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Adsorptive-mediated endocytosis of a basic peptide in enterocyte-like Caco-2 cells

Y Sai1, M Kajita, I Tamai

  • 1Department of Pharmaceutics, Faculty of Pharmaceutical Sciences, Kanazawa University, Kanazawa 920-0934, Japan.

The American Journal of Physiology
|September 2, 1998
PubMed

Insights

The basic peptide 001-C8 is internalized by Caco-2 cells through adsorptive-mediated endocytosis. This process is time, temperature, and concentration-dependent, and influenced by specific inhibitors and cell surface molecules.

Area of Science:

  • Cell biology
  • Peptide transport
  • Biochemistry

Background:

  • Enterocyte-like Caco-2 cells are a model for intestinal absorption.
  • Understanding peptide uptake mechanisms is crucial for drug delivery.
  • The peptide 001-C8 is a basic peptide with potential therapeutic applications.

Purpose of the Study:

  • To investigate the mechanism of 001-C8 internalization into Caco-2 cells.
  • To characterize the kinetics and influencing factors of 001-C8 uptake.
  • To determine if 001-C8 uptake involves adsorptive-mediated endocytosis.

Main Methods:

  • Radiolabeling of 001-C8 with 125I for internalization assays.
  • Time- and concentration-dependent uptake studies at varying temperatures.
  • Inhibition studies using various compounds and enzyme treatments.
  • Confocal microscopy with a fluorescently labeled peptide (001-C8-NBD).

Main Results:

  • 001-C8 internalization increased with time, reaching steady state at 60 min.
  • Uptake was temperature and concentration dependent, with specific inhibitors (dansylcadaverine, protamine, poly-L-lysine) significantly reducing it.
  • Enzymatic predigestion of acid mucopolysaccharides also decreased internalization.
  • Confocal microscopy confirmed intracellular sequestration of 001-C8-NBD in endocytotic vesicles.

Conclusions:

  • 001-C8 is internalized by Caco-2 cells via adsorptive-mediated endocytosis.
  • The uptake mechanism involves interactions with cell surface components, possibly including acid mucopolysaccharides.
  • Inhibitor studies suggest a role for specific cellular pathways in 001-C8 transport.

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