Caveolin-1 Localization in Müller Cells of the Retina

Abstract

Novel caveolae proteins, caveolins, were found about a decade ago, and many new aspects of caveolae functions have since been uncovered. However, it remains elusive how caveolins function in ocular tissues, so we would like to address this issue. We conducted experiments in vivo and in vitro with immunohisto/cytochemistry and immunoblot. In vivo immunohistochemistry showed that caveolin-1 was expressed in Müller cells and corneal endothelial cells of the rat retina. Confocal double-labeling images demonstrated that caveolin-1 was co-localized with L-glutamate/L-aspartate transporter (GLAST) and glutamine synthetase (GS), confirming that caveolin-1 is expressed in Müller cells. With in vitro experiments, immunoblotting showed that cultured Müller cells express caveolin-1 and -2 but not -3, and immunocytochemistry demonstrated that caveolin-1 and -2 are differently localized in Müller cells. Moreover, caveolin-1 is exclusively co-localized with GLAST but not with GS in cultured Müller cells. These results indicate the possibility that caveolin-1 may be associated with glutamate metabolism in the retina through Müller cells.