Biology subjects

Harel, I.

Publications and source records attributed to Harel, I..

9 recordsLinked to original sources

bioRxiv2026

A molecular circuit integrates environmental cues to coordinate the exit from developmental dormancy

Diapause is a reversible dormancy state that enables organisms to survive extreme environments. In annual killifishes, embryos use diapause to bridge seasonal drought, but how environmental cues are integrated to trigger exit remains unclear. Here, we combine model-based single-embryo transcriptomics with cross-clade small-molecule screening to define the molecular logic of diapause exit. In the African turquoise killifish (Nothobranchius furzeri), high-resolution profiling uncovered a temporal transcriptional cascade, while transcriptomic-clock analysis revealed reduced transcriptional noise during developmental reactivation. Transcriptome-guided drug-enrichment analysis nominated overlapping compounds across two annual killifish clades, leading to a targeted chemical screen that identified shared activators and inhibitors of diapause exit. Functional assays support a model in which HSP90 integrates temperature-dependent cues with steroid-hormone signaling. Together, these findings reveal shared molecular machinery that couples environmental sensing to developmental timing, aligns diapause exit with favorable conditions, and provides a powerful comparative framework for dissecting vertebrate dormancy control.

developmental biology↗

bioRxiv2024

The cGAS-STING pathway is an in vivo modifier of genomic instability syndromes

Mutations in genes involved in DNA damage repair (DDR) often lead to premature aging syndromes. While recent evidence suggests that inflammation, alongside mutation accumulation and cell death, may drive disease phenotypes, its precise contribution to in vivo pathophysiology remains unclear. Here, by modeling Ataxia Telangiectasia (A-T) and Bloom Syndrome in the African turquoise killifish (N. furzeri), we replicate key phenotypes of DDR syndromes, including infertility, cytoplasmic DNA fragments, and reduced lifespan. The link between DDR defects and inflammation is attributed to the activation of the cGAS-STING pathway and interferon signaling by cytoplasmic DNA. Accordingly, mutating cGAS partially rescues germline defects and senescence in A-T fish. Double mutants also display reversal of telomere abnormalities and suppression of transposable elements, underscoring cGASs non-canonical role as a DDR inhibitor. Our findings emphasize the role of interferon signaling in A-T pathology and identify the cGAS-STING pathway as a potential therapeutic target for genomic instability syndromes.

genetics↗

bioRxiv2023

The germline regulates longevity and somatic repair in a sex-specific manner

Classical evolutionary theories propose tradeoffs between reproduction, damage repair, and lifespan. However, the specific role of the germline in shaping vertebrate aging remains largely unknown. Here, we use the turquoise killifish (N. furzeri) to genetically arrest germline development at discrete stages, and examine how different modes of infertility impact life-history. We first construct a comprehensive single-cell gonadal atlas, providing cell-type-specific markers for downstream phenotypic analysis. Next, we show that germline depletion - but not arresting germline differentiation - enhances damage repair in female killifish. Conversely, germline-depleted males instead showed an extension in lifespan and rejuvenated metabolic functions. Through further transcriptomic analysis, we highlight enrichment of pro-longevity pathways and genes in germline-depleted male killifish and demonstrate functional conservation of how these factors may regulate longevity in germline-depleted C. elegans. Our results therefore demonstrate that different germline manipulation paradigms can yield pronounced sexually dimorphic phenotypes, implying alternative responses to classical evolutionary tradeoffs.

genetics↗

bioRxiv2023

Exploring life-long tissue homeostasis through lineage tracing and cell transplantation

The antagonistic pleiotropy theory of aging predicts functional trade-offs between early-life and late-life fitness. However, empirical evidence for these trade-offs in vertebrates remains scarce, particularly in the context of ecologically relevant life histories. Here, we identify vestigial-like 3 (vgll3), a transcription cofactor previously linked with age at maturity in humans and Atlantic salmon through GWAS studies, as an antagonistically pleiotropic gene in turquoise killifish (Nothobranchius furzeri). By disrupting two conserved vgll3 isoforms, we show that reduction of vgll3, in an isoform- or dose-dependent manner, accelerated male growth and reproductive development. This indicates that vgll3 regulates sexual maturity. However, early-life benefits come at a late-life cost, as older mutant males with a disrupted long isoform develop melanoma-like tumors, validated via transplantation into immunodeficient rag2 models, and exhibit increased age-related mortality rate. These findings highlight vgll3 as a key regulator of vertebrate life-history trade-offs, balancing early-life fitness with late-life disease risks.

genetics↗

bioRxiv2023

A scalable platform for functional interrogation of peptide hormones in fish

Fish display a remarkable diversity of life-history traits, including body size, age at maturity, and longevity. Although pituitary hormones are conserved mediators of life-history transitions, regulatory networks are less understood in fish. However, the relatively long life-cycles and germline-dependent maturation of classical fish models are less compatible with rapid exploration of adult physiology, particularly in females. Here, we describe a high-throughput platform that combines, for the first time, loss- and gain-of-function of peptide hormones in a naturally short-lived fish. As a proof-of-principle, we first manipulate growth by mutating growth hormone (gh1) in the turquoise killifish (N. furzeri). Next, to rescue growth defects, we designed a vector in which hormones are tagged by a self-cleavable fluorescent reporter, and are ectopically expressed using intramuscular electroporation. A single injection of a gh1-T2A-GFP plasmid was sufficient to produce a stable expression of tag-free hormone and rescue growth phenotypes. This, in contrast to current practice for which multiple injections of recombinant hormones are required. We demonstrate the versatility of our platform by rescuing female sterility, which is induced by manipulating the follicle stimulating hormone (fshb). As killifish maturation is germline-independent, both sexes can be explored in genetic models with germline defects. Finally, we describe a doxycycline-inducible system for tunable expression control. Together, this platform significantly advances the state-of-the-art by allowing high-throughput functional dissection of distinct life-history strategies in fish. This method could be multiplexed to facilitate various applications, including optimizing commercially valuable traits in aquaculture, or screening pro-longevity hormonal interventions in aging.

