Project description:Studies using fluorescence in situ hybridization (FISH) have attempted to determine whether specific gene loci associate with promyelocytic leukemia nuclear bodies (PML NBs). Two drawbacks accompany this approach; the lack of spatial resolution inherent with the technique, and the a priori basis for selecting which genes to probe. To overcome these limitations, we developed a technique, which we call immunoTRAP, which purifies the DNA contacting PML NBs at molecular dimensions. When we combined the immunoTRAP technique with immunoFISH and microarray analysis, not only did we verify a TP53-PML NB association, but were able also to identify novel locus associations such as PML, ABCA7, and TFF1. In addition, we observed that these associations are cell type specific, and induction of significantly higher levels of PML gene expression, as well as other physiological changes brought about by interferon treatment, can lead to a physical association of the PML gene with PML NBs in normal human fibroblasts. Thus, immunoTRAP is a technique capable of identifying the chromatin associations around nuclear subcompartments and is amenable for further downstream applications such as microarray analysis or deep sequencing. Identification of binding (Cy5) to PML vs. to non-specific binding in Jurkat cells (n=5)
Project description:Studies using fluorescence in situ hybridization (FISH) have attempted to determine whether specific gene loci associate with promyelocytic leukemia nuclear bodies (PML NBs). Two drawbacks accompany this approach; the lack of spatial resolution inherent with the technique, and the a priori basis for selecting which genes to probe. To overcome these limitations, we developed a technique, which we call immunoTRAP, which purifies the DNA contacting PML NBs at molecular dimensions. When we combined the immunoTRAP technique with immunoFISH and microarray analysis, not only did we verify a TP53-PML NB association, but were able also to identify novel locus associations such as PML, ABCA7, and TFF1. In addition, we observed that these associations are cell type specific, and induction of significantly higher levels of PML gene expression, as well as other physiological changes brought about by interferon treatment, can lead to a physical association of the PML gene with PML NBs in normal human fibroblasts. Thus, immunoTRAP is a technique capable of identifying the chromatin associations around nuclear subcompartments and is amenable for further downstream applications such as microarray analysis or deep sequencing.
Project description: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 roles of PML bodies in transcriptional regulation, we performed RNA-seq analyses with wild-type and PMK knockout mESCs
Project description:Promyelocytic leukemia (PML) body is a phase-separated nuclear structure composed of various proteins including several chromatin regulators, and physically associates with chromatin, implying its crucial roles for particular genome functions. To investigate functional roles of PML bodies in chromatin organization, we conducted ATAC-seq with wild-type and PML KO mESCs.
Project description:Promyelocytic leukemia (PML) body is a phase-separated nuclear structure composed of various proteins including several chromatin regulators, and physically associates with chromatin, implying its crucial roles for particular genome functions. To investigate roles of PML bodies in transcriptional regulation, we conducted ChIP-seq analysis for histone modifications, including H3K4me3, H3K27ac, H3K27me3, and H3K9ac with wild-type and PML knockout mESCs.
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:Kynureninase is a member of a large family of catalytically diverse but structurally homologous pyridoxal 5'-phosphate (PLP) dependent enzymes known as the aspartate aminotransferase superfamily or alpha-family. The Homo sapiens and other eukaryotic constitutive kynureninases preferentially catalyze the hydrolytic cleavage of 3-hydroxy-l-kynurenine to produce 3-hydroxyanthranilate and l-alanine, while l-kynurenine is the substrate of many prokaryotic inducible kynureninases. The human enzyme was cloned with an N-terminal hexahistidine tag, expressed, and purified from a bacterial expression system using Ni metal ion affinity chromatography. Kinetic characterization of the recombinant enzyme reveals classic Michaelis-Menten behavior, with a Km of 28.3 +/- 1.9 microM and a specific activity of 1.75 micromol min-1 mg-1 for 3-hydroxy-dl-kynurenine. Crystals of recombinant kynureninase that diffracted to 2.0 A were obtained, and the atomic structure of the PLP-bound holoenzyme was determined by molecular replacement using the Pseudomonas fluorescens kynureninase structure (PDB entry 1qz9) as the phasing model. A structural superposition with the P. fluorescens kynureninase revealed that these two structures resemble the "open" and "closed" conformations of aspartate aminotransferase. The comparison illustrates the dynamic nature of these proteins' small domains and reveals a role for Arg-434 similar to its role in other AAT alpha-family members. Docking of 3-hydroxy-l-kynurenine into the human kynureninase active site suggests that Asn-333 and His-102 are involved in substrate binding and molecular discrimination between inducible and constitutive kynureninase substrates.
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.