miR-1224-5p Enhances Hepatic Lipogenesis by Targeting Adenosine Monophosphate-Activated Protein Kinase α1 in Male Mice

Bioinformatics analysis of ferroptosis-related genes and immune cell infiltration in non-alcoholic fatty liver disease

BACKGROUND

The morbidity and mortality rates of patients with non-alcoholic fatty liver disease (NAFLD) have been steadily increasing in recent years. Previous studies have confirmed the important role of ferroptosis in NAFLD development; however, the precise mechanism through which ferroptosis influences NAFLD occurrence remains unclear. The present study aimed to identify and validate ferroptosis-related genes involved in NAFLD pathogenesis and to investigate the underlying molecular mechanisms of NAFLD.

METHODS

We downloaded microarray datasets GSE72756 and GSE24807 to identify differentially expressed genes (DEGs) between samples from healthy individuals and patients with NAFLD. From these DEGs, we extracted ferroptosis-related DEGs. GSE89632, another microarray dataset, was used to validate the expression of ferroptosis-related genes. A protein-protein interaction (PPI) network of ferroptosis-related genes was then constructed. The target genes were also subjected to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. Finally, competing endogenous RNA networks were constructed. We used the CIBERSORT package to evaluate the infiltration of immune cells infiltration in NAFLD.

RESULTS

Five ferroptosis-related genes (SCP2, MUC1, DPP4, SLC1A4, and TF) were identified as promising diagnostic biomarkers for NAFLD. Enrichment analyses revealed that these genes are mainly involved in metabolic processes. NEAT1-miR-1224-5p-SCP2, NEAT1-miR-485-5p-MUC1, MALAT1-miR-485-5p-MUC1, and CNOT6-miR-145-5p-SLC1A4 are likely to be the potential RNA regulatory pathways that affect NAFLD development. Principal component analysis indicated significant differences in immune cell infiltration between the two groups.

CONCLUSIONS

This study identified five ferroptosis-related genes as potential biomarkers for diagnosing NAFLD. The correlations between the expression of ferroptosis-related genes and immune cell infiltration might shed light on the study of the molecular mechanism underlying NAFLD development.

Zinc Improves Semen Parameters in High-Fat Diet-Induced Male Rats by Regulating the Expression of LncRNA in Testis Tissue

This study aimed to identify differentially expressed LncRNAs in testis tissue of male rats induced by high-fat diet and their changes after zinc supplementation, by constructing a high-fat feeding rat model, and then supplemented with zinc, and observed the expression of LncRNA in three groups of normal, high-fat fed, and zinc-intervened rats. Experimental studies show that the semen parameters of male rats with high-fat diet were decreased but recovered after zinc supplementation, and the related LncRNA also changed. Zinc may improve the high-fat diet-induced reduction of semen parameters by changing the expression of related LncRNA.

MicroRNA regulation of AMPK in nonalcoholic fatty liver disease

Obesity-associated nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease and is the leading cause of liver failure and death. The function of AMP-activated protein kinase (AMPK), a master energy sensor, is aberrantly reduced in NAFLD, but the underlying mechanisms are not fully understood. Increasing evidence indicates that aberrantly expressed microRNAs (miRs) are associated with impaired AMPK function in obesity and NAFLD. In this review, we discuss the emerging evidence that miRs have a role in reducing AMPK activity in NAFLD and nonalcoholic steatohepatitis (NASH), a severe form of NAFLD. We also discuss the underlying mechanisms of the aberrant expression of miRs that can negatively impact AMPK, as well as the therapeutic potential of targeting the miR-AMPK pathway for NAFLD/NASH.

