Abstract
Purpose: :
Tight junctions (TJs) are important components of the blood-retinal barrier. However, the evidence for the presence of tight junction-associated proteins in human retina is lacking. To understand the contribution of each claudin subtype to TJ formation in the inner blood-retinal barrier of human eye, the expression and distribution of claudin subtypes in adult human retina were investigated in this study.
Methods: :
Eye balls of healthy adult individuals were obtained from the Eye Bank of Zhongshan Ophthalmic Center. Whole retinas were dissected carefully. RT-PCR was used to assess mRNA expression of claudins in normal adult human retinas. Western blot analysis and immunofluorescence staining were performed to determine the protein expression and tissue distribution of selected claudins respectively.
Results: :
RT-PCR showed that claudin-12 was the most abundant subtype, followed by claudin-1, -2, -3, -4, -5 and -22. Claudin-6 to -11, -14 to -19 and -23 were not detected at mRNA level. Expression of claudin-1, -2, -3, -4 and -5 were identified in the retinas by western blot. By immunofluorescence staining, claudin-1, -2, -3 and -5 were found to be localized on retinal microvessels.
Conclusions: :
This study indicates that claudin-1, -2, -3, -4 and -5 are expressed on the retinal vessels in the normal adult human retinas. These claudins may be responsible for maintaining the normal function of inner blood-retinal barrier.
Keywords: retina • cell adhesions/cell junctions • vascular occlusion/vascular occlusive disease