Identifying chromatin associations with promyelocytic leukemia nuclear bodies using immunoTRAP
Ontology highlight
ABSTRACT: 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:PML nuclear body (PML NB) recruits different client proteins under different cell context. We used TurboID proximity labeling (PL) method followed by MS to determine the composition of PML NBs in mESCs, differentiated cells, and NaAsO2-treated mESCs.
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:In spite of the crucial tasks fulfilled by the subnuclear structures known as PML nuclear bodies (PML-NBs) in mammalian cells, the presence of PML-NBs in plant cells could not be shown yet. Interestingly, the key organizer of PML-NBs, human promyelocytic leukemia protein (PML), is not targeted to structures resembling PML-NBs when expressed heterologously in plants, but localizes to interchromosomal areas associated with the nucleolus. In order to identify plant proteins interacting with human PML, a GFP-fusion protein was ectopically expressed in Nicotiana benthamiana using Agrobacterium tumefaciens mediated transformation. The bait protein as well as potential interactors were immunoprecipitated by use of magnetic GFP-Trap beads (Chromotek). Precipitated proteins were analyzed by Nano-LC-MS/MS.
Project description:U2OS PML-/- cells were reconstituted with YFP-PML-V of three types: WT, A216T or L217F. These cell lines were used to purify YFP-PML bodies using anti-GFP nanobody beads from cells either treated or not with arsenic (1uM for 2h). Protein samples were monitored for PML post-translational modifications and associated proteomes to try to understand why people with acute promyelocytic leukaemia that is resistant to arsenic treatment have these mutations.
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:A global view of PML-RAR? transcriptional functions was obtained by genome-wide binding and chromatin modification analyses, combined with genome wide expression data. Complete Abstract: The translocation t(15;17) generates the chimeric PML-RAR? transcription factor that is the initiating event of acute promyelocytic leukemia. A global view of PML-RAR? transcriptional functions was obtained by genome-wide binding and chromatin modification analyses, combined with genome wide expression data. ChIP-chip experiments identified 372 direct genomic PML-RAR? targets. A subset of these was confirmed in primary acute promyelocytic leukemia. Direct PML-RARá targets include regulators of global transcriptional programs as well as critical regulatory genes for basic cellular functions such as cell cycle control and apoptosis. PML-RAR? binding universally led to HDAC1 recruitment, loss of histone H3 acetylation, increased tri-methylation of histone H3 lysine 9 and unexpectedly increased tri-methylation of histone H3 lysine 4. The binding of PMLRAR? to target promoters and the resulting histone modifications resulted in mRNA repression of functionally relevant genes. Taken together our results reveal that the transcription factor PML-RAR? regulates key cancer related genes and pathways by inducing a repressed chromatin formation on its direct genomic target genes. Keywords: ChIP on Chip U937 transfected with an inducible PML-RAR?/empty vecor were induced, harvested and Chromatin-Ips for PML, AcH3 followed by microarray hybridasation were carried out. For detailed procedures see Hoemme et al. "Chromatin modifications induced by PML-RARalpha repress critical targets in leukemogenesis as analyzed by ChIP-Chip"
Project description:The promyelocytic leukemia (PML) protein organizes nuclear aggregates known as PML nuclear bodies (PML-NBs), where many transcription factors and transcriptional regulators converge to be regulated. Specific associations of PML and PML-NBs with chromatin are described in different cell types, further implicating PML in transcriptional regulation. However, a complete understanding of the functional consequences of PML association to DNA in a cellular context where it regulates relevant phenotypes is still lacking.We examined the role of PML in chromatin association and transcription in triple-negative breast cancer (TNBC), a pathological condition where PML exerts important oncogenic functions. We find that PML associates discontinuously with large heterochromatic PML-associated domains (PADs) that contain gene-rich euchromatic sub-domains locally depleted of PML. PML promotes heterochromatic organization in PADs and expression of pro-metastatic genes embedded in these sub-domains. Importantly, this occurs outside PML-NBs, suggesting that nucleoplasmic PML exerts a cell type-relevant function of transcriptional regulation. PML also plays an indirect regulatory function in TBNC cells by promoting the expression of pro-metastatic genes outside PADs.Our findings demonstrate that PML is an important transcriptional regulator of metastasis and pro-oncogenic metagenes in TNBC cells, via distinct molecular activities that include indirect transcriptional regulation and direct epigenetic organization of heterochromatin domains that embed regions of localized transcriptional activity.
