Structure and Function of the Core Protein of Fibronectin-binding Proteoglycan

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Followings are new findings from the studies on a fibronectin-binding proteoglycan which we have newly found in the human term placenta. 1. The study of the interaction between the proteoglycan and the thermolysin fragments of fibronectin has indicated that the proteoglycan binds fibronectin via a gelatin-binding domain. 2. The proteoglycan has no activity promoting adhesion and spreading of FL amnion cells on plastic dishes, but it does promote cell-spreading of these cells, if the proteoglycan has been bound to the fibronectin-coated dishes. These cells show good adhesion onto the fibronectin-coated dishes, but they do not spread well without the proteolycan bound to fibronectin. These data suggest that the cell activities can be affected differently by a combination of extracellular matrix components. 3. Immunohistochemical studies on basement membrane components including the proteoglycan of squamous cell carcinoma have suggested that poorly differentiated tumors tend to have highly degraded basement membranes which may reflect a greater proteolytic activity than that in the well differentiated tumors. In some cases, the proteoglycan is detectable in the tumor stroma in association with fibronectin, suggesting that the binding between fibronectin and the proteoglycan does occur in vivo. The determination of the core protein structure by the analysis of cDNA would be useful to elucidate the biological function of this proteoglycan.