TERRA expression in different human cell lines. (A) TERRA ONTseq read coverage for 7q and 8p subtelomeres in U2OS, HeLa, and HEK293T. Mapping was performed against the T2T CHM13v2.0/hs1 subtelomeric reference genome. Alignments span 1250 bp regions starting from the first telomeric repeat. The darker and lighter shade lines represent unique and multimapped reads, respectively. The vertical gray lines indicate the position of the most telomere-proximal 29 bp–like repeats. (B) Quantification of the unique and multimapped reads (darker and lighter shades, respectively) within 1250 bp regions as in A for each human subtelomere. Reads are normalized to the corresponding library size. (C) Metaprofiles of uniquely mapped reads for U2OS, HeLa, and HEK293T cells. Note that the read density profiles between 750 and 1250 bp largely derive from Chromosomes 8q, 18q, and 22p only. (D) RT-qPCR quantifications of TERRA transcripts from 5p, 7q/12q, and 16p subtelomeres in the indicated cell lines. Values are normalized to the number of molecules in U2OS cells. Bars and error bars are means and SDs from three independent experiments. P values (Student's t-test) are indicated.
