miR-34a/SIRT1/p53 is suppressed by ursodeoxycholic acid in the rat liver and activated by disease severity in human non-alcoholic fatty liver disease

The role of MDM2-p53 axis dysfunction in the hepatocellular carcinoma transformation

Liver cancer is the second most frequent cause of cancer-related death globally. The main histological subtype is hepatocellular carcinoma (HCC), which is derived from hepatocytes. According to the epidemiologic studies, the most important risk factors of HCC are chronic viral infections (HBV, HCV, and HIV) and metabolic disease (metabolic syndrome). Interestingly, these carcinogenic factors that contributed to HCC are associated with MDM2-p53 axis dysfunction, which presented with inactivation of p53 and overactivation of MDM2 (a transcriptional target and negative regulator of p53). Mechanically, the homeostasis of MDM2-p53 feedback loop plays an important role in controlling the initiation and progression of HCC, which has been found to be dysregulated in HCC tissues. To maintain long-term survival in hepatocytes, hepatitis viruses have lots of ways to destroy the defense strategies of hepatocytes by inducing TP53 mutation and silencing, promoting MDM2 overexpression, accelerating p53 degradation, and stabilizing MDM2. As a result, genetic instability, chronic ER stress, oxidative stress, energy metabolism switch, and abnormalities in antitumor genes can be induced, all of which might promote hepatocytes' transformation into hepatoma cells. In addition, abnormal proliferative hepatocytes and precancerous cells cannot be killed, because of hepatitis viruses-mediated exhaustion of Kupffer cells and hepatic stellate cells (HSCs) and CD4+T cells by disrupting their MDM2-p53 axis. Moreover, inefficiency of hepatic immune response can be further aggravated when hepatitis viruses co-infected with HIV. Unlike with chronic viral infections, MDM2-p53 axis might play a dual role in glucolipid metabolism of hepatocytes, which presented with enhancing glucolipid catabolism, but promoting hepatocyte injury at the early and late stages of glucolipid metabolism disorder. Oxidative stress, fatty degeneration, and abnormal cell growth can be detected in hepatocytes that were suffering from glucolipid metabolism disorder, and all of which could contribute to HCC initiation. In this review, we focus on the current studies of the MDM2-p53 axis in HCC, and specifically discuss the impact of MDM2-p53 axis dysfunction by viral infection and metabolic disease in the transformation of normal hepatocytes into hepatoma cells. We also discuss the therapeutic avenues and potential targets that are being developed to normalize the MDM2-p53 axis in HCC.

Changes in structure and flexibility of p53 TAD2 upon binding to p300 Taz2

p53 is a transcription factor with intrinsically disordered regions that plays an essential role in many cellular processes. As a tumor suppressor, the dysfunction of p53 causes various cancers. p53 can be activated by binding with cofactors in the cell due to stresses or DNA damages. The N-terminal transactivation domain (TAD) of p53 can regulate cell apoptosis by interacting with its binding partners, such as the transcriptional adaptor zinc-binding 2 (Taz2) domain of p300, and cofactors, i.e. cyclic-AMP response element-binding protein (CREB)-binding protein (CBP). The experimentally solved structure of p300 Taz2 and p53 TAD2 has provided insights into the interactions that potentially lead to the structural changes of p53 TAD2 and stabilize the complex. To explore the structural changes as well as the residues that lead to such changes from an isolated state to a bound state in p53 TAD2, we used all-atom molecular dynamics (MD) to simulate two different systems: (1) the p300 Taz2–p53 TAD2 complex and (2) isolated p53 TAD2 (residues 35–59). Although still largely unstructured, residues across the p53 TAD2 contribute significantly to stabilizing the binding between p300 Taz2 and p53 TAD2. Our results suggest that the binding affinity of the p300 Taz2–p53 TAD2 complex originates from hydrophobic and electrostatic interactions. The results are in agreement with previous reports and experimental data. By comparing the two simulated systems, our results not only demonstrate the structural changes of p53 TAD2 after binding with Taz2 but also identify the key residues leading to such changes. We also identify the critical residues that can provide insight into the interaction network between p300 Taz2 and p53 TAD2.

Efficacy of serum miRNA test as a non-invasive method to diagnose nonalcoholic steatohepatitis: a systematic review and meta-analysis

Background

Nonalcoholic steatohepatitis (NASH) is a key turning point during the progression of nonalcoholic fatty liver disease (NAFLD). Recent studies have shown that serum miRNA tests may be effective in the diagnosis of NAFLD. We conducted a meta-analysis to assess the evidence for the diagnostic efficacy of serum miRNAs in patients with NAFLD and its subtype, NASH, in particular.

Methods

After a systematic review, sensitivity, specificity, and area under the receiver operating characteristics curve (AUROC) were pooled to determine the efficacy of serum miRNA test for the diagnosis of NAFLD and NASH. Clinical utility was evaluated by Fagan’s nomogram and likelihood ratio scattergram. Heterogeneity was evaluated by subgroup analysis and meta-regression. Publication bias was detected by Deeks’ funnel plot.

Results

We included 27 trials containing 1775 NAFLD patients (including simple steatosis and NASH) and 586 NASH patients. For NAFLD vs NASH, the pooled sensitivity, specificity, and AUROC were (0.71 vs. 0.74), (0.76 vs. 0.85) and (0.80 vs. 0.86), respectively. Serum miRNA had high accuracy for distinguishing NASH from simple steatosis, with an AUROC of 0.91. Among the most commonly studied serum miRNAs, miRNA-34a showed moderate diagnostic accuracy for NAFLD and the lowest heterogeneity (sensitivity I² = 5.73%, specificity I² = 33.16%, AUROC = 0.85). According to subgroup analysis and meta-regression, a lower BMI (< 30 kg/m²) might be a crucial source of heterogeneity.

Conclusions

As a novel non-invasive method, serum miRNA test exhibited robust diagnostic efficacy for NASH. Among these well-studied miRNAs, miRNA-34a was more available for diagnosis. Diagnosis of NAFLD by serum miRNA is more likely to be accurate in patients with BMI ≥ 30 kg/m².

Epigenetic contribution to obesity

Obesity is a worldwide epidemic and contributes to global morbidity and mortality mediated via the development of nonalcoholic fatty liver disease (NAFLD), type 2 diabetes (T2D), cardiovascular (CVD) and other diseases. It is a consequence of an elevated caloric intake, a sedentary lifestyle and a genetic as well as an epigenetic predisposition. This review summarizes changes in DNA methylation and microRNAs identified in blood cells and different tissues in obese human and rodent models. It includes information on epigenetic alterations which occur in response to fat-enriched diets, exercise and metabolic surgery and discusses the potential of interventions to reverse epigenetic modifications.

The Epigenetic Drug Discovery Landscape for Metabolic-associated Fatty Liver Disease

Despite decades of research, effective therapies for metabolic (dysfunction)-associated fatty liver disease (MAFLD) are lacking. An increasing body of evidence suggests that epigenetic dysregulation is frequent in MAFLD, and orchestrates many aspects of its development and progression. Furthermore, the high plasticity of epigenetic modifications in response to environmental cues renders epigenetics a novel area for therapeutic drug discovery. Over recent years, several epigenetics-based drugs and diagnostic biomarkers have entered clinical development and/or obtained regulatory approval. Here, we review recent advances in our understanding of epigenetic regulation and programming during MAFLD, including DNA methylation, histone modifications, chromatin remodelling, transcriptional control, and noncoding (nc)RNAs. We also discuss the potential translational implications and challenges of epigenetics in the context of MAFLD.

Processes exacerbating apoptosis in non-alcoholic steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) is a significant public health concern, owing to its high prevalence, progressive nature and lack of effective medical therapies. NAFLD is a complex and multifactorial disease involving the progressive and concerted action of factors that contribute to the development of liver inflammation and eventually fibrosis. Here, we summarize fundamental molecular mechanisms underlying the pathogenesis of non-alcoholic steatohepatitis (NASH), how they are interrelated and possible translation to clinical applications. We focus on processes triggering and exacerbating apoptotic signalling in the liver of NAFLD patients and their metabolic and pathological implications. Indeed, liver injury and inflammation are cardinal histopathological features of NASH, a duo in which derailment of apoptosis is of paramount importance. In turn, the liver houses a very high number of mitochondria, crucial metabolic unifiers of both extrinsic and intrinsic signals that converge in apoptosis activation. The role of lifestyle options is also dissected, highlighting the management of modifiable risk factors, such as obesity and harmful alcohol consumption, influencing apoptosis signalling in the liver and ultimately NAFLD progression. Integrating NAFLD-associated pathologic mechanisms in the cell death context could provide clues for a more profound understating of the disease and pave the way for novel rational therapies.

Identification of MicroRNA-Target Gene-Transcription Factor Regulatory Networks in Colorectal Adenoma Using Microarray Expression Data

Objective

The aim of the study was to find the key genes, microRNAs (miRNAs) and transcription factors (TFs) and construct miRNA-target gene-TF regulatory networks to investigate the underlying molecular mechanism in colorectal adenoma (CRA).

