Stress-activated miR-21/miR-21* in hepatocytes promotes lipid and glucose metabolic disorders associated with high-fat diet consumption

Multi-omics profiling: the way towards precision medicine in metabolic diseases

Metabolic diseases including type 2 diabetes mellitus (T2DM), non-alcoholic fatty liver disease (NAFLD), and metabolic syndrome (MetS) are alarming health burdens around the world, while therapies for these diseases are far from satisfying as their etiologies are not completely clear yet. T2DM, NAFLD, and MetS are all complex and multifactorial metabolic disorders based on the interactions between genetics and environment. Omics studies such as genetics, transcriptomics, epigenetics, proteomics, and metabolomics are all promising approaches in accurately characterizing these diseases. And the most effective treatments for individuals can be achieved via omics pathways, which is the theme of precision medicine. In this review, we summarized the multi-omics studies of T2DM, NAFLD, and MetS in recent years, provided a theoretical basis for their pathogenesis and the effective prevention and treatment, and highlighted the biomarkers and future strategies for precision medicine.

Circulating miRNA is a useful diagnostic biomarker for nonalcoholic steatohepatitis in nonalcoholic fatty liver disease

Nonalcoholic steatohepatitis (NASH) is considered as a progressive form of nonalcoholic fatty liver disease (NAFLD). To distinguish NASH from nonalcoholic fatty liver (NAFL), we evaluated the diagnostic value of circulating miRNAs. Small RNA sequencing was performed on 12 NAFL patients and 12 NASH patients, and the miRNA expression was compared. After selecting miRNAs for the diagnosis of NASH, we analyzed the diagnostic accuracy of each miRNA and the combination of miRNAs. External validation was performed using quantitative reverse transcription PCR. Among the 2,588 miRNAs, 26 miRNAs significantly increased in the NASH group than in the NAFL group. Among the 26 elevated miRNAs in the NASH group, 8 miRNAs were selected, and in silico analysis was performed. Only four miRNAs (miR-21-5p, miR-151a-3p, miR-192-5p, and miR-4449) showed significant area under the receiver operating characteristic curve (AUC) values for NASH diagnosis. The combination of the four miRNAs showed satisfactory diagnostic accuracy for NASH (AUC 0.875; 95% CI 0.676-0.973). External validation revealed similar diagnostic accuracy for NASH (AUC 0.874; 95% CI 0.724-0.960). NASH represents significantly distinct miRNA expression profile compared with NAFL. The combination of serum circulating miRNAs can be used as a novel biomarker for the NASH diagnosis in NAFLD.

Non-Coding RNAs: Novel Players in Insulin Resistance and Related Diseases

The rising prevalence of metabolic diseases related to insulin resistance (IR) have stressed the urgent need of accurate and applicable tools for early diagnosis and treatment. In the last decade, non-coding RNAs (ncRNAs) have gained growing interest because of their potential role in IR modulation. NcRNAs are variable-length transcripts which are not translated into proteins but are involved in gene expression regulation. Thanks to their stability and easy detection in biological fluids, ncRNAs have been investigated as promising diagnostic and therapeutic markers in metabolic diseases, such as type 2 diabetes mellitus (T2D), obesity and non-alcoholic fatty liver disease (NAFLD). Here we review the emerging role of ncRNAs in the development of IR and related diseases such as obesity, T2D and NAFLD, and summarize current evidence concerning their potential clinical application.

Responses of microRNA and predicted mRNA and enzymatic targets in liver of two salmonids (Oncorhynchus mykiss and Salvelinus fontinalis) following air exposure

The acute stress response is well-characterized, with rainbow trout as a teleost model for physiological and molecular responses. Air exposure, which stimulates an acute stress response, modulates liver microRNAs in rainbow trout; however, these highly conserved non-coding RNAs that bind to mRNA and repress translation, have never been measured in brook trout and it is unknown how miRNA expression responds following air exposure in this less studied salmonid. Our objective was to characterize the effects of air exposure on rainbow and brook trout liver miRNA expression, as well as the mRNA expression and enzyme activity that the miRNAs are predicted to target. Brook and rainbow trout were sampled pre- and 1-, 3-, and 24-h post- a three-minute air exposure. Plasma cortisol, glucose, and lactate were measured. Relative expression of miR-21a-5p, miR-143-3p, let-7a-5p and relative expression and enzyme activities of five predicted targets (pyruvate kinase, glucokinase, citrate synthase, cytochrome c oxidase, and catalase) were measured in liver. Rainbow and brook trout both had increases in plasma cortisol and lactate, while only rainbow trout had significant post-stress increases in plasma glucose. Furthermore, both trout species had increased miR-143-3p and miR-21a-5p relative expression 24-h post-stress. Four of the five enzymes measured had altered activity following stress. Brook trout miRNAs had inverse relative expression with relative catalase mRNA expression and cytochrome c oxidase enzyme activity, but no relationship was found in rainbow trout. Therefore, we have further characterized the transcriptional and enzymatic response to air exposure in two salmonids.

Current Options and Future Directions for NAFLD and NASH Treatment

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide, with a broad spectrum ranging from simple steatosis to advanced stage of nonalcoholic steatohepatitis (NASH). Although there are many undergoing clinical trials for NAFLD treatment, there is no currently approved treatment. NAFLD accounts as a major causing factor for the development of hepatocellular carcinoma (HCC), and its incidence rises accompanying the prevalence of obesity and diabetes. Reprogramming of antidiabetic and anti-obesity medicine is a major treatment option for NAFLD and NASH. Liver inflammation and cellular death, with or without fibrosis account for the progression of NAFLD to NASH. Therefore, molecules and signaling pathways involved in hepatic inflammation, fibrosis, and cell death are critically important targets for the therapy of NAFLD and NASH. In addition, the avoidance of aberrant infiltration of inflammatory cytokines by treating with CCR antagonists also provides a therapeutic option. Currently, there is an increasing number of pre-clinical and clinical trials undergoing to evaluate the effects of antidiabetic and anti-obesity drugs, antibiotics, pan-caspase inhibitors, CCR2/5 antagonists, and others on NAFLD, NASH, and liver fibrosis. Non-invasive serum diagnostic markers are developed for fulfilling the need of diagnostic testing in a large amount of NAFLD cases. Overall, a better understanding of the underlying mechanism of the pathogenesis of NAFLD is helpful to choose an optimized treatment.

Pirfenidone modifies hepatic miRNAs expression in a model of MAFLD/NASH

miRNAs are involved in the development of metabolic associated fatty liver disease (MAFLD) and nonalcoholic steatohepatitis (NASH). We aimed to evaluate modifications by prolonged-release pirfenidone (PR-PFD) on key hepatic miRNAs expression in a MAFLD/NASH model. First, male C57BL/6J mice were randomly assigned into groups and fed with conventional diet (CVD) or high fat and carbohydrate diet (HFD) for 16 weeks. At the end of the eighth week, HFD mice were divided in two and only one half was treated with 300 mg/kg/day of PR-PFD mixed with food. Hepatic expression of miRNAs and target genes that participate in inflammation and lipid metabolism was determined by qRT-PCR and transcriptome by microarrays. Increased hepatic expression of miR-21a-5p, miR-34a-5p, miR-122-5p and miR-103-3p in MAFLD/NASH animals was reduced with PR-PFD. Transcriptome analysis showed that 52 genes involved in lipid and collagen biosynthesis and inflammatory response were downregulated in PR-PFD group. The expression of Il1b, Tnfa, Il6, Tgfb1, Col1a1, and Srebf1 were decreased in PR-PFD treated animals. MAFLD/NASH animals compared to CVD group showed modifications in gene metabolic pathways implicated in lipid metabolic process, inflammatory response and insulin resistance; PR-PFD reversed these modifications.

