Abstract
Purpose::
Tetraspanins play a special role as transmembrane adaptor proteins in functional complexes with adhesion molecules and other proteins that are implicated in various cell types in the regulation of cell differentiation, proliferation, motility, and invasion. Members of this protein family have been shown to be involved in processes associated with the pathogenesis of malignant and degenerative diseases. Despite their possible importance, expression of tetraspanins in the human eye has not been studied.
Methods::
We investigated the expression of tetraspanins in the human retina and choroid by immunohistochemical staining of paraffin-embedded and immunofluorescence staining of frozen sections of donor eyes. The corresponding mRNAs were quantified in micro-dissected tissue containing the retina and the choroid by real-time RT-PCR.
Results::
Connective tissue cells of the choroid were immunostained with antibodies specific for CD9, CD81 and CD151, whereas choroidal melanocytes expressed the tetraspanins CD63 and CD81. CD151 was additionally detected in retinal and choroidal vessels. All cell types were CD82-negative. RT-PCR analyses revealed that retinal tissue contained substantial amounts of CD63 and CD81 mRNA, similar to that of mRNA encoding ß2-micorglobulin. The quantities of mRNAs specific for CD9, CD82 and CD151 were determined to be 1-2 orders of magnitude lower.
Conclusions::
The tetraspanins CD9, CD63, CD81 and CD151 are differentially expressed in different cell types of the choroid. High amounts of corresponding mRNAs suggest a significant contribution of these proteins to normal and pathogenic processes in the eye that are associated with aberrant proliferation and/or migration of cells, e.g. proliferative diabetic retinopathy and age-related macular degeneration.
Keywords: immunohistochemistry • choroid • retina