The transcription factor C/EBPbeta triggers phosphorylation of the coactivator p300: A new mechanism of cross-talk between transcription factors and coactivators?

AbstractMutations in the transcription factor C/EBPα are found in ~10% of all acute myeloid leukaemia (AML) cases but the contribution of these mutations to leukemogenesis is incompletely understood. We here use a mouse model of granulocyte progenitors expressing conditionally active HoxB8 to assess the cell biological and molecular activity of C/EBPα-mutations associated with human AML. Both N-terminal truncation and C-terminal AML-associated mutations of C/EBPα substantially altered differentiation of progenitors into mature neutrophils in cell culture. Closer analysis of the C/EBPα-K313-duplication showed expansion and prolonged survival of mutant C/EBPα-expressing granulocytes following adoptive transfer into mice. C/EBPα-protein containing the K313-mutation further showed strongly enhanced transcriptional activity compared with the wild-type protein at certain promoters. Analysis of differentially regulated genes in cells overexpressing C/EBPα-K313 indicates a strong correlation with genes regulated by C/EBPα. Analysis of transcription factor enrichment in the differentially regulated genes indicated a strong reliance of SPI1/PU.1, suggesting that despite reduced DNA binding, C/EBPα-K313 is active in regulating target gene expression and acts largely through a network of other transcription factors. Strikingly, the K313 mutation caused strongly elevated expression of C/EBPα-protein, which could also be seen in primary K313 mutated AML blasts, explaining the enhanced C/EBPα activity in K313-expressing cells.

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Transcriptome analyses of cells carrying the Type II Csp231I restriction–modification system reveal cross-talk between two unrelated transcription factors: C protein and the Rac prophage repressor

Nucleic Acids Research ◽

10.1093/nar/gkz665 ◽

2019 ◽

Vol 47 (18) ◽

pp. 9542-9556 ◽

Cited By ~ 1

Author(s):

Alessandro Negri ◽

Marcin Jąkalski ◽

Aleksandra Szczuka ◽

Leszek P Pryszcz ◽

Iwona Mruk

Keyword(s):

Transcription Factor ◽

Gene Transfer ◽

Cross Talk ◽

Dna Cleavage ◽

In Vitro Assays ◽

Type Ii ◽

Modification System ◽

C Protein ◽

Factor C ◽

Restriction Modification

AbstractRestriction-modification (R–M) systems represent an effective mechanism of defence against invading bacteriophages, and are widely spread among bacteria and archaea. In acquiring a Type II R–M system via horizontal gene transfer, the new hosts become more resistant to phage infection, through the action of a restriction endonuclease (REase), which recognizes and cleaves specific target DNAs. To protect the host cell's DNA, there is also a methyltransferase (MTase), which prevents DNA cleavage by the cognate REase. In some R–M systems, the host also accepts a cis-acting transcription factor (C protein), which regulates the counteracting activities of REase and MTase to avoid host self-restriction. Our study characterized the unexpected phenotype of Escherichia coli cells, which manifested as extensive cell filamentation triggered by acquiring the Csp231I R–M system from Citrobacter sp. Surprisingly, we found that the cell morphology defect was solely dependent on the C regulator. Our transcriptome analysis supported by in vivo and in vitro assays showed that C protein directly silenced the expression of the RacR repressor to affect the Rac prophage-related genes. The rac locus ydaST genes, when derepressed, exerted a toxicity indicated by cell filamentation through an unknown mechanism. These results provide an apparent example of transcription factor cross-talk, which can have significant consequences for the host, and may represent a constraint on lateral gene transfer.

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Can Fibroblasts Be Reprogrammed into Macrophages?.

Blood ◽

10.1182/blood.v108.11.443.443 ◽

2006 ◽

Vol 108 (11) ◽

pp. 443-443

Author(s):

Ru Feng ◽

Thomas Graf

Keyword(s):

