Dynamin 2 has been reported to be implicated in phagocytosis. However, the mode of action of dynamin is Poorly understood. In this Study, we examined whether dynamin 2 participates in actin assembly during phagocytosis in Sertoli cells. In the presence of dynasore, a dynamin inhibitor, phagocytosis was reduced by 60-70% in Sertoli cells and macrophages. Scanning electron microscopy revealed that Sertoli cells treated with dynasore were unable to form phagocytic cups. In addition, dysfunction of dynamin 2 reduced both actin polymerization and recruitment of actin and dynamin 2 to phosphatidylinositol (4,5) bisphosphate [ PI(4,5)P-2]-containing liposomes. The formation of dynamin 2-positive ruffles of Sertoli cells was decreased by 60-70% by sequestering PI(4,5)P2 either by expression of PH domain of PLC delta or treatment with neomycin. These results strongly Suggest that dynamin 2 is involved in actin dynamics and the formation of dynamin 2-positive ruffles during phagocytosis. (C) 2008 Elsevier Inc. All rights reserved.