MicroRNAs-Dependent Regulation of PPARs in Metabolic Diseases and Cancers

miRNA‑21 promotes the progression of acute liver failure via the KLF6/autophagy/IL‑23 signaling pathway

Acute liver failure (ALF) is a complex syndrome characterized by overactivation of innate immunity, and the recruitment and differentiation of immune cells at inflammatory sites. The present study aimed to explore the role of microRNA (miRNA/miR)‑21 and its potential mechanisms underlying inflammatory responses in ALF. Baseline serum miR‑21 was analyzed in patients with ALF and healthy controls. In addition, miR‑21 antagomir was injected via the tail vein into C57BL/6 mice, and lipopolysaccharide/D‑galactosamine (LPS/GalN) was injected into mice after 48 h. The expression levels of miR‑21, Krüppel‑like‑factor‑6 (KLF6), autophagy‑related proteins and interleukin (IL)‑23, and hepatic pathology were then assessed in the liver tissue. Furthermore, THP‑1‑derived macrophages were transfected with a miRNA negative control, miR‑21 inhibitor, miR‑21 mimics or KLF6 overexpression plasmid, followed by treatment with or without rapamycin, and the expression levels of miR‑21, KLF6, autophagy‑related proteins and IL‑23 were evaluated. The results revealed that baseline serum miR‑21 levels were significantly upregulated in patients with ALF. In addition, LPS/GalN‑induced ALF was attenuated in the antagomir‑21 mouse group. KLF6 was identified as a target of miR‑21‑5p with one putative seed match site identified by TargetScan. A subsequent luciferase activity assay demonstrated a direct interaction between miR‑21‑5p and the 3'‑UTR of KLF6 mRNA. Further experiments suggested that miR‑21 promoted the expression of IL‑23 via inhibiting KLF6, which regulated autophagy. In conclusion, in the present study, baseline serum miR‑21 levels were highly upregulated in patients with ALF, antagomir‑21 attenuated LPS/GalN‑induced ALF in a mouse model, and miR‑21 could promote the expression of IL‑23 via inhibiting KLF6.

Atrial natriuretic peptide signaling co-regulates lipid metabolism and ventricular conduction system gene expression in the embryonic heart

It has been shown that atrial natriuretic peptide (ANP) and its high affinity receptor (NPRA) are involved in the formation of ventricular conduction system (VCS). Inherited genetic variants in fatty acid oxidation (FAO) genes are known to cause conduction abnormalities in newborn children. Although the effect of ANP on energy metabolism in noncardiac cell types is well documented, the role of lipid metabolism in VCS cell differentiation via ANP/NPRA signaling is not known. In this study, histological sections and primary cultures obtained from E11.5 mouse ventricles were analyzed to determine the role of metabolic adaptations in VCS cell fate determination and maturation. Exogenous treatment of E11.5 ventricular cells with ANP revealed a significant increase in lipid droplet accumulation, FAO and higher expression of VCS marker Cx40. Using specific inhibitors, we further identified PPARγ and FAO as critical downstream regulators of ANP-mediated regulation of metabolism and VCS formation.

Childhood obesity, metabolic syndrome, and oxidative stress: microRNAs go on stage

The incidence of childhood obesity and metabolic syndrome has grown notably in the last years, becoming major public health burdens in developed countries. Nowadays, oxidative stress is well-recognized to be closely associated with the onset and progression of several obesity-related complications within the framework of a complex crosstalk involving other intertwined pathogenic events, such as inflammation, insulin disturbances, and dyslipidemia. Thus, understanding the molecular basis behind these oxidative dysregulations could provide new approaches for the diagnosis, prevention, and treatment of childhood obesity and associated disorders. In this respect, the transcriptomic characterization of miRNAs bares great potential because of their involvement in post-transcriptional modulation of genetic expression. Herein, we provide a comprehensive literature revision gathering state-of-the-art research into the association between childhood obesity, metabolic syndrome, and miRNAs. We put special emphasis on the potential role of miRNAs in modulating obesity-related pathogenic events, with particular focus on oxidative stress.

Does exercise influence skeletal muscle by modulating mitochondrial functions via regulating MicroRNAs? A systematic review

BACKGROUND

Sarcopenia is the accelerated loss of muscle mass, strength and function. Mitochondrial dysfunction was related to the progression of sarcopenia; meanwhile, microRNAs were regarded as core roles in regulating mitochondrial function. Physical exercise is a well-accepted approach to attenuate sarcopenia, yet very few studies depict the molecular mechanisms. The aim of this systematic review is to explore the potential relationships among physical exercise, mitochondrial function, and microRNAs, which may give new insight for retarding sarcopenia.

METHODS

A systematic literature search was performed in PubMed, Embase and Web of Science. The keywords were combined as "(microRNA OR miR) AND mitochondri* AND muscle AND exercise" and searched in all fields. PRISMA guidelines were followed. Information was extracted from the included studies for review.

RESULTS

In this review, 18 preclinical studies and 5 clinical studies were included. Most of the included studies suggested that effective physical exercise had positive effects on mitochondrial functions by regulating microRNAs. The results showed that 12 microRNAs improved mitochondrial functions, while 18 microRNAs suppressed them. Meanwhile, the results showed that 5 microRNAs improved muscle performance.

CONCLUSIONS

This systematic review provides an up-to-date sequential overview and highlights the potential relationship among exercise, mitochondrial function, and microRNAs in muscle. Meanwhile, evidence revealed that physical exercise can improve muscle performance by up-regulating mitochondrial functions, especially mitochondrial biogenesis, through modulating microRNAs.

Early microRNA responses in rodent liver mediated by furan exposure establish dose thresholds for later adverse outcomes

To reduce reliance on long-term in vivo studies, short-term data linking early molecular-based measurements to later adverse health effects is needed. Although transcriptional-based benchmark dose (BMDT) modeling has been used to estimate potencies and stratify chemicals based on potential to induce later-life effects, dose-responsive epigenetic alterations have not been routinely considered. Here, we evaluated the utility of microRNA (miRNA) profiling in mouse liver and blood, as well as in mouse primary hepatocytes in vitro, to indicate mechanisms of liver perturbation due to short-term exposure of the known rodent liver hepatotoxicant and carcinogen, furan. Benchmark dose modeling of miRNA measurements (BMDmiR) were compared to the referent transcriptional (BMDT) and apical (BMDA) estimates. These analyses indicate a robust dose response for 34 miRNAs to furan and involvement of p53-linked pathways in furan-mediated hepatotoxicity, supporting mRNA and apical measurements. Liver-sourced miRNAs were also altered in the blood and primary hepatocytes. Overall, these results indicate mechanistic involvement of miRNA in furan carcinogenicity and provide evidence of their potential utility as accessible biomarkers of exposure and disease.

Prognostic biomarkers and molecular pathways mediating Helicobacter pylori–induced gastric cancer: a network-biology approach

Cancer of the stomach is the second most frequent cancer-related death worldwide. The survival rate of patients with gastric cancer (GC) remains fragile. There is a requirement to discover biomarkers for prognosis approaches. Helicobacter pylori in the stomach is closely associated with the progression of GC. We identified the genes associated with poor/favorable prognosis in H. pylori–induced GC. Multivariate statistical analysis was applied on the Gene Expression Omnibus (GEO) dataset GSE54397 to identify differentially expressed miRNAs (DEMs) in gastric tissues with H. pylori–induced cancer compared with the H. pylori–positive with non-cancerous tissue. A protein interaction map (PIM) was built and subjected to DEMs targets. The enriched pathways and biological processes within the PIM were identified based on substantial clusters. Thereafter, the most critical genes in the PIM were illustrated, and their prognostic impact in GC was investigated. Considering p-value less than 0.01 and |Log2 fold change| as >1, five microRNAs demonstrated significant changes among the two groups. Gene functional analysis revealed that the ubiquitination system, neddylation pathway, and ciliary process are primarily involved in H. pylori–induced GC. Survival analysis illustrated that the overexpression of DOCK4, GNAS, CTGF, TGF-b1, ESR1, SELE, TIMP3, SMARCE1, and TXNIP was associated with poor prognosis, while increased MRPS5 expression was related to a favorable prognosis in GC patients. DOCK4, GNAS, CTGF, TGF-b1, ESR1, SELE, TIMP3, SMARCE1, TXNIP, and MRPS5 may be considered prognostic biomarkers for H. pylori–induced GC. However, experimental validation is necessary in the future.

