Figure 3. Biased distribution of extragenic transposons relative to genes.

(A) Extragenic transposons with significantly (sig.) changed expression during aging or cellular senescence show a biased distribution, when mapped back onto the genome, with a preference toward a 5-kb region at the 3′-end of genes when compared to all annotated transposons (all) or randomly permuted transposons (random). Permutation was performed using the bedtools shuffle function. (B) Extragenic transposons whose expression changes during cellular senescence are spread out further from genes compared to aging-associated transposons.

Figure 3—figure supplement 1. Increased readthrough levels with aging and senescence.

Readthrough transcription is increased in fibroblasts isolated from the very old (A, B) and after induction of senescence in vitro (C, D). (A) Readthrough was determined in a region 0–10 kb downstream of genes for a subset of genes that were at least 10 kb away from the nearest neighboring gene (n = 684 regions). The log2 ratio of readthrough to gene expression is plotted across five age groups (adolescent n = 32, young n = 31, middle-aged n = 22, old n = 37, and very old n = 21). (B) As in (A), but data are plotted on a per sample basis. (C) Readthrough was determined in a region 0–10 kb downstream of genes for a subset of genes that were at least 10 kb away from the nearest neighboring gene (n = 1045 regions). The log2 ratio of readthrough to gene expression is plotted for the groups comprising senescence (n = 12) and the non-senescent group (n = 6). (D) As in (D), but data are plotted on a per sample basis and for additional control datasets (serum-starved, immortalized, intermediate passage, and early passage). N = 3 per group.