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:The Pml gene is essential to the formation of PML nuclear bodies, domains which have been associated with various functions such as apoptosis/senescence, DNA repair and cell proliferation( Lallemand-Breitenbach 2010). PML-NBs formation is regulated by cellular stress including oxidative stress(Jeanne 2010, de The 2012). To investigate the role of PML in ROS response in vivo, we analyse the expression difference to the acetaminophen toxicity, which is initiated by ROS, in Pml wt and Pml KO mice.
Project description:The Pml gene is essential to the formation of PML nuclear bodies, domains which have been associated with various functions such as apoptosis/senescence, DNA repair and cell proliferation( Lallemand-Breitenbach 2010). PML-NBs formation is regulated by cellular stress including oxidative stress(Jeanne 2010, de The 2012). To investigate the role of PML in ROS response in vivo, we analyse the expression difference betweem Pml wt and Pml KO under fasted condition, which easily up-regulate ROS in BALB/cByJ background
Project description:The human pathogenic fungus Aspergillus fumigatus is readily eradicated by the innate immunity of immunocompetent human hosts, but can cause severe infections, such as invasive aspergillosis (IA), in immunocompromised individuals. During infection, the fungal redox homeostasis can be challenged by reactive oxygen (ROS) species, either derived from the oxidative burst of innate immune cells or the action of antifungal drugs. The peroxiredoxin Asp f3 was found to be essential to cause IA in mice, but how Asp f3 integrates to fungal redox homeostasis remains unknown. Here, we show that in vivo, Asp f3 acts as a sensor for ROS. While global transcription in fungal hyphae under minimal growth conditions was fully independent of Asp f3, a robust induction of the oxidative stress response required the presence of the peroxiredoxin. Hyphae devoid of Aspf 3 failed to activate several redox active genes, like members of the gliotoxin biosynthesis gene cluster and integral members of the Afyap1 regulon, the central activator of the ROS defence machinery in fungi. Upon deletion of the asp f3 gene Afyap1 displayed significantly reduced nuclear localization during ROS exposure, indicating that Asp f3 can act as an intracellular redox sensor for several target proteins
Project description:Acute myeloid leukemia (AML) pathogenesis often involves a mutation in the NPM1 nucleolar chaperone, but the bases for its transforming properties and association with favorable outcome remain incompletely understood. Here we demonstrate that an oncogenic mutant form of NPM1 (NPM1c) hampers formation of PML nuclear bodies (NBs), key senescence effectors, and impairs mitochondrial function to drive an integrated stress response. Actinomycin D (ActD), an antibiotic with unambiguous clinical efficacy in relapsed/refractory NPM1c-AMLs, preferentially targets these primed mitochondria, activating cGAS signaling and boosting ROS production. The later restores PML NB formation to drive senescence of NPM1c-AMLs cells. Dual targeting of mitochondria by Venetoclax and ActD synergized for AML elimination. Our studies reveal a central role of mitochondria downstream of NPM1c and implicate a mitochondrial/ROS/PML/TP53 senescence pathway as a key effector of ActD-based, and possibly others, chemotherapies.
Project description:Integrated-systems model of oxidative stress connecting NRF2 and p53 signaling pathways. Additional crosstalk linking oxidative stress to p53 inhibition, p53 to NRF2 through p21, and NRF2 to MDM2 was incorporated in this model. The NRF2 pathway was encoded as first- and second-order rate equations for KEAP1 oxidation and NRF2 stabilization; NRF2-mediated transcription of antioxidant enzymes was modeled as a Hill function. The p53 pathway was reconstructed from a delay differential equation model of p53 signaling in response to DNA damage. To adapt the p53 DNA-damage model to respond to oxidative stress, we used a first-order oxidation reaction of ATM/CHEK2 by intracellular H2O2.
The integrated base model of NRF2–p53 oxidative-stress signaling contains 42 reactions and 22 ordinary differential equations (ODEs).
Project description:Membrane-less organelles are condensates formed by phase separation whose functions often remain enigmatic. Upon oxidative stress, PML scaffolds Nuclear Bodies (NBs) to regulate senescence or metabolic adaptation, but their role in pluripotency remains elusive. Here we establish that PML is required for basal SUMO2/3 conjugation in mESCs and oxidative stress-driven sumoylation in mESCs or in vivo. PML NBs create an oxidationprotective environment for UBC9-driven SUMO2/3 conjugation of PML partners, often followed by their poly-ubiquitination and degradation. Differential in vivo proteomics identified several members of the KAP1 complex as PML NB-dependent SUMO2-targets. The latter drives functional activation of this key epigenetic repressor. Accordingly, Pml-/- mESCs reexpress transposable elements and display features of totipotent-like cells, a process further enforced by PML-controlled SUMO2-conjugation of DPPA2. Finally, PML is required for adaptive stress responses in mESCs. Collectively, PML orchestrates mESC fate through SUMO2-conjugation of key transcriptional or epigenetic regulators, raising new mechanistic hypotheses about PML roles in normal or cancer stem cells.
Project description:Membrane-less organelles are condensates formed by phase separation whose functions often remain enigmatic. Upon oxidative stress, PML scaffolds Nuclear Bodies (NBs) to regulate senescence or metabolic adaptation, but their role in pluripotency remains elusive. Here we establish that PML is required for basal SUMO2/3 conjugation in mESCs and oxidative stress-driven sumoylation in mESCs or in vivo. PML NBs create an oxidationprotective environment for UBC9-driven SUMO2/3 conjugation of PML partners, often followed by their poly-ubiquitination and degradation. Differential in vivo proteomics identified several members of the KAP1 complex as PML NB-dependent SUMO2-targets. The latter drives functional activation of this key epigenetic repressor. Accordingly, Pml-/- mESCs reexpress transposable elements and display features of totipotent-like cells, a process further enforced by PML-controlled SUMO2-conjugation of DPPA2. Finally, PML is required for adaptive stress responses in mESCs. Collectively, PML orchestrates mESC fate through SUMO2-conjugation of key transcriptional or epigenetic regulators, raising new mechanistic hypotheses about PML roles in normal or cancer stem cells.