Inter-tissue convergence of gene expression during ageing suggests age-related loss of tissue and cellular identity
- Middle East Technical University, Turkey
- Shanghai Institutes for Biological Sciences, China
- Skolkovo Institute of Science and Technology, Russian Federation
- Leibniz Institute on Aging - Fritz Lipmann Institute, Germany
Abstract
Developmental trajectories of gene expression may reverse in their direction during ageing, a phenomenon previously linked to cellular identity loss. Our analysis of cerebral cortex, lung, liver and muscle transcriptomes of 16 mice, covering development and ageing intervals, revealed widespread but tissue-specific ageing-associated expression reversals. Cumulatively, these reversals create a unique phenomenon: mammalian tissue transcriptomes diverge from each other during postnatal development, but during ageing, they tend to converge towards similar expression levels, a process we term Divergence followed by Convergence, or DiCo. We found that DiCo was most prevalent among tissue-specific genes and associated with loss of tissue identity, which is confirmed using data from independent mouse and human datasets. Further, using publicly available single-cell transcriptome data, we showed that DiCo could be driven both by alterations in tissue cell type composition and also by cell-autonomous expression changes within particular cell types.
Data availability
Sequencing data generated for this study have been deposited in GEO under accession code GSE167665. All data analysed during this study are included in the manuscript and supporting files. Source data files have been provided for all figures and figure supplements.Four additional and previously published datasets are used in this study:Jonker et al. 2013, GTEx Consortium et al. 2017, Schaum et al. 2020, and Tabula Muris Consortium 2020.
-
Bulk RNA-seq of mice covering the whole lifespan (2 days to 904 days) from four tissuesNCBI Gene Expression Omnibus, GSE167665.
-
Aging ExperimentNCBI Gene Expression Omnibus, GSE34378.
-
Official data release for Tabula Muris Senisfigshare, https://doi.org/10.6084/m9.figshare.12654728.v1.
-
Tabula Muris Senis: Bulk sequencingNCBI Gene Expression Omnibus, GSE132040.
Article and author information
Author details
Philipp Khaitovich
Handan Melike Dönertaş
Funding
European Molecular Biology Laboratory
- Handan Melike Dönertaş
Scientific and Technological Council of Turkey (2232)
- Mehmet Somel
Science Academy BAGEP Awards
- Mehmet Somel
METU Internal Grant
- Mehmet Somel
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: Post-mortem samples were obtained from 16 C57BL/6J mice aged between 2 days and 904 days. All mouse experiments were overseen by the Institutional Animal Welfare Officer of the Max Planck Institute for Evolutionary Anthropology (MPI-EVA). They were performed according to the German Animal Welfare Legislation, ("Tierschutzgesetz") and registered with the Federal State Authority Landesdirektion Sachsen (No. 24-9162. 11-01 (T62/08)). The mice were sacrificed for reasons independent of this study, their tissues were harvested and frozen immediately, and stored at -80{degree sign}C.
Human subjects: Data involving human subjects were obtained from a published dataset, GTEx portal (https://www.gtexportal.org/home/datasets, with accession phs000424.v8.p2). Hence, no ethical statement is required.
Copyright
© 2022, Izgi et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
Metrics
-
- 4,760
- views
-
- 569
- downloads
-
- 37
- citations
Views, downloads and citations are aggregated across all versions of this paper published by eLife.
Download links
A two-part list of links to download the article, or parts of the article, in various formats.
Downloads (link to download the article as PDF)
Open citations (links to open the citations from this article in various online reference manager services)
Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)
Inter-tissue convergence of gene expression during ageing suggests age-related loss of tissue and cellular identity
eLife 11:e68048.
https://doi.org/10.7554/eLife.68048
Further reading
-
- Chromosomes and Gene Expression
- Genetics and Genomics
Among the major classes of RNAs in the cell, tRNAs remain the most difficult to characterize via deep sequencing approaches, as tRNA structure and nucleotide modifications can each interfere with cDNA synthesis by commonly-used reverse transcriptases (RTs). Here, we benchmark a recently-developed RNA cloning protocol, termed Ordered Two-Template Relay (OTTR), to characterize intact tRNAs and tRNA fragments in budding yeast and in mouse tissues. We show that OTTR successfully captures both full-length tRNAs and tRNA fragments in budding yeast and in mouse reproductive tissues without any prior enzymatic treatment, and that tRNA cloning efficiency can be further enhanced via AlkB-mediated demethylation of modified nucleotides. As with other recent tRNA cloning protocols, we find that a subset of nucleotide modifications leave misincorporation signatures in OTTR datasets, enabling their detection without any additional protocol steps. Focusing on tRNA cleavage products, we compare OTTR with several standard small RNA-Seq protocols, finding that OTTR provides the most accurate picture of tRNA fragment levels by comparison to "ground truth" Northern blots. Applying this protocol to mature mouse spermatozoa, our data dramatically alter our understanding of the small RNA cargo of mature mammalian sperm, revealing a far more complex population of tRNA fragments - including both 5′ and 3′ tRNA halves derived from the majority of tRNAs – than previously appreciated. Taken together, our data confirm the superior performance of OTTR to commercial protocols in analysis of tRNA fragments, and force a reappraisal of potential epigenetic functions of the sperm small RNA payload.
-
- Cell Biology
- Genetics and Genomics
A glaucoma polygenic risk score (PRS) can effectively identify disease risk, but some individuals with high PRS do not develop glaucoma. Factors contributing to this resilience remain unclear. Using 4,658 glaucoma cases and 113,040 controls in a cross-sectional study of the UK Biobank, we investigated whether plasma metabolites enhanced glaucoma prediction and if a metabolomic signature of resilience in high-genetic-risk individuals existed. Logistic regression models incorporating 168 NMR-based metabolites into PRS-based glaucoma assessments were developed, with multiple comparison corrections applied. While metabolites weakly predicted glaucoma (Area Under the Curve = 0.579), they offered marginal prediction improvement in PRS-only-based models (p=0.004). We identified a metabolomic signature associated with resilience in the top glaucoma PRS decile, with elevated glycolysis-related metabolites—lactate (p=8.8E-12), pyruvate (p=1.9E-10), and citrate (p=0.02)—linked to reduced glaucoma prevalence. These metabolites combined significantly modified the PRS-glaucoma relationship (Pinteraction = 0.011). Higher total resilience metabolite levels within the highest PRS quartile corresponded to lower glaucoma prevalence (Odds Ratiohighest vs. lowest total resilience metabolite quartile=0.71, 95% Confidence Interval = 0.64–0.80). As pyruvate is a foundational metabolite linking glycolysis to tricarboxylic acid cycle metabolism and ATP generation, we pursued experimental validation for this putative resilience biomarker in a human-relevant Mus musculus glaucoma model. Dietary pyruvate mitigated elevated intraocular pressure (p=0.002) and optic nerve damage (p<0.0003) in Lmx1bV265D mice. These findings highlight the protective role of pyruvate-related metabolism against glaucoma and suggest potential avenues for therapeutic intervention.
