Biology subjects

Traver, D.

Publications and source records attributed to Traver, D..

8 recordsLinked to original sources

bioRxiv2022

Cross-species analysis identifies conserved transcriptional mechanisms of neutrophil maturation

Neutrophils are evolutionarily conserved innate defense cells implicated in diverse pathological processes. Zebrafish models have contributed substantially to our understanding of neutrophil functions, but similarities to human neutrophil maturation have not been characterized limiting applicability to study human disease. We generated transgenic zebrafish strains to distinguish neutrophil maturation grades in vivo and established a high-resolution transcriptional profile of neutrophil maturation. We linked gene expression at each stage to characteristic transcription factors, including C/ebp{beta}, important for late neutrophil maturation. Cross-species comparison of zebrafish, mouse, and human confirmed high molecular similarity in immature stages and discriminated zebrafish-specific from pan-species gene signatures. Applying pan-species neutrophil maturation signatures in RNA-seq data from neuroblastoma patients revealed an association of metastatic tumor cell infiltration in the bone marrow with an increase in mature neutrophils. Our detailed neutrophil maturation atlas provides a valuable resource for studying neutrophil function at different stages across species in health and disease. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=83 SRC="FIGDIR/small/518146v1_ufig1.gif" ALT="Figure 1"> View larger version (37K): org.highwire.dtl.DTLVardef@d46deaorg.highwire.dtl.DTLVardef@7c2647org.highwire.dtl.DTLVardef@b535eeorg.highwire.dtl.DTLVardef@e7dc38_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2020

A zebrafish model of Granulin deficiency reveals essential roles in myeloid cell differentiation

Granulin (GRN) is a pleiotropic protein involved in inflammation, wound healing, neurodegenerative disease, and tumorigenesis. These roles in human health have prompted research efforts to utilize Granulin in the treatment of rheumatoid arthritis, frontotemporal dementia, and to enhance wound healing. How granulin contributes to each of these diverse biological functions, however, remains largely unknown. Here, we have uncovered a new role for granulin during myeloid cell differentiation. Using a zebrafish model of granulin deficiency, we reveal that in the absence of granulin a (grna), myeloid progenitors are unable to terminally differentiate into neutrophils and macrophages during normal and emergency myelopoiesis. In addition, macrophages fail to recruit to the wound, resulting in abnormal healing. Our CUT&RUN experiments identify Pu.1, which together with Irf8 positively regulate grna expression. Importantly, we demonstrate functional conservation between the mammalian granulin and the zebrafish orthologue grna. Our findings uncover a previously unrecognized role for granulin during myeloid cell differentiation, opening a new field of study that has the potential to impact different aspects of the human health.

cell biology↗

bioRxiv2020

Dermomyotome-derived endothelial cells migrate to the dorsal aorta to support hematopoietic stem cell emergence

Development of the dorsal aorta is a key step in the establishment of the adult blood-forming system, since hematopoietic stem and progenitor cells (HSPCs) arise from ventral aortic endothelium in all vertebrate animals studied. Work in zebrafish has demonstrated that arterial and venous endothelial precursors arise from distinct subsets of lateral plate mesoderm. Earlier studies in the chick showed that paraxial mesoderm generates another subset of endothelial cells that incorporate into the dorsal aorta to replace HSPCs as they exit the aorta and enter circulation. Here we show that a similar process occurs in the zebrafish, where a population of endothelial precursors delaminates from the somitic dermomyotome to incorporate exclusively into the developing dorsal aorta. Whereas somite-derived endothelial cells (SDECs) lack hematopoietic potential, they act as local niche to support the emergence of HSPCs from neighboring hemogenic endothelium. Thus, at least three subsets of endothelial cells (ECs) contribute to the developing dorsal aorta: vascular ECs, hemogenic ECs, and SDECs. Taken together, our findings indicate that the distinct spatial origins of endothelial precursors dictate different cellular potentials within the developing dorsal aorta.

developmental biology↗

bioRxiv2019

In vivo lineage conversion of vertebrate muscle into early endoderm-like cells

The extent to which differentiated cells, while remaining in their native microenvironment, can be reprogrammed to assume a different identity will reveal fundamental insight into cellular plasticity and impact regenerative medicine. To investigate in vivo cell lineage potential, we leveraged the zebrafish as a practical vertebrate platform to determine factors and mechanisms necessary to induce differentiated cells of one germ layer to adopt the lineage of another. We discovered that ectopic co-expression of Sox32 and Oct4 in several non-endoderm lineages, including skeletal muscle, can specifically trigger an early endoderm genetic program in a cell-autonomous manner. Gene expression, live imaging, and functional studies reveal that the endoderm-induced muscle cells lose muscle gene expression and morphology, while specifically gaining endoderm organogenesis markers, such as the pancreatic specification genes, hhex and ptf1a, via a mechanism resembling normal development. Endoderm induction by a pluripotent defective form of Oct4, endoderm markers appearing prior to loss of muscle cell morphology, a lack of dependence on cell division, and a lack of mesoderm, ectoderm, dedifferentiation, and pluripotency gene activation, together, suggests that reprogramming is endoderm specific and occurs via direct lineage conversion. Our work demonstrates that within a vertebrate animal, stably differentiated cells can be induced to directly adopt the identity of a completely unrelated cell lineage, while remaining in a distinct microenvironment, suggesting that differentiated cells in vivo may be more amenable to lineage conversion than previously appreciated. This discovery of possibly unlimited lineage potential of differentiated cells in vivo challenges our understanding of cell lineage restriction and may pave the way towards a vast new in vivo supply of replacement cells for degenerative diseases such as diabetes.

