DIRECT OBSERVATION OF HEXOKINASE TRANSLOCATION IN STIMULATED MACROPHAGES

1. Fluorescence imaging of antibodies was used to show that phorbol 12 -myristate 13-acetate (PMA) induces a 4-fold increase in the amount of hexokinase relative to the control in the cortical shell of rat perit oneal macrophage cytosol adjacent to the plasma membrane, and a corres ponding depletion in the amount of hexokinase in the central core of t he cytosol. However, there was no significant PMA-dependent change in the distribution of glucose-6-phosphate dehydrogenase. 2. Cytochalasin D, an inhibitor of actin microfilament polymerization, prevented the PMA-induced hexokinase translocation and also reduced the PMA-dependen t increases in 2-deoxy-D-glucose transport and glucose-dependent PMA-s timulated superoxide production. 3. PMA caused a contraction of the wi dth of the cortical F-actin zone. Cytochalasin D caused some dispersal of F-actin within the cell, increasing the density of F-actin within the central cytosolic core and causing aggregation of the F-actin with in the cortex. These data are consistent with the view that PMA induce s attachment of hexokinase to microfilaments within the cortical zone adjacent to the cell membrane of macrophages, and cytochalasin D preve nts this attachment. This is the first direct demonstration of the tra nslocation of hexokinase to the plasma membrane in activated cells, an d supports the view that enhanced hexokinase activity in the cortical region of the cytosol is an important early component of the macrophag e activation process.