Impact of Environmental and Epigenetic Changes on Mesenchymal Stem Cells during Aging

Many crucial epigenetic changes occur during early skeletal development and throughout life due to aging, disease and are heavily influenced by an individual’s lifestyle. Epigenetics is the study of heritable changes in gene expression as the result of changes in the environment without any mutation in the underlying DNA sequence. The epigenetic profiles of cells are dynamic and mediated by different mechanisms, including histone modifications, non-coding RNA-associated gene silencing and DNA methylation. Given the underlining role of dysfunctional mesenchymal tissues in common age-related skeletal diseases such as osteoporosis and osteoarthritis, investigations into skeletal stem cells or mesenchymal stem cells (MSC) and their functional deregulation during aging has been of great interest and how this is mediated by an evolving epigenetic landscape. The present review describes the recent findings in epigenetic changes of MSCs that effect growth and cell fate determination in the context of aging, diet, exercise and bone-related diseases.

The Role of Epicardial Adipose Tissue-Derived MicroRNAs in the Regulation of Cardiovascular Disease: A Narrative Review

Cardiovascular diseases have been leading cause of death worldwide for many decades, and obesity has been acknowledged as a risk factor for cardiovascular diseases. In the present review, human epicardial adipose tissue-derived miRNAs reported to be differentially expressed under pathologic conditions are discussed and summarized. The results of the literature review indicate that some of the epicardial adipose tissue-derived miRNAs are believed to be cardioprotective, while some others show quite the opposite effects depending on the underlying pathologic conditions. Furthermore, they suggest that that the epicardial adipose tissue-derived miRNAs have great potential as both a diagnostic and therapeutic modality. Nevertheless, mainly due to highly limited availability of human samples, it is very difficult to make any generalized claims on a given miRNA in terms of its overall impact on the cardiovascular system. Therefore, further functional investigation of a given miRNA including, but not limited to, the study of its dose effect, off-target effects, and potential toxicity is required. We hope that this review can provide novel insights to transform our current knowledge on epicardial adipose tissue-derived miRNAs into clinically viable therapeutic strategies for preventing and treating cardiovascular diseases.

Studies on the contribution of PPAR Gamma to tuberculosis physiopathology

Introduction

Tuberculosis (TB) is a major health problem characterized by an immuno-endocrine imbalance: elevated plasma levels of cortisol and pro- and anti-inflammatory mediators, as well as reduced levels of dehydroepiandrosterone. The etiological agent, Mycobacterium tuberculosis (Mtb), is captured by pulmonary macrophages (Mf), whose activation is necessary to cope with the control of Mtb, however, excessive activation of the inflammatory response also leads to tissue damage. Glucocorticoids (GC) are critical elements to counteract the immunoinflammatory reaction, and peroxisome proliferator-activated receptors (PPARs) are also involved in this regard. The primary forms of these receptors are PPARϒ, PPARα, and PPARβ/δ, the former being the most involved in anti-inflammatory responses. In this work, we seek to gain some insight into the contribution of PPARϒ in immuno-endocrine-metabolic interactions by focusing on clinical studies in pulmonary TB patients and in vitro experiments on a Mf cell line.

Methods and results

We found that TB patients, at the time of diagnosis, showed increased expression of the PPARϒ transcript in their peripheral blood mononuclear cells, positively associated with circulating cortisol and related to disease severity. Given this background, we investigated the expression of PPARϒ (RT-qPCR) in radiation-killed Mtb-stimulated human Mf. The Mtb stimulation of Mf derived from the human line THP1 significantly increased the expression of PPARϒ, while the activation of this receptor by a specific agonist decreased the expression of pro- and anti-inflammatory cytokines (IL-1β and IL-10). As expected, the addition of GC to stimulated cultures reduced IL-1β production, while cortisol treatment together with the PPARϒ agonist lowered the levels of this proinflammatory cytokine in stimulated cultures. The addition of RU486, a glucocorticoid receptor antagonist, only reversed the inhibition produced by the addition of GC.

Conclusion

The current results provide a stimulating background for further analysis of the interconnection between PPARs and steroid hormones in the context of Mtb infection.

Association of miR-34a and miR-143 levels with PPARγ gene expression in adipose tissues of non-diabetic adults

BACKGROUND

Peroxisome proliferator-activated receptor gamma (PPARγ) is a promising therapeutic molecule. Epigenetic mechanisms, including non-coding RNAs, regulate the expression level of the PPARγ gene.

OBJECTIVE

We aimed to examine the PPARγ expression in non-diabetic individuals in four body mass index (BMI) categories and its association with miR-34a and miR-143 expression.

METHODS

Visceral and subcutaneous adipose tissues (VAT and SAT) samples were collected from patients undergoing bariatric or elective open abdominal surgeries. The subjects (mean age: 42±14.8 years) included 18 normal-weight, 19 overweight, 18 obese, and 19 morbidly obese individuals. The RNAs levels were determined by quantitative real-time PCR.

RESULTS

The PPARγ expression was significantly upregulated in both adipose depots of the morbidly obese subjects compared to the normal group. SAT PPARγ level was significantly increased in the obese group compared to the normal-weight group (P<0.01); this increase was also significant in the SAT of morbidly obese subjects compared to the overweight cases (P=0.02). Differences in the regulation of PPARγ expression in both SAT and VAT were significant between the four groups (P<0.05). While miR-143 was overexpressed in the SAT of obese and morbidly obese individuals compared to the normal-weight group, the pairwise comparison showed no significant difference in the miR-34a expression of SAT between the four BMI groups (P>0.01). After controlling for the confounding factors, the expression of VAT PPARγ was directly associated with the miR-34a level in the normal-weight group (β=0.311, P=0.010). A negative association was observed between the VAT PPARγ expression and miR-34a expression in obese cases (β = - 0.594, P=0.039).

CONCLUSION

The results also confirmed the regulatory function of microRNAs in the PPARγ expression and adipogenesis.

miR-27b inhibition contributes to cytotoxicity in patulin-exposed HEK293 cells

Patulin (PAT) is a mycotoxin produced by Penicillium and other fungi that contaminate fruit. PAT targets the kidney and is associated with nephrotoxicity. Micro-RNAs (miRNA) may offer new insights into PAT-induced nephrotoxicity. Cytochrome P₄₅₀ family 1, subfamily B, polypeptide 1 (CYP1B1), involved in metabolism of dietary toxins is negatively regulated by miR-27b and linked with the nuclear factor kappa B (NF-κB) pathway and peroxisome proliferator activated receptor gamma (PPARɣ) in renal fibrosis. This study investigated the effects of PAT on miR-27b, CYP1B1, PPARɣ and cytotoxicity in human kidney (HEK293) cells. HEK293 cells were exposed to PAT (2.5 μM, 24h). Protein expression of CYP1B1, PPARɣ, NF-κB (p65), pNF-κB (p65) (phospho-Ser563) and cleaved PARP-1 was quantified using western blotting. QPCR evaluated mRNA levels of CYP1B1, IL-6, miR-27b, OGG1, mtDNA, TFAM and UCP2. Mitochondrial membrane potential and phosphatidylserine (PS) externalization was evaluated by flow cytometry while levels of ATP and caspase -9, -8, -3/7 activity was measured using luminometry. PAT significantly decreased miR-27b levels (p = 0.0014) and increased CYP1B1 mRNA (p = 0.0015) and protein (p = 0.0013) levels. PPARɣ protein expression was significantly increased (p = 0.0002) and associated with decreased NF-κB activation (p = 0.0273) and IL-6 mRNA levels (p = 0.0265). Finally, PAT significantly compromised mitochondrial repair mechanisms and increased apoptotic biomarkers. PAT altered miR-27b levels and PPARɣ, with associated changes to NF-κB activation, downstream IL-6 and CYP1B1 expression. These results show that PAT impairs detoxification mechanisms leading to mitochondrial damage and apoptosis. In conclusion, PAT altered the epigenetic environment and impaired detoxification processes, supporting a mechanism for nephrotoxic outcomes.

Identification of Prognostic Biomarkers in Papillary Thyroid Cancer and Developing Non-Invasive Diagnostic Models Through Integrated Bioinformatics Analysis

BACKGROUND

Papillary thyroid cancer (PTC) is the most frequent subtype of thyroid carcinoma, mainly detected in patients with benign thyroid nodules (BTN). Due to the invasiveness of accurate diagnostic tests, there is a need to discover applicable biomarkers for PTC. So, in this study, we aimed to identify the genes associated with prognosis in PTC. Besides, we performed a machine learning tool to develop a non-invasive diagnostic approach for PTC.

METHODS

For the study purposes, the miRNA dataset GSE130512 was downloaded from the GEO database and then analyzed to identify the common differentially expressed miRNAs in patients with non-metastatic PTC (nm-PTC)/metastatic PTC (m-PTC) compared with BTNs. The SVM was also applied to differentiate patients with PTC from those patients with BTN using the common DEMs. A protein-protein interaction network was also constructed based on the targets of the common DEMs. Next, functional analysis was performed, the hub genes were determined, and survival analysis was then executed.

