Arginine methylation of the p30 C/EBPα oncoprotein regulates progenitor proliferation and myeloid differentiation.

The transcription factor CCAAT enhancer binding protein alpha (C/EBPα) is a master regulator of myelopoiesis. encodes a long (p42) and a truncated (p30) protein isoform from a single mRNA. Mutations that abnormally enhance expression of p30 are associated with acute myelogenous leukemia (AML).

C/EBPβ-induced lymphoid-to-myeloid transdifferentiation emulates granulocyte-monocyte progenitor biology.

CCAAT/enhancer-binding protein beta (C/EBPβ) induces primary v-Abl immortalized mouse B cells to transdifferentiate (BT, B cell transdifferentiation) into granulocyte-macrophage progenitor-like cells (GMPBTs). GMPBTs maintain cytokine-independent self-renewal, lineage choice, and multilineage differentiation. Single-cell transcriptomics demonstrated that GMPBTs comprise a continuum of myelomonopoietic differentiation states that seamlessly fit into state-to-fate maps of normal granulocyte-macrophage progenitors (GMPs).

Carm1-arginine methylation of the transcription factor C/EBPα regulates transdifferentiation velocity.

Here, we describe how the speed of C/EBPα-induced B cell to macrophage transdifferentiation (BMT) can be regulated, using both mouse and human models. The identification of a mutant of C/EBPα (C/EBPα) that greatly accelerates BMT helped to illuminate the mechanism. Thus, incoming C/EBPα binds to PU.

Immune cell C/EBPβ deficiency is associated with hepatic mononuclear defects and spontaneous hepatitis but not steatohepatitis induced liver fibrosis.

Background: CCAAT/enhancer-binding protein β (C/EBPβ) is a transcription factor known to be involved in macrophage differentiation and function, steatohepatitis and liver fibrosis.

Methods: Immune restricted C/EBPβ deficient and control mice were investigated in steady-state and in the CDA-HFD steatohepatitis model. Mice were assessed for weight change, liver biochemical profile, histology and hepatic phagocytes composition.

C/EBPβ regulates lipid metabolism and isoform 2 expression in alveolar macrophages.

Pulmonary alveolar proteinosis (PAP) is a syndrome characterized by accumulation of surfactant lipoproteins within the lung alveoli. Alveolar macrophages (AMs) are crucial for surfactant clearance, and their differentiation depends on colony-stimulating factor 2 (CSF2), which regulates the establishment of an AM-characteristic gene regulatory network. Here, we report that the transcription factor CCAAT/enhancer binding protein β (C/EBPβ) is essential for the development of the AM identity, as demonstrated by transcriptome and chromatin accessibility analysis.

Tongue immune compartment analysis reveals spatial macrophage heterogeneity.

The tongue is a unique muscular organ situated in the oral cavity where it is involved in taste sensation, mastication, and articulation. As a barrier organ, which is constantly exposed to environmental pathogens, the tongue is expected to host an immune cell network ensuring local immune defence. However, the composition and the transcriptional landscape of the tongue immune system are currently not completely defined.

CSF2-dependent monocyte education in the pathogenesis of ANCA-induced glomerulonephritis.

Objectives: Myeloid cell activation by antineutrophil cytoplasmic antibody (ANCA) is pivotal for necrotising vasculitis, including necrotising crescentic glomerulonephritis (NCGN). In contrast to neutrophils, the contribution of classical monocyte (CM) and non-classical monocyte (NCM) remains poorly defined. We tested the hypothesis that CMs contribute to antineutrophil cytoplasmic antibody-associated vasculitis (AAV) and that colony-stimulating factor-2 (CSF2, granulocyte-macrophage colony-stimulating factor (GM-CSF)) is an important monocyte-directed disease modifier.

A Universal Peptide Matrix Interactomics Approach to Disclose Motif-Dependent Protein Binding.

Protein-protein interactions mediated by intrinsically disordered regions are often based on short linear motifs (SLiMs). SLiMs are implicated in signal transduction and gene regulation yet remain technically laborious and notoriously challenging to study. Here, we present an optimized method for a protein interaction screen on a peptide matrix (PRISMA) in combination with quantitative MS.

PRISMA and BioID disclose a motifs-based interactome of the intrinsically disordered transcription factor C/EBPα.

C/EBPα represents a paradigm intrinsically disordered transcription factor containing short linear motifs and post-translational modifications (PTM). Unraveling C/EBPα protein interaction networks is a prerequisite for understanding the multi-modal functions of C/EBPα in hematopoiesis and leukemia. Here, we combined arrayed peptide matrix screening (PRISMA) with BioID to generate an validated and isoform specific interaction map of C/EBPα.

Myeloid transformation by - depends strictly on C/EBP.

Chromosomal rearrangements of the mixed-lineage leukemia gene are the hallmark of infant acute leukemia. The granulocyte-macrophage progenitor state forms the epigenetic basis for myelomonocytic leukemia stemness and transformation by MLL-type oncoproteins. Previously, it was shown that the establishment of murine myelomonocytic - transformation, but not its maintenance, depends on the transcription factor C/EBPα, suggesting an epigenetic hit-and-run mechanism of MLL-driven oncogenesis.

The transcription factor C/EBPβ orchestrates dendritic cell maturation and functionality under homeostatic and malignant conditions.

