Different caveolin isoforms in the retina of melanoma malignum affected human eye

Abstract

Purpose: Caveolin-1 has been identified in Müller and pigment cells of rodents, but the distribution of caveolin isoforms has not been studied in the human retina. Since there are no relevant data in humans, we aimed to study the distribution of caveolins in the human retina.

Methods: Our samples were derived from eyes affected by melanoma malignum choroideae that were enucleated. The distribution of the caveolins was examined by immunocytochemistry using isoform-specific antibodies.

Results: In this study we report on the presence of different caveolin isoforms in many cell types of the human retina. These isoforms were present in several regions and layers in the human retina. Centro-peripheral changes have been detected: the distribution altered following the radier direction.

Conclusions: This is the first demonstration of caveolin expression in the human retina. Our data suggest that caveolins play an important role in the function of retinal cells. Our observations refute previous assumptions that there is a shortage of caveolins in the retina. Since the retina contains a number of different neuronal and glial cell types, the caveolin expression of these cells can no longer be a matter of dispute.

Figure 1

Immunocytochemical analysis of caveolin-1 in the human retina. Samples were taken from different sites the retina following a radial plane from the central to the peripheral retina. A, D, F: Macular region, M. B, E, G: Periphery, P. C: ciliary body, CB. Alexa Fluor 488 was used to detect caveolin-1 (green). The cytoskeleton and the nuclei were treated with Alexa fluor 594 labeled phalloidin (red) and DAPI (blue), respectively. Merged images are presented. Caveolin-1 was present in all layers of the retina. Weakest signals could be seen in the pigment epithelium (low A). The different regions showed a center-to-peripheral gradient; increasing from very low, low, moderate and high density (M, A, D, F), reaching the maximum level (very high; P, B, E, G), then decreasing towards the extreme periphery of the retina (very low, low; CB, C). Pigment granules showed autofluorescence, but they could be distinguished from caveolin signals. Scale bar represents 10 μm. The following abbreviations were used: pigment epithelium (PE), outer segments (OS), outer limiting membrane (OLM), outer nuclear layer (ONL), outer plexiform layer (OPL), inner nuclear layer (IPL), inner plexiform layer (INL), ganglion cells (GC), optic nerve fibers (ONF), inner limiting membrane (ILM).

Figure 2

Immunocytochemical analysis of caveolin-2 in the human retina. Samples were taken as described in Figure 1. Alexa Fluor 488 was used to detect caveolin-2 (green). The cytoskeleton and the nuclei were treated with Alexa fluor 594 labeled phalloidin (red) and DAPI (blue), respectively. Merged images are shown. Caveolin-2 was found in the outer nuclear layer (ONL) and the inner limiting membrane (ILM), including the intervening layers. A, D, and F reveal: very low, low, and moderate densities (M). B, E: At the peripheral part (P) immunoreactivities (IRs) were observed only in the outer nuclear layer (ONL), outer plexiform layer (OPL), inner nuclear layer (INL), and ganglion cell (GC; very low, low). C: No signals were observed at the epithelium of the ciliary body (CB). Note, that pigment granules show autofluorescence. Scale bar represents 10 μm. The following abbreviations used in this figure: pigment epithelium (PE), outer segments (OS), outer limiting membrane (OLM), inner nuclear layer (IPL), optic nerve fibers (ONF).

Figure 3

Immunocytochemical analysis of caveolin-3 in the human retina. Samples were taken as described in Figure 1. Alexa Fluor 488 was used to detect caveolin-3 (green). The cytoskeleton and the nuclei were treated with Alexa fluor 594 labeled phalloidin (red) and DAPI (blue), respectively. Presented images are merged. Caveolin-3 was observed in the outer nuclear layer (ONL) and the inner limiting membrane (ILM), including the intervening layers. A, D, and F: show very low, low, and moderate densities (M). B, E, G: At the peripheral part (P) IRs also occurred in the layer of the outer segments (low). C: At the ciliary body (CB), caveolin-3 signals could be seen in both layers (low, moderate). Note, that pigment granules show autofluorescence. Scale bar represents 10 μm. Following abbreviations are used in this figure: outer segments (OS), outer limiting membrane (OLM), outer plexiform layer (OPL), inner nuclear layer (IPL), inner plexiform layer (INL), ganglion cells (GC), optic nerve fibers (ONF).