Methods

Four mRNA expression datasets and one miRNA expression dataset were downloaded from Gene Expression Omnibus (GEO) database. Differentially expressed miRNAs (DEMs) and differentially expressed genes (DEGs) were identified between CRA and normal samples. Moreover, functional enrichment analysis for DEGs was carried out utilizing the Cytoscape-plugin, known as ClueGO. These DEGs were mapped to STRING database to construct a protein-protein interaction (PPI) network. Then, a miRNA-target gene regulatory network was established to screen key DEMs. In addition, similar workflow of the analyses were also performed comparing the CRC samples with CRA ones to screen key DEMs. Finally, miRNA-target gene-TF regulatory networks were constructed for these key DEMs using iRegulon plug-in in Cytoscape.

Results

We identified 514 DEGs and 167 DEMs in CRA samples compared to healthy samples. Functional enrichment analysis revealed that these DEGs were significantly enriched in several terms and pathways, such as regulation of cell migration and bile secretion pathway. A PPI network was constructed including 325 nodes as well as 890 edges. A total of 59 DEGs and 65 DEMs were identified in CRC samples compared to CRA ones. In addition, Two key DEMs in CRA samples compared to healthy samples were identified, such as hsa-miR-34a and hsa-miR-96. One key DEM, hsa-miR-29c, which was identified when we compared the differentially expressed molecules found in the comparison CRA versus normal samples to the ones obtained in the comparison CRC versus CRA, was also identified in CRC samples compared to CRA ones. The miRNA-target gene-TF regulatory networks for these key miRNAs included two TFs, one TF and five TFs, respectively.

Conclusion

These identified key genes, miRNA, TFs and miRNA-target gene-TF regulatory networks associated with CRA, to a certain degree, may provide some hints to enable us to better understand the underlying pathogenesis of CRA.

Differential Associations of Circulating MicroRNAs With Pathogenic Factors in NAFLD

Nonalcoholic fatty liver disease (NAFLD) is a heterogeneous disease driven by genetic and environmental factors. MicroRNAs (miRNAs) serve as pleiotropic post-transcriptional regulators of cellular pathways. Although several miRNAs have been associated with NAFLD and fibrosis, there are limited studies in humans examining their differential association with pathogenic factors or histological features of NAFLD. We examined the differential relationships of five of the best-described circulating microRNAs (miR-34a, miR-122, miR-191, miR-192, and miR-200a) with histological features and pathogenic factors of NAFLD. A cross-sectional study was conducted to examine the relationship between relative levels of circulating microRNAs standardized by z-scores and histological features of NAFLD, common NAFLD genetic polymorphisms, and insulin resistance measured by the enhanced lipoprotein insulin resistance index in 132 subjects with biopsy-proven NAFLD. We found that miR-34a, miR-122, miR-192, miR-200a, but not miR-191, strongly correlate with fibrosis in NAFLD by increases of 0.20 to 0.40 SD (P < 0.005) with each stage of fibrosis. In multivariate analysis, miR-34a, miR-122, and miR-192 levels are independently associated with hepatic steatosis and fibrosis, but not lobular inflammation or ballooning degeneration, whereas miR-200a is only associated with fibrosis. Among the four miRNAs, miR-34a, miR-122, and miR-192 are associated with pathogenic factors of NAFLD, including insulin resistance measured by eLP-IR, patatin-like phospholipase domain containing 3 I148M, and transmembrane 6 superfamily 2 (TM6SF2) E167K polymorphisms. In contrast, miR-200a is only associated with the TM6SF2 E167K variant. Finally, miR-34a has the strongest predictive value for various stages of fibrosis, with C-statistic approximates-combined predictive score for miRNAs. Conclusion: miR-34a, miR-122, miR-192, and miR-200a demonstrate strong associations with NAFLD severity by histology, but differential associations with pathogenic factors.

MiR-30b-5p regulates the lipid metabolism by targeting PPARGC1A in Huh-7 cell line

BACKGROUND

MiRNAs are a group of multifunctional non-coding RNAs which play an important role in the various physiological processes including the development of NAFLD. Recent studies have shown that miR-30b-5p tightly associated with the abnormal lipid metabolism in patients with NAFLD, but the detailed mechanism of miR-30b-5p in the lipid metabolism was remain unclear. The aim of this study was to investigate the effect of miR-30b-5p on the lipid metabolism in hepatocellular carcinoma Huh-7 cells.

MATERIAL AND METHODS

The correlation of intracellular fat content with the expression of miR-30b-5p in Huh-7 cells and HepG2 cells was investigated by treated cells with different concentrations of FFAs. The effect of miR-30b-5p on the lipid deposition in Huh-7 cells was tested by oil red O staining and TG concentrations measurement. qRT-PCR and western blot were used to investigate the lipid metabolism-related genes PPAR-α, SREBP-1, and GULT1 in miR-30b-5p overexpressed or inhibited Huh-7 cells. Target genes of miR-30b-5p were predicted using starBase, miRDB, and TargetScan databases and verified by qRT-PCR and western blot.

RESULTS

The expression of miR-30b-5p was significant decreased in the FFAs treated Huh-7 cells and HepG2 cells. Overexpressing miR-30b-5p in Huh-7 cells decreased the number and size of lipid droplets and intracellular TG concentrations in Huh-7 cells. Expression of fatty acid oxidation related gene PPAR-α was increased and expression of lipid synthesis related gene SREBP-1 was decreased in the miR-30b-5p overexpressed Huh-7 cells. In addition, miR-30b-5p regulates the intracellular lipid metabolism by targeting PPARGC1A.

CONCLUSIONS

Overexpression of miR-30b-5p could reduce the intracellular fat deposition in Huh-7 cells, and miR-30b-5p might regulate the intracellular lipid metabolism by targeting the PPARGC1A in Huh-7 cells.

Modulation of the hepatic expression of miR-33 and miR-34a possibly mediates the metabolic effects of estrogen in ovariectomized female rats

Estrogen and the estrogen receptors (ERs) are well-known regulators of several aspects of glucose and lipid metabolism. Meanwhile, the underlying mechanistic role of estrogens in regulating metabolic health remains largely unknown. Hence, the study was designed to tackle the possible contribution of the hepatic expression of miR-33, miR-21 and miR-34a and their target genes as the underlying mechanism of the metabolic effects of estrogen in ovariectomized rats. Forty female rats were ovariectomized (OVX), treated with estrogen and/or fulvestrant for 28 days and compared with untreated or treated sham operated rats. Estradiol amended the metabolic abnormalities in the OVX rats, witnessed by decreasing blood sugar, insulin and HOMA-IR as well as correcting the disrupted serum and hepatic lipids. Estradiol increased the hepatic expression of miR-33 and inhibited that of miR-34a and miR-21, leading to adjusting the gene expression and the protein level of their targets, sterol regulatory element-binding proteins-1c (SREBP-1c), fatty acid synthase (FASN), high mobility group (HMG) Box Transcription Factor 1 (HBP1) and Sirtuin 1 (SIRT1), receptively. However, estrogen had no significant effects on HBP1 protein. These effects were almost completely inhibited by fulvestrant, an estrogen receptor blocker, to the extent that fulvestrant had similar metabolic disorders to that of ovariectomization. In conclusion, estrogen replacement therapy in OVX females significantly ameliorated the metabolic derangements of insulin resistance, dyslipidemia and hepatic fat accumulation possibly via corrections of hepatic expression of miR-33 and miR-34a; effects that were mediated through the receptor-mediated signaling of ERs as confirmed by fulvestrant.

Ursodeoxycholic acid inhibits intimal hyperplasia, vascular smooth muscle cell excessive proliferation, migration via blocking miR-21/PTEN/AKT/mTOR signaling pathway

Excessive migration and proliferation of vascular smooth muscle cells (VSMCs) are critical cellular events that lead to intimal hyperplasia in atherosclerosis and restenosis. In this study, we investigated the protective effects of ursodeoxycholic acid (UDCA) on intimal hyperplasia and VSMC proliferation and migration, and the underlying mechanisms by which these events occur. A rat unilateral carotid artery was ligated to induce vascular injury and the microRNA (miRNA) expression profiles were determined using miRNA microarray analysis. We observed that UDCA significantly reduced the degree of intimal hyperplasia and induced miR-21 dysregulation. Restoration of miR-21 by agomir-miR-21 reversed the protective effects of UDCA on intimal hyperplasia and proliferation in vivo. In vitro, UDCA suppressed PDGF-BB-induced VSMC proliferation, invasion and migration in a dose-dependent manner, whereas the suppressive effect of UDCA was abrogated by overexpression of miR-21 in PDGF-BB-incubated VSMCs. Furthermore, we identified that miR-21 in VSMCs targeted the phosphatase and tensin homolog (PTEN), a tumor suppressor gene, negatively modulated the AKT/mTOR pathway. More importantly, we observed that that UDCA suppressed AKT/mTOR signaling pathway in the carotid artery injury model, whereas this pathway was reactivated by overexpression of miR-21. Taken together, our findings indicated that UDCA inhibited intimal hyperplasia and VSMCs excessive migration and proliferation via blocking miR-21/PTEN/AKT/mTOR signaling pathway, which suggests that UDCA may be a promising candidate for the therapy of atherosclerosis.

[The Diagnostic Importance of Circulating MicroRNA for Non-Alcoholic Fatty Liver Disease (review of literature).]

