scholarly journals Epigenetic clock and methylation studies in elephants

2020 ◽  
Author(s):  
Natalia A. Prado ◽  
Janine L. Brown ◽  
Joseph A. Zoller ◽  
Amin Haghani ◽  
Mingjia Yao ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Association Studies ◽  
Mammalian Species ◽  
Epigenetic Clock ◽  
African Elephants ◽  
Asian Elephants ◽  
Age Related ◽  
Elephant Conservation ◽  
Organismal Development ◽  
Polycomb Repressive Complexes

ABSTRACTAge-associated DNA-methylation profiles have been used successfully to develop highly accurate biomarkers of age (“epigenetic clocks”) in humans, mice, dogs, and other species. Here we present epigenetic clocks for African and Asian elephants. These clocks were developed using novel DNA methylation profiles of 140 elephant blood samples of known age, at loci that are highly conserved between mammalian species, using a custom Infinium array (HorvathMammalMethylChip40). We present epigenetic clocks for Asian elephants (Elephas maximus), African elephants (Loxodonta africana), and both elephant species combined. Two additional human-elephant clocks were constructed by combing human and elephant samples. Epigenome-wide association studies identified elephant age-related CpGs and their proximal genes. The products of these genes play important roles in cellular differentiation, organismal development, metabolism, and circadian rhythms. Intracellular events observed to change with age included the methylation of bivalent chromatin domains, targets of polycomb repressive complexes, and TFAP2C binding sites. These readily available epigenetic clocks can be used for elephant conservation efforts where accurate estimates of age are needed to predict demographic trends.

scholarly journals DNA methylation differs extensively between strains of the same geographical origin and changes with age in Daphnia magna

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Jack Hearn ◽  
Fiona Plenderleith ◽  
Tom J. Little
Keyword(s):  
Dna Methylation ◽  
Caloric Restriction ◽  
Daphnia Magna ◽  
Single Gene ◽  
Methylation Status ◽  
Strain Differences ◽  
Life History Trait ◽  
Food Level ◽  
Epigenetic Clock ◽  
Age Related

Abstract Background Patterns of methylation influence lifespan, but methylation and lifespan may also depend on diet, or differ between genotypes. Prior to this study, interactions between diet and genotype have not been explored together to determine their influence on methylation. The invertebrate Daphnia magna is an excellent choice for testing the epigenetic response to the environment: parthenogenetic offspring are identical to their siblings (making for powerful genetic comparisons), they are relatively short lived and have well-characterised inter-strain life-history trait differences. We performed a survival analysis in response to caloric restriction and then undertook a 47-replicate experiment testing the DNA methylation response to ageing and caloric restriction of two strains of D. magna. Results Methylated cytosines (CpGs) were most prevalent in exons two to five of gene bodies. One strain exhibited a significantly increased lifespan in response to caloric restriction, but there was no effect of food-level CpG methylation status. Inter-strain differences dominated the methylation experiment with over 15,000 differently methylated CpGs. One gene, Me31b, was hypermethylated extensively in one strain and is a key regulator of embryonic expression. Sixty-one CpGs were differentially methylated between young and old individuals, including multiple CpGs within the histone H3 gene, which were hypermethylated in old individuals. Across all age-related CpGs, we identified a set that are highly correlated with chronological age. Conclusions Methylated cytosines are concentrated in early exons of gene sequences indicative of a directed, non-random, process despite the low overall DNA methylation percentage in this species. We identify no effect of caloric restriction on DNA methylation, contrary to our previous results, and established impacts of caloric restriction on phenotype and gene expression. We propose our approach here is more robust in invertebrates given genome-wide CpG distributions. For both strain and ageing, a single gene emerges as differentially methylated that for each factor could have widespread phenotypic effects. Our data showed the potential for an epigenetic clock at a subset of age positions, which is exciting but requires confirmation.

scholarly journals Pair bonding slows epigenetic aging and alters methylation in brains of prairie voles

