Chapter 2 Analysis of Average Telomere Length

Telomeres play an important role in ensuring the integrity of the genome. Telomere shortening can lead to the loss of genetic information and trigger DNA damage responses. Cultured mammalian cells have served as critical model systems for studying the function of telomere binding proteins and telom-erase. Tremendous heterogeneity can be observed both between species and within a single cell line population. Here, we describe the assay that analyzes the average length of telomeres in cultured cells (TRF analysis). Key words: Telomere length, TRF, Telomere maintenance In eukaryotic cells with linear chromosomes, the chromosomal ends – telomeres – are maintained and protected through the coordinated action of telomerase and telomere binding proteins (1, 2). Perturbations in this intricate telomere interacting network can lead to changes in telomere structure and exposed chromo-somal ends (3, 4). In telomerase active cells such as cancer cells and during development, such changes in turn impact on the length of telomeres and the status of the cell such as its replicative potential (5, 6). Different organisms display remarkable variability in the make-up and exact length of the repetitive telomeric elements in their telomere DNA sequences. For example, in yeast, the sequence is 350 ± 75 bp of C1–3A/TG1–3 (7), whereas mammalian telomeres contain (TTAGGG)n. Among mammalian species, mouse telomeres can be up to 150 kb, while somatic human cells have telomeres o