title: Cell surface clustering of heparan sulfate proteoglycans by amphipathic cell-penetrating peptides does not contribute to uptake.
abstract: For arginine-rich cell-penetrating peptides (CPPs), an association with heparan sulfate (HS) chains is considered the first step in the stimulation of uptake for many cells. Much less is known about the role of HS chains in the cell-association and internalization of arginine-free amphipathic CPP such as transportan-10 (TP10). Here, we report that various TP10 analogs differ in their capacity to accumulate on HS-rich plasma membranes in an HS-dependent manner. No accumulation was observed on HS-poor plasma membranes or when HS was removed by enzymatic cleavage. The TP10 analog that strongly clustered on the cell surface, also showed a pronounced capacity to form clusters with HS chains in solution. However, aggregation occurred in a thermodynamically different way compared to the interaction of arginine-rich CPP with HS. To monitor the impact of the peptide on the aggregation of the glycocalyx by time-lapse microscopy, sialic acids were visualized by metabolic labeling using copper-free click chemistry to attach fluorophores to metabolically incorporated azido sugars. Strikingly, a highly enhanced HS-mediated accumulation on the plasma membrane of a particular TP10 analog did not correlate with a better uptake. These findings illustrate that the mode of interaction between cell-penetrating peptides and HS chains has important functional consequences regarding peptide internalization and that there is no direct coupling of interaction, accumulation and uptake.
authors.affiliation: Department of Biochemistry, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Post 286, PO Box 9101, 6500 HB Nijmegen, The Netherlands.
authors.forename: Wouter P R
authors.initials: WP
authors.lastname: Verdurmen
authors.forename: Rike
authors.initials: R
authors.lastname: Wallbrecher
authors.forename: Samuel
authors.initials: S
authors.lastname: Schmidt
authors.forename: Jos
authors.initials: J
authors.lastname: Eilander
authors.forename: Petra
authors.initials: P
authors.lastname: Bovee-Geurts
authors.forename: Susanne
authors.initials: S
authors.lastname: Fanghänel
authors.forename: Jochen
authors.initials: J
authors.lastname: Bürck
authors.forename: Parvesh
authors.initials: P
authors.lastname: Wadhwani
authors.forename: Anne S
authors.initials: AS
authors.lastname: Ulrich
authors.forename: Roland
authors.initials: R
authors.lastname: Brock
mesh_terms: D002462:Cell Membrane / Q000378:metabolism*; D057846:Cell-Penetrating Peptides / Q000494:pharmacology*; D006367:HeLa Cells; D019812:Heparan Sulfate Proteoglycans / Q000378:metabolism*; D006801:Humans; D019169:Jurkat Cells; D011993:Recombinant Fusion Proteins / Q000494:pharmacology*
chemical_list: D057846:Cell-Penetrating Peptides; D019812:Heparan Sulfate Proteoglycans; D011993:Recombinant Fusion Proteins; C586078:transportan-10