High-throughput telomere length measurement at nucleotide resolution using the PacBio high fidelity sequencing platform

There exist challenges in quantifying the length of individual telomeres at single nucleotide resolution. Here the authors report a method to capture telomeres and accurately analyse their length in human cell lines and patient peripheral blood leukocyte samples using single-molecule real-time sequencing. Telomeres are specialized nucleoprotein structures at the ends of linear chromosomes. The progressive shortening of steady-state telomere length in normal human somatic cells is a promising biomarker for age-associated diseases. However, there remain substantial challenges in quantifying telomere length due to the lack of high-throughput method with nucleotide resolution for individual telomere. Here, we describe a workflow to capture telomeres using newly designed telobaits in human culture cell lines as well as clinical patient samples and measure their length accurately at nucleotide resolution using single-molecule real-time (SMRT) sequencing. Our results also reveal the extreme heterogeneity of telomeric variant sequences (TVSs) that are dispersed throughout the telomere repeat region. The presence of TVSs disrupts the continuity of the canonical (5'-TTAGGG-3')n telomere repeats, which affects the binding of shelterin complexes at the chromosomal ends and telomere protection. These findings may have profound implications in human aging and diseases.

Automated summary

The authors developed a method using single-molecule real-time (SMRT) sequencing to capture and accurately analyze the length of telomeres, addressing challenges in quantifying telomere length at the nucleotide level. Telomeres are specialized nucleoprotein structures at the ends of linear chromosomes, and their progressive shortening is a promising biomarker for age-associated diseases. The workflow involved capturing telomeres using new telobaits and measuring their length accurately with high resolution using SMRT sequencing. Results showed the heterogeneity of telomeric variant sequences (TVSs), which disrupt the continuity of the canonical telomere repeats and affect telomere protection.