Which assays can be used for detecting DNA fragmentation resulting from programmed cell death (apoptosis)?
The biochemical hallmark of apoptosis is internucleosomal DNA cleavage into oligonucleosome-length fragments. Measurement of apoptosis-associated internucleosomal DNA fragmentation through determination of the percentage of fragmented DNA by electrophoresis or centrifugation of whole cell lysates is by far the most common means of quantifying apoptosis. DNA fragmentation due to apoptosis can also be identified using terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling of DNA fragments (TUNEL), in situ end labeling (ISEL) of the genomic DNA in fragmented nuclei, and measurement of cytosolic histone-bound DNA fragments (cell death ELISA assays).