CELLULAR CONTRACTION OF COLLAGEN LATTICES IS INHIBITED BY NONENZYMATIC GLYCATION

High glucose concentrations associated with diabetes have been shown t o cause the nonenzymatic modification of proteins, Reducing sugars cov alently bind to free amine groups, undergo Amadori rearrangements, and crosslink with other glucose-modified proteins, Crosslinking of type I collagen by incubation with different concentrations of glucose 6-ph osphate for up to 5 days resulted in a nondeformable collagen lattice as assayed by physical compaction analysis, Nonglycated collagen was f ully compactible, Fibroblasts cultured on nonglycated collagen lattice s were able to contract the lattice over a 5-day period, while fibrobl asts on collagen glycated with 50 mM Or more glucose 6-phosphate were unable to do this. Cells on both nonglycated and glycated collagen lat tices initially lacked organized bundles of actin microfilaments or st ress fibers, Over time, the cells on glycated lattices formed stress f ibers, suggesting that they were still exerting mechanical force on a nondeformable matrix. These results suggest that crosslinking of colla gen fibrils by nonenzymatic glycation alters the physical properties o f the extracellular matrix, resulting in changes in the organization o f the intracellular actin cytoskeleton. (C) 1996 Academic Press, Inc.