During myogenic differentiation the short mitochondria of myoblasts change into the extensively elongated network observed in myotubes. The functional relevance and the molecular mechanisms driving the formation of this mitochondrial network are unknown. We now show that mitochondrial elongation is required for myogenesis to occur and that this event depends on the cellular generation of nitric oxide (NO). Inhibition of NO synthesis in myogenic precursor cells leads to inhibition of mitochondrial elongation and of myogenic differentiation. This is due to the enhanced activity, translocation and docking of the pro-fission GTPase dynamin-related protein-1 (Drp1) to mitochondria, leading also to a latent mitochondrial dysfunction that increased sensitivity to apoptotic stimuli. These effects of NO inhibition were not observed in myogenic precursor cells containing a dominant-negative form of Drp1. Both NO-dependent repression of Drp1 action and maintenance of mitochondrial integrity and function were mediated through the soluble guanylate cyclase. These data uncover a novel level of regulation of differentiation linking mitochondrial morphology and function to myogenic differentiation.

In this study we applied a new analytical strategy to investigate the relations between stochastic epigenetic mutations (SEMs) and aging. We analysed methylation levels through the Infinium HumanMethylation27 and HumanMethylation450 BeadChips in a population of 178 subjects ranging from 3 to 106 years. For each CpG probe, epimutated subjects were identified as the extreme outliers with methylation level exceeding three times interquartile ranges the first quartile (Q1-(3 × IQR)) or the third quartile (Q3+(3 × IQR)). We demonstrated that the number of SEMs was low in childhood and increased exponentially during aging. Using the HUMARA method, skewing of X chromosome inactivation (XCI) was evaluated in heterozygotes women. Multivariate analysis indicated a significant correlation between log(SEMs) and degree of XCI skewing after adjustment for age (β = 0.41; confidence interval: 0.14, 0.68; p-value = 0.0053). The PATH analysis tested the complete model containing the variables: skewing of XCI, age, log(SEMs) and overall CpG methylation. After adjusting for the number of epimutations we failed to confirm the well reported correlation between skewing of XCI and aging. This evidence might suggest that the known correlation between XCI skewing and aging could not be a direct association but mediated by the number of SEMs.

Hepatocellular carcinoma (HCC) results from accumulation of both genetic and epigenetic alterations. We investigated the genome-wide DNA methylation profile in 69 pairs of HCC and adjacent non-cancerous liver tissues using the Infinium HumanMethylation 450K BeadChip array. An innovative analytical approach has been adopted to identify Stochastic Epigenetic Mutations (SEMs) in HCC.HCC and peritumoral tissues showed a different epigenetic profile, mainly characterized by loss of DNA methylation in HCC. Total number of SEMs was significantly higher in HCC tumor (median: 77,370) than in peritumoral (median: 5,656) tissues and correlated with tumor grade. A significant positive association emerged between SEMs measured in peritumoral tissue and hepatitis B and/or C virus infection status. A restricted number of SEMs resulted to be shared by more than 90% of HCC tumor samples and never present in peritumoral tissue. This analysis allowed the identification of four epigenetically regulated candidate genes (AJAP1, ADARB2, PTPRN2, SDK1), potentially involved in the pathogenesis of HCC.In conclusion, HCC showed a methylation profile completely deregulated and very far from adjacent non-cancerous liver tissues. The SEM analysis provided valuable clues for further investigations in understanding the process of tumorigenesis in HCC.

BackgroundWerner syndrome is a progeroid disorder characterized by premature age-related phenotypes. Although it is well established that autosomal recessive mutations in the WRN gene is responsible for Werner syndrome, the molecular alterations that lead to disease phenotype remain still unidentified.ResultsTo address whether epigenetic changes can be associated with Werner syndrome phenotype, we analysed genome-wide DNA methylation profile using the Infinium MethylationEPIC BeadChip in the whole blood from three patients affected by Werner syndrome compared with three age- and sex-matched healthy controls. Hypermethylated probes were enriched in glycosphingolipid biosynthesis, FoxO signalling and insulin signalling pathways, while hypomethylated probes were enriched in PI3K-Akt signalling and focal adhesion pathways. Twenty-two out of 47 of the differentially methylated genes belonging to the enriched pathways resulted differentially expressed in a publicly available dataset on Werner syndrome fibroblasts. Interestingly, differentially methylated regions identified CERS1 and CERS3, two members of the ceramide synthase family. Moreover, we found differentially methylated probes within ITGA9 and ADAM12 genes, whose methylation is altered in systemic sclerosis, and within the PRDM8 gene, whose methylation is affected in dyskeratosis congenita and Down syndrome.ConclusionsDNA methylation changes in the peripheral blood from Werner syndrome patients provide new insight in the pathogenesis of the disease, highlighting in some cases a functional correlation of gene expression and methylation status.Electronic supplementary materialThe online version of this article (doi:10.1186/s13148-017-0389-4) contains supplementary material, which is available to authorized users.

