2022 Articles

Mahdi Moqri, Andrea Cipriano, Daniel Nachun, Tara Murty, Guilherme de Sena Brandine, Sajede Rasouli, Andrei Tarkhov, Karolina A. Aberg, Edwin van den Oord, Wanding Zhou, Andrew Smith, Crystal Mackall, Vadim Gladyshev, Steve Horvath, Michael P. Snyder, Vittorio Sebastiano (2022) PRC2 clock: a universal epigenetic biomarker of aging and rejuvenation. bioRxiv doi: https://doi.org/10.1101/2022.06.03.49460

AbstractDNA methylation (DNAm) is one of the most reliable biomarkers for aging across many mammalian tissues. While the age-dependent global loss of DNAm has been well characterized, age-dependent DNAm gain is less specified. Multiple studies have demonstrated that polycomb repressive complex 2 (PRC2) targets are enriched among the CpG sites which gain methylation with age. However, a systematic whole-genome examination of all PRC2 targets in the context of aging methylome as well as whether these associations are pan-tissue or tissue-specific is lacking. Here, by analyzing DNAm data from different assays and from multiple young and old human and mouse tissues, we found that low-methylated regions (LMRs) which are highly bound by PRC2 in embryonic stem cells gain methylation with age in all examined somatic mitotic cells. We also estimated that this epigenetic change represents around 90% of the age-dependent DNAm gain genome-wide. Therefore, we propose the “PRC2 clock,” defined as the average DNAm in PRC2 LMRs, as a universal biomarker of cellular aging in somatic cells. In addition, we demonstrate the application of this biomarker in the evaluation of different anti-aging interventions, including dietary restriction and partial epigenetic reprogramming. More Information

Kejun Ying, Hanna Liu, Andrei E. Tarkhov, Ake T. Lu, Steve Horvath, Zoltán Kutalik, Xia Shen, Vadim N. Gladyshev (2022) Causal Epigenetic Age Uncouples Damage and Adaptation. bioRxiv doi: https://doi.org/10.1101/2022.10.07.511382.

AbstractMachine learning models based on DNA methylation can be used to predict the age of biological samples, but their interpretability is limited due to the lack of causal inferences. Here, we lever-aged large-scale genetic data and performed epigenome-wide Mendelian Randomization to identify CpG sites causal to aging-related traits. We show that neither the existing epigenetic clocks nor DNA methylation changes are enriched in causal CpG sites. Causal CpGs include similar numbers of sites that contribute to aging and protect against it, yet their combined contribution negatively affects age-related traits. We developed a framework for integrating causal knowledge into epigenetic clock models and constructed DamAge and AdaptAge that measure age-related damaging and adaptive changes, respectively. DamAge acceleration is associated with various adverse conditions (e.g., mortality risk), whereas AdaptAge acceleration is related to beneficial adaptations. Only DamAge is reversed upon cell reprogramming. Our results offer a comprehensive map of CpG sites causal to lifespan and healthspan, allowing to build causal biomarkers of aging and rejuvenation and assess longevity interventions, age reversal, and aging-accelerating events. More Information

Andrei E. Tarkhov, Thomas Lindstrom-Vautrin, Sirui Zhang, Kejun Ying, Mahdi Moqri, Bohan Zhang, Vadim N. Gladyshev (2022) Nature of epigenetic aging from a single-cell perspective. bioRxiv doi: https://doi.org/10.1101/2022.09.26.509592.

AbstractAge-related changes in DNA methylation (DNAm) form the basis for the development of most robust predictors of age, epigenetic clocks, but a clear mechanistic basis for what exactly they quantify is lacking. Here, to clarify the nature of epigenetic aging, we analyzed the aging dynamics of bulk-tissue and single-cell DNAm, together with single-cell DNAm changes during early development. We show that aging DNAm changes are widespread, but are relatively slow and small in amplitude, with DNAm levels trending towards intermediate values and showing increased heterogeneity with age. By considering dominant types of DNAm changes, we find that aging manifests in the exponential decay-like loss or gain of methylation with a universal rate, independent of the initial level of DNAm. We further show that aging is dominated by the stochastic component, yet co-regulated changes are also present during both development and adulthood. We support the finding of stochastic epigenetic aging by direct single-cell DNAm analyses and modeling of aging DNAm trajectories with a stochastic process akin to radiocarbon decay. Finally, we describe a single-cell algorithm for the identification of co-regulated CpG clusters that may provide new opportunities for targeting aging and evaluating longevity interventions. More Information

