Endosome Motility Research Articles

Altered movement of endosomes in colchicine-treated cultured macrophages

The effect of colchicine on the movement of phagocytic vacuoles (endosomes) has been studied by time-lapse cinemicrography and electron microscopy of cultured mouse peritoneal macrophages. In normal macrophages, ingested heat-killed E. coli are transported by independent saltatory displacements from the cell periphery to the cytocenter; in cells treated with colchicine so as to contain few intact microtubules these saltatory movements do not occur. Bacilli are incorporated and endosomes are formed essentially as in untreated cells, but endosome movement is passive. Endosome movement in colchicine-treated cells apparently results only from the flow of cytoplasm and ameboid movement induced by the drug. Changes in the distribution of acid phosphatase during phagocytosis (degranulation, appearance of diffuse enzyme staining and acid phosphatase staining of ingested bacilli) appear similar in normal and microtubule-deprived cells. Thus, microtubule-associated functions do not appear to be essential for formation of endosomes or for addition of lysosomal acid phosphatase; saltatory movements are not an obligate part of phagocytosis.