Chromatin organization drives the search mechanism of nuclear factors.

Nuclear factors rapidly scan the genome for their targets, but the role of nuclear organization in such search is uncharted. Here we analyzed how multiple factors explore chromatin, combining live-cell single-molecule tracking with multifocal structured illumination of DNA density. We find that factors displaying higher bound fractions sample DNA-dense regions more exhaustively. Focusing on the tumor-suppressor p53, we demonstrate that it searches for targets by alternating between rapid diffusion in the interchromatin compartment and compact sampling of chromatin dense regions. Efficient targeting requires balanced interactions with chromatin: fusing p53 with an exogenous intrinsically disordered region potentiates p53-mediated target gene activation at low concentrations, but leads to condensates at higher levels, derailing its search and downregulating transcription. Our findings highlight the role of disordered regions on factors search and showcase a powerful method to generate traffic maps of the eukaryotic nucleus to dissect how its organization guides nuclear factors action.

Myelomonocytic cells in giant cell arteritis activate trained immunity programs sustaining inflammation and cytokine production.

OBJECTIVE: Trained immunity (TI) is a de facto memory program of innate immune cells, characterized by immunometabolic and epigenetic changes sustaining enhanced production of cytokines. TI evolved as a protective mechanism against infections; however, inappropriate activation can cause detrimental inflammation and might be implicated in the pathogenesis of chronic inflammatory diseases. In this study, we investigated the role of TI in the pathogenesis of giant cell arteritis (GCA), a large-vessel vasculitis characterized by aberrant macrophage activation and excess cytokine production. METHODS: Monocytes from GCA patients and from age- and sex-matched healthy donors were subjected to polyfunctional studies, including cytokine production assays at baseline and following stimulation, intracellular metabolomics, chromatin immunoprecipitation-qPCR, and combined ATAC/RNA sequencing. Immunometabolic activation (i.e. glycolysis) was assessed in inflamed vessels of GCA patients with FDG-PET and immunohistochemistry (IHC), and the role of this pathway in sustaining cytokine production was confirmed with selective pharmacologic inhibition in GCA monocytes. RESULTS: GCA monocytes exhibited hallmark molecular features of TI. Specifically, these included enhanced IL-6 production upon stimulation, typical immunometabolic changes (e.g. increased glycolysis and glutaminolysis) and epigenetic changes promoting enhanced transcription of genes governing pro-inflammatory activation. Immunometabolic changes of TI (i.e. glycolysis) were a feature of myelomonocytic cells in GCA lesions and were required for enhanced cytokine production. CONCLUSIONS: Myelomonocytic cells in GCA activate TI programs sustaining enhanced inflammatory activation with excess cytokine production.

Integrated Multiomic Profiling Identifies the Epigenetic Regulator PRC2 as a Therapeutic Target to Counteract Leukemia Immune Escape and Relapse.

Immune escape represents a major driver of acute myeloid leukemia (AML) reemergence after allogeneic hematopoietic cell transplantation (allo-HCT), with up to 40% of relapses prompted by nongenomic loss of HLA class II expression in leukemia cells. By integrative analysis of gene expression, DNA methylation, and chromatin accessibility in paired diagnosis/relapse primary samples and in the respective patient-derived xenografts (PDX), we identify the polycomb repressive complex 2 (PRC2) as a key epigenetic driver of this immune escape modality. We report that loss of expression of HLA class II molecules is accompanied by a PRC2-dependent reduction in chromatin accessibility. Pharmacologic inhibition of PRC2 subunits rescues HLA class II expression in AML relapses in vitro and in vivo, with consequent recovery of leukemia recognition by CD4+ T cells. Our results uncover a novel link between epigenetics and leukemia immune escape, which may rapidly translate into innovative strategies to cure or prevent AML posttransplantation relapse. SIGNIFICANCE: Loss of HLA class II expression represents a frequent mechanism of leukemia posttransplantation relapse. Here we identify PRC2 as the main epigenetic driver of this immune escape modality and show that its chemical inhibition can reinstate a proficient graft-versus-leukemia effect, providing an innovative rationale for personalized epigenetic immunotherapies. See related commentary by Köhler and Zeiser, p. 1410. This article is highlighted in the In This Issue feature, p. 1397.

Focal adhesion kinase inhibitor TAE226 combined with Sorafenib slows down hepatocellular carcinoma by multiple epigenetic effects.

