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At least 19 recordsLinked to original sources

Brachyury expression levels predict lineage potential and axis-forming ability of in vitro-derived neuromesodermal progenitors.

Neuromesodermal progenitors (NMPs) produce the spinal cord and musculoskeleton in the elongating anterior-posterior axis. In vivo, NMPs possess dual potency, coinciding with regions co-expressing SOX2 and Brachyury (TBXT). In vitro, SOX2/TBXT co-expressing cells can be produced from pluripotent cells and, like their in vivo counterparts, can produce neural tube and somitic mesoderm. However, the functional characteristics of in vitro SOX2/TBXT co-expressing cells remain unclear, confounding comparisons with in vivo data. To address this, we developed a dual Sox2/Tbxt reporter mouse ESC line. SOX2/TBXT reporter-positive cells emerge in vitro from pluripotent populations with dynamics that mirror their appearance in the embryo. Purified SOX2/TBXT co-expressing populations can differentiate towards neurectoderm or mesoderm, including lateral mesoderm upon BMP stimulation. In gastruloids, quantitative live imaging shows that WNT or NOTCH inhibition rapidly leads to downregulation of TBXT expression and diminished axial extension. We show that clonally plated SOX2/TBXT co-expressing cells are bipotent NMPs that can also self-propagate. By combining clonal analysis with mathematical inference, we identify two thresholds of TBXT and/or SOX2 expression, switching clonal output from neural- to mesoderm-biased, and from mesoderm-biased to mesoderm-specified. Image analysis of embryonic NMPs supports a model whereby SOX2 and TBXT independently influence neuromesodermal differentiation. Thus, this Sox2/Tbxt double reporter cell line highlights unsuspected heterogeneity in NMPs, and together with image analysis of embryonic SOX2/TBXT levels, challenges the assumption that neuromesodermal fate choice is primarily governed by mutual antagonism between SOX2/TBXT.

Animals↗

The evolution of vertebrate gastrulation.

The availability of molecular markers now permits the analysis of the common elements of vertebrate gastrulation. While gastrulation appears to be very diverse in the vertebrates, by analyzing a head-organizer marker, goosecoid, and a marker common to all forming mesoderm, Brachyury, we attempt to identify homologous structures and equivalent stages in Xenopus, zebrafish, chick and mouse gastrulation. Using a tail-organizer marker, Xnot-2, we also discuss how the late stages of gastrulation lead to the formation of the postanal tail, a structure characteristic of the chordates.

Animals↗

The T protein encoded by Brachyury is a tissue-specific transcription factor.

The mouse Brachyury (T) gene is required for differentiation of the notochord and formation of mesoderm during posterior development. Homozygous embryos lacking T activity do not develop a trunk and tail and die in utero. The T gene is specifically expressed in notochord and early mesoderm cells in the embryo. recent data have demonstrated that the T protein is localized in the cell nucleus and specifically binds to a palindrome of 20 bp (the T site) in vitro. We show that the T protein activates expression of a reporter gene in HeLa cells through binding to the T site. Thus T is a novel tissue-specific transcription factor. It consists of a large N-terminal DNA binding domain (amino acids 1-229) and two pairs of transactivation and repression domains in the C-terminal protein half. T can also transactivate transcription through variously oriented and spaced T sites, a fact that may be relevant in the search for genes controlled by T protein and important in mesoderm development.

Animals↗

Control of somitic expression of tenascin in Xenopus embryos by myogenic factors and Brachyury.

Tenascin is a large glycoprotein which is expressed in a restricted pattern in the extracellular matrix (ECM) of vertebrate embryos. Tenascin interferes with cell-fibronectin interactions in vitro, and may play a role in the control of cell migration and differentiation during development. In Xenopus, tenascin immunoreactivity is first detected at the early tailbud stage in the ECM of the most anterior somite. Thereafter, it is distributed dorsally along neural crest cell migration pathways. In this paper, we report that tenascin mRNA is most abundant in dorsal mesoderm at the neurula stage and in somites at the early tailbud stage, indicating that the initial accumulation of tenascin in the ECM is due to secretion from paraxial mesoderm. To understand how tenascin expression in somitic mesoderm is controlled, we have expressed Xbra and the myogenic factors XMyoD and XMyf5 in blastula animal cap tissue. The tenascin gene is activated by all three transcription factors. Interestingly, expression of tenascin mRNA, and accumulation of the protein in the ECM, can occur without formation of muscle. Our results suggest that tenascin regionalization in early Xenopus embryos depends on tenascin RNA expression by somitic mesoderm, where it is likely to be activated by myogenic factors.