GAS5 protects against nonalcoholic fatty liver disease via miR-28a-5p/MARCH7/NLRP3 axis-mediated pyroptosis

Nonalcoholic fatty liver disease (NAFLD) is characterised by hepatic steatosis, inflammation, and insulin resistance. The role of long noncoding RNA (lncRNA)-regulated pyroptosis in NAFLD development remains largely unknown. This study aimed to investigate whether NAFLD development is controlled by lncRNA growth-arrest specific transcript 5 (GAS5)/miR-28a-5p/membrane associated ring-CH-type finger 7 (MARCH7)-mediated pyroptosis using in vivo and in vitro models. First, GAS5 expression was decreased but miR-28a-5p expression was increased in the livers of NAFLD patients, high-fat diet (HFD)-fed mice and leptin-deficient obese (Ob/Ob) mice. Furthermore, GAS5 suppressed while miR-28a-5p promoted NAFLD development, and overexpression of miR-28a-5p reversed the GAS5 overexpression-induced attenuation of NAFLD. Mechanistically, GAS5 served as a sponge of miR-28a-5p, and miR-28a-5p enhanced pyroptosis by targeting the 3' untranslated region (UTR) of the E3 ligase MARCH7 during NAFLD development. MARCH7 interacted with the NOD-like receptor protein 3 (NLRP3) protein, resulting in proteasomal degradation of NLRP3 to inhibit pyroptosis. As expected, MARCH7 knockdown abolished the miR-28a-5p knockdown-induced inhibition of NAFLD development, and the ubiquitin E3 ligase-inactive mutant (W589A/I556A) of MARCH7 failed to inhibit NAFLD development. In conclusion, GAS5 protected against NAFLD development by binding to miR-28a-5p, miR-28a-5p promoted NAFLD development by targeting MARCH7, and MARCH7 ameliorated NAFLD by suppressing NLRP3-mediated pyroptosis. The GAS5/miR-28a-5p/MARCH7/NLRP3 axis plays an important role in NAFLD progression, and it might be a biomarker for NAFLD.

Therapeutic Effects of microRNAs on Nonalcoholic Fatty Liver Disease (NAFLD) and Nonalcoholic Steatohepatitis (NASH): A Systematic Review and Meta-Analysis

Nonalcoholic fatty liver disease (NAFLD) has emerged as a global health problem that affects people even at young ages due to unhealthy lifestyles. Without intervention, NAFLD will develop into nonalcoholic steatohepatitis (NASH) and eventually liver cirrhosis and hepatocellular carcinoma. Although lifestyle interventions are therapeutic, effective implementation remains challenging. In the efforts to establish effective treatment for NAFLD/NASH, microRNA (miRNA)-based therapies began to evolve in the last decade. Therefore, this systematic review aims to summarize current knowledge on the promising miRNA-based approaches in NAFLD/NASH therapies. A current systematic evaluation and a meta-analysis were conducted according to the PRISMA statement. In addition, a comprehensive exploration of PubMed, Cochrane, and Scopus databases was conducted to perform article searches. A total of 56 different miRNAs were reported as potential therapeutic agents in these studies. miRNA-34a antagonist/inhibitor was found to be the most studied variant (n = 7), and it significantly improved the hepatic total cholesterol, total triglyceride, Aspartate Aminotransferase (AST), and Alanine Transaminase (ALT) levels based on a meta-analysis. The biological processes mediated by these miRNAs involved hepatic fat accumulation, inflammation, and fibrosis. miRNAs have shown enormous therapeutic potential in the management of NAFLD/NASH, wherein miRNA-34a antagonist has been found to be an exceptional potential agent for the treatment of NAFLD/NASH.

Exosomes and lipid metabolism in metabolic and cardiovascular disorders

PURPOSE OF REVIEW

Exosomes are lipid-bound particles that carry lipids, protein, and nucleic acid and affect cellular function. This review highlights the current knowledge on the crosstalk between exosomes and lipid metabolism and their impact on cardiometabolic disease.

RECENT FINDINGS

Recent studies revealed that lipids and lipid metabolizing enzymes are important for exosome biogenesis and internalization and conversely how exosomes affect lipid metabolism, secretion, and degradation. The interplay between exosomes and lipid metabolism affects disease pathophysiology. More importantly, exosomes and lipids might function as biomarkers for diagnosis and prognosis or possibly therapies.

