| Summary: | 碩士 === 國立成功大學 === 生理學研究所 === 89 === The interactions of extracellular matrix (ECM) and cell play important roles in cell proliferation, differentiation, and survival. Previous studies in our laboratory showed that MDCK cells lost the microvilli when cultured on type I collagen gel, whereas they formed cystic structures and exhibited microvilli formation on apical membrane when cultured in type I collagen gel. Interestingly, there was a thick layer of fibronectin deposited around MDCK cysts. We hypothesized that the property of fibronectin matrix might affect collagen fibril-induced loss of microvilli in MDCK cells. In this study, we found that total content of fibronectin and the level of assembled fibronectin matrix were enhanced in cells cultured on collagen gel-coated dish than on normal dish within 24 h. The nature of fibronectin was assessed by the treatment of the cells with collagenase. This treatment abolished collagen gel-coating induced increase in fibronectin content within one day. However, cells cultured on collagen gel-coated dish and in collagen gel exhibited markedly higher levels of collagenase-resistant fibronectin than cells cultured on normal dish and collagen gel within 2-6 days. We also detected significant increase of degraded fibronectin fragments in cells cultured on collagen gel-coated dish and in collagen gel, but the degree of fibronectin degradation seemed to be higher in the former than the latter conditions. Treatment of different fibronectin fragments also induced partial loss of microvilli in MDCK cells cultured on normal dish. In addition, rhodostomin induced disappearance of microvilli, but did not alter total content or assembled matrix of fibronectin in MDCK cells. Taken together, assembled and collagenase-resistant fibronectin matrix should be important for prevention of collagen gel-induced loss of microvilli.
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