The impact and role of identified long noncoding RNAs in nonalcoholic fatty liver disease: A narrative review

Role of long non-coding RNAs in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is emerging as a common cause of chronic liver disease in children and adults. NAFLD can progress to steatohepatitis and potentially even hepatocellular carcinoma. Early identification of patients at risk for progressive disease is crucial for managing NAFLD. Recent studies have identified long noncoding RNAs (lncRNAs), circular RNAs, and microRNAs as playing important roles in the pathogenesis of NAFLD. These noncoding RNAs are involved in modulating several metabolic pathways such as hepatic glucose and lipid metabolism, oxidative stress, and even carcinogenesis. Elevated levels of lncARSR and lncRNA nuclear-enriched abundant transcript 1 have been found in patients with NAFLD. In addition, lncRNAs such as PRYP4-3 and RP11-128N14.5 can distinguish patients with NAFLD from healthy individuals. Increased MEG3 expression has been observed in both NAFLD and non-alcoholic steatohepatitis, suggesting that it may help predict patients at risk for disease progression. With advances in transcriptomics, we may discover additional targets to help in the identification and prognostication of NAFLD.

Long Noncoding RNAs in Diet-Induced Metabolic Diseases

The prevalence of metabolic diseases, including type 2 diabetes and metabolic dysfunction-associated steatotic liver disease (MASLD), is steadily increasing. Although many risk factors, such as obesity, insulin resistance, or hyperlipidemia, as well as several metabolic gene programs that contribute to the development of metabolic diseases are known, the underlying molecular mechanisms of these processes are still not fully understood. In recent years, it has become evident that not only protein-coding genes, but also noncoding genes, including a class of noncoding transcripts referred to as long noncoding RNAs (lncRNAs), play key roles in diet-induced metabolic disorders. Here, we provide an overview of selected lncRNA genes whose direct involvement in the development of diet-induced metabolic dysfunctions has been experimentally demonstrated in suitable in vivo mouse models. We further summarize and discuss the associated molecular modes of action for each lncRNA in the respective metabolic disease context. This overview provides examples of lncRNAs with well-established functions in diet-induced metabolic diseases, highlighting the need for appropriate in vivo models and rigorous molecular analyses to assign clear biological functions to lncRNAs.

Investigating the Role of Non-Coding RNA in Non-Alcoholic Fatty Liver Disease

Non-coding RNAs (ncRNAs) are RNA molecules that do not code for protein but play key roles in regulating cellular processes. NcRNAs globally affect gene expression in diverse physiological and pathological contexts. Functionally important ncRNAs act in chromatin modifications, in mRNA stabilization and translation, and in regulation of various signaling pathways. Non-alcoholic fatty liver disease (NAFLD) is a set of conditions caused by the accumulation of triacylglycerol in the liver. Studies of ncRNA in NAFLD are limited but have demonstrated that ncRNAs play a critical role in the pathogenesis of NAFLD. In this review, we summarize NAFLD's pathogenesis and clinical features, discuss current treatment options, and review the involvement of ncRNAs as regulatory molecules in NAFLD and its progression to non-alcoholic steatohepatitis (NASH). In addition, we highlight signaling pathways dysregulated in NAFLD and review their crosstalk with ncRNAs. Having a thorough understanding of the disease process's molecular mechanisms will facilitate development of highly effective diagnostic and therapeutic treatments. Such insights can also inform preventive strategies to minimize the disease's future development.