Inositol 1,4,5-trisphosphate Concentrations Increase after Adherence in the Macrophage-Like Cell Line J774.1

摘要

The migration of macrophages to areas of chronic inflammation and infection involves adherence to a variety of surfaces. Several properties of macrophages change when suspended cells become adherent. To determine the intracellular signals involved in these changes, concentrations of the second messenger inositol 1,4,5- trisphosphate Ins(1,4,5)P3 were monitored during adherence of J774.1 cells, a macrophage-like cell line. When cells grown in suspension were allowed to adhere to a glass surface, there was a transient increase in InsP3 that reached a peak between 100 and 120 s after plating. Analysis of isomer distribution showed significant 3-fold increases in Ins(1,4,5)P3 and inositol 1,3,4,5-tetrakisphosphate Ins(1,3,4,5)P4 at 100 s after plating. These values were maintained at 120 s with the additional appearance of a 4-fold increase in inositol 1,3,4-trisphosphate. The adherence-induced generation of Ins(1,4,5)P3 was decreased, and Ins (1,3,4,5)P4 formation was blocked, in calcium ion free medium. However, doubling intracellular Ca 2+ by addition of the Ca 2+ ionophore ionomycin did not increase Ins(1,4,5)P3 in suspended cells. Adherence of J774.1 cells to fibronectin-coated glass also induced an increase in InsP3. Reprints. (aw)