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Adult morbid obesity is defined as abnormal or excessive fat accumulation, mostly resulting from a long-term unhealthy lifestyle. Between 10% and 30% of people with obesity exhibit low cardiometabolic risk. The metabolic syndrome has been suggested as an indicator of obesity-related metabolic dysregulation. Although the prevalence of obesity does not seem to be sex-related and metabolic syndrome occurs at all ages, in the last few years, sex-specific differences in the pathophysiology, diagnosis, and treatment of metabolic syndrome have received attention. The aim of this study was to determine the prevalence of metabolic syndrome and its components in different sex and age groups in people with metabolic unhealthy obesity and to compare them with people with metabolic healthy obesity. We analyzed the metabolome in 1350 well-phenotyped morbidly obese individuals and showed that there is a strong sex-dependent association of metabolic syndrome with circulating metabolites. Importantly, we demonstrated that metabolic dysregulation in women and men with severe obesity and metabolic syndrome is age-dependent. The metabolic profiles from our study showed age-dependent sex differences in the impact of MetS which are consistent with the cardiometabolic characterization. Although there is common ground for MetS in the metabolome of severe obesity, men older than 54 are affected in a more extensive and intensive manner. These findings strongly argue for more studies aimed at unraveling the mechanisms that underlie this sex-specific metabolic dysregulation in severe obesity. Moreover, these findings suggest that women and men might benefit from differential sex and age specific interventions to prevent the adverse cardiometabolic effects of severe obesity.

Objective:Metabolomics, which is the latest state-of-the-art omics platform, provides identification and quantitation of all metabolites in a sample, known as the cellular end products of metabolic reactions. These reactions could be a key factor in the development of surrounding complications involved in cardiometabolic disease (CMD). This disease includes a cluster of cardiometabolic risk factors such as obesity, hypertension, fatty liver disease, type 2 diabetes and cardiovascular disease. Therefore, the study of the metabolism involved at the first stages of development of CMD and identification of potential early biomarkers could be essential in patient management.The objective is to identify early potential CMD biomarkers with a metabolomic approach based on nuclear magnetic resonance (NMR) in non-invasive biological samples.Design and method:Male and female Wistar rats, 16 weeks old, were fed with a high-fat and sucrose diet (HFD) for 12 weeks to induce CMD. Blood serum, urine and fecal samples from high-fat fed rats were analyzed by NMR-Metabolomics.Results:HFD induced some evidence of the development of CMD in the clinical data. The alterations included an increase in body weight and arterial blood pressure, changes in glycemic and triglycerides levels and lower HDL levels in the HFD group in comparison with control rats. Moreover, liver histology revealed lipid content, suggesting early hepatic damage. In addition, the metabolomic profile showed metabolism differences in the HFD group that affected metabolites involved in different metabolic pathways including host-microbiota co-metabolites. This analysis seems to indicate a correlation between some microbial metabolites with cardiometabolic parameters.Conclusions:Gut-Microbiota co-metabolism seems to be involved in the first stages of development of CMD on the host organism and the metabolomics can provide early potential biomarkers in a non-invasive way for sub-clinical CMD detection by NMR.

Objective:Metabolic syndrome (MetS) is the principal pathological consequence of obesity. Metabolome dysfunctions lead to multi-organ failure and cardiovascular complications, especially in the elderly. The metabolome is the output of genes-environment interaction and the epigenetic modifications act as their linker. So, it is reasonable a possible interplay between metabolomics and epigenetics. MetS prevalence increases sharply with age, especially in women, reaching in postmenopause a comparable prevalence to men of the same age. Our preliminary metabolomics results suggest stable significant differences between sexes in the global metabolic profiles. So, the aim is to study the interactions between metabolome and epigenome in subjects over 54 years old presenting metabolically healthy obesity (MHO) or severe MetS (MetS.5) to obtain a pathophysiological characterization of the most fragile patients.Design and method:96 subjects (48 cases MetS.5, 48 controls MHO; age 55–85) were selected from a cohort of 1350 adult subjects with extreme obesity (BMI> 40 kg/m2). MetS.5 indicated the presence of the 5 metabolic alterations according to the International Diabetes Federation (IDF) (2005). The cohort was extensively characterized for anthropometric and clinical outlines and NMR metabolomics profiles were previously measured. Global methylation levels were measured in serum using the Infinium MethylationEPIC BeadChip kit and specific statistical analyses were developed.Results:The global methylation levels between cases and controls didn’t appear different, although the epigenetic drift appeared higher in controls, due to the presence on average of a greater number of stochastic epigenetic variations (SEVs). The biological age, reflected by epigenetic age, appeared to be higher, on average, in men over women of similar chronological age, regardless of the pathological state, even if the last worsened the outcome.Conclusions:The epigenetics results, joint to the metabolomic data, may supply innovative knowledge and specific biomarkers involved in physiological mechanisms in healthy obesity and its pathological condition MetS. The results of the present study could add information and introduce new targets and biomarkers for better clinical treatment, a reduction in the risk of mortality and a better quality of life of extreme MetS patients.