Abstract
Spine morphology is regulated by intracellular signals, like PKC, that affect cytoskeletal and membrane dynamics. We investigated the role of MARCKS (myristoylated, alanine-rich C-kinase substrate) in dendrites of 3-week-old hippocampal cultures. MARCKS associates with membranes via the combined action of myristoylation and a polybasic effector domain, which binds phospholipids and/or F-actin, unless phosphorylated by PKC. Knockdown of endogenous MARCKS using RNAi reduced spine density and size. PKC activation induced similar effects, which were prevented by expression of a nonphosphorylatable mutant. Moreover, expression of pseudophosphorylated MARCKS was, by itself, sufficient to induce spine loss and shrinkage, accompanied by reduced F-actin content. Nonphosphorylatable MARCKS caused spine elongation and increased the mobility of spine actin clusters. Surprisingly, it also decreased spine density via a novel mechanism of spine fusion, an effect that required the myristoylation sequence. Thus, MARCKS is a key factor in the maintenance of dendritic spines and contributes to PKC-dependent morphological plasticity.
Publication types
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Comparative Study
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Actins / metabolism
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Analysis of Variance
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Animals
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Cells, Cultured
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Dendritic Spines / drug effects
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Dendritic Spines / physiology*
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Diagnostic Imaging
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Embryo, Mammalian
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Excitatory Postsynaptic Potentials / drug effects
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Excitatory Postsynaptic Potentials / physiology
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Fluoroimmunoassay / methods
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Gene Expression Regulation / drug effects
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Gene Expression Regulation / physiology
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Green Fluorescent Proteins / biosynthesis
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Hippocampus / cytology*
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Immunohistochemistry / methods
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Intracellular Signaling Peptides and Proteins / genetics
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Intracellular Signaling Peptides and Proteins / physiology*
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Membrane Proteins / genetics
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Membrane Proteins / physiology*
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Models, Biological
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Mutagenesis / drug effects
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Mutagenesis / physiology
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Myristoylated Alanine-Rich C Kinase Substrate
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Neuronal Plasticity / drug effects
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Neuronal Plasticity / physiology
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Neurons / cytology*
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Neurons / drug effects
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Patch-Clamp Techniques / methods
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Presynaptic Terminals / metabolism
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Protein Kinase C / metabolism*
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RNA, Small Interfering / pharmacology
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Rats
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Synapses / drug effects
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Synapses / physiology
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Synaptophysin / metabolism
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Tetradecanoylphorbol Acetate / analogs & derivatives
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Tetradecanoylphorbol Acetate / pharmacology
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Time Factors
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Transfection / methods
Substances
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Actins
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Intracellular Signaling Peptides and Proteins
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Marcks protein, rat
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Membrane Proteins
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RNA, Small Interfering
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Synaptophysin
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Myristoylated Alanine-Rich C Kinase Substrate
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Green Fluorescent Proteins
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4-O-methyl-12-O-tetradecanoylphorbol 13-acetate
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Protein Kinase C
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Tetradecanoylphorbol Acetate