RESULTS

A total of three common miRNAs were found to be differentially expressed among patients with nm-PTC/m-PTC compared with BTNs. In addition, it was established that the autophagosome maturation, ciliary basal body-plasma membrane docking, antigen processing as ubiquitination & proteasome degradation, and class I MHC mediated antigen processing & presentation are associated with the pathogenesis of PTC. Furthermore, it was illustrated that RPS6KB1, CCNT1, SP1, and CHD4 might serve as new potential biomarkers for PTC prognosis.

CONCLUSION

RPS6KB1, CCNT1, SP1, and CHD4 may be considered new potential biomarkers used for prognostic aims in PTC. However, performing validation tests is inevitable in the future.

Diagnostic value of PPARδ and miRNA-17 expression levels in patients with non-small cell lung cancer

The PPARδ gene codes protein that belongs to the peroxisome proliferator-activated receptor (PPAR) family engaged in a variety of biological processes, including carcinogenesis. Specific biological and clinical roles of PPARδ in non-small cell lung cancer (NSCLC) is not fully explained. The association of PPARα with miRNA regulators (e.g. miRNA-17) has been documented, suggesting the existence of a functional relationship of all PPARs with epigenetic regulation. The aim of the study was to determine the PPARδ and miR-17 expression profiles in NSCLC and to assess their diagnostic value in lung carcinogenesis. PPARδ and miR-17 expressions was assessed by qPCR in NSCLC tissue samples (n = 26) and corresponding macroscopically unchanged lung tissue samples adjacent to the primary lesions served as control (n = 26). PPARδ and miR-17 expression were significantly lower in NSCLC than in the control (p = 0.0001 and p = 0.0178; respectively). A receiver operating characteristic (ROC) curve analysis demonstrated the diagnostic potential in discriminating NSCLC from the control with an area under the curve (AUC) of 0.914 for PPARδ and 0.692 for miR-17. Significant increase in PPARδ expression in the control for current smokers vs. former smokers (p = 0.0200) and increase in miR-17 expression in control tissue adjacent to adenocarcinoma subtype (p = 0.0422) were observed. Overexpression of miR-17 was observed at an early stage of lung carcinogenesis, which may suggest that it acts as a putative oncomiR. PPARδ and miR-17 may be markers differentiating tumour tissue from surgical margin and miR-17 may have diagnostic role in NSCLC histotypes differentiation.

Peroxisome Proliferator-Activated Receptors (PPARs) and Oxidative Stress in Physiological Conditions and in Cancer

Peroxisome proliferator-activated receptors (PPARs) belong to the nuclear hormone receptor superfamily. Originally described as “orphan nuclear receptors”, they can bind both natural and synthetic ligands acting as agonists or antagonists. In humans three subtypes, PPARα, β/δ, γ, are encoded by different genes, show tissue-specific expression patterns, and contribute to the regulation of lipid and carbohydrate metabolisms, of different cell functions, including proliferation, death, differentiation, and of processes, as inflammation, angiogenesis, immune response. The PPAR ability in increasing the expression of various antioxidant genes and decreasing the synthesis of pro-inflammatory mediators, makes them be considered among the most important regulators of the cellular response to oxidative stress conditions. Based on the multiplicity of physiological effects, PPAR involvement in cancer development and progression has attracted great scientific interest with the aim to describe changes occurring in their expression in cancer cells, and to investigate the correlation with some characteristics of cancer phenotype, including increased proliferation, decreased susceptibility to apoptosis, malignancy degree and onset of resistance to anticancer drugs. This review focuses on mechanisms underlying the antioxidant and anti-inflammatory properties of PPARs in physiological conditions, and on the reported beneficial effects of PPAR activation in cancer.

Molecular mechanism of anti-adipogenic effect of vitexin in differentiating hMSCs

In this study, we evaluated a detailed molecular mechanism of anti-adipogenic activity of vitexin, apigenin flavone glucoside, present in germinated fenugreek seeds, in differentiating human mesenchymal stem cells (hMSCs). The lipid content of differentiated adipocytes was estimated by ORO staining. Effect on mitotic clonal expansion was checked by cell cycle analysis. Expression of early and terminal adipocyte differentiation markers, anti- and pro-adipogenic transcription factors and signalling intermediates regulating them was evaluated at RNA and protein level. We found vitexin to be non-cytotoxic up to 20 μM at which intracellular lipid accumulation was significantly decreased. Cell cycle analysis suggested that vitexin does not affect mitotic clonal expansion. Expression of early and late differentiation markers, such as CEBPα, CEBPβ, PPARγ, FABP4, perilipin, adiponectin and Glut4 was significantly reduced in the presence of vitexin. Expression of KLF4 and KLF15, positive regulators of PPARγ, was decreased, whereas that of negative regulators, namely KLF2, GATA2, miR20a, miR27a, miR27b, miR128, miR130a, miR130b, miR182 and miR548 increased with vitexin treatment. This effect was mediated by the activation of the AMP-activated protein kinase (AMPK) pathway via the activation of LepR and additionally by inhibiting ROS. Thus, our results showed that vitexin regulates the expression of PPARγ and inhibits adipogenesis of hMSCs at an early stage of differentiation.

PPARs as Metabolic Sensors and Therapeutic Targets in Liver Diseases

Carbohydrates and lipids are two components of the diet that provide the necessary energy to carry out various physiological processes to help maintain homeostasis in the body. However, when the metabolism of both biomolecules is altered, development of various liver diseases takes place; such as metabolic-associated fatty liver diseases (MAFLD), hepatitis B and C virus infections, alcoholic liver disease (ALD), and in more severe cases, hepatocelular carcinoma (HCC). On the other hand, PPARs are a family of ligand-dependent transcription factors with an important role in the regulation of metabolic processes to hepatic level as well as in other organs. After interaction with specific ligands, PPARs are translocated to the nucleus, undergoing structural changes to regulate gene transcription involved in lipid metabolism, adipogenesis, inflammation and metabolic homeostasis. This review aims to provide updated data about PPARs’ critical role in liver metabolic regulation, and their involvement triggering the genesis of several liver diseases. Information is provided about their molecular characteristics, cell signal pathways, and the main pharmacological therapies that modulate their function, currently engaged in the clinic scenario, or in pharmacological development.

The lipid-lowering drug fenofibrate combined with si-HOTAIR can effectively inhibit the proliferation of gliomas

Background

Fenofibrate is a fibric acid derivative known to have a lipid-lowering effect. Although fenofibrate-induced peroxisome proliferator-activated receptor alpha (PPARα) transcription activation has been shown to play an important role in the malignant progression of gliomas, the underlying mechanisms are poorly understood.

Methods

In this study, we analyzed TCGA database and found that there was a significant negative correlation between the long noncoding RNA (lncRNA) HOTAIR and PPARα. Then, we explored the molecular mechanism by which lncRNA HOTAIR regulates PPARα in cell lines in vitro and in a nude mouse glioma model in vivo and explored the effect of the combined application of HOTAIR knockdown and fenofibrate treatment on glioma invasion.

Results

For the first time, it was shown that after knockdown of the expression of HOTAIR in gliomas, the expression of PPARα was significantly upregulated, and the invasion and proliferation ability of gliomas were obviously inhibited. Then, glioma cells were treated with both the PPARα agonist fenofibrate and si-HOTAIR, and the results showed that the proliferation and invasion of glioma cells were significantly inhibited.

Conclusions

Our results suggest that HOTAIR can negatively regulate the expression of PPARα and that the combination of fenofibrate and si-HOTAIR treatment can significantly inhibit the progression of gliomas. This introduces new ideas for the treatment of gliomas.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08417-z.

SIRT6 transcriptionally regulates fatty acid transport by suppressing PPARγ

Pathological lipid accumulation is often associated with enhanced uptake of free fatty acids via specific transporters in cardiomyocytes. Here, we identify SIRT6 as a critical transcriptional regulator of fatty acid transporters in cardiomyocytes. We find that SIRT6 deficiency enhances the expression of fatty acid transporters, leading to enhanced fatty acid uptake and lipid accumulation. Interestingly, the haploinsufficiency of SIRT6 is sufficient to induce the expression of fatty acid transporters and cause lipid accumulation in murine hearts. Mechanistically, SIRT6 depletion enhances the occupancy of the transcription factor PPARγ on the promoters of critical fatty acid transporters without modulating the acetylation of histone 3 at Lys 9 and Lys 56. Notably, the binding of SIRT6 to the DNA-binding domain of PPARγ is critical for regulating the expression of fatty acid transporters in cardiomyocytes. Our data suggest exploiting SIRT6 as a potential therapeutic target for protecting the heart from metabolic diseases.

