Biology subjects

Yaniv, K.

Publications and source records attributed to Yaniv, K..

12 recordsLinked to original sources

bioRxiv2026

Vascular specification from diversified mesoderm culminates in endothelial convergence

Vasculogenesis establishes the embryonic circulatory system, yet how a common vascular program emerges across multiple embryonic and extraembryonic developmental environments remains incompletely understood. Here, we reconstruct mouse vasculogenesis through integrated single-cell, spatial, lineage and perturbation analyses. We find that vascular specification emerges from distinct sources of pre-specified mesoderm through a transient Kdr+Etv2- vascular-primed state promoted by BMP signaling. Primed cells persist until E8.0- E8.5, after which they resolve into committed derivatives. Dual blood-endothelial potential is largely restricted to early vitelline progenitors, whereas embryonic and umbilical progenitors contribute predominantly to endothelial lineages. Temporal VEGF signaling perturbations validate the inferred specification sequence, placing VEGF downstream of vascular priming and demonstrating its indispensable role in vascular and primitive blood specification. Unlike most developmental lineages, endothelial derivatives converge toward a common transcriptional state while retaining transcriptional traces of their developmental origins. Together, these findings establish a mechanistically validated developmental sequence for mammalian vasculogenesis.

developmental biology↗

bioRxiv2026

Conserved and divergent programs govern cerebellar output neuron development in zebrafish

Cerebellar output neurons transmit the results of cerebellar computation to other brain regions. In most vertebrates, cerebellar output neurons form discrete nuclei, whereas in teleosts they are represented by eurydendroid cells, which differ markedly in morphology and anatomical organization. How these divergent output systems are developmentally related remains unclear. Here, we show that zebrafish eurydendroid cells arise from atoh1a-expressing progenitors, including a population expressing olig2, revealing a developmental origin shared with cerebellar output neurons in other vertebrates. atoh1a is required for eurydendroid cell differentiation and regulates lhx9 and lhx2b, which promote robo1 and robo3 expression and proper axon guidance. Our findings also suggest a role for Reelin signaling in eurydendroid cell positioning. Together, these findings reveal conserved developmental features shared by cerebellar output neurons across vertebrates, as well as mechanisms underlying the distinct anatomical organization of teleost eurydendroid cells.

developmental biology↗

bioRxiv2025

Ferroptosis governs lymphatic vessel growth and regression

Whether, when, and how lymphatic vessels undergo cell death remains poorly understood. Here we identify ferroptosis as a physiological, cell-intrinsic regulator of the lymphatic endothelial cell survival during development and following injury, in stark contrast to the resilient organotypic blood endothelial cells. The lymphatic susceptibility to ferroptosis stems from tampered cystine/ hydropersulfide metabolism, alongside reduced glutathione availability triggered by an SH3RF3 E3 ligase mediated GPX4 degradation, and enhanced integration of polyunsaturated fatty acid enriched membrane phospholipids. Inducing ferroptosis genetically or pharmacologically elevated lymphatic lipid peroxidation, halted embryonic lymphangiogenesis and prevented post-injury lymphatic overgrowth while simultaneously shaped immune responses. Conversely, ferroptosis inhibition through saturated fatty acid supplementation led to pathological lymphatic hyperplasia. Targeting lymphatic ferroptotic mechanisms holds promise against pathological lymphatic growth in response to injury.

cell biology↗

bioRxiv2025

Deciphering the Origin and Plasticity of Circulating Endothelial Cells: A Model for Systemic Angiogenesis Programs in Health and Disease