Non-alcoholic fatty liver disease (NAFLD) is one of the leading causes of chronic liver diseases in the world. The biopsy is required to confirm the diagnosis but due to its invasiveness, this procedure is not suitable for the massive screening. There are laboratory criteria of primary medical examination of the patients who are suspected to have NAFLD that allow diagnosing the pathological process, but these criteria do not comply with clinicians' requirements. At the same time, it is crucial to identify the patients in the initial stages of NAFLD. Recently, the attention of the scientists was concentrated on the research of the mechanism of NAFLD development and new diagnostic approaches. Accumulating results of this research show that NAFLD development is regulated with epigenetic factors, including microRNAs family (microRNA, miR), that may have high diagnostic and prognostic value. In this review, data extracted from PubMed are used to discuss the potential role of microRNA in the liver lipid metabolism and fatty liver disease. The possibilities of micro RNA (miR-16, miR-21, miR-34a, miR-103, miR-122, miR-145, miR-192, and others) use as prospective biomarkers for low-invasive NAFLD diagnostic, evaluation of steatosis activity and fibrosis score and stages, and prognostic markers of the disease are reviewed. This research discusses the analytical characteristics, benefits and possible limitations of their use in the clinical practice. The preliminary data allow claiming that some microRNAs are extremely perspective low-invasive diagnostic instrument and further research is required to investigate the impact of certain microRNAs in the pathogenetic mechanism of NAFLD development.

miR-34a promotes liver fibrosis in patients with chronic hepatitis via mediating Sirt1/p53 signaling pathway

PURPOSE

This research aimed to explore the correlation between miR-34a expression in peripheral blood and clinical characteristics of patients with chronic hepatitis C (CHC) as well as the diagnostic and prognostic values of serum miR-34a in CHC.

METHODS

Serum samples of 41 CHC patients and 18 normal participants were collected to examine the expression levels of miR-34a using qRT-PCR. The changes of serum TBA, liver enzyme AST and ALT were also determined by enzyme colorimetry and rate method. The levels of serum fibrotic markers hyaluronic acid (HA), type III procollagen (PCIII), type IV collagen (IV-C) and laminin (LN) were detected by radioimmunoassay. Degree of liver fibrosis was examined by liver biopsy. Western blot analysis was used to investigate the expression of ac-p53, p53 and Sirt1 in the liver tissues of CHC patients.

RESULTS

MiR-34a was significantly increased in the serum of CHC patients than that in healthy participants, and serum miR-34a was correlated with liver fibrosis index. Serum TBA, AST and ALT levels, and AST/ALT ratios in patients with CHC were increased with increasing degree of fibrosis, and were positively associated with serum miR-34a. Furthermore, the liver tissues of CHC patients showed low Sirt1 protein expression and highly ac-p53 protein expression.

CONCLUSIONS

Serum miR-34a in patients with CHC could promote liver fibrosis through mediating the Sirt1/p53 pathway and might function as pivotal biomarker on the prognosis and diagnosis of CHC patients.

Anti-aging Effects of Calorie Restriction (CR) and CR Mimetics based on the Senoinflammation Concept

Chronic inflammation, a pervasive feature of the aging process, is defined by a continuous, multifarious, low-grade inflammatory response. It is a sustained and systemic phenomenon that aggravates aging and can lead to age-related chronic diseases. In recent years, our understanding of age-related chronic inflammation has advanced through a large number of investigations on aging and calorie restriction (CR). A broader view of age-related inflammation is the concept of senoinflammation, which has an outlook beyond the traditional view, as proposed in our previous work. In this review, we discuss the effects of CR on multiple phases of proinflammatory networks and inflammatory signaling pathways to elucidate the basic mechanism underlying aging. Based on studies on senoinflammation and CR, we recognized that senescence-associated secretory phenotype (SASP), which mainly comprises cytokines and chemokines, was significantly increased during aging, whereas it was suppressed during CR. Further, we recognized that cellular metabolic pathways were also dysregulated in aging; however, CR mimetics reversed these effects. These results further support and enhance our understanding of the novel concept of senoinflammation, which is related to the metabolic changes that occur in the aging process. Furthermore, a thorough elucidation of the effect of CR on senoinflammation will reveal key insights and allow possible interventions in aging mechanisms, thus contributing to the development of new therapies focused on improving health and longevity.

Pterostilbene Improves Hepatic Lipid Accumulation via the MiR-34a/Sirt1/SREBP-1 Pathway in Fructose-Fed Rats

High fructose intake promotes hepatic lipid accumulation. Pterostilbene, a natural analogue of resveratrol found in diet berries, exhibits a hepatoprotective property. Here, we studied the protection by pterostilbene against fructose-induced hepatic lipid accumulation and explored its possible mechanism. We observed a high expression of microRNA-34a (miR-34a, P < 0.05) and a low expression of its target, sirtuin1 (Sirt1, mRNA: P < 0.01; protein: P < 0.001), with the overactivation of downstream sterol regulatory element-binding protein-1 (SREBP-1) lipogenic pathway (nuclear SREBP-1 protein: P < 0.05; FAS and SCD1 mRNA: P < 0.01), in rat livers, as well as BRL-3A and HepG2 cells, stimulated by fructose. More interestingly, pterostilbene recovered the fructose-disturbed miR-34a expression (0.3-0.5-fold vs fructose control, P < 0.05), Sirt1 protein level (1.2- to 1.5-fold vs fructose control, P < 0.05), and SREBP-1 lipogenic pathway, resulting in significant amelioration of hepatocyte lipid accumulation in animal [hepatic triglyceride and total cholesterol (TG&TC) mg/g·wet tissue: 4.90 ± 0.19, 5.23 ± 0.16, 5.20 ± 0.29 vs fructose control 9.73 ± 1.06, P < 0.001; 3.18 ± 0.30, 3.31 ± 0.39, 3.37 ± 0.47 vs 5.67 ± 0.28, P < 0.001] and cell models (BRL-3A TG&TC mmol/g·protein: 0.123 ± 0.011 vs 0.177 ± 0.004, P < 0.001; 0.169 ± 0.011 vs 0.202 ± 0.008, P < 0.05; HepG2: 0.257 ± 0.005 vs 0.303 ± 0.016, P < 0.05; 0.143 ± 0.004 vs 0.201 ± 0.008, P < 0.001). These results provide the experimental evidence supporting the anti-lipogenic effect of pterostilbene against fructose-induced hepatic lipid accumulation via modulating the miR-34a/Sirt1/SREBP-1 pathway.

Purple sweet potato color protects against hepatocyte apoptosis through Sirt1 activation in high-fat-diet-treated mice

Background

Recent evidence indicates that the inhibition of hepatocyte apoptosis is possible to develop a potential therapeutic strategy for nonalcoholic fatty liver disease (NAFLD). Our previous work suggested that purple sweet potato color (PSPC), a class of naturally occurring anthocyanins, effectively improved many features of high-fat diet (HFD)-induced NAFLD. However, whether PSPC ameliorates HFD-induced hepatocyte apoptosis has never been investigated.

Objective

Here we investigated the effects of PSPC on HFD-induced hepatic apoptosis and the mechanisms underlying these effects.

Design

Mice were divided into four groups: Control group, HFD group, HFD + PSPC group and PSPC group. PSPC was administered by daily oral gavage at doses of 700 mg/kg/day for 20 weeks. EX-527 (a SirT1-selective inhibitor) and Sirt1 siRNA were used to demonstrate the Sirt1 dependence of PSPC-mediated effects on apoptotic and survival signaling pathways in vivo and in vitro.

Results

Our results showed that PSPC reduced body weights, hepatic triglyceride contents, histopathological lesions and serum ALT levels in a mouse model of NAFLD induced by HFD. Furthermore, PSPC attenuated HFD-induced hepatocyte apoptosis ratio from 7.27 ± 0.92% to 1.79 ± 0.27% in mouse livers, which is insignificant compared with that of controls. Moreover, PSPC activated Sirt1 by boosting NAD⁺ level in HFD-treated mouse livers. Furthermore, PSPC promoted Sirt1-dependent suppression of P53-mediated apoptotic signaling and activation of Akt survival signaling pathway in HFD-treated mouse livers, which was confirmed by EX527 treatment. Moreover, Sirt1 knockdown abolished these ameliorative effects of PSPC on apoptosis and P53 acetylation and protein expression in PA-treated L02 cells. Ultimately, PSPC reduced Caspase-3 activation and Bax level, and elevated the Bcl-2 level in HFD-treated mouse livers.

Conclusion

PSPC protected against HFD-induced hepatic apoptosis by promoting Sirt1- dependent inhibition of p53-apoptotic pathway and facilitation of Akt survival pathway. This study indicates that PSPC is a candidate for nutritional intervention of NAFLD.