MicroRNAs in shaping the resolution phase of inflammation

Inflammation is a host defense mechanism orchestrated through imperative factors - acute inflammatory responses mediated by cellular and molecular events leading to activation of defensive immune subsets - to marginalize detrimental injury, pathogenic agents and infected cells. These potent inflammatory events, if uncontrolled, may cause tissue damage by perturbing homeostasis towards immune dysregulation. A parallel host mechanism operates to contain inflammatory pathways and facilitate tissue regeneration. Thus, resolution of inflammation is an effective moratorium on the pro-inflammatory pathway to avoid the tissue damage inside the host and leads to reestablishment of tissue homeostasis. Dysregulation of the resolution pathway can have a detrimental impact on tissue functionality and contribute to the diseased state. Multiple reports have suggested peculiar dynamics of miRNA expression during various pro- and anti-inflammatory events. The roles of miRNAs in the regulation of immune responses are well-established. However, understanding of miRNA regulation of the resolution phase of events in infection or wound healing models, which is sometimes misconstrued as anti-inflammatory signaling, remains limited. Due to the deterministic role of miRNAs in pro-inflammatory and anti-inflammatory pathways, in this review we have provided a broad perspective on the putative role of miRNAs in the resolution of inflammation and explored their imminent role in therapeutics.

Peroxisome Proliferator-Activated Receptors (PPAR), fatty acids and microRNAs: Implications in women delivering low birth weight babies

Low birth weight (LBW) babies are associated with neonatal morbidity and mortality and are at increased risk for noncommunicable diseases (NCDs) in later life. However, the molecular determinants of LBW are not well understood. Placental insufficiency/dysfunction is the most frequent etiology for fetal growth restriction resulting in LBW and placental epigenetic processes are suggested to be important regulators of pregnancy outcome. Early life exposures like altered maternal nutrition may have long-lasting effects on the health of the offspring via epigenetic mechanisms like DNA methylation and microRNA (miRNA) regulation. miRNAs have been recognized as major regulators of gene expression and are known to play an important role in placental development. Angiogenesis in the placenta is known to be regulated by transcription factor peroxisome proliferator-activated receptor (PPAR) which is activated by ligands such as long-chain-polyunsaturated fatty acids (LCPUFA). In vitro studies in different cell types indicate that fatty acids can influence epigenetic mechanisms like miRNA regulation. We hypothesize that maternal fatty acid status may influence the miRNA regulation of PPAR genes in the placenta in women delivering LBW babies. This review provides an overview of miRNAs and their regulation of PPAR gene in the placenta of women delivering LBW babies.Abbreviations: AA - Arachidonic Acid; Ago2 - Argonaute2; ALA - Alpha-Linolenic Acid; ANGPTL4 - Angiopoietin-Like Protein 4; C14MC - Chromosome 14 miRNA Cluster; C19MC - Chromosome 19 miRNA Cluster; CLA - Conjugated Linoleic Acid; CSE - Cystathionine γ-Lyase; DHA - Docosahexaenoic Acid; EFA - Essential Fatty Acids; E2F3 - E2F transcription factor 3; EPA - Eicosapentaenoic Acid; FGFR1 - Fibroblast Growth Factor Receptor 1; GDM - Gestational Diabetes Mellitus; hADMSCs - Human Adipose Tissue-Derived Mesenchymal Stem Cells; hBMSCs - Human Bone Marrow Mesenchymal Stem Cells; HBV - Hepatitis B Virus; HCC - Hepatocellular Carcinoma; HCPT - Hydroxycamptothecin; HFD - High-Fat Diet; Hmads - Human Multipotent Adipose-Derived Stem; HSCS - Human Hepatic Stellate Cells; IUGR - Intrauterine Growth Restriction; LA - Linoleic Acid; LBW - Low Birth Weight; LCPUFA - Long-Chain Polyunsaturated Fatty Acids; MEK1 - Mitogen-Activated Protein Kinase 1; MiRNA - MicroRNA; mTOR - Mammalian Target of Rapamycin; NCDs - NonCommunicable Diseases; OA - Oleic Acid; PASMC - Pulmonary Artery Smooth Muscle Cell; PLAG1 - Pleiomorphic Adenoma Gene 1; PPAR - Peroxisome Proliferator-Activated Receptor; PPARα - PPAR alpha; PPARγ - PPAR gamma; PPARδ - PPAR delta; pre-miRNA - precursor miRNA; RISC - RNA-Induced Silencing Complex; ROS - Reactive Oxygen Species; SAT - Subcutaneous Adipose Tissue; WHO - World Health Organization.

Non-coding RNA crosstalk with nuclear receptors in liver disease

The dysregulation of nuclear receptors (NRs) underlies the pathogenesis of a variety of liver disorders. Non-coding RNAs (ncRNAs) are defined as RNA molecules transcribed from DNA but not translated into proteins. MicroRNAs (miRNAs) and long non-coding RNAs (lncRNAs) are two types of ncRNAs that have been extensively studied for regulating gene expression during diverse cellular processes. NRs as therapeutic targets in liver disease have been exemplified by the successful application of their pharmacological ligands in clinics. MiRNA-based reagents or drugs are emerging as flagship products in clinical trials. Advancing our understanding of the crosstalk between NRs and ncRNAs is critical to the development of diagnostic and therapeutic strategies. This review summarizes recent findings on the reciprocal regulation between NRs and ncRNAs (mainly on miRNAs and lncRNAs) and their implication in liver pathophysiology, which might be informative to the translational medicine of targeting NRs and ncRNAs in liver disease.

Identifying Potential Biomarkers in Colorectal Cancer and Developing Non-invasive Diagnostic Models Using Bioinformatics Approaches

Background: Colorectal cancer (CRC) is one of the most frequent causes of gastrointestinal tumors. Due to the invasiveness of the current diagnostic methods, there is an urgent need to develop non-invasive diagnostic approaches for CRC. The exact mechanisms and the most important genes associated with the development of CRC are not fully demonstrated. Objectives: This study aimed to identify differentially expressed miRNAs (DEMs), key genes, and their regulators associated with the pathogenesis of CRC. The signaling pathways and biological processes (BPs) that were significantly affected in CRC were also indicated. Moreover, two non-invasive models were constructed for CRC diagnosis. Methods: The miRNA dataset GSE59856 was downloaded from the Gene Expression Omnibus (GEO) database and analyzed to identify DEMs in CRC patients compared with healthy controls (HCs). A protein-protein interaction (PPI) network was built and analyzed. Significant clusters in the PPI networks were identified, and the BPs and pathways associated with these clusters were studied. The hub genes in the PPI network, as well as their regulators were identified. Results: A total of 569 DEMs were demonstrated with the criteria of P value <0.001. A total of 110 essential genes and 30 modules were identified in the PPI network. Functional analysis revealed that 1005 BPs, 9 molecular functions (MFs), 14 cellular components (CCs), and 887 pathways were significantly affected in CRC. A total of 22 transcription factors (TFs) were demonstrated as the regulators of the hubs. Conclusion: Our results may provide new insight into the pathogenesis of CRC and advance the diagnostic and therapeutic methods of the disease. However, confirmation is required in the future.

MicroRNA-21 Contributes to Acute Liver Injury in LPS-Induced Sepsis Mice by Inhibiting PPARα Expression

The severity of sepsis may be associated with excessive inflammation, thus leading to acute liver injury. MicroRNA-21 is highly expressed in the liver of a variety of inflammation-related diseases, and PPARα is also proved to participate in regulating inflammation. In the present study, the LPS-induced sepsis model was established. We found that microRNA-21 expression was upregulated in the liver of sepsis mice, and microRNA-21 inhibition significantly reduced the liver injury. The expression of liver injury markers, inflammation cytokines, and PPARα in the septic mice was higher than in antagomir-21 treated septic mice. In addition, we also found that PPARα is the target gene of microRNA-21; PPARα antagonist GW6471 could reverse the effect of antagomir-21. In conclusion, our study illustrated that microRNA-21 exacerbate acute liver injury in sepsis mice by inhibiting PPARα expression.