2020 ◽  
Author(s):  
Lindsay L. Sailer ◽  
Amin Haghani ◽  
Joseph A. Zoller ◽  
Caesar Z. Li ◽  
Alexander G. Ophir ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Brain Tissue ◽  
Association Studies ◽  
Chronological Age ◽  
Epigenetic Clock ◽  
Pair Bonding ◽  
Prairie Voles ◽  
Relative Age ◽  
Biomarkers Of Aging ◽  
Epigenetic Aging

ABSTRACTThe quality of romantic relationships can be predictive of health consequences related to aging. DNA methylation-based biomarkers of aging have been developed for humans and many other mammals and could be used to assess how pair bonding impacts aging. Prairie voles (Microtus ochrogaster) have emerged as a model to study social attachment among adult pairs. Here we describe DNA methylation-based estimators of age for prairie voles based on novel DNA methylation data generated on highly conserved mammalian CpGs measured with a custom array. The multi-tissue epigenetic clock for voles was trained on 3 tissue sources (ear, liver, and samples of brain tissue from within the pair bonding circuit). A novel dual species human-vole clock accurately measured relative age defined as the ratio of chronological age to maximum age. According to the human-vole clock of relative age, sexually inexperienced voles exhibit accelerated epigenetic aging in brain tissue (p = 0.02) when compared to pair bonded animals of the same chronological age. Epigenome wide association studies identified CpGs in four genes that were strongly associated with pair bonding across the three tissue types (brain, ear, and liver): Hnrnph1, Fancl, Fam13b, and Fzd1. Further, four CpGs (near the Bmp4 exon, Eif4g2 3 prime UTR, Robo1 exon, and Nfat5 intron) exhibited a convergent methylation change between pair bonding and aging. This study describes highly accurate DNA methylation-based estimators of age in prairie voles and provides evidence that pair bonding status modulates the methylome.

scholarly journals Novel Epigenetic Clock for Fetal Brain Development Predicts Fetal Epigenetic Age for iPSCs and iPSC-Derived Neurons.

2020 ◽  
Author(s):  
Leonard C Steg ◽  
Gemma L Shireby ◽  
Jennifer Imm ◽  
Jonathan P Davies ◽  
Robert Flynn ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Brain Development ◽  
Fetal Brain ◽  
Cell Types ◽  
Biological Research ◽  
Epigenetic Clock ◽  
Cellular Model ◽  
Neuronal Precursor Cells ◽  
Age Related ◽  
Epigenetic Age

Abstract Induced pluripotent stem cells (iPSCs) and their differentiated neurons (iPSC-neurons) are a widely used cellular model in the research of the central nervous system. However, it is unknown how well they capture age-associated processes, particularly given that pluripotent cells are only present during the early stages of mammalian development. Epigenetic clocks utilize coordinated age-associated changes in DNA methylation to make predictions that correlate strongly with chronological age, and is has been shown that the induction of pluripotency rejuvenates predicted epigenetic age. As existing clocks are not optimized for the study of brain development, to investigate more precisely the epigenetic age of iPSCs and iPSC-neurons, here, we establish the fetal brain clock (FBC), a bespoke epigenetic clock trained in prenatal neurodevelopmental samples. Our data show that the FBC outperforms other established epigenetic clocks in predicting the age of fetal brain samples. We then applied the FBC to DNA methylation data of cellular datasets that have profiled iPSCs and iPSC-derived neuronal precursor cells and neurons and find that these cell types are characterized by a fetal epigenetic age. Furthermore, while differentiation from iPSCs to neurons significantly increases the epigenetic age, iPSC-neurons are still predicted as having fetal epigenetic age. Together our findings reiterate the need for better understanding of the limitations of existing epigenetic clocks for answering biological research questions and highlight a potential limitation of iPSC-neurons as a cellular model for the research of age-related diseases as they might not fully recapitulate an aged phenotype.

scholarly journals Novel epigenetic clock for fetal brain development predicts fetal epigenetic age for iPSCs and iPSC-derived neurons

