ABSTRACT
The APOE4 allele is the strongest genetic risk factor for late-onset Alzheimer's disease (AD). The contribution of microglial APOE4 to AD pathogenesis is unknown, although APOE has the most enriched gene expression in neurodegenerative microglia (MGnD). Here, we show in mice and humans a negative role of microglial APOE4 in the induction of the MGnD response to neurodegeneration. Deletion of microglial APOE4 restores the MGnD phenotype associated with neuroprotection in P301S tau transgenic mice and decreases pathology in APP/PS1 mice. MGnD-astrocyte cross-talk associated with ß-amyloid (Aß) plaque encapsulation and clearance are mediated via LGALS3 signaling following microglial APOE4 deletion. In the brains of AD donors carrying the APOE4 allele, we found a sex-dependent reciprocal induction of AD risk factors associated with suppression of MGnD genes in females, including LGALS3, compared to individuals homozygous for the APOE3 allele. Mechanistically, APOE4-mediated induction of ITGB8-transforming growth factor-ß (TGFß) signaling impairs the MGnD response via upregulation of microglial homeostatic checkpoints, including Inpp5d, in mice. Deletion of Inpp5d in microglia restores MGnD-astrocyte cross-talk and facilitates plaque clearance in APP/PS1 mice. We identify the microglial APOE4-ITGB8-TGFß pathway as a negative regulator of microglial response to AD pathology, and restoring the MGnD phenotype via blocking ITGB8-TGFß signaling provides a promising therapeutic intervention for AD.
Subject(s)
Alzheimer Disease , Female , Mice , Humans , Animals , Alzheimer Disease/genetics , Alzheimer Disease/pathology , Apolipoprotein E4/genetics , Apolipoprotein E4/metabolism , Microglia/metabolism , Galectin 3/genetics , Galectin 3/metabolism , Amyloid beta-Peptides/metabolism , Mice, Transgenic , Disease Models, AnimalABSTRACT
Tumor-infiltrating myeloid cells (TIMs) comprise monocytes, macrophages, dendritic cells, and neutrophils, and have emerged as key regulators of cancer growth. These cells can diversify into a spectrum of states, which might promote or limit tumor outgrowth but remain poorly understood. Here, we used single-cell RNA sequencing (scRNA-seq) to map TIMs in non-small-cell lung cancer patients. We uncovered 25 TIM states, most of which were reproducibly found across patients. To facilitate translational research of these populations, we also profiled TIMs in mice. In comparing TIMs across species, we identified a near-complete congruence of population structures among dendritic cells and monocytes; conserved neutrophil subsets; and species differences among macrophages. By contrast, myeloid cell population structures in patients' blood showed limited overlap with those of TIMs. This study determines the lung TIM landscape and sets the stage for future investigations into the potential of TIMs as immunotherapy targets.
Subject(s)
Carcinoma, Non-Small-Cell Lung/immunology , Dendritic Cells/immunology , Lung Neoplasms/immunology , Macrophages/immunology , Monocytes/immunology , Neutrophils/immunology , Animals , Base Sequence , Carcinoma, Non-Small-Cell Lung/pathology , Cell Line, Tumor , Gene Expression Profiling , Humans , Lung/immunology , Lung/pathology , Lung Neoplasms/pathology , Male , Mice , Mice, Inbred C57BL , Sequence Analysis, RNAABSTRACT
Point mutations within the TERT promoter are the most recurrent somatic noncoding mutations identified across different cancer types, including glioblastoma, melanoma, hepatocellular carcinoma, and bladder cancer. They are most abundant at -146C > T and -124C > T, and rarer at -57A > C, with the latter originally described as a familial case, but subsequently shown also to occur somatically. All three mutations create de novo E26-specific (ETS) binding sites and result in activation of the TERT gene, allowing cancer cells to achieve replicative immortality. Here, we used a systematic proteomics screen to identify transcription factors preferentially binding to the -146C > T, -124C > T, and -57A > C mutations. Although we confirmed binding of multiple ETS factors to the mutant -146C > T and -124C > T sequences, we identified E4F1 as a -57A > C-specific binder and ZNF148 as a TERT wild-type (WT) promoter binder that showed reduced interaction with the -124C > T allele. Both proteins are activating transcription factors that bind specifically to the -57A > C and WT (at position 124) TERT promoter sequence in corresponding cell lines, and up-regulate TERT transcription and telomerase activity. Our work describes new regulators of TERT gene expression with possible roles in cancer.
