Intact lipid rafts regulate HIV-1 Tat protein-induced activation of the Rho signaling and upregulation of P-glycoprotein in brain endothelial cells.
The Rho signaling has an essential function in human immunodeficiency virus (HIV)-1-mediated disruption of the integrity of the blood-brain barrier (BBB). However, it is unknown how membrane domains, such as lipid rafts, can influence HIV-1-mediated activation of the Rho pathway and how these processes can affect the expression of the efflux transporters at the BBB level. This study is focused on the function of HIV-1 protein Tat in activation of the Rho signaling and upregulation of P-glycoprotein (P-gp) in human brain endothelial cells. Treatment with Tat markedly elevated GTP-RhoA levels and the potential downstream effectors, such as myosin phosphatase target subunit 1 and myosin light chain. In addition, Tat upregulated expression and promoter activity of P-gp as well as its efflux function. Inhibition of the Rho signaling cascade effectively blocked P-gp overexpression at the level of promoter activity. Disruption of lipid rafts by depletion of membrane cholesterol by methyl-beta-cyclodextrin, but not caveolin-1 silencing, also abolished Tat-mediated RhoA activation and P-gp upregulation. The present data indicate the critical function of intact lipid rafts and the Rho signaling in HIV-1-mediated upregulation of P-gp and potential development of drug resistance in brain endothelial cells.
Department of Neurosurgery, Molecular Neuroscience and Vascular Biology Laboratory, University of Kentucky Medical Center, Lexington, Kentucky 40536, USA.
Yu
Y
Zhong
Bernhard
B
Hennig
Michal
M
Toborek
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis*; D000256:Adenoviridae / Q000276:immunology; D015153:Blotting, Western; D001921:Brain / Q000166:cytology; D051242:Caveolin 1 / Q000235:genetics / Q000502:physiology; D002478:Cells, Cultured; D002560:Cerebrovascular Circulation / Q000502:physiology; D002784:Cholesterol / Q000502:physiology; D042783:Endothelial Cells / Q000378:metabolism* / Q000502:physiology; D005456:Fluorescent Dyes; D005822:Genetic Vectors; D015497:HIV-1 / Q000378:metabolism*; D006801:Humans; D021962:Membrane Microdomains / Q000502:physiology*; D018994:Myosin Light Chains / Q000378:metabolism; D011401:Promoter Regions, Genetic; D020112:Rhodamine 123; D015398:Signal Transduction / Q000502:physiology*; D015854:Up-Regulation; D020741:rho GTP-Binding Proteins / Q000502:physiology*; D054322:tat Gene Products, Human Immunodeficiency Virus / Q000502:physiology*
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D051242:Caveolin 1; D005456:Fluorescent Dyes; D018994:Myosin Light Chains; D054322:tat Gene Products, Human Immunodeficiency Virus; D020112:Rhodamine 123; D002784:Cholesterol; D020741:rho GTP-Binding Proteins