TUNEL Assay: A Powerful Tool for Kidney Injury Evaluation

Abstract

Terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay is a long-established assay used to detect cell death-associated DNA fragmentation (3’-OH DNA termini) by endonucleases. Because these enzymes are particularly active in the kidney, TUNEL is widely used to identify and quantify DNA fragmentation and cell death in cultured kidney cells and animal and human kidneys resulting from toxic or hypoxic injury. The early characterization of TUNEL as an apoptotic assay has led to numerous misinterpretations of the mechanisms of kidney cell injury. Nevertheless, TUNEL is becoming increasingly popular for kidney injury assessment because it can be used universally in cultured and tissue cells and for all mechanisms of cell death. Furthermore, it is sensitive, accurate, quantitative, easily linked to particular cells or tissue compartments, and can be combined with immunohistochemistry to allow reliable identification of cell types or likely mechanisms of cell death. Traditionally, TUNEL analysis has been limited to the presence or absence of a TUNEL signal. However, additional information on the mechanism of cell death can be obtained from the analysis of TUNEL patterns.

Single cell RNA-seq analysis identifies ferroptotic chondrocyte cluster and reveals TRPV1 as an anti-ferroptotic target in osteoarthritis

“…Furthermore, CPS exerted similar anti-ferroptotic effect to Fer-1 by mitigating the TBHP-induced 4-HNE and COX2 expression and restoring FTH1 ( Figure 5 i, Supplementary Figure 11b). Then, we used Tunel assay to detect cell death 47 and revealed significantly reduced Tunel + chondrocytes in the TBHP with CPS or Fer-1 treated groups ( Figure 5 j, Supplementary Figure 11c). Taken together, these results indicate that TRPV1 exerts anti-ferroptotic and chondroprotective effects in both DMM-induced mice cartilage and human OA cartilage.…”

Marked to Die-Cell Death Mechanisms for Keratinocyte Acantholysis in Pemphigus Diseases

“…The TUNEL assay allows the identification of endonuclease-driven DNA fragmentation (causing 3′-OH DNA termini), associated with different mechanisms of cell death, including but not restricted to apoptosis [ 137 ]. TUNEL+ cells were reported in 17 PV biopsies [ 105 ], in perilesional biopsies of 23 PV and 13 PF patients [ 107 ], in the lesional and perilesional epidermis and dermis of 5 PV patients [ 80 ], as well as in the epithelium (12/13) and inflammatory exudate (11/13) in Brazilian EPF patients [ 65 ] ( Table 3 ).…”

Induction of ferroptosis selectively eliminates senescent tubular cells

“…Cell survival of senescent PTEC was effectively rescued by the ferroptosis‐inhibitor ferrostatin‐1 (Fer‐1) (Figure 1B). TUNEL, a universal assay for irreversible cell death including ferroptosis, 32 confirmed significantly increased cell death in RSL3‐treated senescent PTEC (Figure 1C). Successful blockade of cell death by co‐administration of Fer‐1 supported the role of ferroptosis in the observed cellular elimination (Figure 1C).…”