ABSTRACT
BACKGROUND: Although hypomethylating agents are currently used to treat patients with cancer, whether they can also reactivate and up-regulate oncogenes is not well elucidated. METHODS: We examined the effect of hypomethylating agents on SALL4, a known oncogene that plays an important role in myelodysplastic syndrome and other cancers. Paired bone marrow samples that were obtained from two cohorts of patients with myelodysplastic syndrome before and after treatment with a hypomethylating agent were used to explore the relationships among changes in SALL4 expression, treatment response, and clinical outcome. Leukemic cell lines with low or undetectable SALL4 expression were used to study the relationship between SALL4 methylation and expression. A locus-specific demethylation technology, CRISPR-DNMT1-interacting RNA (CRISPR-DiR), was used to identify the CpG island that is critical for SALL4 expression. RESULTS: SALL4 up-regulation after treatment with hypomethylating agents was observed in 10 of 25 patients (40%) in cohort 1 and in 13 of 43 patients (30%) in cohort 2 and was associated with a worse outcome. Using CRISPR-DiR, we discovered that demethylation of a CpG island within the 5' untranslated region was critical for SALL4 expression. In cell lines and patients, we confirmed that treatment with a hypomethylating agent led to demethylation of the same CpG region and up-regulation of SALL4 expression. CONCLUSIONS: By combining analysis of patient samples with CRISPR-DiR technology, we found that demethylation and up-regulation of an oncogene after treatment with a hypomethylating agent can indeed occur and should be further studied. (Funded by Associazione Italiana per la Ricerca sul Cancro and others.).
Subject(s)
Antineoplastic Agents , Demethylation , Myelodysplastic Syndromes , Oncogenes , Up-Regulation , Antineoplastic Agents/pharmacology , Antineoplastic Agents/therapeutic use , Clustered Regularly Interspaced Short Palindromic Repeats , Demethylation/drug effects , Humans , Myelodysplastic Syndromes/drug therapy , Myelodysplastic Syndromes/genetics , Neoplasms/drug therapy , Neoplasms/genetics , Oncogenes/drug effects , Oncogenes/physiology , Transcription Factors/biosynthesis , Transcription Factors/genetics , Transcription Factors/metabolism , Up-Regulation/drug effectsABSTRACT
Adenosine-to-inosine RNA editing, which is catalyzed by adenosine deaminases acting on RNA (ADAR) family of enzymes, ADAR1 and ADAR2, has been shown to contribute to multiple cancers. However, other than the chronic myeloid leukemia blast crisis, relatively little is known about its role in other types of hematological malignancies. Here, we found that ADAR2, but not ADAR1 and ADAR3, was specifically downregulated in the core-binding factor (CBF) acute myeloid leukemia (AML) with t(8;21) or inv(16) translocations. In t(8;21) AML, RUNX1-driven transcription of ADAR2 was repressed by the RUNX1-ETO additional exon 9a fusion protein in a dominant-negative manner. Further functional studies confirmed that ADAR2 could suppress leukemogenesis specifically in t(8;21) and inv16 AML cells dependent on its RNA editing capability. Expression of 2 exemplary ADAR2-regulated RNA editing targets coatomer subunit α and component of oligomeric Golgi complex 3 inhibits the clonogenic growth of human t(8;21) AML cells. Our findings support a hitherto, unappreciated mechanism leading to ADAR2 dysregulation in CBF AML and highlight the functional relevance of loss of ADAR2-mediated RNA editing to CBF AML.