BACKGROUND: Hepatocellular carcinoma (HCC) is one of the most common and lethal malignant tumours worldwide. Sorafenib (SOR) is one of the most effective single-drug systemic therapy against advanced HCC, but the identification of novel combination regimens for a continued improvement in overall survival is a big challenge. Recent studies highlighted the crucial role of focal adhesion kinase (FAK) in HCC growth. The aim of this study was to investigate the antitumor effects of three different FAK inhibitors (FAKi), alone or in combination with SOR, using in vitro and in vivo models of HCC. METHODS: The effect of PND1186, PF431396, TAE226 on cell viability was compared to SOR. Among them TAE226, emerging as the most effective FAKi, was tested alone or in combination with SOR using 2D/3D human HCC cell line cultures and HCC xenograft murine models. The mechanisms of action were assessed by gene/protein expression and imaging approaches, combined with high-throughput methods. RESULTS: TAE226 was the more effective FAKi to be combined with SOR against HCC. Combined TAE226 and SOR treatment reduced HCC growth both in vitro and in vivo by affecting tumour-promoting gene expression and inducing epigenetic changes via dysregulation of FAK nuclear interactome. We characterized a novel nuclear functional interaction between FAK and the NuRD complex. TAE226-mediated FAK depletion and SOR-promoted MAPK down-modulation caused a decrease in the nuclear amount of HDAC1/2 and a consequent increase of the histone H3 lysine 27 acetylation, thus counteracting histone H3 lysine 27 trimethylation. CONCLUSIONS: Altogether, our findings provide the first evidence that TAE226 combined with SOR efficiently reduces HCC growth in vitro and in vivo. Also, our data highlight that deep analysis of FAK nuclear interactome may lead to the identification of new promising targets for HCC therapy.

Oncogene-induced maladaptive activation of trained immunity in the pathogenesis and treatment of Erdheim-Chester disease.

Trained immunity (TI) is a proinflammatory program induced in monocyte/macrophages upon sensing of specific pathogens and is characterized by immunometabolic and epigenetic changes that enhance cytokine production. Maladaptive activation of TI (ie, in the absence of infection) may result in detrimental inflammation and development of disease; however, the exact role and extent of inappropriate activation of TI in the pathogenesis of human diseases is undetermined. In this study, we uncovered the oncogene-induced, maladaptive induction of TI in the pathogenesis of a human inflammatory myeloid neoplasm (Erdheim-Chester disease, [ECD]), characterized by the BRAFV600E oncogenic mutation in monocyte/macrophages and excess cytokine production. Mechanistically, myeloid cells expressing BRAFV600E exhibit all molecular features of TI: activation of the AKT/mammalian target of rapamycin signaling axis; increased glycolysis, glutaminolysis, and cholesterol synthesis; epigenetic changes on promoters of genes encoding cytokines; and enhanced cytokine production leading to hyperinflammatory responses. In patients with ECD, effective therapeutic strategies combat this maladaptive TI phenotype; in addition, pharmacologic inhibition of immunometabolic changes underlying TI (ie, glycolysis) effectively dampens cytokine production by myeloid cells. This study revealed the deleterious potential of inappropriate activation of TI in the pathogenesis of human inflammatory myeloid neoplasms and the opportunity for inhibition of TI in conditions characterized by maladaptive myeloid-driven inflammation.

The needle and the haystack: single molecule tracking to probe the transcription factor search in eukaryotes.

Transcription factors (TFs) regulate transcription of their target genes by identifying and binding to regulatory regions of the genome among billions of potential non-specific decoy sites, a task that is often presented as a 'needle in the haystack' challenge. The TF search process is now well understood in bacteria, but its characterization in eukaryotes needs to account for the complex organization of the nuclear environment. Here we review how live-cell single molecule tracking is starting to shed light on the TF search mechanism in the eukaryotic cell and we outline the future challenges to tackle in order to understand how nuclear organization modulates the TF search process in physiological and pathological conditions.

Human iPSC-based neurodevelopmental models of globoid cell leukodystrophy uncover patient- and cell type-specific disease phenotypes.

