title: BSA conjugates bearing multiple copies of the basic domain of HIV-1 Tat: Prototype for the development of multitarget inhibitors of extracellular Tat.
abstract: The transactivating factor (Tat) of HIV-1 is involved in AIDS progression and associated pathologies. Tat possesses a basic amino acid sequence implicated in heparan sulfate proteoglycan (HSPG)-mediated internalization, nuclear localization and transactivation by Tat and in the interaction of Tat with integrins and with the vascular endothelial growth factor receptor 2 (KDR) (kinase insert domain receptor). A BSA conjugate bearing an average of four copies of a peptide representing the basic domain/nuclear localization signal of Tat (BSA-Tat-NLS) inhibits transactivation by Tat exogenously added to cells but not by Tat endogenously produced after cell transfection with a tat cDNA, indicating that BSA-Tat-NLS does not interfere with Tat at an intracellular level. Surface plasmon resonance (SPR) experiments revealed that BSA-Tat-NLS binds to the HSPG analogue heparin. Accordingly, BSA-Tat-NLS binds to HSPGs of HL3T1 cell surface and inhibits HSPG-dependent Tat internalization. BSA-Tat-NLS retains its inhibitory potential when pre-incubated with HL3T1 cells before Tat administration, possibly by masking cell-surface HSPGs thus preventing Tat binding and internalization. SPR experiments revealed that BSA-Tat-NLS binds also to integrin alpha(v)beta(3) and KDR. Accordingly, it inhibits pro-angiogenic endothelial cell adhesion to Tat and motogenesis. In conclusion, BSA-Tat-NLS binds/masks three different cell-surface receptors of Tat inhibiting different biological activities. These data point to BSA-Tat-NLS as a prototype for the development of Tat-antagonists endowed with a multitargeted mechanism of action.
authors.affiliation: Department of Biomedical Science and Biotechnology, University of Brescia, Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: Bugatti
authors.forename: Paola
authors.initials: P
authors.lastname: Chiodelli
authors.forename: Joseph
authors.initials: J
authors.lastname: Rosenbluh
authors.forename: Abraham
authors.initials: A
authors.lastname: Loyter
authors.forename: Marco
authors.initials: M
authors.lastname: Rusnati
mesh_terms: D023581:HIV Fusion Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D015497:HIV-1 / Q000187:drug effects* / Q000502:physiology; D006367:HeLa Cells; D006493:Heparin / Q000378:metabolism; D006801:Humans; D011485:Protein Binding; D012710:Serum Albumin, Bovine / Q000737:chemistry / Q000494:pharmacology*; D020349:Surface Plasmon Resonance; D053586:Virus Internalization / Q000187:drug effects*; D054322:tat Gene Products, Human Immunodeficiency Virus / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D023581:HIV Fusion Inhibitors; D054322:tat Gene Products, Human Immunodeficiency Virus; D012710:Serum Albumin, Bovine; D006493:Heparin