Transcription Factor ◽

Transcription Factors ◽

Cell Lines ◽

Fibroblast Cell ◽

Bzip Transcription Factor ◽

Nih3t3 Cells ◽

Activation Domains ◽

Gm Csf ◽

Infected Cells ◽

Factor C

Abstract Previous work showed that B cell precursors can be reprogrammed into functional macrophages by the enforced expression of the bZip transcription factor C/EBPalpha. The efficient activation of myelomonocytic genes, such as Mac-1, required the co-operation with endogenous PU.1 (Xie et al. 2004), reflecting the fact that many myelomonocytic genes are regulated by a combination of the two transcription factors. We therefore asked: Is C/EBPa and PU.1 sufficient to convert non-hematopoietic cells into macrophages? To test this, NIH-3T3 cells were co-infected with PU.1-GFP and C/EBPa-hCD4 retrovirusesor control vectors encoding the indicators GFP and hCD4 only. Uninfected cells in the retrovirus treated cultures served as additional controls. Our results showed that ~25% of the PU.1 only infected cells express Mac-1 and that this percentage could be increased ~3 fold by co-expression with C/EBPa. In addition, most cells also expressed CD45 and some expressed F4/80 antigen. The PU.1 infected and the double infected cells, but not the C/EBPa only infected cells, also expressed a number of other myelomonocytic genes as detected by RT-PCR. These included CSF-1R (M-CSFR), GM-CSF Ralpha, Lysozyme, CD32, PYK2 as well as endogenous PU.1. The PU.1 induced reprogramming of fibroblasts required the DNA binding and transcription activation domains, but not the PEST domain of the transcription factor. To test whether the reprogrammed cells have functional macrophage properties, we generated two stable cell lines co-expressing C/EBPa and PU.1 delta PEST (wild type PU.1 is toxic in long-term cultures). These cells were morphologically altered, ingested carboxylated particles, and expressed functional Fc-gamma receptors but were unable to phagocytize antibody coated red blood cells. Remarkably, the two cells lines acquired CSF-1 dependence for growth. In accordance with this finding they exhibited a 10–15 fold reduction of CSF-1 production compared to NIH3T3 cells. The response observed was not restricted to fibroblast cell lines since both embryonic and adult fibroblasts could also be partially reprogrammed by co-infection with PU.1 and C/EBPa in that they expressed Mac-1, CD45, F4/80 and IA MHC antigens. In conclusion, enforced expression of PU.1 and C/EBPa converts fibroblasts into macrophage like cells, indicating that the combination of these two transcription factors is sufficient to regulate the majority of genes that define the myelomonocytic phenotype.

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C-MYB and C/EBP Family Transcription Factors Regulate the Gfi-1 Promoter.

Blood ◽

10.1182/blood.v108.11.4214.4214 ◽

2006 ◽

Vol 108 (11) ◽

pp. 4214-4214

Author(s):

Richard Dahl ◽

Kristin S. Owens

Keyword(s):

Transcription Factor ◽

Transcription Factors ◽

Chromatin Immunoprecipitation ◽

Binding Sites ◽

Myeloid Cells ◽

Transient Transfection ◽

Mobility Shift ◽

Reporter Assays ◽

Immature Myeloid Cells ◽

Factor C

Abstract Gfi-1 −/− mice generate abnormal immature myeloid cells exhibiting characteristics of both monocytes and granulocytes. One of Gfi-1’s critical functions is to downregulate monocyte specific genes in order for granulocytes to develop properly. Since the transcription factors C/EBP alpha and C/EBP epsilon are needed for granulocyte development we hypothesized that these factors may regulate Gfi-1 expression. The Gfi-1 promoter contains several putative C/EBP binding sites and we show by electrophoretic mobility shift and chromatin immunoprecipitation that C/EBP family members can bind to some of these sites. However we were unable to see activation of the Gfi-1 promoter by C/EBP proteins in transient transfection reporter assays. Other groups have shown that C/EBP proteins can synergize with the transcription factor c-myb. We observed that the Gfi-1 promoter contains sites for the hematopoietic transcription factor c-myb. Sevral of these c-myb binding sites are adjacent to C/EBP binding sites. In reporter assays in non-hematopoietic cells c-myb activated the Gfi-1 promoter by itself and this activity was enhanced when we included either C/EBP alpha or epsilon in the transfection. Our data suggests that C/EBP proteins and c-myb regulate the transcription of Gfi-1 in myeloid cells.

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The transcription factor activity gradient (TAG) model: contemplating a contact-independent mechanism for enhancer–promoter communication

Genes & Development ◽

10.1101/gad.349160.121 ◽

2021 ◽

Author(s):

Jonathan P. Karr ◽

John J. Ferrie ◽

Robert Tjian ◽

Xavier Darzacq

Keyword(s):

Transcription Factor ◽

Transcription Factors ◽

Regulatory Elements ◽

Transcription Factor Activity ◽

Factor Activity ◽

New Model ◽

Unresolved Question ◽

Regulatory Information ◽

Independent Mechanism ◽

Coactivator P300

How distal cis-regulatory elements (e.g., enhancers) communicate with promoters remains an unresolved question of fundamental importance. Although transcription factors and cofactors are known to mediate this communication, the mechanism by which diffusible molecules relay regulatory information from one position to another along the chromosome is a biophysical puzzle—one that needs to be revisited in light of recent data that cannot easily fit into previous solutions. Here we propose a new model that diverges from the textbook enhancer–promoter looping paradigm and offer a synthesis of the literature to make a case for its plausibility, focusing on the coactivator p300.

