title: Relating structure and internalization for ROMP-based protein mimics.
abstract: Elucidating the predominant cellular entry mechanism for protein transduction domains (PTDs) and their synthetic mimics (PTDMs) is a complicated problem that continues to be a significant source of debate in the literature. The PTDMs reported here provide a well-controlled platform to vary molecular composition for structure activity relationship studies to further our understanding of PTDs, their non-covalent association with cargo, and their cellular internalization pathways. Specifically, several guanidine rich homopolymers, along with an amphiphilic block copolymer were used to investigate the relationship between structure and internalization activity in HeLa cells, both alone and non-covalently complexed with EGFP by flow cytometery and confocal imaging. The findings indicate that while changing the amount of positive charge on our PTDMs does not seem to affect the endosomal uptake, the presence of hydrophobicity appears to be a critical factor for the polymers to enter cells either alone, or with associated cargo.
authors.affiliation: Department of Polymer Science & Engineering, University of Massachusetts, Amherst, MA 01003, USA.
authors.forename: Coralie M
authors.initials: CM
authors.lastname: Backlund
authors.affiliation: Department of Veterinary & Animal Sciences, University of Massachusetts, Amherst, MA 01003, USA.
authors.forename: Toshihide
authors.initials: T
authors.lastname: Takeuchi
authors.affiliation: Molecular and Cellular Biology Program, University of Massachusetts, Amherst, MA 01003, USA.
authors.forename: Shiroh
authors.initials: S
authors.lastname: Futaki
authors.affiliation: Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.
authors.forename: Gregory N
authors.initials: GN
authors.lastname: Tew
mesh_terms: D057846:Cell-Penetrating Peptides / Q000737:chemistry / Q000378:metabolism; D004705:Endocytosis / Q000502:physiology*; D011992:Endosomes / Q000378:metabolism*; D005434:Flow Cytometry; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006146:Guanidines / Q000138:chemical synthesis / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D057786:Peptidomimetics / Q000138:chemical synthesis / Q000378:metabolism*; D011108:Polymers / Q000138:chemical synthesis / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D055672:Static Electricity; D013329:Structure-Activity Relationship
chemical_list: D057846:Cell-Penetrating Peptides; D006146:Guanidines; D057786:Peptidomimetics; D011108:Polymers; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins
keywords: Cell-penetrating peptide; Internalization; Protein transduction domains; TAT