Biology subjects

Tosato, G.

Publications and source records attributed to Tosato, G..

5 recordsLinked to original sources

bioRxiv2025

Single-cell lineage tracing identifies hemogenic endothelial cells in the adult mouse bone marrow

During mouse development, hematopoietic stem and progenitor cells (HSPC) originate from hemogenic endothelial cells (ECs) through a process of endothelial-to-hematopoietic transition. These HSPC are thought to fully sustain adult hematopoiesis. However, it remains unknown whether adult ECs retain hemogenic potential. Here we used in vivo genetic lineage tracking at population and single-cell (sc) levels, scRNA sequencing, and bone marrow transplantation to detect hemogenic ECs in adult mice. We identify and characterize bone marrow-resident, adult Cdh5/VE-Cadherin+ ECs that produce hematopoietic cell-progeny in vitro and in mice. These adult hemogenic ECs and their hematopoietic cell progeny give rise to hematopoietic cells following adoptive transfer into adult mice. Furthermore, blood cells generated from adult and developmental ECs comparably home to peripheral tissues, where they similarly contribute to inflammatory responses. Thus, our results identify previously unrecognized bone marrow-derived adult hemogenic ECs that generate HSPC and functional mature blood cells.

cell biology↗

bioRxiv2022

Bone marrow hemogenic endothelial cells contribute multilineage hematopoietic progenitors in adult mice

During development, hematopoietic stem/progenitor cells (HSPCs) originate from a subset of hemogenic endothelial cells (ECs) through a process of endothelial-to-hematopoietic transition (EHT). This process is temporally restricted to short developmental windows and generates HSPC with distinct capabilities for hematopoiesis. Although it is generally thought that adult hematopoiesis is sustained by HSCs derived from hemogenic endothelium during development, some observations point to EHT persistence in the late fetus/perinatally. Here we use lineage tracking and bioinformatics analysis to assess the presence of hemogenic endothelial cells in the adult mouse. Our analysis identifies a subset of bone marrow-resident adult endothelial cells, characterized by the expression of VE-Cadherin and the transcription factor RUNX1, that produce CD45+ hematopoietic cells. This EHT generates hematopoietic progenitors, and mature myeloid and lymphoid cells in the adult mouse. Our results reveal the identification of a distinct source of adult blood.

cell biology↗

bioRxiv2020

Targeting the SHP2 phosphatase promotes vascular damage and inhibition of tumor growth

The tyrosine phosphatase SHP2 is oncogenic in cancers driven by receptor-tyrosine-kinases, and SHP2 inhibition reduces tumor growth. Here, we report that SHP2 is an essential promoter of endothelial cell survival and growth in the remodeling tumor vasculature. Using genetic and chemical approaches to inhibit SHP2 activity in endothelial cells, we show that SHP2 inhibits pro-apoptotic STAT3 and stimulates proliferative ERK1/2 signaling. Systemic SHP2 inhibition in mice bearing tumors selected for SHP2-independent tumor-cell growth, promotes degeneration of the tumor vasculature and blood extravasation; reduces tumor vascularity and blood perfusion; and increases tumor hypoxia and necrosis. Reduction of tumor growth ensues, independent of SHP2 targeting in the tumor cells, blocking immune checkpoints or recruiting anti-tumor macrophages. We also show that inhibiting the Angiopoietin/TIE2/AKT cascade magnifies the vascular and anti-tumor effects of SHP2 inhibition by blocking tumor endothelial AKT signaling, not a target of SHP2. Since the SHP2 and Ang2/TIE2 pathways are active in vascular endothelial cells of human melanoma and colon carcinoma, SHP2 inhibitors alone or with Ang2/Tie2 inhibitors hold promise to effectively target the tumor endothelium.