Subject(s)
Core Binding Factors , Leukemia, Myeloid, Acute , Humans , Down-Regulation , Core Binding Factors/metabolism , Core Binding Factor Alpha 2 Subunit/genetics , Core Binding Factor Alpha 2 Subunit/metabolism , RNA Editing , Adenosine Deaminase/genetics , Adenosine Deaminase/metabolism , Leukemia, Myeloid, Acute/genetics , Adenosine/metabolismABSTRACT
Immunotherapy has emerged as a mainstay in cancer therapy, yet its efficacy is constrained by the risk of immune-related adverse events. In this study, we present a nanoparticle-based delivery system that enhances the therapeutic efficacy of immunomodulatory ligands while concurrently limiting systemic toxicity. We demonstrate that extracellular vesicles (EVs), lipid bilayer enclosed particles released by cells, can be efficiently engineered via inverse electron demand Diels-Alder (iEDDA)-mediated conjugation to display multiple immunomodulatory ligands on their surface. Display of immunomodulatory ligands on the EV surface conferred substantial enhancements in signaling efficacy, particularly for tumor necrosis factor receptor superfamily (TNFRSF) agonists, where the EV surface display served as an alternative FcγR-independent approach to induce ligand multimerization and efficient receptor crosslinking. EVs displaying a complementary combination of immunotherapeutic ligands were able to shift the tumor immune milieu toward an anti-tumorigenic phenotype and significantly suppress tumor burden and increase survival in multiple models of metastatic cancer to a greater extent than an equivalent dose of free ligands. In summary, we present an EV-based delivery platform for cancer immunotherapeutic ligands that facilitates superior anti-tumor responses at significantly lower doses with fewer side effects than is possible with conventional delivery approaches.
ABSTRACT
The phosphoinositide 3-kinase (PI3K) pathway represents the most hyperactivated oncogenic pathway in triple-negative breast cancer (TNBC), a highly aggressive tumor subtype encompassing â¼15% of breast cancers and which possesses no targeted therapeutics. Despite critical contributions of its signaling arms to disease pathogenesis, PI3K pathway inhibitors have not achieved expected clinical responses in TNBC, owing largely to a still-incomplete understanding of the compensatory cascades that operate downstream of PI3K. Here, we investigated the contributions of long noncoding RNAs (lncRNAs) to PI3K activities in clinical and experimental TNBC and discovered a prominent role for LINC01133 as a PI3K-AKT signaling effector. We found that LINC01133 exerted protumorigenic roles in TNBC and that it governed a previously undescribed mTOR Complex 2 (mTORC2)-dependent pathway that activated AKT in a PI3K-independent manner. Mechanistically, LINC01133 induced the expression of the mTORC2 component PROTOR1/PRR5 by competitively coupling away its negative messenger RNA (mRNA) regulator, the heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNPA2B1). PROTOR1/PRR5 in turn was sufficient and necessary for LINC01133-triggered functions, casting previously unappreciated roles for this Rictor-binding protein in cellular signaling and growth. Notably, LINC01133 antagonism undermined cellular growth, and we show that the LINC01133-PROTOR1/PRR5 pathway was tightly associated with TNBC poor patient survival. Altogether, our findings uncovered a lncRNA-driven signaling shunt that acts as a critical determinant of malignancy downstream of the PI3K pathway and as a potential RNA therapeutic target in clinical TNBC management.
Subject(s)
RNA, Long Noncoding , Triple Negative Breast Neoplasms , Humans , RNA, Long Noncoding/genetics , RNA, Long Noncoding/metabolism , Triple Negative Breast Neoplasms/metabolism , Phosphatidylinositol 3-Kinases/genetics , Phosphatidylinositol 3-Kinases/metabolism , Phosphatidylinositol 3-Kinase/metabolism , Proto-Oncogene Proteins c-akt/genetics , Proto-Oncogene Proteins c-akt/metabolism , Cell Proliferation/genetics , Phosphoinositide-3 Kinase Inhibitors , Mechanistic Target of Rapamycin Complex 2/metabolism , RNA, Messenger , Heterogeneous-Nuclear Ribonucleoproteins , Cell Line, TumorABSTRACT
The oncogenic transcription factor TAL1/SCL induces an aberrant transcriptional program in T-cell acute lymphoblastic leukemia (T-ALL) cells. However, the critical factors that are directly activated by TAL1 and contribute to T-ALL pathogenesis are largely unknown. Here, we identified AT-rich interactive domain 5B (ARID5B) as a collaborating oncogenic factor involved in the transcriptional program in T-ALL. ARID5B expression is down-regulated at the double-negative 2-4 stages in normal thymocytes, while it is induced by the TAL1 complex in human T-ALL cells. The enhancer located 135 kb upstream of the ARID5B gene locus is activated under a superenhancer in T-ALL cells but not in normal T cells. Notably, ARID5B-bound regions are associated predominantly with active transcription. ARID5B and TAL1 frequently co-occupy target genes and coordinately control their expression. ARID5B positively regulates the expression of TAL1 and its regulatory partners. ARID5B also activates the expression of the oncogene MYC Importantly, ARID5B is required for the survival and growth of T-ALL cells, and forced expression of ARID5B in immature thymocytes results in thymus retention, differentiation arrest, radioresistance, and tumor formation in zebrafish. Our results indicate that ARID5B reinforces the oncogenic transcriptional program by positively regulating the TAL1-induced regulatory circuit and MYC in T-ALL, thereby contributing to T-cell leukemogenesis.
