No abstract

Formation and homeostasis of the vascular system requires several coordinated cellular functions, but their precise interplay during development and their relative importance for vascular pathologies remain poorly understood. Here, we investigated the endothelial functions regulated by Cdc42 and their relevance during angiogenic sprouting and vascular morphogenesis in the postnatal mouse retina. We found that Cdc42 is required for endothelial tip cell selection, directed cell migration and filopodia formation, but dispensable for cell proliferation or apoptosis. Although the loss of Cdc42 seems generally compatible with apical-basal polarization and lumen formation in retinal blood vessels, it leads to defective endothelial axial polarization and to the formation of severe vascular malformations in capillaries and veins. Tracking of Cdc42-depleted endothelial cells in mosaic retinas suggests that these capillary-venous malformations arise as a consequence of defective cell migration, when endothelial cells that proliferate at normal rates are unable to re-distribute within the vascular network.

SIRT1 induces cell survival and has shown neuroprotection against amyloid and tau pathologies in Alzheimer's disease (AD). However, protective effects against memory loss or the enhancement of cognitive functions have not yet been proven. We aimed to investigate the benefits induced by SIRT1 overexpression in the hippocampus of the AD mouse model 3xTg-AD and in control non-transgenic mice. A lentiviral vector encoding mouse SIRT1 or GFP, selectively transducing neurons, was injected into the dorsal CA1 hippocampal area of 4-month-old mice. Six-month overexpression of SIRT1 fully preserved learning and memory in 10-month-old 3xTg-AD mice. Remarkably, SIRT1 also induced cognitive enhancement in healthy non-transgenic mice. Neuron cultures of 3xTg-AD mice, which show traits of AD-like pathology, and neuron cultures from non-transgenic mice were also transduced with lentiviral vectors to analyze beneficial SIRT1 mechanisms. We uncovered novel pathways of SIRT1 neuroprotection through enhancement of cell proteostatic mechanisms and activation of neurotrophic factors not previously reported such as GDNF, present in both AD-like and healthy neurons. Therefore, SIRT1 may increase neuron function and resilience against AD.

Puupehenone, a sesquiterpene produced by certain sponges, was selected in the course of a blind screening for new potential inhibitors of angiogenesis. In our study, we compare the potential anti-angiogenic activities of puupehenone and another 11 related compounds that were either natural products from marine origin or their synthetic derivatives. The effects of these compounds were determined with cell growth and differentiation assays on bovine aorta endothelial cells. Our results show that these compounds are weak inhibitors to cell growth and are not selective for endothelial cells. However, contrary to cell growth, the differentiation of endothelial cells into tubular structures was completely inhibited by 7 of these compounds at concentrations equal or lower than 3 M. Three of these compounds, isozonarol, 8-epipuupehedione and 8 epi-9,11-dihydropuupehedione, completely inhibited the in vivo angiogenesis in the CAM assay at doses equal or lower than 30 nmol/egg. Further characterisation showed that these 3 terpenes also inhibited endothelial cell production of urokinase and invasion. One compound (8-epipuupehedione) inhibited endothelial cell migration in a dose-dependent manner. The anti-angiogenic properties of the selected compounds, the simplicity of their structures and the feasibility of their synthesis make them attractive drugs for further evaluation in the treatment of angiogenesis-related pathologies.

Endothelial cells (ECs) adapt their metabolism to enable the growth of new blood vessels, but little is known how ECs regulate metabolism to adopt a quiescent state. Here, we show that the metabolite S-2-hydroxyglutarate (S-2HG) plays a crucial role in the regulation of endothelial quiescence. We find that S-2HG is produced in ECs after activation of the transcription factor forkhead box O1 (FOXO1), where it limits cell cycle progression, metabolic activity and vascular expansion. FOXO1 stimulates S-2HG production by inhibiting the mitochondrial enzyme 2-oxoglutarate dehydrogenase. This inhibition relies on branched-chain amino acid catabolites such as 3-methyl-2-oxovalerate, which increase in ECs with activated FOXO1. Treatment of ECs with 3-methyl-2-oxovalerate elicits S-2HG production and suppresses proliferation, causing vascular rarefaction in mice. Our findings identify a metabolic programme that promotes the acquisition of a quiescent endothelial state and highlight the role of metabolites as signalling molecules in the endothelium.