Figure 2.

Disruption of endocytic organelles by dynamitin overexpression. HeLa cells were transfected with dynamitin (A–H) or β-galactosidase (I and J). Transfected cells are identified by labeling with antidynamitin (C and G), anti–β-galactosidase (I), or by the characteristic dynamitin-induced fragmentation of the Golgi (A and E). A and B show double labeling for ST and TGN38, respectively. In transfected cells, one pool of TGN38 colocalizes with ST (A and B, arrows), while another shifts to the periphery (B, arrowheads). (C–F) Effect of dynamitin on TfR distribution. TfR-labeled endosomes (D and F) are lost from the juxtanuclear recycling compartment, and in some cells, they accumulate at the tips of cell processes (arrows). This peripheral distribution is only infrequently observed in untransfected cells (broad arrow, F; see also Table I). Double labeling for TfR (F) and TGN38 (E) reveals that the two markers accumulate at overlapping peripheral sites (arrows). (H and J) The distribution of LAMP-1 in dynamitin overexpressors and control transfectants, respectively. Note the extreme shift of LAMP-positive late endosomes and lysosomes into the periphery. The cell elongation shown in H was sometimes observed in dynamitin-overexpressing cells, though in HeLa cells, this effect was infrequent and was not required for maximal organelle redistribution.