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The first formal description of the microbicidal activity of extracellular traps (ETs) containing DNA occurred in neutrophils in 2004. Since then, ETs have been identified in different populations of cells involved in both innate and adaptive immune responses. Much of the knowledge has been obtained from in vitro or ex vivo studies; however, in vivo evaluations in experimental models and human biological materials have corroborated some of the results obtained. Two types of ETs have been described—suicidal and vital ETs, with or without the death of the producer cell. The studies showed that the same cell type may have more than one ETs formation mechanism and that different cells may have similar ETs formation mechanisms. ETs can act by controlling or promoting the mechanisms involved in the development and evolution of various infectious and non-infectious diseases, such as autoimmune, cardiovascular, thrombotic, and neoplastic diseases, among others. This review discusses the presence of ETs in neutrophils, macrophages, mast cells, eosinophils, basophils, plasmacytoid dendritic cells, and recent evidence of the presence of ETs in B lymphocytes, CD4+ T lymphocytes, and CD8+ T lymphocytes. Moreover, due to recently collected information, the effect of ETs on COVID-19 is also discussed.

Somatic mutations affecting ETV6 often occur in acute lymphoblastic leukemia (ALL), the most common childhood malignancy. The genetic factors that predispose to ALL remain poorly understood. Here we identify a novel germline ETV6 p. L349P mutation in a kindred affected by thrombocytopenia and ALL. A second ETV6 p. N385fs mutation was identified in an unrelated kindred characterized by thrombocytopenia, ALL and secondary myelodysplasia/acute myeloid leukemia. Leukemic cells from the proband in the second kindred showed deletion of wild type ETV6 with retention of the ETV6 p. N385fs. Enforced expression of the ETV6 mutants revealed normal transcript and protein levels, but impaired nuclear localization. Accordingly, these mutants exhibited significantly reduced ability to regulate the transcription of ETV6 target genes. Our findings highlight a novel role for ETV6 in leukemia predisposition.

Cutaneous melanoma occurs in both familial and sporadic forms. We investigated a melanoma-prone family through linkage analysis and high-throughput sequencing and identified a disease-segregating germline mutation in the promoter of the telomerase reverse transcriptase (TERT) gene, which encodes the catalytic subunit of telomerase. The mutation creates a new binding motif for Ets transcription factors and ternary complex factors (TCFs) near the transcription start and, in reporter gene assays, caused up to twofold increase in transcription. We then screened the TERT promoter in sporadic melanoma and observed recurrent ultraviolet signature somatic mutations in 125 of 168 (74%) of human cell lines derived from metastatic melanomas, 45 of 53 corresponding metastatic tumor tissues (85%), and 25 of 77 (33%) primary melanomas. The majority of those mutations occurred at two positions in the TERT promoter and also generated binding motifs for Ets/TCF transcription factors.

In inflamed tissues, monocytes differentiate into macrophages (mo-Macs) or dendritic cells (mo-DCs). In chronic nonresolving inflammation, mo-DCs are major drivers of pathogenic events. Manipulating monocyte differentiation would therefore be an attractive therapeutic strategy. However, how the balance of mo-DC versus mo-Mac fate commitment is regulated is not clear. In the present study, we show that the transcriptional repressors ETV3 and ETV6 control human monocyte differentiation into mo-DCs. ETV3 and ETV6 inhibit interferon (IFN)-stimulated genes; however, their action on monocyte differentiation is independent of IFN signaling. Instead, we find that ETV3 and ETV6 directly repress mo-Mac development by controlling MAFB expression. Mice deficient for Etv6 in monocytes have spontaneous expression of IFN-stimulated genes, confirming that Etv6 regulates IFN responses in vivo. Furthermore, these mice have impaired mo-DC differentiation during inflammation and reduced pathology in an experimental autoimmune encephalomyelitis model. These findings provide information about the molecular control of monocyte fate decision and identify ETV6 as a therapeutic target to redirect monocyte differentiation in inflammatory disorders. The factors controlling monocyte fate commitment toward macrophages versus dendritic cells are unclear. Here the authors show that ETV3 and ETV6 enable dendritic cell differentiation by repressing the macrophage transcriptional program.

