12，并显示了其在慢性 HCV 感染期间的保护作用。