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Abstract Cellular senescence is a phenotypic state that contributes to the progression of age-related disease through secretion of pro-inflammatory factors known as the senescence-associated secretory phenotype (SASP). Understanding the process by which healthy cells become senescent and develop SASP factors is critical for improving the identification of senescent cells and, ultimately, understanding tissue dysfunction. Here, we reveal how the duration of cellular stress modulates the SASP in distinct subpopulations of senescent cells. We used multiplex, single-cell imaging to build a proteomic map of senescence induction in human epithelial cells induced to senescence over the course of 31 days. We map how the expression of SASP proteins increases alongside other known senescence markers such as p53, p21, and p16INK4a. The aggregated population of cells responded to etoposide with an accumulation of stress response factors over the first 11 days, followed by a plateau in most proteins. At the single-cell level, however, we identified two distinct senescence cell populations, one defined primarily by larger nuclear area and the second by higher protein concentrations. Trajectory inference suggested that cells took one of two discrete molecular paths from unperturbed healthy cells, through a common transitional subpopulation, and ending at the discrete terminal senescence phenotypes. Our results underscore the importance of using single-cell proteomics to identify the mechanistic pathways governing the transition from senescence induction to a mature state of senescence characterized by the SASP.
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Untargeted Lipidomics Highlight the Depletion of Deoxyceramides during Therapy‐Induced Senescence
Abstract Therapy‐induced senescence is a state of cell cycle arrest that occurs as a response to various chemotherapeutic reagents, especially ones that cause DNA damage. Senescent cells display resistance to cell death and can impair the efficacy of chemotherapeutic strategies. Since lipids can exhibit pro‐survival activity, it is envisioned in this article that probing the lipidome could provide insights into novel lipids that are involved in senescence. Therefore, a tissue culture model system is established and the cellular lipidomes of senescent and proliferating cells are comparatively analyzed. Out of thousands of features detected, 17 species are identified that show significant changes in senescent cells. The majority of these species (11 out of 17) are atypical sphingolipids, 1‐deoxyceramides/dihydroceramides, which are produced as a result of the utilization of alanine, instead of serine during sphingolipid biosynthesis. These lipids are depleted in senescent cells. Elevating the levels of deoxyceramides by supplementing the growth medium with metabolic precursors or by directly adding deoxyceramide result in decreased senescence, suggesting that these species might play a key role in this process.
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- Award ID(s):
- 1817468
- PAR ID:
- 10458070
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- PROTEOMICS
- Volume:
- 20
- Issue:
- 10
- ISSN:
- 1615-9853
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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