Animals↗

Mesoderm induction in Xenopus caused by activation of MAP kinase.

Mesoderm induction is a critical early step in vertebrate development, involving changes in gene expression and morphogenesis. In Xenopus, normal mesoderm formation depends on signalling through the fibroblast growth factor (FGF) tyrosine kinase receptor. One important signalling pathway from receptor tyrosine kinases involves p21ras (ref. 5). Ras associates with the serine kinase c-Raf-1 in a GTP-dependent manner, and this complex phosphorylates and activates MAPK/ERK kinase (MEK), a protein kinase with dual specificity. MEK then activates p42mapk and (at least in mammals) p44mapk, members of the mitogen-activated protein (MAP) kinase family. FGF activates MAP kinase during mesoderm induction, and the use of dominant-negative constructs suggests that mesoderm induction by FGF requires both Ras and Raf. However, these experiments do not reveal whether Ras and Raf do act through MAP kinase to induce mesoderm or whether another pathway, such as the phosphatidylinositol 3-kinase cascade, is involved. Here we show that expression of active forms of MEK or of MAP kinase induces ventral mesoderm of the kind elicited by FGF. Overexpression of a Xenopus MAP kinase phosphatase blocks mesoderm induction by FGF, and causes characteristic defects in mesoderm formation in intact embryos, whereas inhibition of the P13 kinase and p70 S6 kinase pathways has no effect on mesoderm induction by FGF. FGF induces different types of mesoderm in a dose-dependent manner; strikingly, this is mimicked by expressing different levels of activated MEK. Together, these experiments demonstrate that activation of MAP kinases is necessary and sufficient for mesoderm formation.

Actins↗

A homology domain shared between Drosophila optomotor-blind and mouse Brachyury is involved in DNA binding.

The distribution of sequence elements divides the optomotor-blind protein into three regions and is suggestive of a transcriptional regulatory role of this protein. The central region of Omb is homologous to the N-terminal half of the Brachyury protein. The conserved domain of Omb is here shown to possess general DNA binding affinity but has no significant similarity to recognized DNA binding motifs.

Amino Acid Sequence↗

The molecular landscape of chordoma: Current frontiers from multi-omics to artificial intelligence.

Chordoma is a rare and aggressive malignant bone tumor of the axial skeleton that has historically challenged clinicians due to its complex anatomical locations and a high recurrence rate of up to 85%. This review synthesizes the most recent advances in chordoma research and offers an overview of how multi-omics, advanced immunology, and artificial intelligence are reshaping the treatment paradigm. Central to its pathogenesis is the T-box transcription factor Brachyury, which this review highlights as both the pathognomonic diagnostic marker and the primary therapeutic vulnerability. Cutting-edge innovations targeting this driver include covalent small-molecule binders, targeted protein degradation, and peptide-centric CAR-T cells designed to attack the intracellular oncoprotein. The tumor immune microenvironment is functionally dynamic, and new dimensions in cellular therapy, such as dual-specific CAR constructs and NK-cell platforms, are being engineered to neutralize immunosuppressive factors. Beyond biological insights, the review emphasizes the role of computational biology, specifically how deep-learning and machine-learning models achieve expert-level precision in tumor segmentation and personalized survival forecasting. By integrating genomic, transcriptomic, epigenomic, and proteomic data, multiomics approaches can fully elucidate chordoma subtypes and underlying resistance mechanisms, ultimately paving the way for more precise and personalized therapeutic strategies.

Humans↗

Epigenomic analysis of primary human T cells reveals enhancers associated with TH2 memory cell differentiation and asthma susceptibility.

