alphaB-crystallin interacts with cytoplasmic intermediate filament bundles during mitosis.
The small heat-shock protein alphaB-crystallin interacts with intermediate filament proteins. Using cosedimentation assay, we showed previously that in vitro binding of alphaB-crystallin to peripherin and vimentin was temperature-dependent. Furthermore, when NIH 3T3 cells were submitted to different stress conditions a dynamic reorganization of the intermediate filament network was observed concomitantly with the recruitment of alphaB-crystallins on the intermediate filament proteins. Thus, the intracellular state of alphaB-crystallin correlated directly with the remodeling of the intermediate filament network in response to stress. Here, we show data suggesting that alphaB-crystallin is implicated in remodeling of intermediate filaments during cell division. We investigated the intracellular distribution of alphaB-crystallin in naturally occurring mitotic NIH 3T3 cells and in neuroblastoma N2a and N1E115 cells. In NIH 3T3 cells, alphaB-crystallin remained diffused throughout the cell cycle. Subcellular fractionation of alphaB-crystallin showed that alphaB-crystallin remained in the cytosolic compartment during mitosis. Furthermore, alphaB-crystallin accumulated in mitotically arrested NIH 3T3 cells. This increased level of alphaB-crystallin protein was due to an increased level of alphaB-crystallin mRNA in mitotic NIH 3T3 cells. In the neuroblastoma cells, the intermediate filaments were rearranged into thick cable-like structures and alphaB-crystallin was recruited onto them. In neuroblastoma N2a cells the level of expression did not change during the cell cycle. However, a small fraction of alphaB-crystallin switched onto the insoluble fraction in mitotically arrested N2a cells. Our results suggested that depending on the state of rearrangement of the intermediate filament network during mitosis alphaB-crystallin was either recruited onto the intermediate filaments or upregulated in the cytosolic compartment.
Djabali
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Cytosquelette et Développement, Pitié-Salpêtrière, CNRS-URA 2115, 105 Boulevard de l'Hôpital, Paris Cedex 13, 75634, France. djabali@dodo.cpmc.columbia.edu
Piron
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G
de Néchaud
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Portier
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MM
D016475:3T3 Cells; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D018833:Chaperonins / Q000032:analysis / Q000378:metabolism; D003459:Crystallins / Q000032:analysis / Q000378:metabolism*; D003593:Cytoplasm / Q000737:chemistry / Q000378:metabolism*; D019084:Fluorescent Antibody Technique, Indirect; D007382:Intermediate Filaments / Q000502:physiology*; D007399:Interphase / Q000502:physiology; D051379:Mice; D008938:Mitosis / Q000502:physiology*; D009447:Neuroblastoma; D015739:Nocodazole / Q000494:pharmacology; D013347:Subcellular Fractions / Q000737:chemistry; D014407:Tumor Cells, Cultured; D014746:Vimentin / Q000032:analysis / Q000378:metabolism
D000970:Antineoplastic Agents; D003459:Crystallins; D014746:Vimentin; D018833:Chaperonins; D015739:Nocodazole