Jeyoung Bang, Donghyun Kang, Jisu Jung, Tack-Jin Yoo, Myoung Sup Shim, Vadim N Gladyshev, Petra A Tsuji, Dolph L Hatfield, Jin-Hong Kim, Byeong Jae Lee (2022) SEPHS1: Its evolution, function and roles in development and diseases. Arch Biochem Biophys doi: 10.1016/j.abb.2022.109426.

AbstractSelenophosphate synthetase (SEPHS) was originally discovered in prokaryotes as an enzyme that catalyzes selenophosphate synthesis using inorganic selenium and ATP as substrates. However, in contrast to prokaryotes, two paralogs, SEPHS1 and SEPHS2, occur in many eukaryotes. Prokaryotic SEPHS, also known as SelD, contains either cysteine (Cys) or selenocysteine (Sec) in the catalytic domain. In eukaryotes, only SEPHS2 carries out selenophosphate synthesis and contains Sec at the active site. However, SEPHS1 contains amino acids other than Sec or Cys at the catalytic position. Phylogenetic analysis of SEPHSs reveals that the ancestral SEPHS contains both selenophosphate synthesis and another unknown activity, and that SEPHS1 lost the selenophosphate synthesis activity. The three-dimensional structure of SEPHS1 suggests that its homodimer is unable to form selenophosphate, but retains ATPase activity to produce ADP and inorganic phosphate. The most prominent function of SEPHS1 is that it is implicated in the regulation of cellular redox homeostasis. Deficiency of SEPHS1 leads to the disturbance in the expression of genes involved in redox homeostasis. Different types of reactive oxygen species (ROS) are accumulated in response to SEPHS deficiency depending on cell or tissue types. The accumulation of ROS causes pleiotropic effects such as growth retardation, apoptosis, DNA damage, and embryonic lethality. SEPHS1 deficiency in mouse embryos affects retinoic signaling and other related signaling pathways depending on the embryonal stage until the embryo dies at E11.5. Dysregulated SEPHS1 is associated with the pathogenesis of various diseases including cancer, Crohn’s disease, and osteoarthritis. More Information

Bohan Zhang, Andrei E. Tarkhov, Wil Ratzan, Kejun Ying, Mahdi Moqri, Jesse R. Poganik, Benjamin Barre, Alexandre Trapp, Joseph A. Zoller, Amin Haghani, Steve Horvath, Leonid Peshkin, Vadim N. Gladyshev(2022) Epigenetic profiling and incidence of disrupted development point to gastrulation as aging ground zero in Xenopus laevis. bioRxive doi: https://doi.org/10.1101/2022.08.02.502559

AbstractRecent studies suggest the existence of a natural rejuvenation event during early embryonic development of mice, followed by epigenetic aging. Here, by profiling embryonic DNA methylation in the African clawed frog, Xenopus laevis, we found that the epigenetic entropy basepoint maps to the gastrulation stage of embryogenesis and corresponds to a rapid increase in embryo transcript abundance. We further developed a frog aging clock, revealing that this species epigenetically ages. Application of this clock to developmental stages identified a decrease in epigenetic age during early embryogenesis, with the minimal age reached around gastrulation. By examining individual developmental trajectories of 6,457 embryos, we found that this stage is also accompanied by a higher incidence of disrupted development. Taken together, our data point to gastrulation as a critical stage for aging and natural rejuvenation, characterized by the lowest epigenetic age, increased mortality, nadir of DNA methylation entropy and rapid increase in embryo transcript abundance, defining aging ground zero as the basepoint where rejuvenation ends and the aging process begins. More Information

