Project description:PU.1 (encoded by Spi1), an ETS-family transcription factor with many hematopoietic roles, is highly expressed in the earliest intrathymic T cell progenitors but must be downregulated during T-lineage commitment. Transcription factors Runx1 and GATA3 have been implicated in this Spi1 repression, but the basis of the timing was unknown. We show that increasing Runx1 and/or GATA3 downregulates Spi1 expression in pro-T cells, while deletion of these factors after Spi1 downregulation reactivates its expression. Leveraging the stage-specificities of repression and transcription factor binding revealed an unconventional but functional site in Spi1 intron 2. Acute Cas9-mediated deletion or disruption of the Runx and GATA motifs in this element reactivates silenced Spi1 expression in a pro-T cell line, substantially more than disruption of other candidate elements, and counteracts the repression of Spi1 in primary pro-T cells during commitment. Thus, Runx1 and GATA3 work stage-specifically through an intronic silencing element in mouse Spi1 to control strength and maintenance of Spi1 repression during T-lineage commitment.
Project description:Fibroblasts are polymorphic cells with pleiotropic roles in organ morphogenesis, tissue homeostasis and immune responses. In fibrotic diseases, fibroblasts synthesize abundant amounts of extracellular matrix which lead to scaring and organ failure. In sharp contrast, the hallmark feature of fibroblasts in arthritis is matrix degradation by the release of metalloproteinases and degrading enzymes, and subsequent tissue destruction. The mechanisms driving these functionally opposing pro-fibrotic and pro-inflammatory phenotypes of fibroblasts are enigmatic. We have compared resting, fibrotic, and inflammatory fibroblasts; PU.1 was overexpressed in dermal fibroblasts and compared to scr-transfected controls. Fibrotic fibroblasts isolated from the skin of patients with systemic sclerosis were treated with PU.1 inhibitor and compared to untreated fibrotic fibroblasts and respective healthy controls. Through this, we identified the transcription factor PU.1 as an essential orchestrator of the pro-fibrotic gene expression program. The interplay between transcriptional and post-transcriptional mechanisms which normally control PU.1 expression is perturbed in fibrotic diseases such as pulmonary fibrosis, systemic sclerosis, liver cirrhosis, kidney fibrosis and chronic graft-versus-host disease, resulting in upregulation of PU.1, the induction of fibrosis-associated gene sets, and a phenotypic switch in matrix-producing pro-fibrotic fibroblasts. In contrast, inactivation of PU.1 disrupts the fibrotic network and enables re-programming of fibrotic fibroblasts into resting fibroblasts with regression of fibrosis in different organs. Targeting of PU.1 may thus represent a novel therapeutic approach for the treatment of a wide range of fibrotic diseases.
Project description:The Ets family transcription factor PU.1 is essential for the development and maintenance of several hematopoietic lineages. In the thymus, PU.1 is expressed only in the early ETP/DN1, DN2a and DN2b stages of development. While PU.1 deletion in multipotent precursors leads to a complete block in T-cell development its function in the intrathymic stages in which it is expressed remains undetermined. The goal of this expression profiling study was to determine if PU.1 regulates the expression of T-lineage genes during the early stages of development. To do this, we generated the PU.1-Eng construct which expresses a fusion protein containing the DNA binding ETS domain of PU.1 (aas 159-260) fused to the obligate repressor domain (aas 1-298) of the Drosophila engrailed protein. The PU.1-ETS construct only expresses the ETS domain of PU.1 (aas 159-260) and serves as a control. Fetal liver precursors were isolated from e14.5 embryos and co-cultured with OP9-DL1 cells in the presence of IL-7 and Flt3L (5 ng/ml each) for 4 days to obtain FLDN1, DN2a and DN2b cells. These were infected with vector only, PU.1-ETS and the PU.1-Eng constructs and DN2 cells were sorted after 20 hours of infection. Total RNA was isolated from these cells and polyA+ fraction was used to prepare libraries for high throughput sequencing. Libraries prepared from 2 independent sets of samples were subjected to non-strand specific single-end sequencing. Two sets of samples generated from fetal liver precursor derived DN2 cells expressing PU.1-ETS and PU.1-Eng constructs were used for expression profiling. The LZRS retroviral vector, without any insert, was used to generate the vector control dataset.
Project description:Pulmonary fibrosis (PF) is a terminal lung disease characterized by fibroblast proliferation, accumulation of extracellular matrix accumulation, inflammatory damage, and tissue structure destruction. The pathogenesis of this disease, especiallyparticularly idiopathic pulmonary fibrosis (IPF), is still remains unknown. Macrophages play a significant rolemajor roles in organ fibrosis diseases, including pulmonary fibrosis. The phenotype and polarization of macrophages are closely associated with the process of pulmonary fibrosis. A new direction in drug research on for antipulmonary fibrosis is focuseds on developing drugs that maintain the stability of the pulmonary microenvironment. Here, tThrough bioinformatics analysis and experiments involving bleomycininduced pulmonary fibrosis in mice, we confirmed the importance of macrophage polarization in IPF. The analysis revealed that macrophage polarization in IPF involves a change in the phenotypice spectrum. Furthermore, the experiments demonstrated showed high expression of M2-type macrophage-related-associated biomarkers and inducible nitric oxide synthase, thus indicating an imbalance in M1/M2 polarization of pulmonary macrophages in mice with pulmonary fibrosis. Our investigation revealed that the ethyl acetate extract (HG2) obtained from the roots of Prismatomeris connataPrismatomeris connata Y. Z. Ruan exhibits therapeutic efficacy against bleomycin-induced pulmonary fibrosis. HG2 demonstrates the ability to modulates macrophage polarization, alterations in the TGF‐β/Smads pSmad pathway, and downstream protein expression in the context of pulmonary fibrosis. Drawing upon On the basis of our findings, we believe that HG2 exhibits has potential as a novel component of traditional Chinese medicine component for treating pulmonary fibrosis.
