title: Molecular determinants for cellular uptake of Tat protein of human immunodeficiency virus type 1 in brain cells.
abstract: We measured the cellular uptake of 125I-labeled full-length Tat (amino acids 1 to 86) (125I-Tat(1-86)) and 125I-Tat(1-72) (first exon) in human fetal astrocytes, neuroblastoma cells, and human fetal neurons and demonstrated that the uptake of 125I-Tat(1-72) without the second exon was much lower than that of 125I-Tat(1-86) (P < 0.01). This suggests an important role for the C-terminal region of Tat for its cellular uptake. 125I-Tat uptake could be inhibited by dextran sulfate and competitively inhibited by unlabeled Tat but not by overlapping 15-mer peptides, suggesting that Tat internalization is charge and conformationally dependent. Interestingly, one of 15-mer peptides, Tat(28-42), greatly enhanced 125I-Tat uptake. These findings are important for understanding the neuropathogenesis of human immunodeficiency virus type 1 infection and in the potential application of Tat for drug delivery to cells.
authors.affiliation: Department of Medical Microbiology, University of Manitoba, Winnipeg, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Ma
authors.forename: A
authors.initials: A
authors.lastname: Nath
mesh_terms: D000595:Amino Acid Sequence; D001253:Astrocytes / Q000166:cytology / Q000378:metabolism*; D001921:Brain / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D002460:Cell Line; D016264:Dextran Sulfate / Q000494:pharmacology; D015696:Gene Products, tat / Q000493:pharmacokinetics*; D015497:HIV-1 / Q000378:metabolism*; D006801:Humans; D016023:Integrins / Q000378:metabolism; D008969:Molecular Sequence Data; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D054322:tat Gene Products, Human Immunodeficiency Virus
chemical_list: D015696:Gene Products, tat; D016023:Integrins; D054322:tat Gene Products, Human Immunodeficiency Virus; D016264:Dextran Sulfate