Hepatic FNDC5 is a potential local protective factor against Non-Alcoholic Fatty Liver

The proteolytic cleavage of Fibronectin type III domain-containing 5 (FNDC5) generates soluble irisin. Initially described as being mainly produced in muscle during physical exercise, irisin mediates adipose tissue thermogenesis and also regulates carbohydrate and lipid metabolism. The aim of this study was to evaluate the hepatic expression of FNDC5 and its role in hepatocytes in Non-Alcoholic Fatty Liver (NAFL). Here we report that hepatic expression of FNDC5 increased with hepatic steatosis and liver injury without impacting the systemic level of irisin in mouse models of NAFLD (HFD and MCDD) and in obese patients. The increased Fndc5 expression in fatty liver resulted from its upregulation in hepatocytes and non-parenchymal cells in mice. The local production of Fndc5 in hepatocytes was influenced by genotoxic stress and p53-dependent pathways. The down-regulation of FNDC5 in human HepG2 cells and in primary mouse hepatocytes increased the expression of PEPCK, a key enzyme involved in gluconeogenesis associated with a decrease in the expression of master genes involved in the VLDL synthesis (CIDEB and APOB). These alterations in FNDC5-silenced cells resulted to increased steatosis and insulin resistance in response to oleic acid and N-acetyl glucosamine, respectively. The downregulation of Fndc5 also sensitized primary hepatocytes to apoptosis in response to TNFα, which has been associated with decreased hepatoprotective autophagic flux. In conclusion, our human and experimental data strongly suggest that the hepatic expression of FNDC5 increased with hepatic steatosis and its upregulation in hepatocytes could dampen the development of NAFLD by negatively regulating steatogenesis and hepatocyte death.

Chinese Herbal Medicine Formula Shenling Baizhu San Ameliorates High-Fat Diet-Induced NAFLD in Rats by Modulating Hepatic MicroRNA Expression Profiles

Objective

The purpose of present study was to investigate the potential mechanism underlying the protective effect of Shenling Baizhu San (SLBZS) on nonalcoholic fatty liver disease (NAFLD) by microRNA (miRNA) sequencing.

Methods

Thirty male Wistar rats were randomly divided into a normal control (NC) group, a high-fat diet (HFD) group, and an SLBZS group. After 12 weeks, the biochemical parameters and liver histologies of the rats were assessed. The Illumina HiSeq 2500 sequencing platform was used to analyse the hepatic miRNA expression profiles. Representative differentially expressed miRNAs were further validated by qRT-PCR. The functions of the differentially expressed miRNAs were analysed by bioinformatics.

Results

Our results identified 102 miRNAs that were differentially expressed in the HFD group compared with the NC group. Among those differentially expressed miRNAs, the expression levels of 28 miRNAs were reversed by SLBZS administration, suggesting the modulation effect of SLBZS on hepatic miRNA expression profiles. The qRT-PCR results confirmed that the expression levels of miR-155-5p, miR-146b-5p, miR-132-3p, and miR-34a-5p were consistent with those detected by sequencing. Bioinformatics analyses indicated that the target genes of the differentially expressed miRNAs reversed by SLBZS were mainly related to metabolic pathways.

Conclusion

This study provides novel insights into the mechanism of SLBZS in protecting against NAFLD; this mechanism may be partly related to the modulation of hepatic miRNA expression and their target pathways.

miRNA Dysregulation in the Development of Non-Alcoholic Fatty Liver Disease and the Related Disorders Type 2 Diabetes Mellitus and Cardiovascular Disease

According to the World Health Organization, the continuing surge in obesity pandemic creates a substantial increase in incidences of metabolic disorders, such as non-alcoholic fatty liver disease (NAFLD), type 2 diabetes mellitus, and cardiovascular disease. MicroRNAs (miRNAs) belong to an evolutionarily conserved class of short (20-22 nucleotides in length) and single-stranded non-coding RNAs. In mammals, miRNAs function as critical post-transcriptional negative regulators involved not only in many biological processes but also in the development of many diseases such as NAFLD and comorbidities. More recently, it has been described that cells can secrete miRNAs in extracellular vesicles, transported by body fluids, and uptaken by other tissues regulating gene expression. Therefore, this could be a mechanism of signaling involved not only in physiological pathways but also in the development of diseases. The association of some miRNA expression profiles with certain disorders has made them very interesting molecules for diagnosis, prognosis, and disease management. The finding of specific miRNA signatures to diagnose NAFLD and related diseases could anticipate the risk of development of related complications and, actually, it is the driving force of present health strategies worldwide. In this review, we have included latest advances in knowledge about the miRNAs involved in the development of NAFLD and related diseases and examined how this knowledge could be used to identify new non-invasive biomarkers and new pharmacological interventions.

Integrated microRNA and proteome analysis reveal a regulatory module in hepatic lipid metabolism disorders in mice with subclinical hypothyroidism

Subclinical hypothyroidism (SCH) is becoming a global health problem due to its increasing prevalence and potential adverse effects, including cardiovascular diseases and nonalcoholic fatty liver disease (NAFLD). However, the association between SCH and NAFLD remains controversial. MicroRNAs (miRNAs/miRs) have been reported to be implicated in lipid metabolism disorders; however, how miRNAs regulate hepatic lipid metabolism in SCH mice remains unknown. The present study investigated miRNA alterations and proteome profiles in an SCH mouse model, which was generated by methimazole administration in mice for 16 weeks. Next, the profiles of 17 miRNAs that are critical to hepatic lipid metabolism and the proteome were investigated using reverse transcription-quantitative polymerase chain reaction and iTRAQ labeling in the liver specimens of SCH (n=9) and control (n=7) mice. Putative target prediction of miRNAs was also conducted using TargetScan and miRanda. Compared with the control mice, SCH mice had 8 miRNAs and 36 proteins with significantly different expression in the liver tissues. Furthermore, a regulatory module containing 3 miRNAs (miR-34a-5p, miR-24-3p and miR-130a-3p) and 4 proteins (thioredoxin, selenium-binding protein 2, elongation factor 1β and prosaposin) was identified. Overall, integrated analysis of miRNAs and the proteome highlighted a regulatory module between miRNAs and proteins, which, to a certain extent, may contribute to a better understanding of hepatic lipid metabolism disorders in SCH mice.

Hepatic microRNA Expression by PGC-1α and PGC-1β in the Mouse

The fine-tuning of liver metabolism is essential to maintain the whole-body homeostasis and to prevent the onset of diseases. The peroxisome proliferator-activated receptor-γ coactivators (PGC-1s) are transcriptional key players of liver metabolism, able to regulate mitochondrial function, gluconeogenesis and lipid metabolism. Their activity is accurately modulated by post-translational modifications. Here, we showed that specific PGC-1s expression can lead to the upregulation of different microRNAs widely implicated in liver physiology and diseases development and progression, thus offering a new layer of complexity in the control of hepatic metabolism.

The Crosstalk of miRNA and Oxidative Stress in the Liver: From Physiology to Pathology and Clinical Implications

The liver is the central metabolic organ of mammals. In humans, most diseases of the liver are primarily caused by an unhealthy lifestyle-high fat diet, drug and alcohol consumption- or due to infections and exposure to toxic substances like aflatoxin or other environmental factors. All these noxae cause changes in the metabolism of functional cells in the liver. In this literature review we focus on the changes at the miRNA level, the formation and impact of reactive oxygen species and the crosstalk between those factors. Both, miRNAs and oxidative stress are involved in the multifactorial development and progression of acute and chronic liver diseases, as well as in viral hepatitis and carcinogenesis, by influencing numerous signaling and metabolic pathways. Furthermore, expression patterns of miRNAs and antioxidants can be used for biomonitoring the course of disease and show potential to serve as possible therapeutic targets.

Melatonin Effects on Non-Alcoholic Fatty Liver Disease Are Related to MicroRNA-34a-5p/Sirt1 Axis and Autophagy

Melatonin, an indole produced by pineal and extrapineal tissues, but also taken with a vegetarian diet, has strong anti-oxidant, anti-inflammatory and anti-obesogenic potentials. Non-alcoholic fatty liver disease (NAFLD) is the hepatic side of the metabolic syndrome. NAFLD is a still reversible phase but may evolve into steatohepatitis (NASH), cirrhosis and carcinoma. Currently, an effective therapy for blocking NAFLD staging is lacking. Silent information regulator 1 (SIRT1), a NAD+ dependent histone deacetylase, modulates the energetic metabolism in the liver. Micro-RNA-34a-5p, a direct inhibitor of SIRT1, is an emerging indicator of NAFLD grading. Thus, here we analyzed the effects of oral melatonin against NAFLD and underlying molecular mechanisms, focusing on steatosis, ER stress, mitochondrial shape and autophagy. Male C57BL/6J (WT) and SIRT1 heterozygous (HET) mice were placed either on a high-fat diet (58.4% energy from lard) (HFD) or on a standard maintenance diet (8.4% energy from lipids) for 16 weeks, drinking melatonin (10 mg/kg) or not. Indirect calorimetry, glucose tolerance, steatosis, inflammation, ER stress, mitochondrial changes, autophagy and microRNA-34a-5p expression were estimated. Melatonin improved hepatic metabolism and steatosis, influenced ER stress and mitochondrial shape, and promoted autophagy in WT HFD mice. Conversely, melatonin was ineffective in HET HFD mice, maintaining NASH changes. Indeed, autophagy was inconsistent in HET HFD or starved mice, as indicated by LC3II/LC3I ratio, p62/SQSTM1 and autophagosomes estimation. The beneficial role of melatonin in dietary induced NAFLD/NASH in mice was related to reduced expression of microRNA-34a-5p and sterol regulatory element-binding protein (SREBP1) but only in the presence of full SIRT1 availability.

