Fibronectin-induced cell spreading and down-regulation of 12-lipoxygenase expression in megakaryocytic DAMI cells

During maturation of small immature megakaryocytes to mature platelet producing megakaryocytes the arachidonic acid metabolizing enzyme 12-lipoxygenase is expressed. Here we show that cells of the megakaryocytic cell line DAMI flatten and spread on fibronectin substrate in a way which may be similar to the spreading observed with bone marrow-derived megakaryocytes. The effect on DAMI cell morphology may be attributed to the RGD motif (Arg-Gly-Asp) of fibronectin. Incubation of DAMI cells with fibronectin down-regulated 12-lipoxygenase expression about 85-90%. We discuss the hypothesis that 12-HETE in megakaryocytes may act as a sensor for megakaryocyte attachment to matrix components.