Low-dose Bisphenol-A Promotes Epigenetic Changes at Pparγ Promoter in Adipose Precursor Cells

Exposure to endocrine-disrupting chemicals such as Bisphenol-A (BPA) is associated with an increase in obesity prevalence. Diet is the primary cause of human exposure to this contaminant. BPA promotes obesity by inducing adipocyte dysfunction and altering adipogenesis. Contradictory evidence and unanswered questions are reported in the literature concerning the BPA effects on adipogenesis. To clarify this issue, we tested the effects of prolonged low-dose BPA exposure on different phases of adipogenesis in committed 3T3L1 and uncommitted NIH3T3 preadipocytes. Our findings show that BPA effects on the adipogenesis are mediated by epigenetic mechanisms by reducing peroxisome proliferator-activated receptor gamma (Pparγ) promoter methylation in preadipocytes. Nevertheless, in BPA-exposed 3T3L1, Pparγ expression only transiently increases as lipid accumulation at day 4 of differentiation, without altering the adipogenic potential of the precursor cells. In the absence of differentiation mix, BPA does not make the 3T3L1 an in vitro model of spontaneous adipogenesis and the effects on the Pparγ expression are still limited at day 4 of differentiation. Furthermore, BPA exposure does not commit the NIH3T3 to the adipocyte lineage, although Pparγ overexpression is more evident both in preadipocytes and during the adipocyte differentiation. Interestingly, termination of the BPA exposure restores the Pparγ promoter methylation and inflammatory profile of the 3T3L1 cells. This study shows that BPA induces epigenetic changes in a key adipogenic gene. These modifications are reversible and do not affect preadipocyte commitment and/or differentiation. We identify an alternative transcriptional mechanism by which BPA affects gene expression and demonstrate how the challenge of preventing exposure is fundamental for human health.

Plasma Levels of miR-27a, miR-130b, and miR-301a in Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a gynecological endocrine disorder in women of reproductive age. There is adequate evidence that suggests several microRNAs (miRNAs) are of great importance for PCOS. It seems that dysregulated expression of miR-27a, miR-130b, and miR-301a are associated with PCOS. The aim of this study was to investigate whether plasma levels of these miRNAs are different between patients with PCOS and healthy controls. Fifty-three women with a definite diagnosis of PCOS, and 53 healthy controls were enrolled. MiRNAs expression levels in plasma were evaluated by real-time PCR. The diagnostic values of each miRNA were calculated by the receiver operating characteristic (ROC) curve and areas under the curves (AUC). The main clinical characteristics were not significantly different between the two groups. The circulating plasma expression levels of miR-27a and miR-301a had a significant increase (P = 0.0008 and P <0.0001, respectively) but miR-130b expression level decreased in the patient group (P <0.0001). The AUC for miR-27a, miR-130b, and miR-301a were 0.71, 0.77, and 0.66, respectively. A positive exponential was observed for miR-27a and miR-301a in multiple logistic regression. Changes in the plasma expressions of the studied miRNAs are likely to be associated with PCOS phenotypes. MiR-27a has a potential to serve as a diagnostic biomarker of PCOS.

Transcriptional and post-transcriptional regulation of the pregnane X receptor: a rationale for interindividual variability in drug metabolism

The pregnane X receptor (PXR, encoded by the NR1I2 gene) is a ligand-regulated transcription factor originally described as a master regulator of xenobiotic detoxification. Later, however, PXR was also shown to interact with endogenous metabolism and to be further associated with various pathological states. This review focuses predominantly on such aspects, currently less covered in literature, as the control of PXR expression per se in the context of inter-individual differences in drug metabolism. There is growing evidence that non-coding RNAs post-transcriptionally regulate PXR. Effects on PXR have especially been reported for microRNAs (miRNAs), which include miR-148a, miR-18a-5p, miR-140-3p, miR-30c-1-3p and miR-877-5p. Likewise, miRNAs control the expression of both transcription factors involved in PXR expression and regulators of PXR function. The impact of NR1I2 genetic polymorphisms on miRNA-mediated PXR regulation is also discussed. As revealed recently, long non-coding RNAs (lncRNAs) appear to interfere with PXR expression. Reciprocally, PXR activation regulates non-coding RNA expression, thus comprising another level of PXR action in addition to the direct transactivation of protein-coding genes. PXR expression is further controlled by several transcription factors (cross-regulation) giving rise to different PXR transcript variants. Controversies remain regarding the suggested role of feedback regulation (auto-regulation) of PXR expression. In this review, we comprehensively summarize the miRNA-mediated, lncRNA-mediated and transcriptional regulation of PXR expression, and we propose that deciphering the precise mechanisms of PXR expression may bridge our knowledge gap in inter-individual differences in drug metabolism and toxicity.

GW0742 activates miR-17-5p and inhibits TXNIP/NLRP3-mediated inflammation after hypoxic-ischaemic injury in rats and in PC12 cells

This study aimed to investigate the effects of PPAR‐β/δ receptor agonist GW0742 on neuroinflammation in a rat model of hypoxia‐ischaemia (HI) and in PC12 cells in OGD model. HI was induced by ligating the common carotid artery and inducing hypoxia for 150 minutes. Immunofluorescence was used for quantification of microglia activation and for determining cellular localization of PPAR‐β/δ. Expression of proteins was measured by Western blot. Activation of miR‐17‐5p by GW0742 was assessed in PC12 cells by Dual‐Luciferase Reporter Gene Assay. The endogenous expression of TXNIP, NLRP3, cleaved caspase‐1 and IL‐1β was increased after HI. GW0742 treatment significantly reduced the number of activated pro‐inflammatory microglia in ipsilateral hemisphere after HI. Mechanistically, GW0742 significantly decreased the expression of TXNIP, NLRP3, IL‐6 and TNF‐α. Either PPAR‐β/δ antagonist GSK3787, miR‐17‐5p inhibitor, or TXNIP CRISPR activation abolished the anti‐inflammatory effects of GW0742. Activation of PPAR‐β/δ by GW0742 activated miR‐17‐5p expression in PC12 cells and increased cell viability after OGD, which was accompanied by decreased expression of TXNIP and reduced secretion of IL‐1β and TNF‐α. In conclusion, GW0742 may be a promising neurotherapeutic for the management of HI patients.

Reversal of diet-induced hepatic steatosis by peripheral CB1 receptor blockade in mice is p53/miRNA-22/SIRT1/PPARα dependent

OBJECTIVE

The endocannabinoid (eCB) system is increasingly recognized as being crucially important in obesity-related hepatic steatosis. By activating the hepatic cannabinoid-1 receptor (CB₁R), eCBs modulate lipogenesis and fatty acid oxidation. However, the underlying molecular mechanisms are largely unknown.

METHODS

We combined unbiased bioinformatics techniques, mouse genetic manipulations, multiple pharmacological, molecular, and cellular biology approaches, and genomic sequencing to systematically decipher the role of the hepatic CB₁R in modulating fat utilization in the liver and explored the downstream molecular mechanisms.

RESULTS

Using an unbiased normalized phylogenetic profiling analysis, we found that the CB₁R evolutionarily coevolves with peroxisome proliferator-activated receptor-alpha (PPARα), a key regulator of hepatic lipid metabolism. In diet-induced obese (DIO) mice, peripheral CB₁R blockade (using AM6545) induced the reversal of hepatic steatosis and improved liver injury in WT, but not in PPARα^-/- mice. The antisteatotic effect mediated by AM6545 in WT DIO mice was accompanied by increased hepatic expression and activity of PPARα as well as elevated hepatic levels of the PPARα-activating eCB-like molecules oleoylethanolamide and palmitoylethanolamide. Moreover, AM6545 was unable to rescue hepatic steatosis in DIO mice lacking liver sirtuin 1 (SIRT1), an upstream regulator of PPARα. Both of these signaling molecules were modulated by the CB₁R as measured in hepatocytes exposed to lipotoxic conditions or treated with CB₁R agonists in the absence/presence of AM6545. Furthermore, using microRNA transcriptomic profiling, we found that the CB₁R regulated the hepatic expression, acetylation, and transcriptional activity of p53, resulting in the enhanced expression of miR-22, which was found to specifically target SIRT1 and PPARα.

CONCLUSIONS

We provide strong evidence for a functional role of the p53/miR-22/SIRT1/PPARα signaling pathway in potentially mediating the antisteatotic effect of peripherally restricted CB₁R blockade.

Prognostic value of the miRNA-27a and PPAR/RXRα signaling axis in patients with thyroid carcinoma

The authors aimed to evaluate the prognostic value of miRNA-27a (miR-27a), peroxisome proliferator-activated receptor alpha/gamma (PPARα/γ) and retinoid X receptor alpha (RXRα) tissue expression in patients with thyroid carcinoma. The expression levels were quantified in 174 archived thyroid specimens using real-time quantitative PCR. Downregulation of miR-27a was associated with lymph node stage and multifocality. PPARα expression was associated with histopathological type, tumor size and lymph node invasion. Moreover, RXRα expression was lower in patients who underwent total/subtotal thyroidectomy or received radioactive iodine treatment. Patients with upregulated miR-27a and downregulated RXRα showed a higher frequency of advanced lymph node stage and relapse by cluster analysis. Both miR-27a and PPARα/RXRα showed association with different poor prognostic indices in thyroid cancer patients.

