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KMID : 0606920130210020107
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Biomolecules & Therapeutics
2013 Volume.21 No. 2 p.107 ~ p.113
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Transcriptional Upregulation of Plasminogen Activator Inhibitor-1 in Rat Primary Astrocytes by a Proteasomal Inhibitor MG132
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Cho Kyu-Suk
Kwon Kyoung-Ja
Jeon Se-Jin
Joo So-Hyun
Kim Ki-Chan
Cheong Jae-Hoon
Bahn Geon-Ho
Kim Hahn-Young
Han Seol-Heui
Shin Chan-Young
Yang Sung-IL
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Abstract
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Plasminogen activator inhibitor-1 (PAI-1) is a member of serine protease inhibitor family, which regulates the activity of tissue plasminogen activator (tPA). In CNS, tPA/PAI-1 activity is involved in the regulation of a variety of cellular processes such as neuronal development, synaptic plasticity and cell survival. To gain a more insights into the regulatory mechanism modulating tPA/PAI-1 activity in brain, we investigated the effects of proteasome inhibitors on tPA/PAI-1 expression and activity in rat primary astrocytes, the major cell type expressing both tPA and PAI-1. We found that submicromolar concentration of MG132, a cell permeable peptide-aldehyde inhibitor of ubiquitin proteasome pathway selectively upregulates PAI-1 expression. Upregulation of PAI-1 mRNA as well as increased PAI-1 promoter reporter activity suggested that MG132 transcriptionally increased PAI-1 expression. The induction of PAI-1 downregulated tPA activity in rat primary astrocytes. Another proteasome inhibitor lactacystin similarly increased the expression of PAI-1 in rat primary astrocytes. MG132 activated MAPK pathways as well as PI3K/Akt pathways. Inhibitors of these signaling pathways reduced MG132-mediated upregulation of PAI-1 in varying degrees and most prominent effects were observed with SB203580, a p38 MAPK pathway inhibitor. The regulation of tPA/PAI-1 activity by proteasome inhibitor in rat primary astrocytes may underlie the observed CNS effects of MG132 such as neuroprotection.
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KEYWORD
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MG132, Lactacystin, p38, Plasminogen activator inhibitor-1, Tissue plasminogen activator
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