C.Ritzenthaler*, A. Nebenführ*, A. Movafeghi*, C. Stussi-Garaud, L. Behnia, P. Pimpl, L.A. Staehelin, and D.G. Robinson (2002)
Reevaluation of the effects of brefeldin A on plant cells using tobacco BY-2 cells expressing Golgi-targeted GFP and COP I antisera.
Plant Cell, 14, 237-261.
(* denotes co-first authors)
Brefeldin A (BFA) causes a block in the secretory system of eukaryotic cells by inhibiting vesicle formation at the Golgi apparatus. Although this toxin has been used in many studies, its effects on plant cells are still shrouded in controversy. We have re-investigated the early responses of plant cells to BFA with novel tools, namely tobacco BY-2 suspension-cultured cells expressing an in vivo GFP-Golgi marker, electron microscopy of high-pressure frozen/freeze-substituted cells, as well as antisera against Atgamma-COP, a component of COPI coats, and AtArf1, the GTPase necessary for COPI coat assembly. The first effect of 10 µg mL-1 BFA on BY-2 cells is to induce in less than 5 min the complete loss of vesicle-forming Atgamma-COP from Golgi cisternae. During the following 15 to 20 min this block in Golgi-based vesicle formation leads to a series of sequential changes in Golgi architecture, the loss of distinct Golgi stacks, and the formation of an ER-Golgi hybrid compartment with stacked domains. These secondary effects appear to depend in part on stabilizing intercisternal filaments and include the continued maturation of cis and medial cisternae into trans Golgi cisternae as predicted by the cisternal progression model, the shedding of trans-Golgi network cisternae, the fusion of individual Golgi cisternae with the ER, and the formation of large ER-Golgi hybrid stacks. Prolonged exposure of the BY-2 cells to BFA leads to the transformation of the ER-Golgi hybrid compartment into a sponge-like structure that does not resemble normal ER anymore. Thus, while the primary effects of BFA on plant cells are the same as those described for mammalian cells, the secondary and tertiary effects have drastically different morphological manifestations. These results indicate that, despite a number of similarities in the trafficking machinery with other eukaryotes, there are fundamental differences in the functional architecture and properties of the plant Golgi apparatus which are the cause for the unique responses of the plant secretory pathway to BFA.
Video Sequences
The paper refers to a time-lapse video sequence of BFA effects in Golgi-GFP
cells which can be viewed here.
Another time-lapse video can be found on the Images+Videos
page.
Reprint Version
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