Implications of Caveolae in Tat Signaling and Integrity of Brain Endothelium

CNS complications of HIV infection remain a serious risk in HIV-1 infection despite significant advances in highly acbve antiretrovlral therapy. Our research is based on a general hypothesis that specific HIV proteins. such as Tal. contribute to the dysfunction of brain microYascular endothelial cells (BMEC) and !he disrUption of !he bIood-brain barrier (BBB). facilitabng virus enlly into the brain. The present granl application is designed to study the signaNngmechanisms that can be responsible for these effects. Our recent preliminary data Indicate that eKposure of endothelial cells to Tal results In immediate localiza~on of Tat to caveolae, the subset of lipid raflscharacterized by the presence of proteins termed caveolins. The importance of this observation Is related to the fact that a variety 0fcelisurfacereceptQl'S and signaling pathways activated by Tat are also localized in these membrane domains. In addilion.wedemonstrntelhatsilencingofcaveolin-t protein can protect against Tat--mediated CNS compliCBBB, Mechanistically, we propose that Tat-induced alterations of the Ras and Rho signaling pathways result in disturbances in tight J'unction protein expression, leading to increased transendothelial passage of inflammatory celis and HIVentry into the brain. Wealso prQPosethalsta1inscanregulateGaveolae-associatedsignalingand protect against Tatmediated vascular toxicity This project is interdisciplinary and combines molecular and vascular biology with proclinical approaches. It is based on the newly developed co-cultures of human brain microvascular endothelial cells (HBMEC) with genetically altered human astrocyte cell lines that produce Tat (SVGA-Tat cells). This proposal is the first attempt to study the role offu~clional caveolae in the regulation of the BBB in relationship to HIV-1 infection. Data arising from this prop05al will be critical fora better understanding of the developm entofthe BBB dysfunction in neuroAlDS. The long term goals of this proposal are to determine therapeutic strategies to prevent neurological GOmplications of HIV infection.