Long Noncoding RNAs in the Pathogenesis of Insulin Resistance

Emerging regulatory roles of noncoding RNAs induced by bisphenol a (BPA) and its alternatives in human diseases

Bisphenols (BPs), including BPA, BPF, BPS, and BPAF, are synthetic phenolic organic compounds and endocrine-disrupting chemicals. These organics have been broadly utilized to produce epoxy resins, polycarbonate plastics, and other products. Mounting evidence has shown that BPs, especially BPA, may enter into the human body and participate in the development of human diseases mediated by nuclear hormone receptors. Moreover, BPA may negatively affect human health at the epigenetic level through processes such as DNA methylation and histone acetylation. Recent studies have demonstrated that, as part of epigenetics, noncoding RNAs (ncRNAs), including microRNAs (miRNAs), long noncoding RNAs (lncRNAs), circular RNAs (circRNAs), and small nucleolar RNAs (snoRNAs), have vital impacts on BP-related diseases, such as reproductive system diseases, nervous system diseases, digestive system diseases, endocrine system diseases, and other diseases. Moreover, based on the bioinformatic analysis, changes in ncRNAs may be relevant to normal activities and functions and BP-induced diseases. Thus, we conducted a meta-analysis to identify more promising ncRNAs as biomarkers and therapeutic targets for BP exposure and relevant human diseases. In this review, we summarize the regulatory functions of ncRNAs induced by BPs in human diseases and latent molecular mechanisms, as well as identify prospective biomarkers and therapeutic targets for BP exposure and upper diseases.

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.

Molecular Insights of Nonalcoholic Fatty Liver Disease Pathogenesis

Nonalcoholic fatty liver disease (NAFLD) is now the most prevalent chronic liver disease. Many hepatic abnormalities are associated with NAFLD such as nonalcoholic steatohepatitis, progressive fibrosis, cirrhosis, and liver failure. Moreover, the pathogenesis of NAFLD has numerous etiologies and can be explained due to the existence of several of stimulus that act simultaneously on genetically susceptible patients. These stimuli include obesity, diabetes, and insulin resistance. In addition, identifying the role of gut microbiota on NAFLD progression has been illustrated. In this review, we clarified the several factors that lead to the development of NAFLD and identify those who are most at risk of developing liver end-stage disease. Highlighting the noninvasive diagnostic NAFLD markers could be helpful in the disease prevention and treatment approaches.

Altered expression of long noncoding RNA MEG3 in the offspring of gestational diabetes mellitus induces impaired glucose tolerance in adulthood

AIM

Gestational diabetes mellitus (GDM) affects a significant number of women worldwide and has been associated with lifelong health consequences for their offspring, including increased susceptibility to obesity, insulin resistance, and type II diabetes. Recent studies have suggested that aberrant expression of the long non-coding RNA Meg3 in the liver may contribute to impaired glucose metabolism in individuals. In this study, we aimed to investigate whether intrauterine exposure to hyperglycemia affects glucose intolerance in puberty by mediating the overexpression of LncMeg3 in the liver.

METHODS

To test our hypothesis, we established an animal model of intrauterine hyperglycemia to mimic GDM. The progeny was observed for phenotypic changes, and intraperitoneal glucose tolerance tests, insulin tolerance tests, and pyruvate tolerance tests were conducted to assess glucose and insulin tolerance. We also measured LncMeg3 expression in the liver using real-time quantitative PCR and examined differential methylation areas (DMRs) in the Meg3 gene using pyrophosphoric sequencing. To investigate the role of LncMeg3 in glucose tolerance, we conducted Meg3 intervention by vein tail and analyzed the changes in the phenotype and transcriptome of the progeny using bioinformatics analysis.

RESULTS

We found that intrauterine exposure to hyperglycemia led to impaired glucose and insulin tolerance in the progeny, with a tendency toward increased fasting blood glucose in fat offspring at 16 weeks (P = 0.0004). LncMeg3 expression was significantly upregulated (P = 0.0061), DNMT3B expression downregulated (P = 0.0226), and DNMT3A (P = 0.0026), TET2 (P = 0.0180) expression upregulated in the liver. Pyrophosphoric sequencing showed hypomethylation in Meg3-DMRs (P = 0.0005). Meg3 intervention by vein tail led to a decrease in the percentage of obese and emaciated offspring (emaciation: 44% vs. 23%; obesity: 25% vs. 15%) and attenuated glucose intolerance. Bioinformatics analysis revealed significant differences in the transcriptome of the progeny, particularly in circadian rhythm and PPAR signaling pathways.