One function of Mediator complex subunit MED23 is to mediate transcriptional activation by the phosphorylated transcription factor Elk-1, in response to the Ras-MAPK signaling pathway. Using cryogenic electron microscopy, we solve a 3.0 Å structure of human MED23 complexed with the phosphorylated activation domain of Elk-1. Elk-1 binds to MED23 via a hydrophobic sequence PSIHFWSTLS P P containing one phosphorylated residue (S383 p ), which forms a tight turn around the central Phenylalanine. Binding of Elk-1 induces allosteric changes in MED23 that propagate to the opposite face of the subunit, resulting in the dynamic behavior of a 19-residue segment, which alters the molecular surface of MED23. We design a specific MED23 mutation (G382F) that disrupts Elk­-1 binding and consequently impairs Elk-1-dependent serum-induced activation of target genes in the Ras-Raf-MEK-ERK signaling pathway. The structure provides molecular details and insights into a Mediator subunit-transcription factor interface. The Mediator complex subunit MED23 contributes to transcriptional activation by the phosphorylated transcription factor Elk-1, in response to Ras-MAPK signalling. Here, the authors determine a cryo-EM structure of human MED23 with the phosphorylated activation domain of Elk-1 providing insights into the Mediator subunit-transcription factor interface.

Glucose metabolic reprogramming is a key hallmark of tumour cells, and the designed inhibitors targeting tumour glucose metabolism reprogramming may serve as an effective therapeutic strategy. The ETS Variant Transcription Factor 6 (ETV6) is a potent transcriptional repressor strongly associated with tumorgenesis. However, the precise role and underlying action mechanism of ETV6 in tumour glucose metabolism reprogramming remain unreported. In this study, we demonstrate that the ETV6‐miR‐429‐CRKL regulatory axis contributes to metabolism reprogramming in HCC. Overexpression or knockdown of ETV6 and CRKL enhances or inhibits the Warburg effect and glycogen synthesis in HCC cells both in vitro and in vivo. In contrast, miR‐429 overexpression and knockdown exert opposing effects on the Warburg effect compared to the overexpression and knockdown of ETV6 and CRKL. Moreover, miR‐429 regulates the rate of glycogen production and degradation by enhancing the activities of GCS and GPa to promote glycogen synthesis, subsequently coupling with the aerobic glycolytic pathway by mediating glycogen shunting. Mechanistically, ETV6 binds to the miR‐429 promoter, mediating glucose metabolic reprogramming in HCC cells by targeting CRKL via the PI3K/AKT pathway. Taken together, these findings reveal that the ETV6‐miR‐429‐CRKL regulatory circuitry plays a crucial role in glucose metabolic reprogramming in HCC, offering novel insight and a potential target for cancer therapy.

Multisite phosphorylation regulates many transcription factors, including the serum response factor partner Elk-1. Phosphorylation of the transcriptional activation domain (TAD) of Elk-1 by the protein kinase ERK at multiple sites potentiates recruitment of the Mediator transcriptional coactivator complex and transcriptional activation, but the roles of individual phosphorylation events had remained unclear. Using time-resolved nuclear magnetic resonance spectroscopy, we found that ERK2 phosphorylation proceeds at markedly different rates at eight TAD sites in vitro, which we classified as fast, intermediate, and slow. Mutagenesis experiments showed that phosphorylation of fast and intermediate sites promoted Mediator interaction and transcriptional activation, whereas modification of slow sites counteracted both functions, thereby limiting Elk-1 output. Progressive Elk-1 phosphorylation thus ensures a self-limiting response to ERK activation, which occurs independently of antagonizing phosphatase activity.