A characteristic feature of asthma is the aberrant accumulation, differentiation or function of memory CD4(+) T cells that produce type 2 cytokines (TH2 cells). By mapping genome-wide histone modification profiles for subsets of T cells isolated from peripheral blood of healthy and asthmatic individuals, we identified enhancers with known and potential roles in the normal differentiation of human TH1 cells and TH2 cells. We discovered disease-specific enhancers in T cells that differ between healthy and asthmatic individuals. Enhancers that gained the histone H3 Lys4 dimethyl (H3K4me2) mark during TH2 cell development showed the highest enrichment for asthma-associated single nucleotide polymorphisms (SNPs), which supported a pathogenic role for TH2 cells in asthma. In silico analysis of cell-specific enhancers revealed transcription factors, microRNAs and genes potentially linked to human TH2 cell differentiation. Our results establish the feasibility and utility of enhancer profiling in well-defined populations of specialized cell types involved in disease pathogenesis.

Adolescent↗

Discrete endogenous signals mediate neural competence and induction in P19 embryonal carcinoma stem cells.

Endogenous signals capable of inducing neuroectodermal differentiation are expressed by differentiating P19 EC cells in vitro. The present study demonstrates that at least two discrete signals are required. One is expressed by isolated primitive streak mesoderm-like cell lines and has the capacity to induce the expression of Pax-3 but, alone, induces neural differentiation inefficiently. The second signal is not expressed by the primitive streak mesoderm-like cell line but is present in conditioned media from differentiating P19 EC cells following DMSO treatment. This signal does not induce either Pax-3 expression or morphological differentiation and does not commit stem cells to a neuroectodermal fate. Rather, it acts synergistically with the signal derived from the primitive streak mesoderm-like cells to increase the efficiency with which stem cells respond initially by Pax-3 expression and subsequently by differentiation towards neural lineages. The activity of this second signal can be replaced by forskolin and 3-isobutyl-1-methyl-xanthine suggesting that its effects are transduced by a cyclic nucleotide-dependent pathway.

1-Methyl-3-isobutylxanthine↗

rel, NFKB, and the Brachyury T gene.

Comparing the sequences of the murine Brachyury T gene protein with the NKFB, rel and dorsal protein family reveals weak sequence similarities, including a DNA-binding/dimerization motif. These similarities may reflect homologies between these proteins or may only be of phylogenetic relevance.

Amino Acid Sequence↗

The lethal(1)optomotor-blind gene of Drosophila melanogaster is a major organizer of optic lobe development: isolation and characterization of the gene.

The X-chromosomal complementation unit lethal(1)optomotor-blind [l(1)omb] is defined by lack of complementation among over a dozen recessive lethal mutations that map to the omb gene locus. Mutations in l(1)omb also fail to complement viable mutations of three seemingly unrelated functions in this region: bifid (bi), manifesting defective wings, Quadroon (Qd), a semi-dominant mutation expressing abnormal tergite pigmentation, and In(1)ombH31, giving rise to a normal external morphology but with discrete defects in the optic lobes and behavior. The locus encodes a 70-kilobase primary transcript that is spliced into a 6-kilobase mature RNA. cDNAs for this transcript were isolated and sequenced and the derived amino acid sequence was analyzed. Certain features of this sequence suggest that the l(1)omb gene product is a nuclear regulatory protein. The lethal phase of various apparent null mutants was determined and found to occur mainly in the pupal stage. A large proportion of all hemizygous mutant males develop to pharate adults that eclose only rarely but can be rescued from the pupal case. These animals show a severe maldevelopment of the optic lobes. In addition they have only rudimentary wings as well as a Quadroon-like abdominal pigmentation. Thus, in the lethal mutants those parts of the body are affected for which independent viable mutations have been previously described in the omb locus, such as optomotor-blind, bifid, and Quadroon.

Amino Acid Sequence↗

A sea urchin homologue of the chordate Brachyury (T) gene is expressed in the secondary mesenchyme founder cells.