LIX1-like protein promotes liver cancer progression via miR-21-3p-mediated inhibition of fructose-1,6-bisphosphatase

Limb and CNS expressed 1 like (LIX1L) is over-expressed in several types of tumors. However, the function of LIX1L in glucose metabolism and hepatocellular carcinoma (HCC) progression remains elusive. Here we report that LIX1L is over-expressed in human HCC tissues, which predicts unfavorable prognosis. LIX1L deficiency in vivo significantly attenuated liver cancer initiation in mice. Functional studies indicated that LIX1L overexpression elevated proliferation, migratory, invasive capacities of HCC cells in vitro, and promoted liver cancer growth and metastasis in vivo. LIX1L knockdown up-regulated fructose-1,6-bisphosphatase (FBP1) expression to reduce glucose consumption as well as lactate production. Mechanistically, LIX1L increased miR-21-3p expression, which targeted and suppressed FBP1, thereby promoting HCC growth and metastasis. MiR-21-3p inhibitor could abrogate LIX1L induced enhancement of cell migration, invasion, and glucose metabolism. Inhibition of miR-21-3p suppressed tumor growth in an orthotopic tumor model. Our results establish LIX1L as a critical driver of hepatocarcinogenesis and HCC progression, with implications for prognosis and treatment.

MicroRNAs in the Pathogenesis of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD), or, more accurately, metabolic associated fatty liver disease, accounts for a large proportion of chronic liver disorders worldwide and is closely associated with other conditions such as cardiovascular disease, obesity, and type 2 diabetes mellitus. NAFLD ranges from simple steatosis to nonalcoholic steatohepatitis (NASH) and can progress to cirrhosis and, eventually, also hepatocellular carcinoma. The morbidity and mortality associated with NAFLD are increasing rapidly year on year. Consequently, there is an urgent need to understand the etiology and pathogenesis of NAFLD and identify effective therapeutic targets. MicroRNAs (miRNAs), important epigenetic factors, have recently been proposed to participate in NAFLD pathogenesis. Here, we review the roles of miRNAs in lipid metabolism, inflammation, apoptosis, fibrosis, hepatic stellate cell activation, insulin resistance, and oxidative stress, key factors that contribute to the occurrence and progression of NAFLD. Additionally, we summarize the role of miRNA-enriched extracellular vesicles in NAFLD. These miRNAs may comprise suitable therapeutic targets for the treatment of this condition.

MicroRNAs as regulators, biomarkers and therapeutic targets in liver diseases

MicroRNAs (miRNAs) are small, non-coding RNAs that post-transcriptionally regulate gene expression by binding to specific mRNA targets and promoting their degradation and/or translational inhibition. miRNAs regulate both physiological and pathological liver functions. Altered expression of miRNAs is associated with liver metabolism dysregulation, liver injury, liver fibrosis and tumour development, making miRNAs attractive therapeutic strategies for the diagnosis and treatment of liver diseases. Here, we review recent advances regarding the regulation and function of miRNAs in liver diseases with a major focus on miRNAs that are specifically expressed or enriched in hepatocytes (miR-122, miR-194/192), neutrophils (miR-223), hepatic stellate cells (miR-29), immune cells (miR-155) and in circulation (miR-21). The functions and target genes of these miRNAs are emphasised in alcohol-associated liver disease, non-alcoholic fatty liver disease, drug-induced liver injury, viral hepatitis and hepatocellular carcinoma, as well liver fibrosis and liver failure. We touch on the roles of miRNAs in intercellular communication between hepatocytes and other types of cells via extracellular vesicles in the pathogenesis of liver diseases. We provide perspective on the application of miRNAs as biomarkers for early diagnosis, prognosis and assessment of liver diseases and discuss the challenges in miRNA-based therapy for liver diseases. Further investigation of miRNAs in the liver will help us better understand the pathogeneses of liver diseases and may identify biomarkers and therapeutic targets for liver diseases in the future.

Silibinin improves nonalcoholic fatty liver by regulating the expression of miR‑122: An in vitro and in vivo study

Silibinin is a flavonoid that improves fatty liver and insulin resistance. To elucidate the effect of silibinin on lipid deposition and the potential molecular mechanism, the present study conducted in vivo and in vitro experiments. In the in vivo experiments, mice were randomly divided into control, high‑fat and silibinin groups, while HepG2 cells were randomly divided into control, palmitic acid intervention and silibinin intervention groups. The mRNA, protein and miR‑122 expression associated with hepatic lipid metabolism were detected in each group. The results demonstrated that silibinin reduced the triglyceride content, miR‑122 expression and the mRNA and protein expressions of fatty acid synthase (FAS) and acetyl‑CoA carboxylase (ACC). Silibinin increased the mRNA and protein expression of carnitine palmitoyl transferase 1A (CPT1A). In the present study, HepG2 cells cultured with palmitate were treated with silibinin following overexpression of micro RNA (miR) 122. The results demonstrated that the mRNA and protein expression of FAS and ACC was increased, while that of CPT1A was decreased. Therefore, it could be deduced that silibinin improved lipid metabolism by reducing the expression of miR‑122 and inhibiting the expression of miR‑122 may be a new therapeutic target to improve fatty liver disease.

Vildagliptin Attenuates Myocardial Dysfunction and Restores Autophagy via miR-21/SPRY1/ERK in Diabetic Mice Heart

Aim: Vildagliptin (vild) improves diastolic dysfunction and is associated with a lower relative risk of major adverse cardiovascular events in younger patients. The present study aimed to evaluate whether vild prevents the development of diabetic cardiomyopathy in type 2 diabetic mice and identify its underlying mechanisms. Methods: Type 2 diabetic mouse model was generated using wild-type (WT) (C57BL/6J) and miR-21 knockout mice by treatment with HFD/STZ. Cardiomyocyte-specific miR-21 overexpression was achieved using adeno-associated virus 9. Echocardiography was used to evaluate cardiac function in mice. Morphology, autophagy, and proteins levels in related pathway were analyzed. qRT-PCR was used to detect miR-21. Rat cardiac myoblast cell line (H9c2) cells were transfected with miR-21 mimics and inhibitor to explore the related mechanisms of miR-21 in diabetic cardiomyopathy. Results: Vild restored autophagy and alleviated fibrosis, thereby enhancing cardiac function in DM mice. In addition, miR-21 levels were increased under high glucose conditions. miR-21 knockout DM mice with miR-21 knockout had reduced cardiac hypertrophy and cardiac dysfunction compared to WT DM mice. Overexpression of miR-21 aggravated fibrosis, reduced autophagy, and attenuated the protective effect of vild on cardiac function. In high-glucose-treated H9c2 cells, the downstream effectors of sprouty homolog 1 (SPRY1) including extracellular signal-regulated kinases (ERK) and mammalian target of rapamycin showed significant changes following transfection with miR-21 mimics or inhibitor. Conclusion: The results of our study indicate that vild prevents DCM by restoring autophagy through the miR-21/SPRY1/ERK/mTOR pathway. Therefore, miR-21 is a target in the development of DCM, and vild demonstrates significant potential for clinical application in prevention of DCM.

