Integrin alphavbeta3 as a target for blocking HIV-1 Tat-induced endothelial cell activation in vitro and angiogenesis in vivo.
OBJECTIVE
The transactivating factor (Tat) of HIV-1 binds to alphavbeta3 integrin present on endothelial cells contributing to neovascularization. Here, we investigated the biological consequences of Tat/alphavbeta3 interaction and the antagonist effect of an Arg-Gly-Asp (RGD)-based peptidomimetic.


RESULTS
Binding of Tat to endothelial alphavbeta3 triggers focal adhesion kinase and nuclear factor-kappaB activation, leading to endothelial cell proliferation, membrane ruffling, and motility in vitro and neovascularization in vivo. The RGD-peptidomimetic SCH221153 inhibits Tat/alphavbeta3 interaction in a solid phase binding assay and endothelial cell adhesion to immobilized Tat with a potency higher than that of RGD-containing peptides. Accordingly, SCH221153 inhibits Tat/alphavbeta3-dependent focal adhesion kinase and nuclear factor-kappaB activation, proliferation, membrane ruffling, and motility in endothelial cells. Finally, SCH221153 inhibits the angiogenic response triggered by Tat in the chick-embryo chorioallantoic membrane without affecting physiological vascularization. SCH221153 exerts these inhibitory effects without affecting the interaction of Tat with endothelial heparan sulfate proteoglycans or with the vascular endothelial growth factor receptor-2/kinase domain-containing receptor. In all the assays the negative control SCH216687 was ineffective.


CONCLUSIONS
These data provide new insights on the mechanism of endothelial cell activation by Tat and point to RGD peptidomimetics as prototypes for the development of novel Tat antagonists.
Urbinati
Chiara
C
Department of Biomedical Sciences and Biotechnology, University of Brescia, Italy.
Mitola
Stefania
S
Tanghetti
Elena
E
Kumar
Chandra
C
Waltenberger
Johannes
J
Ribatti
Domenico
D
Presta
Marco
M
Rusnati
Marco
M
D000818:Animals; D001011:Aorta / Q000166:cytology; D001562:Benzimidazoles / Q000494:pharmacology; D002417:Cattle; D002461:Cell Line, Transformed; D002642:Chick Embryo; D002645:Chickens; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000821:virology; D015696:Gene Products, tat / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015658:HIV Infections / Q000188:drug therapy / Q000378:metabolism / Q000503:physiopathology*; D015497:HIV-1; D006801:Humans; D066298:In Vitro Techniques; D039302:Integrin alphaVbeta3 / Q000378:metabolism*; D009389:Neovascularization, Pathologic / Q000188:drug therapy / Q000378:metabolism / Q000821:virology*; D009842:Oligopeptides / Q000378:metabolism; D010446:Peptide Fragments / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D013552:Swine; D014471:Umbilical Veins / Q000166:cytology; D054322:tat Gene Products, Human Immunodeficiency Virus
D001562:Benzimidazoles; D015696:Gene Products, tat; D039302:Integrin alphaVbeta3; D009842:Oligopeptides; D010446:Peptide Fragments; C423506:SCH 221153; D054322:tat Gene Products, Human Immunodeficiency Virus; C445078:tat peptide (17-25), Human immunodeficiency virus 1; C047981:arginyl-glycyl-aspartic acid