Globoid cell leukodystrophy (GLD) is a rare neurodegenerative lysosomal storage disease caused by an inherited deficiency of ß-galactocerebrosidase (GALC). GLD pathogenesis and therapeutic correction have been poorly studied in patient neural cells. Here, we investigated the impact of GALC deficiency and lentiviral vector-mediated GALC rescue/overexpression in induced pluripotent stem cell (iPSC)-derived neural progenitors and neuronal/glial progeny obtained from two GLD patients. GLD neural progeny displayed progressive psychosine storage, oligodendroglial and neuronal defects, unbalanced lipid composition, and early activation of cellular senescence, depending on the disease-causing mutation. The partial rescue of the neural differentiation program upon GALC reconstitution and psychosine clearance suggests multiple mechanisms contributing to neural pathology in GLD. Also, the pathological phenotype associated to supraphysiological GALC levels highlights the need of regulated GALC expression for proper human neural commitment/differentiation. These data have important implications for establishing safe therapeutic strategies to enhance disease correction of GLD.

Epigenetic Therapies for Acute Myeloid Leukemia and Their Immune-Related Effects.

Over the past decades, our molecular understanding of acute myeloid leukemia (AML) pathogenesis dramatically increased, thanks also to the advent of next-generation sequencing (NGS) technologies. Many of these findings, however, have not yet translated into new prognostic markers or rationales for treatments. We now know that AML is a highly heterogeneous disease characterized by a very low mutational burden. Interestingly, the few mutations identified mainly reside in epigenetic regulators, which shape and define leukemic cell identity. In the light of these discoveries and given the increasing number of drugs targeting epigenetic regulators in clinical development and testing, great interest is emerging for the use of small molecules targeting leukemia epigenome. Together with their effects on leukemia cell-intrinsic properties, such as proliferation and survival, epigenetic drugs may affect the way leukemic cells communicate with the surrounding components of the tumor and immune microenvironment. Here, we review current knowledge on alterations in the AML epigenetic landscape and discuss the promises of epigenetic therapies for AML treatment. Finally, we summarize emerging molecular studies elucidating how epigenetic rewiring in cancer cells may as well exert immune-modulatory functions, boost the immune system, and potentially contribute to better patient outcomes.

An early-senescence state in aged mesenchymal stromal cells contributes to hematopoietic stem and progenitor cell clonogenic impairment through the activation of a pro-inflammatory program.

Hematopoietic stem and progenitor cells (HSPC) reside in the bone marrow (BM) niche and serve as a reservoir for mature blood cells throughout life. Aging in the BM is characterized by low-grade chronic inflammation that could contribute to the reduced functionality of aged HSPC. Mesenchymal stromal cells (MSC) in the BM support HSPC self-renewal. However, changes in MSC function with age and the crosstalk between MSC and HSPC remain understudied. Here, we conducted an extensive characterization of senescence features in BM-derived MSC from young and aged healthy donors. Aged MSC displayed an enlarged senescent-like morphology, a delayed clonogenic potential and reduced proliferation ability when compared to younger counterparts. Of note, the observed proliferation delay was associated with increased levels of SA-ß-galactosidase (SA-ß-Gal) and lipofuscin in aged MSC at early passages and a modest but consistent accumulation of physical DNA damage and DNA damage response (DDR) activation. Consistent with the establishment of a senescence-like state in aged MSC, we detected an increase in pro-inflammatory senescence-associated secretory phenotype (SASP) factors, both at the transcript and protein levels. Conversely, the immunomodulatory properties of aged MSC were significantly reduced. Importantly, exposure of young HSPC to factors secreted by aged MSC induced pro-inflammatory genes in HSPC and impaired HSPC clonogenic potential in a SASP-dependent manner. Altogether, our results reveal that BM-derived MSC from aged healthy donors display features of senescence and that, during aging, MSC-associated secretomes contribute to activate an inflammatory transcriptional program in HSPC that may ultimately impair their functionality.

Focal adhesion kinase depletion reduces human hepatocellular carcinoma growth by repressing enhancer of zeste homolog 2.

Hepatocellular carcinoma (HCC) is the most common type of liver cancer in humans. The focal adhesion tyrosine kinase (FAK) is often over-expressed in human HCC and FAK inhibition may reduce HCC cell invasiveness. However, the anti-oncogenic effect of FAK knockdown in HCC cells remains to be clarified. We found that FAK depletion in HCC cells reduced in vitro and in vivo tumorigenicity, by inducing G2/M arrest and apoptosis, decreasing anchorage-independent growth, and modulating the expression of several cancer-related genes. Among these genes, we showed that FAK silencing decreased transcription and nuclear localization of enhancer of zeste homolog 2 (EZH2) and its tri-methylation activity on lysine 27 of histone H3 (H3K27me3). Accordingly, FAK, EZH2 and H3K27me3 were concomitantly upregulated in human HCCs compared to non-tumor livers. In vitro experiments demonstrated that FAK affected EZH2 expression and function by modulating, at least in part, p53 and E2F2/3 transcriptional activity. Moreover, FAK silencing downregulated both EZH2 binding and histone H3K27me3 levels at the promoter of its target gene NOTCH2. Finally, we found that pharmacological inhibition of FAK activity resembled these effects although milder. In summary, we demonstrate that FAK depletion reduces HCC cell growth by affecting cancer-promoting genes including the pro-oncogene EZH2. Furthermore, we unveil a novel unprecedented FAK/EZH2 crosstalk in HCC cells, thus identifying a targetable network paving the way for new anticancer therapies.