Heat-stability study of various insulin types in tropical temperature conditions: New insights towards improving diabetes care

Strict storage recommendations for insulin are difficult to follow in hot tropical regions and even more challenging in conflict and humanitarian emergency settings, adding an extra burden to the management of people with diabetes. According to pharmacopeia unopened insulin vials must be stored in a refrigerator (2-8°C), while storage at ambient temperature (25-30°C) is usually permitted for the 4-week usage period during treatment. In the present work we address a critical question towards improving diabetes care in resource poor settings, namely whether insulin is stable and retains biological activity in tropical temperatures during a 4-week treatment period. To answer this question, temperature fluctuations were measured in Dagahaley refugee camp (Northern Kenya) using log tag recorders. Oscillating temperatures between 25 and 37°C were observed. Insulin heat stability was assessed under these specific temperatures which were precisely reproduced in the laboratory. Different commercialized formulations of insulin were quantified weekly by high performance liquid chromatography and the results showed perfect conformity to pharmacopeia guidelines, thus confirming stability over the assessment period (four weeks). Monitoring the 3D-structure of the tested insulin by circular dichroism confirmed that insulin monomer conformation did not undergo significant modifications. The measure of insulin efficiency on insulin receptor (IR) and Akt phosphorylation in hepatic cells indicated that insulin bioactivity of the samples stored at oscillating temperature during the usage period is identical to that of the samples maintained at 2-8°C. Taken together, these results indicate that insulin can be stored at such oscillating ambient temperatures for the usual four-week period of use. This enables the barrier of cold storage during use to be removed, thereby opening up the perspective for easier management of diabetes in humanitarian contexts and resource poor settings.

miR-125b promotes the NF-κB-mediated inflammatory response in NAFLD via directly targeting TNFAIP3

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) has a high incidence and mortality rate, and a rapid course of clinical development. Although miR-125b is closely associated with the pathogenesis of liver fibrosis and hepatocellular carcinoma, the role of miR-125b in NAFLD remains unknown.

METHODS

The levels of TNF-α, IL-6, and IL-1β expression were examined via ELISA assays. Real-time PCR was used to determine the levels of miR-125b and tumor necrosis factor alpha-induced protein 3 (TNFAIP3) expression. The related molecular mechanisms were examined by performing luciferase reporter, western blot, and immunofluorescence assays. Structural changes in the livers of mice with NAFLD were observed via H&E staining.

RESULTS

The levels of TNF-α, IL-6, and IL-1β in NAFLD patients were greatly increased, and miR-125b expression was significantly up-regulated. The phosphorylation of IκBα and p65, and secretion of inflammatory factors were all markedly decreased by miR-125b silencing, but greatly increased by miR-125b overexpression. We also demonstrated that downregulation of TNFAIP3 in NAFLD was negatively correlated with miR-125b. Interestingly, the influence of miR-125b inhibitors on nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB)-mediated inflammatory responses were greatly aggravated by co-treatment with TNFAIP siRNA; however, the opposite results were obtained after treatment with miR-125b mimics and TNFAIP plasmids. Furthermore, the HF-induced liver damage and inflammatory responses were greatly ameliorated by miR-125b inhibitors but further aggravated by co-treatment with TNFAIP3 siRNA.

CONCLUSION

MiR-125b promoted the NF-κB-mediated inflammatory response in NAFLD by directly targeting TNFAIP3, and that mechanism might be target for treating NAFLD.

Role of Neutrophils in the Pathogenesis of Nonalcoholic Steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) includes a spectrum of liver disorders, from fatty liver to nonalcoholic steatohepatitis (NASH), cirrhosis, and hepatocellular carcinoma. Compared with fatty liver, NASH is characterized by increased liver injury and inflammation, in which liver-infiltrating immune cells, with neutrophil infiltration as a hallmark of NASH, play a critical role in promoting the progression of fatty liver to NASH. Neutrophils are the first responders to injury and infection in various tissues, establishing the first line of defense through multiple mechanisms such as phagocytosis, cytokine secretion, reactive oxygen species production, and neutrophil extracellular trap formation; however, their roles in the pathogenesis of NASH remain obscure. The current review summarizes the roles of neutrophils that facilitate the progression of fatty liver to NASH and their involvement in inflammation resolution during NASH pathogenesis. The notion that neutrophils are potential therapeutic targets for the treatment of NASH is also discussed.

The Cell Type-Specific Functions of miR-21 in Cardiovascular Diseases

Cardiovascular diseases are one of the prime reasons for disability and death worldwide. Diseases and conditions, such as hypoxia, pressure overload, infection, and hyperglycemia, might initiate cardiac remodeling and dysfunction by inducing hypertrophy or apoptosis in cardiomyocytes and by promoting proliferation in cardiac fibroblasts. In the vascular system, injuries decrease the endothelial nitric oxide levels and affect the phenotype of vascular smooth muscle cells. Understanding the underlying mechanisms will be helpful for the development of a precise therapeutic approach. Various microRNAs are involved in mediating multiple pathological and physiological processes in the heart. A cardiac enriched microRNA, miR-21, which is essential for cardiac homeostasis, has been demonstrated to act as a cell–cell messenger with diverse functions. This review describes the cell type–specific functions of miR-21 in different cardiovascular diseases and its prospects in clinical therapy.

Host miRNA-21 promotes liver dysfunction by targeting small intestinal Lactobacillus in mice

New evidence shows that host-microbiota crosstalk can be modulated via endogenous miRNAs. We have previously reported that miR-21 ablation protects against liver injury in cholestasis. In this study, we investigated the role of miR-21 in modulating the gut microbiota during cholestasis and its effects in liver dysfunction. Mice lacking miR-21 had reduced liver damage and were protected against small intestinal injury as well as from gut microbiota dysbiosis when subjected to bile duct ligation surgery. The unique microbiota profile of miR-21KO mice was characterized by an increase in Lactobacillus, a key microbiome genus for gut homeostasis. Interestingly, in vitro incubation of synthetic miR-21 directly reduced Lactobacillus load. Moreover, supplementation with Lactobacillus reuteri revealed reduced liver fibrosis in acute bile duct-ligated mice, mimicking the protective effects in miR-21 knockout mice. D-lactate, a main product of Lactobacillus, regulates gut homeostasis that may link with reduced liver fibrosis. Altogether, our results demonstrate that miR-21 promotes liver dysfunction through direct modulation of the gut microbiota and highlight the potential therapeutic effects of Lactobacillus supplementation in gut and liver homeostasis.

