(I-353) Oligomeric Tau Alters Tight Junction Protein Expressions and Cerebral Endothelial Permeability: Role of RhoA/ROCK Signaling Pathway

Introduction:: Introduction: Tight junction (TJ) proteins in Cerebral Endothelial Cells (CECs) play an important role in maintaining the integrity of the blood-brain barrier (BBB). In Alzheimer’s disease (AD), BBB dysfunction has been associated with amyloid beta (Aβ) pathology, but how oligomeric Tau (oTau) impacts the BBB function has yet to be fully elucidated.

Materials and Methods:: Materials and Methods: Primary mouse CECs cultured in a transwell chamber was employed as our BBB model. Cells in the chamber were treated with oTau. To examine the involvement of the RhoA/ROCK pathway, cells were pre-treated with Fasudil, a RhoA/ROCK signaling inhibitor. Permeability of the CEC layer was measured by trans-endothelial transport of FITC-dextran and electrical resistances (TEER) assays. The expressions of TJ proteins (occludin, claudin-5, ZO-1) and p-p47phox in CECs were assayed by western blot analysis. Oxidatively modified proteins levels and proteasome activity were quantified by Protein Carbonyl Assay and Proteasome Activity Assay, respectively.

Results, Conclusions, and Discussions:: Results: Treating CECs with oTau significantly decreased TJ protein expressions and increased the permeability of the CEC layer. It also upregulated p-p47phox (subunit of NADPH oxidase) and increased oxidative damage of proteins, but decreased proteasome activity in CECs. These functional alterations of our BBB model induced by oTau were significantly suppressed by the pre-treatment with RhoA/ROCK signaling inhibitor, Fasudil.

Conclusion: Our findings suggest that the RhoA/ROCK pathway involved in oTau-induced disruption of BBB. Regulation of the RhoA/ROCK pathway can be a potential therapeutic strategy to maintain the BBB integrity in AD.

Acknowledgements (Optional): : This work was supported by National Institutes of Health R01AG044404 (JCL).

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