Early microRNA indicators of PPARα pathway activation in the liver

MicroRNAs (miRNAs) are short non-coding RNA species that play key roles in post-transcriptional regulation of gene expression. MiRNAs also serve as a promising source of early biomarkers for different environmental exposures and health effects, although there is limited information linking miRNA changes to specific target pathways. In this study, we measured liver miRNAs in male B6C3F1 mice exposed to a known chemical activator of the peroxisome proliferator-activated receptor alpha (PPARα) pathway, di(2-ethylhexyl) phthalate (DEHP), for 7 and 28 days at concentrations of 0, 750, 1500, 3000, or 6000 ppm in feed. At the highest dose tested, DEHP altered 61 miRNAs after 7 days and 171 miRNAs after 28 days of exposure, with 48 overlapping miRNAs between timepoints. Analysis of these 48 common miRNAs indicated enrichment in PPARα–related targets and other pathways related to liver injury and cancer. Four of the 10 miRNAs exhibiting a clear dose trend were linked to the PPARα pathway: mmu-miRs-125a-5p, -182−5p, -20a−5p, and -378a−3p. mmu-miRs-182−5p and -378a−3p were subsequently measured using digital drop PCR across a dose range for DEHP and two related phthalates with weaker PPARα activity, di-n-octyl phthalate and n-butyl benzyl phthalate, following 7-day exposures. Analysis of mmu-miRs-182−5p and -378a−3p by transcriptional benchmark dose analysis correctly identified DEHP as having the greatest potency. However, benchmark dose estimates for DEHP based on these miRNAs (average 163; range 126−202 mg/kg-day) were higher on average than values for PPARα target genes (average 74; range 29−183 mg/kg-day). These findings identify putative miRNA biomarkers of PPARα pathway activity and suggest that early miRNA changes may be used to stratify chemical potency.

The Interplay among miRNAs, Major Cytokines, and Cancer-Related Inflammation

Inflammation is closely related with the progression of cancer and is an indispensable component that orchestrates the tumor microenvironment. Studies suggest that different mediator and cellular effectors, including cytokines (interleukins, tumor necrosis factor-α [TNF-α], transforming growth factor-β [TGF-β], and granulocyte macrophage colony-stimulating factor [GM-CSF]), chemokines, as well as some transcription factors (nuclear factor κB [NF-κB], signal transducer and activator of transcription 3 [STAT3], hypoxia-inducible factor-1α [HIF1α]), play a crucial role during cancer-related inflammation (CRI). MicroRNAs (miRNAs) are the key components of cellular physiology. They play notable roles during posttranscriptional gene regulation and, thus, might have a potential role in controlling the inflammatory cascade during cancer progression. Taking into consideration the role identified for miRNAs in relation to inflammatory cytokines, we have tried to review their participation in neoplastic progression. Additionally, the involvement of miRNAs with some important transcription factors (NF-κB, STAT3, HIF1α) and proteins (cyclooxygenase-2 [COX-2], inducible nitric oxide synthase [iNOS]) closely associated with inflammation during cancer has also been discussed. A clear insight into the responsibility of miRNAs in cytokine signaling and inflammation related to CRI could project them as new therapeutic molecules, which could lead to improved treatment of CRI in the near future.

Role of lycopene in smoke-promoted chronic obstructive pulmonary disease and lung carcinogenesis

Chronic obstructive pulmonary disease (COPD) and lung cancer are a major cause of morbidity and mortality worldwide, with cigarette smoking being the single most important risk factor for both. Emerging evidence indicates alterations in reverse cholesterol transport-mediated removal of excess cholesterol from lung, and intracellular cholesterol overload to be involved in smoke-promoted COPD and lung cancer development. Since there are currently few effective treatments for COPD and lung cancer, it is important to identify food-derived, biologically active compounds, which can protect against COPD and lung cancer development. High intake of the carotenoid lycopene, as one of phytochemicals, is associated with a decreased risk of chronic lung lesions. This review article summarizes and discusses epidemiologic evidence, in vitro and in vivo studies regarding the prevention of smoke-promoted COPD and lung carcinogenesis through dietary lycopene as an effective intervention strategy. We focus on the recent research implying that lycopene preventive effect is through targeting the main genes involved in reverse cholesterol transport. This review also indicates gaps in knowledge about the function of lycopene against COPD and lung cancer, offering directions for further research.

Auxiliary antitumor effects of fungal proteins from Hericium erinaceus by target on the gut microbiota

Cancer represents a major disease burden worldwide. Despite continuous advances obtained in medical therapies recently, resistance to standard drugs and adverse effects still represent important causes of therapeutic failure. There is growing evidence that the gut microbiota can affect the response to chemo- and immunotherapeutic drugs by modulating efficacy and/or toxicity, and diet is the most important factor affecting the gut microbiota. In this study, we assessed the auxiliary antitumor effects of immunomodulatory fungal proteins from Hericium erinaceus (HEP) administered with the chemotherapy drug 5-Fluorouracil (5-Fu), and we attempted to identify new potential prebiotic bacteria for auxiliary antitumor treatment. There were 1,455 proteins identified from H. erinaceus. In a xenografted mouse model of cancer, HEP with 5-Fu significantly suppressed tumor growth, inhibited inflammatory markers such as interferon (IFN)-γ, interleukin (IL)-1β, IL-2, IL-6, tumor necrosis factor (TNF)-α, and lipopolysaccharide (LPS), and regulated the expression of Akt, CCDN1, CKD4, FOXM1, MMP7, MYC, PPAR-α, and PPAR-γ. 16S rRNA sequencing showed that HEP ameliorated the dysbacteriosis induced by 5-Fu, as it inhibited certain aerobic and microaerobic bacteria including Parabacteroides, Flavobacteriaceae, Christensenellaceae, Anoxybacillus, Aggregatibacter, Comamonadaceae, Planococcaceae, Desulfovibrionaceae, Sporosarcina, Staphylococcus, Aerococcaceae, and Bilophila in the xenografted mice, and increase some probiotic bacteria such as Bifidobacterium, Gemellales, Blautia, Sutterella, Anaerostipes, Roseburia, Lachnobacterium, Lactobacillus, and Desulfovibrio. This demonstrates that HEP could promote the antitumor efficacy of 5-Fu by improving the microbiota composition, the immune inflammatory response, and homeostasis.

MicroRNA miR-222 mediates pioglitazone beneficial effects on skeletal muscle of diet-induced obese mice

Pioglitazone belongs to the class of drugs thiazolidinediones (TZDs) and is an oral hypoglycemic drug, used in the treatment of type 2 diabetes, which improves insulin sensitivity in target tissues. Adipose tissue is the main target of pioglitazone, a PPARg and PPARa agonist; however, studies also point to skeletal muscle as a target. Non-PPAR targets of TZDs have been described, thus we aimed to study the direct effects of pioglitazone on skeletal muscle and the possible role of microRNAs as targets of this drug. Pioglitazone treatment of obese mice increased insulin-mediated glucose transport as a result of increased fatty acid oxidation and mitochondrial activity. PPARg blockage by treatment with GW9662 nullified pioglitazone's effect on systemic and muscle insulin sensitivity and citrate synthase activity of obese mice. After eight weeks of high-fat diet, miR-221-3p expression in soleus muscle was similar among the groups and miR-23b-3p and miR-222-3p were up-regulated in obese mice compared to the control group, and treatment with pioglitazone was able to reverse this condition. In vitro studies in C2C12 cells suggest that inhibition of miR-222-3p protects C2C12 cells from insulin resistance and increased non-mitochondrial respiration induced by palmitate. Together, these data demonstrate a role of pioglitazone in the downregulation of microRNAs that is not dependent on PPARg. Moreover, miR-222 may be a novel PPARg-independent mechanism through which pioglitazone improves insulin sensitivity in skeletal muscle.

Inflexibility of the plasma miRNA response following a high-carbohydrate meal in overweight insulin-resistant women

Context

Metabolic inflexibility is a characteristic of insulin resistance, limiting the ability to transiently regulate oxidative metabolism and gene expression in response to nutrient availability. Little is known of the flexibility of post-transcriptional regulation, including circulatory miRNAs (c-miRNAs).

Design

The abundances of targeted c-miRNAs, with reported functions in metabolic regulation, were analysed in response to a high-carbohydrate meal in healthy weight insulin-sensitive (IS) and overweight insulin-resistant (IR) women.