CONCLUSION

In conclusion, our study suggests that hypomethylation of Meg3-DMRs increases the expression of the imprinted gene Meg3 in the liver of males, which is associated with impaired glucose tolerance in GDM-F1. MEG3 interference may attenuate glucose intolerance, which may be related to transcriptional changes. Our findings provide new insights into the mechanisms underlying the long-term effects of intrauterine hyperglycemia on progeny health and highlight the potential of Meg3 as an intervention target for glucose intolerance.

GAS5: A pivotal lncRNA in diabetes mellitus pathogenesis and management

The long non-coding RNA (lncRNA), GAS5, has garnered significant attention recently for its multifaceted involvement in cellular processes, particularly within the context of diabetes. This comprehensive review delves into the intricate molecular interactions associated with GAS5 and their profound implications for understanding, diagnosing, and effectively managing diabetes mellitus. The article begins by highlighting the global prevalence of diabetes and the urgent need for innovative insights into its underlying mechanisms and therapeutic approaches. It introduces GAS5 as a crucial regulator of gene expression, with emerging significance in the context of diabetes-related processes. The core of this review unravels the regulatory network of GAS5 in diabetes, elucidating its impact on various aspects of the disease. It explores how GAS5 influences insulin signaling pathways, glucose metabolism, and the function of β-cells, shedding light on its role in hyperglycemia and insulin resistance. Moreover, the article underscores the clinical relevance of GAS5's interactions by discussing their associations with different diabetes subtypes, predictive value, and potential applications as both diagnostic tools and therapeutic targets. It provides insights into ongoing research endeavours aimed at harnessing the potential of GAS5 for innovative disease management strategies, including the development of RNA-based therapeutics. Concluding with a forward-looking perspective, the abstract highlights the broader implications of GAS5 in the field of diabetes, such as its connection to diabetic complications and its potential for personalized approaches in disease management.

The role of lncRNAs in intermittent hypoxia and sleep Apnea: A review of experimental and clinical evidence

In this narrative review, we present a comprehensive assessment on the putative roles of long non-coding RNAs (lncRNAs) in intermittent hypoxia (IH) and sleep apnea. Collectively, the evidence from cell culture, animal, and clinical research studies points to the functional involvement of lncRNAs in the pathogenesis, diagnosis, and potential treatment strategies for this highly prevalent disorder. Further research is clearly warranted to uncover the mechanistic pathways and to exploit the therapeutic potential of lncRNAs, thereby improving the management and outcomes of patients suffering from sleep apnea.

Long non-coding RNAs and pancreatic cancer: A multifaceted view

Pancreatic cancer (PC) is a highly malignant disease with a 5-year survival rate of only 10%. Families with PC are at greater risk, as are type 2 diabetes, pancreatitis, and other factors. Insufficient early detection methods make this cancer have a poor prognosis. Additionally, the molecular mechanisms underlying PC development remain unclear. Increasing evidence suggests that long non-coding RNAs (lncRNAs) contribute to PC pathology,which may control gene expression by recruiting histone modification complexes to chromatin and interacting with proteins and RNAs. In recent studies, abnormal regulation of lncRNAs has been implicated in PC proliferation, metastasis, invasion, angiogenesis, apoptosis, and chemotherapy resistance suggesting potential clinical implications. The paper reviews the progress of lncRNA research in PC about diabetes mellitus, pancreatitis, cancer metastasis, tumor microenvironment regulation, and chemoresistance. Furthermore, lncRNAs may serve as potential therapeutic targets and biomarkers for PC diagnosis and prognosis. This will help improve PC patients' survival rate from a lncRNA perspective.

