Project description:To identify genes regulated by FOXO1, we performed RNA-seq analysis of human unbilical vein endothelial cells (HUVECs) overexpressing CA-FOXO1 by adenovirus. CA-FOXO1 is constructed by mutating three amino-acids phosphorylated by Akt, T24, S256, and S319, and is constitutively localized in the nucleus compared to wild-type FOXO1.
Project description:ChIP-Seq profiling of human umbilical vein endothelial cells (HUVECs) overexpressing constitutively active FOXO1 to identify FOXO1 DNA binding sites and to assess changes in the histone modifications H3K4me3 and H3K27ac.
Project description:Analysis of transcriptional changes upon silencing of endothelial VEGF. Because transcription factor Foxo1 levels increase under VEGF silencing, we hypothesized that Foxo1 transcriptional activity would be apparent in a whole-genome microarray. Double-silencing of VEGF+Foxo1 was also performed to determine which transcriptional changes are Foxo1-dependent in a VEGF-deficient background.
Project description:One major effect of PI3-kinase activation downstream of the serine/threonine kinase Akt is the phosphorylation of the transcription factor FOXO1 and its neutralization. FOXO1 has several ubiquitous targets genes in many cell types that control cell quiescence, oxydative stress or apoptosis. However, it has been demonstrated that FOXO1 also has specific targets depending of the cellular context. The role of FOXO1 to regulate specific genes in T lymphocytes has not been investigated yet. To examine this point, we used the CD4+ leukemia Jurkat T-cell line, in which the PI3K pathway is constitutively turned-on and FOXO1 transcriptional activity strongly repressed. These cells were transduced with lentiviruses coding for a constitutively active form of FOXO1 fused to GFP and having the three AKT phosphorylation sites mutated to alanine (FOXO1-AAA-GFP) to restore its transcriptional activity. GFP-transduced cells were used as a control and the gene activation levels in the two cell populations analyzed 48 hours post-infection.
Project description:Regulatory T (Treg) cells characterized by expression of the transcription factor forkhead box P3 (Foxp3) maintain immune homeostasis by suppressing self-destructive immune responses1-4. Foxp3 operates as a late acting differentiation factor controlling Treg cell homeostasis and function5, whereas the early Treg cell lineage commitment is regulated by the Akt kinase and the forkhead box O (Foxo) family of transcription factors6-10. However, whether Foxo proteins act beyond the Treg cell commitment stage to control Treg cell homeostasis and function remains largely unexplored. Here we show that Foxo1 is a pivotal regulator of Treg cell function. Treg cells express high amounts of Foxo1, and display reduced T-cell receptor-induced Akt activation, Foxo1 phosphorylation, and Foxo1 nuclear exclusion. Mice with Treg cell-specific deletion of Foxo1 develop a fatal inflammatory disorder similar in severity to Foxp3-deficient mice, but without the loss of Treg cells. Genome-wide analysis of Foxo1 binding sites reveals ~300 Foxo1-bound target genes, including the proinflammatory cytokine Ifng, that do not appear to be directly regulated by Foxp3. These findings demonstrate that the evolutionarily ancient Akt-Foxo1 signaling module controls a novel genetic program indispensable for Treg cell function. Regulatory T cells were FACS sorted in WT mice (2 reps), Foxo1 KO mice (2 reps), mice expressing a constitutively active form of Foxo1 (1 rep), and Foxo1 KO mice expressing constitutively active Foxo1. We identified genes differentially expressed in WT vs. KO mice and assessed whether expression was recovered in the KO in presence of constitutively active Foxo1
Project description:Adenoviral expression of a constitutive active FOXO1 vs. control GFP in human umbilical vein endothelial cells (HUVEC). Expression analysis 16 h after transduction.