Epigenetic Modifications Associated with Maternal Anxiety during Pregnancy and Children's Behavioral Measures.

Epigenetic changes are associated with altered behavior and neuropsychiatric disorders and they modify the trajectory of aging. Maternal anxiety during pregnancy is a common environmental challenge for the fetus, causing changes in DNA methylation. Here, we determined the mediating role of DNA methylation and the moderating role of offspring sex on the association between maternal anxiety and children's behavioral measures. In 83 mother-child dyads, maternal anxiety was assessed in each trimester of pregnancy when the child was four years of age. Children's behavioral measures and children's buccal DNA methylation levels (NR3C1, IGF2/H19 ICR, and LINE1) were examined. Higher maternal anxiety during the third trimester was associated with more methylation levels of the NR3C1. Moderating effects of sex on the association between maternal anxiety and methylation were found for IGF2/H19 and LINE1 CpGs. Mediation analysis showed that methylation of NR3C1 could buffer the effects of maternal anxiety on children's behavioral measures, but this effect did not remain significant after controlling for covariates. In conclusion, our data support an association between maternal anxiety during pregnancy and DNA methylation. The results also underscore the importance of sex differences and timing effects. However, DNA methylation as underlying mechanism of the effect of maternal anxiety during pregnancy on offspring's behavioral measures was not supported.

Increased longevity due to sexual activity in mole-rats is associated with transcriptional changes in the HPA stress axis.

Sexual activity and/or reproduction are associated with a doubling of life expectancy in the long-lived rodent genus Fukomys. To investigate the molecular mechanisms underlying this phenomenon, we analyzed 636 RNA-seq samples across 15 tissues. This analysis suggests that changes in the regulation of the hypothalamic-pituitary-adrenal stress axis play a key role regarding the extended life expectancy of reproductive vs. non-reproductive mole-rats. This is substantiated by a corpus of independent evidence. In accordance with previous studies, the up-regulation of the proteasome and so-called 'anti-aging molecules', for example, dehydroepiandrosterone, is linked with enhanced lifespan. On the other hand, several of our results are not consistent with knowledge about aging of short-lived model organisms. For example, we found the up-regulation of the insulin-like growth factor 1/growth hormone axis and several other anabolic processes to be compatible with a considerable lifespan prolongation. These contradictions question the extent to which findings from short-lived species can be transferred to longer-lived ones.

Correction to: A miRNA catalogue and ncRNA annotation of the short-living fish Nothobranchius furzeri.

Following the publication of this article [1], the authors reported that the images of Figs. 1, 2 and 3 were published in the incorrect order, whereby they mismatch with their captions.

Comment on 'Naked mole-rat mortality rates defy Gompertzian laws by not increasing with age'.

Ruby et al. recently analyzed historical lifespan data on more than 3200 naked mole-rats, collected over a total observation period of about 38 years (Ruby et al., 2018). They report that mortality hazards do not seem to increase across the full range of their so-far-observed lifespan, and conclude that this defiance of Gompertz's law 'uniquely identifies the naked mole-rat as a non-aging mammal'. Here, we explain why we believe this conclusion is premature.

C/EBPß-LIP induces cancer-type metabolic reprogramming by regulating the let-7/LIN28B circuit in mice.

The transcription factors LAP1, LAP2 and LIP are derived from the Cebpb-mRNA through the use of alternative start codons. High LIP expression has been associated with human cancer and increased cancer incidence in mice. However, how LIP contributes to cellular transformation is poorly understood. Here we present that LIP induces aerobic glycolysis and mitochondrial respiration reminiscent of cancer metabolism. We show that LIP-induced metabolic programming is dependent on the RNA-binding protein LIN28B, a translational regulator of glycolytic and mitochondrial enzymes with known oncogenic function. LIP activates LIN28B through repression of the let-7 microRNA family that targets the Lin28b-mRNA. Transgenic mice overexpressing LIP have reduced levels of let-7 and increased LIN28B expression, which is associated with metabolic reprogramming as shown in primary bone marrow cells, and with hyperplasia in the skin. This study establishes LIP as an inducer of cancer-type metabolic reprogramming and as a regulator of the let-7/LIN28B regulatory circuit.

