Keap1 controls protein S-nitrosation and apoptosis-senescence switch in endothelial cells

Abstract

Premature senescence, a death escaping pathway for cells experiencing stress, is conducive to aging and cardiovascular diseases. The molecular switch between senescent and apoptotic fate remains, however, poorly recognized. Nrf2 is an important transcription factor orchestrating adaptive response to cellular stress. Here, we show that both human primary endothelial cells (ECs) and murine aortas lacking Nrf2 signaling are senescent but unexpectedly do not encounter damaging oxidative stress. Instead, they exhibit markedly increased S-nitrosation of proteins. A functional role of S-nitrosation is protection of ECs from death by inhibition of NOX4-mediated oxidative damage and redirection of ECs to premature senescence. S-nitrosation and senescence are mediated by Keap1, a direct binding partner of Nrf2, which colocalizes and precipitates with nitric oxide synthase (NOS) and transnitrosating protein GAPDH in ECs devoid of Nrf2. We conclude that the overabundance of this “unrestrained” Keap1 determines the fate of ECs by regulation of S-nitrosation and propose that Keap1/GAPDH/NOS complex may serve as an enzymatic machinery for S-nitrosation in mammalian cells.

Simvastatin Attenuates Abdominal Aortic Aneurysm Formation Favoured by Lack of Nrf2 Transcriptional Activity

“…Although Nrf2 is a crucial regulator of cellular response to oxidative stress [4,5], the inhibition of its transcriptional activity did not lead to excessive cellular ROS production in our animal model. It stays in agreement with our previous data that in the aortas of Nrf2 tKO mice, there are no signs of oxidative damage, manifested by lipid peroxidation [24]. Here, we demonstrated that irrespective of the genotype, AngII infusion led to an increase in the ROS level, which was partially attenuated by simvastatin treatment.…”

“…This matches the previous observation that activation of Nrf2 can counteract AAA formation [5] and confirms that Nrf2 plays a role in the prevention of AAA development. Our group showed that the aortas of Nrf2 tKO mice undergo premature senescence [24], which could increase the susceptibility to aneurysm formation. In accordance, age-related decline in Nrf2 transcriptional activity in human correlates with the incidence of cardiovascular disorders, also AAA [5].…”

“…It could give us insights in AAA formation mechanisms and relate our previous findings to the impact on cardiovascular disorders. Aortas of Nrf2 transcriptional knockout mice undergo premature senescence, exhibit massive protein S-nitrosation [24], and enhanced protein aggregation [29] which could partially explain the higher susceptibility to AngII-induced AAA formation.…”

Bioactive Peptide F2d Isolated from Rice Residue Exerts Antioxidant Effects via Nrf2 Signaling Pathway

“…In order to further study the functional role of F2d on oxidative stress injury, we selected HUVEC induced by H 2 O 2 as the cell model and determined the expression levels of apoptosis-related proteins Bcl-2, Bax, and Caspase-3 to study the effect of F2d on apoptosis influences. The latest research reports showed that Keap1, a cytoplasmic inhibitory protein that regulated Nrf2, also played a very important role in antiapoptosis [ 36 ]. On the basis of this theory, first, we detected the apoptosis after F2d treatment by flow cytometry.…”

Contributions of Costimulatory Molecule CD137 in Endothelial Cells

“… 18 Nuclear factor erythroid 2‐related factor 2 regulates intracellular redox balance and extracellular oxidative stress in ECs. 24 Moreover, activation of CD137 signaling using agonist‐CD137 recombinant protein (CD137L) promotes endothelial apoptosis by modulating both nuclear factor erythroid 2‐related factor 2 and nuclear factor‐κB pathways. This subsequently induces the production of reactive oxygen species and increases the expression of proinflammatory cytokine genes, including interleukin‐6, IL‐1β, and tumor necrosis factor‐α.…”