Project description:The Prep1 (Pknox1) homeodomain transcription factor is essential at multiple stages of embryo development. In the E11.5 embryo trunk, we previously estimated that Prep1 binds about 3,300 genomic sites at a highly specific decameric consensus sequence, mainly governing basal cellular functions. We now show that in embryonic stem (ES) cells Prep1 binding pattern only partly overlaps that of the embryo trunk, with about 2,000 novel sites, highlighting a change of targets between embryonic differentiated v. embryonic stem cells. RNA-seq identifies about 1800 genes down-regulated in Prep1- /- ES cells which belong to gene ontology categories not enriched in the E11.5 Prep1i/i differentiated embryo, including in particular the Wnt and Fgf pathways. Indeed, we find aberrant Wnt and Fgf expression levels in the Prep1-/- ES cells which agrees with a deficient embryoid bodies (EBs) differentiation. Re-establishment of the Prep1 level rescues the phenotype. [ChIP-Seq] Examination of genome-wide Prep1 binding in mouse ES cells using ChIP-seq and Illumina GAII sequencing. [RNA-Seq] Examination of gene expression in wild type and Prep1-/- mouse ES cells using RNA-seq and Illumina GAII sequencing.
Project description:We have defined the tumor and tumor suppressor signature for Meis1 and Prep1 (pKnox1), respectively, using ChIP-seq and RNA-seq in a cell system in which tumor suppressor Prep1 and oncogene Meis1 compete for tumorigenesis [GSE54221; GSE58802]. In this paper we report that the number of Meis1 or Prep1 DNA binding sites increases linearly with the level of expression of the two transcription factors. Overexpression of Meis1 induces tumors. At the molecular level it modifies the DNA target specificity by increasing the number of low-affinity binding sites, which results in a different choice of consensus sequences with predominance of sites normally bound by the AP1 transcription factor family. Upon concomitant overexpression of Prep1 and Meis1 tumorigenesis is inhibited. Prep1 dominates over Meis1 not only because it partially decreases Meis1 protein level but also because it prevents the binding to a substantial fraction of the low affinity binding sites. Overall, overexpression of Prep1 reverses the nature of the bound and regulated genes from stimulatory to inhibitory of signal transduction and transcription, which suppresses tumorigenesis. By identifying the Meis1 tumor signature, specific relevant signaling pathways are identified. In line with these results, tumorigenic Meis1-overexpressing cells are uniquely hypersensitive to inhibitors of the MAPK/Akt pathways. Examination of Prep1 and Meis1 in five cell type
Project description:Prep1 is a tumor-suppressor, whereas Meis1 is an oncogene. We show that to perform these activities in MEFs both proteins competitively hetero-dimerize with Pbx1. Meis1 alone transforms Prep1-deficient fibroblasts while Prep1 overexpression inhibits Meis1 tumorigenicity. Pbx1 can therefore alternatively act as oncogene or tumor-suppressor. Prep1 post-translationally controls the level of Meis1 decreasing its stability by sequestering Pbx1. The different levels of Meis1 and the presence of Prep1 are followed at the transcriptional level by the induction of specific transcriptional signatures. The decrease of Meis1 prevents Meis1 interaction with Ddx3x and Ddx5, which are essential for Meis1 tumorigenesis, and modifies the growth promoting DNA binding landscape of Meis1 to the growth controlling landscape of Prep1. Hence the key feature of Prep1 tumor inhibiting activity is the control of Meis1 stability. Examination of Prep1 and Meis1 in three cell type
Project description:Prep1 is a tumor-suppressor, whereas Meis1 is an oncogene. We show that to perform these activities in MEFs both proteins competitively hetero-dimerize with Pbx1. Meis1 alone transforms Prep1-deficient fibroblasts while Prep1 overexpression inhibits Meis1 tumorigenicity. Pbx1 can therefore alternatively act as oncogene or tumor-suppressor. Prep1 post-translationally controls the level of Meis1 decreasing its stability by sequestering Pbx1. The different levels of Meis1 and the presence of Prep1 are followed at the transcriptional level by the induction of specific transcriptional signatures. The decrease of Meis1 prevents Meis1 interaction with Ddx3x and Ddx5, which are essential for Meis1 tumorigenesis, and modifies the growth promoting DNA binding landscape of Meis1 to the growth controlling landscape of Prep1. Hence the key feature of Prep1 tumor inhibiting activity is the control of Meis1 stability. Examination of Prep1 and Meis1 in two cell types
Project description:Down-regulation (DR) of PREP1 (aka PKNOX1) tumor suppressor induces H2Ax foci in human fibroblasts. Here we have analyzed the effect of PREP1 DR on DNA replication using cell cycle analysis, Repliseq, DNA combing, ChIP-seq, RNA-seq and immunofluorescence (IF). In human cells, PREP1 DR similarly affects both the rate of DNA replication and the progression of cells through the S phase. Genome wide, PREP1 DR induces late to early DNA replication shifts in normally late-replicated genomic regions amounting to 25% of the genome, in addition to unscheduled origins firing. A concomitant strong increase of unidirectional replication forks explains the appearance of DNA damage foci. The DNA target of PREP1 DR is the Lamin Associated DNA, in agreement with the simultaneous decrease of Lamin B1. Therefore PREP1 is a novel regulator of replication timing and Lamin B1 level, which ChIP-seq and RNA-seq data indicate as independent from its transcriptional activity. This activity must constitute the basis for its tumor suppression function.
