p34cdc2-mediated phosphorylation mobilizes microtubule-organizing centers from the apical intermediate filament scaffold in CACO-2 epithelial cells

Yolanda Figueroa, Flavia A. Wald, Pedro J Salas

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We have shown previously that centrosomes and other microtubule-organizing centers (MTOCs) attach to the apical intermediate filament (IF) network in CACO-2 cells. In this cell line, intermediate filaments do not disorganize during mitosis. Therefore, we speculated that the trigger of the G2-M boundary may also detach MTOCs from their IF anchor. If that was the case, at least one of the proteins involved in the attachment must be phosphorylated by p34cdc2 (cdk1). Using confocal microscopy and standard biochemical analysis, we found that p34cdc2-mediated phosphorylation indeed released MTOCs from IFs in permeabilized cells. In isolated, immunoprecipitated multiprotein complexes containing both γ-tubulin and cytokeratin 19, p34cdc2 phosphorylated only one protein, and phosphorylation released cytokeratin 19 from the complexes. We conclude that this as yet unidentified protein is a part of the molecular mechanism that attaches MTOCs to IFs in interphase.

Original languageEnglish
Pages (from-to)37848-37854
Number of pages7
JournalJournal of Biological Chemistry
Issue number40
StatePublished - Oct 4 2002


ASJC Scopus subject areas

  • Biochemistry

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