The SH2-containing inositol polyphosphate 5-phosphatase, SHIP-2, binds filamin and regulates submembraneous actin.
SHIP-2 is a phosphoinositidylinositol 3,4,5 trisphosphate (PtdIns[3,4,5]P3) 5-phosphatase that contains an NH2-terminal SH2 domain, a central 5-phosphatase domain, and a COOH-terminal proline-rich domain. SHIP-2 negatively regulates insulin signaling. In unstimulated cells, SHIP-2 localized in a perinuclear cytosolic distribution and at the leading edge of the cell. Endogenous and recombinant SHIP-2 ... localized to membrane ruffles, which were mediated by the COOH-terminal proline-rich domain. To identify proteins that bind to the SHIP-2 proline-rich domain, yeast two-hybrid screening was performed, which isolated actin-binding protein filamin C. In addition, both filamin A and B specifically interacted with SHIP-2 in this assay. SHIP-2 coimmunoprecipitated with filamin from COS-7 cells, and association between these species did not change after epidermal growth factor stimulation. SHIP-2 colocalized with filamin at Z-lines and the sarcolemma in striated muscle sections and at membrane ruffles in COS-7 cells, although the membrane ruffling response was reduced in cells overexpressing SHIP-2. SHIP-2 membrane ruffle localization was dependent on filamin binding, as SHIP-2 was expressed exclusively in the cytosol of filamin-deficient cells. Recombinant SHIP-2 regulated PtdIns(3,4,5)P3 levels and submembraneous actin at membrane ruffles after growth factor stimulation, dependent on SHIP-2 catalytic activity. Collectively these studies demonstrate that filamin-dependent SHIP-2 localization critically regulates phosphatidylinositol 3 kinase signaling to the actin cytoskeleton.
Mesh Terms:
Actins, Amino Acid Sequence, Animals, COS Cells, Cell Membrane, Contractile Proteins, Epidermal Growth Factor, Humans, Melanoma, Mice, Microfilament Proteins, Molecular Sequence Data, Muscle Fibers, Skeletal, Muscle, Skeletal, Myocardium, Oligonucleotide Probes, Phosphatidylinositols, Phosphoric Monoester Hydrolases, Tumor Cells, Cultured, Two-Hybrid System Techniques, Yeasts
Actins, Amino Acid Sequence, Animals, COS Cells, Cell Membrane, Contractile Proteins, Epidermal Growth Factor, Humans, Melanoma, Mice, Microfilament Proteins, Molecular Sequence Data, Muscle Fibers, Skeletal, Muscle, Skeletal, Myocardium, Oligonucleotide Probes, Phosphatidylinositols, Phosphoric Monoester Hydrolases, Tumor Cells, Cultured, Two-Hybrid System Techniques, Yeasts
J. Cell Biol.
Date: Dec. 10, 2001
PubMed ID: 11739414
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