On the role of the nucleus in the structural organization of the cell: dispersion and rearrangement of the Golgi complex in cytoplasts treated with antimicrotubular drugs

Abstract

Using cytochemical and electron microscopic techniques, it was shown that enucleated L929 fibroblasts retained a radiating pattern of microtubules as well as a large and circumscribed Golgi complex for at least one day. At the same time, the number of ribosomes and the overall size of the rough endoplasmic reticulum were reduced, probably as a result of the arrest in production of new mRNA. Treatment of the cytoplasts with either of the microtubule-disruptive drugs colchicine or nocodazole led to loss of microtubules, aggregation of intermediate filaments in large bundles, and a characteristic disorganization of the Golgi complex with spreading of its constituent stacks of cisternae throughout the cytoplasm. After withdrawal of the drugs, microtubules reappeared, intermediate filament bundles disaggregated, and the Golgi complex resumed a morphology comparable to that of cells kept in normal medium during the entire experiment. In all these respects, the cytoplasts behaved in a similar way as nucleated cells. The observations confirm earlier notions of a role of the microtubular cytoskeleton in the organization of the Golgi complex. They further indicate that the information needed to support the normal structure and interaction of these organelle systems is present in the cytoplasm and does not require the physical presence of the nucleus, nor continuous nuclear activity, i.e. transcription and processing of mRNA.