Jesse R. Poganik, Bohan Zhang, Gurpreet S. Baht, Csaba Kerepesi, Sun Hee Yim, Ake T. Lu, Amin Haghani, Tong Gong, Anna M. Hedman, Ellika Andolf, Göran Pershagen, Catarina Almqvist, James P. White, Steve Horvath, Vadim N. Gladyshev (2022) Biological age is increased by stress and restored upon recovery. bioRxive doi:https://doi.org/10.1101/2022.05.04.490686

AbstractAging is classically conceptualized as an ever-increasing trajectory of damage accumulation and loss of function, leading to increases in morbidity and mortality. However, recent in vitro studies have raised the possibility of age reversal. Here, we report that biological age is fluid and exhibits rapid changes in both directions. By applying advanced epigenetic aging clocks, we find that the biological age of young mice is increased by heterochronic parabiosis and restored following surgical detachment of animals. We also identify transient changes in biological age during major surgery, pregnancy, and severe COVID-19 in humans and/or mice. Together, these data show that biological age undergoes a rapid increase in response to diverse forms of stress, which is reversed following recovery from stress. Our study uncovers a new layer of aging dynamics that should be considered in future studies. Elevation of biological age by stress may be a quantifiable and actionable target for future interventions. More Information

Shindyapina AV, Cho Y, Kaya A, Tyshkovskiy A, Castro JP, Deik A, Gordevicius J, Poganik JR, Clish CB, Horvath S, Peshkin L, Gladyshev VN (2022) Rapamycin treatment during development extends life span and health span of male mice and Daphnia magna. Science Advances 8, 37.

AbstractDevelopment is tightly connected to aging, but whether pharmacologically targeting development can extend life remains unknown. Here, we subjected genetically diverse UMHET3 mice to rapamycin for the first 45 days of life. The mice grew slower and remained smaller than controls for their entire lives. Their reproductive age was delayed without affecting offspring numbers. The treatment was sufficient to extend the median life span by 10%, with the strongest effect in males, and helped to preserve health as measured by frailty index scores, gait speed, and glucose and insulin tolerance tests. Mechanistically, the liver transcriptome and epigenome of treated mice were younger at the completion of treatment. Analogous to mice, rapamycin exposure during development robustly extended the life span of Daphnia magna and reduced its body size. Overall, the results demonstrate that short-term rapamycin treatment during development is a novel longevity intervention that acts by slowing down development and aging, suggesting that aging may be targeted already early in life. More Information

Kerepesi C, Meer MV, Ablaeva J, Amoroso VG, Lee SG, Zhang B, Gerashchenko MV, Trapp A, Yim SH, Lu AT, Levine ME, Seluanov A, Horvath S, Park TJ, Gorbunova V, Gladyshev VN (2022) Epigenetic aging of the demographically non-aging naked mole-rat. Nature Communications 13, 355.

AbstractThe naked mole-rat (NMR) is an exceptionally long-lived rodent that shows no increase of mortality with age, defining it as a demographically non-aging mammal. Here, we perform bisulfite sequencing of the blood of > 100 NMRs, assessing > 3 million common CpG sites. Unsupervised clustering based on sites whose methylation correlates with age reveals an age-related methylome remodeling, and we also observe a methylome information loss, suggesting that NMRs age. We develop an epigenetic aging clock that accurately predicts the NMR age. We show that these animals age much slower than mice and much faster than humans, consistent with their known maximum lifespans. Interestingly, patterns of age-related changes of clock sites in Tert and Prpf19 differ between NMRs and mice, but there are also sites conserved between the two species. Together, the data indicate that NMRs, like other mammals, epigenetically age even in the absence of demographic aging of this species. More Information

Zhang B, Trapp A, Kerepesi C, Gladyshev VN (2022) Emerging rejuvenation strategies-Reducing the biological age. Aging Cell 21, e13538.

Abstract Several interventions have recently emerged that were proposed to reverse rather than just attenuate aging, but the criteria for what it takes to achieve rejuvenation remain controversial. Distinguishing potential rejuvenation therapies from other longevity interventions, such as those that slow down aging, is challenging, and these anti-aging strategies are often referred to interchangeably. We suggest that the prerequisite for a rejuvenation intervention is a robust, sustained, and systemic reduction in biological age, which can be assessed by biomarkers of aging, such as epigenetic clocks. We discuss known and putative rejuvenation interventions and comparatively analyze them to explore underlying mechanisms. More Information

Mariotti M, Kerepesi C, Oliveros W, Mele M, Gladyshev VN (2022) Deterioration of the human transcriptome with age due to increasing intron retention and spurious splicing. bioRxiv, 10.1101/2022.03.14.484341

Abstract Adult aging is characterized by a progressive deterioration of biological functions at physiological, cellular and molecular levels, but its damaging effects on the transcriptome are not well characterized. Here, by analyzing splicing patterns in ∼1,000 human subjects sampled across multiple tissues, we found that splicing fidelity declines with age. Most prominently, genuine introns fail to be spliced out, manifesting as a broad surge in intron retention, and this is exacerbated by the increase in diverse spurious exon-exon junctions with age. Both of these effects are prominently detected in the majority of human tissues. Collectively, they result in the progressive deterioration of the active transcriptome, wherein functional mRNAs are increasingly diluted with non-functional splicing isoforms. We discuss the concept of “splicing damage” and formulate methods to quantify it. Using these tools, we show that splicing damage increases both with age and with the incidence of diseases. Altogether, this work uncovers transcriptome damage as a critical molecular indicator of human aging and healthspan. More Information

Meron E, Thaysen M, Angeli S, Antebi A, Barzilai N, Baur JA, Bekker-Jensen S, Birkisdottir M, Bischof E, Bruening J, Brunet A, Buchwalter A, Cabreiro F, Fortney K, Freund A, Georgievskaya A, Gladyshev VN, Glass D, Golato T, Gorbunova V, Hoejimakers J, Houtkooper RH, Jager S, Jaksch F, Janssens G, Jensen MB, Kaeberlein M, Karsenty G, de Keizer P, Kennedy B, Kirkland JL, Kjaer M, Kroemer G, Lee KF, Lemaitre JM, Liaskos D, Longo VD, Lu YX, MacArthur MR, Maier AB, Manakanatas C, Mitchell SJ, Moskalev A, Niedernhofer L, Ozerov I, Partridge L, Passegué E, Petr MA, Peyer J, Radenkovic D, Rando TA, Rattan S, Riedel CG, Rudolph L, Ai R, Serrano M, Schumacher B, Sinclair DA, Smith R, Suh Y, Taub P, Trapp A, Trendelenburg AU, Valenzano DR, Verburgh K, Verdin E, Vijg J, Westendorp RGJ, Zonari A, Bakula D, Zhavoronkov A, Scheibye-Knudsen M (2022) Meeting Report: Aging Research and Drug Discovery. Aging 14, 530-543.

Abstract Aging is the single largest risk factor for most chronic diseases, and thus possesses large socioeconomic interest to continuously aging societies. Consequently, the field of aging research is expanding alongside a growing focus from the industry and investors in aging research. This year’s 8th Annual Aging Research and Drug Discovery (ARDD) meeting was organized as a hybrid meeting from August 30th to September 3rd 2021 with more than 130 attendees participating on-site at the Ceremonial Hall at University of Copenhagen, Denmark, and 1800 engaging online. The conference comprised of presentations from 75 speakers focusing on new research in topics including mechanisms of aging and how these can be modulated as well as the use of AI and new standards of practices within aging research. This year, a longevity workshop was included to build stronger connections with the clinical community. More Information

Kang D, Lee J, Jung J, Carlson BA, Chang MJ, Chang CB, Kang SB, Lee BC, Gladyshev VN, Hatfield DL, Lee BJ, Kim JH (2022) Selenophosphate synthetase 1 deficiency exacerbates osteoarthritis by dysregulating redox homeostasis. Nature Communications 13, 779.

AbstractAging and mechanical overload are prominent risk factors for osteoarthritis (OA), which lead to an imbalance in redox homeostasis. The resulting state of oxidative stress drives the pathological transition of chondrocytes during OA development. However, the specific molecular pathways involved in disrupting chondrocyte redox homeostasis remain unclear. Here, we show that selenophosphate synthetase 1 (SEPHS1) expression is downregulated in human and mouse OA cartilage. SEPHS1 downregulation impairs the cellular capacity to synthesize a class of selenoproteins with oxidoreductase functions in chondrocytes, thereby elevating the level of reactive oxygen species (ROS) and facilitating chondrocyte senescence. Cartilage-specific Sephs1 knockout in adult mice causes aging-associated OA, and augments post-traumatic OA, which is rescued by supplementation of N-acetylcysteine (NAC). Selenium-deficient feeding and Sephs1 knockout have synergistic effects in exacerbating OA pathogenesis in mice. Therefore, we propose that SEPHS1 is an essential regulator of selenium metabolism and redox homeostasis, and its dysregulation governs the progression of OA. More Information

Lee HM, Choi DW, Kim S, Lee A, Kim M, Roh YJ, Jo YH, Cho HY, Lee HJ, Lee SR, Tarrago L, Gladyshev VN, Kim JH, Lee BC (2022) Biosensor-Linked Immunosorbent Assay for the Quantification of Methionine Oxidation in Target Proteins. ACS Sensors 7, 131-141.

Abstract Methionine oxidation is involved in regulating the protein activity and often leads to protein malfunction. However, tools for quantitative analyses of protein-specific methionine oxidation are currently unavailable. In this work, we developed a biological sensor that quantifies oxidized methionine in the form of methionine-R-sulfoxide in target proteins. The biosensor “tpMetROG” consists of methionine sulfoxide reductase B (MsrB), circularly permuted yellow fluorescent protein (cpYFP), thioredoxin, and protein G. Protein G binds to the constant region of antibodies against target proteins, specifically capturing them. Then, MsrB reduces the oxidized methionine in these proteins, leading to cpYFP fluorescence changes. We assessed this biosensor for quantitative analysis of methionine-R-sulfoxide in various proteins, such as calmodulin, IDLO, LegP, Sacde, and actin. We further developed an immunosorbent assay using the biosensor to quantify methionine oxidation in specific proteins such as calmodulin in animal tissues. The biosensor-linked immunosorbent assay proves to be an indispensable tool for detecting methionine oxidation in a protein-specific manner. This is a versatile tool for studying the redox biology of methionine oxidation in proteins. More Information

Tian R, Han K, Geng Y, Yang C, Shi C, Thomas PB, Pearce C, Moffatt K, Ma S, Xu S, Yang G, Zhou X, Gladyshev VN, Liu X, Fisher DO, Chopin LK, Leiner NO, Baker AM, Fan G, Seim I (2022) A chromosome-level genome of Antechinus flavipes provides a reference for an Australian marsupial genus with male death after mating. Molecular Ecology Resources 22, 740-754.

Abstract The 15 species of small carnivorous marsupials that comprise the genus Antechinus exhibit semelparity, a rare life-history strategy in mammals where synchronized death occurs after one breeding season. Antechinus males, but not females, age rapidly (demonstrate organismal senescence) during the breeding season and show promise as new animal models of ageing. Some antechinus species are also threatened or endangered. Here, we report a chromosome-level genome of a male yellow-footed antechinus Antechinus flavipes. The genome assembly has a total length of 3.2 Gb with a contig N50 of 51.8 Mb and a scaffold N50 of 636.7 Mb. We anchored and oriented 99.7% of the assembly on seven pseudochromosomes and found that repetitive DNA sequences occupy 51.8% of the genome. Draft genome assemblies of three related species in the subfamily Phascogalinae, two additional antechinus species (Antechinus argentus and A. arktos) and the iteroparous sister species Murexia melanurus, were also generated. Preliminary demographic analysis supports the hypothesis that climate change during the Pleistocene isolated species in Phascogalinae and shaped their population size. A transcriptomic profile across the A. flavipes breeding season allowed us to identify genes associated with aspects of the male die-off. The chromosome-level A. flavipes genome provides a steppingstone to understanding an enigmatic life-history strategy and a resource to assist the conservation of antechinuses. More Information