Exposure of neonatal rats to maternal cafeteria feeding during suckling alters hepatic gene expression and DNA methylation in the insulin signalling pathway

Nutrition in early life is a determinant of lifelong physiological and metabolic function. Diseases that are associated with ageing may, therefore, have their antecedents in maternal nutrition during pregnancy and lactation. Rat mothers were fed either a standard laboratory chow diet (C) or a cafeteria diet (O) based upon a varied panel of highly palatable human foods, during lactation. Their offspring were then weaned onto chow or cafeteria diet giving four groups of animals (CC, CO, OC, OO n=9-10). Livers were harvested 10 weeks post-weaning for assessment of gene and protein expression, and DNA methylation. Cafeteria feeding post-weaning impaired glucose tolerance and was associated with sex-specific altered mRNA expression of peroxisome proliferator activated receptor gamma (PPARg) and components of the insulin-signalling pathway (Irs2, Akt1 and IrB). Exposure to the cafeteria diet during the suckling period modified the later response to the dietary challenge. Post-weaning cafeteria feeding only down-regulated IrB when associated with cafeteria feeding during suckling (group OO, interaction of diet in weaning and lactation P=0.041). Responses to cafeteria diet during both phases of the experiment varied between males and females. Global DNA methylation was altered in the liver following cafeteria feeding in the post-weaning period, in males but not females. Methylation of the IrB promoter was increased in group OC, but not OO (P=0.036). The findings of this study add to a growing evidence base that suggests tissue function across the lifespan a product of cumulative modifications to the epigenome and transcriptome, which may be both tissue and sex-specific

A Network of Conserved Damage Survival Pathways Revealed by a Genomic RNAi Screen

Damage initiates a pleiotropic cellular response aimed at cellular survival when appropriate. To identify genes required for damage survival, we used a cell-based RNAi screen against the Drosophila genome and the alkylating agent methyl methanesulphonate (MMS). Similar studies performed in other model organisms report that damage response may involve pleiotropic cellular processes other than the central DNA repair components, yet an intuitive systems level view of the cellular components required for damage survival, their interrelationship, and contextual importance has been lacking. Further, by comparing data from different model organisms, identification of conserved and presumably core survival components should be forthcoming. We identified 307 genes, representing 13 signaling, metabolic, or enzymatic pathways, affecting cellular survival of MMS–induced damage. As expected, the majority of these pathways are involved in DNA repair; however, several pathways with more diverse biological functions were also identified, including the TOR pathway, transcription, translation, proteasome, glutathione synthesis, ATP synthesis, and Notch signaling, and these were equally important in damage survival. Comparison with genomic screen data from Saccharomyces cerevisiae revealed no overlap enrichment of individual genes between the species, but a conservation of the pathways. To demonstrate the functional conservation of pathways, five were tested in Drosophila and mouse cells, with each pathway responding to alkylation damage in both species. Using the protein interactome, a significant level of connectivity was observed between Drosophila MMS survival proteins, suggesting a higher order relationship. This connectivity was dramatically improved by incorporating the components of the 13 identified pathways within the network. Grouping proteins into “pathway nodes” qualitatively improved the interactome organization, revealing a highly organized “MMS survival network.” We conclude that identification of pathways can facilitate comparative biology analysis when direct gene/orthologue comparisons fail. A biologically intuitive, highly interconnected MMS survival network was revealed after we incorporated pathway data in our interactome analysis

hMMS2 serves a redundant role in human PCNA polyubiquitination

<p>Abstract</p> <p>Background</p> <p>In yeast, DNA damage leads to the mono and polyubiquitination of the sliding clamp PCNA. Monoubiquitination of PCNA is controlled by RAD18 (E3 ligase) and RAD6 (E2 conjugating enzyme), while the extension of the monoubiquitinated PCNA into a polyubiquitinated substrate is governed by RAD5, and the heterodimer of UBC13/MMS2. Each modification directs a different branch of the DNA damage tolerance pathway (DDT). While PCNA monoubiquitination leads to error-prone bypass via TLS, biochemical studies have identified MMS2 along with its heteromeric partner UBC13 to govern the error-free repair of DNA lesions by catalyzing the formation of lysine 63-linked polyubiquitin chains (K63-polyUb). Recently, it was shown that PCNA polyubiquitination is conserved in human cells and that this modification is dependent on RAD18, UBC13 and SHPRH. However, the role of hMMS2 in this process was not specifically addressed.</p> <p>Results</p> <p>In this report we show that mammalian cells in which MMS2 was reduced by siRNA-mediated knockdown maintains PCNA polyubiquitination while a knockdown of RAD18 or UBC13 abrogates PCNA ubiquitination. Moreover, the additional knockdown of a UEV1A (MMS2 homolog) does not deplete PCNA polyubiquitination. Finally, mouse embryonic stem cells null for MMS2 with or without the additional depletion of mUEV1A continue to polyubiquitinated PCNA with normal kinetics.</p> <p>Conclusion</p> <p>Our results point to a high level of redundancy in the DDT pathway and suggest the existence of another hMMS2 variant (hMMSv) or complex that can compensate for its loss.</p