Subject(s)
Carcinogenesis/genetics , DNA-Binding Proteins/metabolism , Gene Expression Regulation, Neoplastic , T-Cell Acute Lymphocytic Leukemia Protein 1/metabolism , Transcription Factors/metabolism , Animals , Cell Line, Tumor , Cell Survival/genetics , DNA-Binding Proteins/genetics , Enhancer Elements, Genetic/genetics , Gene Expression Profiling , Genes, myc/genetics , HEK293 Cells , Humans , Precursor T-Cell Lymphoblastic Leukemia-Lymphoma , Protein Binding , Protein Domains/genetics , Thymocytes/metabolism , Thymus Gland/growth & development , Transcription Factors/genetics , Transcriptional Activation/genetics , ZebrafishABSTRACT
The architecture of chromatin regulates eukaryotic cell states by controlling transcription factor access to sites of gene regulation. Here we describe a dual transposase-peroxidase approach, integrative DNA and protein tagging (iDAPT), which detects both DNA (iDAPT-seq) and protein (iDAPT-MS) associated with accessible regions of chromatin. In addition to direct identification of bound transcription factors, iDAPT enables the inference of their gene regulatory networks, protein interactors and regulation of chromatin accessibility. We applied iDAPT to profile the epigenomic consequences of granulocytic differentiation of acute promyelocytic leukemia, yielding previously undescribed mechanistic insights. Our findings demonstrate the power of iDAPT as a platform for studying the dynamic epigenomic landscapes and their transcription factor components associated with biological phenomena and disease.
Subject(s)
Chromatin/metabolism , DNA/genetics , Gene Expression Regulation/genetics , Histones/metabolism , Leukemia, Promyelocytic, Acute/genetics , Gene Regulatory Networks , Humans , Leukemia, Promyelocytic, Acute/pathology , Transcription Factors/metabolismABSTRACT
Chromatin immunoprecipitation coupled with sequencing (ChIP-seq) is a technique used to identify protein-DNA interaction sites through antibody pull-down, sequencing and analysis; with enrichment 'peak' calling being the most critical analytical step. Benchmarking studies have consistently shown that peak callers have distinct selectivity and specificity characteristics that are not additive and seldom completely overlap in many scenarios, even after parameter optimization. We therefore developed ChIP-AP, an integrated ChIP-seq analysis pipeline utilizing four independent peak callers, which seamlessly processes raw sequencing files to final result. This approach enables (1) better gauging of peak confidence through detection by multiple algorithms, and (2) more thoroughly surveys the binding landscape by capturing peaks not detected by individual callers. Final analysis results are then integrated into a single output table, enabling users to explore their data by applying selectivity and sensitivity thresholds that best address their biological questions, without needing any additional reprocessing. ChIP-AP therefore presents investigators with a more comprehensive coverage of the binding landscape without requiring additional wet-lab observations.
