PARP 1 inhibition mediates a switch from cell death to transient senescence improving repair from acute oxidative injury
Ontology highlight
ABSTRACT: Excessive amounts of Reactive Oxygen Species (ROS) lead to macromolecular damage and high levels of cell death and pathological sequelae. Switching cell death to a tissue regenerativestate can potentially improve short – and long-term consequences of ROS-associated acute tissueinjury. However, the mechanisms regulating oxidative stress-induced cell fate decision and their manipulation for improving repair remain poorly understood. Here, we show that cells exposed tohigh oxidative stress enter a PARP1-mediated regulated cell death, and that blocking PARP1activation promotes conversion of cell death into senescence (CODIS). We demonstrate that CODIS depends on reducing mitochondrial Ca2+ overload as a consequence of retaining thehexokinase HKII onto mitochondria. In a mouse model of kidney ischemia/reperfusion damage,PARP1 inhibition lowers necrosis and increases acute and transient senescence at the injury site,leading to improved recovery from damage. For the first time, we provide evidence that strategiesconverting cell death into acute senescence can therapeutically reduce the detriment of accidental tissue damage. _x000B_
Project description:Altered oncogene expression in cancer cells causes loss of redox homeostasis resulting in oxidative DNA damage, e.g., 8-oxoguanine (8-oxoG), repaired by base excision repair (BER). PARP1 coordinates BER and relies on the upstream 8-oxoguanine-DNA glycosylase (OGG1) to recognise and excise 8-oxoG. Here we hypothesize that OGG1 may represent an attractive target to exploit reactive oxygen species (ROS) elevation in cancer. Although OGG1 depletion is well tolerated in non-transformed cells, we report here that OGG1 depletion obstructs A3 T-cell lymphoblastic acute leukemia growth in vitro and in vivo, validating OGG1 as a potential anti- cancer target. In line with this hypothesis, we show that OGG1 inhibitors (OGG1i) target a wide range of cancer cells, with a favourable therapeutic index compared to non-transformed cells. Mechanistically, OGG1i and shRNA depletion cause lost mitochondrial function leading to S- phase DNA damage, replication stress and proliferation arrest or cell death, representing a novel mechanistic approach to target cancer. This study adds OGG1 to the list of BER factors, e.g., PARP1, as potential targets for cancer treatment. _x000B_
Project description:Excessive levels of reactive oxygen species (ROS) cause cellular stress through damage to all classes of macromolecules and result in cell death. However, ROS can also act as signaling molecules in various biological processes. In plants, ROS signaling has been documented in environmental stress perception, plant development and cell death amongst others. Knowledge on the regulatory events governing ROS signal transduction is however still scratching the surface. To further elucidate the transcriptional response and regulation upon ROS accumulation we supplemented Arabidopsis seedlings with a 10mM hydrogen peroxide (H2O2) solution to trigger oxidative stress.
Project description:ABSTRACT Rationale Premature senescence is conducive to aging and cardiovascular diseases. Nrf2 transcription factor, the master orchestrator of adoptive response to cellular stress, has been implicated in regulation of premature senescence in fibroblasts, neural and mesenchymal stem cells by transactivation of antioxidant gene expression. However, as we show here, human primary endothelial cells (ECs) devoid of Nrf2 and murine Nrf2 transcriptional knockout (tKO) aortas are senescent but do not encounter oxidative stress and damage, what contradicts this mechanism. Moreover, a molecular switch between normal, senescent and apoptotic fate remains unknown. Objective To elucidate the mechanism of Nrf2-related premature senescence of vascular system, to understand why Nrf2 deregulation does not cause oxidative stress exclusionary in ECs and to indicate a molecular switch determining ECs fate. Methods and Results Herein we evidence that ECs deficient in Nrf2 protein, or with limited Nrf2 activity in shear stress conditions, exhibit excessive S-nitrosylation of proteins. It is also a characteristic of Nrf2 tKO murine aortas, as determined by biotin switch assay in situ. Mass spectrometry analysis reveals that NOX4 is S-nitrosylated exclusively in ECs devoid of Nrf2. A functional role of S-nitrosylation is protection of ECs from death by inhibition of NOX4-mediated oxidative damage. As a result Nrf2-deficient ECs preserve oxidative balance but are redirected to premature senescence. The same phenotype is seen in Nrf2 tKO aortas. These effects are mediated by Keap1, a direct binding partner of Nrf2 and repressor of its transcriptional activity, remaining in cytoplasm unrestrained by Nrf2. S-nitrosylation, followed by senescence, can also be triggered in smooth muscle cells (SMCs) by EC-derived paracrine induction of iNOS. Conclusions Collectively, Keap1-dependent S-nitrosylation of NOX4 hampers oxidative detriment in ECs with disturbed Nrf2 signaling and may provide defence in the adjacent aortic cells. Overabundance of unrestrained Keap1 in the cytoplasm determines fate of ECs.
