Distribution of α(IV) collagen chains in the ocular anterior segments of adult mice

The distribution of the collagen chains from alpha 1(IV) to alpha 6(IV) could serve as a basis for the characterization of type IV collagen. In this study, immunohistochemistry of the ocular anterior segment of adult mice was performed using specific monoclonal antibodies against each chain in the series from alpha 1(IV) to alpha 6(IV). The results show that the components of type IV collagen in vascular basement membranes are alpha 1(IV) and alpha 2(IV) with or without alpha 5(IV) and alpha 6(IV) chains and those in epithelium and muscle basement membranes are alpha 1(IV), alpha 2(IV), alpha 5(IV), and alpha 6(IV) chains. In corneal endothelium, pigmented epithelium of iris and ciliary body, and trabecular meshwork, alpha 3(IV) and alpha 4(IV) chains are also expressed in addition to alpha 1(IV), alpha 2(IV), alpha 5(IV), and alpha 6(IV) chains. Moreover, we investigated the change in molecular composition in ciliary body during postnatal development. alpha 3(IV) and alpha 4(IV) chains were also expressed in addition to alpha 1(IV), alpha 2(IV), alpha 5(IV), and alpha 6(IV) chains in ciliary pigmented epithelium basement membrane from 7 days after birth. This result suggests that the basement membranes gradually change their biochemical features owing to temporal regulation. Taken together, these findings suggest that the different distribution and the developmental expression of alpha 1(IV) to alpha 6(IV) chains are associated with the tissue-specific function of type IV collagen in basement membranes.