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:Abstract: The Promyelocytic Leukemia protein (PML) and its associated nuclear bodies have re-cently emerged as essential factors for maintaining the characteristics of embryonic stem (ES) cells. However, the full repertoire of PML driven gene regulatory events in ES cells is not resolved. In this report we have studied the role of PML in shaping the proteomic and SUMO proteomic landscape in ES cells. Our analysis of the PML KD proteome revealed a suppression of proteins related with self-renewal and an up-regulation of proteins vital for translation and proteasome functions, reflecting a cellular transition from pluripotency to differentiation. Major targets of PML-directed sumoylation include pluripotency factors, chromatin organizers and cell cycle regulators. We demonstrate that PML promotes the sumoylation of SALL1 and CDCA8, two proteins that are highly expressed in undifferentiated ES cells. SALL1 sumoylation increases the activation of the Wnt pathway, contributing to its ability to inhibit ES cell differentiation. Similarly, CDCA8 sumoylation enhances its capacity to promote cell proliferation. Our results demonstrate that PML maintains ES cell functions by modulating the abundance or sumoylation of key regulators involved in pluripotency and cell cycle progression.
Project description:Abstract: The Promyelocytic Leukemia protein (PML) and its associated nuclear bodies have re-cently emerged as essential factors for maintaining the characteristics of embryonic stem (ES) cells. However, the full repertoire of PML driven gene regulatory events in ES cells is not resolved. In this report we have studied the role of PML in shaping the proteomic and SUMO proteomic landscape in ES cells. Our analysis of the PML KD proteome revealed a suppression of proteins related with self-renewal and an up-regulation of proteins vital for translation and proteasome functions, reflecting a cellular transition from pluripotency to differentiation. Major targets of PML-directed sumoylation include pluripotency factors, chromatin organizers and cell cycle regulators. We demonstrate that PML promotes the sumoylation of SALL1 and CDCA8, two proteins that are highly expressed in undifferentiated ES cells. SALL1 sumoylation increases the activation of the Wnt pathway, contributing to its ability to inhibit ES cell differentiation. Similarly, CDCA8 sumoylation enhances its capacity to promote cell proliferation. Our results demonstrate that PML maintains ES cell functions by modulating the abundance or sumoylation of key regulators involved in pluripotency and cell cycle progression.
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 the specific chromosome translocation t(15;17) that generates the promyelocytic leukemia/retinoic acid receptor-α (PML/RARα) fusion gene. Arsenic trioxide has been intensively reported to directly and rapidly degrade the PML/RARα fusion protein. Here, we treated NB4 cells (a widely used APL cell line) with arsenic trioxide and performed RNA-seq analysis to identify differentially expressed genes upon arsenic trioxide treatment.
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.