Biology subjects

Kerepesi, C.

Publications and source records attributed to Kerepesi, C..

3 recordsLinked to original sources

bioRxiv2021

Profiling epigenetic age in single cells

DNA methylation of a defined set of CpG dinucleotides emerged as a critical and precise biomarker of the aging process. Multi-variate machine learning models, known as epigenetic clocks, can exploit quantitative changes in the methylome to predict the age of bulk tissue with remarkable accuracy. However, intrinsic sparsity and digitized methylation in individual cells have so far precluded the assessment of aging in single cell data. Here, we present scAge, a probabilistic approach to determine the epigenetic age of single cells, and validate our results in mice. scAge tissue-specific and multi-cell type single cell clocks correctly recapitulate chronological age of the original tissue, while uncovering the inherent heterogeneity that exists at the single-cell level. The data suggest that while tissues age in a coordinated fashion, some cells age more or less rapidly than others. We show that individual embryonic stem cells exhibit an age close to zero, that certain stem cells in a tissue show a reduced age compared to their chronological age, and that early embryogenesis is associated with the reduction of epigenetic age of individual cells, the latter supporting a natural rejuvenation event during gastrulation. scAge is both robust against the low coverage that is characteristic of single cell sequencing techniques and is flexible for studying any cell type and vertebrate organism of interest. This study demonstrates for the first time the potential for accurate epigenetic age profiling at single-cell resolution.

genomics↗

bioRxiv2021

Epigenetic clocks reveal a rejuvenation event during embryogenesis followed by aging

The notion that germline cells do not age goes back to the 19th century ideas of August Weismann. However, being in a metabolically active state, they accumulate damage and other age-related changes over time, i.e., they age. For new life to begin in the same young state, they must be rejuvenated in the offspring. Here, we developed a new multi-tissue epigenetic clock and applied it, together with other aging clocks, to track changes in biological age during mouse and human prenatal development. This analysis revealed a significant decrease in biological age, i.e. rejuvenation, during early stages of embryogenesis, followed by an increase in later stages. We further found that pluripotent stem cells do not age even after extensive passaging and that the examined epigenetic age dynamics is conserved across species. Overall, this study uncovers a natural rejuvenation event during embryogenesis and suggests that the minimal biological age (the ground zero) marks the beginning of organismal aging.

developmental biology↗

bioRxiv2021

Aging predisposes B cells to malignancy by activating c-Myc and perturbing the genome and epigenome

While cancer is an age-related disease, many cancer studies utilize younger animal models. Here, we uncover how a cancer, B-cell lymphoma, develops as a consequence of a naturally aged system. We show that this malignancy is associated with increased cell size, splenomegaly, and a newly discovered age-associated clonal B-cell (ACBC) population. Driven by exogenous c-Myc activation, hypermethylated promoters and somatic mutations, ACBC cells clonally expand independent of germinal centers (IgM+) and show increased biological age and hypomethylation in partially methylated domains related to mitotic solo-CpGs. Epigenetic changes in transformed mouse B cells are enriched for changes observed in human B-cell lymphomas. Mechanistically, the data suggest that cancerous ACBC cells originate from age-associated B cells, in part involving CD22 protein signaling fostered by the aging microenvironment. Transplantation assays demonstrate that ACBC evolve to become self-sufficient and support malignancy when transferred into young recipients. Inhibition of mTOR or c-Myc in old mice attenuates premalignant changes in B cells during aging and emerges as a therapeutic strategy to delay the onset of age-related lymphoma. Together, we show how aging contributes to B-cell lymphoma through a previously unrecognized mechanism involving cell-intrinsic changes and the aged microenvironment, characterize a model that captures the origin and progression of spontaneous cancer during aging and identify candidate interventions against age-associated lymphoma.

cancer biology↗