2020 ◽  
Author(s):  
Leonard C. Steg ◽  
Gemma L. Shireby ◽  
Jennifer Imm ◽  
Jonathan P. Davies ◽  
Robert Flynn ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Brain Development ◽  
Fetal Brain ◽  
Cell Types ◽  
Biological Research ◽  
Epigenetic Clock ◽  
Cellular Model ◽  
Neuronal Precursor Cells ◽  
Age Related ◽  
Epigenetic Age

AbstractInduced pluripotent stem cells (iPSCs) and their differentiated neurons (iPSC-neurons) are a widely used cellular model in the research of the central nervous system. However, it is unknown how well they capture age-associated processes, particularly given that pluripotent cells are only present during the early stages of mammalian development. Epigenetic clocks utilize coordinated age-associated changes in DNA methylation to make predictions that correlate strongly with chronological age, and is has been shown that the induction of pluripotency rejuvenates predicted epigenetic age. As existing clocks are not optimized for the study of brain development, to investigate more precisely the epigenetic age of iPSCs and iPSC-neurons, here, we establish the fetal brain clock (FBC), a bespoke epigenetic clock trained in prenatal neurodevelopmental samples. Our data show that the FBC outperforms other established epigenetic clocks in predicting the age of fetal brain samples. We then applied the FBC to DNA methylation data of cellular datasets that have profiled iPSCs and iPSC-derived neuronal precursor cells and neurons and find that these cell types are characterized by a fetal epigenetic age. Furthermore, while differentiation from iPSCs to neurons significantly increases the epigenetic age, iPSC-neurons are still predicted as having fetal epigenetic age. Together our findings reiterate the need for better understanding of the limitations of existing epigenetic clocks for answering biological research questions and highlight a potential limitation of iPSC-neurons as a cellular model for the research of age-related diseases as they might not fully recapitulate an aged phenotype.

scholarly journals Epigenetic clock and methylation studies in the rhesus macaque

GeroScience ◽  
2021 ◽  
Author(s):  
Steve Horvath ◽  
Joseph A. Zoller ◽  
Amin Haghani ◽  
Anna J. Jasinska ◽  
Ken Raj ◽  
...  
Keyword(s):  
Cerebral Cortex ◽  
Rhesus Macaque ◽  
Mammalian Species ◽  
Vervet Monkey ◽  
Chronological Age ◽  
Biological Research ◽  
Epigenetic Clock ◽  
Methylation Array ◽  
Tissue Samples ◽  
Age Related

AbstractMethylation levels at specific CpG positions in the genome have been used to develop accurate estimators of chronological age in humans, mice, and other species. Although epigenetic clocks are generally species-specific, the principles underpinning them appear to be conserved at least across the mammalian class. This is exemplified by the successful development of epigenetic clocks for mice and several other mammalian species. Here, we describe epigenetic clocks for the rhesus macaque (Macaca mulatta), the most widely used nonhuman primate in biological research. Using a custom methylation array (HorvathMammalMethylChip40), we profiled n = 281 tissue samples (blood, skin, adipose, kidney, liver, lung, muscle, and cerebral cortex). From these data, we generated five epigenetic clocks for macaques. These clocks differ with regard to applicability to different tissue types (pan-tissue, blood, skin), species (macaque only or both humans and macaques), and measure of age (chronological age versus relative age). Additionally, the age-based human-macaque clock exhibits a high age correlation (R = 0.89) with the vervet monkey (Chlorocebus sabaeus), another Old World species. Four CpGs within the KLF14 promoter were consistently altered with age in four tissues (adipose, blood, cerebral cortex, skin). Future studies will be needed to evaluate whether these epigenetic clocks predict age-related conditions in the rhesus macaque.

armDNA: A functional beta model for detecting age-related genomewide DNA methylation marks

