Characterization of a type VI collagen-related Mr-140 000 protein from cutis-laxa fibroblasts in culture

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Abstract
The precise biochemical defects in connective-tissue metabolism that are responsible for the laxity of skin seen in the syndrome of cutis laxa are largely unknown. Fibroblasts cultured from skin explants of a 2-yr-old male with the syndrome were studied. EM examination of this skin revealed decreased amounts of amorphous elastin and an increase in elastin-associated microfibrils. Although the cultured fibroblasts were similar to control skin fibroblasts in morphology, growth rate and total protein synthesis, there was a 4- to 6-fold increase in accumulation of a collagenous protein of MW 140,000 in both the culture medium and in the cell layer. This protein was structurally distinct from collagen types I, III, IV, V and VIII. It was related to a cell-surface-associated glycoprotein, GP140, by both antigenic cross-reactivity and peptide mapping. GP140 evidently is a precursor of at least one form of pepsin-extracted type VI collagen.