Publisher Correction: Transcriptomic alterations during ageing reflect the shift from cancer to degenerative diseases in the elderly.

The original version of this Article contained an error in the spelling of the author Jule Müller, which was incorrectly given as Julia Müller. Additionally, in Fig. 4a, the blue-red colour scale for fold change in ageing/disease regulation included a blue stripe in place of a red stripe at the right-hand end of the scale. These errors have been corrected in both the PDF and HTML versions of the Article.

Higher gene expression stability during aging in long-lived giant mole-rats than in short-lived rats.

Many aging-associated physiological changes are known to occur in short- and long-lived species with different trajectories. Emerging evidence suggests that numerous life history trait differences between species are based on interspecies variations in gene expression. Little information is available, however, about differences in transcriptome changes during aging between mammals with diverging lifespans. For this reason, we studied the transcriptomes of five tissue types and two age cohorts of two similarly sized rodent species with very different lifespans: laboratory rats (Rattus norvegicus) and giant mole-rats (Fukomys mechowii), with maximum lifespans of 3.8 and more than 20 years, respectively. Our findings show that giant mole-rats exhibit higher gene expression stability during aging than rats. Although well-known aging signatures were detected in all tissue types of rats, they were found in only one tissue type of giant mole-rats. Furthermore, many differentially expressed genes that were found in both species were regulated in opposite directions during aging. This suggests that expression changes which cause aging in short-lived species are counteracted in long-lived species. Taken together, we conclude that expression stability in giant mole rats (and potentially in African mole-rats in general) may be one key factor for their long and healthy life.

3D Network exploration and visualisation for lifespan data.

BACKGROUND: The Ageing Factor Database AgeFactDB contains a large number of lifespan observations for ageing-related factors like genes, chemical compounds, and other factors such as dietary restriction in different organisms. These data provide quantitative information on the effect of ageing factors from genetic interventions or manipulations of lifespan. Analysis strategies beyond common static database queries are highly desirable for the inspection of complex relationships between AgeFactDB data sets. 3D visualisation can be extremely valuable for advanced data exploration. RESULTS: Different types of networks and visualisation strategies are proposed, ranging from basic networks of individual ageing factors for a single species to complex multi-species networks. The augmentation of lifespan observation networks by annotation nodes, like gene ontology terms, is shown to facilitate and speed up data analysis. We developed a new Javascript 3D network viewer JANet that provides the proposed visualisation strategies and has a customised interface for AgeFactDB data. It enables the analysis of gene lists in combination with AgeFactDB data and the interactive visualisation of the results. CONCLUSION: Interactive 3D network visualisation allows to supplement complex database queries by a visually guided exploration process. The JANet interface allows gaining deeper insights into lifespan data patterns not accessible by common database queries alone. These concepts can be utilised in many other research fields.

Species comparison of liver proteomes reveals links to naked mole-rat longevity and human aging.

BACKGROUND: Mammals display a wide range of variation in their lifespan. Investigating the molecular networks that distinguish long- from short-lived species has proven useful to identify determinants of longevity. Here, we compared the livers of young and old long-lived naked mole-rats (NMRs) and the phylogenetically closely related, shorter-lived, guinea pigs using an integrated omics approach. RESULTS: We found that NMR livers display a unique expression pattern of mitochondrial proteins that results in distinct metabolic features of their mitochondria. For instance, we observed a generally reduced respiration rate associated with lower protein levels of respiratory chain components, particularly complex I, and increased capacity to utilize fatty acids. Interestingly, we show that the same molecular networks are affected during aging in both NMRs and humans, supporting a direct link to the extraordinary longevity of both species. Finally, we identified a novel detoxification pathway linked to longevity and validated it experimentally in the nematode Caenorhabditis elegans. CONCLUSIONS: Our work demonstrates the benefits of integrating proteomic and transcriptomic data to perform cross-species comparisons of longevity-associated networks. Using a multispecies approach, we show at the molecular level that livers of NMRs display progressive age-dependent changes that recapitulate typical signatures of aging despite the negligible senescence and extraordinary longevity of these rodents.