Transcriptome and miRNome Analysis Provide New Insight Into Host Lipid Accumulation, Innate Immunity, and Viral Persistence in Hepatitis C Virus Infection in vitro

Hepatitis C virus (HCV)-host cell interaction during infection disturbs cellular homeostasis and culminates in pathological consequences. The processes could be first embodied in gene expression of HCV-infected cells. Here, we investigated transcriptome and miRNA expression (miRNome) alterations in HCV-infected Huh7 cells at 12, 36, and 60 h after infection to systematically explore host responses. The number of deregulated genes in the HCV-infected cells increased with infection duration. The altered biological processes at 36 h were mainly associated with stress and inflammatory response, whereas the most enriched processes at 60 h were predominantly linked to lipid metabolism. Notably, the key genes that participated in lipogenesis were downregulated, and conversely, the genes implicated in fatty acid beta-oxidation were upregulated. Reduced expression of the key genes involved in lipoprotein assembly and secretion pointed to a decreased requirement for and export of lipids, leading to lipid accumulation in HCV-infected hepatocytes. Fluctuation in the expression of host factors, innate immunity genes and transcription factors provided insight into host-directed mechanisms to control viral replication. Furthermore, miRNome presented a comprehensive expression profile of miRNAs in HCV-infected Huh7 cells. The integrated analysis of transcriptome and miRNome suggested that deregulated miR-483, miR-1303, miR-1260a, miR-27a^∗, and miR-21^∗ directly regulated lipid metabolical genes at 60 h. The decreased miR-122 at 60 h was indirectly involved in lipid metabolism and is expected to attenuate rampant replication of HCV and potentially contribute to viral persistence. Our results will help to gain a comprehensive understanding of the molecular mechanisms implicated in HCV-induced pathogenesis.

Genetic Ablation of MiR-22 Fosters Diet-Induced Obesity and NAFLD Development

miR-22 is one of the most abundant miRNAs in the liver and alterations of its hepatic expression have been associated with the development of hepatic steatosis and insulin resistance, as well as cancer. However, the pathophysiological roles of miR-22-3p in the deregulated hepatic metabolism with obesity and cancer remains poorly characterized. Herein, we observed that alterations of hepatic miR-22-3p expression with non-alcoholic fatty liver disease (NAFLD) in the context of obesity are not consistent in various human cohorts and animal models in contrast to the well-characterized miR-22-3p downregulation observed in hepatic cancers. To unravel the role of miR-22 in obesity-associated NAFLD, we generated constitutive Mir22 knockout (miR-22KO) mice, which were subsequently rendered obese by feeding with fat-enriched diet. Functional NAFLD- and obesity-associated metabolic parameters were then analyzed. Insights about the role of miR-22 in NAFLD associated with obesity were further obtained through an unbiased proteomic analysis of miR-22KO livers from obese mice. Metabolic processes governed by miR-22 were finally investigated in hepatic transformed cancer cells. Deletion of Mir22 was asymptomatic when mice were bred under standard conditions, except for an onset of glucose intolerance. However, when challenged with a high fat-containing diet, Mir22 deficiency dramatically exacerbated fat mass gain, hepatomegaly, and liver steatosis in mice. Analyses of explanted white adipose tissue revealed increased lipid synthesis, whereas mass spectrometry analysis of the liver proteome indicated that Mir22 deletion promotes hepatic upregulation of key enzymes in glycolysis and lipid uptake. Surprisingly, expression of miR-22-3p in Huh7 hepatic cancer cells triggers, in contrast to our in vivo observations, a clear induction of a Warburg effect with an increased glycolysis and an inhibited mitochondrial respiration. Together, our study indicates that miR-22-3p is a master regulator of the lipid and glucose metabolism with differential effects in specific organs and in transformed hepatic cancer cells, as compared to non-tumoral tissue.

Rejuvenation of three germ layers tissues by exchanging old blood plasma with saline-albumin

Heterochronic blood sharing rejuvenates old tissues, and most of the studies on how this works focus on young plasma, its fractions, and a few youthful systemic candidates. However, it was not formally established that young blood is necessary for this multi-tissue rejuvenation. Here, using our recently developed small animal blood exchange process, we replaced half of the plasma in mice with saline containing 5% albumin (terming it a "neutral" age blood exchange, NBE) thus diluting the plasma factors and replenishing the albumin that would be diminished if only saline was used. Our data demonstrate that a single NBE suffices to meet or exceed the rejuvenative effects of enhancing muscle repair, reducing liver adiposity and fibrosis, and increasing hippocampal neurogenesis in old mice, all the key outcomes seen after blood heterochronicity. Comparative proteomic analysis on serum from NBE, and from a similar human clinical procedure of therapeutic plasma exchange (TPE), revealed a molecular re-setting of the systemic signaling milieu, interestingly, elevating the levels of some proteins, which broadly coordinate tissue maintenance and repair and promote immune responses. Moreover, a single TPE yielded functional blood rejuvenation, abrogating the typical old serum inhibition of progenitor cell proliferation. Ectopically added albumin does not seem to be the sole determinant of such rejuvenation, and levels of albumin do not decrease with age nor are increased by NBE/TPE. A model of action (supported by a large body of published data) is that significant dilution of autoregulatory proteins that crosstalk to multiple signaling pathways (with their own feedback loops) would, through changes in gene expression, have long-lasting molecular and functional effects that are consistent with our observations. This work improves our understanding of the systemic paradigms of multi-tissue rejuvenation and suggest a novel and immediate use of the FDA approved TPE for improving the health and resilience of older people.

The Emerging Role of MicroRNAs in NAFLD: Highlight of MicroRNA-29a in Modulating Oxidative Stress, Inflammation, and Beyond

Non-alcoholic fatty liver disease (NAFLD) is a common cause of chronic liver disease and ranges from steatosis to steatohepatitis and to liver fibrosis. Lipotoxicity in hepatocytes, elevated oxidative stress and the activation of proinflammatory mediators of Kupffer cells, and fibrogenic pathways of activated hepatic stellate cells can contribute to the development of NAFLD. MicroRNAs (miRs) play a crucial role in the dysregulated metabolism and inflammatory signaling connected with NAFLD and its progression towards more severe stages. Of note, the protective effect of non-coding miR-29a on liver damage and its versatile action on epigenetic activity, mitochondrial homeostasis and immunomodulation may improve our perception of the pathogenesis of NAFLD. Herein, we review the biological functions of critical miRs in NAFLD, as well as highlight the emerging role of miR-29a in therapeutic application and the recent advances in molecular mechanisms underlying its liver protective effect.

Critical Role of microRNA-21 in the Pathogenesis of Liver Diseases

MicroRNAs are small non-coding RNAs that range in length from 18 to 24 nucleotides. As one of the most extensively studied microRNAs, microRNA-21 (miR-21) is highly expressed in many mammalian cell types. It regulates multiple biological functions such as proliferation, differentiation, migration, and apoptosis. In this review, we summarized the mechanism of miR-21 in the pathogenesis of various liver diseases. While it is clear that miR-21 plays an important role in different types of liver diseases, its use as a diagnostic marker for specific liver disease or its therapeutic implication are not ready for prime time due to significant variability and heterogeneity in the expression of miR-21 in different types of liver diseases depending on the studies. Additional studies to further define miR-21 functions and its mechanism in association with each type of chronic liver diseases are needed before we can translate the bedside observations into clinical settings.

