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Experimental Models for Study of Retinal Pigment Epithelial Physiology and Pathophysiology
08:28

Experimental Models for Study of Retinal Pigment Epithelial Physiology and Pathophysiology

Published on: November 6, 2010

Expression, localization, and function of junctional adhesion molecule-C (JAM-C) in human retinal pigment epithelium

Matina Economopoulou1, Jeffrey Hammer, Fei Wang

  • 1Section for Epithelial and Retinal Physiology and Disease, National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892-2510, USA.

Investigative Ophthalmology & Visual Science
|December 9, 2008
PubMed

Insights

Junctional Adhesion Molecule C (JAM-C) is found in human retinal pigment epithelium (RPE) tight junctions, aiding in cell connection formation and granulocyte transmigration. Its knockdown disrupts RPE polarization and cell junctions.

Area of Science:

  • Ophthalmology
  • Cell Biology
  • Immunology

Background:

  • The retinal pigment epithelium (RPE) forms a critical barrier in the human eye.
  • Understanding the molecular components of RPE tight junctions is essential for barrier function and immune cell regulation.

Purpose of the Study:

  • To determine the localization of Junctional Adhesion Molecule C (JAM-C) in human RPE.
  • To characterize the functional role of JAM-C in RPE tight junction formation, cell polarization, and leukocyte transmigration.

Main Methods:

  • Immunofluorescence, Western blot, and PCR were used to analyze JAM-C, ZO-1, N-cadherin, and ezrin expression and localization in human fetal RPE (hfRPE) cell cultures and adult native RPE.
  • si-RNA mediated JAM-C knockdown was performed in hfRPE cultures.
  • A transepithelial migration assay assessed leukocyte transmigration through hfRPE monolayers.

Main Results:

  • JAM-C was localized at the tight junctions of both cultured hfRPE and adult native RPE.
  • JAM-C knockdown disrupted the organization of N-cadherin and ZO-1 at cell-cell contacts and delayed RPE cell polarization (indicated by reduced ezrin apical staining).
  • JAM-C inhibition significantly reduced granulocyte transmigration but not monocyte transmigration through the hfRPE monolayer.

Conclusions:

  • JAM-C is specifically localized in the tight junctions of human RPE (both fetal and adult).
  • JAM-C plays a crucial role in RPE tight junction formation, potentially by regulating N-cadherin and ZO-1 recruitment, and is involved in RPE cell polarization.
  • JAM-C facilitates the transmigration of granulocytes, but not monocytes, across the RPE monolayer.
Abstract

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