Inositol 1,4,5-trisphosphate concentrations increase after adherence in the macrophage-like cell line J774.1. |
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| Authors: | V Zabrenetzky and E K Gallin |
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| Affiliation: | Department of Physiology, Armed Forces Radiobiology Research Institute, Bethesda, MD 20814-5145. |
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| Abstract: | 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. Inositol mono- and bis-phosphate concentrations were also elevated 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 Ca2+-free medium. However, doubling intracellular Ca2+] by addition of the Ca2+ ionophore ionomycin (1 microM) 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. |
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