title: Essential role for the PKC target MARCKS in maintaining dendritic spine morphology.
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.
authors.affiliation: Department of Cell Biology, The Scripps Research Institute, La Jolla, California 92037, USA.
authors.forename: Barbara
authors.initials: B
authors.lastname: Calabrese
authors.forename: Shelley
authors.initials: S
authors.lastname: Halpain
mesh_terms: D000199:Actins / Q000378:metabolism; D000704:Analysis of Variance; D000818:Animals; D002478:Cells, Cultured; D049229:Dendritic Spines / Q000187:drug effects / Q000502:physiology*; D003952:Diagnostic Imaging; D004622:Embryo, Mammalian; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D015200:Fluoroimmunoassay / Q000379:methods; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D049452:Green Fluorescent Proteins / Q000096:biosynthesis; D006624:Hippocampus / Q000166:cytology*; D007150:Immunohistochemistry / Q000379:methods; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000502:physiology*; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology*; D008954:Models, Biological; D016296:Mutagenesis / Q000187:drug effects / Q000502:physiology; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D009473:Neuronal Plasticity / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000166:cytology* / Q000187:drug effects; D018408:Patch-Clamp Techniques / Q000379:methods; D017729:Presynaptic Terminals / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000494:pharmacology; D051381:Rats; D013569:Synapses / Q000187:drug effects / Q000502:physiology; D016708:Synaptophysin / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000031:analogs & derivatives / Q000494:pharmacology; D013997:Time Factors; D014162:Transfection / Q000379:methods
chemical_list: D000199:Actins; D047908:Intracellular Signaling Peptides and Proteins; C000619712:Marcks protein, rat; D008565:Membrane Proteins; D034741:RNA, Small Interfering; D016708:Synaptophysin; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D049452:Green Fluorescent Proteins; C020922:4-O-methyl-12-O-tetradecanoylphorbol 13-acetate; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate