Project description:MCF7 and MDA-MB-231 breast cancer cell lines were cultured in DMEM-F12 containing 10% FBS (Lonza) 100U/ml penicillin and 100 µg/ml streptomycin (Lonza). Transfecting third generation packaging vectors using Poly-ethylenimine into HEK293T cells generated lentiviral particles (17). MCF7 and MDA-MB-231 cells were stably transduced with lentivirus containing pINDUCER20-FOXO3.A3, allowing doxycycline induced expression of constitutively active FOXO3 (FOXO3.A3). Cells were treated with 20% FBS or 10 µM PI3K inhibitor LY294002 (Selleckchem) for 16 hours to activate and inactivate the endogenous PI3K pathway, respectively. FOXO3.A3 expression was induced by 16 hours treatment with 10 ng/ml doxycycline.
Project description:Forkhead Box O (FOXO) transcription factors are versatile players in diverse cellular processes, affecting tumorigenesis, metabolism, stem cell maintenance and lifespan. To understand the transcriptional output of FOXO3 activation, we investigate features that define the subset of enhancer binding events that actually contribute to gene regulation. We show FOXO3 transcriptional output is determined by the amount of bound FOXO3, which in turn is determined by motif presence, pre-existing enhancer activity and accessibility. In this manner, FOXO3 amplifies pre-existing levels of activity marks and potentiates enhancer RNA transcription. We conclude that not only enhancer presence and sequence content, but also the pre-existing activity dictates FOXO3 binding and transcriptional output. Considering the flexible and cell type specific nature of regulatory regions and their activity, our observations provide a novel explanation for the diversity in FOXO transcriptional programs and introduce chromatin context as a new player in the regulation of FOXO activity in ageing and disease. Examination of histone modifications and transcriptome changes upon FOXO activation
Project description:Forkhead Box O (FOXO) transcription factors are versatile players in diverse cellular processes, affecting tumorigenesis, metabolism, stem cell maintenance and lifespan. To understand the transcriptional output of FOXO3 activation, we investigate features that define the subset of enhancer binding events that actually contribute to gene regulation. We show FOXO3 transcriptional output is determined by the amount of bound FOXO3, which in turn is determined by motif presence, pre-existing enhancer activity and accessibility. In this manner, FOXO3 amplifies pre-existing levels of activity marks and potentiates enhancer RNA transcription. We conclude that not only enhancer presence and sequence content, but also the pre-existing activity dictates FOXO3 binding and transcriptional output. Considering the flexible and cell type specific nature of regulatory regions and their activity, our observations provide a novel explanation for the diversity in FOXO transcriptional programs and introduce chromatin context as a new player in the regulation of FOXO activity in ageing and disease.
Project description:In the nervous system, neural stem cells (NSC) are necessary for the generation of new neurons and for cognitive function. Here we show that FoxO3, a member of a transcription factor family known to extend lifespan in invertebrates, regulates the NSC pool. We find that adult FoxO3-/- mice have fewer NSC in vivo than wild type counterparts. NSC isolated from adult FoxO3-/- mice have decreased self-renewal and an impaired ability to generate different neural lineages. Identification of the FoxO3-dependent gene expression profile in NSC suggests that FoxO3 regulates the NSC pool by inducing a program of genes that preserves quiescence, prevents premature differentiation, and controls oxygen metabolism. The ability of FoxO3 to prevent the premature depletion of NSC might have important implications for counteracting brain aging in long-lived species. Experiment Overall Design: mRNA expression from secondary neurospheres cultured from cells taken from mouse forebrains was compared between FoxO3+/+ (wildtype) and FoxO3-/- (null mutant) mice from the FVB/N background.
Project description:In the nervous system, neural stem cells (NSC) are necessary for the generation of new neurons and for cognitive function. Here we show that FoxO3, a member of a transcription factor family known to extend lifespan in invertebrates, regulates the NSC pool. We find that adult FoxO3-/- mice have fewer NSC in vivo than wild type counterparts. NSC isolated from adult FoxO3-/- mice have decreased self-renewal and an impaired ability to generate different neural lineages. Identification of the FoxO3-dependent gene expression profile in NSC suggests that FoxO3 regulates the NSC pool by inducing a program of genes that preserves quiescence, prevents premature differentiation, and controls oxygen metabolism. The ability of FoxO3 to prevent the premature depletion of NSC might have important implications for counteracting brain aging in long-lived species.
Project description:FOXO3 is an evolutionally conserved transcription factor that has been linked to longevity. Here we asked whether human stem cells could be functionally enhanced by engineering them to express an activated form of FOXO3. This was accomplished via HDAdV-mediated gene editing of human embryonic stem cells. These cells were then differentiated into a range of vascular cell types, as FOXO3 has been shown to play a protective role in the cardiovascular system. FOXO3-enhanced vascular cells exhibited delayed senescence and increased resistance to oxidative injuries, compared with wild type cells. When tested in a therapeutic context, FOXO3-enhanced human mesenchymal stem cells promoted vasculature regeneration in a mouse model of ischemic injury, and were resistant to tumorigenic transformation, both in vitro and in vivo. Mechanistically, constitutively active FOXO3 conferred cytoprotection by transcriptionally downregulating CSRP1. Taken together, our findings provide mechanistic insights into FOXO3-mediated vascular protection, and indicate that FOXO3 activation may provide a means for generating more effective and safe biomaterials for cell replacement therapies.
Project description:We showed that the transcription factor Foxo3 played a specific role in the polarization of CD4+ T cells towards pathogenic Th1 cells producing both interferon-γ (IFN-γ) and granulocyte monocyte colony stimulating factor (GM-CSF). To understand the molecular mechanisms whereby Foxo3 controls CD4+ T cell differentiation, unbiased analysis of genes differentially expressed in Foxo3-deficient vs. Foxo3-sufficient CD4+ T cells was achieved using both resting and activated CD4+ T cells obtained following 12 or 24 hours of stimulation with anti-CD3 mAbs.
Project description:Reduction-oxidation (redox) signaling, the translation of an oxidative intracellular environment into a cellular response, is mediated by the reversible oxidation of specific cysteine thiols. The latter results in disulfide formation between protein (hetero)dimers that alter protein function until the cellular redox has returned to the basal state. We have previously shown that this mechanism promotes the nuclear localization and activity of the FOXO4 transcription factor. Here, we present evidence that FOXO3 and FOXO4 have acquired paralog-specific cysteines throughout vertebrate evolution. Using a proteome-wide screen we identified previously unknown redox-dependent FOXO3 interaction partners. The nuclear import receptor IPO7 forms a disulfide-dependent heterodimer with FOXO3, but not with FOXO4, which is required for reactive oxygen species (ROS)-induced nuclear translocation . These findings suggest that evolutionary acquisition of cysteines has contributed to functional divergence of FOXO paralogs.