Naked mole-rat transcriptome signatures of socially suppressed sexual maturation and links of reproduction to aging.

BACKGROUND: Naked mole-rats (NMRs) are eusocially organized in colonies. Although breeders carry the additional metabolic load of reproduction, they are extremely long-lived and remain fertile throughout their lifespan. This phenomenon contrasts the disposable soma theory of aging stating that organisms can invest their resources either in somatic maintenance, enabling a longer lifespan, or in reproduction, at the cost of longevity. Here, we present a comparative transcriptome analysis of breeders vs. non-breeders of the eusocial, long-lived NMR vs. the polygynous and shorter-lived guinea pig (GP). RESULTS: Comparative transcriptome analysis of tissue samples from ten organs showed, in contrast to GPs, low levels of differentiation between sexes in adult NMR non-breeders. After transition into breeders, NMR transcriptomes are markedly sex-specific, show pronounced feedback signaling via gonadal steroids, and have similarities to reproductive phenotypes in African cichlid fish, which also exhibit social status changes between dominant and subordinate phenotypes. Further, NMRs show functional enrichment of status-related expression differences associated with aging. Lipid metabolism and oxidative phosphorylation-molecular networks known to be linked to aging-were identified among most affected gene sets. Remarkably and in contrast to GPs, transcriptome patterns associated with longevity are reinforced in NMR breeders. CONCLUSION: Our results provide comprehensive and unbiased molecular insights into interspecies differences between NMRs and GPs, both in sexual maturation and in the impact of reproduction on longevity. We present molecular evidence that sexual maturation in NMRs is socially suppressed. In agreement with evolutionary theories of aging in eusocial organisms, we have identified transcriptome patterns in NMR breeders that-in contrast to the disposable soma theory of aging-may slow down aging rates and potentially contribute to their exceptional long life- and healthspan.

Correction: The anti-tumorigenic activity of A2M-A lesson from the naked mole-rat.

[This corrects the article DOI: 10.1371/journal.pone.0189514.].

Long-lived rodents reveal signatures of positive selection in genes associated with lifespan.

The genetics of lifespan determination is poorly understood. Most research has been done on short-lived animals and it is unclear if these insights can be transferred to long-lived mammals like humans. Some African mole-rats (Bathyergidae) have life expectancies that are multiple times higher than similar sized and phylogenetically closely related rodents. To gain new insights into genetic mechanisms determining mammalian lifespans, we obtained genomic and transcriptomic data from 17 rodent species and scanned eleven evolutionary branches associated with the evolution of enhanced longevity for positively selected genes (PSGs). Indicating relevance for aging, the set of 250 identified PSGs showed in liver of long-lived naked mole-rats and short-lived rats an expression pattern that fits the antagonistic pleiotropy theory of aging. Moreover, we found the PSGs to be enriched for genes known to be related to aging. Among these enrichments were "cellular respiration" and "metal ion homeostasis", as well as functional terms associated with processes regulated by the mTOR pathway: translation, autophagy and inflammation. Remarkably, among PSGs are RHEB, a regulator of mTOR, and IGF1, both central components of aging-relevant pathways, as well as genes yet unknown to be aging-associated but representing convincing functional candidates, e.g. RHEBL1, AMHR2, PSMG1 and AGER. Exemplary protein homology modeling suggests functional consequences for amino acid changes under positive selection. Therefore, we conclude that our results provide a meaningful resource for follow-up studies to mechanistically link identified genes and amino acids under positive selection to aging and lifespan determination.

Impairing L-Threonine Catabolism Promotes Healthspan through Methylglyoxal-Mediated Proteohormesis.