Participants

Age-matched healthy weight IS (n = 20, BMI = 24.3 ± 0.70) and overweight IR (n = 20, BMI = 28.6 ± 0.67) women.

Methods

An abundance of c-miRNAs was quantified prior to and following a high-carbohydrate breakfast meal (2500 kJ; 50% carbohydrate, 20% fat and 27% protein). Target genes of the differentially regulated c-miRNA were measured in RNA extracted from circulatory peripheral blood mononuclear cells (PBMCs).

Results

In healthy weight IS women, both miR-15a-5p (p = 0.03) and miR-17-5p (p < 0.01) levels were halved at 4 h post-meal. These miRNA remained unaltered following the same meal in the overweight IR women. Furthermore, amongst genes targeted by these miRNA, CPT1A (p = 0.01) and IL8 (p = 0.03) had also reduced expression 4 h post-meal only in the healthy weight IS women.

Conclusions

The study findings provide preliminary evidence for a possible extension of metabolic inflexibility to include c-miRNAs.

Trial registration

The clinical trial is registered with Australian New Zealand Clinical Trials Registry under Trial registration: ANZCTR: ACTRN12615001108505. Registered on 21 October 2015.

Hepatic PPARα function and lipid metabolic pathways are dysregulated in polymicrobial sepsis

Despite intensive research and constant medical progress, sepsis remains one of the most urgent unmet medical needs of today. Most studies have been focused on the inflammatory component of the disease; however, recent advances support the notion that sepsis is accompanied by extensive metabolic perturbations. During times of limited caloric intake and high energy needs, the liver acts as the central metabolic hub in which PPARα is crucial to coordinate the breakdown of fatty acids. The role of hepatic PPARα in liver dysfunction during sepsis has hardly been explored. We demonstrate that sepsis leads to a starvation response that is hindered by the rapid decline of hepatic PPARα levels, causing excess free fatty acids, leading to lipotoxicity, and glycerol. In addition, treatment of mice with the PPARα agonist pemafibrate protects against bacterial sepsis by improving hepatic PPARα function, reducing lipotoxicity and tissue damage. Since lipolysis is also increased in sepsis patients and pemafibrate protects after the onset of sepsis, these findings may point toward new therapeutic leads in sepsis.

Resveratrol Reduces Lipid Accumulation through Upregulating the Expression of MicroRNAs Regulating Fatty Acid Bet Oxidation in Liver Cells: Evidence from In-vivo and In-vitro Studies

MicroRNAs have been shown to regulate lipogenesis in liver. The aim of the present study was to investigate whether the effects of resveratrol (RSV) on lipogenesis are associated with the changes in the expression of two miRNAs (miR-107 and miR-10b) that regulate lipogenic pathways. 30 wild type C57BL/6j male mice were randomly fed three diets: a standard chow diet (ND), a high fat diet (HFD, 60% fat) and the high fat diet supplemented with 0.4% RSV (HFD-RSV) for 16 weeks. HepG2 cells were treated with high glucose (33 mM) and RSV (20 µM) for 24 h. The expression of the genes and miRNAs were measured by real-time PCR. Triglyceride level was increased in the liver of mice and HepG2 cells. In both animal and In-vitro experiments, triglyceride level was significantly decreased in groups treated with RSV. The expression of the miR-107 and miR-10b was significantly upregulated in the liver of HFD mice, whereas HFD-RSV group demonstrated a significant lower expression of both miRNAs compared to HFD group. In addition, RSV treatment significantly upregulated the expression of CPT-1a and PPARα genes in the liver of HFD mice. Moreover, treatment with RSV could reduce the expression of miR-107 and miR-10b and increase the expression of CPT-1a and PPARα in HG-treated HepG2 cells. These evidence, as a whole, suggest that RSV could exert its anti-lipogenic effect partially through alterations in the expression of miR-107 and miR-10b in liver cells.

MicroRNA-27a/b-3p and PPARG regulate SCAMP3 through a feed-forward loop during adipogenesis

MicroRNAs (miRNA) modulate gene expression through feed-back and forward loops. Previous studies identified miRNAs that regulate transcription factors, including Peroxisome Proliferator Activated Receptor Gamma (PPARG), in adipocytes, but whether they influence adipogenesis via such regulatory loops remain elusive. Here we predicted and validated a novel feed-forward loop regulating adipogenesis and involved miR-27a/b-3p, PPARG and Secretory Carrier Membrane Protein 3 (SCAMP3). In this loop, expression of both PPARG and SCAMP3 was independently suppressed by miR-27a/b-3p overexpression. Knockdown of PPARG downregulated SCAMP3 expression at the late phase of adipogenesis, whereas reduction of SCAMP3 mRNA levels increased PPARG expression at early phase in differentiation. The latter was accompanied with upregulation of adipocyte-enriched genes, including ADIPOQ and FABP4, suggesting an anti-adipogenic role for SCAMP3. PPARG and SCAMP3 exhibited opposite behaviors regarding correlations with clinical phenotypes, including body mass index, body fat mass, adipocyte size, lipolytic and lipogenic capacity, and secretion of pro-inflammatory cytokines. While adipose PPARG expression was associated with more favorable metabolic phenotypes, SCAMP3 expression was linked to increased fat mass and insulin resistance. Together, we identified a feed-forward loop through which miR-27a/b-3p, PPARG and SCAMP3 cooperatively fine tune the regulation of adipogenesis, which potentially may impact whole body metabolism.

CHIR-99021 regulates mitochondrial remodelling via β-catenin signalling and miRNA expression during endodermal differentiation

Mitochondrial remodelling is a central feature of stem cell differentiation. However, little is known about the regulatory mechanisms during these processes. Previously, we found that a pharmacological inhibitor of glycogen synthase kinase-3α and -3β, CHIR-99021, initiates human adipose stem cell differentiation into human definitive endodermal progenitor cells (hEPCs), which were directed to differentiate synchronously into hepatocyte-like cells after further treatment with combinations of soluble factors. In this study, we show that CHIR-99021 promotes mitochondrial biogenesis, the expression of PGC-1α (also known as PPARGC1A), TFAM and NRF1 (also known as NFE2L1), oxidative phosphorylation capacities, and the production of reactive oxygen species in hEPCs. Blocking mitochondrial dynamics using siRNA targeting DRP1 (also known as DNM1L) impaired definitive endodermal differentiation. Downregulation of β-catenin (CTNNB1) expression weakened the effect of CHIR-99021 on the induction of mitochondrial remodelling and the expression of transcription factors for mitochondrial biogenesis. Moreover, CHIR-99021 decreased the expression of miR-19b-2-5p, miR-23a-3p, miR-23c, miR-130a-3p and miR-130a-5p in hEPCs, which target transcription factors for mitochondrial biogenesis. These data demonstrate that CHIR-99021 plays a role in mitochondrial structure and function remodelling via activation of the β-catenin signalling pathway and inhibits the expression of miRNAs during definitive endodermal differentiation.This article has an associated First Person interview with the first author of the paper.

MicroRNA-29a Attenuates Diabetic Glomerular Injury through Modulating Cannabinoid Receptor 1 Signaling

Diabetic nephropathy often leads to end-stage renal disease and life-threatening morbidities. Simple control of risk factors is insufficient to prevent the progression of diabetic nephropathy, hence the need for discovering new treatments is of paramount importance. Recently, the dysregulation of microRNAs or the cannabinoid signaling pathway has been implicated in the pathogenesis of various renal tubulointerstitial fibrotic damages and thus novel therapeutic targets for chronic kidney diseases have emerged; however, the role of microRNAs or cannabinoid receptors on diabetes-induced glomerular injuries remains to be elucidated. In high-glucose-stressed renal mesangial cells, transfection of a miR-29a precursor sufficiently suppressed the mRNA and protein expressions of cannabinoid type 1 receptor (CB1R). Our data also revealed upregulated CB1R, interleukin-1β, interleukin-6, tumor necrosis factor-α, c-Jun, and type 4 collagen in the glomeruli of streptozotocin (STZ)-induced diabetic mice, whereas the expression of peroxisome proliferator-activated receptor-γ (PPAR-γ) was decreased. Importantly, using gain-of-function transgenic mice, we demonstrated that miR-29a acts as a negative regulator of CB1R, blocks the expressions of these proinflammatory and profibrogenic mediators, and attenuates renal hypertrophy. We also showed that overexpression of miR-29a restored PPAR-γ signaling in the renal glomeruli of diabetic animals. Collectively, our findings indicate that the interaction between miR-29a, CB1R, and PPAR-γ may play an important role in protecting diabetic renal glomeruli from fibrotic injuries.

