alpha(v)beta3-integrin-dependent activation of focal adhesion kinase mediates NF-kappaB activation and motogenic activity by HIV-1 Tat in endothelial cells.
Once in the extracellular environment, the transactivator protein HIV-1 Tat exerts several pleiotropic effects by interacting with different cellular receptors, including integrin alpha(v)beta3. Real-time surface plasmon resonance analysis reveals that Tat/alpha(V)beta3 interaction occurs with rapid kinetics (association and dissociation rates equal to 1.16 x 10(7) M(-1) s(-1) and 3.78 x 10(-1) s(-1), respectively) and high affinity (dissociation constant = 32 nM). Through this interaction, substratum-immobilized Tat promotes adhesion and motogenic activity in endothelial cells. Also, alpha(v)beta(3)/Tat interaction triggers the activation of focal adhesion kinase, RhoA and pp60src. Overexpression of the dominant negative form of focal adhesion kinase, but not of an inactive Leu1034Ser substitution mutant isoform, impairs the activation of focal adhesion kinase and RhoA, but not that of pp60src, without affecting endothelial cell adhesion and spreading. alpha(v)beta3/Tat interaction triggers the activation of NF-kappaB in endothelial cells in a focal adhesion kinase-, RhoA- and pp60src-dependent manner, as shown in dominant negative focal adhesion kinase transfectants or using specific pharmacological inhibitors. Finally, the activation of focal adhesion kinase, RhoA, NF-kappaB and pp60src are required to mediate the motogenic activity of Tat in endothelial cells. Since Tat accumulates in an immobilized form in the extracellular matrix, these results provide new biochemical and biological insights about alpha(v)beta3/Tat interaction exploitable for the design of anti-Tat strategies.
Urbinati
Chiara
C
General Pathology and Immunology, Department of Biomedical Sciences and Biotechnology, School of Medicine, University of Brescia, viale Europe 11, 25123 Brescia, Italy.
Bugatti
Antonella
A
Giacca
Mauro
M
Schlaepfer
David
D
Presta
Marco
M
Rusnati
Marco
M
D000818:Animals; D002417:Cattle; D002448:Cell Adhesion / Q000502:physiology; D002460:Cell Line; D002465:Cell Movement / Q000502:physiology*; D002474:Cell-Free System; D042783:Endothelial Cells / Q000166:cytology / Q000502:physiology*; D004789:Enzyme Activation; D015696:Gene Products, tat / Q000235:genetics / Q000378:metabolism*; D015497:HIV-1 / Q000378:metabolism*; D006801:Humans; D039302:Integrin alphaVbeta3 / Q000235:genetics / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism*; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000378:metabolism; D020349:Surface Plasmon Resonance; D020742:rhoA GTP-Binding Protein / Q000378:metabolism; D054322:tat Gene Products, Human Immunodeficiency Virus
D015696:Gene Products, tat; D039302:Integrin alphaVbeta3; D016328:NF-kappa B; D054322:tat Gene Products, Human Immunodeficiency Virus; D016392:Proto-Oncogene Proteins pp60(c-src); D020742:rhoA GTP-Binding Protein