Whether and how regulation of genes and pathways contributes to physiological aging is topic of intense scientific debate. By performing an RNA expression-based screen for genes downregulated during aging of three different species, we identified glycine-C-acetyltransferase (GCAT, EC 2.3.1.29). Impairing gcat expression promotes the lifespan of C. elegans by interfering with threonine catabolism to promote methylglyoxal (MGO; CAS 78-98-8) formation in an amine oxidase-dependent manner. MGO is a reactive dicarbonyl inducing diabetic complications in mammals by causing oxidative stress and damaging cellular components, including proteins. While high concentrations of MGO consistently exert toxicity in nematodes, we unexpectedly find that low-dose MGO promotes lifespan, resembling key mediators of gcat impairment. These were executed by the ubiquitin-proteasome system, namely PBS-3 and RPN-6.1 subunits, regulated by the stress-responsive transcriptional regulators SKN-1/NRF2 and HSF-1. Taken together, GCAT acts as an evolutionary conserved aging-related gene by orchestrating an unexpected nonlinear impact of proteotoxic MGO on longevity.

Transcriptomic alterations during ageing reflect the shift from cancer to degenerative diseases in the elderly.

Disease epidemiology during ageing shows a transition from cancer to degenerative chronic disorders as dominant contributors to mortality in the old. Nevertheless, it has remained unclear to what extent molecular signatures of ageing reflect this phenomenon. Here we report on the identification of a conserved transcriptomic signature of ageing based on gene expression data from four vertebrate species across four tissues. We find that ageing-associated transcriptomic changes follow trajectories similar to the transcriptional alterations observed in degenerative ageing diseases but are in opposite direction to the transcriptomic alterations observed in cancer. We confirm the existence of a similar antagonism on the genomic level, where a majority of shared risk alleles which increase the risk of cancer decrease the risk of chronic degenerative disorders and vice versa. These results reveal a fundamental trade-off between cancer and degenerative ageing diseases that sheds light on the pronounced shift in their epidemiology during ageing.

The Definition of Open Reading Frame Revisited.

The term open reading frame (ORF) is of central importance to gene finding. Surprisingly, at least three definitions are in use. We discuss several molecular biological and bioinformatics aspects, and we recommend using the definition in which an ORF is bounded by stop codons.

Haplotypes composed of minor frequency single nucleotide polymorphisms of the TNF gene protect from progression into sepsis: A study using the new sepsis classification.

OBJECTIVES: Several articles have provided conflicting results regarding the role of single nucleotide polymorphisms (SNPs) in the promoter region of the TNF gene in susceptibility to sepsis. Former articles have been based on previous definitions of sepsis. This study investigated the influence of TNF haplotypes on the development of sepsis using the new Sepsis-3 definitions. METHODS: DNA was isolated from patients suffering from infection and systemic inflammatory response syndrome. Haplotyping was performed for six SNPs of TNF. The serum levels of tumour necrosis factor alpha (TNF-α) of these patients were measured using an enzyme immunosorbent assay. Patients were classified into infection and sepsis categories using the Sepsis-3 definitions. Associations between the TNF haplotypes and the clinical characteristics and serum TNF-α levels of the patients were examined. RESULTS: The most common TNF haplotype h1 was composed of major alleles of the studied SNPs. Carriage of haplotypes composed of minor frequency alleles was associated with a lower risk of developing sepsis (odds ratio 0.41, 95% confidence interval 0.19-0.88, p=0.022), but this did not affect the 28-day outcome. Serum TNF-α levels were significantly higher among patients homozygous for h1 haplotypes who developed sepsis compared to infection (p=0.032); a similar result was not observed for patients carrying other haplotypes. CONCLUSIONS: Haplotypes containing minor frequency SNP alleles of TNF protect against the development of sepsis without affecting the outcome.

The pseudogenes of barley.