Focal Adhesion Kinase: Insight into Molecular Roles and Functions in Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related death worldwide. Due to the high incidence of post-operative recurrence after current treatments, the identification of new and more effective drugs is required. In previous years, new targetable genes/pathways involved in HCC pathogenesis have been discovered through the help of high-throughput sequencing technologies. Mutations in TP53 and ß-catenin genes are the most frequent aberrations in HCC. However, approaches able to reverse the effect of these mutations might be unpredictable. In fact, if the reactivation of proteins, such as p53 in tumours, holds great promise as anticancer therapy, there are studies arguing that chronic activation of these types of molecules may be deleterious. Thus, recently the efforts on potential targets have focused on actionable mutations, such as those occurring in the gene encoding for focal adhesion kinase (FAK). This tyrosine kinase, localized to cellular focal contacts, is over-expressed in a variety of human tumours, including HCC. Moreover, several lines of evidence demonstrated that FAK depletion or inhibition impair in vitro and in vivo HCC growth and metastasis. Here, we provide an overview of FAK expression and activity in the context of tumour biology, discussing the current evidence of its connection with HCC development and progression.

Gut microbiota profiling of pediatric nonalcoholic fatty liver disease and obese patients unveiled by an integrated meta-omics-based approach.

There is evidence that nonalcoholic fatty liver disease (NAFLD) is affected by gut microbiota. Therefore, we investigated its modifications in pediatric NAFLD patients using targeted metagenomics and metabolomics. Stools were collected from 61 consecutive patients diagnosed with nonalcoholic fatty liver (NAFL), nonalcoholic steatohepatitis (NASH), or obesity and 54 healthy controls (CTRLs), matched in a case-control fashion. Operational taxonomic units were pyrosequenced targeting 16S ribosomal RNA and volatile organic compounds determined by solid-phase microextraction gas chromatography-mass spectrometry. The α-diversity was highest in CTRLs, followed by obese, NASH, and NAFL patients; and ß-diversity distinguished between patients and CTRLs but not NAFL and NASH. Compared to CTRLs, in NAFLD patients Actinobacteria were significantly increased and Bacteroidetes reduced. There were no significant differences among the NAFL, NASH, and obese groups. Overall NAFLD patients had increased levels of Bradyrhizobium, Anaerococcus, Peptoniphilus, Propionibacterium acnes, Dorea, and Ruminococcus and reduced proportions of Oscillospira and Rikenellaceae compared to CTRLs. After reducing metagenomics and metabolomics data dimensionality, multivariate analyses indicated a decrease of Oscillospira in NAFL and NASH groups and increases of Ruminococcus, Blautia, and Dorea in NASH patients compared to CTRLs. Of the 292 volatile organic compounds, 26 were up-regulated and 2 down-regulated in NAFLD patients. Multivariate analyses found that combination of Oscillospira, Rickenellaceae, Parabacteroides, Bacteroides fragilis, Sutterella, Lachnospiraceae, 4-methyl-2-pentanone, 1-butanol, and 2-butanone could discriminate NAFLD patients from CTRLs. Univariate analyses found significantly lower levels of Oscillospira and higher levels of 1-pentanol and 2-butanone in NAFL patients compared to CTRLs. In NASH, lower levels of Oscillospira were associated with higher abundance of Dorea and Ruminococcus and higher levels of 2-butanone and 4-methyl-2-pentanone compared to CTRLs. CONCLUSION: An Oscillospira decrease coupled to a 2-butanone up-regulation and increases in Ruminococcus and Dorea were identified as gut microbiota signatures of NAFL onset and NAFL-NASH progression, respectively. (Hepatology 2017;65:451-464).

High concentrations of H2O2 trigger hypertrophic cascade and phosphatase and tensin homologue (PTEN) glutathionylation in H9c2 cardiomyocytes.