Subject(s)
Chromatin Immunoprecipitation Sequencing , Oligonucleotide Array Sequence Analysis/methods , Sequence Analysis, DNA/methods , Algorithms , Benchmarking , Cell Line , Chromatin Immunoprecipitation , Software , Transcription FactorsABSTRACT
Epidermal Growth Factor Receptor (EGFR) enacts major roles in the maintenance of epithelial tissues. However, when EGFR signaling is altered, it becomes the grand orchestrator of epithelial transformation, and hence one of the most world-wide studied tyrosine kinase receptors involved in neoplasia, in several tissues. In the last decades, EGFR-targeted therapies shaped the new era of precision-oncology. Despite major advances, the dream of converting solid tumors into a chronic disease is still unfulfilled, and long-term remission eludes us. Studies investigating the function of this protein in solid malignancies have revealed numerous ways how tumor cells dysregulate EGFR function. Starting from preclinical models (cell lines, organoids, murine models) and validating in clinical specimens, EGFR-related oncogenic pathways, mechanisms of resistance, and novel avenues to inhibit tumor growth and metastatic spread enriching the therapeutic portfolios, were identified. Focusing on non-small cell lung cancer (NSCLC), where EGFR mutations are major players in the adenocarcinoma subtype, we will go over the most relevant discoveries that led us to understand EGFR and beyond, and highlight how they revolutionized cancer treatment by expanding the therapeutic arsenal at our disposal.
Subject(s)
Carcinoma, Non-Small-Cell Lung , Lung Neoplasms , Humans , Mice , Animals , Carcinoma, Non-Small-Cell Lung/genetics , Lung Neoplasms/genetics , Protein Kinase Inhibitors/pharmacology , Drug Resistance, Neoplasm/genetics , Mutation , ErbB Receptors/genetics , ErbB Receptors/metabolism , Signal TransductionABSTRACT
Histone modifications play crucial roles in transcriptional activation, and aberrant epigenetic changes are associated with oncogenesis. Lysine (K) acetyltransferases 5 (TIP60, also known as KAT5) is reportedly implicated in cancer development and maintenance, although its function in lung cancer remains controversial. Here we demonstrate that TIP60 knockdown in non-small cell lung cancer cell lines decreased tumor cell growth, migration, and invasion. Furthermore, analysis of a mouse lung cancer model with lung-specific conditional Tip60 knockout revealed suppressed tumor formation relative to controls, but no apparent effects on normal lung homeostasis. RNA-seq and ChIP-seq analyses of inducible TIP60 knockdown H1975 cells relative to controls revealed transglutaminase enzyme (TGM5) as downstream of TIP60. Investigation of a connectivity map database identified several candidate compounds that decrease TIP60 mRNA, one that suppressed tumor growth in cell culture and in vivo. In addition, TH1834, a TIP60 acetyltransferase inhibitor, showed comparable antitumor effects in cell culture and in vivo. Taken together, suppression of TIP60 activity shows tumor-specific efficacy against lung cancer, with no overt effect on normal tissues. Our work suggests that targeting TIP60 could be a promising approach to treating lung cancer.
Subject(s)
Carcinoma, Non-Small-Cell Lung , Lung Neoplasms , Animals , Mice , Carcinogenesis/genetics , Carcinoma, Non-Small-Cell Lung/genetics , Cell Transformation, Neoplastic/genetics , Histone Acetyltransferases/genetics , Histone Acetyltransferases/metabolism , Lung Neoplasms/genetics , HumansABSTRACT
The core binding factor composed of CBFß and RUNX subunits plays a critical role in most hematopoietic lineages and is deregulated in acute myeloid leukemia (AML). The fusion oncogene CBFß-SMMHC expressed in AML with the chromosome inversion inv(16)(p13q22) acts as a driver oncogene in hematopoietic stem cells and induces AML. This review focuses on novel insights regarding the molecular mechanisms involved in CBFß-SMMHC-driven leukemogenesis and recent advances in therapeutic approaches to target CBFß-SMMHC in inv(16) AML.
