Preliminary Results for TAT-Mediated Photoactivatable Cell Delivery
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Protein delivery into cells is often achieved through use of cell-penetrating peptides (CPPs). TAT (an HIV peptide) is one of the most efficient CPPs and, when incubated with cells, induces macropinocytosis of the surrounding medium. This brings coincubated extracellular cargo into endosomes, where they often remain trapped without outside stimulus. We hypothesized that TMR conjugated to TAT could induce medium uptake and, when photoactivated by light treatment, cause endosomal release of cargo. We performed several experiments using TMR-TAT and eGFP cargo at various conditions, but initial trials show no detectable delivery. Though our results are only preliminary, we have observed several phenomena that inhibit delivery and/or detection of delivery, including low endosomal uptake and release, fluorescent CPP adherence to the dish surface, and high cell death and buildup of cellular debris. In future trials, we plan to correct these issues by modifying reagent concentrations, using different reagents, and changing intensity of light treatment. In summary, we believe delivery is still possible after changing various parameters. If future trials are successful, TMRTAT and cargo coincubation may prove to be an efficient method to deliver therapeutic proteins and has implications in patient drug treatment and in vitro cell modulation.
Grunewald, Matthew (2011). Preliminary Results for TAT-Mediated Photoactivatable Cell Delivery. Honors and Undergraduate Research. Available electronically from