Project description:Excessive levels of reactive oxygen species (ROS) cause cellular stress through damage to all classes of macromolecules and result in cell death. However, ROS can also act as signaling molecules in various biological processes. In plants, ROS signaling has been documented in environmental stress perception, plant development and cell death amongst others. Knowledge on the regulatory events governing ROS signal transduction is however still scratching the surface. To further elucidate the transcriptional response and regulation upon ROS accumulation we supplemented Arabidopsis seedlings with a 10mM hydrogen peroxide (H2O2) solution to trigger oxidative stress. After growth of 7 days, hydrogen peroxide (H2O2) was added to a final concentration of 10mM. Control plants were treated with the same volume of H2O. Seedlings were grown for 24h under the same controlled conditions. Design: 3 replicates x 2 conditions (7+1 day H2O or 7+1 day H2O2)
Project description:Senescent cells secrete many molecules, which contribute to the prevention of cancer progression. We induced MSC senescence by oxidative stress, DNA damage, and replicative exhaustion. The first two are considered inducers of acute senescence while extensive proliferation triggers replicative senescence also named chronic senescence. We cultivated cancer cells in the presence of acute and chronic senescent MSC conditioned media and evaluated proliferation, DNA damage, apoptosis and senescence.
Project description:PML nuclear bodies (NBs) recruit partner proteins -including p53 and its regulators- controlling their abundance or function. Investigating arsenic sensitivity of acute promyelocytic leukemia, we proposed that PML oxidation promotes NB-biogenesis. Yet, physiological links between PML and oxidative stress response in vivo remain unexplored. Here we identify PML as a reactive oxygen species (ROS) sensor. Pml-/- cells accumulate ROS, while PML expression decreases ROS levels. Unexpectedly, Pml-/- embryos survive acute glutathione depletion. Moreover, Pml-/- animals are resistant to acetaminophen hepatotoxicity or fasting-induced steatosis. Molecularly, Pml-/- animals fail to properly activate oxidative stress-responsive p53 targets, while NRF2 response is accelerated. Finally, in an oxidative stress-prone background, Pml-/- animals display a longevity phenotype, likely reflecting decreased basal p53 activation. Thus, similar to p53, PML exerts basal anti-oxidant properties, but also drives oxidative stress-induced changes in cell survival/proliferation or metabolism in vivo. Through NB-biogenesis, PML therefore couples ROS-sensing to p53 responses, shedding a new light on PML role in senescence or stem cell biology.
Project description:Reactive oxygen species (ROS) are extensively assessed in physiological and pathological studies; however, the genes and mechanisms involved in antioxidant reactions are elusive. To address this knowledge gap, we used a forward genetic approach with mouse haploid embryonic stem cells (haESCs) to generate high-throughput mutant libraries, from which numerous oxidative stress-targeting genes were screened out. We performed proof-of-concept experiments to validate the potential inserted genes. Slc25a43 (one of the candidates) knockout (KO) ESCs presented reduced damage caused by ROS and higher cell viability when exposed to H2O2. Subsequently, ROS production and mitochondrial function analysis also confirmed that Slc25a43 was a main target gene of oxidative toxicity. In addition, we identified that KO of Slc25a43 activated mitochondria-related genes including Nlrx1 to protect ESCs from oxidative damage. Overall, our findings facilitated revealing target genes of oxidative stress and shed lights on the mechanism underlying oxidative death.