cancer biology↗

bioRxiv2020

Iterative Epigenomic Analyses in the Same Single Cell

Gene expression in individual cells is epigenetically regulated by DNA modifications, histone modifications, transcription factors and other DNA-binding proteins. It has been shown that multiple histone modifications can predict gene expression and reflect future responses of bulk cells to extracellular cues. However, the predictive ability of epigenomic analysis is still limited for mechanistic research at a single cell level. To overcome this limitation, it is useful to acquire reliable signals from multiple epigenetic marks in the same single cell. Here, we propose a new approach for analysis of several components of the epigenome in the same single cell. The new method allows reanalysis of the same single cell. We found that reanalysis of the same single cell is feasible, and provides confirmation of the signals and allows application of statistical analysis to identify reliable signals using data sets generated only from the single cell. Reanalysis of the same single cell is also useful to acquire multiple-epigenetic marks from the same single cells. The method can acquire at least 4 epigenetic marks, H3K27ac, H3K27me3, mediator complex subunit 1 and a DNA modification. We predicted active signaling pathways in K562 single cells using the data. We confirmed that the prediction results showed a strong correlation with actual active signaling pathways shown by RNA-seq results. These results suggest that the new approach provides mechanistic insights for cellular phenotypes through multi-layered epigenome analysis in the same single cells.

genomics↗

bioRxiv2019

The molecular landscape and microenvironment of salivary duct carcinoma reveal new therapeutic opportunities

Salivary duct carcinoma (SDC) is a rare and aggressive salivary gland cancer subtype with poor prognosis. The mutational landscape of SDC has been described rather exhaustively; yet, with respect to functional genomics and tumor microenvironment, little is known. In this study, transcriptomics and proteomics were combined to obtain the first characterization of the pathways deregulated in SDC. The data revealed the importance of Notch, TGB-{beta}, and interferon-{gamma} signaling. After associating computational biology, immunohistochemistry, multiplexed immunofluorescence, and digital imaging the first steps towards charting the cellular network within the microenvironment was initiated. According to immune infiltrate, two well-defined groups of tumors were observed, novel SDC immune checkpoints were discovered, and the key role played by macrophages and potentially NK cells in immunosuppression was shown. Furthermore, a clear trend between recurrence-free survival and M2 macrophage abundance was apparent. Independently, a measure of desmoplastic stromal reaction as determined by -SMA abundance, was also shown. Altogether, these many findings open new perspectives for understanding and treating SDC. Before applying an immunotherapy, classical patient stratification according to immune infiltrate should be taken into account. Moreover, the microenvironment offers new potential targets including macrophages or NK cells, or even fibroblasts or hyaluronic acid. Related therapies that have been developed against, e.g., pancreatic tumors could inspire equivalent therapy for SDC.\n\nAdditional informationO_LIFinancial support: MA (1 grant, GIRCI SOOM API-K 2016-811-DRC-AC), JC (2 grants, Fondation ARC PJA 20141201975, Labex EpiGenMed ANR 10-LABX-0012), AT (2 grants, Gunma University GIAR Research Program for Omics-Based Medical Science, Labex MabImprove ANR 10-LABX-0053 starting grant), ET (1 grant, SIRIC Montpellier Cancer Grant INCa_Inserm_DGOS_12553).\nC_LIO_LINo conflict of interest\nC_LIO_LI5408 words, 1 table, and 4 figures\nC_LI\n\nStatement of translational relevanceBased on the presence or absence of an immune infiltrate, two groups of SDC were identified. These have the potential to provide a rationale for therapy and clinical trial enrolment. Two novel immune checkpoints that could be targeted were also identified; namely, CTLA-4/CD86 and TIM-3/galectin-9. Both showed the important contribution that macrophages and NK cells have in immunosuppression. Treatments that induce reprogramming or elimination of these cells could be considered. Moreover, the importance of the desmoplastic stroma was stressed. The stroma acts as a physical barrier against therapy suggesting that strategies developed against pancreatic tumors could inspire SDC treatments. For SDC devoid of immune infiltrate, components of the stroma including fibroblasts or hyaluronic acid could be targeted, e.g., in combination with drugs against immune checkpoints or mutated genes. Finally, evidence that Notch and TGF-{beta} signaling are prevalent in SDC was obtained. This translates into additional therapeutic options.

cancer biology↗