Project description:PLZF (promyelocytic leukemia zinc finger) is a transcription factor acting as a global regulator of hematopoietic commitment. PLZF displays an epigenetic specificity by recruiting chromatin-modifying factors but little is known about its role in remodeling chromatin of cells committed towards a given specific hematopoietic lineage. In murine myeloid progenitors, we decipher a new role for PLZF in restraining active genes and enhancers by targeting acetylated lysine 27 of Histone H3 (H3K27ac). Functional analyses reveal that active enhancers bound by PLZF are involved in biological processes related to metabolism and associated with hematopoietic aging. Comparing the epigenome of young and old myeloid progenitors, we reveal that H3K27ac variation at active enhancers is a hallmark of hematopoietic aging. Taken together, these data suggest that PLZF, associated with active enhancers, appears to restrain their activity as an epigenetic gatekeeper of hematopoietic aging.
Project description:PLZF (promyelocytic leukemia zinc finger) is a transcription factor acting as a global regulator of hematopoietic commitment. PLZF displays an epigenetic specificity by recruiting chromatin-modifying factors but little is known about its role in remodeling chromatin of cells committed toward a given specific hematopoietic lineage. In murine myeloid progenitors, we decipher a new role for PLZF in restraining active genes and enhancers by targeting acetylated lysine 27 of Histone H3 (H3K27ac). Functional analyses reveal that active enhancers bound by PLZF are involved in biological processes related to metabolism and associated with hematopoietic aging. Comparing the epigenome of young and old myeloid progenitors, we reveal that H3K27ac variation at active enhancers is a hallmark of hematopoietic aging. Taken together, these data suggest that PLZF, associated with active enhancers, appears to restrain their activity as an epigenetic gatekeeper of hematopoietic aging.
Project description:To uncover gene programs that are regulated by PLZF in the early hematopoietic compartment, we performed micro array-based gene expression analysis of wild-type (WT) or PLZF-mutant (Zbtb16lu/lu) KSLs. DNA-microarrays were used to define and compare the transcriptional profiles of KSL cells isolated from Zbtb16lu/lu mice and WT mice (n=4).
Project description:Natural killer (NKT) T cells exhibit tissue distribution, surface phenotype, and functional responses that are strikingly different from those of conventional T cells. The transcription factor PLZF is responsible for most of these properties, as its ectopic expression in conventional T cells is sufficient to confer to them an NKT-like phenotype. The molecular program downstream of PLZF, however, is largely unexplored. Here we report that PLZF regulates the expression of a surprisingly small set of genes, many with known immune functions. This includes several established components of the NKT cell developmental program. Transcriptional program downstream of PLZF in gammadelta NKT cells was analyzed by comparing wt, heterozygous and PLZF-deficient gammadelta NKT cells
Project description:MTD project_description Inflammation and decreased stem cell function characterize organism aging, yet the relationship between these factors remains incompletely understood. This study shows that aged hematopoietic stem and progenitor cells exhibit increased ground-stage NF-κB activity, which enhances their responsiveness to undergo differentiation and loss of self-renewal in response to inflammation. The study identifies Rad21/cohesin as a critical mediator of NF-κB signals, by increasing chromatin accessibility of inter-/intra-genic and enhancer regions. Rad21/NF-κB are required for normal differentiation, but limit self-renewal of hematopoietic stem cells (HSCs) during aging and inflammation in an NF-κB dependent manner. HSCs from aged mice fail to downregulate Rad21/cohesin and inflammation/differentiation inducing signals in the resolution phase after acute inflammation. and The inhibition of cohesin/NF-κB is sufficient to revert the hypersensitivity of aged HSPCs to inflammation-induced differentiation. During aging, myeloid-biased HSCs with disrupted and naturally occurring reduced expression of Rad21/cohesin are increasingly selected over lymphoid-biased HSCs. Together, Rad21/cohesin mediated NF-κB signaling limits HSPC function during aging and selects for cohesin deficient HSCs with myeloid skewed differentiation.