SUMMARY

Recent advances in our understanding of exosomes and lipid metabolism have implications for our understanding of normal cellular and physiological functions as well as disease pathogenesis. Exosome and lipid metabolism have implications in novel diagnostic tests and treatments of cardiometabolic disease.

CircNUFIP2 overexpression induces GDF11 to ameliorate oxygen-glucose deprivation-induced hippocampal neuron cell apoptosis and oxidative stress after cerebral ischemia

Background Previous data have indicated the regulation of circular RNA (circRNA) toward cerebral ischemia. This study aims to reveal the effects of circNUFIP2 on cerebral ischemia and the underlying mechanism. Methods Oxygen-glucose deprivation (OGD) hippocampal neuron (HT22) cell model and middle cerebral artery occlusion (MCAO) mouse model were used for this study. The expression of circRNA nuclear FMR1 interacting protein 2 (circNUFIP2), microRNA-1224-5p (miR-1224-5p) and growth differentiation factor 11 (GDF11) was detected by quantitative real-time polymerase-chain reaction. Protein expression was checked by Western blotting. The binding relationships among circNUFIP2, miR-1224-5p and GDF11 were identified by dual-luciferase reporter assay, RNA pull-down assay, and RNA immunoprecipitation assay. Cell proliferation and apoptosis were investigated by 5-Ethynyl-29-deoxyuridine and flow cytometry analysis, respectively. Results CircNUFIP2 and GDF11 expression were decreased, but miR-1224-5p was increased in OGD-treated HT22 cells when compared with their expression in control groups. OGD treatment inhibited HT22 cell proliferation but induced cell apoptosis and oxidative stress; however, these effects were attenuated after circNUFIP2 overexpression. Also, circNUFIP2 upregulation assuaged the cerebral infarction of MCAO mice. Besides, circNUFIP2 bound to miR-1224-5p and mediated OGD-induced HT22 cell damage through miR-1224-5p. Meanwhile, knockdown of GDF11, a target gene of miR-1224-5p, relieved miR-1224-5p depletion-caused effects in OGD-treated HT22 cells. Furthermore, circNUFIP2 regulated GDF11 expression by interacting with miR-1224-5p. Conclusion CircNUFIP2 overexpression protected neuron cells against cerebral ischemia-induced damage, at least in part, by the miR-1224-5p/GDF11 pathway, providing a possible target for the therapy of cerebral ischemic stroke.

Advances in metformin for the treatment of non-alcoholic fatty liver disease in children

INTRODUCTION

The increased economic and social burdens for NAFLD worldwide make treating such a disease a significant public health issue. Metformin, a kind of insulin sensitizer generally used to treat type 2 diabetes, has been recently found to have efficacy on children's NAFLD in various areas such as glucolipid metabolism, intestinal bacterial metabolism, oxidative stress, and anti-inflammatory response. This article aims to provide an overview of the possible mechanisms of NAFLD in children and the potential therapeutic application of metformin.

AREAS COVERED

The Cochrane Library, PubMed, Scopus, and EMBASE database was systematically searched on 12 April 2022, using the keywords metformin; non-alcoholic fatty liver disease; and children to identify similar studies. An additional search for recently published research was performed in June 2020.

EXPERT OPINION

Although metformin has been proved to have an excellent therapeutic effect on children's NAFLD; we can still explore its potential impacts and mechanisms from different angles, such as combined medication. At the same time, we should also pay attention to its side effects.

Adipocytes-derived exosomal microRNA-1224 inhibits M2 macrophage polarization in obesity-induced adipose tissue inflammation via MSI2-mediated Wnt/β-catenin axis

SCOPE

Phenotypic switch of macrophage polarization in adipose tissue has been associated with obesity-induced adipose tissue inflammation (OATI). Therefore, we aimed to explore the possible mechanism of adipocytes-derived exosomes (ADEs) carrying microRNA-1224 (miR-1224) in M2 macrophage polarization of OATI.

