CPP-protein constructs induce a population of non-acidic vesicles during trafficking through endo-lysosomal pathway

J Control Release. 2009 Oct 15;139(2):108-17. doi: 10.1016/j.jconrel.2009.06.028. Epub 2009 Jul 3.

Abstract

The major limitation in the application of bioactive molecules is their low permeation across plasma membrane. Effective transporters - cell-penetrating peptides (CPPs) - are utilized to enhance uptake of various cargo upon attachment to its sequences. Still, information about relevance of different endocytic routes during CPP-cargo internalization is ambiguous and underlying mechanism(s) of intracellular trafficking is even less understood. We first defined involvement of recycling pathway in trafficking of 3 different CPPs - transportan, oligoarginine and Tat - complexed to avidin-TexasRed in Cos-7 cells in relation to trans-Golgi network spatially constraining recycling endosomes. By confocal microscopy, only a negligible fraction of complexes-containing vesicles were found inside trans-Golgi ring suggesting its marginal role in CPP-mediated delivery. Secondly, we characterized engagement of endo-lysosomal pathway to assess acidity of complexes-containing vesicles. CPPs induced 3 different populations of complexes-containing vesicles which size and proportion depended on CPP, time and concentration. In time, more complexes were targeted to low-pH structures. However, a population of complexes-containing vesicles was observed to retain rather neutral pH. Induction of vesicles with non-acidic pH generated i.e. by caveolin-dependent endocytosis or by CPPs themselves during intracellular trafficking could be the key step in inducement of escape of complexes from endosomal structures, a limiting step in effective cargo delivery by CPPs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Avidin / chemistry
  • Avidin / pharmacokinetics*
  • COS Cells
  • Chlorocebus aethiops
  • Endocytosis*
  • Endosomes / metabolism
  • Golgi Apparatus / metabolism
  • Hydrogen-Ion Concentration
  • Lysosomes / metabolism
  • Molecular Sequence Data
  • Peptides / chemistry
  • Peptides / pharmacokinetics*
  • Protein Transport

Substances

  • Peptides
  • Avidin