Glycosaminoglycan and collagen fibrillar interactions in the mouse corneal stroma

When sections of mouse corneal stroma were treated with 20 mM adenosine 5'-triphosphate (ATP) in phosphate buffered saline, pH 4.0, at 37 degrees C and observed by electron microscopy, numerous periodic fibrils with about 100-nm periodicity appeared which were the aggregated form of type VI collagen (type VI collagen fibrils). They occurred in close association with D-periodic fibrillar collagens (striated collagen fibrils). However, when the tissue was digested with chondroitinase ABC or testicular hyaluronidase prior to the ATP treatment, type IV collagen fibrils were segregated from striated collagen fibrils, even though the type VI collagen fibrils themselves aggregated to form the 100 nm-periodic structures. Keratanase or Streptomyces hyaluronidase had no such effect. One possible suggestion is that the ATP-aggregated type VI collagen fibrils are connected with striated collagen fibrils through chondroitin/dermatan sulfate glycosaminoglycans.