Lu Yunbiao, Wahl Larry M
Immunopathology Sction, National Institute of Dental and Craniofacial Research, National Institute of Health, Bethesda, MD 20892-4352, USA.
J Leukoc Biol. 2005 Jul;78(1):259-65. doi: 10.1189/jlb.0904498. Epub 2005 Mar 30.
Matrix metalloproteinase-9 (MMP-9) is considered to be an important component in the progression of inflammation. Monocytes/macrophages are prominent at inflammation sites, and activation of these cells by stimulants, such as lipopolysaccharide (LPS) or tumor necrosis factor alpha and granulocyte macrophage-colony stimulating factor, leads to the production of significant amounts of MMP-9. Here, we show that LPS stimulation of monocytes results in MMP-9 production through a phosphatidylinositol-3 kinase (PI-3K)/Akt/inhibitor of kappaB (IkappaB) kinase-alpha (IKKalpha)/nuclear factor (NF)-kappaB pathway. This new role for Akt in signaling leading to MMP-9 production was demonstrated by inhibitor and immunoprecipitation studies. LY294002 or wortmannin, inhibitors of PI-3K, suppressed LPS-induced Akt activity and MMP-9 production. Evidence for the participation of Akt in monocyte MMP-9 synthesis was demonstrated by the inhibition of MMP-9 by SH-5, a specific inhibitor of Akt. The mechanism by which Akt regulates MMP-9 is through the activation of NF-kappaB, as shown by coimmunoprecipitation of the phosphorylated form of IKKalpha and Akt as well as the SH-5 suppression of the dissociation of IkappaB from NF-kappaB and the activation of NF-kappaB p65. The role of NF-kappaB in regulation of MMP-9 was demonstrated further by the inhibition of MMP-9 production by proteasome inhibitors, lactacystin and MG-132, which prevented the ubiquitination and dissociation of IkappaB from NF-kappaB. This is the first demonstration that Akt is involved in the signaling pathway leading to the production of monocyte MMP-9 and provides an additional approach in the regulation of this enzyme in human primary monocytes.
基质金属蛋白酶-9（MMP-9）被认为是炎症进展中的一个重要成分。单核细胞/巨噬细胞在炎症部位很突出，这些细胞被脂多糖（LPS）、肿瘤坏死因子α或粒细胞巨噬细胞集落刺激因子等刺激物激活后，会导致大量MMP-9的产生。在此，我们表明LPS刺激单核细胞通过磷脂酰肌醇-3激酶（PI-3K）/Akt/κB抑制因子激酶α（IKKα）/核因子（NF）-κB途径导致MMP-9产生。抑制剂和免疫沉淀研究证明了Akt在导致MMP-9产生的信号传导中的这一新作用。PI-3K抑制剂LY294002或渥曼青霉素可抑制LPS诱导的Akt活性和MMP-9产生。Akt特异性抑制剂SH-5对MMP-9的抑制作用证明了Akt参与单核细胞MMP-9合成。Akt调节MMP-9的机制是通过激活NF-κB，这表现为IKKα磷酸化形式与Akt的共免疫沉淀，以及SH-5对IkappaB从NF-κB解离和NF-κB p65激活的抑制。蛋白酶体抑制剂乳胞素和MG-132对MMP-9产生的抑制作用进一步证明了NF-κB在调节MMP-9中的作用，它们可防止IkappaB从NF-κB的泛素化和解离。这是首次证明Akt参与导致单核细胞MMP-9产生的信号通路，并为人类原代单核细胞中该酶的调节提供了另一种方法。