Subject(s)
Cell Transformation, Neoplastic/genetics , Chromosome Inversion , Chromosomes, Human, Pair 16/genetics , Core Binding Factor beta Subunit/genetics , Immunotherapy/methods , Leukemia, Myeloid, Acute/drug therapy , Molecular Targeted Therapy , Myosin Heavy Chains/genetics , Oncogene Proteins, Fusion/antagonists & inhibitors , Animals , Antineoplastic Agents, Immunological/therapeutic use , Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Chromosomes, Human, Pair 16/ultrastructure , Combined Modality Therapy , Core Binding Factor Alpha 2 Subunit/deficiency , Core Binding Factor Alpha 2 Subunit/metabolism , Core Binding Factor beta Subunit/physiology , Forecasting , Gemtuzumab/therapeutic use , Gene Expression Regulation, Leukemic , Gene Knock-In Techniques , Hematopoiesis/drug effects , Hematopoiesis/genetics , Humans , Leukemia, Myeloid, Acute/genetics , Mice , Neoplastic Stem Cells/drug effects , Neoplastic Stem Cells/metabolism , Neoplastic Stem Cells/pathology , Oncogene Proteins, Fusion/genetics , Oncogene Proteins, Fusion/physiology , T-Lymphocytes/immunology , Xenograft Model Antitumor AssaysABSTRACT
The mechanism underlying cell type-specific gene induction conferred by ubiquitous transcription factors as well as disruptions caused by their chimeric derivatives in leukemia is not well understood. Here, we investigate whether RNAs coordinate with transcription factors to drive myeloid gene transcription. In an integrated genome-wide approach surveying for gene loci exhibiting concurrent RNA and DNA interactions with the broadly expressed Runt-related transcription factor 1 (RUNX1), we identified the long noncoding RNA (lncRNA) originating from the upstream regulatory element of PU.1 (LOUP). This myeloid-specific and polyadenylated lncRNA induces myeloid differentiation and inhibits cell growth, acting as a transcriptional inducer of the myeloid master regulator PU.1. Mechanistically, LOUP recruits RUNX1 to both the PU.1 enhancer and the promoter, leading to the formation of an active chromatin loop. In t(8;21) acute myeloid leukemia (AML), wherein RUNX1 is fused to ETO, the resulting oncogenic fusion protein, RUNX1-ETO, limits chromatin accessibility at the LOUP locus, causing inhibition of LOUP and PU.1 expression. These findings highlight the important role of the interplay between cell-type-specific RNAs and transcription factors, as well as their oncogenic derivatives in modulating lineage-gene activation and raise the possibility that RNA regulators of transcription factors represent alternative targets for therapeutic development.
Subject(s)
Core Binding Factor Alpha 2 Subunit/genetics , Leukemia, Myeloid, Acute/genetics , Oncogene Proteins, Fusion/genetics , RNA, Long Noncoding/genetics , RUNX1 Translocation Partner 1 Protein/genetics , Cell Line, Tumor , Gene Expression Regulation, Leukemic , Humans , Transcriptional ActivationABSTRACT
PURPOSE OF REVIEW: Advancements in the next-generation sequencing technologies have identified rare transcripts of long noncoding RNAs (lncRNAs) in the genome of cancers, including in acute myeloid leukemia (AML). The purpose of this review is to highlight the contribution of lncRNAs in AML pathogenesis, prognosis, and chemoresistance. RECENT FINDINGS: Several studies have recently reported that deregulated lncRNAs are novel key players in the development of AML and are associated with AML pathophysiology and may serve as prognostic indicators. A few aberrantly expressed lncRNAs that correlated with the recurrent genetic mutations in AML such as NPM1 and RUNX1 have recently been characterized. Moreover, a few lncRNAs in MLL-rearranged leukemia have been described. Additionally, the involvement of lncRNAs in AML chemoresistance has been postulated. SUMMARY: Investigating the functional roles of the noncoding regions including lncRNAs, may provide novel insights into the pathophysiology, refine the prognostic schema, and provide novel therapeutic treatment strategies in AML.