Guidelines and Considerations for Metabolic Tolerance Tests in Mice

The epidemic of the century, Diabetes Mellitus (DM) is continuously rising. Intensive research is urgently needed whereby experimental models represent an essential tool to optimise the diagnostic strategy and to improve therapy. In this review, we describe the central principles of the metabolic tests available in order to study glucose and insulin homeostasis in mice, focusing on the most widely used - the glucose and insulin tolerance tests. We provide detailed experimental procedures as well as the practical implementation of these methods and discuss the main factors that should be taken into account when using this methodology.

miRNAs and NAFLD: from pathophysiology to therapy

Non-alcoholic fatty liver disease (NAFLD) is associated with a thorough reprogramming of hepatic metabolism. Epigenetic mechanisms, in particular those associated with deregulation of the expressions and activities of microRNAs (miRNAs), play a major role in metabolic disorders associated with NAFLD and their progression towards more severe stages of the disease. In this review, we discuss the recent progress addressing the role of the many facets of complex miRNA regulatory networks in the development and progression of NAFLD. The basic concepts and mechanisms of miRNA-mediated gene regulation as well as the various setbacks encountered in basic and translational research in this field are debated. miRNAs identified so far, whose expressions/activities are deregulated in NAFLD, and which contribute to the outcomes of this pathology are further reviewed. Finally, the potential therapeutic usages in a short to medium term of miRNA-based strategies in NAFLD, in particular to identify non-invasive biomarkers, or to design pharmacological analogues/inhibitors having a broad range of actions on hepatic metabolism, are highlighted.

miR-21 promotes non-small cell lung cancer cells growth by regulating fatty acid metabolism

Background

Lung cancer is one of the most common malignant tumors worldwide. CD36 is a receptor for fatty acids and plays an important role in regulating fatty acid metabolism, which is closely related to tumorigenesis and development. The regulation of miR-21 and its role in tumorigenesis have been extensively studied in recent years. However, the relationship between miR-21 and CD36 regulated fatty acid metabolism in human non-small cell lung cancer remains unknown.

Methods

In this study, lentivirus transfection, qRT-PCR, cell migration, immunofluorescence, and western blot were used to examine the relationship between miR-21 and CD36 regulated fatty acid metabolism and the regulation role of miR-21 in human non-small cell lung cancer.

Results

This study demonstrated that up-regulation of miR-21 promoted cell migration and cell growth in human non-small cell lung cancer cells. Moreover, the intracellular contents of lipids including cellular content of phospholipids, neutral lipids content, cellular content of triglycerides were significantly increased following miR-21 mimic treatment compared with control, and the levels of key lipid metabolic enzymes FASN, ACC1 and FABP5 were obviously enhanced in human non-small cell lung cancer cells. Furthermore, down-regulation of CD36 suppressed miR-21 regulated cell growth, migration and intracellular contents of lipids in human non-small cell lung cancer cells, which suggested that miR-21 promoted cell growth and migration of human non-small cell lung cancer cells through CD36 mediated fatty acid metabolism. Inhibition of miR-21 was revealed to inhibit cell growth, migration, intracellular contents of lipids, and CD36 protein expression level in human non-small cell lung cancer cells. In addition, PPARGC1B was a direct target of miR-21, and down-regulation of PPARGC1B reversed the inhibition of CD36 expression induced by miR-21 inhibitor.

Conclusions

These results explored the mechanism of miR-21 promoted non-small cell lung cancer and might provide a novel therapeutic method in treating non-small cell lung cancer in clinic.

Activation of the oncogenic miR-21-5p promotes HCV replication and steatosis induced by the viral core 3a protein

BACKGROUND & AIMS

miR-21-5p is a potent oncogenic microRNA targeting many key tumour suppressors including phosphatase and tensin homolog (PTEN). We recently identified PTEN as a key factor modulated by hepatitis C virus (HCV) to promote virion egress. In hepatocytes, expression of HCV-3a core protein was sufficient to downregulate PTEN and to trigger lipid droplet accumulation. Here, we investigated whether HCV controls PTEN expression through miR-21-5p-dependent mechanisms to trigger steatosis in hepatocytes and to promote HCV life cycle.

METHODS

MiR-21-5p expression in HCV-infected patients was evaluated by transcriptome meta-analysis. HCV replication and viral particle production were investigated in Jc1-infected Huh-7 cells after miR-21-5p inhibition. PTEN expression and steatosis were assessed in HCV-3a core protein-expressing Huh-7 cells and in mouse primary hepatocytes having miR-21-5p inhibited or genetically deleted respectively. HCV-3a core-induced steatosis was assessed in vivo in Mir21a knockout mice.

RESULTS

MiR-21-5p expression was significantly increased in hepatic tissues from HCV-infected patients. Infection by HCV-Jc1, or transduction with HCV-3a core, upregulated miR-21-5p expression and/or activity in Huh-7 cells. miR-21-5p inhibition decreased HCV replication and release of infectious virions by Huh-7 cells. HCV-3a core-induced PTEN downregulation and steatosis were further prevented in Huh-7 cells following miR-21-5p inhibition or in Mir21a knockout mouse primary hepatocytes. Finally, steatosis induction by AAV8-mediated HCV-3a core expression was reduced in vivo in Mir21a knockout mice.

CONCLUSION

MiR-21-5p activation by HCV is a key molecular step, promoting both HCV life cycle and HCV-3a core-induced steatosis and may be among the molecular changes induced by HCV-3a to promote carcinogenesis.

Social status regulates the hepatic miRNAome in rainbow trout: Implications for posttranscriptional regulation of metabolic pathways

Juvenile rainbow trout develop social hierarchies when held in dyads, and the development of socially subordinate (SS) and social dominance (SD) phenotypes in this context has been linked to specific changes in the hepatic energy metabolism of all major macronutrients. Following our recently reported finding that transcript abundance of drosha, a key component of the microRNA (miRNA) biogenesis pathway, is increased in paired juvenile rainbow trout irrespective of social status compared to socially isolated (SI) controls, we here determined global changes of the hepatic miRNA pathway genes in detail at the transcript and protein level. Both SD and SS rainbow trout exhibited increased Ago2 protein abundance compared to SI rainbow trout, suggesting that hepatic miRNA function is increased in rainbow trout maintained in dyads. Given the well-described differences in hepatic intermediary metabolism between SD and SS rainbow trout, and the important role of miRNAs in the posttranscriptional regulation of metabolic pathways, we also identified changes in hepatic miRNA abundance between SS and SD rainbow trout using small RNA next generation sequencing. We identified a total of 24 differentially regulated miRNAs, with 15 miRNAs that exhibited increased expression, and 9 miRNAs that exhibited decreased expression in the liver of SS trout compared to SD trout. To identify potential miRNA-dependent posttranscriptional regulatory pathways important for social status-dependent regulation of hepatic metabolism in rainbow trout, we used an in silico miRNA target prediction and pathway enrichment approach. We identified enrichment for pathways related to metabolism of carbohydrates, lipids and proteins in addition to organelle-specific processes involved in energy metabolism, especially mitochondrial fusion and fission. Select predicted miRNA-mRNA target pairs within these categories were quantitatively analyzed by real-time RT-PCR to validate candidates for future studies that will probe the functional metabolic roles of specific hepatic miRNAs in the development of SD and SS metabolic phenotypes.

MiR-21-3p Plays a Crucial Role in Metabolism Alteration of Renal Tubular Epithelial Cells during Sepsis Associated Acute Kidney Injury via AKT/CDK2-FOXO1 Pathway

Objective

Sepsis and associated acute kidney injury (SAKI) are determined to be closely related to poor prognosis. Because the metabolic alterations of tubular epithelial cells (TECs) are crucial for the occurrence and development of SAKI, we carried out this present study to identify the metabolism changes of TECs during SAKI and relevant mechanisms.

