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The TUNEL Assay

Overview

One of the hallmarks of apoptosis is the nuclear DNA fragmentation by nucleases. These enzymes are activated by caspases, the family of proteins that execute the cell death program. TUNEL assay is a method that takes advantage of this feature to detect apoptotic cells. In this assay, an enzyme called terminal deoxynucleotidyl transferase catalyzes the addition of dUTP nucleotides to the free 3’ ends of fragmented DNA. By using dUTPs that are labeled with chemical tags that can produce fluorescence or color, apoptotic cells can be specifically identified.

JoVE’s video on the TUNEL assay begins by discussing how this technique can be used to detect apoptotic cells. We then go through a general protocol for performing TUNEL assays on tissue sections and visualizing the results using fluorescence microscopy. Finally, several applications of the assay to current research will be covered.

Procedure

The TUNEL assay is most commonly used to detect cells undergoing apoptosis, which is a form of programmed cell death. Apoptosis is an important biological process during development, and for maintaining tissue homeostasis. TUNEL staining allows for visualization and quantification of apoptotic cells. This helps scientists test efficacy of new treatments for disorders in which apoptosis is either inhibited, like in cancer, or enhanced, as in neurodegeneration.

This video will explain how the TUNEL assay can be used to

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Tags
TUNEL AssayApoptosisProgrammed Cell DeathBiological ProcessTissue HomeostasisTUNEL StainingNew TreatmentsDisordersCancerNeurodegenerationCell Death MechanismsDNA FragmentationCaspasesCaspase activated DNase CADEndonucleaseChromosomal DNA CleavageFragmented DNA Detection

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0:00

Overview

0:59

Principles of the TUNEL Assay

3:06

Generalized TUNEL Assay Protocol in Tissue Sections

5:34

Applications

7:35

Summary

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