Cardiac hypertrophy occurs in response to different stimuli and is mainly characterized by an enlargement of cardiomyocyte size. During hypertrophy, cardiomyocytes undergo not only radical changes of the cellular architecture but also activation of signaling cascades that counteract the atrophy genes. Experimental studies highlighted that chronic low concentrations of H2O2, induce a hypertrophic phenotype, while higher levels of H2O2 promote apoptosis. In this study, we explored the early and long-term hypertrophic effects of high concentrations of H2O2 on H9c2 rat cardiomyocytes. We found that 2-h stimulation with 200µM H2O2 caused an early dramatic reduction of cell viability, accompanied, 5-days later, by increased cell size and up-regulation of atrial natriuretic peptide transcription. This hypertrophic phenotype is associated to increased Akt phosphorylation and a consequent reduction of the FOXO3a and atrogin-1 gene expression. Moreover, we observed that H2O2 caused the overexpression of miR-212/miR-132 cluster concomitantly to a down-regulation of PTEN transcript without changes in its protein expression. Noteworthy, we found that the treatment of cardiomyocytes with H2O2 further led to an increase of oxidized glutathione and glutathionylation of proteins, including PTEN. In conclusion, our results permit to reconstruct the molecular cascade triggering the cardiomyocyte hypertrophy upon high concentrations of H2O2.

LPS-induced TNF-α factor mediates pro-inflammatory and pro-fibrogenic pattern in non-alcoholic fatty liver disease.

Lipopolysaccharide (LPS) is currently considered one of the major players in non-alcoholic fatty liver disease (NAFLD) pathogenesis and progression. Here, we aim to investigate the possible role of LPS-induced TNF-α factor (LITAF) in inducing a pro-inflammatory and pro-fibrogenic phenotype of non-alcoholic steatohepatitis (NASH).We found that children with NAFLD displayed, in different liver-resident cells, an increased expression of LITAF which correlated with histological traits of hepatic inflammation and fibrosis. Total and nuclear LITAF expression increased in mouse and human hepatic stellate cells (HSCs). Moreover, LPS induced LITAF-dependent transcription of IL-1ß, IL-6 and TNF-α in the clonal myofibroblastic HSC LX-2 cell line, and this effect was hampered by LITAF silencing. We showed, for the first time in HSCs, that LITAF recruitment to these cytokine promoters is LPS dependent. However, preventing LITAF nuclear translocation by p38MAPK inhibitor, the expression of IL-6 and TNF-α was significantly reduced with the aid of p65NF-ĸB, while IL-1ß transcription exclusively required LITAF expression/activity. Finally, IL-1ß levels in plasma mirrored those in the liver and correlated with LPS levels and LITAF-positive HSCs in children with NASH.In conclusion, a more severe histological profile in paediatric NAFLD is associated with LITAF over-expression in HSCs, which in turn correlates with hepatic and circulating IL-1ß levels outlining a panel of potential biomarkers of NASH-related liver damage. The in vitro study highlights the role of LITAF as a key regulator of the LPS-induced pro-inflammatory pattern in HSCs and suggests p38MAPK inhibitors as a possible therapeutic approach against hepatic inflammation in NASH.

MicroRNAs as controlled systems and controllers in non-alcoholic fatty liver disease.

Non-alcoholic fatty liver disease (NAFLD) is a multi-faceted condition including simple steatosis alone or associated with inflammation and ballooning (non-alcoholic steatohepatitis) and eventually fibrosis. The NAFLD incidence has increased over the last twenty years becoming the most frequent chronic liver disease in industrialized countries. Obesity, visceral adiposity, insulin resistance, and many other disorders that characterize metabolic syndrome are the major predisposing risk factors for NAFLD. Furthermore, different factors, including genetic background, epigenetic mechanisms and environmental factors, such as diet and physical exercise, contribute to NAFLD development and progression. Several lines of evidence demonstrate that specific microRNAs expression profiles are strongly associated with several pathological conditions including NAFLD. In NAFLD, microRNA deregulation in response to intrinsic genetic or epigenetic factors or environmental factors contributes to metabolic dysfunction. In this review we focused on microRNAs role both as controlled and controllers molecules in NAFLD development and/or their eventual value as non-invasive biomarkers of disease.

Influence of dietary pattern, physical activity, and I148M PNPLA3 on steatosis severity in at-risk adolescents.

