Abstract 11107: MT1-MMP Controls Akt-Dependent Fox01 Activation in TNF-alpha-Induced Signaling Pathways of Endothelial Cell Apoptosis and Haemostasis
Membrane type 1-matrix metalloproteinase (MT1-MMP), a membrane-anchored MMP, functions as a signaling molecule in addition to a proteolytic enzyme. Fox01 transcription factor, which is a substrate for Akt, regulates cellular metabolism, growth and differentiation in various cell types. Our hypothesis is that MT1-MMP regulates Akt-dependent Fox01 phosphorylation, which is critical in several signal transduction pathways in tumor necrosis factor (TNF)- α-induced signaling pathways of vascular responses including endothelial apoptosis and haemostasis. TNF-α (10 ng/mL) induced the decrease in Akt phosphorylation and the increase in Fox01 phosphorylation within 60 minutes in cultured human aortic endothelial cells (ECs). Immunohistochemistry demonstrated that MT1-MMP bound to Akt in TNF-α-stimulated ECs. To investigate the role of MT1-MMP for Akt/Fox01 signaling pathway in TNF-α-stimulated ECs, we used siRNA to knockdown MT1-MMP protein in ECs. Silencing of MT1-MMP by siRNA reversed the changed phsphorylation in Akt and Fox01 within 60 minutes in TNF-α-stimulated ECs, suggesting that MT1-MMP-mediated Akt/Fox01 phosphorylation is critical in modulation of TNF-α-induced signaling pathways. In the downstream events, TNF-α increased tissue factor (TF) expression and decreased thrombomoduline (TM) expression through Akt and Fox01 phosphorylation. Silencing of MT1-MMP by siRNA also reversed the changed expression of TF and TM induced by TNF-α. Furthermore, TNF-α induced the apoptosis of ECs through Akt-dependent Fox01 phosphorylation and silencing of MT1-MMP by siRNA inhibited TNF-α-induced apoptosis of ECs. In conclusions, we show new evidence that Akt-dependent Fox01 phosphorylation is a key modifier for TNF-α-induced signaling pathways in cooperation with MT1-MMP for modulation of endothelial cell apoptosis and haemostasis.
- © 2010 by American Heart Association, Inc.