New transport peptides broaden the horizon of applications for peptidic pharmaceuticals

Abstract

Protein transduction domains (PTDs) have proven to be an invaluable tool to transduce a wide variety of cargo's including peptides across the plasma membrane and into intact tissue. The PTDs are able to deliver biologically active molecules both in vitro and in vivo. This study describes many new polybasic PTDs of which some are just as potent as the PTDs derived from extracellular RNAses or other published PTDs. Large differences in potency became apparent when the PTDs are coupled to particular cargoes. Therefore, the unique characteristic of a PTD may only become apparent when it is selected for a particular application. Rules for optimization of PTDs for particular applications are now emerging and open the way for a new generation of drug delivery agents. Because fixation artifacts and irreversible membrane binding may cause misinterpretation of the amount of internalization of polybasic peptides, we have developed an enzyme transduction assay based on the intracellular loading of a cell permeable substrate. In this assay, a fluorescent signal is generated by internalized enzyme in intact cells and not by membrane-bound or extracellular enzyme.

Single-cell imaging of retinal ganglion cell apoptosis with a cell-penetrating, activatable peptide probe in an in vivo glaucoma model

“…Previously, the targeting of peptide-based imaging agents has been limited to extracellular or cell-surface targets because of the barrier function of the cellular membrane. However, efficient delivery of imaging probes to the cell interior using cell-penetrating peptides has greatly expanded potential applications for molecular imaging (26)(27)(28)(29)(30)(31), similar to advances with cell-penetrating peptides in therapy (32)(33)(34)(35). Delivery of optically quenched, activatable, peptide-based imaging probes to the intracellular compartment makes selective retention and signal amplification possible, improving sensitivity and signal-to-noise ratios, as well as increasing the number of biochemical processes that can be assessed.…”

Cryopreservation of Adherent Smooth Muscle and Endothelial Cells with Disaccharides

“…These protein transduction domains (PTDs) generally correspond to portions of native proteins. Examples of PTDs include the Tat protein from the human immunodeficiency virus type I, the envelope glycoprotein E rns from the pestivirus and the DNA binding domains of leucine zipper proteins such as c-fos, c-jun and yeast transcription factor GCN4 (Futaki et al, 2001(Futaki et al, , 2004Langedijk, 2002;Langedijk et al, 2004;Lindgren et al, 2000;Richard et al, 2003;Vives et al, 1997). These PTDs are short cationic peptides that cross the cell membrane in a concentration-dependent manner that is independent of specific receptors or other transporters.…”

“…Some studies have suggested that endocytosis is involved (Lundberg & Johansson, 2002;Richard et al, 2003), however, the current theory includes interaction with glycosaminoglycans and uptake by a non-endocytotic mechanism that may involve the charged heads of the phospholipid groups within the cell membrane. (Langedijk, 2002;Langedijk et al, 2004;Mai et al, 2002).…”

Membrane transducing activity of recombinant Hoxc8 protein and its possible application as a gene delivery vector

“…These PTDs have been shown to mediate the rapid cellular delivery of proteins (Lundberg et al, 2003) and peptides (Eum et al, 2005) and have been observed to possess the ability to traverse the lipid bilayer of cells in a concentration dependent manner (Langedijk et al, 2004). The exact mechanism of delivery is not fully understood, although the PTDs are generally known to undergo endocytosis (Drin et al, 2003;Ignatovich et al, 2003;Richard et al, 2003;Trehin and Merkle, 2004).…”