Depletion of protein phosphatase 4 in human cells reveals essential roles in centrosome maturation, cell migration and the regulation of Rho GTPases

Cristina Martin-Granados, Amanda Philp, Senga K. Oxenham, Alan R. Prescott, Patricia T. W. Cohen

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    27 Citations (Scopus)

    Abstract

    The mechanisms that co-ordinate centrosome maturation and the migration of human cells remain elusive. Protein phosphatase 4 (Ppp4) is a ubiquitous protein serine/threonine phosphatase in eukaryotes that is enriched at centrosomes. HEK293 cells cultures depleted to 30% Ppp4c levels by lentivirus-delivered stable gene silencing were delayed in mitosis at the prometaphase/metaphase boundary and displayed cells with aberrant chromosome organisation and microtubules unconnected to the centrosomes. The levels of alpha- and gamma-tubulin and aurora A were decreased; in mitotic cells, the cytological localisations of polo-like kinase 1, alpha- and gamma-tubulin and aurora A were aberrant and the phosphorylation of Aurora A-Thr 288 was decreased. The novel localisation of endogenous Ppp4 regulatory subunit, R3A, to centrosomes in human mitotic cells suggests that a Ppp4c-R2-R3 trimeric complex mediates centrosome maturation. We demonstrate for the first time that human cells depleted to 30% Ppp4c showed severely decreased migration and exhibit decreased levels of both total beta-actin and filamentous actin in cell extensions, filopodia and lamellopodia-like structures. Our studies show that Ppp4c is required for the organisation of the actin cytoskeleton at the leading edge of human cells during migration. We also demonstrate that the active forms of the RhoGTPases, Rac1 and Cdc42, are substantially decreased in the presence and absence of growth factor in Ppp4c depleted cells, implicating Ppp4c in the regulation of these GTPases. The results suggest that Ppp4c-R2-R3 complexes may co-ordinate centrosome maturation and cell migration via regulation of RhoGTPases and that Ppp4 may be a useful anticancer target. Crown Copyright (c) 2008 Published by Elsevier Ltd. All rights reserved.

    Original languageEnglish
    Pages (from-to)2315-2332
    Number of pages18
    JournalInternational Journal of Biochemistry & Cell Biology
    Volume40
    Issue number10
    DOIs
    Publication statusPublished - 2008

    Keywords

    • protein phosphatase 4
    • centrosome maturation
    • cell migration
    • Aurora A
    • Rho GTPase
    • PROTEIN PHOSPHATASE 4
    • HISTONE H3 PHOSPHORYLATION
    • AURORA-A
    • CHROMOSOME SEGREGATION
    • CAENORHABDITIS-ELEGANS
    • CONSERVED PROTEIN
    • GAMMA-TUBULIN
    • HELA-CELLS
    • DROSOPHILA
    • KINASE

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