Type VI collagen bound to collagen fibrils by chondroitin/dermatan sulfate glycosaminoglycan in mouse corneal stroma.

We investigated the ultrastructural localization of type VI collagen in mouse corneal stroma and its relationship to striated collagen fibrils and glycosaminoglycans, using chondroitinase ABC digestion and immunoelectron microscopy with colloidal gold particles. After chondroitinase ABC digestion, the arrangement of striated collagen fibrils was disrupted, and large spaces containing widely scattered fibrils appeared. The spaces were filled by filamentous networks that were stained by anti-type VI collagen IgG, which were apparently clumps of beaded filament. Interfibrillar type VI collagen beaded filaments and immunogold particles decreased. Our results indicate that type VI collagen is bound to the striated collagen fibrils by mediation of chrondroitin/dermatan sulfate glycosaminoglycan or proteoglycan. We believe that this interaction is essential to the orderly arrangement of the striated collagen fibrils, which results in corneal transparency.