RNA sequencing of circRNAs in liver

Nonalcoholic fatty liver disease (NAFLD) is characterized by the accumulation of lipids in hepatocytes and closely associated with insulin resistance, abnormal metabolism, and oxidative stress. NAFLD encompasses a broad spectrum of conditions, from simple steatosis, through non-alcoholic steatohepatitis, to fibrosis and ultimately cirrhosis and hepatocellular carcinoma. It has become the most common cause of chronic liver diseases, affecting the worldwide population. The public health and economic burdens of NAFLD have provoked intense interest in its pathogenesis and impacts. Over the past decades, it has been demonstrated that NAFLD is associated with an increased risk of cardiovascular diseases, diabetes, and bone metabolic diseases. A growing body of studies indicate that NAFLD alters the secretion of endocrine factors from liver, such as cytokines, hepatokines, and inflammatory mediators, to influence metabolic processes in extrahepatic organs and tissues.circular RNAs (circRNAs) are a novel type of noncoding RNAs generated by precursor mRNAs through back-splicing and are characterized by covalently closed continuous loops without a terminal cap and polyadenylate tail. They have the advantages of stability, conservation, and tissue specificity. circRNAs are involved in various cellular processes, such as cell proliferation and differentiation, via diverse mechanisms. Emerging studies have demonstrated that circRNAs are abundantly expressed in liver and the alteration of expression pattern is correlated with the severity of NAFLD. However, the effect of circRNAs alteration induced by NAFLD on metabolic processes of extrahepatic organs and tissues is unclear.