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 of BRD4 in NB4, an APL patient-derived cell line.
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.
Project description:Mature oocyte cytoplasm can reprogram somatic cell nuclei to the pluripotent state through a series of sequential events including protein exchange between the donor nucleus and ooplasm, chromatin remodeling, and pluripotency gene reactivation. Maternal factors that are responsible for this reprogramming process remain largely unidentified. Here, we demonstrate that knockdown of histone variant H3.3 in mouse oocytes results in compromised reprogramming and down-regulation of key pluripotency genes; and this compromised reprogramming both for developmental potentials and transcription of pluripotency genes can be rescued by injecting exogenous H3.3 mRNA, but not H3.2 mRNA into oocytes in somatic cell nuclear transfer (SCNT) embryos. We show that maternal H3.3, and not H3.3 in the donor nucleus, is essential for successful reprogramming of somatic cell nucleus into the pluripotent state. Furthermore, H3.3 is involved in this reprogramming process by remodeling the donor nuclear chromatin through replacement of donor nucleus-derived H3 with de novo synthesized maternal H3.3 protein. Our study shows that H3.3 is a crucial maternal factor for oocyte reprogramming and provides a practical model to directly dissect the oocyte for its reprogramming capacity. Transcriptome sequencing of 4-cell NT embryos, Luciferase 4-cell SCNT embryos, 4-cell NT embryos_H3.3KD, 4-cell NT embryos_H3.3KD+H3.3mRNA, H3.3 KD + H3.2 mRNA SCNT embryos
Project description:Acute promyelocytic leukemia (APL) is a subtype of myeloid leukemia characterized by differentiation block at the promyelocyte stage. Besides the presence of chromosomal rearrangement t(15;17) leading to formation of PML-RARA fusion, other genetic alterations have also been implicated in APL. Here, we performed comprehensive mutational analysis of primary and relapse APL to identify somatic alterations which cooperate with PML-RARA in the pathogenesis of APL. We explored the mutational landscape using whole-exome (n=12) and subsequent targeted sequencing of 398 genes in 153 primary and 69 relapse APL. Both primary and relapse APL harbored an average of eight non-silent somatic mutations per exome. We observed recurrent alterations of FLT3, WT1, NRAS and KRAS in the newly diagnosed APL, while mutations in other genes commonly mutated in myeloid leukemia were rarely detected. The molecular signature of APL relapse was characterized by emergence of frequent mutations in PML and RARA genes. Our sequencing data also demonstrates incidence of loss-of-function mutations in previously unidentified genes, ARID1B and ARID1A, both of which encode for key components of the SWI/SNF complex. We show that knockdown of ARID1B in APL cell line, NB4, results in large scale activation of gene expression and reduced in vitro differentiation potential. Studying the effects of silensing ARID1B gene in NB4 cell lines