Deposition of nidogens and other basement membrane proteins in the young and aging mouse retina

To determine the distribution of major basement membrane constituents, particularly nidogen 1 and 2, in young and aging mouse retinae.

The specificity of antibodies against basement membrane proteins was ascertained by immunoblotting with proteins extracted from mouse retinae. The same antibodies were used in indirect immunofluorescence microscopy to localize basement membrane proteins in paraffin sections of retinae from 1-, 12- and 18-month-old C57BL/6 mice.

At a young age, laminin, perlecan and collagen IV were most abundant in Bruch's membrane. Later, the proteins were clearly detected in capillary basement membranes and the inner limiting membrane. In both of these basement membranes, a massive increase in protein amount was seen upon aging, whereas in Bruch's membrane the staining intensity was less drastically changed. Both nidogen 1 and 2 were present in vascular basement membranes and Bruch's membrane throughout the age periods studied. In the inner limiting membrane, the nidogens were more strongly expressed at higher ages, with an earlier and more extensive deposition of nidogen 1.

All major basement membrane constituents are present in the mouse retina, but the onset of deposition differs among the different proteins and between the various retinal basement membranes. In general, basement membrane protein deposition increases with age.