Zinc-Triggered Induction of Tissue Plasminogen Activator and Plasminogen in Endothelial Cells and Pericytes

Cerebral amyloid angiopathy (CAA) is common in patients with Alzheimer's disease (AD) and may contribute to cerebral hemorrhage. We previously demonstrated that tissue plasminogen activator (tPA) and plasminogen (PLG) accumulated at the periphery of compact amyloid-cored plaques and in the walls of CAA-containing blood vessels in the brains of Tg2576 mice, a widely used AD mouse model. We had also observed that zinc-triggered tPA and PLG induction were observed in mouse cortical cultures. Because zinc also accumulates in amyloid plaques and blood vessel walls in AD brains, we examined whether zinc increases mRNA and protein levels of tPA and PLG in brain endothelial cells and pericytes. Four hours after the exposure of brain endothelial cells (bEnd.3) to 40 microM zinc, the mRNA and protein expressions of tPA and its substrate PLG were significantly increased. In the case of brain pericyte cultures, increases in tPA and PLG expression were also detected 2 hr after treatment. However, amyloid-beta (Abeta)1-42 oligomers did not augment tPA and PLG expression in bEnd.3 cells and pericytes, suggesting that zinc but not Abeta induces tPA and PLG accumulation in CAA found in the AD brain.

Protective Effect of HSP90 on Neuronal Cell Death-induced by beta-Amyloid Peptide / 체질인류학회지

In the present study, we determined the protective mechanism of HSP90 against neuronal cell death induced by Abeta. For the evaluation of protective role of HSP90, we used human neuroblastoma SK-N-SH cell lines, examined AlamarBlue assay, Western blot analysis and immunofluorescence assay. Incubation of SK-N-SH cells with Abeta significantly induced neuronal cell death. However, HSP90 induced by mild heat shock could attenuate neuronal apoptosis in Abeta treated condition. To identify the role of HSP90, we determined localization of HSP90 in SK-N-SH cells. Interestingly, HSP90 was increased and localized in mitochondria as treatment of mild heat shock. Also, treatment or increase of HSP90 largely elevated level of Bcl-2 expression, whereas inhibition of HSP90 with HSP90 antisense oligonucleotide significantly decreased Bcl-2 expression. In contrast to Bcl-2, Bax expression was regulated independently by HSP90. Moreover, increase of HSP90 could attenuate collapse of mitochondrial membrane potential induced by Abeta. However, HSP90 antisense oligonucleotide largely increase breakdown of mitochondrial membrane potential induced by Abeta. These data suggest that HSP90 as chaperone protein significantly attenuates neuronal damage and protects neuroanl cells from neurotoxin such as Abeta.