Phorbol myristate acetate stimulates microtubule and 10-nm filament extension and lysosome redistribution in mouse macrophages

Abstract

Phorbol myristate acetate (PMA) stimulates cell spreading and fluid-phase pinocy-tosis in mouse peritoneal macrophages. Colchicine (10-4 M) and cytochalasin B (10-7 M) abolish PMA stimulated pinocytosis but have little effect on cellular spreading (Phaire-Washington et al., 1980, j. Cell Biol., 86:634-640). We report here that PMA also alters the organization of the cytoskeleton and the distribution of organelles in these cells. Neither control nor PMA-treated macrophages contain actin cables. PMA-treated resident and thioglycolate-elicited macrophages exhibit beneath their substrate-adherent membranes many randomly distributed punctate foci that stain brightly for actin. The appearance and distribution of these actin-containing foci are not altered by colchicine (10-4M) or cytochalasin B (10-8 M). In thioglycolate-elicited macrophages PMA causes the extension and radial organization of microtubules and 10-nm filaments and promotes the movement of secondary lysosomes from their perinuclear location to the peripheral cytoplasm. Depending upon the concentration of PMA used, 45-71% of thioglycolate-elicited macrophages and 32-44% of proteose-peptone-elicited macrophages and numerous lysosomes, radiating from the centrosphere region, arranged linearly along microtubule and 10-nm filament bundles. Colchicine (10-7 M) and podophyllotoxin (10-7 M) prevent the radial redistribution of microtubules, 10nm filaments, and lysosomes in these cells. Cytochalasins B and D (10-8 M) have no inhibitory effects on these processes. These findings indicate that microtubules and 10-nm filaments respond in a coordinated fashion to PMA and to agents that inhibit microtubule function; they suggest that these cytoskeletal elements regulate the movement and distribution of lysosomes in the macrophage cytoplasm. © 1980, Rockefeller University Press., All rights reserved.