Subject(s)
Leukemia, Myeloid, Acute , RNA, Long Noncoding , High-Throughput Nucleotide Sequencing , Humans , Leukemia, Myeloid, Acute/diagnosis , Leukemia, Myeloid, Acute/drug therapy , Leukemia, Myeloid, Acute/genetics , Mutation , Prognosis , RNA, Long Noncoding/geneticsABSTRACT
The canonical Wnt signaling pathway is mediated by interaction of ß-catenin with the T-cell factor/lymphoid enhancer-binding factor (TCF/LEF) transcription factors and subsequent transcription activation of Wnt-target genes. In the hematopoietic system, the function of the pathway has been mainly investigated by rather unspecific genetic manipulations of ß-catenin that yielded contradictory results. Here, we used a mouse expressing a truncated dominant negative form of the human TCF4 transcription factor (dnTCF4) that specifically abrogates ß-catenin-TCF/LEF interaction. Disruption of the ß-catenin-TCF/LEF interaction resulted in the accumulation of immature cells and reduced granulocytic differentiation. Mechanistically, dnTCF4 progenitors exhibited downregulation of the Csf3r gene, reduced granulocyte colony-stimulating factor (G-CSF) receptor levels, attenuation of downstream Stat3 phosphorylation after G-CSF treatment, and impaired G-CSF-mediated differentiation. Chromatin immunoprecipitation assays confirmed direct binding of TCF/LEF factors to the promoter and putative enhancer regions of CSF3R. Inhibition of ß-catenin signaling compromised activation of the emergency granulopoiesis program, which requires maintenance and expansion of myeloid progenitors. Consequently, dnTCF4 mice were more susceptible to Candida albicans infection and more sensitive to 5-fluorouracil-induced granulocytic regeneration. Importantly, genetic and chemical inhibition of ß-catenin-TCF/LEF signaling in human CD34+ cells reduced granulocytic differentiation, whereas its activation enhanced myelopoiesis. Altogether, our data indicate that the ß-catenin-TCF/LEF complex directly regulates G-CSF receptor levels, and consequently controls proper differentiation of myeloid progenitors into granulocytes in steady-state and emergency granulopoiesis. Our results uncover a role for the ß-catenin signaling pathway in fine tuning the granulocytic production, opening venues for clinical intervention that require enhanced or reduced production of neutrophils.
Subject(s)
Granulocytes/metabolism , Myelopoiesis , Receptors, Colony-Stimulating Factor/biosynthesis , Signal Transduction , TCF Transcription Factors/metabolism , Transcription Factor 7-Like 2 Protein/metabolism , Up-Regulation , beta Catenin/metabolism , Animals , Candida albicans , Candidiasis/genetics , Candidiasis/metabolism , Mice , Mice, Transgenic , Receptors, Colony-Stimulating Factor/genetics , TCF Transcription Factors/genetics , beta Catenin/geneticsABSTRACT
Hematopoietic stem cells (HSCs) have the potential to replenish the blood system for the lifetime of the organism. Their 2 defining properties, self-renewal and differentiation, are tightly regulated by the epigenetic machineries. Using conditional gene-knockout models, we demonstrated a critical requirement of lysine acetyltransferase 5 (Kat5, also known as Tip60) for murine HSC maintenance in both the embryonic and adult stages, which depends on its acetyltransferase activity. Genome-wide chromatin and transcriptome profiling in murine hematopoietic stem and progenitor cells revealed that Tip60 colocalizes with c-Myc and that Tip60 deletion suppress the expression of Myc target genes, which are associated with critical biological processes for HSC maintenance, cell cycling, and DNA repair. Notably, acetylated H2A.Z (acH2A.Z) was enriched at the Tip60-bound active chromatin, and Tip60 deletion induced a robust reduction in the acH2A.Z/H2A.Z ratio. These results uncover a critical epigenetic regulatory layer for HSC maintenance, at least in part through Tip60-dependent H2A.Z acetylation to activate Myc target genes.
