Department of Pharmacology, College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, San 56-1, Shillim-Dong, Kwanak-Gu, Seoul, 151-742, Korea.
Neurochem Res. 2010 Jul;35(7):976-85. doi: 10.1007/s11064-010-0141-3. Epub 2010 Feb 23.
In response to brain injury, microglia migrate and accumulate in the affected sites, which is an important step in the regulation of inflammation and neuronal degeneration/regeneration. In this study, we investigated the effect of urokinase-type plasminogen activator (uPA) on the BV-2 microglial cell migration. At resting state, BV-2 microglial cells secreted uPA and the release of uPA was increased by ATP, a chemoattractant released from injured neuron. The migration of BV-2 cell was significantly induced by uPA and inhibited by uPA inhibitors. In this condition, uPA increased the activity of matrix metalloproteinase (MMP-9) and the inhibition of MMP activity with pharmacological inhibitors against either uPA (amiloride) or MMP (phenanthrolene and SB-3CT) effectively prevented BV2 cell migration. Interestingly, the level of MMP-9 protein and mRNA in the cell were not changed by uPA. These results suggest that the increase of MMP-9 activity by uPA is regulated at the post-translational level, possibly via increased activation of the enzyme. Unlike the uPA inhibitor, plasmin inhibitor PAI-1 only partially inhibited uPA-induced cell migration and MMP-9 activation. The incubation of recombinant MMP-9 with uPA resulted in the activation of MMP-9. These results suggest that uPA plays a critical role in BV-2 microglial cell migration by activating pro-MMP-9, in part by its direct action on MMP-9 and also in part by the activation of plasminogen/plasmin cascade.
针对脑损伤，小胶质细胞迁移并聚集在受影响的部位，这是调节炎症和神经元变性/再生的重要步骤。在这项研究中，我们研究了尿激酶型纤溶酶原激活物（uPA）对 BV-2 小胶质细胞迁移的影响。在静止状态下，BV-2 小胶质细胞分泌 uPA，ATP（损伤神经元释放的趋化因子）的释放会增加 uPA 的释放。uPA 显著诱导 BV-2 细胞迁移，并被 uPA 抑制剂抑制。在这种情况下，uPA 增加了基质金属蛋白酶（MMP-9）的活性，而用药理学抑制剂抑制 MMP 活性（amiloride 针对 uPA，phenanthrolene 和 SB-3CT 针对 MMP）可有效阻止 BV2 细胞迁移。有趣的是，uPA 并未改变细胞中 MMP-9 蛋白和 mRNA 的水平。这些结果表明，uPA 可通过增加酶的激活来调节 MMP-9 活性的增加，这可能发生在翻译后水平。与 uPA 抑制剂不同，纤溶酶抑制剂 PAI-1 仅部分抑制 uPA 诱导的细胞迁移和 MMP-9 激活。uPA 与重组 MMP-9 孵育会导致 MMP-9 激活。这些结果表明，uPA 通过激活 pro-MMP-9 在 BV-2 小胶质细胞迁移中起关键作用，部分是通过其对 MMP-9 的直接作用，部分是通过纤溶酶原/纤溶酶级联的激活。