Project description:The promyelocytic leukemia (PML) protein organizes nuclear aggregates known as PML nuclear bodies (PML-NBs), where many transcription factors and transcriptional regulators converge to be regulated. Specific associations of PML and PML-NBs with chromatin are described in different cell types, further implicating PML in transcriptional regulation. However, a complete understanding of the functional consequences of PML association to DNA in a cellular context where it regulates relevant phenotypes is still lacking.We examined the role of PML in chromatin association and transcription in triple-negative breast cancer (TNBC), a pathological condition where PML exerts important oncogenic functions. We find that PML associates discontinuously with large heterochromatic PML-associated domains (PADs) that contain gene-rich euchromatic sub-domains locally depleted of PML. PML promotes heterochromatic organization in PADs and expression of pro-metastatic genes embedded in these sub-domains. Importantly, this occurs outside PML-NBs, suggesting that nucleoplasmic PML exerts a cell type-relevant function of transcriptional regulation. PML also plays an indirect regulatory function in TBNC cells by promoting the expression of pro-metastatic genes outside PADs.Our findings demonstrate that PML is an important transcriptional regulator of metastasis and pro-oncogenic metagenes in TNBC cells, via distinct molecular activities that include indirect transcriptional regulation and direct epigenetic organization of heterochromatin domains that embed regions of localized transcriptional activity.
Project description:The promyelocytic leukemia (PML) protein organizes nuclear aggregates known as PML nuclear bodies (PML-NBs), where many transcription factors and transcriptional regulators converge to be regulated. Specific associations of PML and PML-NBs with chromatin are described in different cell types, further implicating PML in transcriptional regulation. However, a complete understanding of the functional consequences of PML association to DNA in a cellular context where it regulates relevant phenotypes is still lacking.We examined the role of PML in chromatin association and transcription in triple-negative breast cancer (TNBC), a pathological condition where PML exerts important oncogenic functions. We find that PML associates discontinuously with large heterochromatic PML-associated domains (PADs) that contain gene-rich euchromatic sub-domains locally depleted of PML. PML promotes heterochromatic organization in PADs and expression of pro-metastatic genes embedded in these sub-domains. Importantly, this occurs outside PML-NBs, suggesting that nucleoplasmic PML exerts a cell type-relevant function of transcriptional regulation. PML also plays an indirect regulatory function in TBNC cells by promoting the expression of pro-metastatic genes outside PADs.Our findings demonstrate that PML is an important transcriptional regulator of metastasis and pro-oncogenic metagenes in TNBC cells, via distinct molecular activities that include indirect transcriptional regulation and direct epigenetic organization of heterochromatin domains that embed regions of localized transcriptional activity.
Project description:TRIM33 is a chromatin reader required for mesendoderm differentiation upon activation of Nodal signaling. But, its role in mESCs is still elusive. Here, we found that TRIM33 co-localizes with promyelocytic leukemia nuclear bodies (PML NBs) specifically in mESCs to mediate Nodal signaling-directed transcription of Lefty1/2. We showed that TRIM33 puncta formation in mESCs depends on PML and specific assembly of PML NBs. Moreover, TRIM33 and PML co-regulate Lefty1/2 expression in mESCs. In addition, both PML and mESCs-specific PML NBs are required for TRIM33 recruitment at Lefty1/2 loci. Remarkably, PML NBs directly associate with the Lefty1/2 loci in mESCs. Finally, a TurboID proximity labeling experiment confirmed that TRIM33 is highly enriched in the mESCs-specific PML NBs. Thus, our study provides the mechanistic insight about TRIM33 condensate in regulating Nodal signaling-directed transcription in mESCs, it also reveals that PML NBs recruit distinct sets of client proteins in cell context dependent manner.