Methamphetamine induces AP-1 and NF-kB binding and transactivation in human brain endothelial cells

Cellular and molecular mechanisms of methamphetamine (METH)-induced neurotoxicity may involve alterations of cellular redox status and induction of inflammatory genes in endothelial cells. To study these hypotheses, molecular signaling pathways of METH-induced inflammatory responses via activation of redox-sensitive transcription factors were investigated in human brain microvascular endothelial cells (HBMEC). A dose-dependent depletion of total glutathione levels was detected in HBMEC exposed to METH. In addition, electrophoretic mobility shift assay (EMSA) showed significant increases in DNA binding activities of redox-responsive transcription factors, AP-1 and NF-κB, in HBMEC treated with METH. METH-mediated AP-1 or NF-κB activation was accompanied by induction of transactivation of AP-1 or NF-κB, as measured by dual luciferase assay using specific reporter plasmids. Because NF-κB and AP-1 are known to regulate expression of inflammatory genes, expression of the gene encoding for tumor necrosis factor-α (TNF-α) was also studied in METH-treated HBMEC. A dose-dependent overexpression of the TNF-α gene was observed in HBMEC treated with METH. The importance of AP-1 and NF-κB in METH-induced TNF-α gene was confirmed in functional promoter studies using constructs of the TNF-α promoter with mutated AP-1 or NF-κB sites. These results indicate that METH-induced disturbances in cellular redox status and activation of AP-1 and NF-κB can play critical roles in the signaling pathways leading to upregulation of inflammatory genes in human brain endothelial cells.