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. 2021 Feb 1;20(2):e13310. doi: 10.1111/acel.13310

FIGURE 3.

FIGURE 3

Aged ALDH+CD44+ keratinocyte stem cells exhibit decreased p53 expression and activity compared with adult. (a) Immunofluorescence study showing p53 nuclear expression and p21 nuclear expression (evidence for p53 activity) in adult and aged keratinocyte SCs. Asterisks indicate keratinocyte SCs positive for p53 and p21 nuclear expression. Negative control without primary antibody. Scale bars 10 µm. Upper histogram showing a significant decrease for ALDH+CD44+ SCs, in p53 and p53/p21 nuclear expression in aged versus adult (n = 3, separate individuals, 100 ALDH+CD44+ SCs per sample). Also, lower histogram showing a trend toward a decrease for ALDH−CD44− non‐SCs in p53 (p = 0.19) and p53/p21 (p = 0.06) nuclear expression in aged versus adult (n = 3, separate individuals, 100 ALDH−CD44− non‐SCs per sample). Values are expressed as mean ±SEM and analyzed using a Student's t test. *p < 0.05. (b) RNA sequencing of human aged versus adult SCs and non‐SCs. (c) Volcano plot displaying differentially expressed genes between aged SCs and adult SCs. The red dots represent the transcripts belonging to the p53 signaling pathway family. Positive x‐values represent up‐regulation and negative x‐values represent down‐regulation. (d) Underlying the decreased p53 signaling pathway (KEGG analysis) in aged versus adult SCs were positive regulators of the p53 pathway that show decreased expression with age and negative regulators that show increased expression with age