2016 ◽  
Vol 27 (9) ◽  
pp. 2627-2640
Author(s):  
Chenyang Wang ◽  
Qi Shen ◽  
Li Du ◽  
Jinfeng Xu ◽  
Hong Zhang
Keyword(s):  
Dna Methylation ◽  
Association Studies ◽  
Rapid Development ◽  
Complex Diseases ◽  
Real Data ◽  
Wald Test ◽  
Methylation Data ◽  
Unknown Parameters ◽  
Diagnosis And Prognosis ◽  
Age Related

DNA methylation has been shown to play an important role in many complex diseases. The rapid development of high-throughput DNA methylation scan technologies provides great opportunities for genomewide DNA methylation-disease association studies. As methylation is a dynamic process involving time, it is quite plausible that age contributes to its variation to a large extent. Therefore, in analyzing genomewide DNA methylation data, it is important to identify age-related DNA methylation marks and delineate their functional relationship. This helps us to better understand the underlying biological mechanism and facilitate early diagnosis and prognosis analysis of complex diseases. We develop a functional beta model for analyzing DNA methylation data and detecting age-related DNA methylation marks on the whole genome by naturally taking sampling scheme into account and accommodating flexible age-methylation dynamics. We focus on DNA methylation data obtained through the widely used bisulfite conversion technique and propose to use a beta model to relate the DNA methylation level to the age. Adjusting for certain confounders, the functional age effect is left completely unspecified, offering great flexibility and allowing extra data dynamics. An efficient algorithm is developed for estimating unknown parameters, and the Wald test is used to detect age-related DNA methylation marks. Simulation studies and several real data applications were provided to demonstrate the performance of the proposed method.

scholarly journals AltumAge: A Pan-Tissue DNA-Methylation Epigenetic Clock Based on Deep Learning

2021 ◽  
Author(s):  
Lucas Paulo de Lima ◽  
Louis R Lapierre ◽  
Ritambhara Singh
Keyword(s):  
Dna Methylation ◽  
Deep Learning ◽  
Placental Tissue ◽  
Training Data ◽  
Data Sets ◽  
Epigenetic Clock ◽  
Neural Network Approach ◽  
Cpg Sites ◽  
Age Related ◽  
Model Predictions

Several age predictors based on DNA methylation, dubbed epigenetic clocks, have been created in recent years. Their accuracy and potential for generalization vary widely based on the training data. Here, we gathered 143 publicly available data sets from several human tissues to develop AltumAge, a highly accurate and precise age predictor based on deep learning. Compared to Horvath's 2013 model, AltumAge performs better across both normal and malignant tissues and is more generalizable to new data sets. Interestingly, it can predict gestational week from placental tissue with low error. Lastly, we used deep learning interpretation methods to learn which methylation sites contributed to the final model predictions. We observed that while most important CpG sites are linearly related to age, some highly-interacting CpG sites can influence the relevance of such relationships. We studied the associated genes of these CpG sites and found literary evidence of their involvement in age-related gene regulation. Using chromatin annotations, we observed that the CpG sites with the highest contribution to the model predictions were related to heterochromatin and gene regulatory regions in the genome. We also found age-related KEGG pathways for genes containing these CpG sites. In general, neural networks are better predictors due to their ability to capture complex feature interactions compared to the typically used regularized linear regression. Altogether, our neural network approach provides significant improvement and flexibility to current epigenetic clocks without sacrificing model interpretability.

scholarly journals Castration delays epigenetic aging and feminises DNA methylation at androgen-regulated loci

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Victoria J Sugrue ◽  
Joseph Alan Zoller ◽  
Pritika Narayan ◽  
Ake T Lu ◽  
Oscar J Ortega-Recalde ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Mammalian Species ◽  
Absolute Error ◽  
Ovis Aries ◽  
Receptor Expression ◽  
Chronological Age ◽  
Epigenetic Clock ◽  
Aging Rate ◽  
Cpg Dinucleotides ◽  
Mouse Tissues

