Decorin binds to collagen fibrils in human skin and inhibits MMP1 mediated collagen fibril cleavage.

(A) Biopsies from normal buttock skin and collagen lattices containing decorin were stained with cupromeronic blue and analyzed by transmission electron microscopy. Electron micrographs revealed that decorin binds to the surface of collagen fibrils in human skin in vivo and in collagen lattices. Micrograph of human skin section without cupromeronic blue staining is included as negative control for decorin staining. Micrograph of non-stained control shows three cross-sectioned collagen fibrils displayed as white circles and indicated by arrows, and a longitudinal-sectioned collagen fibril displayed as a white filament. In micrographs of stained skin, decorin appears as small black filaments or solid black spheres (white arrow heads) that are localized on the surface of longitudinal-sectioned collagen fibrils. Micrograph of collagen lattices shows decorin (white arrow heads) associated with longitudinal-sectioned and cross-sectioned collagen fibrils. The schematic drawing shows decorin core proteins (solid black ellipses) and GAG chains (black lines) intertwine with a collagen fibril in a cross-section view. (B) Collagen lattices with or without decorin were treated with MMP-1. Collagen fragmentation was analyzed by SDS-PAGE eletrophoresis followed by Coomassie blue staining. Collagen fragments were quantified using ImageQuant software. Results are mean ± SEM (N = 3; *p<0.01). Inset shows a representative gel.