Tat-mediated delivery of heterologous proteins into cells.

TLDR

The Tat protein of HIV‑1 can enter cells efficiently when added exogenously in tissue culture. The study aimed to determine whether Tat peptides could transport heterologous proteins into cells. Researchers cross‑linked Tat peptides (residues 1‑72 or 37‑72) to β‑galactosidase, horseradish peroxidase, RNase A, and Pseudomonas exotoxin A domain III, then measured cellular uptake colorimetrically or via cytotoxicity. Tat–protein chimeras were taken up by all tested cell types and delivered to multiple mouse tissues, especially endothelial and macrophage‑rich regions, indicating that Tat can facilitate therapeutic delivery of previously impermeable macromolecules.

Abstract

The Tat protein of human immunodeficiency virus 1 (HIV-1) can enter cells efficiently when added exogenously in tissue culture. To assess if Tat can carry other molecules into cells, we chemically cross-linked Tat peptides (residues 1-72 or 37-72) to beta-galactosidase, horseradish peroxidase, RNase A, and domain III of Pseudomonas exotoxin A (PE) and monitored uptake colorimetrically or by cytotoxicity. The Tat chimeras were effective on all cell types tested, with staining showing uptake into all cells in each experiment. In mice, treatment with Tat-beta-galactosidase chimeras resulted in delivery to several tissues, with high levels in heart, liver, and spleen, low-to-moderate levels in lung and skeletal muscle, and little or no activity in kidney and brain. The primary target within these tissues was the cells surrounding the blood vessels, suggesting endothelial cells, Kupffer cells, and/or splenic macrophages. Tat-mediated uptake may allow the therapeutic delivery of macromolecules previously thought to be impermeable to living cells.