Project description:Prep1 is a tumor-suppressor, whereas Meis1 is an oncogene. We show that to perform these activities in MEFs both proteins competitively hetero-dimerize with Pbx1. Meis1 alone transforms Prep1-deficient fibroblasts while Prep1 overexpression inhibits Meis1 tumorigenicity. Pbx1 can therefore alternatively act as oncogene or tumor-suppressor. Prep1 post-translationally controls the level of Meis1 decreasing its stability by sequestering Pbx1. The different levels of Meis1 and the presence of Prep1 are followed at the transcriptional level by the induction of specific transcriptional signatures. The decrease of Meis1 prevents Meis1 interaction with Ddx3x and Ddx5, which are essential for Meis1 tumorigenesis, and modifies the growth promoting DNA binding landscape of Meis1 to the growth controlling landscape of Prep1. Hence the key feature of Prep1 tumor inhibiting activity is the control of Meis1 stability.
Project description:Prep1 is a tumor-suppressor, whereas Meis1 is an oncogene. We show that to perform these activities in MEFs both proteins competitively hetero-dimerize with Pbx1. Meis1 alone transforms Prep1-deficient fibroblasts while Prep1 overexpression inhibits Meis1 tumorigenicity. Pbx1 can therefore alternatively act as oncogene or tumor-suppressor. Prep1 post-translationally controls the level of Meis1 decreasing its stability by sequestering Pbx1. The different levels of Meis1 and the presence of Prep1 are followed at the transcriptional level by the induction of specific transcriptional signatures. The decrease of Meis1 prevents Meis1 interaction with Ddx3x and Ddx5, which are essential for Meis1 tumorigenesis, and modifies the growth promoting DNA binding landscape of Meis1 to the growth controlling landscape of Prep1. Hence the key feature of Prep1 tumor inhibiting activity is the control of Meis1 stability.
Project description:We have defined the tumor and tumor suppressor signature for Meis1 and Prep1 (pKnox1), respectively, using ChIP-seq and RNA-seq in a cell system in which tumor suppressor Prep1 and oncogene Meis1 compete for tumorigenesis [GSE54221; GSE58802]. In this paper we report that the number of Meis1 or Prep1 DNA binding sites increases linearly with the level of expression of the two transcription factors. Overexpression of Meis1 induces tumors. At the molecular level it modifies the DNA target specificity by increasing the number of low-affinity binding sites, which results in a different choice of consensus sequences with predominance of sites normally bound by the AP1 transcription factor family. Upon concomitant overexpression of Prep1 and Meis1 tumorigenesis is inhibited. Prep1 dominates over Meis1 not only because it partially decreases Meis1 protein level but also because it prevents the binding to a substantial fraction of the low affinity binding sites. Overall, overexpression of Prep1 reverses the nature of the bound and regulated genes from stimulatory to inhibitory of signal transduction and transcription, which suppresses tumorigenesis. By identifying the Meis1 tumor signature, specific relevant signaling pathways are identified. In line with these results, tumorigenic Meis1-overexpressing cells are uniquely hypersensitive to inhibitors of the MAPK/Akt pathways.