beta 2 integrin phosphorylation on Thr758 acts as a molecular switch to regulate 14-3-3 and filamin binding

Heikki Takala, Elisa Nurminen, Susanna M. Nurmi, Maria Aatonen, Tomas Strandin, Maarit Takatalo, Tiila Kiema, Carl G. Gahmberg, Jari Ylanne (Lead / Corresponding author), Susanna C. Fagerholm (Lead / Corresponding author)

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    109 Citations (Scopus)

    Abstract

    Leukocyte integrins of the O-2 family are essential for immune cell-cell adhesion. In activated cells, O-2 integrins are phosphorylated on the cytoplasmic Thr758, leading to 14-3-3 protein recruitment to the O-2 integrin. The mutation of this phosphorylation site impairs cell adhesion, actin reorganization, and cell spreading. Thr758 is contained in a Thr triplet of O-2 that also mediates binding to filamin. Here, we investigated the binding of filamin, talin, and 14-3-3 proteins to phosphorylated and unphosphorylated beta(2) integrins by biochemical methods and x-ray crystallography. 14-3-3 proteins bound only to the phosphorylated integrin cytoplasmic peptide, with a high affinity (K-d, 261 nM), whereas filamin bound only the unphosphorylated integrin cytoplasmic peptide (K-d, 0.5 mM). Phosphorylation did not regulate talin binding to beta(2) directly, but 14-3-3 was able to outcompete talin for the binding to phosphorylated beta(2) integrin. X-ray crystallographic data clearly explained how phosphorylation eliminated filamin binding and induced 14-3-3 protein binding. Filamin knockdown in T cells led to an increase in stimulated cell adhesion to ICAM-1-coated surfaces. Our results suggest that the phosphorylation of beta(2) integrins on Thr758 acts as a molecular switch to inhibit filamin binding and allow 14-3-3 protein binding to the integrin cytoplasmic domain, thereby modulating T-cell adhesion.

    Original languageEnglish
    Pages (from-to)1853-1862
    Number of pages10
    JournalBlood
    Volume112
    Issue number5
    DOIs
    Publication statusPublished - 1 Sep 2008

    Keywords

    • CD11/CD18 LEUKOCYTE INTEGRINS
    • CYTOPLASMIC DOMAIN
    • THREONINE PHOSPHORYLATION
    • STRUCTURAL DETERMINANTS
    • AMPHIPATHIC GROOVE
    • ACTIVATION
    • PROTEIN
    • CD18
    • TALIN
    • LFA-1

    Cite this

    Takala, H., Nurminen, E., Nurmi, S. M., Aatonen, M., Strandin, T., Takatalo, M., Kiema, T., Gahmberg, C. G., Ylanne, J., & Fagerholm, S. C. (2008). beta 2 integrin phosphorylation on Thr758 acts as a molecular switch to regulate 14-3-3 and filamin binding. Blood, 112(5), 1853-1862. https://doi.org/10.1182/blood-2007-12-127795