Endothelial cells line the inner surface of blood and lymphatic vessels and play key roles in vascular function. Circulating endothelial cells (CECs) are endothelial cells found in the bloodstream, yet their origin and functional potential have not been fully elucidated. To investigate their identity, we assembled and analyzed multiple public single-cell gene expression atlases comprising 212,144 endothelial cells from 23 human tissues. Using these datasets, we identified gene modules that quantitatively resolve endothelial types and states, including arterial, capillary, venous, lymphatic, and angiogenic-state programs, along with genes that are unique to endothelial cells of specific tissues. Leveraging this knowledge to 597 CECs, which we isolated from 2.1 million circulating CD34 cells across 287 donors, we found that CECs span a wide spectrum of mature endothelial identities and tissue-specific programs, consistent with diverse vascular origins. In culture, CECs downregulate mature endothelial markers (e.g., CD34) and acquire a progenitor-like PROCR transcriptional expression. Alteration of the Notch signaling in-vitro reverses this shift, with indirect activation of the pathway inducing a capillary and angiogenic program reminiscent of mature endothelial cells. As we profiled the angiogenic program in-vivo and created an in-vitro angiogenic EC model, we sought to determine whether similar transcriptional programs are present in the context of cancer. We analyzed publicly available single-cell RNA-seq datasets from normal and malignant breast tissue, uncovering a marked enrichment of angiogenic endothelial cells not only within the tumor but, surprisingly, also in histologically normal contralateral breast tissue from breast cancer patients, pointing to a previously unrecognized systemic paraneoplastic effect. Transcriptomic overlap between these in-vivo angiogenic cells and Notch-biased cultured CEC derivatives suggests that CEC cultures may serve as an accessible human model for tumor-driven and paraneoplastic vascular remodeling. Together, our study introduces a comprehensive framework for deciphering endothelial cell identity, illuminates CEC origin and plasticity, and provides a scalable platform to study cancer-associated endothelial reprogramming.

molecular biology↗

bioRxiv2025

A Conserved Venous Remodeling Program Governs Inferior Vena Cava Formation in Zebrafish

The Inferior Vena Cava (IVC), the largest venous conduit in mammals, forms through complex remodeling of the embryonic cardinal veins (CVs), a process prone to congenital anomalies, with significant clinical implications. However, the mechanisms underlying IVC formation remain unclear. Here, we identify a conserved IVC in zebrafish that emerges during metamorphosis through remodeling of the embryonic CVs, mirroring the mammalian process. Using in vivo imaging and clonal lineage tracing, we identify the cellular origins and molecular mechanisms controlling IVC formation and demonstrate that the transition from CV to IVC represents a shift from a multifunctional embryonic vein to a specialized adult conduit adapted for high-volume blood return. Overall, our findings illuminate conserved mechanisms of venous remodeling and establish a foundation for investigating congenital venous anomalies.

developmental biology↗

bioRxiv2024

A high-throughput zebrafish screen identifies novel candidate treatments for Kaposiform Lymphangiomatosis (KLA)

Kaposiform Lymphangiomatosis (KLA) is a rare, aggressive, and incurable disease caused by a somatic activating NRAS mutation (p.Q61R) in lymphatic endothelial cells (LECs). The development of new therapeutic avenues is hampered by the lack of animal models faithfully replicating the clinical manifestations of KLA. Here, we established a novel zebrafish model of KLA by driving conditional expression of the human NRAS mutation in venous and lymphatic ECs. We find that mutant embryos recapitulated clinical features of KLA, including pericardial edema and a dilated thoracic duct, and that the phenotypes were reverted by Trametinib, a MEK inhibitor used for KLA treatment. We further leverage this model in combination with an AI-based high-throughput drug screening platform to search for small compounds selectively reverting the mutant phenotypes and identify Cabozantinib, an FDA-approved tyrosine kinase inhibitor, and GSK690693, a competitive pan-Akt kinase inhibitor, as leading hits. Finally, we test these drugs in cultured cells derived from KLA patient and demonstrate their ability to normalize LEC sprouting and block NRAS downstream pathways, underscoring the potential of GSK690693 and Cabozantinib as potential KLA treatments. Overall, our novel zebrafish model provides a valuable tool for research into the etiology of KLA and for identifying new therapeutic avenues.

developmental biology↗

bioRxiv2023

Endolysosomal dysfunction in radial glia progenitor cells leads to defective cerebral angiogenesis and compromised Blood-Brain Barrier integrity

