Dataset Information

Computational Model of Gab1/2-Dependent VEGFR2 Pathway to Akt Activation.

ABSTRACT: Vascular endothelial growth factor (VEGF) signal transduction is central to angiogenesis in development and in pathological conditions such as cancer, retinopathy and ischemic diseases. However, no detailed mass-action models of VEGF receptor signaling have been developed. We constructed and validated the first computational model of VEGFR2 trafficking and signaling, to study the opposing roles of Gab1 and Gab2 in regulation of Akt phosphorylation in VEGF-stimulated endothelial cells. Trafficking parameters were optimized against 5 previously published in vitro experiments, and the model was validated against six independent published datasets. The model showed agreement at several key nodes, involving scaffolding proteins Gab1, Gab2 and their complexes with Shp2. VEGFR2 recruitment of Gab1 is greater in magnitude, slower, and more sustained than that of Gab2. As Gab2 binds VEGFR2 complexes more transiently than Gab1, VEGFR2 complexes can recycle and continue to participate in other signaling pathways. Correspondingly, the simulation results show a log-linear relationship between a decrease in Akt phosphorylation and Gab1 knockdown while a linear relationship was observed between an increase in Akt phosphorylation and Gab2 knockdown. Global sensitivity analysis demonstrated the importance of initial-concentration ratios of antagonistic molecular species (Gab1/Gab2 and PI3K/Shp2) in determining Akt phosphorylation profiles. It also showed that kinetic parameters responsible for transient Gab2 binding affect the system at specific nodes. This model can be expanded to study multiple signaling contexts and receptor crosstalk and can form a basis for investigation of therapeutic approaches, such as tyrosine kinase inhibitors (TKIs), overexpression of key signaling proteins or knockdown experiments.

SUBMITTER: Tan WH

PROVIDER: S-EPMC3689841 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Computational Model of Gab1/2-Dependent VEGFR2 Pathway to Akt Activation.

Tan Wan Hua WH Popel Aleksander S AS Mac Gabhann Feilim F

PloS one 20130621 6

Vascular endothelial growth factor (VEGF) signal transduction is central to angiogenesis in development and in pathological conditions such as cancer, retinopathy and ischemic diseases. However, no detailed mass-action models of VEGF receptor signaling have been developed. We constructed and validated the first computational model of VEGFR2 trafficking and signaling, to study the opposing roles of Gab1 and Gab2 in regulation of Akt phosphorylation in VEGF-stimulated endothelial cells. Traffickin ...[more]

PMID: 23805312

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Project description:BackgroundWe have revealed that neuropilin-1 (NRP-1) promoted hepatic stellate cell activation and liver fibrosis through its profibrogenic signalling pathways. However, the role of NRP-1 in angiogenesis in hepatic sinusoidal endothelial cells (HSECs) during liver cirrhosis remains unclear.MethodsThe correlation between NRP-1 expression and angiogenesis was evaluated in both human and murine cirrhotic liver tissues by immunohistochemical staining, quantitative real-time PCR, and western blotting. In addition, the role and mechanism of NRP-1 in regulating VEGFR2-dependent angiogenesis was identified in endothelial cells (ECs) in vitro. Moreover, liver histocultures were used to test the therapeutic effect of NRP-1 blocking in liver fibrosis.FindingsHigher expression of NRP-1 in HSECs was detected, which was positively correlated with angiogenesis in liver cirrhosis. In vitro, NRP-1 knockdown suppressed the expression and activation of VEGFR2, accompanied by reduced ability of the vascular tube formation and the migration of ECs. Conversely, NRP-1 overexpression upregulated VEGFR2, promoted tube formation, and the migration of ECs. Mechanistically, NRP-1 modulated the expression of VEGFR2 by regulating FAK and its kinase activity. Furthermore, NRP-1 promoted VEGFR2-dependent angiogenesis via the PI3K/Akt pathway in HSECs. Blocking NRP-1 function reduced intrahepatic angiogenesis and fibrosis-associated factors in the in vitro liver histocultures.InterpretationNRP-1 promotes angiogenesis by upregulating the expression and activation of VEGFR2 through the PI3K/Akt signalling pathway in liver cirrhosis. This study highlights the possibility of therapeutically targeting NRP-1 for the treatment of cirrhosis. FUND: National Natural Science Foundation of China (No. 81570551; 81770607; 81600469; 81401868), Key Research project of Shandong Province (No. 2016GSF201008; 2017GSF218053), Natural Science Foundation of Shandong Province (No. ZR2017MH102), National Science and Technology Major Project of China (No. 2018ZX10302206-001-006).

Project description:Combination of antiangiogenesis and immunotherapy may be an effective strategy for treatment of solid tumors. Our previous work reported that activation of CD137 signaling promotes intraplaque angiogenesis. A number of studies have demonstrated that vascular endothelial growth factor receptor 2 (VEGFR2) is a key target for angiogenesis. However, it is unknown whether CD137-mediated angiogenesis is related to VEGFR2. In this study, we investigated the effect of CD137 on the VEGFR2 expression and explored the underlying mechanisms of CD137-mediated angiogenesis. Knock-out of CD137 in ApoE-/- mice significantly decreased neovessel density in atherosclerotic plaques. CD137 silencing or inhibition attenuated endothelial cell (ECs) proliferation, migration, and tube formation. We found activation of CD137 signaling for increased VEGFR2 transcription and translation steadily. Moreover, CD137 signaling activated phosphorylated VEGFR2 (Tyr1175) and the downstream Akt/eNOS pathway, whereas neutralizing CD137 signaling weakened the activation of VEGFR2 and the downstream Akt/eNOS pathway. The aortic ring assay further demonstrated that CD137 signaling promoted ECc sprouting. Inhibition of VEGFR2 by siRNA or XL184 (cabozantinib) and inhibition of downstream signaling by LY294002 (inhibits AKT activation) and L-NAME (eNOS inhibitor) remarkably abolished proangiogenic effects of CD137 signaling both in vitro and ex vivo. In addition, the condition medium from CD137-activated ECs and vascular endothelial growth factor A (VEGFA) had similar effects on ECs that expressed high VEGFR2. Additionally, activating CD137 signaling promoted endothelial secretion of VEGFA, while blocking CD137 signaling attenuated VEGFA secretion. In conclusion, activation of CD137 signaling promoted sprouting angiogenesis by increased VEGFA secretion and the VEGFR2/Akt/eNOS pathway. These findings provide a basis for stabilizing intraplaque angiogenesis through VEGFR2 intervatioin, as well as cancer treatment via combination of CD137 agonists and specific VEGFR2 inhibitors.

Dataset Information

Computational Model of Gab1/2-Dependent VEGFR2 Pathway to Akt Activation.

Publications

Computational Model of Gab1/2-Dependent VEGFR2 Pathway to Akt Activation.

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