Distinct effects of different matrix proteoglycans on collagen fibrillogenesis and cell-mediated collagen reorganization

The extracellular matrix (ECM) is a complex mixture composed of fibrillar collagens as well as additional protein and carbohydrate components. Proteoglycans (PGs) contribute to the heterogeneity of the ECM and play an important role in its structure and function. While the small leucine rich proteoglycans (SLRPs), including decorin and lumican, have been studied extensively as mediators of collagen fibrillogenesis and organization, the function of large matrix PGs in collagen matrices is less well known. In this study, we showed that different matrix PGs have distinct roles in regulating collagen behaviors. We found that versican, a large chondroitin sulfate PG, promotes collagen fibrillogenesis in a turbidity assay and upregulates cell-mediated collagen compaction and reorganization, whereas aggrecan, a structurally-similar large PG, has different and often opposing effects on collagen. Compared to versican, decorin and lumican also have distinct functions in regulating collagen behaviors. The different ways in which matrix PGs interact with collagen have important implications for understanding the role of the ECM in diseases such as fibrosis and cancer, and suggest that matrix PGs are potential therapeutic targets. HighlightsO_LISmall leucine rich proteoglycans (SLRPs) and large chondroitin sulfate (CS) proteoglycans (PGs) have distinct effects on collagen fibrous network behavior. C_LIO_LIUnlike other matrix proteoglycans, versican promotes collagen fibrillogenesis in an in vitro spectrophotometric (turbidity) assay. C_LIO_LIThe versican core protein has a larger impact on collagen behavior in a fibrillogenesis assay than its glycosaminoglycan chains do. C_LIO_LIVersican increases the diameter of collagen fibers and the porosity of collagen fibrous networks, unlike aggrecan and SLRPs. C_LIO_LIThe addition of versican to collagen does not alter fibroblast contractility but leads to enhanced cell-mediated collagen reorganization and contraction. C_LI