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γ‐H2AX Formation is not Coupled to Elevations in Intracellular Ca 2+ , and Hyperactivation of PARP does not Facilitate AIF Translocation During ROS‐induced Cell Death.
Author(s) -
XIE Ruiyu,
Lau Serrine S,
Monks Terrence J
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.1140.4
Subject(s) - poly adp ribose polymerase , programmed cell death , nad+ kinase , intracellular , mitochondrion , reactive oxygen species , hyperactivation , chemistry , apoptosis , dna damage , microbiology and biotechnology , mitochondrial ros , chromosomal translocation , apoptosis inducing factor , biology , biochemistry , dna , caspase , polymerase , enzyme , gene
2,3,5‐tris(Glutathion‐S‐yl)hydroquinone (TGHQ) is a redox‐active metabolite of hydroquinone, and causes non‐apoptotic cell death in renal proximal tubule epithelial cells (HK‐2) via the generation of reactive oxygen species (ROS). TGHQ induced ROS generation and DNA strand breaks leads to the overactivation of poly(ADP‐ribose) polymerase‐1 (PARP‐1), the rapid depletion of nicotinamide adenine dinucleotide (NAD + ), and the appearance of γ‐H2AX foci. Inhibition of PARP‐1 completely blocked TGHQ‐mediated poly(ADP‐ribosyl)ation (PAR), NAD + consumption, and the consequent necrotic cell death. Moreover, although Ca 2+ chelation inhibited PAR and significantly abrogated cell death, NAD + depletion was only delayed and not prevented. Despite their ability to inhibit cell death, neither PARP inhibition nor Ca 2+ chelation altered ROS production or the initial DNA damage (γ‐H2AX foci). Interestingly, PARP‐1 hyperactivation was not accompanied by the translocation of apoptosis‐inducing factor (AIF) from mitochondria to the nucleus, a process usually associated with PARP‐dependent cell death. In conclusion, PARP activation and Ca 2+ elevation are critical responses to ROS‐mediated cell death, but at least in HK‐2 cells γ‐H2AX formation is not coupled to elevations in intracellular Ca 2+ , and PARP activation does not facilitate AIF translocation. (DK59491, P30 ES 06694).