Dendritic cell (DC) maturation is a prerequisite for the induction of adaptive immune responses against pathogens and cancer. Transcription factor (TF) networks control differential aspects of early DC progenitor versus late-stage DC cell fate decisions. Here, we identified the TF C/EBPβ as a key regulator for DC maturation and immunogenic functionality under homeostatic and lymphoma-transformed conditions.

Publisher Correction: Cxcl10 monocytes define a pathogenic subset in the central nervous system during autoimmune neuroinflammation.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Author Correction: Cxcl10 monocytes define a pathogenic subset in the central nervous system during autoimmune neuroinflammation.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Cxcl10 monocytes define a pathogenic subset in the central nervous system during autoimmune neuroinflammation.

Multiple sclerosis (MS) is characterized by pathological inflammation that results from the recruitment of lymphoid and myeloid immune cells from the blood into the brain. Due to subset heterogeneity, defining the functional roles of the various cell subsets in acute and chronic stages of MS has been challenging. Here, we used index and transcriptional single-cell sorting to characterize the mononuclear phagocytes that infiltrate the central nervous system from the periphery in mice with experimentally induced autoimmune encephalomyelitis, a model of MS.

C/EBPβ-Dependent Epigenetic Memory Induces Trained Immunity in Hematopoietic Stem Cells.

Hematopoietic stem cells (HSCs) maintain life-long production of immune cells and can directly respond to infection, but sustained effects on the immune response remain unclear. We show that acute immune stimulation with lipopolysaccharide (LPS) induced only transient changes in HSC abundance, composition, progeny, and gene expression, but persistent alterations in accessibility of specific myeloid lineage enhancers occurred, which increased responsiveness of associated immune genes to secondary stimulation. Functionally, this was associated with increased myelopoiesis of pre-exposed HSCs and improved innate immunity against the gram-negative bacterium P.

PRISMA: Protein Interaction Screen on Peptide Matrix Reveals Interaction Footprints and Modifications- Dependent Interactome of Intrinsically Disordered C/EBPβ.

CCAAT enhancer-binding protein beta (C/EBPβ) is a pioneer transcription factor that specifies cell differentiation. C/EBPβ is intrinsically unstructured, a molecular feature common to many proteins involved in signal processing and epigenetics. The structure of C/EBPβ differs depending on alternative translation initiation and multiple post-translational modifications (PTM).

A C/EBPα-Wnt connection in gut homeostasis and carcinogenesis.

We explored the connection between C/EBPα (CCAAT/enhancer-binding protein α) and Wnt signaling in gut homeostasis and carcinogenesis. C/EBPα was expressed in human and murine intestinal epithelia in the transit-amplifying region of the crypts and was absent in intestinal stem cells and Paneth cells with activated Wnt signaling. In human colorectal cancer and murine APC polyps, C/EBPα was absent in the nuclear β-catenin-positive tumor cells.

The C/EBPβ LIP isoform rescues loss of C/EBPβ function in the mouse.

The transcription factor C/EBPβ regulates hematopoiesis, bone, liver, fat, and skin homeostasis, and female reproduction. C/EBPβ protein expression from its single transcript occurs by alternative in-frame translation initiation at consecutive start sites to generate three isoforms, two long (LAP*, LAP) and one truncated (LIP), with the same C-terminal bZip dimerization domain. The long C/EBPβ isoforms are considered gene activators, whereas the LIP isoform reportedly acts as a dominant-negative repressor.

Loss-of-function uORF mutations in human malignancies.

Ribosome profiling revealed widespread translational activity at upstream open reading frames (uORFs) and validated uORF-mediated translational control as a commonly repressive mechanism of gene expression. Translational activation of proto-oncogenes through loss-of-uORF mutations has been demonstrated, yet a systematic search for cancer-associated genetic alterations in uORFs is lacking. Here, we applied a PCR-based, multiplex identifier-tagged deep sequencing approach to screen 404 uORF translation initiation sites of 83 human tyrosine kinases and 49 other proto-oncogenes in 308 human malignancies.

SIRT1 regulates macrophage self-renewal.

Mature differentiated macrophages can self-maintain by local proliferation in tissues and can be extensively expanded in culture under specific conditions, but the mechanisms of this phenomenon remain only partially defined. Here, we show that SIRT1, an evolutionary conserved regulator of life span, positively affects macrophage self-renewal ability and Overexpression of SIRT1 during bone marrow-derived macrophage differentiation increased their proliferative capacity. Conversely, decrease of SIRT1 expression by shRNA inactivation, CRISPR/Cas9 mediated deletion and pharmacological inhibition restricted macrophage self-renewal in culture.

Genomic Characterization of Murine Monocytes Reveals C/EBPβ Transcription Factor Dependence of Ly6C Cells.

Monocytes are circulating, short-lived mononuclear phagocytes, which in mice and man comprise two main subpopulations. Murine Ly6C monocytes display developmental plasticity and are recruited to complement tissue-resident macrophages and dendritic cells on demand. Murine vascular Ly6C monocytes patrol the endothelium, act as scavengers, and support vessel wall repair.

C/EBP-Induced Transdifferentiation Reveals Granulocyte-Macrophage Precursor-like Plasticity of B Cells.

The lymphoid-myeloid transdifferentiation potentials of members of the C/EBP family (C/EBPα, β, δ, and ε) were compared in v-Abl-immortalized primary B cells. Conversion of B cells to macrophages was readily induced by the ectopic expression of any C/EBP, and enhanced by endogenous C/EBPα and β activation. High transgene expression of C/EBPβ or C/EBPε, but not of C/EBPα or C/EBPδ, also induced the formation of granulocytes.