Amplification and Quantitation of Telomeric Extrachromosomal Circles

Area of Science:

• Genetics
• Molecular Biology
• Cell Biology

Background:

• Telomeres protect chromosome ends and dictate cellular lifespan.
• The alternative lengthening of telomeres (ALT) pathway elongates telomeres in stem and cancer cells.
• C-circles, extrachromosomal DNA, are hallmark markers of ALT activity.

Purpose of the Study:

• To develop a robust and generalizable assay for quantifying C-circles in mammalian cells.
• To establish a reliable method for determining telomere maintenance mechanisms (TMMs).
• To provide a tool for assessing ALT pathway activity under various experimental conditions.

Main Methods:

• Adaptation of the Quick C-circle Preparation (QCP) method for DNA isolation.
• Fluorometry-based DNA quantification and rolling circle amplification (RCA).
• Quantitative PCR (qPCR) for C-circle detection, including internal standards for benchmarking.

Main Results:

• The developed assay enables accurate quantitation of C-circle abundance.
• The protocol allows for reliable benchmarking of cells with unknown TMM status.
• The assay is suitable for mammalian cells undergoing diverse experimental manipulations.

Conclusions:

• C-circles are sensitive and specific markers of the ALT pathway.
• This C-circle assay provides a generalizable workflow for TMM ascertainment.
• The method facilitates research into telomere biology and cancer mechanisms.