Urokinase-type plasminogen activator induces BV-2 microglial cell migration through activation of matrix metalloproteinase-9.
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.
Shin
Sun Mi
SM
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.
Cho
Kyu Suk
KS
Choi
Min Sik
MS
Lee
Sung Hoon
SH
Han
Seol-Heui
SH
Kang
Young-Sun
YS
Kim
Hee Jin
HJ
Cheong
Jae Hoon
JH
Shin
Chan Young
CY
Ko
Kwang Ho
KH
D000818:Animals; D002460:Cell Line; D002465:Cell Movement; D004789:Enzyme Activation; D005341:Fibrinolysin / Q000037:antagonists & inhibitors / Q000502:physiology; D020780:Matrix Metalloproteinase 9 / Q000235:genetics / Q000378:metabolism*; D061965:Matrix Metalloproteinase Inhibitors; D051379:Mice; D017628:Microglia / Q000502:physiology*; D010958:Plasminogen / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D014568:Urokinase-Type Plasminogen Activator / Q000037:antagonists & inhibitors / Q000502:physiology*
D061965:Matrix Metalloproteinase Inhibitors; D012333:RNA, Messenger; D010958:Plasminogen; D005341:Fibrinolysin; D014568:Urokinase-Type Plasminogen Activator; D020780:Matrix Metalloproteinase 9; C501830:Mmp9 protein, mouse