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Up‐regulation of the interferon‐inducible IFI16 gene by oxidative stress triggers p53 transcriptional activity in endothelial cells
Author(s) -
Gugliesi Francesca,
Mondini Michele,
Ravera Raffaella,
Robotti Andrea,
Andrea Marco,
Gribaudo Giorgio,
Gariglio Marisa,
Landolfo Santo
Publication year - 2005
Publication title -
journal of leukocyte biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.819
H-Index - 191
eISSN - 1938-3673
pISSN - 0741-5400
DOI - 10.1189/jlb.0904507
Subject(s) - oxidative stress , biology , cycloheximide , reactive oxygen species , microbiology and biotechnology , biochemistry , protein biosynthesis
Reactive oxygen species (ROS), including hydrogen peroxide (H 2 O 2 ), induces injury of endothelium in a variety of pathophysiological conditions, such as inflammation, aging, and cancer. In our study, we characterized the signaling pathway linking oxidative stress induced by sublethal concentrations of H 2 O 2 to p53 in primary human endothelial cells through the interferon (IFN)‐inducible gene IFI16. Induction of IFI16 by H 2 O 2 was concentration‐ and time‐dependent (maximum at 50 μM, 6 h after treatment) and down‐regulated by pretreatment with N‐acetyl‐L‐cysteine, which acts as an antioxidant. This pathway is a general response to ROS and not specific to H 2 O 2 treatment, as two other ROS‐generating compounds, i.e., S‐nitroso‐N‐acetylpenicillamine and tert‐butyl hydroperoxide, were equally capable to induce IFI16. Moreover, IFI16 up‐regulation is a result of protein accumulation, as expression of corresponding mRNA, assessed by real‐time polymerase chain reaction, was not affected. To investigate the mechanism of IFI16 accumulation, cells were incubated for 6 h in the presence of H 2 O 2 or IFN‐β, and then cycloheximide was added to inhibit further protein synthesis. The half‐life of IFI16 protein was found to be significantly increased in H 2 O 2 ‐treated cells compared with IFN‐β‐treated cells (t1/2=120 min vs. >30 min in H 2 O 2 ‐ vs. IFN‐β‐treated cells, respectively). An increase of IFI16 was accompanied by interaction with p53 phosphorylated at its N terminus, as shown by immunoprecipitation experiments. Moreover, binding to IFI16 resulted in its transcriptional activation as shown by an increase in the activity of a reporter gene driven by p53‐responsive sequences derived from the p21 WAF1 promoter, along with an increase in the p21 mRNA and protein levels. Altogether, these results demonstrate a novel role of IFI16 in the signal transduction pathway that leads to p53 activation by oxidative stress in endothelial cells.