Evidence for neurotoxic activity of tat from human immunodeficiency virus type 1.
The human immunodeficiency virus (HIV) genome codes for a trans-activating regulatory protein, tat. Using chemically synthesized tat, it was found that 125I-tat and 125I-tat38-86 specifically bound to rat brain synaptosomal membranes with moderate affinity (K0.5 = 3 microM). Interaction of tat with nerve cells was also revealed by flow cytometry, which showed its binding to rat glioma and murine neuroblastoma cells, using both direct fluorescence with fluorescein isothiocyanate-labeled tat and indirect immunofluorescence assays. This interaction was investigated with electrophysiology using isolated excitable frog muscle fibers and cockroach giant interneuron synapses. tat acted on the cell membrane and induced a large depolarization, accompanied by a decrease in membrane resistance, thereby modifying cell permeability. The neurotoxicity of tat was further demonstrated in vitro, on glioma and neuroblastoma cell growth, as well as by a 51Cr release assay in both tumor cell lines. Interestingly, no hemolytic activity of tat for human erythrocytes was found even when tat was tested at its highly neurotoxic concentration. Experiments in vivo showed that synthetic tat is a potent and lethal neurotoxic agent in mice. The use of tat peptide derivatives showed that basic region from 49 to 57 is necessary and sufficient for binding to cell membranes and toxicity.
Sabatier
J M
JM
Laboratoire de Biochimie, Centre National de la Recherche Scientifique URA 1179, Faculté de Médecine, Marseille, France.
Vives
E
E
Mabrouk
K
K
Benjouad
A
A
Rochat
H
H
Duval
A
A
Hue
B
B
Bahraoui
E
E
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D003058:Cockroaches; D016650:Fluorescein-5-isothiocyanate; D005452:Fluoresceins; D005456:Fluorescent Dyes; D015696:Gene Products, tat / Q000378:metabolism / Q000494:pharmacology*; D005910:Glioma; D015497:HIV-1 / Q000235:genetics / Q000472:pathogenicity*; D066298:In Vitro Techniques; D007395:Interneurons / Q000187:drug effects / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D009132:Muscles / Q000187:drug effects / Q000502:physiology*; D009447:Neuroblastoma; D009498:Neurotoxins; D011898:Ranidae; D051381:Rats; D013569:Synapses / Q000187:drug effects / Q000502:physiology; D013861:Thiocyanates; D054322:tat Gene Products, Human Immunodeficiency Virus
D005452:Fluoresceins; D005456:Fluorescent Dyes; D015696:Gene Products, tat; D009498:Neurotoxins; D013861:Thiocyanates; D054322:tat Gene Products, Human Immunodeficiency Virus; D016650:Fluorescein-5-isothiocyanate