Analysis of individual cells identifies cell‐to‐cell variability following induction of cellular senescence

• Published in: Aging cell Vol. 16; no. 5; pp. 1043 - 1050
• Main Authors: Wiley, Christopher D., Flynn, James M., Morrissey, Christapher, Lebofsky, Ronald, Shuga, Joe, Dong, Xiao, Unger, Marc A., Vijg, Jan, Melov, Simon, Campisi, Judith
• Format: Journal Article
• Language: English
• Published: England John Wiley & Sons, Inc 01.10.2017; Anatomical Society - Wiley; John Wiley and Sons Inc
• Subjects: aging; Analysis; BASIC BIOLOGICAL SCIENCES; beta-Galactosidase - genetics; beta-Galactosidase - metabolism; Bleomycin - pharmacology; Cancer; Cell Biology; Cell Cycle Proteins - genetics; Cell Cycle Proteins - metabolism; Cell Line; cellular senescence; Cellular Senescence - drug effects; Cellular Senescence - genetics; cytokines; Cytokines - genetics; Cytokines - metabolism; Fetus; Fibroblasts - cytology; Fibroblasts - drug effects; Fibroblasts - metabolism; Gene expression; Gene Expression Profiling; Gene Expression Regulation; Genes; Genetic Variation; Geriatrics & Gerontology; Humans; Inflammation; Lung - cytology; Lung - drug effects; Lung - metabolism; Microfluidics - instrumentation; Microfluidics - methods; Nanotechnology - instrumentation; Nanotechnology - methods; Original; Physiological aspects; Polymerase Chain Reaction - instrumentation; Polymerase Chain Reaction - methods; Protein Interaction Mapping; Senescence; Signal Transduction; single cell; Single-Cell Analysis - instrumentation; Single-Cell Analysis - methods; Transcriptome; transcriptomics; transcriptomics; single cell; cytokines; cellular senescence; aging
• ISSN: 1474-9718; 1474-9726
• DOI: 10.1111/acel.12632

Summary Senescent cells play important roles in both physiological and pathological processes, including cancer and aging. In all cases, however, senescent cells comprise only a small fraction of tissues. Senescent phenotypes have been studied largely in relatively homogeneous populations of cultured cells. In vivo, senescent cells are generally identified by a small number of markers, but whether and how these markers vary among individual cells is unknown. We therefore utilized a combination of single‐cell isolation and a nanofluidic PCR platform to determine the contributions of individual cells to the overall gene expression profile of senescent human fibroblast populations. Individual senescent cells were surprisingly heterogeneous in their gene expression signatures. This cell‐to‐cell variability resulted in a loss of correlation among the expression of several senescence‐associated genes. Many genes encoding senescence‐associated secretory phenotype (SASP) factors, a major contributor to the effects of senescent cells in vivo, showed marked variability with a subset of highly induced genes accounting for the increases observed at the population level. Inflammatory genes in clustered genomic loci showed a greater correlation with senescence compared to nonclustered loci, suggesting that these genes are coregulated by genomic location. Together, these data offer new insights into how genes are regulated in senescent cells and suggest that single markers are inadequate to identify senescent cells in vivo.