title: Microglial low-density lipoprotein receptor-related protein 1 mediates the effect of tissue-type plasminogen activator on matrix metalloproteinase-9 activity in the ischemic brain.
abstract: Studies in animal models of cerebral ischemia indicate that besides its thrombolytic effect, treatment with tissue-type plasminogen activator (tPA) also induces an increase in matrix metalloproteinase-9 (MMP-9) activity in the ischemic tissue associated with the development of cerebral edema. Earlier, we had shown that the low-density lipoprotein receptor-related protein 1 (LRP1) is a substrate for tPA in the brain. In this study, we investigated the effect of the interaction between tPA and microglial LRP1 on MMP-9 activity after middle cerebral artery occlusion (MCAO). We found that exposure to oxygen-glucose deprivation (OGD) conditions increases MMP-9 activity in wild-type (Wt) and plasminogen-deficient (Plg(-/-)) microglia, but not in tPA (tPA(-/-)) or LRP1-deficient (macLRP-) cells. Treatment with tPA increases MMP-9 expression in tPA(-/-) but not in macLRP- microglia. Middle cerebral artery occlusion increases MMP-9 expression and activity in Wt but not in tPA(-/-) or macLRP- mice, and treatment with tPA increases MMP-9 activity in tPA(-/-) mice but not in macLRP- animals. Finally, MCAO-induced ischemic edema and degradation of the interendothelial right junction protein claudin-5 were significantly attenuated in tPA(-/-) and macLRP- mice. The results of our study indicate that the interaction between tPA and microglial LRP1 increases MMP-9 expression and activity resulting in the degradation of claudin-5 and development of cerebral edema.
authors: Department of Neurology and Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
authors: Chen
authors: C
authors: Zhang
authors: Jie
authors: J
authors: An
authors: Woldeab B
authors: WB
authors: Haile
authors: Ramiro
authors: R
authors: Echeverry
authors: Dudley K
authors: DK
authors: Strickland
authors: Manuel
authors: M
authors: Yepes
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism / Q000503:physiopathology; D002545:Brain Ischemia / Q000378:metabolism*; D002478:Cells, Cultured; D005786:Gene Expression Regulation; D026503:Low Density Lipoprotein Receptor-Related Protein-1 / Q000378:metabolism*; D020780:Matrix Metalloproteinase 9 / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D017628:Microglia / Q000166:cytology / Q000378:metabolism*; D010959:Tissue Plasminogen Activator / Q000235:genetics / Q000378:metabolism*
chemical_list: D026503:Low Density Lipoprotein Receptor-Related Protein-1; D010959:Tissue Plasminogen Activator; D020780:Matrix Metalloproteinase 9