Phosphorylation on Ser5 increases the F-actin-binding activity of L-plastin and promotes its targeting to sites of actin assembly in cells

Bassam Janji, Adeline Giganti, Veerle De Corte, Marie Catillon, Erik Bruyneel, Delphine Lentz, Julie Plastino, Jan Gettemans, Evelyne Friederich*

*Corresponding author for this work

    Research output: Contribution to journalArticleResearchpeer-review

    85 Citations (Scopus)

    Abstract

    L-plastin, a malignant transformation-associated protein, is a member of a large family of actin filament cross-linkers. Here, we analysed how phosphorylation of L-plastin on Ser5 of the headpiece domain regulates its intracellular distribution and its interaction with F-actin in transfected cells and in in vitro assays. Phosphorylated wild-type L-plastin localised to the actin cytoskeleton in transfected Vero cells. Ser5Ala substitution reduced the capacity of L-plastin to localise with peripheral actin-rich membrane protrusions. Conversely, a Ser5Glu variant mimicking a constitutively phosphorylated state, accumulated in actin-rich regions and promoted the formation of F-actin microspikes in two cell lines. Similar to phosphorylated wild-type L-plastin, this variant remained associated with cellular F-actin in detergent-treated cells, whereas the Ser5Ala variant was almost completely extracted. When compared with non-phosphorylated protein, phosphorylated L-plastin and the Ser5Glu variant bound F-actin more efficiently in an in vitro assay. Importantly, expression of L-plastin elicited collagen invasion in HEK293T cells, in a manner dependent on Ser5 phosphorylation. Based on our findings, we propose that conversely to other calponin homology (CH)-domain family members, phosphorylation of L-plastin switches the protein from a low-activity to a high-activity state. Phosphorylated L-plastin might act as an integrator of signals controlling the assembly of the actin cytoskeleton and cell motility in a 3D-space.

    Original languageEnglish
    Pages (from-to)1947-1960
    Number of pages14
    JournalJournal of Cell Science
    Volume119
    Issue number9
    DOIs
    Publication statusPublished - 1 May 2006

    Keywords

    • Actin bundling
    • CH-domain
    • Fimbrin
    • Invasion
    • Motility

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