Influence of cytoskeletal assembly on phosphatidylcholine synthesis in intact phagocytic cells

Interactions of the plasma membrane with the cytoskeleton are required for diverse cellular functions such as adhesion, division, secretion, endocytosis and chemotaxis. We therefore investigated whether the reversible assembly of microtubules and/or microfilaments in leukocytes affected the synthesis of a key membrane component, phosphatidylcholine. The effects of a variety of antitubuin and antimicrofilament agents on phosphatidylcholine synthesis via the methylation of phosphatidyl-ethanolamine and its formation through CDP-choline were studied. The antitubulins inhibited the incorporation of 3H-methyl groups into phosphatidylethanolamine in guinea pig macrophages and polymorphonuclear leukocytes by as much as 64%, while cytochalasin B, an antimicrofilament agent, had no effect. In contrast, the incorporation of methyl-3H-choline into phosphatidylcholine was stimulated in these cells by as much as 2 fold by the anti-tubulins. The synthesis of phosphatidylcholine in a nonphagocytic cell type, splenic lymphocytes, was not altered in the presence of the antitubulin agents. Changes in the state of polymerization of cellular tubulin pools associated with certain specialized functions of cells may, through effects on phosphatidylcholine synthesis, alter local membrane composition, microviscosity, or the interaction of membrane proteins with their environment.