Subject(s)
Cell Self Renewal/genetics , Hematopoietic Stem Cells/cytology , Hematopoietic Stem Cells/metabolism , Lysine Acetyltransferase 5/genetics , Trans-Activators/genetics , Animals , Biomarkers , Cell Cycle , Cell Differentiation/genetics , DNA Damage , Gene Expression Profiling , Gene Expression Regulation , Histones/metabolism , Lysine Acetyltransferase 5/metabolism , Mice , Protein Transport , Trans-Activators/metabolismABSTRACT
The oncogenic transcription factor TAL1 regulates the transcriptional program in T-ALL. ARID5B is one of the critical downstream targets of TAL1, which further activates the oncogenic regulatory circuit in T-ALL cells. Here, we elucidated the molecular functions of the noncoding RNA, ARID5B-inducing enhancer associated long noncoding RNA (ARIEL), in T-ALL pathogenesis. We demonstrated that ARIEL is specifically activated in TAL1 + T-ALL cases, and its expression is associated with ARID5B enhancer activity. ARIEL recruits mediator proteins to the ARID5B enhancer, promotes enhancer-promoter interactions, and activates the expression of ARID5B, thereby positively regulating the TAL1-induced transcriptional program and the MYC oncogene. The TAL1 complex coordinately regulates the expression of ARIEL Knockdown of ARIEL inhibits cell growth and survival of T-ALL cells in culture and blocks disease progression in a murine xenograft model. Our results indicate that ARIEL plays an oncogenic role as an enhancer RNA in T-ALL.
Subject(s)
Carcinogenesis/genetics , Gene Expression Regulation, Leukemic , Precursor T-Cell Lymphoblastic Leukemia-Lymphoma/genetics , RNA, Long Noncoding/genetics , Transcription, Genetic , Animals , Binding Sites , Cell Line, Tumor , Cell Proliferation , Cell Survival/genetics , Chromatin Immunoprecipitation Sequencing , DNA-Binding Proteins/metabolism , Disease Models, Animal , Disease Progression , Enhancer Elements, Genetic , Gene Knockdown Techniques , Gene Targeting , Heterografts , Humans , Mice , Models, Biological , Multiprotein Complexes , Oncogenes , Precursor T-Cell Lymphoblastic Leukemia-Lymphoma/metabolism , Promoter Regions, Genetic , Protein Binding , T-Cell Acute Lymphocytic Leukemia Protein 1/metabolism , Transcription Factors/metabolismABSTRACT
To provide a lifelong supply of blood cells, hematopoietic stem cells (HSCs) need to carefully balance both self-renewing cell divisions and quiescence. Although several regulators that control this mechanism have been identified, we demonstrate that the transcription factor PU.1 acts upstream of these regulators. So far, attempts to uncover PU.1's role in HSC biology have failed because of the technical limitations of complete loss-of-function models. With the use of hypomorphic mice with decreased PU.1 levels specifically in phenotypic HSCs, we found reduced HSC long-term repopulation potential that could be rescued completely by restoring PU.1 levels. PU.1 prevented excessive HSC division and exhaustion by controlling the transcription of multiple cell-cycle regulators. Levels of PU.1 were sustained through autoregulatory PU.1 binding to an upstream enhancer that formed an active looped chromosome architecture in HSCs. These results establish that PU.1 mediates chromosome looping and functions as a master regulator of HSC proliferation.
Subject(s)
Adult Stem Cells/metabolism , Cell Cycle/genetics , Cell Differentiation , Hematopoietic Stem Cells/metabolism , Proto-Oncogene Proteins/genetics , Trans-Activators/genetics , Adult Stem Cells/pathology , Animals , Cell Proliferation , Hematopoietic Stem Cells/pathology , Humans , Mice , Mice, Inbred Strains , Proto-Oncogene Proteins/metabolism , Trans-Activators/metabolismABSTRACT
DNMT3B is known as a de novo DNA methyltransferase. However, its preferential target sites for DNA methylation are largely unknown. Our analysis on ChIP-seq experiment in human embryonic stem cells (hESC) revealed that DNMT3B, mCA and H3K36me3 share the same genomic distribution profile. Deletion of DNMT3B or its histone-interacting domain (PWWP) demolished mCA in hESCs, suggesting that PWWP domain of DNMT3B directs the formation of mCA landscape. In contrast to the common presumption that PWWP guides DNMT3B-mediated mCG deposition, we found that deleting PWWP does not affect the mCG landscape. Nonetheless, DNMT3B knockout led to the formation of 2985 de novo hypomethylated regions at annotated promoter sites. Upon knockout, most of these promoters gain the bivalent marks, H3K4me3 and H3K27me3. We call them spurious bivalent promoters. Gene ontology analysis associated spurious bivalent promoters with development and cell differentiation. Overall, we found the importance of DNMT3B for shaping the mCA landscape and for maintaining the fidelity of the bivalent promoters in hESCs.