We have developed a novel method that enables global subtelomere and haplotype-resolved analysis of telomere lengths at the single-molecule level. An in vitro CRISPR/Cas9 RNA-directed nickase system directs the specific labeling of human (TTAGGG) n DNA tracts in genomes that have also been barcoded using a separate nickase enzyme that recognizes a 7bp motif genome-wide. High-throughput imaging and analysis of large DNA single molecules from genomes labeled in this fashion using a nanochannel array system permits mapping through subtelomere repeat element (SRE) regions to unique chromosomal DNA while simultaneously measuring the (TTAGGG) n tract length at the end of each large telomere- terminal DNA segment. The methodology also permits subtelomere and haplotype-resolved analyses of SRE organization and variation, providing a window into the population dynamics and potential functions of these complex and structurally variant telomere-adjacent DNA regions. At its current stage of development, the assay can be used to identify and characterize telomere length distributions of 30-35 discrete telomeres simultaneously and accurately. The assay's utility is demonstrated using early versus late passage and senescent human diploid fibroblasts, documenting the anticipated telomere attrition on a global telomere-by-telomere basis as well as identifying subtelomere-specific biases for critically short telomeres. Similarly, we present the first global single-telomere-resolved analyses of two cancer cell lines.
Original Publication Citation
McCaffrey, J., Young, E., Lassahn, K., Sibert, J., Pastor, S., Riethman, H., & Xiao, M. (2017). High-throughput single-molecule telomere characterization. Genome Research. doi:http://dx.doi.org/10.1101/gr.222422.117
McCaffrey, Jennifer; Young, Eleanor; Lassahn, Katy; Sibert, Justin; Pastor, Steven; Riethman, Harold; and Xiao, Ming, "High-Throughput Single-Molecule Telomere Characterization" (2017). Medical Diagnostics & Translational Sciences Faculty Publications. 34.