Essential role for the PKC target MARCKS in maintaining dendritic spine morphology.
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.
Calabrese
Barbara
B
Department of Cell Biology, The Scripps Research Institute, La Jolla, California 92037, USA.
Halpain
Shelley
S
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
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