Project description:The Aster-C protein (encoded by the Gramd1c gene) is an endoplasmic reticulum (ER) resident protein that has been reported to transport cholesterol from the plasma membrane to the ER . Although there is a clear role for the closely-related Aster-B protein in cholesterol transport and downstream esterification in the adrenal gland, the specific role for Aster-C in tissue cholesterol homeostasis is not well understood. Here, we have examined whole body cholesterol balance in mice globally lacking Aster-C under low or high dietary cholesterol conditions.transport and metabolism under divergent dietary cholesterol conditions. These results strongly suggest that Aster-C alone is not sufficient to control whole body cholesterol balance, but can modestly impact circulating cortisol and bile acid levels when dietary cholesterol is limited.
Project description:Regulation of endothelial nutrient transport is poorly understood. Vascular endothelial growth factor (VEGF)-B signaling in endothelial cells promotes uptake and transcytosis of fatty acids (FA) from the bloodstream to the underlying tissue, advancing pathological lipid accumulation and lipotoxicity in diabetic complications. Here we demonstrate a VEGF-B dependent obstruction of endothelial glucose transport attributed to plasma membrane lipid alterations affecting glucose transporter 1 function, which was independent of FA uptake. Specifically, VEGF-B signaling impaired recycling of low-density lipoprotein receptor to the plasma membrane, leading to reduced cholesterol uptake and membrane cholesterol loading, decreasing endothelial glucose uptake capacity. Inhibiting VEGF-B in vivo was accordingly linked to reconstitution of membrane cholesterol and induction of glucose uptake, of particular relevance for conditions inferring insulin resistance and diabetic complications. In summary, our study reveals a novel mechanism of action for VEGF-B in endothelial nutrient uptake and highlights the impact of membrane cholesterol for the regulation of endothelial glucose transport.
Project description:Regulation of endothelial nutrient transport is poorly understood. Vascular endothelial growth factor (VEGF)-B signaling in endothelial cells promotes uptake and transcytosis of fatty acids (FA) from the bloodstream to the underlying tissue, advancing pathological lipid accumulation and lipotoxicity in diabetic complications. Here we demonstrate a VEGF-B dependent obstruction of endothelial glucose transport attributed to plasma membrane lipid alterations affecting glucose transporter 1 function, which was independent of FA uptake. Specifically, VEGF-B signaling impaired recycling of low-density lipoprotein receptor to the plasma membrane, leading to reduced cholesterol uptake and membrane cholesterol loading, decreasing endothelial glucose uptake capacity. Inhibiting VEGF-B in vivo was accordingly linked to reconstitution of membrane cholesterol and induction of glucose uptake, of particular relevance for conditions inferring insulin resistance and diabetic complications. In summary, our study reveals a novel mechanism of action for VEGF-B in endothelial nutrient uptake and highlights the impact of membrane cholesterol for the regulation of endothelial glucose transport.
Project description:A small dose of the anti-HIV drug efavirenz (EFV) was previously discovered to activate CYP46A1, a cholesterol-eliminating enzyme in the brain, and mitigate some of the manifestation of Alzheimer’s disease in 5XFAD mice. Herein, we investigated the retina of these animals, which were found to have genetically determined retinal vascular lesions associated with deposits within the retinal pigment epithelium and subretinal space. We established that EFV treatment activated CYP46A1 in the retina, enhanced retinal cholesterol turnover, and diminished the lesion frequency >5-fold. In addition, the treatment mitigated fluorescein leakage from the aberrant blood vessels, deposit size, activation of retinal macrophages/microglia, and focal accumulations of amyloid b plaques, unesterified cholesterol, and Oil Red O-positive lipids. Studies of retinal transcriptomics and proteomics identified biological processes enriched with differentially expressed genes and proteins. We discuss the mechanisms of the beneficial EFV effects on the retinal phenotype of 5XFAD mice. As EFV is an FDA-approved drug, and we already tested the safety of small-dose EFV in patients with Alzheimer’s disease, our data support further clinical investigation of this drug in subjects with retinal vascular lesions or neovascular age-related macular degeneration.