Chordates are thought to have emerged from some common ancestor of deuterostomes by organizing shared anatomical and embryological features including a notochord, a dorsal nerve cord and pharyngeal gill slits. Because the notochord is the most prominent feature of chordates and because the Brachyury (T) gene is essential for notochord formation, the T gene is a key molecular probe with which to explore the origin and evolution of chordates. We investigated whether the sea urchin (echinoderm) conserves the T gene and, if so, where the sea urchin T gene is expressed. A cDNA clone for the sea urchin T (HpTa) gene contained a long open reading frame that encodes a polypeptide of 434 amino acids. Although the overall degree of amino acid identity was not very high (52%, sea urchin/mouse), in the T domain of the N terminus the amino acid identity was 73% (sea urchin/mouse). The HpTa gene is present as a single copy per haploid genome. As with the chordate T gene, the expression of HpTa is transient, being first detected in the swimming blastula, maximally transcribed in the gastrula, decreasing at the prism larval stage and barely detectable at the pluteus larval stage. HpTa transcripts were found in the secondary mesenchyme founder cells, vegetal plate of the mesenchyme blastula, extending tip of the invaginating archenteron and, finally, the secondary mesenchyme cells at the late-gastrula stage.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗

Mesoderm formation in response to Brachyury requires FGF signalling.

BACKGROUND: The Brachyury (T) gene is required for the formation of posterior mesoderm and for axial development in both mouse and zebrafish embryos. In these species, and in Xenopus, the gene is expressed transiently throughout the presumptive mesoderm, and transcripts then persiste in notochord and posterior tissues. In Xenopus embryos, expression of the Xenopus homologue of Brachyury, Xbra, can be induced in presumptive ectoderm by basic fibroblast growth factor (FGF) and activin; in the absence of functional FGF or activin signalling pathways, expression of the gene is severely reduced. Ectopic expression of Xbra in presumptive ectoderm causes mesoderm to be formed. As Brachyury and its homologues encode sequence-specific DNA-binding proteins, it is likely that each functions by directly activating downstream mesoderm-specific genes. RESULTS: We show that expression in Xenopus embryos of RNA encoding a dominant-negative FGF receptor inhibits the mesoderm-inducing activity of Xbra. We demonstrate that ectopic expression of Xbra activates transcription of the embryonic FGF gene, and that embryonic FGF can induce expression of Xbra. This suggests that the two genes are components of a regulatory loop. Consistent with this idea, dissociation of Xbra-expressing cells causes a dramatic and rapid reduction in levels of Xbra, but the reduction can be inhibited by addition of FGF. CONCLUSION: Formation of mesoderm tissue requires an intact FGF signalling pathway downstream of Brachyury. This requirement is due to a regulatory loop, in which Brachyury activates expression of a member of the FGF family, and FGF maintains expression of Brachyury.(ABSTRACT TRUNCATED AT 250 WORDS)

Activins↗

Analysis of FGF function in normal and no tail zebrafish embryos reveals separate mechanisms for formation of the trunk and the tail.

To analyse the roles of FGF activity and brachyury during gastrulation we have directly compared the consequences of inhibition of FGF-receptor signalling with the phenotype of the zebrafish brachyury mutant, no tail (ntl). We show that expression of ntl is regulated by FGF and that inhibition of FGF receptor-signalling leads to complete loss of the trunk and tail. Since the ntl mutant lacks the tail and notochord but has an otherwise normal trunk, this demonstrates that trunk development is dependent upon an unidentified gene, or set of genes, referred to as no trunk (ntk) which is regulated by FGF. We propose a model to explain the FGF-dependent regulation of ntl and ntk that accounts for the above phenotypes. Consistent with this model, over-expression of eFGF led to suppression of anterior fates and development of trunk and tail derivatives only. In addition, widespread activation of convergence and extension movements resulted in the formation of multiple axis-like structures. Expression of eve1 and cad1 was also regulated by FGF activity, suggesting that during gastrulation FGF activity is normally restricted to the germ ring where these genes, and ntl, are expressed. Taken together these data suggest that the germ ring acts as a posteriorising centre during AP patterning, mediated by FGF activity in this tissue.

Animals↗

Chasing tails in ascidians: developmental insights into the origin and evolution of chordates.

The ascidian tadpole larva is regarded as a prototype of the ancestral chordate. Here we consider recent studies on the development of the tadpole larva that provide new insights into chordate origins and evolution. The notochord of ascidian larvae and vertebrates appear to be homologous structures based on their induction by endoderm and expression of the Brachyury (T) gene. The muscle cells of ascidian larvae also appear homologous to those of vertebrates based on their expression of bHLH myogenic and muscle-type actin genes, although they are specified by cytoplasmic determinants localized in the egg as well as embryonic induction. Studies of the tailless larvae of anural ascidians have resulted in the identification of Manx, a gene that may control tail development and evolution. These and other results support the ascidian tadpole prototype for the ancestral chordate.

