Cytoskeletal integrity in interphase cells requires protein phosphatase activity

John Eriksson, Brautigan, Vallee, Olmsted, Fujiki, Goldman

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    Abstract

    Phosphorylation by protein kinases has been established as a key factor in the regulation of cytoskeletal structure. However, little is known about the role of protein phosphatases in cytoskeletal regulation. To assess the possible functions of protein phosphatases in this respect, we studied the effects of the phosphatase inhibitors calyculin A, okadaic acid, and dinophysistoxin 1 (35-methylokadaic acid) on BHK-21 fibroblasts. Within minutes of incubation with these inhibitors, changes are seen in the structural organization of intermediate filaments, followed by a loss of microtubules, as assayed by immunofluorescence. These changes in cytoskeletal structure are accompanied by a rapid and selective increase in vimentin phosphorylation on interphase-specific sites, and they are fully reversible after removal of calyculin A. The results indicate that there is a rapid phosphate turnover on cytoskeletal intermediate filaments and further suggest that protein phosphatases are essential for the maintenance and structural integrity of two major cytoskeletal components.
    Original languageUndefined/Unknown
    Pages (from-to)11093–11097
    JournalProceedings of the National Academy of Sciences
    Volume89
    Issue number22
    Publication statusPublished - 1992
    MoE publication typeA1 Journal article-refereed

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