A Novel Long Noncoding RNA in Osteocytes Regulates Bone Formation through the Wnt/β-Catenin Signaling Pathway

The vast majority of transcribed RNAs are noncoding RNAs. Among noncoding RNAs, long noncoding RNAs (lncRNAs), which contain hundreds to thousands of bases, have received attention in many fields. The vast majority of the constituent cells in bone tissue are osteocytes, but their regulatory mechanisms are incompletely understood. Considering the wide range of potential contributions of lncRNAs to physiological processes and pathological conditions, we hypothesized that lncRNAs in osteocytes, which have not been reported, could be involved in bone metabolism. Here, we first isolated osteocytes from femurs of mice with osteocyte-specific GFP expression. Then, through RNA-sequencing, we identified osteocyte-specific lncRNAs and focused on a novel lncRNA, 9530026P05Rik (lncRNA953Rik), which strongly suppressed osteogenic differentiation. In the IDG-SW3 osteocyte line with lncRNA953Rik overexpression, the expression of Osterix and its downstream genes was reduced. RNA pull-down and subsequent LC-MS/MS analysis revealed that lncRNA953Rik bound the nuclear protein CCAR2. We demonstrated that CCAR2 promoted Wnt/β-catenin signaling and that lncRNA953Rik inhibited this pathway. lncRNA953Rik sequestered CCAR2 from HDAC1, leading to deacetylation of H3K27 in the Osterix promoter and consequent transcriptional downregulation of Osterix. This research is the first to clarify the role of a lncRNA in osteocytes. Our findings can pave the way for novel therapeutic options targeting lncRNAs in osteocytes to treat bone metabolic diseases such as osteoporosis.

HNF4α isoforms: the fraternal twin master regulators of liver function

In the more than 30 years since the purification and cloning of Hepatocyte Nuclear Factor 4 (HNF4α), considerable insight into its role in liver function has been gleaned from its target genes and mouse experiments. HNF4α plays a key role in lipid and glucose metabolism and intersects with not just diabetes and circadian rhythms but also with liver cancer, although much remains to be elucidated about those interactions. Similarly, while we are beginning to elucidate the role of the isoforms expressed from its two promoters, we know little about the alternatively spliced variants in other portions of the protein and their impact on the 1000-plus HNF4α target genes. This review will address how HNF4α came to be called the master regulator of liver-specific gene expression with a focus on its role in basic metabolism, the contributions of the various isoforms and the intriguing intersection with the circadian clock.

Whole Blood Expression Levels of Long Noncoding RNAs: HOTAIRM1, GAS5, MZF1-AS1, and OIP5-AS1 as Biomarkers in Adolescents with Obesity-Related Asthma

Asthma is a heterogeneous entity encompassing distinct endotypes and varying phenotypes, characterized by common clinical manifestations, such as shortness of breath, wheezing, and variable airflow obstruction. Two major asthma endotypes based on molecular patterns are described: type 2 endotype (allergic-asthma) and T2 low endotype (obesity-related asthma). Long noncoding RNAs (lncRNAs) are transcripts of more than 200 nucleotides in length, currently involved in many diverse biological functions, such as chromatin remodeling, gene transcription, protein transport, and microRNA processing. Despite the efforts to accurately classify and discriminate all the asthma endotypes and phenotypes, if long noncoding RNAs could play a role as biomarkers in allergic asthmatic and adolescent obesity-related asthma, adolescents remain unknown. To compare expression levels of lncRNAs: HOTAIRM1, OIP5-AS1, MZF1-AS1, and GAS5 from whole blood of Healthy Adolescents (HA), Obese adolescents (O), allergic asthmatic adolescents (AA) and Obesity-related asthma adolescents (OA). We measured and compared expression levels from the whole blood of the groups mentioned above through RT-q-PCR. We found differentially expressed levels of these lncRNAs between the groups of interest. In addition, we found a discriminative value of previously mentioned lncRNAs between studied groups. Finally, we generated an interaction network through bioinformatics. Expression levels of OIP5-AS1, MZF1-AS1, HOTAIRM1, and GAS5 in whole blood from the healthy adolescent population, obese adolescents, allergic asthma adolescents, and obesity-related asthma adolescents are differently expressed. Moreover, these lncRNAs could act as molecular biomarkers that help to discriminate between all studied groups, probably through molecular mechanisms with several genes and miRNAs implicated.