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The nucleosome remodeling and histone deacetylase (NuRD) complex physically associates with BCL11B to regulate murine T‐cell development. However, the function of NuRD complex in mature T cells remains unclear. Here, we characterize the fate and metabolism of human T cells in which key subunits of the NuRD complex or BCL11B are ablated. BCL11B and the NuRD complex bind to each other and repress natural killer (NK)‐cell fate in T cells. In addition, T cells upregulate the NK cell‐associated receptors and transcription factors, lyse NK‐cell targets, and are reprogrammed into NK‐like cells (ITNKs) upon deletion of MTA2, MBD2, CHD4, or BCL11B. ITNKs increase OPA1 expression and exhibit characteristically elongated mitochondria with augmented oxidative phosphorylation (OXPHOS) activity. OPA1‐mediated elevated OXPHOS enhances cellular acetyl‐CoA levels, thereby promoting the reprogramming efficiency and antitumor effects of ITNKs via regulating H3K27 acetylation at specific targets. In conclusion, our findings demonstrate that the NuRD complex and BCL11B cooperatively maintain T‐cell fate directly by repressing NK cell‐associated transcription and indirectly through a metabolic‐epigenetic axis, providing strategies to improve the reprogramming efficiency and antitumor effects of ITNKs. Synopsis: While BCL11b is known to bind the NuRD complex and be required for T cell development, the function of these factors in mature T cells has so far been unclear. This work demonstrates how the NuRD complex and BCL11B together maintain T‐cells from reprogramming into NK cells. T cells are reprogrammed into NK‐like cells upon deletion of MTA2, MBD2, or CHD4.BCL11B associates with the NuRD complex to repress OPA1 expression in T cells.OPA1‐mediated mitochondrial fusion facilitates ITNK reprogramming and cytotoxicity by increasing OXPHOS.Acetyl‐CoA elevated by OXPHOS promotes NK‐cell‐associated genes expression and antitumor effects in ITNKs by regulating H3K27 acetylation. [ABSTRACT FROM AUTHOR]

The bZip transcription factor MafB is expressed specifically in the myeloid lineage of the hematopoietic system and is up-regulated successively during myeloid differentiation from multipotent progenitors to macrophages. Here we report that this induction reflects an essential role of MafB in early myeloid and monocytic differentiation. We observed that the expression of MafB in transformed chicken hematopoietic precursors dramatically increases the proportion of myeloid colony formation at the expense of multipotent progenitor-type colonies. In addition, the overexpression of MafB in transformed myeloblasts stimulates the rapid formation of macrophages, as judged by morphology, surface marker expression and functional criteria. MafB-induced macrophages exhibit typical levels of phagocytic activity and nitric oxide release after activation by lipopolysaccharide. By contrast, overexpression of the myeloid transcription factor PU.1 in these cells does not induce macrophage differentiation. Furthermore, a dominant-negative allele of MafB inhibits both myeloid colony formation and the differentiation of myeloblasts into macrophages. Taken together, our results indicate that MafB induction is a specific and essential determinant of the monocytic program in hematopoietic cells. [ABSTRACT FROM AUTHOR]

The transcription factors Ets-1 and AML1 (the αBl subunit of PEBP2/CBF) play critical roles in hematopoiesis and leukemogenesis, and cooperate in the trans-activation of the T cell receptor (TCR) β chain enhancer. The DNA binding capacity of both factors is blocked intramolecularly but can be activated by the removal of negative regulatory domains. These include the exon VII domain for Ets-1 and the negative regulatory domain for DNA binding (NRDB) for αB1. Here we report that the direct interaction between the two factors leads to a reciprocal stimulation of their DNA binding activity and activation of their transactivation function. Detailed mapping revealed two independent contact points involving the exon VII and NRDB regions as well as the two DNA binding domains. Using deletion variants and dominant interfering mutants, we demonstrate that the interaction between exon VII and NRDB is necessary and sufficient for cooperative DNA binding. The exon VII and NRDB motifs are highly conserved in evolution yet deleted in natural variants, suggesting that the mechanism described is of biological relevance. The mutual activation of DNA binding of Ets and AML1 through the intermolecular interaction of autoinhibitory domains may represent a novel principle for the regulation of transcription factor function. [ABSTRACT FROM AUTHOR]

The EOS47 antigen is an early and specific marker of eosinophil differentiation in the chicken haematopoietic system. To elucidate the transciptional events controlling commitment to the eosinophil lineage, we studied the regulation of the eosinophil­specific EOS47 promoter. This promoter is TATA-less, and binds trancription factors of the Ets, C/EBP, GATA and Myb families. These sites are contained within a 309 bp promoter fragment which is sufficient for specific high level transcription in an eosinophil cell line. Co-transfection experiments in Q2bn fibroblasts showed cooperative activation of the EOS47 proximal promoter by c-Myb, Ets-1/Fli-1, GATA-1 and C/EBPα. The Ets-1/Fli-1 and C/EBPα proteins were the most potent activators, and acted with high synergy through juxtaposed binding sites located ∼60 bp upstream of the transcription start site. The Ets-1 and C/EBP proteins were found to associate physically via their DNA-binding domains and to bind their combined binding site cooperatively. GATA-1 showed biphasic regulation of the EOS47 promoter, activating at low and repressing at high protein concentrations. These results demonstrate combinatorial activation of an eosinophil-specific promoter by ubiquitous and lineage-restricted haematopoietic transcription factors. They also indicate that direct interactions between C/EBPs and specific Ets family members, together with GATA-1, are important for eosinophil lineage determination. [ABSTRACT FROM AUTHOR]

The distal enhancer region of the human immunodeficiency virus 1 (HIV-1) long terminal repeat (LTR) is known to be essential for HIV replication and to contain immediately adjacent E-box and Ets binding sites. Based on a yeast one-hybrid screen we have identified the E-box binding protein USF-1 as a direct interaction partner of Ets-1 and found that the complex acts on this enhancer element. The binding surfaces of USF-1 and Ets-1 map to their DNA-binding domains and although these domains are highly conserved, the interaction is very selective within the respective protein family. USF-1 and Ets-1 synergize in specific DNA binding as well as in the transactivation of reporter constructs containing the enhancer element, and mutations of the individual binding sites dramatically reduce reporter activity in T cells. In addition, a dominant negative Ets-1 mutant inhibits both USF-1-mediated transactivation and the activity of the HIV-1 LTR in T cells. The inhibition is independent of Ets DNA-binding sites but requires the Ets binding surface on USF-1, highlighting the importance of the direct protein­protein interaction. Together these results indicate that the interaction between Ets-1 and USF-1 is required for full transcriptional activity of the HIV-1 LTR in T cells. [ABSTRACT FROM AUTHOR]