Biology subjects

Fantin, A.

Publications and source records attributed to Fantin, A..

9 recordsLinked to original sources

bioRxiv2026

A Csf1r lineage gives rise to dermal lymphatic endothelial cells

Lymphatic vessels are formed during embryonic and postnatal development to facilitate interstitial fluid clearance and immune regulation after birth. Their organ-specific heterogeneity in organisation and function is preceded by heterogenous origins of lymphatic endothelial cells (LECs), the main building blocks of lymphatic vessels. In the dermis, a subset of LECs was reported to arise from blood capillaries, which themselves differentiate, in part, from paraxial mesoderm. However, it is not known whether additional cell lineages contribute to the dermal LEC population. Here, we have combined transcriptomic analyses with genetic lineage tracing and wholemount immunostaining to show that 60% of LECs in the embryonic day (E) 13.5 and E15.5 dermis are derived from a cell lineage that expresses Csf1r, a marker of myeloid cells and their progeny. Csf1r lineage LECs persist in adult dermal lymphatic vasculature and are indispensable for normal lymphatic development, because Prox1 deletion within the Csf1r lineage causes dermal oedema and blood-filled lymphatic vessels. As Csf1r lineage dermal LECs do not themselves express Csf1r and also do not arise from Csf1r-expressing differentiated myeloid cells, our findings imply the existence of a Csf1r-expressing non-LEC precursor population for the majority of dermal LECs and will prompt further work to identify this cell population.

developmental biology↗

bioRxiv2024

Hemogenic endothelium of the vitelline and umbilical arteries is the major contributor to mouse fetal lympho-myelopoiesis

Embryonic hematopoiesis consists of distinct waves originating in rapid succession from different anatomical locations. Hematopoietic progenitors appearing earlier than definitive hematopoietic stem cells (HSCs) play key roles in fetal and postnatal life. However, their precise origin, identity and the extent of their contribution need further clarification. To this aim, we took advantage of a genetic fate-mapping strategy in mice that allows labeling and tracking of distinct subsets of hemogenic endothelium (HE). Time-course labeling of hematopoietic progenitors emerging from HE between E8.5 and E9.5, before intra-embryonic definitive HSC generation, revealed a major fetal lympho-myeloid contribution which declined in the adult. Lineage tracing coupled with whole-mount imaging and single-cell RNA sequencing located its source within hematopoietic clusters of vitelline and umbilical arteries. Functional assays confirmed the transient nature of these progenitors. We therefore unveiled a hitherto unidentified early wave of fetal-restricted hematopoietic stem/progenitor cells poised for differentiation that provide a major contribution to pre-natal hematopoiesis.

developmental biology↗

bioRxiv2024

A Pax3 lineage gives rise to transient haematopoietic progenitors

During embryonic development, muscle tissues, skin, and a subset of vascular endothelial cells arise from Pax3-expressing embryonic progenitors defined as paraxial mesoderm. By contrast, haemogenic potential is well established for extra-embryonic mesoderm and intra-embryonic lateral plate mesoderm which do not express Pax3. To date, it is not known whether the haematopoietic system also contains Pax3 lineage cells. Here, we show that the mouse foetal liver and foetal circulation contain a transient population of Pax3 lineage cells with hallmarks of haematopoietic progenitors and the potential to generate both myeloid and erythroid cells. We propose that Pax3 lineage haematopoietic cells should be investigated to better understand normal haematopoietic development from different mesodermal derivatives. Further, genetic alterations of Pax3 lineage haematopoietic cells should be investigated for their potential to cause haematopoietic malignancies.

developmental biology↗

bioRxiv2024

NRP1-expressing myeloid cells promote arteriogenesis in the ischemic limb

Peripheral arterial disease can cause limb threatening blood flow restriction, requiring amputation in up to a third of patients despite contemporary treatments. Stimulating new blood vessel growth in ischemic limbs using growth factors such as VEGF-A or supplying mixed cell populations via autologous transplantation has been investigated as a therapy for surgically intractable cases, but to date has proven ineffective in randomised controlled clinical studies. To identify more potent pro-arteriogenic cell populations, we have investigated VEGF-A responsive myeloid cell populations in a mouse model of severe hindlimb ischemia. We found that NRP1 ablation from monocytes and macrophages impaired arteriogenesis in the adductor muscle and flow recovery in the injured limb. Vice versa, the exogenous delivery of NRP1-expressing (but not NRP1-negative) macrophages enhanced arteriogenesis in the adductor and flow recovery in the ischemic limb in a VEGF signalling-dependent manner. Further, patient-derived NRP1-expressing monocytes promoted vascular morphogenesis ex vivo. As the levels of circulating NRP1-expressing monocytes were raised in patients with limb ischemia, the therapeutic delivery of autologous NRP1-expressing monocytes could be explored as a treatment for critical limb ischemia.

