The NDR family kinase NdrA of Dictyostelium localizes to the centrosome and is required for efficient phagocytosis.

ABSTRACT

Dictyostelium discoideum cells are professional phagocytes that provide an easily accessible system to gain insights into the mechanisms and the regulatory machinery controlling phagocytosis. Here, we describe a novel function for nuclear Dbf2-related (NDR) family kinases in phagocytosis of D. discoideum. Deletion of one of the four NDR kinases of D. discoideum, NdrA, resulted in impaired cell growth caused by reduced phagocytosis rates. Detailed analysis of NdrA-null cells revealed that the formation of phagocytic cups was delayed. Microscopic investigations showed that NdrA localizes to centrosomes, and NdrA was also identified in isolated centrosome preparations. The localization of NdrA is regulated during the cell cycle. In prophase, NdrA disappears from the centrosome and forms a cloud-like structure around the spindle, which is totally absent during later stages until completion of mitosis. Our results suggest that a signal which originates from the NdrA kinase at the centrosome affects the efficiency of phagocytosis. We assume that in NdrA-null cells the defects in phagocytosis may be caused by an impairment of vesicle trafficking, which is involved in providing new membrane at the sites of particle uptake.