title: HIV-1 Tat-mediated effects on focal adhesion assembly and permeability in brain microvascular endothelial cells.
abstract: The blood-brain barrier (BBB) is a network formed mainly by brain microvascular endothelial cells (BMECs). The integrity of the BBB is critical for brain function. Breakdown of the BBB is commonly seen in AIDS patients with HIV-1-associated dementia despite the lack of productive HIV infection of the brain endothelium. The processes by which HIV causes these pathological conditions are not well understood. In this study we characterized the molecular mechanisms by which Tat mediates its pathogenic effects in vitro on primary human BMECs (HBMECs). Tat treatment of HBMECs stimulated cytoskeletal organization and increased focal adhesion sites compared with control cells or cells treated with heat-inactivated Tat. Pretreatment with Tat Abs or with the specific inhibitor SU-1498, which interferes with vascular endothelial growth factor receptor type 2 (Flk-1/KDR) phosphorylation, blocked the ability of Tat to stimulate focal adhesion assembly and the migration of HBMECs. Focal adhesion kinase (FAK) was tyrosine-phosphorylated by Tat and was found to be an important component of focal adhesion sites. Inhibition of FAK by the dominant interfering mutant form, FAK-related nonkinase, significantly blocked HBMEC migration and disrupted focal adhesions upon Tat activation. Furthermore, HIV-Tat induced permeability changes in HBMECs in a time-dependent manner. Tat also impaired BBB permeability, as observed in HIV-1 Tat transgenic mice. These studies define a mechanism for HIV-1 Tat in focal adhesion complex assembly in HBMECs via activation of FAK, leading to cytoskeletal reorganization and permeability changes.
authors.affiliation: Division of Experimental Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, 4 Blackfan Circle, Boston, MA 02115, USA.
authors.forename: Hava Karsenty
authors.initials: HK
authors.lastname: Avraham
authors.forename: Shuxian
authors.initials: S
authors.lastname: Jiang
authors.forename: Tae-Hee
authors.initials: TH
authors.lastname: Lee
authors.forename: Om
authors.initials: O
authors.lastname: Prakash
authors.forename: Shalom
authors.initials: S
authors.lastname: Avraham
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D001921:Brain / Q000098:blood supply* / Q000166:cytology* / Q000201:enzymology; D002463:Cell Membrane Permeability / Q000502:physiology*; D002464:Cell Migration Inhibition; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology* / Q000201:enzymology / Q000378:metabolism*; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D022001:Focal Adhesions / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D015696:Gene Products, tat / Q000235:genetics / Q000502:physiology*; D049452:Green Fluorescent Proteins / Q000235:genetics; D015497:HIV-1 / Q000502:physiology*; D006801:Humans; D016023:Integrins / Q000502:physiology; D051379:Mice; D008822:Mice, Transgenic; D008833:Microcirculation / Q000166:cytology / Q000201:enzymology / Q000378:metabolism; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D014443:Tyrosine / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000502:physiology; D054322:tat Gene Products, Human Immunodeficiency Virus
chemical_list: D015696:Gene Products, tat; D016023:Integrins; D042461:Vascular Endothelial Growth Factor A; C485192:green fluorescent protein, Aequorea victoria; D054322:tat Gene Products, Human Immunodeficiency Virus; D049452:Green Fluorescent Proteins; D014443:Tyrosine; C113183:FAK-related nonkinase; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496050:PTK2 protein, human; C496051:Ptk2 protein, mouse