Project description:Promyelocytic Leukemia Protein (PML) was first identified as a fusion product with the retinoic acid receptor alpha in Acute Promyelocytic Leukemia (APL). Although PML has previously been studied in cancer progression and various physiological processes, little is known about its functions in Embryonic Stem Cells (ESC). Here, we report that PML contributes to the maintenance of the ESC self-renewal by controlling the cell-cycle and sustaining the expression levels of crucial pluripotency factors. Transcriptomic analysis showed that the ablation of PML renders ESC prone to exit from the naïve and acquire a primed-like pluripotent cell state. During differentiation PML influences cell fate decision by regulation of Tbx3. PML loss compromises the reprogramming ability of embryonic fibroblasts to induced Pluripotent Stem Cells (iPSC) by inhibiting the TGFβ pathway at the very early stages. Collectively, these results designate PML as a member of the regulatory network for ESC pluripotency and somatic cell reprogramming.
Project description:The transcription factor NF-κB is considered the master regulator of the immune response but also acts broadly to regulate gene expression that influences cell survival, proliferation and differentiation. Post-translational modification of NF-κB, phosphorylation in particular, is essential for the transactivation activity of NF-κB. Emerging evidence suggests that the regulation of NF-κB in the nucleus is critical in controlling gene expression. Promyelocytic Leukemia (PML) is a nuclear protein that forms nuclear bodies (PML NBs), sub-nuclear structures that are associated with transcriptionally active genomic regions that have been implicated in multiple processes such as apoptosis, senescence and anti-viral responses. Chromosomal translocations leading to the expression of a PML-retinoic acid receptor-α (PML-RARα) fusion protein are causative for acute promyelocytic leukemia (APL) characterised by a differentiation block at the promyelocytic state of myeloid development. Here we demonstrate that PML is required for phosphorylation of NF-κB p65 and that PML is essential for NF-κB- induced transcriptional responses. Our analysis of available transcriptional profiles of all-trans retinoic acid treated acute promyelocytic leukemia (APL) cells identifies a NF-κB transcriptional programme suppressed by PML-RARα. We further demonstrate that PML-RARα inhibits NF-κB phosphorylation and transcriptional activity. Our findings demonstrate a critical role for PML in promoting NF-κB transcriptional activity which may contribute to APL initiation and maintenance. WT and PML-/- MEFs were analysed for gene expression analysis. Total of 12 samples, inlcluding triplicates were utilized. WT MEFs and PML-/- were stimulated with TNFα for three hours and analysed for gene expresison using unstimulated WT MEFs as control.
Project description:NB4 is a cell line model of acute promyelocytic leukemia (APL).The t(15;17) translocation and consequent expression of the PML (Promyelocytic Leukemia Protein)/RARalpha (Retinoic Acid Receptor Alpha) fusion protein blocks differentiation at the promyelocytic stage.The PML portion of the PML/RARalpha fusion protein has a high affinity for the corepression complex, preventing RARalpha transcriptional activity. To induce complete remission in a high proportion of patients, a pharmacological dose of ATRA is required to destabilize this interaction and re-establish the differentiation program. Keywords: SAGE Sau3A
Project description:Acute Promyelocytic Leukemia (APL) is a fatal subtype of leukemia driven by the translocation between genes encoding the Promyelocytic Leukemia (PML) protein and the Retinoic Acid Receptor alpha (RARa) protein. We use mouse hematopoietic progenitor cells expressing PML-RARa and dissect the dynamic changes in the epigenome, transcriptome and genome architecture triggered by the expression of this oncogenic transcription factor during leukemic transformation. We find that PML-RARa induces a continuum of topologic and transcriptional alterations, mostly affecting distal regulatory elements. Furthermore, we identify Klf4 ― a master regulator of hematopoietic differentiation ― as an early mis-regulated gene during leukemogenesis, and deconstruct the dynamic alterations in long-range interactions, histone modifications and transcriptional output triggered by PML-RARa expression at the Klf4 locus. Our study provides a comprehensive overview of the dynamic genomic and transcriptomic alterations induced by PML-RARa, which ultimately block hematopoietic differentiation and induce leukemic transformation.
Project description:Acute promyelocytic leukemia (APL) is characterized by a specific t(15;17) chromosome translocation that generates the promyelocytic leukemia/retinoic acid receptor-α (PML/RARα) fusion gene. However, the mechanism underlying PML/RARα mediated transcriptional dysregulation remain unclear. Here, we performed the transcription profiling in NB4, an APL patient-derived cell line.
Project description:Acute promyelocytic leukemia (APL) is characterized by a specific t(15;17) chromosome translocation that generates the promyelocytic leukemia/retinoic acid receptor-α (PML/RARα) fusion gene. However, the mechanism underlying PML/RARα mediated transcriptional dysregulation remain unclear. Here, we performed the transcription profiling of BRD4 in NB4, an APL patient-derived cell line.
Project description:Acute promyelocytic leukemia (APL) is characterized by a specific t(15;17) chromosome translocation that generates the promyelocytic leukemia/retinoic acid receptor-α (PML/RARα) fusion gene. However, the global association between PML/RARα and transcriptional co-regulators, and the rules of their association in governing the key processes during the leukemogenesis remain unclear. Here, we performed the genome-wide binding profiling of PML/RARα and BRD4 in NB4, an APL patient-derived cell line. Moreover, we also performed ChIP-seq of PML/RARα and BRD4 upon genetic or pharmacological pertubation of PML/RARα or BRD4 to determine how they target regulatory elements.
Project description:The transcription factor NF-κB is the master regulator of the immune response but also regulates gene expression to influences cell survival, proliferation and differentiation. Inducible site-specific phosphorylation of NF-κB is critical for its activity and appears to be important in gene specific transcriptional control. Promyelocytic Leukemia (PML) is a nuclear protein that forms sub-nuclear structures termed nuclear bodies associated with transcriptionally active genomic regions. We demonstrate that PML promotes NF-κB- induced transcriptional responses by promoting the phosphorylation of NF-κB p65 at key regulatory sites. Our findings demonstrate a critical role for PML in promoting NF-κB transcriptional activity through signal induced post-translational modifications.
Project description:Acute promyelocytic leukemia (APL) is characterized by a specific t(15;17) chromosome translocation that generates the promyelocytic leukemia/retinoic acid receptor-α (PML/RARα) fusion gene. However, the global association between PML/RARα and transcriptional co-regulators, and the rules of their association in governing the key processes during the leukemogenesis remain obscure. Here, we performed the genome-wide binding profiling of PML/RARα, HDAC1 and P300, in NB4, an APL patient-derived cell line. We found that PML/RARα targets could be classified into two classes. Moreover, we also performed ChIP-seq of H3K27ac to determine super-enhancers in NB4. We identified a novel function of PML/RARα in super-enhancer regulation during the leukemogenesis of APL.
Project description:The promyelocytic leukemia (PML) body is a phase-separated nuclear structure composed of various proteins including several chromatin regulators, and physically associates with chromatin. To address functional roles of the PML-chromatin association, we conducted genome-wide profiling of PML body-associated regions.