Project description:We have previously reported that the dengue virus (DENV) type 3 P12/08 strain caused a lethal systemic infection, severe vascular leakage at terminal stage in IFN-α/β and γ receptors knockout mice (IFN-α/β/γRKO mice), and blockade of TNF-α signaling drastically protected mice. However, the detailed pathological mechanism remains unknown. Therefore, we performed transcriptome analysis of liver and intestinal specimens, which showed most clearly exhibited vascular leakage, chronologically collected from infected- IFN-α/β/γRKO mice with/without anti-TNF-α Ab treatment.
Project description:The goal was to investigate whether the induction of gene expression by vascular endothelial growth factor (VEGF) in endothelial cells depends on endosomal GTPases Rab5A or Rab5C.
Project description:Angiogenesis is an essential process in human physiology and disease pathology. Particularly, in ischemic disease condition, the proper induction of angiogenesis without vascular leakage will be crucial for its effective therapy. Ginsenosides, triterpenoid saponins from a well-known medicinal plant ginseng, have been considered as a strong candidate for modulating angiogenesis. However, the biologic activity of individual gensenoside compounds and their target pathway have not been elucidated systematically. To find the candidates of vascular-related therapeutic agents, we evaluated in vitro angiogenic efficacy of 10 ginsenosides using tube formation assay with human umbilical vein endothelial cells (HUVECs). Among them, F1 and Rh1 showed strong in vitro angiogenic properties including EC tube formation, proliferation, and migration similar to vascular endothelial growth factor (VEGF). However, RNA transcriptome analysis showed that F1 and Rh1 differentially regulate gene expressions in HUVECs compared to VEGF. Not only that, F1 and Rh1 significantly inhibited vascular endothelial growth factor (VEGF)-induced vascular leakage both in vitro and in vivo. From RNA transcriptome analysis, we identified that nuclear receptor subfamily 4 group A member 1 (NR4A1) is regulated by F1 and Rh1 for suppression of VEGF-induced vascular leakage. By suppressing the expression and transcriptional activity of NR4A1, F1 and Rh1 could stabilize the expression and localization of junctional vascular endothelial (VE)-cadherin. These findings demonstrate that F1 and Rh1 could be potential compounds in the development of vascular pharmaceuticals.
Project description:Levels of membrane-associated cholesterol were shown to be increased in the brain of individuals with sporadic AlzheimerM-bM-^@M-^Ys disease (AD) and correlated with the severity of the disease. We previously found that heavy membrane cholesterol burden promotes amyloid precursor protein (APP) endocytosis and processing, leading to increased amyloid-M-oM-^AM-"M-oM-^@M- M-oM-^@M-(AM-oM-^AM-") secretion. We hypothesized that such an increase of cholesterol could trigger sporadic AD. We thus acutely loaded the plasma membrane of neurons in culture with cholesterol to reach the 30 % increase observed in AD brains. We showed by multiplex electro-chemiluminescence immuno-assay that transient membrane cholesterol loading produced a significant increase of AM-oM-^AM-"42 secretion. We also found that early endosomes were enlarged and more prone to aggregation using confocal and electron microscopy and that APP vesicular transport in neuronal processes was slowed down using fluorescence live-imaging. In addition, treatment of neurons with cholesterol induced changes in gene expression profile that are reminiscent of early AD. This model of membrane cholesterol increase in cultured neurons reproduces most of early AD changes and could thus be relevant for deciphering early mechanisms and design new targets for sporadic AD. In this study, we loaded the plasma membrane of neurons with 30% more cholesterol and observed the effects on gene expression. We compared gene expression of primary hippocampal neurons treated or not with cholesterol using 4 independant replicates in each group.