Early and late transformations occurring at organelles of the Golgi area under the influence of brefeldin A: an ultrastructural and lectin cytochemical study.
We investigated the early and late changes of the Golgi region under the influence of the fungal metabolite brefeldin A (BFA) by electron microscopy and lectin cytochemistry using the beta-galactose-specific lectin from the beetle Allomyrina dichotoma (Allo A). In control cells, Allo-A reactions were confined to trans-Golgi elements, the trans-Golgi network, and to endosomes and lysosomes; the nuclear envelope and endoplasmic reticulum were consistently free of Allo A reactions. Our findings with cells from three different lines (i.e., HepG2 hepatoma cells, WI38 fibroblasts, and L132 embryonic lung cells) showed tubular-reticular transformations of the Golgi stacks as early as 30 sec after application of BFA. The transformations started at the cis side and proceeded rapidly; after only a few minutes the Golgi apparatus was no longer apparent as an individual entity. Simultaneously, giant tubules grew out of the Golgi region and traversed the cytoplasm over micrometer-long distances. In part, they were reactive for Allo A. Reactions for beta-galactose occurred in cisternae of the endoplasmic reticulum after 4-5 min of BFA treatment; after 30 min the entire endoplasmic reticulum was intensely reactive for Allo A. At 5 min and later, the tubular-reticular transformations appeared more compact, forming glomerulus-like structures (glomerulini). These were closely associated with cisternae of the endoplasmic reticulum. Initially, glomerulini were mostly Allo A negative or showed peripheral Allo A-positive segments. The number of Allo A-positive glomerulini increased with the duration of treatment. Our findings identify the glomerulini as bipolar structures forming a link between the endoplasmic reticulum and the dissociating Golgi stacks.
Institute of Histology and Embryology, University of Innsbruck, Austria.
M
M
Pavelka
A
A
Ellinger
D020126:Brefeldin A; D002460:Cell Line; D003517:Cyclopentanes / Q000494:pharmacology*; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000648:ultrastructure; D006056:Golgi Apparatus / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D006651:Histocytochemistry; D006801:Humans; D037102:Lectins; D008854:Microscopy, Electron; D009183:Mycotoxins / Q000494:pharmacology*; D013997:Time Factors; D014407:Tumor Cells, Cultured
C045794:Allomyrina lectin; D003517:Cyclopentanes; D037102:Lectins; D009183:Mycotoxins; D020126:Brefeldin A