genetics↗

bioRxiv2022

Identification of protein aggregates in the aging vertebrate brain with prion-like andphase separation properties

Protein aggregation, which can sometimes spread in a prion-like manner, is a hallmark of neurodegenerative diseases. However, whether prion-like aggregates form during normal brain aging remains unknown. Here we use quantitative proteomics in the African turquoise killifish to identify protein aggregates that accumulate in old vertebrate brains. These aggregates are enriched for prion-like RNA binding proteins, notably the ATP-dependent RNA helicase DDX5. We validate that DDX5 forms mislocalized cytoplasmic aggregates in the brains of old killifish and mice. Interestingly, DDX5s prion-like domain allows these aggregates to propagate across many generations in yeast. In vitro, DDX5 phase separates into condensates. Mutations that abolish DDX5 prion propagation also impair the proteins ability to phase separate. DDX5 condensates exhibit enhanced enzymatic activity, but they can mature into inactive, solid aggregates. Our findings suggest that protein aggregates with prion-like properties form during normal brain aging, which could have implications for the age-dependency of cognitive decline.

neuroscience↗

bioRxiv2022

Tissue-specific landscape of protein aggregation and quality control in an aging vertebrate

Protein aggregation is a hallmark of age-related neurodegeneration. Yet, aggregation during normal aging and in tissues other than the brain is poorly understood. Here we leverage the African turquoise killifish to systematically profile protein aggregates in seven tissues of an aging vertebrate. Age-dependent aggregation is strikingly tissue-specific, and not simply driven by protein expression differences. Experimental interrogation, combined with machine learning, indicates that this specificity is linked to both protein-autonomous biophysical features and tissue-selective alterations in protein quality control. Co-aggregation of protein quality control machinery during aging may further reduce proteostasis capacity, exacerbating aggregate burden. A segmental progeria model with accelerated aging in specific tissues exhibits selectively increased aggregation in these same tissues. Intriguingly, many age-related protein aggregates arise in wild-type proteins that, when mutated, drive human diseases. Our data chart a comprehensive landscape of protein aggregation during aging and reveal strong, tissue-specific associations with dysfunction and disease. HIGHLIGHTSO_LITissue-specific protein aggregation is prevalent during vertebrate aging C_LIO_LIBoth protein biophysical properties and tissue-specific protein homeostasis patterns impact aggregation C_LIO_LIA segmental progeria model with accelerated aging exhibits selectively increased protein aggregation in affected tissues C_LIO_LIMany aggregates that accumulate during physiological aging are linked to disease C_LI

systems biology↗

bioRxiv2022

Sex-specific regulation of metabolic health and vertebrate lifespan by AMP biosynthesis

Energy homeostasis is disrupted with age, which then fuels multiple age-related pathologies. The AMP-activated protein kinase (AMPK) is the primary sensor of cellular energy in eukaryotes. However, the genetic regulation of vertebrate aging by AMPK remains poorly understood. Here, we manipulate energy levels in the turquoise killifish by mutating APRT, a key enzyme in AMP biosynthesis. These manipulations produced a male-specific lifespan extension and restored metabolic plasticity. Exploring the observed sex differences using an integrated omics approach implicated the mitochondria as an important player. Mechanistically, APRT regulated mitochondrial functions and AMPK activity, mimicking energy starvation in heterozygous cells. A fasting-like state was also detected, particularly in heterozygous males, which leads to resistance to high-fat diet. Finally, life-long intermittent fasting eliminated the male-specific longevity benefits mediated by the APRT mutation. These observations identify the AMP/AMPK axis as a sex-specific regulator of vertebrate longevity and metabolic health.

genetics↗

bioRxiv2018

Remodeling of epigenome and transcriptome landscapes with aging in mice reveals widespread induction of inflammatory responses

Aging is accompanied by the functional decline of tissues. However, a systematic study of epigenomic and transcriptomic changes across tissues during aging is missing. Here we generated chromatin maps and transcriptomes from 4 tissues and one cell type from young, middle-age, and old mice, yielding 143 high-quality datasets. We focused specifically on chromatin marks linked to gene expression regulation and cell identity: histone H3 trimethylation at lysine 4 (H3K4me3), a mark enriched at promoters, and histone H3 acetylation at lysine 27 (H3K27ac), a mark enriched at active enhancers. Epigenomic and transcriptomic landscapes could easily distinguish between ages, and machine learning analysis showed that specific epigenomic states could predict transcriptional changes during aging. Analysis of datasets from all tissues identified recurrent age-related chromatin and transcriptional changes in key processes, including the upregulation of immune system response pathways such as the interferon signaling pathway. The upregulation of interferon response pathway with age was accompanied by increased transcription of various endogenous retroviral sequences. Pathways deregulated during mouse aging across tissues, notably innate immune pathways, were also deregulated with aging in other vertebrate species - African turquoise killifish, rat, and humans - indicating common signatures of age across species. To date, our dataset represents the largest multi-tissue epigenomic and transcriptomic dataset for vertebrate aging. This resource identifies chromatin and transcriptional states that are characteristic of youthful tissues, which could be leveraged to restore aspects of youthful functionality to old tissues.

genomics↗