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Cx40 Suppresses Sprouting Angiogenesis In Vitro

ABSTRACT: Blood vessels are highly organized and form during development through a series of complex processes that include vasculogenesis, sprouting angiogenesis, and vessel remodeling. Several gap junction proteins (termed connexins, Cx) – including Cx40 (GJA5) – are expressed in vascular endothelium early during vessel development and are critical for establishment of a healthy vasculature. However, Cx40’s specific role in regulating vessel growth remains uncertain: while previous studies have shown that developmental and cancer-associated neovascularization is reduced in Cx40-knockout mice, Cx40 knockout in zebrafish embryos enhances intersegmental vessel growth. Thus, in the current study, our aim was to identify Cx40’s specific role in sprouting angiogenesis. First, we used a vessel-on-a-chip microphysiological model to confirm Cx40’s overall necessity for microvessel network development. Next, we used the fibrin gel bead assay – a three-dimensional in vitro model of sprouting angiogenesis – to assess Cx40’s necessity for this process. We found that Cx40 knockdown in endothelial cells drives more aggressive sprouting angiogenesis in association with increased endothelial cell proliferation. By contrast, using Electrical Cell-substrate Impedance Sensing (ECIS) we observed no effect of Cx40 knockdown on endothelial cell migration. Lastly, we found that Cx37 (GJA4) is reduced in Cx40- deficient endothelial cells, and that targeted silencing of Cx37 alone produces a more aggressive, hyper-sprouting phenotype compared to control or Cx40 knockdown endothelial cells. Taken together, our data argue that Cx40 plays multiple roles during vessel growth, including to specifically limit sprouting angiogenesis, and that this may occur (at least in part) through regulation of endothelial Cx37 levels.

ORGANISM(S): Homo sapiens

PROVIDER: GSE243404 | GEO | 2023/12/14

REPOSITORIES: GEO

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Project description:Branching from conduits is a defining feature of the gas delivery systems of invertebrates (tracheae built from epithelial cells) and vertebrates (vasculature lined by endothelial cells). Here, we show that the vertebrate transcriptional repressor Tel plays an evolutionarily conserved role in angiogenesis: it is indispensable for sprouting of primary human endothelial cells and for the normal development of the Danio rerio embryo blood circulatory system. Tel controls endothelial sprouting via binding to the generic co-repressor C-terminal binding protein (CtBP). In endothelial cells, the Tel:CtBP complex temporally restricts a VEGF-mediated pulse of dll4 expression and consequently integrates VEGFR intracellular signaling and intercellular Notch-Dll4 signaling. It further refines branching by regulating expression of other factors that constrain angiogenesis such as sprouty family members and ve-cadherin. Thus, the Tel:CtBP complex moderates the balance between positive and antagonistic angiogenesis cues and thereby conditions endothelial cells for angiogenesis. Since the activity of CtBP is attuned to intracellular NADH levels, our results raise the possibility that Tel-mediated sprouting could be sensitized to the metabolic status of the tissue. Tel control of branching appears to be evolutionarily conserved since Yan, the invertebrate orthologue of Tel, is similarly required for branching morphogenesis of the invertebrate tracheae. Collectively, our work suggests that Tel is a central regulator of angiogenesis and highlights Tel and its associated networks as potential targets for the development of therapeutic strategies to inhibit pathological angiogenesis. 2 independent screens were performed testing effects of knockdown of Tel or CtBP (screen 1) or effects of VEGF-A (screen 2) on Human Umbilical Vein Endothelial Cells (HUVECs). For screen 1 we tested 3 different conditions. We established stable HUVEC cell lines which were either infected with control lentivirus (Mock), or lentivirus expressing short hairpin RNA constructs for the specific knockdown of Tel(Teli) or CtBP2 (CtBP2i). Expression in the Teli and CtBP2i cell lines was compared to expression in the Mock cell line for screen 1. For screen 2 we tested 2 conditions. We exposed HUVECs to VEGF (50ng/mL) for 30 minutes (samplename: VEGF30) and compared the transcriptome of these cells to untreated HUVECs (VEGF0). For each condition 2 independent repeats were analyzed and expression of genes was averaged for each repeat. HUVECs were grown under standard conditions (37degrees Celsius, 5% CO2) in EGM2 medium (Lonza).

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Cx40 Suppresses Sprouting Angiogenesis In Vitro

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