Methods

Rat SAKI model and rat tubular epithelial cell line were used in our study. ELISA was used to determine the serum cytokines levels. Protein expressions were examined with Western-Blotting and the transcriptions of RNAs were determined with qRT-PCR. ADP/ATP assay and Oil Red O staining were used to examine the energy and lipid metabolism, respectively. Dual-luciferase reporter assay was carried out to determine the interactions between miRNA and specific proteins. Cell cycle arrest and apoptosis were determined with flow cytometry.

Results

Sepsis and AKI were induced 12 h after CLP. Energy and lipid metabolism reduced significantly while FOXO1 levels increased remarkably in TECs during SAKI. The expressions of both AKT and CDK2 and the transcriptions of relevant mRNAs reduced significantly in TECs during SAKI while miR-21-3p expression increased remarkably. Both AKT and CDK2 were determined as the direct targets of miR-21-3p. Furthermore, by in vitro experiments, it was demonstrated that FOXO1 levels were regulated by miR-21-3p in TECs via AKT/CDK2 and AKT/CDK2-FOXO1 pathway was crucial in the regulations of miR-21-3p on lipid metabolism, cell cycle arrest, and apoptosis of TECs.

Conclusions

MiR-21-3p mediates metabolism and cell fate alterations of TECs via manipulating AKT/CDK2-FOXO1 pathway, and that is crucial in the regulation of energy metabolism of TECs during SAKI.

Associations of blood levels of trace elements and heavy metals with metabolic syndrome in Chinese male adults with microRNA as mediators involved

Metabolic syndrome (MetS) is a global health problem with an increasing prevalence. However, effects of trace elements and heavy metals on MetS and the mechanism underlying this effect are poorly understood. A preliminary cross-sectional study was conducted in 2015. Significantly higher blood concentrations of lead (Pb), cadmium (Cd), copper (Cu), and selenium (Se) were observed in the MetS group. With a priori adjustment for age, the concentration of Cu and Se in the blood was associated with a 2.56 - fold [95% confidence interval (CI), 1.11, 5.92] and 3.31 - fold (95% CI, 1.4, 7.82) increased risk of MetS, respectively. Moreover, increased blood Se concentrations were associated with body mass index (BMI) [odds ratio (OR): 2.56; 95% CI, 1.11, 5.93], high blood pressure [for both systolic and diastolic blood pressures (SBP and DBP); OR: 3.82; 95% CI, 1.47, 7.31 for SBP and OR: 2.56; 95% CI, 1.18, 5.59 for DBP], and hypertriglyceridemia (OR: 3.3; 95% CI, 1.51, 7.2). In addition, the expression of miR-21-5p, miR-122-5p, and miR-146a-5p was significantly higher in subjects with MetS than those without MetS. Increased expression of miR-21-5p was significantly associated with increased SBP (β = 5.28; 95% CI, 0.63, 9.94) and DBP (β = 4.17; 95% CI, 0.68, 7.66). Moreover, Cu was positively associated with miR-21-5p (β = 3.02; 95% CI, 0.07, 5.95), whereas Se was positively associated with miR-122-5p (β = 2.7; 95% CI, 0.64, 4.76). The bootstrapping mediation models indicated that miR-21-5p partially mediated the relationships between Cu level and SBP/DBP. This study suggested that Cu and Se were both associated with MetS, and miR-21-5p participated in the development of MetS associated with Cu.

Eicosapentaenoic Acid Improves Hepatic Metabolism and Reduces Inflammation Independent of Obesity in High-Fat-Fed Mice and in HepG2 Cells

The prevalence of nonalcoholic fatty liver disease (NAFLD) is increasing worldwide, concurrent with increased obesity. Thus, there is urgent need for research that can lead to effective NAFLD prevention/treatment strategies. Omega-3 polyunsaturated fatty acids (n-3 PUFAs), including eicosapentaenoic acid (EPA), improve inflammation- and dyslipidemia-related metabolic disorders; however, mechanisms mediating the benefits of n-3 PUFAs in NAFLD treatment are less understood. We previously reported that EPA reversed obesity-induced hepatic steatosis in high-fat (HF)-fed B6 mice. Utilizing a combination of biochemical analyses of liver tissues from HF and HF-EPA-fed mice and a series of in vitro studies in tumor necrosis factor-alpha (TNF-α)-stimulated HepG2 cells, we dissect the mechanistic effects of EPA in reducing hepatic steatosis, including the role of EPA-targeted microRNAs (miRNA). With EPA, hepatic lipid metabolism was improved in HF-EPA mice, as indicated by decreased protein and messenger RNA (mRNA) levels of fatty acid synthase (FASN) and acetyl-CoA carboxylase (Acaca) gene, and increased mRNA levels for the peroxisome proliferator activated receptor-α (Pparα), and carnitine palmitoyltransferase (Cpt) 1a and 2 genes in the HF-EPA mice. Additionally, inflammation was reduced, as shown by decreased tumor necrosis factor-alpha (Tnfα) gene expression. Accordingly, EPA also significantly reduced FASN and ACACA mRNAs in human HepG2 cells. Glycolysis, estimated by extracellular acidification rate, was significantly reduced in HepG2 cells treated with EPA vs. vehicle. Furthermore, we identified several miRNAs that are regulated by EPA in mouse liver, including miR-19b-3p, miR-21a-5p, and others, which target lipid metabolism and inflammatory pathways. In conclusion, our findings provide novel mechanistic evidence for beneficial effects of EPA in NAFLD, through the identification of specific genes and miRNAs, which may be further exploited as future NAFLD therapies.

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.

A New Insight into the Roles of MiRNAs in Metabolic Syndrome

Metabolic syndrome (MetS), which includes several clinical components such as abdominal obesity, insulin resistance (IR), dyslipidemia, microalbuminuria, hypertension, proinflammatory state, and oxidative stress (OS), has become a global epidemic health issue contributing to a high risk of type 2 diabetes mellitus (T2DM). In recent years, microRNAs (miRNAs), used as noninvasive biomarkers for diagnosis and therapy, have aroused global interest in complex processes in health and diseases, including MetS and its components. MiRNAs can exist stably in serum, liver, skeletal muscle (SM), heart muscle, adipose tissue (AT), and βcells, because of their ability to escape the digestion of RNase. Here we first present an overall review on recent findings of the relationship between miRNAs and several main components of MetS, such as IR, obesity, diabetes, lipid metabolism, hypertension, hyperuricemia, and stress, to illustrate the targeting proteins or relevant pathways that are involved in the progress of MetS and also help us find promising novel diagnostic and therapeutic strategies.