Maternal Obesity, Overweight and Gestational Diabetes Affect the Offspring Neurodevelopment at 6 and 18 Months of Age – A Follow Up from the PREOBE Cohort

The study was registered at www.ClinicalTrials.gov, identifier:NCT01634464).Background: Brain development in fetal life and early infancy is critical to determine lifelong performance in various neuropsychological domains. Metabolic pathologies such as overweight, obesity, and gestational diabetes in pregnant women are prevalent and increasing risk factors that may adversely affect long-term brain development in their offspring.Objective: The objective of this research was to investigate the influence of maternal metabolic pathologies on the neurodevelopment of the offspring at 6 and 18 months of life.Design: This was a prospective case-control study of 331 mother- and child pairs from Granada, Spain. The mothers were included during pregnancy into four groups according to their pre-gestational body mass index and their gestational diabetes status; overweight (n:56), obese (n:64), gestational diabetic (n:79), and healthy normal weight controls (n:132). At 6 months and 18 months we assessed the children with the Bayley III scales of neurodevelopment.Results: At 6 months (n=215), we found significant group differences in cognition composite language, and expressive language. Post hoc test revealed unexpectedly higher scores in the obese group compared to the normal weight group and a similar trend in overweight and diabetic group. The effects on language remained significant after adjusting for confounders with an adjusted odds ratio for a value above median in composite language score of 3.3 (95% CI: 1.1, 10.0; p=0.035) for children of obese mothers. At 18 month (n=197), the offspring born to obese mothers had lost five points in language composite scores and the previous differences in language and cognition was replaced by a suggestive trend of lower gross motor scores in the overweight, obese, and diabetic groups.Conclusions: Infants of obese mothers had a temporary accelerated development of cognition and language, followed by a rapid deceleration until 18 months of age, particularly of language scores. This novel observation prompts further confirmative studies to explore possible placental and neurodevelopmental mechanisms involved.This study was funded by Spanish Ministry of Innovation and Science. Junta de Andalucía: Excellence Projects (P06-CTS-02341); Spanish Ministry of Education (Grant no. SB2010-0025); Spanish Ministry of Economy and Competitiveness (BFU2012-40254-C03-01); Further support was received by Abbott Laboratories, Granada, Spain

Epigenetics and allergy: from basic mechanisms to clinical applications

International audienceAllergic diseases are on the rise in the Western world and well-known allergy-protecting and -driving factors such as microbial and dietary exposure, pollution and smoking mediate their influence through alterations of the epigenetic landscape. Here, we review key facts on the involvement of epigenetic modifications in allergic diseases and summarize and critically evaluate the lessons learned from epigenome-wide association studies. We show the potential of epigenetic changes for various clinical applications: as diagnostic tools, to assess tolerance following immunotherapy or possibly predict the success of therapy at an early time point. Furthermore, new technological advances such as epigenome editing and DNAzymes will allow targeted alterations of the epigenome in the future and provide novel therapeutic tools

DNA damage in different Eisenia andrei coelomocytes sub-populations after in vitro exposure to hydrogen peroxide

Earthworms play an essential role in providing soil fertility and may represent an important soil contamination bio-indicator. They are able to ingest soil particles, adsorb substances throughout the intestinal epithelium into the coelomic cavity, where chemicals can come in direct contact with coelomic fluid. Earthworm coelomic fluid shelters leucocytes (coelomocytes) that differ significantly both structurally and functionally. Cellular variability could lead to different susceptibility towards contaminants possibly present in soil ecosystem. In order to define population specific dose response to chemicals and to identify a homogeneous cell population to be used as a relevant biomarker, we investigated different coelomocytes subpopulation, obtained by Percoll density gradient centrifugation (5–35 %), exposed ex vivo to H2O2 in the range of concentration 15–120 µM. DNA damage levels were assessed by the comet assay on unseparated coelomocytes and on three enriched cellular fractions (light, medium and heavy density subpopulations). All tested samples showed a dose–response genotoxic effect following H2O2 exposure. Moreover, light density sub-population appeared more susceptible to oxidative insult highlighted by a significant increase in DNA damage indexes at lower concentrations of H2O2. Present data suggested that in these experimental condition coelomocytes light fraction may represent a more sensitive biomarker of genotoxic insult