title: Signaling mechanisms of HIV-1 Tat-induced alterations of claudin-5 expression in brain endothelial cells.
abstract: Exposure of brain microvascular endothelial cells (BMEC) to human immunodeficiency virus-1 (HIV-1) Tat protein can decrease expression and change distribution of tight junction proteins, including claudin-5. Owing to the importance of claudin-5 in maintaining the blood-brain barrier (BBB) integrity, the present study focused on the regulatory mechanisms of Tat-induced alterations of claudin-5 mRNA and protein levels. Real-time reverse-transcription-polymerase chain reaction revealed that claudin-5 mRNA was markedly diminished in BMEC exposed to Tat. However, U0126 (an inhibitor of mitogen-activated protein kinase kinase1/2, MEK1/2) protected against this effect. In addition, inhibition of the vascular endothelial growth factor receptor type 2 (VEGFR-2) by SU1498, phosphatidylinositol-3 kinase (PI-3 K) by LY294002, nuclear factor-kappaB (NF-kappaB) by peptide SN50, and intracellular calcium by BAPTA/AM partially prevented Tat-mediated alterations in claudin-5 protein levels and immunoreactivity patterns. In contrast, inhibition of protein kinase C did not affect claudin-5 expression in Tat-treated cells. The present findings indicate that activation of VEGFR-2 and multiple redox-regulated signal transduction pathways are involved in Tat-induced alterations of claudin-5 expression. Because claudins constitute the major backbone of tight junctions, the present data are relevant to the disturbances of the BBB in the course of HIV-1 infection.
authors.affiliation: Department of Surgery, University of Kentucky, Lexington, Kentucky 40536, USA.
authors.forename: Ibolya E
authors.initials: IE
authors.lastname: András
authors.forename: Hong
authors.initials: H
authors.lastname: Pu
authors.forename: Jing
authors.initials: J
authors.lastname: Tian
authors.forename: Mária A
authors.initials: MA
authors.lastname: Deli
authors.forename: Avindra
authors.initials: A
authors.lastname: Nath
authors.forename: Bernhard
authors.initials: B
authors.lastname: Hennig
authors.forename: Michal
authors.initials: M
authors.lastname: Toborek
mesh_terms: D000818:Animals; D015153:Blotting, Western; D001923:Brain Chemistry / Q000187:drug effects*; D002118:Calcium / Q000494:pharmacology; D002478:Cells, Cultured; D002614:Chelating Agents / Q000494:pharmacology; D062507:Claudin-5; D015536:Down-Regulation / Q000502:physiology; D042783:Endothelial Cells / Q000187:drug effects*; D015696:Gene Products, tat / Q000494:pharmacology*; D011905:Genes, ras / Q000235:genetics; D015497:HIV-1 / Q000378:metabolism*; D008565:Membrane Proteins / Q000096:biosynthesis*; D008856:Microscopy, Fluorescence; D016328:NF-kappa B / Q000187:drug effects / Q000502:physiology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism; D054322:tat Gene Products, Human Immunodeficiency Virus
chemical_list: D002614:Chelating Agents; D062507:Claudin-5; C491510:Cldn5 protein, rat; D015696:Gene Products, tat; D008565:Membrane Proteins; D016328:NF-kappa B; D012333:RNA, Messenger; D054322:tat Gene Products, Human Immunodeficiency Virus; D040301:Vascular Endothelial Growth Factor Receptor-2; D002118:Calcium