Targeting a phospho-STAT3-miRNAs pathway improves vesicular hepatic steatosis in an in vitro and in vivo model

Non-alcoholic fatty liver disease (NAFLD) is a leading cause of chronic liver disease. Although genetic predisposition and epigenetic factors contribute to the development of NAFLD, our understanding of the molecular mechanism involved in the pathogenesis of the disease is still emerging. Here we investigated a possible role of a microRNAs-STAT3 pathway in the induction of hepatic steatosis. Differentiated HepaRG cells treated with the fatty acid sodium oleate (fatty dHepaRG) recapitulated features of liver vesicular steatosis and activated a cell-autonomous inflammatory response, inducing STAT3-Tyrosine-phosphorylation. With a genome-wide approach (Chromatin Immunoprecipitation Sequencing), many phospho-STAT3 binding sites were identified in fatty dHepaRG cells and several STAT3 and/or NAFLD-regulated microRNAs showed increased expression levels, including miR-21. Innovative CARS (Coherent Anti-Stokes Raman Scattering) microscopy revealed that chemical inhibition of STAT3 activity decreased lipid accumulation and deregulated STAT3-responsive microRNAs, including miR-21, in lipid overloaded dHepaRG cells. We were able to show in vivo that reducing phospho-STAT3-miR-21 levels in C57/BL6 mice liver, by long-term treatment with metformin, protected mice from aging-dependent hepatic vesicular steatosis. Our results identified a microRNAs-phosphoSTAT3 pathway involved in the development of hepatic steatosis, which may represent a molecular marker for both diagnosis and therapeutic targeting.

Genetics and epigenetics of NAFLD and NASH: Clinical impact

Non-alcoholic fatty liver disease (NAFLD) is now recognised as the most common liver disease worldwide. It encompasses a broad spectrum of conditions, from simple steatosis, through non-alcoholic steatohepatitis, to fibrosis and ultimately cirrhosis and hepatocellular carcinoma. A hallmark of NAFLD is the substantial inter-patient variation in disease progression. NAFLD is considered a complex disease trait such that interactions between the environment and a susceptible polygenic host background determine disease phenotype and influence progression. Recent years have witnessed multiple genome-wide association and large candidate gene studies, which have enriched our understanding of the genetic basis of NAFLD. Notably, the I148M PNPLA3 variant has been identified as the major common genetic determinant of NAFLD. Variants with moderate effect size in TM6SF2, MBOAT7 and GCKR have also been shown to have a significant contribution. The premise for this review is to discuss the status of research into important genetic and epigenetic modifiers of NAFLD progression. The potential to translate the accumulating wealth of genetic data into the design of novel therapeutics and the clinical implementation of diagnostic/prognostic biomarkers will be explored. Finally, personalised medicine and the opportunities for future research and challenges in the immediate post genetics era will be illustrated and discussed.

miRNA-21 ablation protects against liver injury and necroptosis in cholestasis

Inhibition of microRNA-21 (miR-21) prevents necroptosis in the mouse pancreas. Necroptosis contributes to hepatic necro-inflammation in the common bile duct ligation (BDL) murine model. We aimed to evaluate the role of miR-21 in mediating deleterious processes associated with cholestasis. Mechanistic studies established a functional link between miR-21 and necroptosis through cyclin-dependent kinase 2-associated protein 1 (CDK2AP1). miR-21 expression increased in the liver of primary biliary cholangitis (PBC) patients and BDL wild-type (WT) mice at both 3 and 14 days. Notably, under BDL, miR-21 ^-/- mice displayed decreased liver injury markers in serum compared with WT mice, accompanied by reduced hepatocellular degeneration, oxidative stress and fibrosis. Hallmarks of necroptosis were decreased in the liver of BDL miR-21 ^-/- mice, via relieved repression of CDK2AP1. Further, miR-21 ^-/- mice displayed improved adaptive response of bile acid homeostasis. In conclusion, miR-21 ablation ameliorates liver damage and necroptosis in BDL mice. Inhibition of miR-21 should arise as a promising approach to treat cholestasis.

Peroxisome Proliferator-Activated Receptors Associated with Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is rapidly becoming a major cause of chronic liver disease worldwide. Concurrent to an increase in NAFLD prevalence, there is an increase in the obesity epidemic and the correlated insulin-resistant state. It is a challenge to diagnose NAFLD because many patients are asymptomatic until the later stages of disease. The most common symptoms include fatigue, malaise, and discomfort in the right upper quadrant. The major and most accurate tool to clinically diagnose NAFLD is a liver biopsy, followed by histological analysis. However, this procedure is invasive and often carries a high risk of complications. Currently, there are no officially approved medications for the treatment of NAFLD. Although lifestyle modifications with proper diet and exercise have been shown to be beneficial, this has been difficult to achieve and sustain for many patients. Effective pharmacological treatments are still lacking; therefore, additional research to identify novel drugs is clearly warranted. PPARs are promising drug targets for the management of NAFLD and its related conditions of type 2 diabetes mellitus and cardiovascular disease. In this review, we provide an overview of recent studies on the association of PPARs and NAFLD.

Systems genetics identifies a co-regulated module of liver microRNAs associated with plasma LDL cholesterol in murine diet-induced dyslipidemia

Chronically altered levels of circulating lipids, termed dyslipidemia, is a significant risk factor for a number of metabolic and cardiovascular morbidities. MicroRNAs (miRNAs) have emerged as important regulators of lipid balance, have been implicated in dyslipidemia, and have been proposed as candidate therapeutic targets in lipid-related disorders including atherosclerosis. A major limitation of most murine studies of miRNAs in lipid metabolic disorders is that they have been performed in just one (or very few) inbred strains, such as C57BL/6. Moreover, although individual miRNAs have been associated with lipid phenotypes, it is well understood that miRNAs likely work together in functional modules. To address these limitations, we implemented a systems genetics strategy using the Diversity Outbred (DO) mouse population. Specifically, we performed gene and miRNA expression profiling in the livers from ~300 genetically distinct DO mice after 18 wk on either a high-fat/high-cholesterol diet or a high-protein diet. Large-scale correlative analysis of these data with a wide range of cardio-metabolic end points revealed a co-regulated module of miRNAs significantly associated with circulating low-density lipoprotein cholesterol (LDL-C) levels. The hubs of this module were identified as miR-199a, miR-181b, miR-27a, miR-21_-_1, and miR-24. In sum, we demonstrate that a high-fat/high-cholesterol diet robustly rewires the miRNA regulatory network, and we identify a small group of co-regulated miRNAs that may exert coordinated effects to control circulating LDL-C.

MicroRNA-21 regulates peroxisome proliferator-activated receptor alpha, a molecular mechanism of cardiac pathology in Cardiorenal Syndrome Type 4

Cardiovascular events are the leading cause of death in patients with chronic kidney disease (CKD), although the pathological mechanisms are poorly understood. Here we longitudinally characterized left ventricle pathology in a 5/6 nephrectomy rat model of CKD and identify novel molecular mediators. Next-generation sequencing of left ventricle mRNA and microRNA (miRNA) was performed at physiologically distinct points in disease progression, identifying alterations in genes in numerous immune, lipid metabolism, and inflammatory pathways, as well as several miRNAs. MiRNA miR-21-5p was increased in our dataset and has been reported to regulate many identified pathways. Suppression of miR-21-5p protected rats with 5/6 nephrectomy from developing left ventricle hypertrophy and improved left ventricle function. Next-generation mRNA sequencing revealed that miR-21-5p suppression altered gene expression in peroxisome proliferator-activated receptor alpha (PPARα) regulated pathways in the left ventricle. PPARα, a miR-21-5p target, is the primary PPAR isoform in the heart, importantly involved in regulating fatty acid metabolism. Therapeutic delivery of low-dose PPARα agonist (clofibrate) to rats with 5/6 nephrectomy improved cardiac function and prevented left ventricle dilation. Thus, comprehensive characterization of left ventricle molecular changes highlights the involvement of numerous signaling pathways not previously explored in CKD models and identified PPARα as a potential therapeutic target for CKD-related cardiac dysfunction.

