Metabolic cleavage of cell-penetrating peptides in contact with epithelial models: human calcitonin (hCT)-derived peptides, Tat(47-57) and penetratin(43-58)

Rachel Tréhin, Hanne Mørck Nielsen, Heinz-Georg Jahnke, Ulrike Krauss, Annette G. Beck-Sickinger, Hans P Merkle

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    Abstract

    We assessed the metabolic degradation kinetics and cleavage patterns of some selected CPP (cell-penetrating peptides) after incubation with confluent epithelial models. Synthesis of N-terminal CF [5(6)-carboxyfluorescein]-labelled CPP, namely hCT (human calcitonin)-derived sequences, Tat(47-57) and penetratin(43-58), was through Fmoc (fluoren-9-ylmethoxycarbonyl) chemistry. Metabolic degradation kinetics of the tested CPP in contact with three cell-cultured epithelial models, MDCK (Madin-Darby canine kidney), Calu-3 and TR146, was evaluated by reversed-phase HPLC. Identification of the resulting metabolites of CF-hCT(9-32) was through reversed-phase HPLC fractionation and peak allocation by MALDI-TOF-MS (matrix-assisted laser-desorption ionization-time-of-flight mass spectrometry) or direct MALDI-TOF-MS of incubates. Levels of proteolytic activity varied highly between the investigated epithelial models and the CPP. The Calu-3 model exhibited the highest proteolytic activity. The patterns of metabolic cleavage of hCT(9-32) were similar in all three models. Initial cleavage of this peptide occurred at the N-terminal domain, possibly by endopeptidase activity yielding both the N- and the C-terminal counterparts. Further metabolic degradation was by aminopeptidase, endopeptidase and/or carboxypeptidase activities. In conclusion, when in contact with epithelial models, the studied CPP were subject to efficient metabolism, a prerequisite of cargo release on the one hand, but with potential for premature cleavage and loss of the cargo as well on the other. The results, particularly on hCT(9-32), may be used as a template to suggest structural modifications towards improved CPP performance.
    Original languageEnglish
    JournalBiochemical Journal
    Volume382
    Issue numberPt 3
    Pages (from-to)945-56
    Number of pages12
    ISSN0264-6021
    DOIs
    Publication statusPublished - 2004

    Keywords

    • Amino Acid Sequence
    • Animals
    • Biotransformation
    • Calcitonin
    • Cell Line
    • Chromatography, High Pressure Liquid
    • Dogs
    • Drug Carriers
    • Epithelial Cells
    • Gene Products, tat
    • Homeodomain Proteins
    • Humans
    • Kinetics
    • Molecular Sequence Data
    • Molecular Weight
    • Peptide Fragments
    • Structure-Activity Relationship
    • tat Gene Products, Human Immunodeficiency Virus

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