Project description:B lymphopoiesis is the result of several cell lineage choices and differentiation steps whose perturbation leads to B cell malignancies. Cellular transitions for B cell generation have been associated with gene activation and silencing by networks of B cell specific transcription factors (TFs) and dynamic changes in DNA methylation. How gene repression is established and which lineage-specific transcriptional repressors are involved during B cell lymphopoiesis are still not totally understood. Here, by using our in vivo experimental approach, we have found that HDAC7 represses Tet2 enzyme in pro-B cells. In fact, HDAC7 deficient pro-B cells show a significant increase in the percentage of global 5-hydroxymethylation. To prove the role of HDAC7 in 5-hydroxymethylation, we have performed a genome-wide experimental approach. hMeDIP-sequencing experiments reveal an increase in the enrichment of this epigenetic modification at many loci related to lineage inappropriate genes. Our results corroborate that HDAC7 is an essential transcriptional regulator during early B cell development that silences lineage or functionally inappropriate genes and unveil an unexpected role of a class IIa HDAC in controlling DNA methylation
Project description:The establishment of proper epigenomic landscape is essential during B lymphocyte development in order to acquire a correct B cell identity at each cellular differentiation stage. We previously identified HDAC7 as a critical regulator of early B cell development. Its absence indeed led to the aberrant activation of inappropriate lineage genes, a reduction of proliferation and an increase in cell apoptosis. More recently, we have demonstrated that HDAC7 loss in infant pro-B-ALL associates with poor prognosis. Here we shed light into the HDAC7-mediated molecular mechanisms during early B cell development. HDAC7 deficiency drives not only the expression of inappropriate lineage genes, but also global chromatin de-condensation and deregulation of epigenetic regulators of DNA methylation and potential damaging elements. Specifically, HDAC7 absence induces the expression of TET2, which promotes DNA 5-hydroxymethylation and aberrant gene activation. HDAC7 deficiency also results in the uncontrolled expression of microRNAs and non-coding elements such as LINE-1 transposable elements. These findings are relevant for the mechanistic explanation of why HDAC7 is affected in multiple B-related hematological malignancies. Chromatin immunoprecipitation DNA-sequencing (ChIP-seq) for histone modifications H3K27ac and H3K27me3 in murine pro-B lymphocytes.
Project description:The establishment of proper epigenomic landscape is essential during B lymphocyte development in order to acquire a correct B cell identity at each cellular differentiation stage. We previously identified HDAC7 as a critical regulator of early B cell development. Its absence indeed led to the aberrant activation of inappropriate lineage genes, a reduction of proliferation and an increase in cell apoptosis. More recently, we have demonstrated that HDAC7 loss in infant pro-B-ALL associates with poor prognosis. Here we shed light into the HDAC7-mediated molecular mechanisms during early B cell development. HDAC7 deficiency drives not only the expression of inappropriate lineage genes, but also global chromatin de-condensation and deregulation of epigenetic regulators of DNA methylation and potential damaging elements. Specifically, HDAC7 absence induces the expression of TET2, which promotes DNA 5-hydroxymethylation and aberrant gene activation. HDAC7 deficiency also results in the uncontrolled expression of microRNAs and non-coding elements such as LINE-1 transposable elements. These findings are relevant for the mechanistic explanation of why HDAC7 is affected in multiple B-related hematological malignancies. Assay for Transposase-Accessible Chromatin with high-throughput sequencing (ATAC-seq) was performed in murine pro-B and pre-B lymphocytes.
Project description:B lymphocyte development is a complex process tightly controlled at the transcriptional level by the action of networks of transcription factors. The repression of genes from alternative lineages is necessary to ensure the acquisition of the correct B cell identity. However, the mechanisms of transcriptional repression during B cell generation are largely unknown. Here, using a conditional knockout mouse model, we show that the histone deacetylase HDAC7 is essential for B cell development. Early deletion of HDAC7 dramatically blocked B cell development at the pro-B cell stage and gave rise to a severe lymphopenia in peripheral organs. HDAC7-deficient pro-B cells exhibit cell lineage promiscuity, expressing myeloid and T lymphocyte genes. In wild-type B cells HDAC7 is recruited to myocyte enhancer factor 2C (MEFC2) binding sites located at the promoters of macrophage and T lymphocyte genes. Our results demonstrate that HDAC7 is a bona fide transcriptional repressor essential for B cell development.
Project description:Polycomb repressive complexes 1 and 2 (PRC1 and 2) repress lineage inappropriate genes during development to maintain proper cellular identities. To reveal the function of a variant PRC1 containing PCGF1 (PCGF1-PRC1), we prepared PCGF1 interacting proteins by immunoprecipitation and characterized them by LC-MS/MS.
Project description:In the immune system HDAC7 is expressed in T cells where it regulates the expression of key genes for T cell development and function. Here we report that HDAC7 is also highly expressed in B cell precursors, where it is recruited by MEF2C to repress the activity of key genes for myeloid cell function. While HDAC7 is down-regulated during the conversion of pre-B cells into macrophages, re-expression of HDAC7 interferes with both the acquisition of the myeloid gene transcriptional program and macrophage specific cell functions. Thus, HDAC7 is a novel transcriptional repressor of lineage inappropriate genes in B cells.
Project description:Polycomb repressive complexes 1 and 2 (PRC1 and 2) repress lineage inappropriate genes during development to maintain proper cellular identities. To reveal the function of a variant PRC1 containing PCGF1 (PCGF1-PRC1), we prepared PCGF1 interacting proteins by immunoprecipitation and characterized them by LC-MS/MS.
Project description:The H3K4me2/3 histone demethylase Jarid1b (Kdm5b/Plu1) is dispensable for embryonic stem cell (ESC) self-renewal, but essential for ESC differentiation along the neural lineage. During neural differentiation, Jarid1b depleted ESCs fail to efficiently silence lineage-inappropriate genes, specifically stem and germ cell genes. Our results delineate an essential role for Jarid1b-mediated transcriptional control during ESC differentiation. Control (LKOScr) or Jarid1b knockdown (LKOJarid1b) mouse ES cells were used.Each experiment was performed in triplicates.
Project description:The generation of B cells is a complex process requiring several cellular transitions, including cell commitment and differentiation, that are tightly controlled by the action of linage-specific transcription factors. Proper transcriptional control to establish the genetic programs characteristic of each cellular stage is essential for the correct development of B lymphocytes. In fact, deregulation of these particular transcriptional programs may result in a block in B cell maturation, contributing to the development of hematological malignancies such as leukemia and lymphoma. In this experiments, We study the HDAC7 expression levels in pro-B-ALL and Burkitt lymphoma. SD-1 Tet-On-Tight-HDAC7 or SD-1 cells were treated or not for 24 hours with doxycycline. We compare the effects in gene expression between the different situations (in presence or in absence of doxycycline)
Project description:Histone deacetylase 7 (HDAC7) is highly expressed in CD4+/CD8+ thymocytes and functions as a signal-dependent repressor of gene transcription during T cell development. In this study, we express HDAC7 mutant proteins in a T cell line and use DNA microarrays to identify transcriptional targets of HDAC7 in T cells. Gene expression changes are compared to differential gene expression profiles associated with positive and negative thymic selection. This analysis reveals that HDAC7 regulates an extensive set of genes that are differentially expressed during both positive and negative thymic selection. Many of these genes play important functional roles in positive and negative selection, primarily via coupling between antigen receptor and downstream signaling events. Keywords: microarray gene expression profiling, comparison of perturbation of HDAC7 gene function with differential expression during thymic selection