In mammals, females generally live longer than males. Nevertheless, the mechanisms underpinning sex-dependent longevity are currently unclear. Epigenetic clocks are powerful biological biomarkers capable of precisely estimating chronological age and identifying novel factors influencing the aging rate using only DNA methylation data. In this study, we developed the first epigenetic clock for domesticated sheep (Ovis aries), which can predict chronological age with a median absolute error of 5.1 months. We have discovered that castrated male sheep have a decelerated aging rate compared to intact males, mediated at least in part by the removal of androgens. Furthermore, we identified several androgen-sensitive CpG dinucleotides that become progressively hypomethylated with age in intact males, but remain stable in castrated males and females. Comparable sex-specific methylation differences in MKLN1 also exist in bat skin and a range of mouse tissues that have high androgen receptor expression, indicating it may drive androgen-dependent hypomethylation in divergent mammalian species. In characterising these sites, we identify biologically plausible mechanisms explaining how androgens drive male-accelerated aging.

scholarly journals Castration delays epigenetic aging and feminises DNA methylation at androgen-regulated loci

2020 ◽  
Author(s):  
VJ Sugrue ◽  
JA Zoller ◽  
P Narayan ◽  
AT Lu ◽  
OJ Ortega-Recalde ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Mammalian Species ◽  
Accelerated Aging ◽  
Absolute Error ◽  
Ovis Aries ◽  
Chronological Age ◽  
Epigenetic Clock ◽  
Mouse Muscle ◽  
Aging Rate ◽  
Cpg Dinucleotides

SUMMARYIn mammals, females generally live longer than males. Nevertheless, the mechanisms underpinning sex-dependent longevity are currently unclear. Epigenetic clocks are powerful biological biomarkers capable of precisely estimating chronological age using only DNA methylation data. These clocks have been used to identify novel factors influencing the aging rate, but few studies have examined the performance of epigenetic clocks in divergent mammalian species. In this study, we developed the first epigenetic clock for domesticated sheep (Ovis aries), and using 185 CpG sites can predict chronological age with a median absolute error of 5.1 months from ear punch and blood samples. We have discovered that castrated male sheep have a decelerated aging rate compared to intact males, mediated at least in part by the removal of androgens. Furthermore, we identified several androgen-sensitive CpG dinucleotides that become progressively hypomethylated with age in intact males, but remain stable in castrated males and females. Many of these androgen sensitive demethylating sites are regulatory in nature and located in genes with known androgen-dependent regulation, such as MKLN1, LMO4 and FN1. Comparable sex-specific methylation differences in MKLN1 also exist in mouse muscle (p=0.003) but not blood, indicating that androgen dependent demethylation exists in multiple mammalian groups, in a tissue-specific manner. In characterising these sites, we identify biologically plausible mechanisms explaining how androgens drive male-accelerated aging.

scholarly journals Mammalian Co-methylation Network Analysis of Species Characteristics

2021 ◽  
Vol 5 (Supplement_1) ◽  
pp. 676-676
Author(s):  
Amin Haghani ◽  
Steve Horvath
Keyword(s):  
Dna Methylation ◽  
Network Analysis ◽  
Growth Hormone Receptor ◽  
Mammalian Species ◽  
Tissue Type ◽  
Maximum Lifespan ◽  
Age Related ◽  
Species Analysis ◽  
Species Characteristics ◽  
Highly Correlated

Abstract The comparative cross-species analysis is a powerful tool to resolve the mysteries of evolution and phenotypic disparities among animals. This is the first network analysis of 10,000 DNA methylome data from 176 mammalian species to identify co-methylation modules that relate to individual (age, sex, tissue type) and species characteristics (e.g. phylogenetic order, maximum lifespan, adult weight). The unexpected correlation between DNA methylation and species were sufficiently strong to allow the construction of phyloepigenetic trees that parallel the phylogenetic tree. Weighted correlation network analysis identified 55 distinct co-methylation modules, i.e. sets of highly correlated CpGs. 31 of these modules are readily interpretable in terms of their relationship to age, maximum lifespan, tissue type etc. An age-related module was perturbed by gold standard anti-aging interventions in mice such as caloric restriction or growth hormone receptor knock outs. Our module-based analysis greatly enhances our biological understanding of age-related changes in DNA methylation across many species.

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