AAT Bioquest and Late-Stage Apoptosis DNA Fragmentation Detection Via TUNEL
In1992, Gorczyca et al. introduced a new method of measuring apoptotic DNA fragmentation utilizing terminal deoxynucleotidyl transferase (TdT) and nick translation, known as the TUNEL assay. TdT catalyzes the addition of a fluorophore-labeled deoxyuridine triphosphate (dUTP) to the 3′-hydroxyl termni of a DNA double strand break (DSB).
Since the introduction of the TUNEL assay, it has become a widely-accepted in situ technique for identifying apoptotic cell death. Compared to previous methods, the TUNEL assay is more sensitive with the capacity to give a broad range of quantitative measurements over several orders of magnitude.
Several variables influence the staining kinetics of TUNEL assays. Some of these variables include reagent concentration, fixation of sample, and accessibility of DNA strand breaks, which may vary between tissue or cell sample types. Therefore, standardizing your chosen TUNEL assay and having appropriate controls are critical in data collection and interpretation.
Image: Apoptotic PCa cells in BM defined by TUNEL staining. PCa cells were recognized by pan cytokeratin with green color, and TUNEL signals were shown with red color. Nuclei stained with DAPI. Scale bar, 20 μm.