METHODS AND RESULTS

We developed miR-1224-knockout (miR-1224-KO) mice for this study, and isolated primary adipocytes from high-fat diet (HFD) or normal diet (SD)-fed mice. ADEs were extracted and cocultured with bone marrow-derived macrophages (BMDMs). The macrophagic crown-like structures (CLS) and M1 and M2 phenotype macrophages in epididymal white adipose tissue (epiWAT) were observed by immunohistochemistry and flow cytometry. The obtained data indicated that miR-1224 was highly expressed in adipose tissues and adipocytes of obese mice. miR-1224 knockout decreased CLS number and increased M2 macrophages polarization in epiWAT. In addition, miR-1224 could be transferred to BMDMs via ADEs, which targeted musashi RNA binding protein 2 (MSI2) expression and inactivated Wnt/β-catenin pathway, inhibiting macrophage M2 polarization and promoting inflammatory factor release.

CONCLUSION

Exosomal miR-1224 derived by adipocytes targets MSI2 and blocks the Wnt/β-catenin pathway, which inhibits macrophage M2 polarization and promotes inflammatory factor release, ultimately promoting OATI. This article is protected by copyright. All rights reserved.

MicroRNAs in obesity, sarcopenia, and commonalities for sarcopenic obesity: a systematic review

Sarcopenic obesity is a distinct condition of sarcopenia in the context of obesity, with the cumulative health risks of both phenotypes. Differential expression of microRNAs (miRNAs) has been reported separately in people with obesity and sarcopenia and may play a role in the pathogenesis of sarcopenic obesity. However, this has not been explored to date. This study aimed to identify differentially expressed miRNAs reported in serum, plasma, and skeletal muscle of people with obesity and sarcopenia and whether there are any commonalities between these conditions. We performed a systematic review on Embase and MEDLINE (PROSPERO, CRD42020224486) for differentially expressed miRNAs (fold change >1.5 or P-value <0.05) in (i) sarcopenia or frailty and (ii) obesity or metabolic syndrome. The functions and targets of miRNAs commonly changed in both conditions, in the same direction, were searched using PubMed. Following deduplication, 247 obesity and 42 sarcopenia studies were identified for full-text screening. Screening identified 36 obesity and 6 sarcopenia studies for final inclusion. A total of 351 miRNAs were identified in obesity and 157 in sarcopenia. Fifty-five miRNAs were identified in both obesity and sarcopenia-by sample type, 48 were found in plasma and one each in serum and skeletal muscle. Twenty-four miRNAs were identified from 10 of the included studies as commonly changed in the same direction (22 in plasma and one each in serum and skeletal muscle) in obesity and sarcopenia. The majority of miRNA-validated targets identified in the literature search were members of the phosphoinositide 3-kinase/protein kinase B and transforming growth factor-β signalling pathways. The most common targets identified were insulin-like growth factor 1 (miR-424-5p, miR-483-3p, and miR-18b-5p) and members of the SMAD family (miR-483-3p, miR-92a-3p, and miR-424-5p). The majority of commonly changed miRNAs were involved in protein homeostasis, mitochondrial dynamics, determination of muscle fibre type, insulin resistance, and adipogenesis. Twenty-four miRNAs were identified as commonly dysregulated in obesity and sarcopenia with functions and targets implicated in the pathogenesis of sarcopenic obesity. Given the adverse health outcomes associated with sarcopenic obesity, understanding the pathogenesis underlying this phenotype has the potential to lead to effective screening, monitoring, or treatment strategies. Further research is now required to confirm whether these miRNAs are differentially expressed in older adults with sarcopenic obesity.

Maternal undernutrition modulates hepatic MicroRNAs expression in the early life of offspring

