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Updated: Jul 27, 2026
Experimental Models for Study of Retinal Pigment Epithelial Physiology and Pathophysiology
Published on: November 6, 2010
Claudin 5 is transiently expressed during the development of the retinal pigment epithelium
1Department of Surgery, Yale University School of Medicine, P.O. Box 208062 New Haven, CT, 06520-8062, USA.
Insights
Chick retinal pigment epithelium (RPE) tight junction selectivity increases during development, driven by transient claudin 5 expression. Neural retina factors upregulate claudin 5 early in RPE development.
Area of Science:
- Developmental biology
- Cell biology
- Ophthalmology
Background:
- Tight junctions in the retinal pigment epithelium (RPE) regulate barrier function.
- Claudins are key transmembrane proteins forming tight junction strands and determining selectivity.
- RPE development involves dynamic changes in barrier permeability and selectivity.
Purpose of the Study:
- To investigate the role of claudins in chick RPE development.
- To characterize the expression patterns of claudins 3 and 5 during RPE development.
- To determine the influence of neural retina on claudin expression in RPE.
Main Methods:
- Reverse transcriptase-polymerase chain reaction (RT-PCR) for gene sequencing and expression analysis.
- Northern blotting to detect claudin mRNA expression.
- Immunoblotting to assess protein levels.
- Primary RPE cell culture to study regulatory factors.
Main Results:
- Claudin 5 is expressed in chick RPE, while claudin 3 is found in the choroid.
- Claudin 5 expression is transient, peaking between embryonic days 10-14.
- Neural retina-secreted factors significantly upregulate claudin 5 expression in early-stage RPE.
- Claudin 5 expression correlates with intermediate RPE development stages but is replaced later.
Conclusions:
- Claudin 5 plays a crucial role in mediating selectivity during chick RPE development.
- Neural retina signaling regulates claudin 5 expression, impacting RPE barrier function.
- Dynamic changes in claudin expression, including the replacement of claudin 5, underlie late-stage RPE maturation and altered selectivity.
Abstract:
During the development of chick retinal pigment epithelium (RPE), the permeability and selectivity of the epithelium's tight junctions are continuously modulated. Overall paracellular permeability decreases, but selectivity increases. Because the claudin family of transmembrane proteins appears to provide the structural basis for selectivity, we examined the expression of claudins as a function of development in chick RPE. Degenerate primers were used with the reverse transcriptase-polymerase chain reaction (RT-PCR) to obtain complete sequences of chick claudins 3 and 5. Northern blotting and semi-quantitative RT-PCR demonstrated that claudin 5 was expressed in RPE, but claudin 3 was expressed only in the choroid layer of the eye. Northern blotting, semiquantitative RT-PCR and immunoblotting demonstrated that the expression of claudin 5 was transient, with peak levels of expression between embryonic days 10 and 14. Primary cultures were used to demonstrate that factors secreted by the neural retina induced the expression of claudin 5 nearly 3-fold if RPE was isolated from embryonic day 7 embryos. There was little effect if RPE was isolated from embryonic day 14. The upregulation of claudin 5 correlates with permeability changes that occur during the intermediate stage of RPE development. Interestingly, claudin 5 must be replaced during the late stage of development when the number and complexity of tight junctional strands increases. This would imply more changes in selectivity.
