title: p38 MAP kinase mediates transforming-growth factor-β1-induced upregulation of matrix metalloproteinase-9 but not -2 in human brain pericytes.
abstract: Pericytes are vascular mural cells embedded within the basal lamina of blood micro-vessels. Within the neurovascular unit, pericytes play important roles in regulating neurovascular homeostasis by secreting soluble factors, such as matrix metalloproteinases (MMPs). However, little is known about the regulatory signaling pathways in brain pericytes. Here we show that transforming growth factor-β1 (TGF-β1) induces MMP-9 upregulation in pericytes via p38 mitogen-activated protein (MAP) kinase signaling. Cultured human brain vascular pericytes were used in this study. When the brain pericytes were treated with purified human TGF-β1 (0.1-10ng/mL for 24h), the levels of MMP-2 and MMP-9 in culture media were significantly increased in a concentration dependent manner as measured by gelatin zymography. WST assay confirmed that TGF-β1 did not affect cell survival of the brain pericytes. A TGF-β-receptor inhibitor SB431542 (0.5-5μM) decreased the TGF-β1-induced upregulation of MMP-2 and MMP-9. To assess the underlying intracellular mechanisms, we focused on p38 MAP kinase signaling, which is one of the major downstream kinases for TGF-β1. A well-validated p38 MAP kinase inhibitor SB203580 (0.5-5μM) cancelled the effect of TGF-β1 in upregulation of MMP-9 but not MMP-2. Western blotting confirmed that TGF-β1 treatment increased the level of p38 MAP kinase phosphorylation in pericytes, and again, the TGF-β-receptor inhibitor SB431542 (0.5-5μM) blocked the TGF-β1-induced phosphorylation of p38 MAP kinase. Both TGF-β1 and MMP-9 are major neurovascular mediators, and therefore, our current finding may suggest a novel mechanism for how pericytes regulate neurovascular homeostasis.
authors.affiliation: Department of Developmental Neuroscience, United Centers for Advanced Research and Translational Medicine, Tohoku University School of Medicine, Sendai, Japan; Neuroprotection Research Laboratory, Departments of Radiology and Neurology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Takahashi
authors.affiliation: Neuroprotection Research Laboratory, Departments of Radiology and Neurology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA.
authors.forename: Takakuni
authors.initials: T
authors.lastname: Maki
authors.affiliation: Neuroprotection Research Laboratory, Departments of Radiology and Neurology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA.
authors.forename: Anna C
authors.initials: AC
authors.lastname: Liang
authors.affiliation: Neuroprotection Research Laboratory, Departments of Radiology and Neurology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA.
authors.forename: Kanako
authors.initials: K
authors.lastname: Itoh
authors.affiliation: Neuroprotection Research Laboratory, Departments of Radiology and Neurology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA.
authors.forename: Josephine
authors.initials: J
authors.lastname: Lok
authors.affiliation: Department of Developmental Neuroscience, United Centers for Advanced Research and Translational Medicine, Tohoku University School of Medicine, Sendai, Japan.
authors.forename: Noriko
authors.initials: N
authors.lastname: Osumi
authors.affiliation: Neuroprotection Research Laboratory, Departments of Radiology and Neurology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA. Electronic address: karai@partners.org.
authors.forename: Ken
authors.initials: K
authors.lastname: Arai
mesh_terms: D001549:Benzamides / Q000494:pharmacology; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D002491:Central Nervous System Agents / Q000494:pharmacology; D004149:Dioxoles / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D020935:MAP Kinase Signaling System; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism*; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D020286:Pericytes / Q000187:drug effects / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D011725:Pyridines / Q000494:pharmacology; D018125:Receptors, Transforming Growth Factor beta / Q000037:antagonists & inhibitors / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: C459179:4-(5-benzo(1,3)dioxol-5-yl-4-pyridin-2-yl-1H-imidazol-2-yl)benzamide; D001549:Benzamides; D002491:Central Nervous System Agents; D004149:Dioxoles; D004791:Enzyme Inhibitors; D007093:Imidazoles; D011725:Pyridines; D018125:Receptors, Transforming Growth Factor beta; D011994:Recombinant Proteins; C508960:TGFB1 protein, human; D053773:Transforming Growth Factor beta1; D048051:p38 Mitogen-Activated Protein Kinases; C522361:MMP2 protein, human; D020778:Matrix Metalloproteinase 2; C579270:MMP9 protein, human; D020780:Matrix Metalloproteinase 9; C093642:SB 203580
keywords: MMP-9; Neurovascular unit; Pericyte; p38 MAP kinase