Nerve Growth Factor Induces Endothelial Cell Invasion and Cord Formation by Promoting Matrix Metalloproteinase-2 Expression through the Phosphatidylinositol 3-Kinase/Akt Signaling Pathway and AP-2 Transcription Factor

Abstract

Nerve growth factor (NGF) is a well characterized neurotrophic agonist in the nervous system that triggers angiogenesis. In this study, we investigated the signaling mechanisms involved in NGF-induced angiogenesis. NGF stimulated endothelial cell invasion and cord formation on Matrigel in vitro but had marginal effect on proliferation and migration of these cells. NGF stimulated matrix metalloproteinase (MMP)-2 mRNA expression and protein secretion in human umbilical vein endothelial cells. Using synthetic and endogenous inhibitors of MMP-2 and MMP-2 small interfering RNA suppressed NGF-induced invasion and cord formation. We demonstrated that NGF-induced MMP-2 secretion, invasion, and cord formation are regulated via activation of the NGF receptor, TrkA, phosphatidylinositol 3-kinase (PI3K), and Akt using various pharmacological inhibitors. Specifically, NGF enhanced TrkA phosphorylation, PI3K activity, and Akt phosphorylation. Introduction of NGF-neutralizing antibodies, dominant-negative Akt, or wild-type PTEN effectively inhibited NGF-induced MMP-2 secretion and cord formation. Deletion and site-directed mutagenesis analysis of the MMP-2 promoter demonstrated that the AP-2-binding site is critical for NGF-induced MMP-2 promoter activity. NGF increased the DNA binding activity of AP-2, which was suppressed by inhibitors of TrkA and PI3K. Furthermore, transfection of AP-2 small interfering RNA effectively blocked NGFinduced MMP-2 secretion and cord formation. Finally, NGF promoted neovessel formation in Matrigel plugs in vivo, which was significantly inhibited by K252a and LY294002, but it failed to promote angiogenesis using MMP-2 knock-out mice. Our data collectively suggest that NGF stimulates endothelial cell invasion and cord formation by augmenting MMP-2 via the PI3K/Akt signaling pathway and AP-2 transcription factor, which may be responsible for triggering angiogenesis.

Nerve growth factor induces cord formation of mesenchymal stem cell by promoting proliferation and activating the PI3K/Akt signaling pathway

“…TrkA is a specific receptor of NGF and is involved in angiogenesis [22] . MyungJin Park et al demonstrated that TrkA activation induces endothelial cell invasion and cord formation [20] . However, our results showed TrkA mRNA were hardly detectable in MSCs, and NGF treatment had no significant effect on TrkA expression levels.…”

Regulation of epithelial cell polarity by PAR-3 depends on Girdin transcription and Girdin–Gαi3 signaling

“…Similar hollowing processes have also been reported to occur during endothelial cell lumen formation (Iruela-Arispe and Davis, 2009). PAR-3, aPKC, AP-2 family members and Girdin regulate lumen and tube formation by endothelial cells (Kitamura et al, 2008;Koh et al, 2008;Park et al, 2007;Zovein et al, 2010). Thus, it will be interesting to investigate whether a conserved molecular network comprising PAR-3, AP-2, Girdin and Gαi3 also regulates cell polarization during tube formation in endothelial tissues.…”

.ALPHA.-Chaconine Inhibits Angiogenesis in Vitro by Reducing Matrix Metalloproteinase-2

“…Numerous reports have demonstrated that MMP-2 expression is critically mediated by MAPK members 13,15) and PI3K/Akt pathway. 23,33,34) MAPK and PI3K/Akt pathways also play an important role in endothelial cell viability, migration, and tube formation by specific stimuli. [13][14][15]25,35,36) Therefore, we examined the effect of a-chaconine on the activities of MAPK and PI3K/Akt signaling pathways.…”