Gender effect of hyperuricemia on the development of nonalcoholic fatty liver disease (NAFLD): A clinical analysis and mechanistic study

BACKGROUND AND AIMS

Hyperuricemia is a risk factor for nonalcoholic fatty liver disease (NAFLD), however, the effect of gender on the hyperuricemia-related NAFLD development remains unclear. Here, we evaluated the clinical characteristics of NAFLD patients with hyperuricemia, and experimentally recapitulated this condition in male rats in order to gain insights on the possible impact of gender on the development of NAFLD in patients with hyperuricemia.

METHODS

The clinical characteristics of 238 NAFLD patients, together with the impacts of hyperuricemia on the major parameters related to the development of NALFD were analysed. In animal studies, NAFLD with hyperuricemia was induced in male SD rats using high-yeast high-fat diet containing potassium oxonate. The impact of uric acids on liver pathology, and the expression patterns of key molecules involved in the development of NAFLD, including silent information regulator 1 (SIRT1), nuclear factor kappa B subunit p65 (NF-κB p65), fork-head box class O-3a (FOXO3a), androgen receptor (AR), and xanthine oxidase (XO) were analysed.

RESULTS

Male NAFLD patients with hyperuricemia displayed more frequent and extensive liver injury than those in female patients. In male rats, hyperuricemia was associated with increased levels of insulin, alanine aminotransferase (ALT) and triglyceride (TG). At the molecular level, hyperuricemia was associated with decreased expression of SIRT1 and its phosphorylation, phosphorylation of FOXO3a, increased expression of AR and XO, and deacetylation of NF-κB P65.

CONCLUSIONS

Hyperuricemia is a compounding factor for NAFLD, particularly in males. The severer hepatic injury observed in male NAFLD patients may be attributed to the suppression of SIRT1 signalling induced by hyperuricemia.

Hallmarks of Aging in the Liver

While the liver demonstrates remarkable resilience during aging, there is growing evidence that it undergoes all the cellular hallmarks of aging, which increases the risk of liver and systemic disease. The aging process in the liver is driven by alterations of the genome and epigenome that contribute to dysregulation of mitochondrial function and nutrient sensing pathways, leading to cellular senescence and low-grade inflammation. These changes promote multiple phenotypic changes in all liver cells (hepatocytes, liver sinusoidal endothelial, hepatic stellate and Küpffer cells) and impairment of hepatic function. In particular, age-related changes in the liver sinusoidal endothelial cells are a significant but under-recognized risk factor for the development of age-related cardiometabolic disease.

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Liver aging is driven by transcription and metabolic epigenome alterations.

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This leads to cellular senescence and low-grade inflammation.

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Hepatocyte, sinusoidal endothelial, stellate and Küpffer cells undergoes the hallmarks of aging.

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Each cell type demonstrates phenotypical cellular changes with age.

MicroRNA-30b regulates insulin sensitivity by targeting SERCA2b in non-alcoholic fatty liver disease

BACKGROUND & AIMS

Insulin resistance is strongly associated with non-alcoholic fatty liver disease, a chronic, obesity-related liver disease. Increased endoplasmic reticulum (ER) stress plays an important role in the development of insulin resistance. In this study, we investigated the roles of miRNAs in regulating ER stress in the liver of rats with obesity.

METHODS

We used miRNA microarray to determine the miRNA expression profiles in the liver of rats fed with a high fat diet (HFD). We used prediction algorithms and luciferase reporter assay to identify the target gene of miRNAs. To overexpress the miRNA miR-30b or inhibit miR-30b rats were injected with lentivirus particles containing PGLV3-miR-30b or PGLV3-miR-30b antimiR through tail vein. Hepatic steatosis was measured using transient elastography in human subjects.

RESULTS

Our data showed that miR-30b was markedly up-regulated in the liver of HFD-treated rats. Bioinformatic and in vitro and in vivo studies led us to identify sarco(endo)plasmic reticulum Ca²⁺ -ATPase 2b (SERCA2b), as a novel target of miR-30b. Overexpression of miR-30b induced ER stress and insulin resistance in rats fed with normal diet, whereas inhibition of miR-30b by miR-30b antimiR suppressed ER stress and insulin resistance in HFD-treated rats. Finally, our data demonstrated that there was a positive correlation between serum miR-30b levels and hepatic steatosis or homoeostasis model assessment of insulin resistance (HOMA-IR) in human subjects.

CONCLUSIONS

Our findings suggest that miR-30b represents not only a potential target for the treatment of insulin resistance, but also a non-invasive disease biomarker of NAFLD.

Adiponectin is required for pioglitazone-induced improvements in hepatic steatosis in mice fed a high-fat diet

Pioglitazone has been used for the treatment of nonalcoholic fatty liver disease (NAFLD) related to diabetes. The role of adiponectin in pioglitazone-induced improvements in NAFLD was studied by using wild-type (adipoWT) and adiponectin knockout (adipoKO) mice. High-fat diet fed mice were insulin resistant, glucose intolerant and had increased hepatic lipid accumulation as evidenced by increased NAFLD activity score. Despite pioglitazone has improved insulin resistance in both genotypes, hepatic steatosis was only improved in adipoWT obese mice. Amelioration of NAFLD in adipoWT mice promoted by pioglitazone was associated with up-regulation of Pparg, Fgf21 and down-regulation of Pepck liver expression. On the other hand, resistance to pioglitazone treatment in adipoKO mice was associated with increased expression of miR-192 and Hsl, which was not followed by increased fatty acid oxidation. In conclusion, our data provides evidence that increased adiponectin production by pioglitazone is necessary for its beneficial action on NAFLD.

Can Epigenetics of Endothelial Dysfunction Represent the Key to Precision Medicine in Type 2 Diabetes Mellitus?

In both developing and industrialized Countries, the growing prevalence of Type 2 Diabetes Mellitus (T2DM) and the severity of its related complications make T2DM one of the most challenging metabolic diseases worldwide. The close relationship between genetic and environmental factors suggests that eating habits and unhealthy lifestyles may significantly affect metabolic pathways, resulting in dynamic modifications of chromatin-associated proteins and homeostatic transcriptional responses involved in the progression of T2DM. Epigenetic mechanisms may be implicated in the complex processes linking environmental factors to genetic predisposition to metabolic disturbances, leading to obesity and type 2 diabetes mellitus (T2DM). Endothelial dysfunction represents an earlier marker and an important player in the development of this disease. Dysregulation of the endothelial ability to produce and release vasoactive mediators is recognized as the initial feature of impaired vascular activity under obesity and other insulin resistance conditions and undoubtedly concurs to the accelerated progression of atherosclerotic lesions and overall cardiovascular risk in T2DM patients. This review aims to summarize the most current knowledge regarding the involvement of epigenetic changes associated with endothelial dysfunction in T2DM, in order to identify potential targets that might contribute to pursuing “precision medicine” in the context of diabetic illness.

miR-122 promotes hepatic lipogenesis via inhibiting the LKB1/AMPK pathway by targeting Sirt1 in non-alcoholic fatty liver disease

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is a common hepatic disease with an increasing prevalence but an unclear aetiology. This study aimed to investigate the functional implications of microRNA-122 (miR-122) in the pathogenesis of NAFLD and the possible molecular mechanisms.

METHODS

Both in vitro and in vivo models of NAFLD were generated by treating HepG2 and Huh-7 cells with free fatty acids (FFA) and by feeding mice a high-fat diet (HFD), respectively. HE and Oil Red O staining were used to examine liver tissue morphology and lipid deposition, respectively. Immunohistochemical (IHC) staining was used to examine Sirt1 expression in liver tissues. qRT-PCR and Western blotting were employed to measure the expression of miR-122, Sirt1, and proteins involved in lipogenesis and the AMPK pathway. Enzyme-linked immunosorbent assay (ELISA) was used to quantify triglyceride (TG) levels in HepG2 and Huh-7 cells and in liver tissues. The interaction between miR-122 and the Sirt1 gene was further examined by a dual luciferase reporter assay and RNA-immunoprecipitation (RIP).

RESULTS

NAFLD hepatic tissues and FFA-treated HepG2 and Huh-7 cells presented excess lipid production and TG secretion, accompanied by miR-122 upregulation, Sirt1 downregulation, and potentiated lipogenesis-related genes. miR-122 suppressed Sirt1 expression via binding to its 3'-untranslated region (UTR). Knockdown of miR-122 effectively mitigated excessive lipid production and suppressed the expression of lipogenic genes in FFA-treated HepG2 and Huh-7 cells via upregulating Sirt1. Furthermore, miR-122 knockdown activated the LKB1/AMPK signalling pathway.

CONCLUSION

The inhibition of miR-122 protects hepatocytes from lipid metabolic disorders such as NAFLD and suppresses lipogenesis via elevating Sirt1 and activating the AMPK pathway. These data support miR-122 as a promising biomarker and drug target for NAFLD.

