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Updated: Jun 8, 2025
06:43
Functional Assessment of Intestinal Tight Junction Barrier and Ion Permeability in Native Tissue by Ussing Chamber Technique
Published on: May 26, 2021
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Structure-function analysis of tight junction-directed permeation enhancer PIP250
Alistair Taverner1, Khaled Almansour2, Kate Gridley1
1Department of Life Sciences, Centre for Therapeutic Innovation, University of Bath, Bath BA2 7AY, UK.
Summary
A novel peptide, PIP250, enhances intestinal drug absorption by modulating tight junctions. This permeation enhancer targets protein phosphatase 1 (PP1) interactions, improving oral delivery of poorly absorbed medications.
Area of Science:
- Cell Biology
- Pharmacology
- Biochemistry
Background:
- Intestinal absorption is regulated by tight junctions (TJs) between epithelial cells.
- TJ regulation involves phosphorylation of myosin light chain (MLC) by MLC kinase (MLCK) and MLC phosphatase (MLCP).
- MLCP comprises protein phosphatase 1 (PP1) and myosin targeting protein 1 (MYPT1).
Purpose of the Study:
- To investigate the effect of a novel peptide, PIP250, on intestinal barrier function and drug absorption.
- To identify key amino acids in PIP250 responsible for its interaction with PP1 and MYPT1.
Main Methods:
- Design and synthesis of a D-amino acid peptide (PIP250) to inhibit PP1-MYPT1 interaction.
- In vitro assessment of PIP250 effects on TJ protein expression, pMLC levels, and epithelial barrier function.
- In vivo studies evaluating PIP250's impact on gentamicin absorption.
- Analysis of PIP250 analogues to determine critical amino acid residues.
Main Results:
- PIP250 localized to intracellular TJ structures and altered TJ protein expression.
- PIP250 increased cellular pMLC levels and bound to PP1.
- PIP250 decreased epithelial barrier function and significantly enhanced in vivo gentamicin absorption.
- Specific amino acid positions (Phe3, Val5) in PIP250 were critical for its function.
Conclusions:
- PIP250 acts as a rationally designed oral permeation enhancer.
- The study validated key amino acids in PIP250's interaction with PP1.
- PIP250's efficacy is linked to its MYPT1-mimetic properties and modulation of TJ dynamics.
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