Rush Stephen, Khan Gausal, Bamisaiye Ayoola, Bidwell Philip, Leaver H Anne, Rizzo Maria Teresa
Signal Transduction Laboratory, Methodist Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA.
Exp Cell Res. 2007 Jan 1;313(1):121-32. doi: 10.1016/j.yexcr.2006.09.018. Epub 2006 Sep 26.
Hepatocyte growth factor (HGF) influences several components of the angiogenic response, including endothelial cell migration. While recent studies indicate a crucial role of HGF in brain angiogenesis, the signaling pathways that regulate brain endothelial cell migration by HGF remain uncharacterized. Herein, we report that HGF stimulated human brain microvascular endothelial cell (HBMEC) migration in a dose- and time-dependent manner. Challenge of HBMECs with HGF activated the c-jun amino-terminal kinase (JNK), increased phosphorylation of the proline-rich tyrosine kinase 2 (Pyk-2) at Tyr(402) and activated c-Src. Inhibition of JNK by SP600125 or expression of a dominant negative JNK1 construct abrogated the migratory response of HBMECs to HGF. Treatment of HBMECs with the Src inhibitor PP2 markedly decreased HGF-stimulated JNK activation and migration to HGF. Moreover, expression of a mutant Pyk-2 construct prevented HGF-induced Pyk-2 phosphorylation at Tyr(402) and stimulation of HBMEC migration. Next, we examined activation of the extracellular signal regulated kinase (ERK) pathway. Stimulation of HBMECs by HGF led to rapid activation of ERK1/2, phosphorylation of Raf-1 at Ser(338) and Tyr(340/341) and MEK1/2 at Ser(222). Moreover, inhibition of ERK activation by UO126 and PD98059 markedly decreased HGF-stimulated HBMEC migration. HGF also activated AKT, while inhibition of AKT by LY294002 induced a modest decrease of HGF-induced HBMEC migration. These results highlight a model whereby JNK and ERK play a critical role in regulation of brain endothelial cell migration by HGF.
肝细胞生长因子（HGF）影响血管生成反应的多个组成部分，包括内皮细胞迁移。虽然最近的研究表明HGF在脑内血管生成中起关键作用，但HGF调节脑内皮细胞迁移的信号通路仍未明确。在此，我们报告HGF以剂量和时间依赖性方式刺激人脑血管内皮细胞（HBMEC）迁移。用HGF刺激HBMEC激活了c-Jun氨基末端激酶（JNK），增加了富含脯氨酸的酪氨酸激酶2（Pyk-2）在Tyr（402）位点的磷酸化，并激活了c-Src。用SP600125抑制JNK或表达显性负性JNK1构建体可消除HBMEC对HGF的迁移反应。用Src抑制剂PP2处理HBMEC可显著降低HGF刺激的JNK激活以及向HGF的迁移。此外，突变型Pyk-2构建体的表达可阻止HGF诱导的Pyk-2在Tyr（402）位点的磷酸化以及对HBMEC迁移的刺激。接下来，我们检测了细胞外信号调节激酶（ERK）通路的激活情况。HGF刺激HBMEC导致ERK1/2迅速激活，Raf-1在Ser（338）和Tyr（340/341）位点磷酸化，MEK1/2在Ser（222）位点磷酸化。此外，用UO126和PD98059抑制ERK激活可显著降低HGF刺激的HBMEC迁移。HGF还激活了AKT，而用LY294002抑制AKT可适度降低HGF诱导的HBMEC迁移。这些结果突出了一种模型，即JNK和ERK在HGF调节脑内皮细胞迁移中起关键作用。