Telomere Dysfunction Induces Sirtuin Repression that Drives Telomere-Dependent Disease

Telomere shortening is associated with stem cell decline, fibrotic disorders, and premature aging through mechanisms that are incompletely understood. Here, we show that telomere shortening in livers of telomerase knockout mice leads to a p53-dependent repression of all seven sirtuins. P53 regulates non-mitochondrial sirtuins (Sirt1, 2, 6, and 7) post-transcriptionally through microRNAs (miR-34a, 26a, and 145), while the mitochondrial sirtuins (Sirt3, 4, and 5) are regulated in a peroxisome proliferator-activated receptor gamma co-activator 1 alpha-/beta-dependent manner at the transcriptional level. Administration of the NAD(+) precursor nicotinamide mononucleotide maintains telomere length, dampens the DNA damage response and p53, improves mitochondrial function, and, functionally, rescues liver fibrosis in a partially Sirt1-dependent manner. These studies establish sirtuins as downstream targets of dysfunctional telomeres and suggest that increasing Sirt1 activity alone or in combination with other sirtuins stabilizes telomeres and mitigates telomere-dependent disorders.

The role of different SIRT1-mediated signaling pathways in toxic injury

Common environmental pollutants and drugs encountered in everyday life can cause toxic damage to the body through oxidative stress, inflammatory stimulation, induction of apoptosis, and inhibition of energy metabolism. Silent information regulator 1 (SIRT1), a nicotinamide adenine dinucleotide-dependent deacetylase, is a member of the evolutionarily highly conserved Sir2 (silent information regulator 2) superprotein family, which is located in the nucleus and cytoplasm. It can deacetylate protein substrates in various signal transduction pathways to regulate gene expression, cell apoptosis and senescence, participate in the process of neuroprotection, energy metabolism, inflammation and the oxidative stress response in living organisms, and plays an important role in toxic damage caused by toxicants and in the process of SIRT1 activator/inhibitor antagonized toxic damage. This review summarizes the role that SIRT1 plays in toxic damage caused by toxicants via its interactions with protein substrates in certain signaling pathways.

Effect of resveratrol on non-alcoholic fatty liver disease

The aim of the present study was to investigate the effect of a micronized formulation of trans-resveratrol in humans with non-alcoholic fatty liver disease (NAFLD). Trans-Resveratrol has been used in the form of micronized formulation, which is better absorbed, has strong antioxidants effects, is more effective than plain resveratrol formulations and is circulated on the market as a food supplement. Resveratrol (3,5,4′-trihydroxy-trans-stilbene) is a stilbenoid and a phytoalexin produced by several plants. NAFLD is an increasing clinical problem involving the liver for which effective treatments are required. The present study was based on two patient groups. The study, which commenced on April 2013 and finished on April 2015, included 44 patients, aged 29–70 years, with an average weight of 84.6 kg (n=22 per group; 28 men and 16 women) who were randomly assigned to groups and given 50 mg Evelor capsule (n=22) and 200 mg Evelor H tablet (n=22) correspondingly on a daily basis. The patients were followed up for 6 months. Quantity fat measurements, with ultrasound on the liver and kidney, were carried out. There was an initial measurement (time 1) and one after six months (time 2). The study results showed the effects of Trans-resveratrol micronized formulation in reducing the liver fat, as well as decreasing hepatic enzymes, serum glutamate pyruvic transaminase (SGPT) and gamma-glutamyl transpeptidase (g-GT) and insulin resistance. At the end of the study, the statistical analysis showed a statistically significant reduction on the liver fat. These data demonstrate that use of Trans-resveratrol micronized formulation improves features of NAFLD, and prevents liver damage. Thus, Trans-resveratrol micronized formulation can be a new treatment method for NAFLD.

microRNA-34a aggravates coxsackievirus B3-induced apoptosis of cardiomyocytes through the SIRT1-p53 pathway

Viral myocarditis is inflammation of the myocardium mainly caused by a viral infection, and coxsackievirus B3 (CVB3) infection is one of the most common. It is well known that cardiomyocyte apoptosis is involved in the pathogenesis of viral myocarditis. microRNAs (miRNAs, miRs) are endogenous noncoding oligoribonucleotides involved in various pathological conditions, and miR-34a is one of the miRNAs causing apoptosis. Whether miR-34a participates in cardiomyocyte apoptosis during CVB3 infection and the underlying mechanisms is still unclear. In this in vitro study, we found that miR-34a expression increased in cardiomyocytes after CVB3 infection. Furthermore, we found that CVB3 infection augmented histone deacetylase 1 (HDAC1) and Bax expression while inhibiting sirtuin 1 (SIRT1) and Bcl-2 expression, along with the acetylated p53 (Ac-p53) upregulation in cardiomyocytes. The above-mentioned phenomenon was reversed by a miR-34a inhibitor after CVB3 infection. In addition, the Ac-p53 amount increased in CVB3-infected cardiomyocytes, and SRT1720 and trichostatin A (TSA) pretreatment decreased Ac-p53 levels. After pifithrin-α pretreatment of CVB3-infected cardiomyocytes, the protein expression level of HDAC1 decreased while that of SIRT1 increased. Moreover, miR-34a expression and CVB3-induced apoptosis of cardiomyocytes were attenuated by pretreatment with SRT1720, TSA, or pifithrin-α, accompanied with Bax downregulation and Bcl-2 upregulation. In summary, these data indicate that miR-34a induces cardiomyocyte apoptosis by downregulating SIRT1, and the activation of the SIRT1-p53 pathway contributes to CVB3-induced apoptosis of cardiomyocytes. Thus, miR-34a might serve as a potential therapeutic target because it promotes cardiomyocyte apoptosis through the SIRT1-p53 signaling pathway.

Tauroursodeoxycholic acid (TUDCA) abolishes chronic high salt-induced renal injury and inflammation

AIM

Chronic high salt intake exaggerates renal injury and inflammation, especially with the loss of functional ET_B receptors. Tauroursodeoxycholic acid (TUDCA) is a chemical chaperone and bile salt that is approved for the treatment of hepatic diseases. Our aim was to determine whether TUDCA is reno-protective in a model of ET_B receptor deficiency with chronic high salt-induced renal injury and inflammation.

METHODS

ET_B -deficient and transgenic control rats were placed on normal (0.8% NaCl) or high salt (8% NaCl) diet for 3 weeks, receiving TUDCA (400 mg/kg/d; ip) or vehicle. Histological and biochemical markers of kidney injury, renal cell death and renal inflammation were assessed.

RESULTS

In ET_B -deficient rats, high salt diet significantly increased glomerular and proximal tubular histological injury, proteinuria, albuminuria, excretion of tubular injury markers KIM-1 and NGAL, renal cortical cell death and renal CD4⁺ T cell numbers. TUDCA treatment increased proximal tubule megalin expression as well as prevented high salt diet-induced glomerular and tubular damage in ET_B -deficient rats, as indicated by reduced kidney injury markers, decreased glomerular permeability and proximal tubule brush border restoration, as well as reduced renal inflammation. However, TUDCA had no significant effect on blood pressure.

CONCLUSIONS

TUDCA protects against the development of glomerular and proximal tubular damage, decreases renal cell death and inflammation in the renal cortex in rats with ET_B receptor dysfunction on a chronic high salt diet. These results highlight the potential use of TUDCA as a preventive tool against chronic high salt induced renal damage.

Measuring the Impact of Bile Acids on the Membrane Order of Primary Hepatocytes and Isolated Mitochondria by Fluorescence Imaging and Spectroscopy

Cholestasis is characterized by impaired secretion of bile flow that can result in the accumulation of highly abnormal levels of bile acids causing hepatocyte and biliary injury. As amphipathic molecules, bile acids can intercalate in lipid membranes, and pathophysiologic concentrations of bile acids have the potential to induce marked changes in the biophysical properties of biomembranes, including membrane ordering. These effects, particularly on the mitochondrial and plasma membranes, have been proposed to trigger toxicity of bile acids. This chapter details different fluorescence-based methods (fluorescence polarization, and spectroscopy/imaging of solvatochromic dyes) to evaluate the impact of different bile acids on membrane order. Protocols are described for the application of these methods to biomimetic vesicles, isolated mitochondria, and hepatocytes, following a bottom-up approach.

Glucagon-Induced Acetylation of Energy-Sensing Factors in Control of Hepatic Metabolism

The liver is the central organ of glycolipid metabolism, which regulates the metabolism of lipids and glucose to maintain energy homeostasis upon alterations of physiological conditions. Researchers formerly focused on the phosphorylation of glucagon in controlling liver metabolism. Noteworthily, emerging evidence has shown glucagon could additionally induce acetylation to control hepatic metabolism in response to different physiological states. Through inducing acetylation of complex metabolic networks, glucagon interacts extensively with various energy-sensing factors in shifting from glucose metabolism to lipid metabolism during prolonged fasting. In addition, glucagon-induced acetylation of different energy-sensing factors is involved in the advancement of nonalcoholic fatty liver disease (NAFLD) to liver cancer. Here, we summarize the latest findings on glucagon to control hepatic metabolism by inducing acetylation of energy-sensing factors. Finally, we summarize and discuss the potential impact of glucagon on the treatment of liver diseases.