The neurovascular unit (NVU) is a complex structure comprising neurons, glia, and pericytes that interact with specialized endothelial cells to maintain cerebral homeostasis and blood-brain barrier (BBB) integrity. Alterations to NVU formation and function can lead to serious forms of cerebrovascular disease, including cerebral small vessel diseases (CSVDs), a range of pathological changes of cerebral capillaries within the white matter contributing to BBB dysfunction and demyelination. Despite the growing recognition of the pivotal roles played by neuro-vascular and glia-vascular interfaces in NVU formation and functioning, CSVD research has mainly focused on characterizing pericyte and EC dysfunction, leaving our understanding of the contribution of non-vascular cells of the brain parenchyma limited. Here, we use a novel zebrafish mutant to delve into the intricate interplay among NVU components and demonstrate how the compromised specification of a progenitor cell population sets off a cascade of events, ultimately leading to severe cerebrovascular abnormalities. The mutation affects Scavenger Receptor B2 (scarb2)/Lysosomal Membrane Protein 2 (limp2), a highly conserved protein residing in the membrane of late endosomes and lysosomes. We find Scarb2 to be predominantly expressed in Radial Glia Cells (RGCs), a multipotent cell giving rise to neurons and glia in both zebrafish and mammals. Through live imaging and genetic manipulations, we identify impaired Notch3 signaling in RGCs and their glial progeny as the primary consequence of Scarb2a depletion and show that this disruption causes excessive neurogenesis at the expense of glial cell differentiation. We further pinpoint compromised acidification of the endolysosomal compartment in mutant cells as the underlying cause of disrupted Notch3 processing, linking for the first time Notch3 defects in non-vascular cells of the brain parenchyma to CSVD phenotypes. Given the evolutionary conservation of SCARB2 expression and the remarkable recapitulation of CSVD phenotypes, scarb2 mutants provide a promising framework for investigating the mechanisms governing Notch3 processing in non-vascular cells and their involvement in the onset of CSVD.

developmental biology↗

bioRxiv2021

Generation of specialized blood vessels through transdifferentiation of lymphatic endothelial cells

The lineage and developmental trajectory of a cell are key determinants of cellular identity. Yet, the functional relevance of deriving a specific cell type from ontologically distinct progenitors, remains an open question. In the case of the vascular system, blood and lymphatic vessels are composed of endothelial cells (ECs) that differentiate and diversify to cater the different physiological demands of each organ. While lymphatic vessels have been shown to originate from multiple cell sources, lymphatic ECs (LECs) themselves seem to have a unipotent cell fate. In this work we uncover a novel mechanism of blood vessel formation through transdifferentiation of LECs. Using advanced long-term reiterative imaging and lineage-tracing of ECs in zebrafish, from embryonic development through adulthood, we reveal a hitherto unknown process of LEC-to-BEC transdifferentiation, underlying vascularization of the anal fin (AF). Moreover, we demonstrate distinct functional implications for deriving AF vessels from either LECs or BECs, uncovering for the first time a clear link between cell ontogeny and functionality. Molecularly, we identify Sox17 as a negative regulator of lymphatic fate specification, whose specific expression in AF LECs suppresses its lymphatic cell fate. Finally, we show that akin to the developmental process, during adult AF regeneration the vasculature is re-derived from lymphatics, demonstrating that LECs in the mature fish retain both potency and plasticity for generating specialized blood vessels. Overall, our work highlights a novel mechanism of blood vessel formation through LEC trans-differentiation, and provides the first in vivo evidence for a link between cell ontogeny and functionality in ECs.

developmental biology↗

bioRxiv2021

Novel zebrafish mutants reveal new roles for Apolipoprotein B during embryonic development and pathological conditions

Apolipoprotein B (ApoB) is the primary protein of chylomicrons, VLDLs and LDLs and is essential for their assembly. Defects in ApoB synthesis and secretion result in several human diseases, including abetalipoproteinemia and familial hypobetalipoproteinemia. Conversely, high levels of APOB in plasma are associated with increased risk for coronary heart disease and atherosclerosis. The involvement of APOB in lipid metabolism and atherogenesis prompted the generation of several mutant mice. However, as APOB is required for supplying nutrients to the developing embryo, ApoB null mice are embryonic lethal, thereby precluding the study of the roles of this protein during development. Here, we established novel zebrafish mutants for two apoB genes: apoBa and apoBb.1. Double-mutant embryos display clear hallmarks of human hypolipidemia-related diseases, including intestinal defects and fatty liver, as well as profound vascular defects. We further use these models to identify the domains within ApoB responsible for its functions. By assessing the ability of different truncated forms of human APOB to rescue the mutant phenotypes, we demonstrate the benefits of this model for prospective therapeutic screens. Overall, our novel zebrafish models uncover new functions of ApoB in organ development and morphogenesis and shed new light on the mechanisms underlying hypolipidemia-related diseases.