pathology↗

bioRxiv2023

Targeting NRP1 with EG00229 induces neurovascular permeability

NRP1 is a therapeutic target for inhibiting vascular endothelial growth factor (VEGF)-induced blood vessel dysfunction. The small molecule EG00229 was designed to inhibit VEGF binding to NRP1 and reduce pathological blood vessel growth. However, it is unknown whether EG00229 could also be used to reduce VEGF164-induced vascular leakage, which often exacerbates ischemic diseases due to VEGF upregulation. Here, we show that prior treatment with EG00229 prevents VEGF164-induced vascular permeability signalling, but, unexpectedly, also find that EG00229 increased rather than inhibited vascular leakage. Thus, EG00229 increased vascular leakage either when added alone or concurrently with VEGF164, both in perfused retinal explants and across primary brain EC monolayers. This EG00229-induced vascular leakage was not an off-target effect, because it relied on endothelial NRP1 expression and NRP1s VEGF164 binding pocket, yet was independent of VEGFR1 and VEGFR2. Moreover, EG00229 activated molecular events typical of VEGF164-induced paracellular permeability, including p38 MAP kinase (p38) and SRC family kinase (SFK) phosphorylation as well as CDH5 rearrangement in endothelial junctions. Investigating EG00229-induced signalling therefore helps elucidate NRP1-dependent mechanisms of paracellular permeability induction and might help identifying new approaches to modulate the neurovascular barrier.

physiology↗

bioRxiv2023

BulkECexplorer: a bulk RNAseq compendium of five endothelial subtypes that predicts whether genes are active or leaky

Transcriptomic data obtained by single cell (sc) RNAseq or bulk RNAseq can be mined to understand the molecular activity of cell types. Yet, lowly expressed but functional genes may remain undetected in RNAseq experiments for technical reasons, such as insufficient read depth or gene drop out in scRNAseq assays. By contrast, bulk RNAseq assays may detect lowly expressed mRNA transcripts thought to be the biologically irrelevant products of leaky transcription. To more accurately represent a cells functional transcriptome, we propose compiling many bulk RNAseq datasets into a compendium and applying established classification models to predict whether the detected genes are likely active or leaky in that cell type. Here, we have created such a compendium for vascular endothelial cells from several mouse and human organs, termed the BulkECexplorer.

bioinformatics↗

bioRxiv2023

A refined single cell landscape of haematopoiesis in the mouse foetal liver

During prenatal life, the foetal liver is colonised by several waves of haematopoietic stem and progenitor cells (HSPCs) to act as the main haematopoietic organ. Single cell (sc) RNA-seq has been used to identify foetal liver cell types via their transcriptomic signature and to compare gene expression pattern as haematopoietic development proceeds. To obtain a refined single cell landscape of haematopoiesis in the foetal liver, we have generated a novel scRNA-seq dataset from whole mouse E12.5 liver that includes a larger number of cells than prior datasets at this stage and was obtained without cell type preselection to include all liver cell populations. We combined mining of this dataset with that of previously published datasets at other developmental stages to follow transcriptional dynamics as well as cell cycle state of developing haematopoietic lineages. Our findings corroborate several prior reports on the timing of liver colonisation by HSPCs and the emergence of differentiated lineages and provide further molecular characterisation of each cell population. Extending these findings, we demonstrate the existence of a foetal intermediate haemoglobin profile in the mouse, similar to that previously identified in humans, and a previously unidentified population of primitive erythroid cells in the foetal liver.

developmental biology↗

bioRxiv2022

Metformin antiproliferative activity is exclusively mediated by the membrane functional expression of the Chloride Intracellular Channel 1 in glioblastoma stem cells

Metformin is the first-line drug for type-2 diabetes. Retrospective analyses, based on diabetic patients clinical data, demonstrate that daily assumption of metformin reduces the incidence of several kinds of solid tumors. Even though it is widely agreed that metformin must be internalized to accomplish its pharmacological activity, direct evidence about metformin membrane permeability and/or the presence of a specific membrane receptor in cancer cells is still missing. Here, we show that the transmembrane form of Chloride Intracellular Channel 1 (tmCLIC1) works as a privileged metformin receptor in glioblastoma stem-like cells. We found that metformin impairs tmCLIC1 activity by a specific binding coordinated by arginine 29. Its mutation, preventing metformin to bind and block tmCLIC1, abolishes the biguanide inhibition of glioblastoma cell proliferation in 2D and 3D models and metformin dependent effect on mitochondrial respiration. In addition, we demonstrate the direct binding between the drug and its target, and by in vivo experiments on zebrafish embryos and mice orthotopically engrafted with glioblastoma cells and treated with metformin, we prove that metformin binding to tmCLIC1 is crucial for metformin antineoplastic effect. Considering tmCLIC1s contribution to glioblastoma progression, the present work provides the fundaments for future development of strategies aimed at improving metformin-tmCLIC1 interaction to further increase metformin therapeutic potential.

cancer biology↗

bioRxiv2021

KIT is required for fetal liver erythropoiesis but dispensable for angiogenesis

Blood vessels are fundamental to sustain organ growth and tissue metabolism. In the mouse embryo, endothelial cell (EC) progenitors almost concomitantly give rise to the first blood vessels in the yolk sac and the large vessels of the embryo proper. Thereafter, the vascular network expands by angiogenesis to vascularize developing organs such as the brain. Although the first blood cells form in the yolk sac before blood vessels have assembled, consecutive waves of hematopoietic progenitors subsequently bud from hemogenic endothelium located within the wall of yolk sac and large intraembryonic vessels in a process termed endothelial to hematopoietic transition (endoHT). The receptor tyrosine kinase KIT is required for late embryonic erythropoiesis, but KIT is also expressed earlier in the hemogenic endothelium, in hematopoietic progenitors that arise via endoHT from hemogenic endothelium and non-hemogenic ECs, such as in the brain. However, it remains unclear whether KIT has essential roles in early hematopoiesis or even blood vessel growth. Here, we have combined transcriptomic analysis to delineate Kit expression with the analysis of knockout mice to show that KIT is expressed during but dispensable for yolk sac endoHT or brain angiogenesis but required for transient definitive erythropoiesis in the fetal liver.

developmental biology↗