EFFECT OF LAMININ ON THE NUCLEAR-LOCALIZATION OF NUCLEOLIN IN RAT INTESTINAL EPITHELIAL IEC-6 CELLS

Laminin is a major component of extracellular matrix. The mechanism of action of laminin on cell proliferation, differentiation, and migrati on is neat fully understood. In this study, we investigated the role o f extracellular matrix, especially laminin, on the cellular localizati on of the nuclear protein, nucleolin, and on cell proliferation. Immun ofluorescent and western blot analysis indicated that nucleolin was tr anslocated most efficiently to the nucleus in the small intestinal rat epithelial cell line (IEC-6) when cultured on laminin-coated plates. Specifically, nucleolin was observed predominantly in cytoplasm in the cells cultured without laminin. In contrast, nuclear localization was observed in the cells cultured on laminin. This effect of laminin on nucleolin translocation was time-dependent. Laminin was also observed to stimulate proliferation of IEC-6 cells in serum fi ee medium. Our r esults suggest that laminin alters the distribution of nucleolin which may be an early signal for cell proliferation. (C) 1998 Academic Pres s.