Spinophilin is phosphorylated by Ca2+/calmodulin-dependent protein kinase II resulting in regulation of its binding to F-actin

Authors

  • Stacie D. Grossman,

    1. Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, New York, USA
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    • 1

      These authors contributed equally to this article.

  • Marie Futter,

    1. Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, New York, USA
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    • 1

      These authors contributed equally to this article.

  • Gretchen L. Snyder,

    1. Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, New York, USA
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  • Patrick B. Allen,

    1. Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut, USA
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  • Angus C. Nairn,

    1. Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, New York, USA
    2. Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut, USA
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  • Paul Greengard,

    1. Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, New York, USA
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  • Linda C. Hsieh-Wilson

    1. Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, New York, USA
    2. Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, USA
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Address correspondence and reprint requests to Marie Futter, Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA.
E-mail: futterm@rockefeller.edu

Abstract

Spinophilin is a protein phosphatase-1- and actin-binding protein that modulates excitatory synaptic transmission and dendritic spine morphology. We have recently shown that the interaction of spinophilin with the actin cytoskeleton depends upon phosphorylation by protein kinase A. We have now found that spinophilin is phosphorylated by Ca2+/calmodulin-dependent protein kinase II (CaMKII) in neurons. Ca2+/calmodulin-dependent protein kinase II, located within the post-synaptic density of dendritic spines, is known to play a role in synaptic plasticity and is ideally positioned to regulate spinophilin. Using tryptic phosphopeptide mapping, site-directed mutagenesis and microsequencing analysis, we identified two sites of CaMKII phosphorylation (Ser-100 and Ser-116) within the actin-binding domain of spinophilin. Phosphorylation by CaMKII reduced the affinity of spinophilin for F-actin. In neurons, phosphorylation at Ser-100 by CaMKII was Ca2+ dependent and was associated with an enrichment of spinophilin in the synaptic plasma membrane fraction. These results indicate that spinophilin is phosphorylated by multiple kinases in vivo and that differential phosphorylation may target spinophilin to specific locations within dendritic spines.

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