Project description:The Spi1/ Pu.1 transcription factor plays a crucial role in myeloid cell development across many species. Several Spi1 target genes have been identified so far, yet the Spi1-dependent gene group remains largely unknown. To identify novel genes downstream of Spi1 we employed a microarray strategy using zebrafish embryos. We established the gene group down-regulated upon spi1 knockdown while simultaneously enriched in FACS-sorted embryonic myeloid cells of a spi1:GFP transgenic line, thus representing putative myeloid-specific Spi1 target genes. This gene group contained all previously identified Spi1-dependent zebrafish genes, confirming the validity of the approach, as well as novel immune-related genes. Colocalization studies with neutrophil and macrophage markers revealed that genes cxcr3.2, mpeg1, ptpn6 and mfap4 were expressed specifically in early embryonic macrophages. The analysis of adult zebrafish hematopoietic tissue showed that genes mfap4 and mpeg1 remained macrophage specific within the myeloid fraction throughout zebrafish life. We also demonstrated that gene cxcr3.2, coding for chemokine receptor 3.2, functions in macrophage migration to the site of bacterial infection. These results establish a myeloid-specific gene group dependent on Spi1 in zebrafish and identify novel early macrophage-specific marker genes, which will facilitate further studies of macrophage development and innate immune function.
Project description:: Although vascular dysfunction is a hallmark of chronic aging-associated diseases, including idiopathic pulmonary fibrosis, the role of the pulmonary vasculature to lung repair versus lung fibrosis is not fully understood. We identified the endothelial transcription factor ETS-related gene (ERG) as an orchestrator of vascular homeostasis and repair following lung injury. To evaluate whether loss of endothelial ERG influences the activation of neighboring naïve lung fibroblasts, we collected the conditioned media (CM) generated by control- and ERG-silenced human lung endothelial cells (ECs) and we applied them to normal human lung fibroblasts. We found that CM from ERG-silenced human lung ECs strongly promoted human lung fibroblast activation and enhanced the effect of the fibrogenic mediator TGF. In support of these results, analysis of CM using nanoscale liquid chromatography coupled to tandem mass spectrometry (nano LC-MS/MS) revealed increased secretion of numerous pro-inflammatory and pro-fibrogenic mediators by ERG-silenced human lung ECs in comparison to control-silenced human lung ECs.
Project description:The Ets family transcription factor PU.1 is essential for the development and maintenance of several hematopoietic lineages. In the thymus, PU.1 is expressed only in the early ETP/DN1, DN2a and DN2b stages of development. While PU.1 deletion in multipotent precursors leads to a complete block in T-cell development its function in the intrathymic stages in which it is expressed remains undetermined. The goal of this expression profiling study was to determine if PU.1 regulates the expression of T-lineage genes during the early stages of development. To do this, we generated the PU.1-Eng construct which expresses a fusion protein containing the DNA binding ETS domain of PU.1 (aas 159-260) fused to the obligate repressor domain (aas 1-298) of the Drosophila engrailed protein. The PU.1-ETS construct only expresses the ETS domain of PU.1 (aas 159-260) and serves as a control. Fetal liver precursors were isolated from e14.5 embryos and co-cultured with OP9-DL1 cells in the presence of IL-7 and Flt3L (5 ng/ml each) for 4 days to obtain FLDN1, DN2a and DN2b cells. These were infected with vector only, PU.1-ETS and the PU.1-Eng constructs and DN2 cells were sorted after 20 hours of infection. Total RNA was isolated from these cells and polyA+ fraction was used to prepare libraries for high throughput sequencing. Libraries prepared from 2 independent sets of samples were subjected to non-strand specific single-end sequencing.
Project description:PU.1 is an Ets family transcription factor that is essential for the differentiation of both myeloid and lymphoid cells. PU.1 is down-regulated in classical Hodgkin lymphoma cells via methylation of the PU.1 promoter. To evaluate whether down-regulation of PU.1 is essential for the growth of cHL cells, we generated L428 derived cell lines conditionally express PU.1 by tet-off system (designated L428tetPU.1). Conditonally expressed PU.1 by tetracycline removal induced complete growth arrest and apoptosis in L428 cells. To elucidate the mechanisms underlying cell cycle arrest and apoptosis induced by PU.1, we compared gene expression profiles of L428tetPU.1 cells 0, 1 and 3 days after PU.1 induction, by DNA microarray. We extracted total RNA from L428tetPU.1 cells 0, 1 and 3 days after PU.1 induction by tetracycline removal. We compared gene expression profiles of KL428tetPU.1 cells 0, 1 and 3 days after PU.1 induction using DNA microarray analysis. 4 independent experiments were performed with each RNA samples.