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Updated: Jul 16, 2026

Production of Monoclonal Antibodies Targeting Aminopeptidase N in the Porcine Intestinal Mucosal Epithelium
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Production of Monoclonal Antibodies Targeting Aminopeptidase N in the Porcine Intestinal Mucosal Epithelium

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A novel monoclonal antibody against the second extracellular loop of occludin disrupts epithelial cell polarity

Yuichi Tokunaga1, Takashi Kojima, Makoto Osanai

  • 1Department of Pathology, Sapporo Medical University School of Medicine, S1, W17, Sapporo 060-8556, Japan.

The Journal of Histochemistry and Cytochemistry : Official Journal of the Histochemistry Society
|March 21, 2007
PubMed

Insights

The second extracellular loop of occludin is crucial for maintaining epithelial cell polarity and regulating protein localization at tight junctions. Blocking this loop disrupts cell polarity and protein distribution.

Area of Science:

  • Cell Biology
  • Epithelial Biology
  • Membrane Protein Trafficking

Background:

  • Tight junctions (TJs) are essential for epithelial cell polarity and control paracellular permeability.
  • Occludin is a key protein component of TJs, involved in regulating TJ structure and function.
  • The precise role of specific occludin domains, like the second extracellular loop, in TJ-mediated cell polarity is not fully understood.

Purpose of the Study:

  • To investigate the impact of the second extracellular loop of occludin on the localization of apical membrane proteins, carcinoembryonic antigen (CEA) and CD26.
  • To determine if targeting the second extracellular loop of occludin affects the fence function of tight junctions.
  • To elucidate the role of the occludin second extracellular loop in maintaining epithelial cell polarity.

Main Methods:

  • Utilized the human intestinal epithelial cell line T84.
  • Treated T84 cells with a monoclonal anti-occludin antibody (MAb 1H8) targeting the second extracellular loop of occludin.
  • Assessed the localization of occludin, CEA, and CD26, and evaluated TJ fence function and barrier function under various calcium conditions.

Main Results:

  • Treatment with MAb 1H8 led to occludin disappearance and diffusion of CEA and CD26 from apical to basolateral membranes.
  • A decrease in TJ fence function was observed without altering TJ strands or overall barrier function.
  • Recruitment of occludin and recovery of CEA/CD26 distribution were significantly delayed in cells treated with MAb 1H8 during calcium-induced TJ formation.

Conclusions:

  • The second extracellular loop of occludin selectively impacts the apical/basolateral intramembrane diffusion barrier.
  • The occludin second extracellular loop plays a critical role in maintaining epithelial cell polarity via tight junctions.
  • Targeting the occludin second extracellular loop offers a potential strategy to modulate TJ-dependent epithelial functions.

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