Actins↗

Is there a Brachyury the Second? Analysis of a transgenic mutation involved in notochord maintenance in mice.

A new phenotype mapping to the t-complex, which is designated Brachyury the Second (T2), is characterized by a slightly shortened tail in heterozygotes and homozygous failure to form an organized notochord with subsequent abnormal development of posterior somites and neural tube. The phenotype of T2 superficially resembles that of Brachyury; however, there are several important differences. Brachyury homozygotes fail to make posterior somites, notochord, floor plate, and a placental connection, resulting in death by 10.5 days of development. In contrast, T2 homozygotes make posterior somites, scattered notochord cells, and floorplate and achieve an allantoic connection. However, despite making a maternal connection, T2 homozygotes cease development at E11.5 and die soon after. We have cloned and analyzed the transgene insertion site, which maps within 100 kb of the Brachyury gene, but does not seem to physically interrupt nor affect transcription from that locus. The existence of a second gene mapping near Brachyury and affecting the same developmental processes was alluded to over 50 years ago and has been debated ever since. An embryological description of T2 is presented, as is a discussion of the implications of a single, larger Brachyury locus versus two closely linked genes coordinately regulating axial development.

Animals↗

Exploring genetic mapping and co-expression patterns to illuminate significance of Tbx20 in cardiac biology.

The transcription factor Tbx20 is integral to heart development and plays a significant role in various cardiac diseases. Despite its established importance, the regulatory mechanisms and functional significance of Tbx20 remain incompletely understood. To elucidate these mechanisms, we initially conducted eQTL mapping to identify genetic loci associated with Tbx20 expression in heart tissue from BXD mice. Co-expression and enrichment analyses revealed pathways linked to Tbx20, including dilated cardiomyopathy, hypertrophic cardiomyopathy, and FoxO signaling. Additionally, protein-protein interaction studies identified essential cardiac proteins, such as Myl2 and Myl7, along with upstream regulators like Mef2c. To validate our bioinformatic findings, we performed quantitative reverse transcription polymerase chain reaction (qRT-PCR) to assess the relative mRNA expression levels of TBX20 and Mef2c in the heart tissues of BXD mice compared to their parental strains (B6 and D2). Our results demonstrated significant up-regulation of both TBX20 and Mef2c in the BXD group relative to the parental strains. Conversely, both genes were down-regulated in B6, D2, Control, and Treatment groups when compared to BXD mice. These findings confirm the predicted regulatory roles of TBX20 and Mef2c in cardiac development as suggested by our initial analyses.This study not only reinforces the critical role of Tbx20 in cardiac gene regulation but also highlights its potential as a therapeutic target for cardiovascular disorders. Further investigations into Tbx20 and its interactions will enhance our understanding of heart biology and contribute to the development of targeted therapies for heart diseases.

Animals↗

An inflammatory bowel disease-linked lncRNA suppresses transcription factor T-BET expression in T cells to limit intestinal inflammation.

Among the tens of thousands of annotated long noncoding RNAs (lncRNAs) in the human genome, only a small fraction have been functionally characterized. Here, we show that a well-established inflammatory bowel disease (IBD) risk locus encoded a conserved lncRNA, lnc15 (2310015A10Rik/ENSMUSG00000097729), whose structure was destabilized by risk-associated variants, leading to its degradation. Deletion of lnc15 in mice resulted in molecular features of inflammation under steady-state conditions and conferred heightened susceptibility to experimental colitis. Lnc15 was abundantly expressed in T cells, with highest expression in regulatory T (Treg) cells. Mechanistically, lnc15 suppressed the transcription factor T-BET by recruiting the CCR4-NOT RNA degradation complex to Tbx21 mRNA. Our study identifies that lnc15 simultaneously enhances Treg cell suppressive function and impairs conventional T cell pathogenicity in the context of intestinal inflammation. Collectively, these findings identify lnc15 as a functional lncRNA that links noncoding genetic variation to immune regulation and prevention of mucosal inflammation. VIDEO ABSTRACT.

RNA, Long Noncoding↗