The Non-Peptidic Part Determines the Internalization Mechanism and Intracellular Trafficking of Peptide Amphiphiles

Abstract

BackgroundPeptide amphiphiles (PAs) are a class of amphiphilic molecules able to self-assemble into nanomaterials that have shown efficient in vivo targeted delivery. Understanding the interactions of PAs with cells and the mechanisms of their internalization and intracellular trafficking is critical in their further development for therapeutic delivery applications.Methodology/Principal FindingsPAs of a novel, cell- and tissue-penetrating peptide were synthesized possessing two different lipophilic tail architectures and their interactions with prostate cancer cells were studied in vitro. Cell uptake of peptides was greatly enhanced post-modification. Internalization occurred via lipid-raft mediated endocytosis and was common for the two analogs studied. On the contrary, we identified the non-peptidic part as the determining factor of differences between intracellular trafficking and retention of PAs. PAs composed of di-stearyl lipid tails linked through poly(ethylene glycol) to the peptide exhibited higher exocytosis rates and employed different recycling pathways compared to ones consisting of di-palmitic-coupled peptides. As a result, cell association of the former PAs decreased with time.Conclusions/SignificanceControl over peptide intracellular localization and retention is possible by appropriate modification with synthetic hydrophobic tails. We propose this as a strategy to design improved peptide-based delivery systems.

Cathepsin-Mediated Cleavage of Peptides from Peptide Amphiphiles Leads to Enhanced Intracellular Peptide Accumulation

“…Product identity was confirmed using matrix-assisted laser desorption–ionization (MALDI) mass spectrometry (Bruker Ultraflextreme MALDI-TOF), as previously described. 29 …”

Self-assembling peptide-based building blocks in medical applications

“…The hydrophobic tails of PAs promote cellular membrane anchoring and internalization and because of their dynamic structure, individual monomers can escape and insert their tails into other hydrophobic compartments [35,36]. Advantages of micelle-based peptide delivery systems are (i) delivery of a high concentration of peptide to its target (60–90% of the introduced concentration) [37], (ii) stabilization of peptide secondary structure (e.g. α-helices) [38,39], (iii) protection from proteolytic degradation [40,41], (iv) modular building potential to target malignant cells, and (v) the ability to load with multiple different amphiphiles directed at non-redundant protein-protein interaction (PPI) targets.…”

Modular Peptide Amphiphile Micelles Improving an Antibody-Mediated Immune Response to Group A Streptococcus

“…21 Interestingly, PAMs stimulated a stronger antibody response than peptide alone without the use of an adjuvant making it a self-adjuvanting device. Furthermore, while the hydrophobic tails enhance cell uptake by anchoring into cell membranes, 22 they do not act as pathogen recognition receptor (PRR) agonists and therefore do not function as molecular adjuvants. 21 Rather, it is thought to be the self-assembled, particular-based physical nature of PAMs that affords them immunogenicity.…”