Rice Julie, Courter Donald L, Giachelli Cecilia M, Scatena Marta
Department of Pathology, University of Washington, Seattle 98195-1720, USA.
J Vasc Res. 2006;43(5):422-36. doi: 10.1159/000094884. Epub 2006 Aug 3.
The alphavbeta3 integrin interaction with the extracellular matrix (ECM) plays an essential role in inhibiting apoptosis in endothelial cells. We have recently shown that alphavbeta3 ligation on rat aortic endothelial cells (RAECs) specifically activates the transcription factor nuclear factor kappaB (NF-kappaB) and promotes cell survival. Inhibiting NF-kappaB nuclear translocation abolished the protective effect of alphavbeta3 ligands. Here, we report that ligation of alphavbeta3 by its ligand, osteopontin (OPN), induces the phosphorylation and activation of inhibitory kappa B kinase beta IKKbeta and promotes the specific degradation of inhibitory kappa Balpha (IkappaBalpha) in RAECs. Overexpression of a dominant negative (DN) IKKbeta protein prevents IkappaBalpha phosphorylation, NF-kappaB activation, and inhibits the protective effects of OPN. The NF-kappaB-inducing kinase (NIK) has been shown to be one of the upstream kinases involved in IKK activation. OPN-mediated NF-kappaB activity is increased upon NIK wild-type (WT) overexpression and blocked following NIK DN overexpression. In addition, NIK-/-mouse embryonic fibroblasts (MEFs) plated on OPN display reduced NF-kappaB activity and decreased IkappaBalpha phosphorylation compared to NIK+/+MEFs. Finally, functional inhibition of integrin beta3-dependent NF-kappaB signaling decreases OPN-induced IkappaBalpha, IKKbeta and NIK phosphorylation. These studies for the first time show that the alphavbeta3-NF-kappaB-dependent endothelial survival pathway is dependent on IkappaBalpha, IKKbeta, and NIK.
αvβ3整合素与细胞外基质（ECM）的相互作用在抑制内皮细胞凋亡中起重要作用。我们最近发现，大鼠主动脉内皮细胞（RAECs）上的αvβ3连接可特异性激活转录因子核因子κB（NF-κB）并促进细胞存活。抑制NF-κB核转位可消除αvβ3配体的保护作用。在此，我们报告其配体骨桥蛋白（OPN）连接αvβ3可诱导RAECs中抑制性κB激酶β（IKKβ）的磷酸化和激活，并促进抑制性κBα（IkappaBα）的特异性降解。显性负性（DN）IKKβ蛋白的过表达可阻止IkappaBα磷酸化、NF-κB激活，并抑制OPN的保护作用。NF-κB诱导激酶（NIK）已被证明是参与IKK激活的上游激酶之一。NIK野生型（WT）过表达时，OPN介导的NF-κB活性增加，而NIK DN过表达后则被阻断。此外，与NIK+/+小鼠胚胎成纤维细胞（MEFs）相比，接种在OPN上的NIK-/-小鼠胚胎成纤维细胞显示出NF-κB活性降低和IkappaBα磷酸化减少。最后，整合素β3依赖性NF-κB信号的功能抑制降低了OPN诱导的IkappaBα、IKKβ和NIK磷酸化。这些研究首次表明，αvβ3-NF-κB依赖性内皮细胞存活途径依赖于IkappaBα、IKKβ和NIK。