Role of PPAR-β/δ/miR-17/TXNIP pathway in neuronal apoptosis after neonatal hypoxic-ischemic injury in rats

Activation of peroxisome proliferator-activated receptor beta/delta (PPAR-β/δ), a nuclear receptor acting as a transcription factor, was shown to be protective in various models of neurological diseases. However, there is no information about the role of PPAR-β/δ as well as its molecular mechanisms in neonatal hypoxia-ischemia (HI). In the present study, we hypothesized that PPAR-β/δ agonist GW0742 can activate miR-17-5p, consequently inhibiting TXNIP and ASK1/p38 pathway leading to attenuation of apoptosis. Ten-day-old rat pups were subjected to right common carotid artery ligation followed by 2.5 h hypoxia. GW0742 was administered intranasally 1 and 24 h post HI. PPAR-β/δ receptor antagonist GSK3787 was administered intranasally 1 h before and 24 h after HI, antimir-17-5p and TXNIP CRISPR activation plasmid were administered intracerebroventricularly 24 and 48 h before HI, respectively. Brain infarct area measurement, neurological function tests, western blot, reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR), Fluoro-Jade C and immunofluorescence staining were conducted. GW0742 reduced brain infarct area, brain atrophy, apoptosis, and improved neurological function at 72 h and 4 weeks post HI. Furthermore, GW0742 treatment increased PPAR-β/δ nuclear expression and miR-17-5p level and reduced TXNIP in ipsilateral hemisphere after HI, resulting in inhibition of ASK1/p38 pathway and attenuation of apoptosis. Inhibition of PPAR-β/δ receptor and miR-17-5p and activation of TXNIP reversed the protective effects. For the first time, we provide evidence that intranasal administration of PPAR-β/δ agonist GW0742 attenuated neuronal apoptosis at least in part via PPAR-β/δ/miR-17/TXNIP pathway. GW0742 could represent a therapeutic target for treatment of neonatal hypoxic ischemic encephalopathy (HIE).

Exercise and weight loss interventions and miRNA expression in women with breast cancer

PURPOSE

Obesity and weight gain are associated with comorbidities including a higher risk of tumor recurrence and cancer-related deaths among breast cancer (BC) survivors; however, the underlying mechanisms linking obesity and cancer are poorly understood. Given the lack of clinically validated BC biomarkers, obesity and weight-loss studies utilize serum biomarkers as the intermediary outcomes of tumor recurrence. Studies have indicated microRNAs (miRNA)s are reliable biomarkers for cancer. We hypothesized that miRNA expression correlates with obesity and weight loss amongst BC survivors. This would yield insight into the biological pathways by which this association occurs, enabling more precise development of therapeutics.

PATIENTS AND METHODS

We correlated baseline body mass index (BMI) with serum miRNA expression in 121 BC survivors enrolled in the Hormones and Physical Exercise (HOPE) trial. We then analyzed expression of the 35 most abundant miRNAs from HOPE in a six-month randomized controlled weight-loss trial (Lifestyle, Exercise, and Nutrition; LEAN) in 100 BC survivors. Ingenuity pathway analysis (IPA) software was used to identify biological pathway targets of the BMI-associated and intervention-responsive miRNAs using predictive biomarkers.

RESULTS

Pearson correlations in HOPE identified eight miRNAs associated with BMI, including miR-191-5p (r = - 0.22, p = 0.016) and miR-122-5p (r = 0.25, p = 0.0048). In the LEAN validation study, levels of miR-191-5p significantly increased during the six-month intervention (p = 0.082). Ingenuity Pathway Analysis identified "Estrogen-mediated S-phase entry" (HOPE p = 0.003; LEAN p < 0.001) and "Molecular mechanisms of cancer" (HOPE p = 0.02; LEAN p < 0.001) as the top canonical pathways that significantly correlated with BMI-associated and intervention-responsive miRNAs and contain obesity and cancer-relevant genes including the E2F family of transcription factors and CCND1, which have been implicated in sporadic BC.

CONCLUSION

While the association between obesity and BC recurrence and mortality has been demonstrated in the literature, mechanisms underlying the link between weight gain and cancer are unclear. Using two independent clinical trials, we identified novel miRNAs associative to BMI and weight loss that contribute to the development of cancer. Predictive modeling of miRNA targets identified multiple canonical pathways associated with cancer, highlighting potential mechanisms explaining the link between BMI and increased cancer risk.

Human placental PPAR-γ and SOX-2 expression in serologically proved toxoplasmosis

To explore PPAR-γ and SOX-2 transcription factors expression in placenta according to maternal anti-Toxoplasma gondii serological profile during pregnancy and pregnancy outcome. The study included 240 placentas, grouped according to IgM and IgG serostatus and then subgrouped according to pregnancy outcome that varied between miscarriages, premature labour, stillbirth and giving birth to CNS anomaly or apparently healthy neonates. Samples were H&E stained and histopathologically scored blindly. PPAR-γ expression was measured by ELISA, while SOX-2-positive nuclei were stained immunohistochemically to be calculated by ImageJ. The mean pathological score was significantly higher in IgM+ve and IgG rising than IgG-ve and persistent low groups. Former groups showed significantly higher PPAR-γ (mean = 258.63, 227.11). However, PPAR-γ was higher in apparently healthy neonate subgroups. SOX-2 was significantly lower in IgM+ve and IgG rising groups (mean = 12.87, 43.13) and associated with obvious fibrosis. SOX-2 lowest count was in CNS anomaly subgroup. PPAR-γ and SOX-2 changes may give clues of how Toxoplasma induces pathogenesis during vertical transmission. Triggering PPAR-γ expression may be a tool to downregulate the inflammatory response and establish a metabolically permissive cellular environment for Toxoplasma persistence. Low SOX-2 is suspected to disturb placental mesenchymal stem cells pluripotency and neuroectoderm development.

Fibroblast-like synoviocyte metabolism in the pathogenesis of rheumatoid arthritis

An increasing number of studies show how changes in intracellular metabolic pathways alter tumor and immune cell function. However, little information about metabolic changes in other cell types, including synovial fibroblasts, is available. In rheumatoid arthritis (RA), fibroblast-like synoviocytes (FLS) are the most common cell type at the pannus–cartilage junction and contribute to joint destruction through their production of cytokines, chemokines, and matrix-degrading molecules and by migrating and invading joint cartilage. In this review, we show that these cells differ from healthy synovial fibroblasts, not only in their marker expression, proto-oncogene expression, or their epigenetic changes, but also in their intracellular metabolism. These metabolic changes must occur due to the stressful microenvironment of inflamed tissues, where concentrations of crucial nutrients such as glucose, glutamine, and oxygen are spatially and temporally heterogeneous. In addition, these metabolic changes will increase metabolite exchange between fibroblast and other synovial cells, which can potentially be activated. Glucose and phospholipid metabolism as well as bioactive lipids, including sphingosine-1-phosphate and lysophosphatidic acid, among others, are involved in FLS activation. These metabolic changes likely contribute to FLS involvement in aspects of immune response initiation or abnormal immune responses and strongly contribute to joint destruction.

Changes in the MicroRNA Profile Observed in the Subcutaneous Adipose Tissue of Obese Patients after Laparoscopic Adjustable Gastric Banding

Background. Laparoscopic adjustable gastric banding (LAGB) results in significant lasting weight loss and improved metabolism in obese patients. To evaluate whether epigenetic factors could concur to these benefits, we investigated the subcutaneous adipose tissue (SAT) microRNA (miRNA) profile before (T0) and three years (T1) after LAGB in three morbidly obese women. Case Reports. SAT miRNA profiling, evaluated by TaqMan Array, showed four downexpressed (miR-519d, miR-299-5p, miR-212, and miR-671-3p) and two upexpressed (miR-370 and miR-487a) miRNAs at T1 versus T0. Bioinformatics predicted that these miRNAs regulate genes belonging to pathways associated with the cytoskeleton, inflammation, and metabolism. Western blot analysis showed that PPAR-alpha, which is the target gene of miR-519d, increased after LAGB, thereby suggesting an improvement in SAT lipid metabolism. Accordingly, the number and diameter of adipocytes were significantly higher and lower, respectively, at T1 versus T0. Bioinformatics predicted that the decreased levels of miR-212, miR-299-5p, and miR-671-3p at T1 concur in reducing SAT inflammation. Conclusion. We show that the miRNA profile changes after LAGB. This finding, although obtained in only three cases, suggests that this epigenetic mechanism, by regulating the expression of genes involved in inflammation and lipid metabolism, could concur to improve SAT functionality in postoperative obese patients.