P53/NRF2 mediates SIRT1's protective effect on diabetic nephropathy

Diabetic nephropathy (DN) is the leading cause of end stage renal disease, posing a severe threat to public health. Previous studies reported the protective role of sirtuin 1 (SIRT1) in DN, encouraging the investigation of more potent and specific SIRT1 activators. SRT2104 is a novel, first-in-class, highly selective small-molecule activator of SIRT1, with its effect and mechanism unknown on DN. To this end, streptozotocin-induced C57BL/6 wild-type (WT) diabetic mice were treated with SRT2104, for 24 weeks. To determine whether SRT2104 acted through inhibition of P53 - a substrate of SIRT1, the P53 activator nutlin3a was administered to the WT diabetic mice in the presence of SRT2104. In order to test whether nuclear factor erythroid 2-related factor 2 (NRF2) - the master of cellular antioxidants - mediated SIRT1 and P53's actions, WT and Nrf2 gene knockout (KO) diabetic mice were treated with SRT2104 or the P53 inhibitor pifithrin-α (PFT-α). In the WT mice, SRT2104 enhanced renal SIRT1 expression and activity, deacetylated P53, and activated NRF2 antioxidant signaling, providing remarkable protection against the DM-induced renal oxidative stress, inflammation, fibrosis, glomerular remodeling and albuminuria. These effects were completely abolished in the presence of nutlin3a. Deletion of the Nrf2 gene completely abrogated the efficacies of SRT2104 and PFT-α in elevating antioxidants and ameliorating DN, despite their abilities to activate SIRT1 and inhibit P53 in the Nrf2 KO mice. The present study reports the beneficial effects of SRT2104 on DN, uncovering a SIRT1/P53/NRF2 pathway that modulates the pathogenesis of DN.

Comprehensive bioinformatics analysis of critical lncRNAs, mRNAs and miRNAs in non‑alcoholic fatty liver disease

Non‑alcoholic fatty liver disease (NAFLD) is the most common fatty liver disease in developed countries, in which fat accumulation in the liver is induced by non‑alcoholic factors. The present study was conducted to identify NAFLD‑associated long non‑coding RNAs (lncRNAs), mRNAs and microRNAs (miRNAs). The microarray dataset GSE72756, which included 5 NAFLD liver tissues and 5 controls, was acquired from the Gene Expression Omnibus database. Differentially expressed lncRNAs (DE‑lncRNAs) and mRNAs (DE‑mRNAs) were detected using the pheatmap package. Using the clusterProfiler package and Cytoscape software, enrichment and protein‑protein interaction (PPI) network analyses were conducted to evaluate the DE‑mRNAs. Next, the miRNA‑lncRNA‑mRNA interaction network was visualized using Cytoscape software. Additionally, RP11‑279F6.1 and AC004540.4 expression levels were analyzed by reverse transcription quantitative polymerase chain reaction. There were 318 DE‑lncRNAs and 609 DE‑mRNAs identified in the NAFLD tissues compared with the normal tissues. Jun proto‑oncogene, AP‑1 transcription factor subunit (JUN), which is regulated by AC004540.4 and RP11‑279F6.1, exhibited higher degree compared with other nodes in the PPI network. Furthermore, miR‑409‑3p and miR‑139 (targeting JUN) were predicted as PPI network nodes. In the miRNA‑lncRNA‑mRNA network, miR‑20a and B‑cell lymphoma 2‑like 11 (BCL2L11) were among the top 10 nodes. Additionally, BCL2L11, AC004540.4 and RP11‑279F6.1 were targeted by miR‑20a, miR‑409‑3p and miR‑139 in the miRNA‑lncRNA‑mRNA network, respectively. RP11‑279F6.1 and AC004540.4 expression was markedly enhanced in NAFLD liver tissues. These key RNAs may be involved in the pathogenic mechanisms of NAFLD.

Modulation of miR-34a/SIRT1 signaling protects cochlear hair cells against oxidative stress and delays age-related hearing loss through coordinated regulation of mitophagy and mitochondrial biogenesis

Mitophagy and mitochondrial biogenesis are 2 pathways that regulate mitochondrial content and metabolism maintaining cellular homeostasis. The imbalance between these opposing processes impairs mitochondrial function and is suggested to be the pathophysiological basis of a variety of neurodegenerative diseases and aging. Here we investigated the role of mitophagy and mitochondrial biogenesis in oxidative damage to the cochlear hair cells and age-related hearing loss. In cultured mouse House Ear Institute-Organ of Corti 1 hair cells, oxidative stress activated mitophagy but inhibited mitochondrial biogenesis and impaired mitochondrial function. Pharmacological inhibition of miR-34a/SIRT1 signaling enhanced mitophagy, mitochondrial biogenesis, and attenuated House Ear Institute-Organ of Corti 1 cell death induced by oxidative stress. In the cochlea of C57BL/6 mice, mitophagy and mitochondrial biogenesis were both upregulated during aging. Long-term supplementation with resveratrol, a SIRT1 activator, not only improved the balance between mitophagy and mitochondrial biogenesis but also significantly reduced age-related cochlear hair cell loss, spiral ganglion neuron loss, stria vascularis atrophy, and hearing threshold shifts in C57BL/6 mice. Moreover, SIRT1 overexpression or miR-34a deficiency both attenuated age-related cochlear hair cell loss and hearing loss in C57BL/6 mice. Our findings reveal that imbalance between mitophagy and mitochondrial biogenesis contributes to cochlea hair cell damage caused by oxidative stress and during aging. Coordinated regulation of these 2 processes by miR-34a/SIRT1 signaling might serve as a promising approach for the treatment of age-related cochlear degeneration and hearing loss.

Regulatory Non-coding RNAs Network in Non-alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) spectrum comprises simple steatosis and non-alcoholic steatohepatitis (NASH) that can lead to fibrosis and cirrhosis. The patients usually have no history of excessive alcohol consumption and other etiologies that can cause fatty liver. Understanding of the pathophysiology of NAFLD has revealed that non-coding RNAs (ncRNAs) play significant roles in modulating the disease susceptibility, pathogenesis and progression. Currently, the ncRNAs are grouped according to their sizes and their regulatory or housekeeping functions. Each of these ncRNAs has a wide range of involvement in the regulation of the genes and biological pathways. Here, we briefly review the current literature the regulatory ncRNAs in NAFLD pathogenesis and progression, mainly the microRNAs, long non-coding RNAs and circular RNAs. We also discuss the co-regulatory functions and interactions between these ncRNAs in modulating the disease pathogenesis. Elucidation of ncRNAs in NAFLD may facilitate the identification of early diagnostic biomarkers and development of therapeutic strategies for NAFLD.

Celastrol Protects From Cholestatic Liver Injury Through Modulation of SIRT1-FXR Signaling

Celastrol, derived from the roots of the Tripterygium Wilfordi, shows a striking effect on obesity. In the present study, the role of celastrol in cholestasis was investigated using metabolomics and transcriptomics. Celastrol treatment significantly alleviated cholestatic liver injury in mice induced by α-naphthyl isothiocyanate (ANIT) and thioacetamide (TAA). Celastrol was found to activate sirtuin 1 (SIRT1), increase farnesoid X receptor (FXR) signaling and inhibit nuclear factor-kappa B and P53 signaling. The protective role of celastrol in cholestatic liver injury was diminished in mice on co-administration of SIRT1 inhibitors. Further, the effects of celastrol on cholestatic liver injury were dramatically decreased in Fxr-null mice, suggesting that the SIRT1-FXR signaling pathway mediates the protective effects of celastrol. These observations demonstrated a novel role for celastrol in protecting against cholestatic liver injury through modulation of the SIRT1 and FXR.

Role of Noncoding RNA in Development of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is increasing in prevalence globally, but little is known about its specific molecular mechanisms. During the past decade, noncoding RNAs (ncRNAs) have been linked to NAFLD initiation and progression. They are a class of RNAs that play an important role in regulating gene expression despite not encoding proteins. This review summarizes recent research on the relationship between ncRNAs and NAFLD. We discussed the potential applicability of ncRNAs as a biomarker for early NAFLD diagnosis and assessment of disease severity. With further study, ncRNAs should prove to be valuable new targets for NAFLD treatment and benefit the development of noninvasive diagnostic methods.

Inhibition of P53/miR-34a improves diabetic endothelial dysfunction via activation of SIRT1

Endothelial dysfunction contributes to diabetic macrovascular complications, resulting in high mortality. Recent findings demonstrate a pathogenic role of P53 in endothelial dysfunction, encouraging the investigation of the effect of P53 inhibition on diabetic endothelial dysfunction. Thus, high glucose (HG)‐treated endothelial cells (ECs) were subjected to pifithrin‐α (PFT‐α)—a specific inhibitor of P53, or P53‐small interfering RNA (siRNA), both of which attenuated the HG‐induced endothelial inflammation and oxidative stress. Moreover, inhibition of P53 by PFT‐α or P53‐siRNA prohibited P53 acetylation, decreased microRNA‐34a (miR‐34a) level, leading to a dramatic increase in sirtuin 1 (SIRT1) protein level. Interestingly, the miR‐34a inhibitor (miR‐34a‐I) and PFT‐α increased SIRT1 protein level and alleviated the HG‐induced endothelial inflammation and oxidative stress to a similar extent; however, these effects of PFT‐α were completely abrogated by the miR‐34a mimic. In addition, SIRT1 inhibition by EX‐527 or Sirt1‐siRNA completely abolished miR‐34a‐I's protection against HG‐induced endothelial inflammation and oxidative stress. Furthermore, in the aortas of streptozotocin‐induced diabetic mice, both PFT‐α and miR‐34a‐I rescued the inflammation, oxidative stress and endothelial dysfunction caused by hyperglycaemia. Hence, the present study has uncovered a P53/miR‐34a/SIRT1 pathway that leads to endothelial dysfunction, suggesting that P53/miR‐34a inhibition could be a viable strategy in the management of diabetic macrovascular diseases.