developmental biology↗

bioRxiv2020

An inside look at a biofilm: Pseudomonas aeruginosa flagella bio-tracking

The opportunistic pathogen, Pseudomonas aeruginosa, a flagellated bacterium, is one of the top model organisms for studying biofilm formation. In order to elucidate the role of the bacteria flagella in biofilm formation, we developed a new tool for flagella bio-tracking. We have site-specifically labeled the bacterial flagella by incorporating an unnatural amino acid into the flagella monomer via genetic code expansion. This enabled us to label and track the bacterial flagella during biofilm maturation. Direct, live imaging revealed for the first-time presence and synthesis of flagella throughout the biofilm lifecycle. To ascertain the possible role of the flagella in the strength of a biofilm we produced a "flagella knockout" strain and compared its biofilm to that of the wild type strain. Results showed a one order of magnitude stronger biofilm structure in the wild type in comparison to the flagella knockout strain. This suggests a newly discovered structural role for bacterial flagella in biofilm structure, possibly acting as a scaffold. Based on our findings we suggest a new model for biofilm maturation dynamic and underscore the importance of direct evidence from within the biofilm.

microbiology↗

bioRxiv2020

VEGFC induced cell cycle arrest mediates sprouting and differentiation of venous and lymphatic endothelial cells

The emergence and growth of new vessels requires a tight synchronization between proliferation, differentiation and sprouting, traditionally thought to be controlled by mitogenic signals, especially of the VEGF family. However, how these cues are differentially transduced, by sometimes even neighboring endothelial cells (ECs), remains unclear. Here we identify cell-cycle progression as a new regulator of EC sprouting and differentiation. Using transgenic zebrafish illuminating cell-cycle stages, we show that venous and lymphatic precursors sprout from the Cardinal Vein (CV) exclusively in G0/G1, and reveal that cell-cycle arrest is induced in these ECs by p53 and the CDK-inhibitors p27 and p21. Moreover, we demonstrate that in vivo, chemical and genetic cell-cycle inhibition, results in massive vascular growth. Mechanistically, we identify the mitogenic VEGFC/VEGFR3/ERK axis as direct inducer of cell-cycle arrest in angiogenic ECs and characterize the cascade of events governing venous vs. lymphatic segregation and sprouting. Overall, our results uncover an unexpected mechanism whereby mitogen-controlled cell-cycle arrest boosts sprouting, raising important questions about the use of cell-cycle inhibitors in pathological angiogenesis and lymphangiogenesis.

developmental biology↗

bioRxiv2019

BACH family members regulate angiogenesis and lymphangiogenesis by modulating VEGFC expression

Angiogenesis and lymphangiogenesis are key processes during embryogenesis as well as under physiological and pathological conditions. Vascular endothelial growth factor C (VEGFC), the ligand for both VEGFR2 and VEGFR3, is a central lymphangiogenic regulator that also drives angiogenesis. Here we report that members of the highly conserved BACH (BTB and CNC homology) family of transcription factors regulate VEGFC expression, through direct binding to its promoter. Accordingly, downregulation of bach2a hinders blood-vessel formation and impairs lymphatic sprouting in a vegfc-dependent manner during zebrafish embryonic development. In contrast, BACH1-overexpression enhances intratumoral blood-vessel density and peritumoral lymphatic vessel diameter in ovarian and lung mouse tumor models. The effects on the vascular compartment correlate spatially and temporally with BACH1 transcriptional regulation of VEGFC expression. Altogether, our results uncover a novel role for the BACH/VEGFC signaling axis in lymphatic formation during embryogenesis and cancer, providing a novel potential target for therapeutic interventions.

developmental biology↗