Pseudogenes have a reputation of being 'evolutionary relics' or 'junk DNA'. While they are well characterized in mammals, studies in more complex plant genomes have so far been hampered by the absence of reference genome sequences. Barley is one of the economically most important cereals and has a genome size of 5.1 Gb. With the first high-quality genome reference assembly available for a Triticeae crop, we conducted a whole-genome assessment of pseudogenes on the barley genome. We identified, characterized and classified 89 440 gene fragments and pseudogenes scattered along the chromosomes, with occasional hotspots and higher densities at the chromosome ends. Full-length pseudogenes (11 015) have preferentially retained their exon-intron structure. Retrotransposition of processed mRNAs only plays a marginal role in their creation. However, the distribution of retroposed pseudogenes reflects the Rabl configuration of barley chromosomes and thus hints at founding mechanisms. While parent genes related to the defense-response were found to be under-represented in cultivated barley, we detected several defense-related pseudogenes in wild barley accessions. The percentage of transcriptionally active pseudogenes is 7.2%, and these may potentially adopt new regulatory roles.The barley genome is rich in pseudogenes and small gene fragments mainly located towards chromosome tips or as tandemly repeated units. Our results indicate non-random duplication and pseudogenization preferences and improve our understanding of the dynamics of gene birth and death in large plant genomes and the mechanisms that lead to evolutionary innovations.

The anti-tumorigenic activity of A2M-A lesson from the naked mole-rat.

Cancer resistance is a major cause for longevity of the naked mole-rat. Recent liver transcriptome analysis in this animal compared to wild-derived mice revealed higher expression of alpha2-macroglobulin (A2M) and cell adhesion molecules, which contribute to the naked mole-rat's cancer resistance. Notably, A2M is known to dramatically decrease with age in humans. We hypothesize that this might facilitate tumour development. Here we found that A2M modulates tumour cell adhesion, migration and growth by inhibition of tumour promoting signalling pathways, e.g. PI3K / AKT, SMAD and up-regulated PTEN via down-regulation of miR-21, in vitro and in tumour xenografts. A2M increases the expression of CD29 and CD44 but did not evoke EMT. Transcriptome analysis of A2M-treated tumour cells, xenografts and mouse liver demonstrated a multifaceted regulation of tumour promoting signalling pathways indicating a less tumorigenic environment mediated by A2M. By virtue of these multiple actions the naturally occurring A2M has strong potential as a novel therapeutic agent.

Tissue-, sex-, and age-specific DNA methylation of rat glucocorticoid receptor gene promoter and insulin-like growth factor 2 imprinting control region.

Tissue-, sex-, and age-specific epigenetic modifications such as DNA methylation are largely unknown. Changes in DNA methylation of the glucocorticoid receptor gene (NR3C1) and imprinting control region (ICR) of IGF2 and H19 genes during the lifespan are particularly interesting since these genes are susceptible to epigenetic modifications by prenatal stress or malnutrition. They are important regulators of development and aging. Methylation changes of NR3C1 affect glucocorticoid receptor expression, which is associated with stress sensitivity and stress-related diseases predominantly occurring during aging. Methylation changes of IGF2/H19 affect growth trajectory and nutrient use with risk of metabolic syndrome. Using a locus-specific approach, we characterized DNA methylation patterns of different Nr3c1 promoters and Igf2/H19 ICR in seven tissues of rats at 3, 9, and 24 mo of age. We found a complex pattern of locus-, tissue-, sex-, and age-specific DNA methylation. Tissue-specific methylation was most prominent at the shores of the Nr3c1 CpG island (CGI). Sex-specific differences in methylation peaked at 9 mo. During aging, Nr3c1 predominantly displayed hypomethylation mainly in females and at shores, whereas hypermethylation occurred within the CGI. Igf2/H19 ICR exhibited age-related hypomethylation occurring mainly in males. Methylation patterns of Nr3c1 in the skin correlated with those in the cortex, hippocampus, and hypothalamus. Skin may serve as proxy for methylation changes in central parts of the hypothalamic-pituitary-adrenal axis and hence for vulnerability to stress- and age-associated diseases. Thus, we provide in-depth insight into the complex DNA methylation changes of rat Nr3c1 and Igf2/H19 during aging that are tissue and sex specific.