Fine-Tuning of Sirtuin 1 Expression Is Essential to Protect the Liver From Cholestatic Liver Disease

Cholestasis comprises aetiologically heterogeneous conditions characterized by accumulation of bile acids in the liver that actively contribute to liver damage. Sirtuin 1 (SIRT1) regulates liver regeneration and bile acid metabolism by modulating farnesoid X receptor (FXR); we here investigate its role in cholestatic liver disease. We determined SIRT1 expression in livers from patients with cholestatic disease, in two experimental models of cholestasis, as well as in human and murine liver cells in response to bile acid loading. SIRT1-overexpressing (SIRT^oe ) and hepatocyte-specific SIRT1-KO (knockout) mice (SIRT^hep-/- ) were subjected to bile duct ligation (BDL) and were fed with a 0.1% DDC (3,5-diethoxycarbonyl-1,4-dihydrocollidine) diet to determine the biological relevance of SIRT1 during cholestasis. The effect of NorUDCA (24-norursodeoxycholic acid) was tested in BDL/SIRT^oe mice. We found that SIRT1 was highly expressed in livers from cholestatic patients, mice after BDL, and Mdr2 knockout mice (Mdr2^-/- ) animals. The detrimental effects of SIRT1 during cholestasis were validated in vivo and in vitro. SIRT^oe mice showed exacerbated parenchymal injury whereas SIRT^hep-/- mice evidenced a moderate improvement after BDL and 0.1% DDC feeding. Likewise, hepatocytes isolated from SIRT^oe mice showed increased apoptosis in response to bile acids, whereas a significant reduction was observed in SIRT^hep-/- hepatocytes. Importantly, the decrease, but not complete inhibition, of SIRT1 exerted by norUDCA treatment correlated with pronounced improvement in liver parenchyma in BDL/SIRT^oe mice. Interestingly, both SIRT1 overexpression and hepatocyte-specific SIRT1 depletion correlated with inhibition of FXR, whereas modulation of SIRT1 by NorUDCA associated with restored FXR signaling. Conclusion: SIRT1 expression is increased during human and murine cholestasis. Fine-tuning expression of SIRT1 is essential to protect the liver from cholestatic liver damage.

The Circulating Micro-RNAs (-122, -34a and -99a) as Predictive Biomarkers for Non-Alcoholic Fatty Liver Diseases

BACKGROUND

It remains essential for patient safety to develop non-invasive diagnostic tools to diagnose non-alcoholic fatty liver rather than invasive techniques.

AIM

Our case-control study was to address the value of circulating miRNAs as a potential non-invasive biomarker for the diagnosis of non-alcoholic fatty acid diseases (NAFLD) and monitoring of disease progression.

METHODS

Routine clinical assessment, laboratory tests, anthropometric study, and liver biopsy results reported for 210 patients with NAFLD (124 patients of simple steatosis (SS) and 86 of non-alcoholic steatohepatitis (NASH)). Apparently matched for age and gender, healthy participants (n= 90) were enrolled as a control group. Serum samples were tested for micro-RNAs (-122, -34a and -99a) by quantitative-PCR.

RESULTS

By histopathology, 124 of the NAFLD group were of SS and 86 patients were of NASH. Compared with the control subjects, both mi-RNA-122 and -34a levels were increased in NAFLD (p< 001) and at a cut-off = 1.261, mi-RNA-122 had 92% sensitivity, 85% specificity to differentiate NAFLD from healthy controls, while mi-RNA-99a were significantly decreased in NAFLD patients with an observed decrease in disease severity, and at a cut-off = 0.46, miRNA-99a had 94% sensitivity and 96% specificity to discriminate SS from NASH.

CONCLUSION

The integration of a circulating mi-RNA panel to diagnose NAFLD cases and to discriminate between SS and NASH. Large-scale study is still needed to verify the other mi-RNA profiles and their role in NAFLD pathogenesis and targeting therapy.

Induction of hepatic miR-34a by perfluorooctanoic acid regulates metabolism-related genes in mice

Perfluorooctanoic acid (PFOA) is a widespread organic pollutant with various toxicological impacts on the liver. Members of the miR-34 family are P53-targeted growth suppressors. We found that PFOA exposure (5 mg/kg/d PFOA for 28 d) resulted in a significant increase of miR-34a in the livers of mice but had no effect on either miR-34b or miR-34c. We knocked out miR-34a in mice to explore the role of elevated miR-34a in PFOA-induced liver toxicity. Compared with the corresponding untreated control, significant increases in liver weight as well as serum alanine transaminase, aspartate aminotransferase, and cholinesterase levels were observed in miR-34a^-/- and wild-type mice after PFOA exposure. Hepatic cells showed similar swelling in both miR-34a^-/- and wild-type mice after PFOA treatment. Hepatic RNA-sequencing (RNA-seq) showed that PFOA led to significant alteration in lipid metabolism genes, especially those involved in the peroxisome proliferator-activated receptor pathway, in both wild-type and miR-34a null mice. With or without PFOA treatment, relatively fewer genes were altered in miR-34a^-/- livers compared to wild-type livers. Among the changed genes by miR-34a, the most dominant were metabolism-related genes, such as Fabp3, Cyp7a1, and Apoa4. Our in vivo study indicated that miR-34a mainly exerts a metabolic regulation role, rather than the pro-apoptosis and cell cycle arrest role reported previously by many in vitro studies. In addition, although hepatic P53 was unchanged, the active type of P53 (acetylated P53 (acetyl-p53, Lys379)) was markedly altered under PFOA treatment. Therefore, the increase in acetylated P53 may have activated the transcription of miR-34a in mouse livers after PFOA treatment.

miRNA Signature in NAFLD: A Turning Point for a Non-Invasive Diagnosis

Nonalcoholic fatty liver disease (NAFLD) defines a wide pathological spectrum ranging from simple steatosis to nonalcoholic steatohepatitis (NASH) which may predispose to liver cirrhosis and hepatocellular carcinoma. It represents the leading cause of hepatic damage worldwide. Diagnosis of NASH still requires liver biopsy but due to the high prevalence of NAFLD, this procedure, which is invasive, is not practicable for mass screening. Thus, it is crucial to non-invasively identify NAFLD patients at higher risk of progression to NASH and fibrosis. It has been demonstrated that hepatic fat content and progressive liver damage have a strong heritable component. Therefore, genetic variants associated with NAFLD have been proposed as non-invasive markers to be used in clinical practice. However, genetic variability is not completely explained by these common variants and it is possible that many of the phenotypic differences result from gene-environment interactions. Indeed, NAFLD development and progression is also modulated by epigenetic factors, in particular microRNAs (miRNAs), which control at post-transcriptional level many complementary target mRNAs and whose dysregulation has been shown to have high prognostic and predictive value in NAFLD. The premise of the current review is to discuss the role of miRNAs as pathogenic factors, risk predictors and therapeutic targets in NAFLD.

Amelioration of hepatic steatosis is associated with modulation of gut microbiota and suppression of hepatic miR-34a in Gynostemma pentaphylla (Thunb.) Makino treated mice

Background

Non-alcoholic fatty liver disease (NAFLD) is a chronic and progressive liver disease with an increased risk of morbidity and mortality. However, so far no specific pharmacotherapy has been approved. Gynostemma pentaphylla (Thunb.) Makino (GP) is a traditional Chinese medicine that is widely used against hyperlipemia as well as hyperglycemia. This study aims to evaluate the effect of GP on NAFLD and explore the possible mechanism.

Methods

High-fat-diet induced NAFLD mice model were orally administrated with GP at dose of 11.7 g/kg or equivalent volume of distilled water once a day for 16 weeks. Body weight, food intake and energy expenditure were assessed to evaluate the general condition of mice. The triglycerides, total cholesterol content in the liver and liver histopathology, serum lipid profile and serum insulin level, fecal microbiome, hepatic microRNAs and relative target genes were analyzed.

Results

Mice in GP treatment group displayed improved hepatic triglycerides content with lower lipid droplet in hepatocyte and NAFLD activity score. Besides, GP treatment altered the composition of gut microbiota and the relative abundance of some of the key components that are implicated in metabolic disorders, especially phylum Firmicutes (Eubacterium, Blautia, Clostridium and Lactobacillus). Several hepatic microRNAs were downregulated by GP treatment such as miR-130a, miR-34a, miR-29a, miR-199a, among which the expression miR-34a was altered by more than four-fold compared to that of HFD group (3:14). The correlation analysis showed that miR-34a was strongly related to the change of gut microbiota especially phylum Firmicutes (R = 0.796). Additionally, the target genes of miR-34a (HNF4α, PPARα and PPARα) were restored by GP both in mRNA and protein levels.

Conclusion

Our results suggested that GP modulated the gut microbiota and suppressed hepatic miR-34a, which was associated with the amelioration of hepatic steatosis.