Project description:The transcription factor PLZF (promyelocytic leukemia zinc finger protein) acts as an epigenetic regulator balancing self-renewal and differentiation of hematopoietic cells through binding to various chromatin-modifying factors. First described as a transcriptional repressor, PLZF is also associated with active transcription, although the molecular bases underlying the differences are unknown. Here, we reveal that, in a hematopoietic cell line, PLZF is predominantly associated with transcribed genes. Additionally, we identify a new association between PLZF and the histone methyltransferase, EZH2 at the genomic level. We find that co-occupancy of PLZF and EZH2 on chromatin at PLZF target genes is not associated with SUZ12 or trimethylated lysine 27 of histone H3 (H3K27me3) but with the active histone mark H3K4me3 and active transcription. Removal of EZH2 leads to an increase of PLZF binding and increased in gene expression. Our results suggest a new role of EZH2 in restricting PLZF positive transcriptional activity independently of its canonical PRC2 activity.
Project description:Natural killer (NKT) T cells exhibit tissue distribution, surface phenotype, and functional responses that are strikingly different from those of conventional T cells. The transcription factor PLZF is responsible for most of these properties, as its ectopic expression in conventional T cells is sufficient to confer to them an NKT-like phenotype. The molecular program downstream of PLZF, however, is largely unexplored. Here we report that PLZF regulates the expression of a surprisingly small set of genes, many with known immune functions. This includes several established components of the NKT cell developmental program.
Project description:The PLZF-RARa fusion oncoprotein is overexpressed in the t(11;17) subtype of acute promyelocytic leukemia. Gene expression microarrays were used to identify genes involved in leukemic transformation. We used microarray to detect gene expression changes induced by the PLZF-RARa fusion oncoprotein in the U937 cell line Experiment Overall Design: The U937T:PLZF-RARa cell line was engineered to express PLZF-RARa upon tetracycline removal. PLZF-RARa was induced for 48hr and RNA was extracted and hybridized to Affymetrix HGU133Plus2.0 Chips
Project description:To determine how aging impacts gene expression in hematopoietic stem cells (HSCs), human CD34+ cells from bone marrow (34BM) and mobilized stem cell products (34P38NPBSC) were examined using microarray-based expression profiling. Differential expression changes were confirmed by microarray comparisons of younger and older expanded T-cell populations.
Project description:The transcription factor PLZF (promyelocytic leukemia zinc finger) is encoded by the BTB domain-containing 16 (Zbtb16) gene. Its repressor function regulates specific transcriptional programs. During the development of invariant natural killer T (NKT) cells, PLZF is expressed and directs their effector program but the detailed mechanisms underlying PLZF regulation of multi-stage NKT cell developmental program are not well understood. This study investigated the role of acetylation-induced PLZF activation on NKT cell development by analyzing mice expressing a mutant form of PLZF mimicking constitutive acetylation (PLZFON mice). NKT populations in PLZFON mice were reduced in proportion and numbers of cells, and the cells present were blocked at the transition from developmental stage 1 to stage 2. NKT cell subset differentiation was also altered, with T-bet+ NKT1 and RORt+ NKT17 subsets dramatically reduced, and the emergence of a T-bet-RORt- NKT cell subset with features of cells in early developmental stages rather than mature NKT2 cells. Preliminary analysis of DNA methylation patterns suggested that activated PLZF acts on the DNA methylation signature to regulate NKT cells’ entry into the early stages of development, while repressing maturation. In wild-type NKT cells, deacetylation of PLZF is possible, allowing subsequent NKT cell differentiation. Interestingly, development of other innate lymphoid and myeloid cells, that are dependent on PLZF for their generation, is not altered in PLZFON mice highlighting lineage specific regulation. Overall, we propose that specific epigenetic control of PLZF through acetylation levels is required to regulate normal NKT cell differentiation. Key points: Constitutive acetylation of PLZF (PLZFON) blocks NKT cell development. PLZFON might act on the DNA methylation signature to control gene expression. PLZF acetylation levels regulate normal NKT cell differentiation.