Key Points ETS factor expression is aberrantly upregulated in solid tumours through chromosomal translocation and amplification. Activating mutations in KIT stabilize the ETV1 protein through the MEK–ERK pathway, thus driving an oncogenic transcriptional programme in gastrointestinal stromal tumours. Disruption of constitutive photomorphogenesis protein 1 (COP1)-mediated proteasomal degradation of ETS factors increases their protein stability and subsequent transcriptional activity in prostate and breast cancers. Mutations in the telomerase reverse transcriptase ( TERT ) promoter that generate an ETS-binding site are emerging as among the most frequent mutations in solid tumours. Gain of function cis -acting mutations in p53 (p53-GOF mutants) result in ETS2 protein–protein interactions and altered target gene expression affecting tumour growth, metastasis and chemotherapeutic resistance. ETS factors mediate lineage specification altering stem and progenitor populations in multiple cancer types. ETS fusion proteins interact with poly(ADP-ribose) polymerase 1 (PARP1) and DNA-dependent protein kinase catalytic subunit (DNA-PKcs), both of which are mediators of DNA repair and genomic stability. ETS2 functions with p53-GOF mutants to epigenetically regulate super-enhancers. ETS factors function in both cell-autonomous and non-cell-autonomous manners in the tumour microenvironment to enhance cancer progression. Therapeutic strategies targeting ETS factor biology are emerging and should translate clinically in the next decade. Initially identified more than 30 years ago, the ETS family of transcription factors has been found to take part in all steps of tumorigenesis. This Review discusses the different mechanisms of ETS activation and the oncogenic implications of this activation, as well as how to target ETS factors in cancer treatment. Findings over the past decade have identified aberrant activation of the ETS transcription factor family throughout all stages of tumorigenesis. Specifically in solid tumours, gene rearrangement and amplification, feed-forward growth factor signalling loops, formation of gain-of-function co-regulatory complexes and novel cis -acting mutations in ETS target gene promoters can result in increased ETS activity. In turn, pro-oncogenic ETS signalling enhances tumorigenesis through a broad mechanistic toolbox that includes lineage specification and self-renewal, DNA damage and genome instability, epigenetics and metabolism. This Review discusses these different mechanisms of ETS activation and subsequent oncogenic implications, as well as the clinical utility of ETS factors.

Dynamic changes in mechanical microenvironments, such as cell crowding, regulate lineage fates as well as cell proliferation. Although regulatory mechanisms for contact inhibition of proliferation have been extensively studied, it remains unclear how cell crowding induces lineage specification. Here we found that a well-known oncogene, ETS variant transcription factor 4 (ETV4), serves as a molecular transducer that links mechanical microenvironments and gene expression. In a growing epithelium of human embryonic stem cells, cell crowding dynamics is translated into ETV4 expression, serving as a pre-pattern for future lineage fates. A switch-like ETV4 inactivation by cell crowding derepresses the potential for neuroectoderm differentiation in human embryonic stem cell epithelia. Mechanistically, cell crowding inactivates the integrin–actomyosin pathway and blocks the endocytosis of fibroblast growth factor receptors (FGFRs). The disrupted FGFR endocytosis induces a marked decrease in ETV4 protein stability through ERK inactivation. Mathematical modelling demonstrates that the dynamics of cell density in a growing human embryonic stem cell epithelium precisely determines the spatiotemporal ETV4 expression pattern and, consequently, the timing and geometry of lineage development. Our findings suggest that cell crowding dynamics in a stem cell epithelium drives spatiotemporal lineage specification using ETV4 as a key mechanical transducer. Yang, Golkaram et al. reported that in human embryonic stem cells, cellular crowding leads to the blockade of FGFR1 endocytosis, resulting in a decrease in ETV4 expression. This, in turn, derepresses the neuroectoderm fate.

VEGFA signaling controls physiological and pathological angiogenesis and hematopoiesis. Although many context-dependent signaling pathways downstream of VEGFA have been uncovered, vegfa transcriptional regulation in vivo remains unclear. Here, we show that the ETS transcription factor, Etv6, positively regulates vegfa expression during Xenopus blood stem cell development through multiple transcriptional inputs. In agreement with its established repressive functions, Etv6 directly inhibits expression of the repressor foxo3 , to prevent Foxo3 from binding to and repressing the vegfa promoter. Etv6 also directly activates expression of the activator klf4 ; reflecting a genome-wide paucity in ETS-binding motifs in Etv6 genomic targets, Klf4 then recruits Etv6 to the vegfa promoter to activate its expression. These two mechanisms (double negative gate and feed-forward loop) are classic features of gene regulatory networks specifying cell fates. Thus, Etv6’s dual function, as a transcriptional repressor and activator, controls a major signaling pathway involved in endothelial and blood development in vivo. How vegfa expression is transcriptionally regulated in vivo is unclear. Here, the authors demonstrate that the ETS transcription factor Etv6 acts as a repressor and an activator of two direct regulators of vegfa expression ( foxo3 and klf4 , respectively) to control blood formation in Xenopus .