developmental biology↗

bioRxiv2019

Endothelial struts, a mechanism to generate large lumenized blood vessels de novo

Lumenization of de novo formed blood vessels occurs either through cell hollowing (intracellular lumen)1-3 or cord hollowing (extracellular lumen)4-6 and restricts thereby the initial lumen diameter to one or two endothelial cells (ECs) respectively. However, vasculogenesis can result in large diameter blood vessels, raising the question how these vessels are formed. Here, we describe an alternative model of vasculogenesis that results in the formation of large diameter vessels. In this model, ECs coalesce into a branched network of EC struts within the future lumen of the vessel. These struts maintain the patency of the vessel and serve as a scaffold for the ECs forming the vessel wall, which initially consists out of a few patches of ECs. Together, we show that endothelial struts facilitate the formation of large blood vessels without being bound by the prerequisite of a cord-like structure, nor are they restricted in size.

developmental biology↗

bioRxiv2019

Direct Visualization of Live Zebrafish Glycan via Single-step Metabolic Labeling with Fluorophore-tagged Nucleotide Sugars

Dynamic turnover of cell-surface glycans is involved in a myriad of biological events, making this process an attractive target for in vivo molecular imaging. The metabolic glycan labeling coupled with bioorthogonal chemistry has paved the way for visulizing glycans in living organisms. However, a two-step labeling sequence is required, which is prone to tissue penetration difficulties of the imaging probes. Here, by exploring the substrate promiscuity of endogenous glycosyltransferases, we developed a single-step fluorescent glycan labeling strategy by using fluorophore-tagged analogs of nucleotide sugars directly. Injecting the fluorophore-tagged sialic acid and fucose into the yolk of zebrafish embryos at the one-cell stage enables a systematic imaging of sialylation and fucosylation in live zebrafish embryos at various developmental stages. From these studies, we obtained insights into the role of sialylated and fucosylated glycans in zebrafish hematopoiesis.

biochemistry↗

bioRxiv2018

EGFR confers exquisite specificity of Wnt9a-Fzd9b signaling in hematopoietic stem cell development

The mechanisms of Wnt-Frizzled (Fzd) signaling selectivity and their biological implications remain unclear. We demonstrate for the first time that the epidermal growth factor receptor (EGFR) is required as a co-factor for Wnt signaling. Using genetic studies in zebrafish, paired with in vitro cell biology and biochemistry, we have determined that Fzd9b signals specifically with Wnt9a in vivo and in vitro to elicit {beta}-catenin dependent Wnt signals that regulate hematopoietic stem and progenitor cell (HSPC) development in the dorsal aorta. This requirement is conserved in the derivation of HSPCs from human embryonic stem cells. Wnt9a-Fzd9b specificity requires two intracellular domains in Fzd9b, which interact with EGFR as a required co-factor to promote signal transduction. EGFR phosphorylates one tyrosine residue on Fzd9b, a requirement for the Wnt signal. These findings indicate that Wnt signaling interactions can be exquisitely specific and inform protocols for derivation of HSPCs in vitro.\n\nHighlightsO_LIAn in vitro signaling screen identifies Fzd9b as a Wnt9a-specific receptor.\nC_LIO_LIFzd9b and Wnt9a regulate hematopoietic stem cell development as a cognate pair.\nC_LIO_LIWNT9A and FZD9 are required for HSPC derivation from human pluripotent cells in vitro.\nC_LIO_LIEGFR confers specificity to Wnt9a-Fzd9b signaling in zebrafish and human cells.\nC_LI

developmental biology↗

bioRxiv2016

Blood flow directs arterial-venous remodeling through Notch activation and endothelial cell migration

Arteries and veins are formed independently by different types of endothelial cells (ECs). In vascular remodeling, arteries and veins become connected and some arteries become veins. It is unclear how ECs in transforming vessels change their type and how fates of individual vessels are determined. In embryonic trunk, vascular remodeling transforms arterial intersegmental vessels (ISVs) into a functional network of arteries and veins. We found that, once an ISV is connected to venous circulation, venous blood flow promotes upstream migration of ECs that results in displacement of arterial ECs by venous ECs, completing the transformation of this ISV into a vein without trans-differentiation of ECs. Arterial blood flow initiated in two neighboring ISVs prevents their transformation into veins by activating Notch signaling in ECs. Together, different responses of ECs to arterial and venous blood flow lead to the formation of a balanced network with equal numbers of arteries and veins.

developmental biology↗