title: Spontaneous membrane-translocating peptides: influence of peptide self-aggregation and cargo polarity.
abstract: Peptides that translocate spontaneously across cell membranes could transform the field of drug delivery by enabling the transport of otherwise membrane-impermeant molecules into cells. In this regard, a 9-aminoacid-long motif (representative sequence: PLIYLRLLR, hereafter Translocating Motif 9, TM9) that spontaneously translocates across membranes while carrying a polar dye was recently identified by high-throughput screening. Here we investigate its transport properties by a combination of in cuvette physico-chemical assays, rational mutagenesis, live-cell confocal imaging and fluorescence correlation spectroscopy measurements. We unveil TM9 ability to self-aggregate in a concentration-dependent manner and demonstrate that peptide self-aggregation is a necessary--yet not sufficient--step for effective membrane translocation. Furthermore we show that membrane crossing can occur with apolar payloads while it is completely inhibited by polar ones. These findings are discussed and compared to previous reports. The present results impose a careful rethinking of this class of sequences as direct-translocation vectors suitable for delivery purposes.
authors.affiliation: NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza San Silvestro 12-56127 Pisa, Italy.
authors.forename: Sara
authors.initials: S
authors.lastname: Macchi
authors.affiliation: Center for Nanotechnology Innovation @NEST, Istituto Italiano di Tecnologia, Piazza San Silvestro 12-56127 Pisa, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Signore
authors.affiliation: Center for Nanotechnology Innovation @NEST, Istituto Italiano di Tecnologia, Piazza San Silvestro 12-56127 Pisa, Italy.
authors.forename: Claudia
authors.initials: C
authors.lastname: Boccardi
authors.affiliation: NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza San Silvestro 12-56127 Pisa, Italy.|Center for Nanotechnology Innovation @NEST, Istituto Italiano di Tecnologia, Piazza San Silvestro 12-56127 Pisa, Italy.
authors.forename: Carmine
authors.initials: C
authors.lastname: Di Rienzo
authors.affiliation: NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza San Silvestro 12-56127 Pisa, Italy.|Center for Nanotechnology Innovation @NEST, Istituto Italiano di Tecnologia, Piazza San Silvestro 12-56127 Pisa, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Beltram
authors.affiliation: Center for Nanotechnology Innovation @NEST, Istituto Italiano di Tecnologia, Piazza San Silvestro 12-56127 Pisa, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Cardarelli
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D002462:Cell Membrane / Q000378:metabolism*; D057846:Cell-Penetrating Peptides / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism*; D006224:Cricetinae; D003412:Cricetulus; D004058:Diffusion; D004337:Drug Carriers / Q000737:chemistry; D000067493:Dynamic Light Scattering; D005456:Fluorescent Dyes / Q000737:chemistry; D008823:Micelles; D018613:Microscopy, Confocal; D053758:Nanoparticles / Q000737:chemistry
chemical_list: D057846:Cell-Penetrating Peptides; D004337:Drug Carriers; D005456:Fluorescent Dyes; D008823:Micelles