Emerging studies revealed that a poor intrauterine environment elicited by maternal nutrient restriction (MNR) is associated with an increased risk of metabolic diseases in adulthood. Previous research has shown that microRNAs (miRNAs) exert pivotal roles in modulating molecular pathways involved in disease pathogenesis and progression. In this respect, we herein examined miRNA profiles in samples of liver from offspring whose mothers were fed either with a 50% food-restricted diet or standard laboratory chow during pregnancy. Our findings enumerated that miR-181a, involved in lipid metabolism, was found to be downregulated in the liver of MNR offspring at 1 day of age when compared to that of control offspring. We also noted that overexpression of miR-181a reduced the lipid droplets after treatment with oleic acid for 48 h, which suppressed the expressions levels of SIRT1, FOXO1, KLF6 and PPARγ in BRL-3A cells, while the opposite results were observed with decreased expression of miR-181a. Furthermore, the luciferase reporter assay confirmed the direct interactions between miR-181a with KLF6 and SIRT1. In adults, the MNR offspring elucidated increased TG content, decreased expression of miR-181a, and increased expressions levels of SIRT1, FOXO1, KLF6, and PPARγ in liver tissues. Collectively, these findings provided novel evidence that MNR could regulate miRNAs expression, which might be related to lipid metabolism in MNR offspring.

Differentially Expressed miRNA-Gene Targets Related to Intramuscular Fat in Musculus Longissimus Dorsi of Charolais × Holstein F2-Crossbred Bulls

Intramuscular fat (IMF) is a meat quality indicator associated with taste and juiciness. IMF deposition, influenced by genetic and non-genetic factors, occurs through a transcriptionally coordinated process of adipogenesis. MicroRNAs (miRNAs) are transcriptional regulators of vital biological processes, including lipid metabolism and adipogenesis. However, in bovines, limited data on miRNA profiling and association with divergent intramuscular fat content, regulated exclusively by genetic parameters, have been reported. Here, a microarray experiment was performed to identify and characterize the miRNA expression pattern in the Musculus longissimus dorsi of F₂-cross (Charolais × German Holstein) bulls with high and low IMF. A total of 38 differentially expressed miRNAs (DE miRNAs), including 33 upregulated and 5 downregulated (corrected p-value ≤ 0.05, FC ≥ ±1.2), were reported. Among DE miRNAs, the upregulated miRNAs miR-105a/b, miR-695, miR-1193, miR-1284, miR-1287-5p, miR-3128, miR-3178, miR-3910, miR-4443, miR-4445 and miR-4745, and the downregulated miRNAs miR-877-5p, miR-4487 and miR-4706 were identified as novel fat deposition regulators. DE miRNAs were further analyzed, along with previously identified differentially expressed genes (DEGs) from the same samples and predicted target genes, using multiple bioinformatic approaches, including target prediction tools and co-expression networks, as well as Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment. We identified DE miRNAs and their gene targets associated with bovine intramuscular adipogenesis, and we provide a basis for further functional investigations.

MicroRNAs and other non-coding RNAs in adipose tissue and obesity: emerging roles as biomarkers and therapeutic targets

Obesity is a metabolic condition usually accompanied by insulin resistance (IR), type 2 diabetes (T2D), and dyslipidaemia, which is characterised by excessive fat accumulation and related to white adipose tissue (WAT) dysfunction. Enlargement of WAT is associated with a transcriptional alteration of coding and non-coding RNAs (ncRNAs). For many years, big efforts have focused on understanding protein-coding RNAs and their involvement in the regulation of adipocyte physiology and subsequent role in obesity. However, diverse findings have suggested that a dysfunctional adipocyte phenotype in obesity might be also dependent on specific alterations in the expression pattern of ncRNAs, such as miRNAs. The aim of this review is to update current knowledge on the physiological roles of miRNAs and other ncRNAs in adipose tissue function and their potential impact on obesity. Therefore, we examined their regulatory role on specific WAT features: adipogenesis, adipokine secretion, inflammation, glucose metabolism, lipolysis, lipogenesis, hypoxia and WAT browning. MiRNAs can be released to body fluids and can be transported (free or inside microvesicles) to other organs, where they might trigger metabolic effects in distant tissues, thus opening new possibilities to a potential use of miRNAs as biomarkers for diagnosis, prognosis, and personalisation of obesity treatment. Understanding the role of miRNAs also opens the possibility of using these molecules on individualised dietary strategies for precision weight management. MiRNAs should be envisaged as a future therapeutic approach given that miRNA levels could be modulated by synthetic molecules (f.i. miRNA mimics and inhibitors) and/or specific nutrients or bioactive compounds.