Evidence relating dietary patterns to obesity and related disorders such as non-alcoholic fatty liver disease (NAFLD) is limited in pediatric age. Aim of this study was to analyze the association between dietary patterns, obesity and development of severe steatosis and the metabolic syndrome in a series of children and adolescents referred for suspected NAFLD, and the interaction with the rs738409 I148M PNPLA3 polymorphism. Two hundred patients (112 females) had completed a food frequency and demographic questionnaire. Nearly 58 % were obese, and 32 % were overweight. Mild, moderate, and severe fatty liver was present in 60 (30 %), 87 (44 %), and 51 (26 %) participants, respectively. A great proportion of overweight/obese children and adolescents reported a correct dietary pattern. At multivariate ordinal regression analysis considering demographic, anthropometric, genetic, and behavioral determinants, the major determinant of steatosis severity was PNPLA3 I148M genotype (p < 0.0001), followed by older age (p = 0.017), higher waist circumference (p = 0.016), and less time spent practising physical exercise (p = 0.034). Furthermore, there was a significant interaction between PNPLA3 I148M and intake of sweetened beverages (p = 0.033) and of vegetables (p = 0.038). In conclusion, although dietary pattern was reportedly correct in at-risk overweight adolescents with NAFLD, we report a novel interaction between PNPLA3 I148M and dietary components with the severity of steatosis.

Meta-omic platforms to assist in the understanding of NAFLD gut microbiota alterations: tools and applications.

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease worldwide as a result of the increasing prevalence of obesity, starting from early life stages. It is characterized by a spectrum of liver diseases ranging from simple fatty liver (NAFL) to steatohepatitis (NASH), with a possible progression to fibrosis, thus increasing liver-related morbidity and mortality. NAFLD development is driven by the co-action of several risk factors, including obesity and metabolic syndrome, which may be both genetically induced and diet-related. Recently, particular attention has been paid to the gut-liver axis, which may play a physio-pathological role in the onset and progression of the disease. The gut microbiota is intended to act as a bioreactor that can guarantee autonomous metabolic and immunological functions and that can drive functional strategies within the environment of the body in response to external stimuli. The complexity of the gut microbiota suggests that it behaves as an organ. Therefore, the concept of the gut-liver axis must be complemented with the gut-microbiota-liver network due to the high intricacy of the microbiota components and metabolic activities; these activities form the active diet-driven power plant of the host. Such complexity can only be revealed using systems biology, which can integrate clinical phenomics and gut microbiota data.

EZH2 down-regulation exacerbates lipid accumulation and inflammation in in vitro and in vivo NAFLD.

Non-alcoholic fatty liver disease (NAFLD) is one of the most prevalent, chronic liver diseases, worldwide. It is a multifactorial disease caused by complex interactions between genetic, epigenetic and environmental factors. Recently, several microRNAs, some of which epigenetically regulated, have been found to be up- and/or down-regulated during NAFLD development. However, in NAFLD, the essential role of the Polycomb Group protein Enhancer of Zeste Homolog 2 (EZH2), which controls the epigenetic silencing of specific genes and/or microRNAs by trimethylating Lys27 on histone H3, still remains unknown. In this study, we demonstrate that the nuclear expression/activity of the EZH2 protein is down-regulated both in livers from NAFLD rats and in the free fatty acid-treated HepG2. The drop in EZH2 is inversely correlated with: (i) lipid accumulation; (ii) the expression of pro-inflammatory markers including TNF-α and TGF-ß; and (iii) the expression of miR-200b and miR-155. Consistently, the pharmacological inhibition of EZH2 by 3-Deazaneplanocin A (DZNep) significantly reduces EZH2 expression/activity, while it increases lipid accumulation, inflammatory molecules and microRNAs. In conclusion, the results of this study suggest that the defective activity of EZH2 can enhance the NAFLD development by favouring steatosis and the de-repression of the inflammatory genes and that of specific microRNAs.

Dual role of microRNAs in NAFLD.

MicroRNAs are important post-transcriptional regulators in different pathophysiological processes. They typically affect the mRNA stability or translation finally leading to the repression of target gene expression. Notably, it is thought that microRNAs are crucial for regulating gene expression during metabolic-related disorders, such as nonalcoholic fatty liver disease (NAFLD). Several studies identify specific microRNA expression profiles associated to different histological features of NAFLD, both in animal models and in patients. Therefore, specific assortments of certain microRNAs could have enormous diagnostic potentiality. In addition, microRNAs have also emerged as possible therapeutic targets for the treatment of NAFLD-related liver damage. In this review, we discuss the experimental evidence about microRNAs both as potential non-invasive early diagnostic markers and as novel therapeutic targets in NAFLD and its more severe liver complications.