Project description:One of the most critical axes for cell fate determination is how cells respond to excessive reactive oxygen species (ROS)-oxidative stress. Extensive lipid peroxidation commits cells to death via a distinct cell death paradigm termed ferroptosis. However, the molecular mechanism regulating cellular fates to distinct ROS remains incompletely understood. Through siRNA against human receptor-interacting protein kinases (RIPK) family members, we discovered that RIPK4 is crucial for oxidative stress and ferroptotic death. Upon ROS induction, RIPK4 is rapidly activated and the kinase activity of RIPK4 is indispensable to induce cell death. Specific ablation of RIPK4 in kidney proximal tubules protects mice from acute kidney injury induced by cisplatin and renal ischemia/reperfusion. RNA sequencing revealed the dramatically decreased expression of acyl-CoA synthetase medium-chain (ACSM) family members induced by cisplatin treatment which is compromised in RIPK4 deficient mice. Among these ACSM family members, suppression of ACSM1 strongly augments oxidative stress and ferroptotic cell death with induced expression of ACSL4, an important component for ferroptosis execution. Our lipidome analysis revealed that over-expression of ACSM1 leads to the accumulation of monounsaturated fatty acids (MUFAs), attenuation of polyunsaturated fatty acids (PUFAs) production, and thereby cellular resistance to ferroptosis. Hence, knock-down ACSM1 re-sensitizes RIPK4 KO cells to oxidative stress and ferroptotic death. In conclusion, RIPK4 is a key player involved in oxidative stress and ferroptotic death, which is potentially important for a broad spectrum of human pathologies. The link between RIPK4-ASCM1 axis to PUFAs and ferroptosis reveals a novel mechanism to oxidative stress induced necrosis and ferroptosis.
Project description:DallePazze2014 - Cellular senescene-induced
mitochondrial dysfunction
This model is described in the article:
Dynamic modelling of
pathways to cellular senescence reveals strategies for targeted
interventions.
Dalle Pezze P, Nelson G, Otten EG,
Korolchuk VI, Kirkwood TB, von Zglinicki T, Shanley DP.
PLoS Comput. Biol. 2014 Aug; 10(8):
e1003728
Abstract:
Cellular senescence, a state of irreversible cell cycle
arrest, is thought to help protect an organism from cancer, yet
also contributes to ageing. The changes which occur in
senescence are controlled by networks of multiple signalling
and feedback pathways at the cellular level, and the interplay
between these is difficult to predict and understand. To
unravel the intrinsic challenges of understanding such a highly
networked system, we have taken a systems biology approach to
cellular senescence. We report a detailed analysis of
senescence signalling via DNA damage, insulin-TOR, FoxO3a
transcription factors, oxidative stress response, mitochondrial
regulation and mitophagy. We show in silico and in vitro that
inhibition of reactive oxygen species can prevent loss of
mitochondrial membrane potential, whilst inhibition of mTOR
shows a partial rescue of mitochondrial mass changes during
establishment of senescence. Dual inhibition of ROS and mTOR in
vitro confirmed computational model predictions that it was
possible to further reduce senescence-induced mitochondrial
dysfunction and DNA double-strand breaks. However, these
interventions were unable to abrogate the senescence-induced
mitochondrial dysfunction completely, and we identified
decreased mitochondrial fission as the potential driving force
for increased mitochondrial mass via prevention of mitophagy.
Dynamic sensitivity analysis of the model showed the network
stabilised at a new late state of cellular senescence. This was
characterised by poor network sensitivity, high signalling
noise, low cellular energy, high inflammation and permanent
cell cycle arrest suggesting an unsatisfactory outcome for
treatments aiming to delay or reverse cellular senescence at
late time points. Combinatorial targeted interventions are
therefore possible for intervening in the cellular pathway to
senescence, but in the cases identified here, are only capable
of delaying senescence onset.
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Project description:Oxidative modifications can disrupt protein folds and functions, and are strongly associated with human aging and diseases. Conventional oxidation pathways typically involve the free diffusion of reactive oxygen species (ROS), which primarily attack the protein surface. Yet, it remains unclear whether and how internal protein folds capable of trapping oxygen (O2) contribute to oxidative damage. Here, we report a novel pathway of protein damage, which we refer to asO2-confined photooxidation. In this process, O2 is captured in protein cavities and subsequently converted into multiple ROS, primarily mediated by tryptophan residues under blue light irradiation. The generated ROS then attack the protein interior through constrained diffusion, causing protein damage. The effects of this photooxidative reaction appear to be extensive, impacting a wide range of cellular proteins,as supported by whole-cell proteomic analysis. This photooxidative mechanism may represent a latent oxidationpathway in human tissuesdirectly exposed to visible light, such as skin and eyes.