Dataset Information

Reorganization of the microtubule array in prophase/prometaphase requires cytoplasmic dynein-dependent microtubule transport.

ABSTRACT: When mammalian somatic cells enter mitosis, a fundamental reorganization of the Mt cytoskeleton occurs that is characterized by the loss of the extensive interphase Mt array and the formation of a bipolar mitotic spindle. Microtubules in cells stably expressing GFP-alpha-tubulin were directly observed from prophase to just after nuclear envelope breakdown (NEBD) in early prometaphase. Our results demonstrate a transient stimulation of individual Mt dynamic turnover and the formation and inward motion of microtubule bundles in these cells. Motion of microtubule bundles was inhibited after antibody-mediated inhibition of cytoplasmic dynein/dynactin, but was not inhibited after inhibition of the kinesin-related motor Eg5 or myosin II. In metaphase cells, assembly of small foci of Mts was detected at sites distant from the spindle; these Mts were also moved inward. We propose that cytoplasmic dynein-dependent inward motion of Mts functions to remove Mts from the cytoplasm at prophase and from the peripheral cytoplasm through metaphase. The data demonstrate that dynamic astral Mts search the cytoplasm for other Mts, as well as chromosomes, in mitotic cells.

SUBMITTER: Rusan NM

PROVIDER: S-EPMC2173209 | biostudies-literature | 2002 Sep

REPOSITORIES: biostudies-literature

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Reorganization of the microtubule array in prophase/prometaphase requires cytoplasmic dynein-dependent microtubule transport.

Rusan Nasser M NM Tulu U Serdar US Fagerstrom Carey C Wadsworth Patricia P

The Journal of cell biology 20020916 6

When mammalian somatic cells enter mitosis, a fundamental reorganization of the Mt cytoskeleton occurs that is characterized by the loss of the extensive interphase Mt array and the formation of a bipolar mitotic spindle. Microtubules in cells stably expressing GFP-alpha-tubulin were directly observed from prophase to just after nuclear envelope breakdown (NEBD) in early prometaphase. Our results demonstrate a transient stimulation of individual Mt dynamic turnover and the formation and inward m ...[more]

PMID: 12235119

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Project description:This study compares the role of electrostatics in the binding process between microtubules and two dynein microtubule-binding domains (MTBDs): cytoplasmic and axonemal. These two dyneins are distinctively different in terms of their functionalities: cytoplasmic dynein is processive, while axonemal dynein is involved in beating. In both cases, the binding requires frequent association/disassociation between the microtubule and MTBD, and involves highly negatively charged microtubules, including non-structured C-terminal domains (E-hooks), and an MTBD interface that is positively charged. This indicates that electrostatics play an important role in the association process. Here, we show that the cytoplasmic MTBD binds electrostatically tighter to microtubules than to the axonemal MTBD, but the axonemal MTBD experiences interactions with microtubule E-hooks at longer distances compared with the cytoplasmic MTBD. This allows the axonemal MTBD to be weakly bound to the microtubule, while at the same time acting onto the microtubule via the flexible E-hooks, even at MTBD?microtubule distances of 45 Å. In part, this is due to the charge distribution of MTBDs: in the cytoplasmic MTBD, the positive charges are concentrated at the binding interface with the microtubule, while in the axonemal MTBD, they are more distributed over the entire structure, allowing E-hooks to interact at longer distances. The dissimilarities of electrostatics in the cases of axonemal and cytoplasmic MTBDs were found not to result in a difference in conformational dynamics on MTBDs, while causing differences in the conformational states of E-hooks. The E-hooks' conformations in the presence of the axonemal MTBD were less restricted than in the presence of the cytoplasmic MTBD. In parallel with the differences, the common effect was found that the structural fluctuations of MTBDs decrease as either the number of contacts with E-hooks increases or the distance to the microtubule decreases.

Dataset Information

Reorganization of the microtubule array in prophase/prometaphase requires cytoplasmic dynein-dependent microtubule transport.

Publications

Reorganization of the microtubule array in prophase/prometaphase requires cytoplasmic dynein-dependent microtubule transport.

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