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LSD1 defines erythroleukemia metabolism by controlling the lineage-specific transcription factors GATA1 and C/EBPα

Blood Advances ◽

10.1182/bloodadvances.2020003521 ◽

2021 ◽

Vol 5 (9) ◽

pp. 2305-2318

Author(s):

Kensaku Kohrogi ◽

Shinjiro Hino ◽

Akihisa Sakamoto ◽

Kotaro Anan ◽

Ryuta Takase ◽

...

Keyword(s):

Transcription Factor ◽

Transcription Factors ◽

Target Genes ◽

Aerobic Glycolysis ◽

Clinical Samples ◽

Gene Encoding ◽

Heme Synthesis ◽

Metabolic Remodeling ◽

Chromatin Immunoprecipitation Sequencing ◽

Factor C

Abstract Acute myeloid leukemia (AML) is a heterogenous malignancy characterized by distinct lineage subtypes and various genetic/epigenetic alterations. As with other neoplasms, AML cells have well-known aerobic glycolysis, but metabolic variations depending on cellular lineages also exist. Lysine-specific demethylase-1 (LSD1) has been reported to be crucial for human leukemogenesis, which is currently one of the emerging therapeutic targets. However, metabolic roles of LSD1 and lineage-dependent factors remain to be elucidated in AML cells. Here, we show that LSD1 directs a hematopoietic lineage-specific metabolic program in AML subtypes. Erythroid leukemia (EL) cells particularly showed activated glycolysis and high expression of LSD1 in both AML cell lines and clinical samples. Transcriptome, chromatin immunoprecipitation–sequencing, and metabolomic analyses revealed that LSD1 was essential not only for glycolysis but also for heme synthesis, the most characteristic metabolic pathway of erythroid origin. Notably, LSD1 stabilized the erythroid transcription factor GATA1, which directly enhanced the expression of glycolysis and heme synthesis genes. In contrast, LSD1 epigenetically downregulated the granulo-monocytic transcription factor C/EBPα. Thus, the use of LSD1 knockdown or chemical inhibitor dominated C/EBPα instead of GATA1 in EL cells, resulting in metabolic shifts and growth arrest. Furthermore, GATA1 suppressed the gene encoding C/EBPα that then acted as a repressor of GATA1 target genes. Collectively, we conclude that LSD1 shapes metabolic phenotypes in EL cells by balancing these lineage-specific transcription factors and that LSD1 inhibitors pharmacologically cause lineage-dependent metabolic remodeling.

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LncRNA lncLy6C induced by microbiota metabolite butyrate promotes differentiation of Ly6Chigh to Ly6Cint/neg macrophages through lncLy6C/C/EBPβ/Nr4A1 axis

Cell Discovery ◽

10.1038/s41421-020-00211-8 ◽

2020 ◽

Vol 6 (1) ◽

Author(s):

Yunhuan Gao ◽

Jiang Zhou ◽

Houbao Qi ◽

Jianmei Wei ◽

Yazheng Yang ◽

...

Keyword(s):

Transcription Factor ◽

Transcription Factors ◽

Gut Microbiota ◽

Promoter Region ◽

Inflammatory Monocytes ◽

Pathological Conditions ◽

Lysine Methyltransferases ◽

Factor C ◽

Two Populations ◽

Deficient Mice

AbstractMacrophages are mainly divided into two populations, which play a different role in physiological and pathological conditions. The differentiation of these cells may be regulated by transcription factors. However, it is unclear how to modulate these transcription factors to affect differentiation of these cells. Here, we found that lncLy6C, a novel ultraconserved lncRNA, promotes differentiation of Ly6Chigh inflammatory monocytes into Ly6Clow/neg resident macrophages. We demonstrate that gut microbiota metabolites butyrate upregulates the expression of lncLy6C. LncLy6C deficient mice had markedly increased Ly6Chigh pro-inflammatory monocytes and reduced Ly6Cneg resident macrophages. LncLy6C not only bound with transcription factor C/EBPβ but also bound with multiple lysine methyltransferases of H3K4me3 to specifically promote the enrichment of C/EBPβ and H3K4me3 marks on the promoter region of Nr4A1, which can promote Ly6Chigh into Ly6Cneg macrophages. As a result, lncLy6C causes the upregulation of Nr4A1 to promote Ly6Chigh inflammatory monocytes to differentiate into Ly6Cint/neg resident macrophages.

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