MicroRNA-148a deficiency promotes hepatic lipid metabolism and hepatocarcinogenesis in mice

miRNAs are involved in many physiologic and disease processes by virtue of degrading specific mRNAs or inhibiting their translation. miR-148a has been implicated in the control of tumor growth and cholesterol and triglyceride homeostasis using in vitro or in vivo gene expression- and silencing-based approaches. Here miR-148a knockout (KO) mice were used to investigate the intrinsic role of miR-148a in liver physiology and hepatocarcinogenesis in mice. miR-148a downregulation was found to be correlated with poor clinical outcomes in hepatocellular carcinoma (HCC) patients. Under regular chow diet (RCD) or high fat diet (HFD), miR-148a deletion significantly accelerated DEN-induced hepatocarcinogenesis in mice. Mechanistically, miR-148a deletion promotes lipid metabolic disorders in mice. Moreover, restoration of miR-148a reversed these defects. Finally, miR-148a was found to directly inhibit several key regulators of hepatocarcinogenesis and lipid metabolism. These findings reveal crucial roles for miR-148a in the hepatic lipid metabolism and hepatocarcinogenesis. They further identify miR-148a as a potential therapeutic target for certain liver diseases, including cancer.

Folate cycle enzyme MTHFD1L confers metabolic advantages in hepatocellular carcinoma

Cancer cells preferentially utilize glucose and glutamine, which provide macromolecules and antioxidants that sustain rapid cell division. Metabolic reprogramming in cancer drives an increased glycolytic rate that supports maximal production of these nutrients. The folate cycle, through transfer of a carbon unit between tetrahydrofolate and its derivatives in the cytoplasmic and mitochondrial compartments, produces other metabolites that are essential for cell growth, including nucleotides, methionine, and the antioxidant NADPH. Here, using hepatocellular carcinoma (HCC) as a cancer model, we have observed a reduction in growth rate upon withdrawal of folate. We found that an enzyme in the folate cycle, methylenetetrahydrofolate dehydrogenase 1-like (MTHFD1L), plays an essential role in support of cancer growth. We determined that MTHFD1L is transcriptionally activated by NRF2, a master regulator of redox homeostasis. Our observations further suggest that MTHFD1L contributes to the production and accumulation of NADPH to levels that are sufficient to combat oxidative stress in cancer cells. The elevation of oxidative stress through MTHFD1L knockdown or the use of methotrexate, an antifolate drug, sensitizes cancer cells to sorafenib, a targeted therapy for HCC. Taken together, our study identifies MTHFD1L in the folate cycle as an important metabolic pathway in cancer cells with the potential for therapeutic targeting.

miR-21 ablation and obeticholic acid ameliorate nonalcoholic steatohepatitis in mice

microRNAs were recently suggested to contribute to the pathogenesis of nonalcoholic fatty liver disease (NAFLD), a disease lacking specific pharmacological treatments. In that regard, nuclear receptors are arising as key molecular targets for the treatment of nonalcoholic steatohepatitis (NASH). Here we show that, in a typical model of NASH-associated liver damage, microRNA-21 (miR-21) ablation results in a progressive decrease in steatosis, inflammation and lipoapoptosis, with impairment of fibrosis. In a complementary fast food (FF) diet NASH model, mimicking features of the metabolic syndrome, miR-21 levels increase in both liver and muscle, concomitantly with decreased expression of peroxisome proliferator-activated receptor α (PPARα), a key miR-21 target. Strikingly, miR-21 knockout mice fed the FF diet supplemented with farnesoid X receptor (FXR) agonist obeticholic acid (OCA) display minimal steatosis, inflammation, oxidative stress and cholesterol accumulation. In addition, lipoprotein metabolism was restored, including decreased fatty acid uptake and polyunsaturation, and liver and muscle insulin sensitivity fully reinstated. Finally, the miR-21/PPARα axis was found amplified in liver and muscle biopsies, and in serum, of NAFLD patients, co-substantiating its role in the development of the metabolic syndrome. By unveiling that miR-21 abrogation, together with FXR activation by OCA, significantly improves whole body metabolic parameters in NASH, our results highlight the therapeutic potential of nuclear receptor multi-targeting therapies for NAFLD.

Milk's Role as an Epigenetic Regulator in Health and Disease

It is the intention of this review to characterize milk's role as an epigenetic regulator in health and disease. Based on translational research, we identify milk as a major epigenetic modulator of gene expression of the milk recipient. Milk is presented as an epigenetic "doping system" of mammalian development. Milk exosome-derived micro-ribonucleic acids (miRNAs) that target DNA methyltransferases are implicated to play the key role in the upregulation of developmental genes such as FTO, INS, and IGF1. In contrast to miRNA-deficient infant formula, breastfeeding via physiological miRNA transfer provides the appropriate signals for adequate epigenetic programming of the newborn infant. Whereas breastfeeding is restricted to the lactation period, continued consumption of cow's milk results in persistent epigenetic upregulation of genes critically involved in the development of diseases of civilization such as diabesity, neurodegeneration, and cancer. We hypothesize that the same miRNAs that epigenetically increase lactation, upregulate gene expression of the milk recipient via milk-derived miRNAs. It is of critical concern that persistent consumption of pasteurized cow's milk contaminates the human food chain with bovine miRNAs, that are identical to their human analogs. Commercial interest to enhance dairy lactation performance may further increase the epigenetic miRNA burden for the milk consumer.

MicroRNAs-Dependent Regulation of PPARs in Metabolic Diseases and Cancers

Peroxisome proliferator-activated receptors (PPARs) are a family of ligand-dependent nuclear receptors, which control the transcription of genes involved in energy homeostasis and inflammation and cell proliferation/differentiation. Alterations of PPARs' expression and/or activity are commonly associated with metabolic disorders occurring with obesity, type 2 diabetes, and fatty liver disease, as well as with inflammation and cancer. Emerging evidence now indicates that microRNAs (miRNAs), a family of small noncoding RNAs, which fine-tune gene expression, play a significant role in the pathophysiological mechanisms regulating the expression and activity of PPARs. Herein, the regulation of PPARs by miRNAs is reviewed in the context of metabolic disorders, inflammation, and cancer. The reciprocal control of miRNAs expression by PPARs, as well as the therapeutic potential of modulating PPAR expression/activity by pharmacological compounds targeting miRNA, is also discussed.

The role of microRNAs in liver injury at the crossroad between hepatic cell death and regeneration

The liver fulfills critical metabolic functions, such as controlling blood sugar and ammonia levels, and is of central importance for lipid metabolism and detoxification of environmental and chemical agents, including drugs. Liver injuries of different etiology can elicit a spectrum of responses. Some hepatocytes initiate molecular programs resulting in cell death, whereas others undergo cellular divisions to regenerate the damaged organ. Interestingly, recent research indicates that microRNAs serve as very rapid as well as long-term regulators in these processes. In this review, we discuss their importance in liver disease etiology and progression as well as for therapy with particular focus on metabolic and inflammatory conditions. Furthermore, we highlight the central role of microRNAs in controlling hepatocyte differentiation and plasticity, which are required for successful regeneration, but under certain conditions, such as chronic liver insults, can result in the formation of hepatocellular carcinoma.