Abstract
Dact1 (Dapper/Frodo), an intracellular phosphoprotein that binds Dishevelled, catenins, and other signaling proteins, is expressed in the developing and mature mammalian CNS, but its function there is unknown. Dact1 colocalized with synaptic markers and partitioned to postsynaptic fractions from cultured mouse forebrain neurons. Hippocampal neurons from Dact1 knock-out mice had simpler dendritic arbors and fewer spines than hippocampal neurons from wild-type littermates. This correlated with reductions in excitatory synapses and miniature EPSCs, whereas inhibitory synapses were not affected. Loss of Dact1 resulted in a decrease in activated Rac, and recombinant expression of either Dact1 or constitutively active Rac, but not Rho or Cdc42, rescued dendrite and spine phenotypes in Dact1 mutant neurons. Our findings suggest that, during neuronal differentiation, Dact1 plays a critical role in a molecular pathway promoting Rac activity underlying the elaboration of dendrites and the establishment of spines and excitatory synapses.
Publication types
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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, Non-P.H.S.
MeSH terms
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Age Factors
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Analysis of Variance
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Animals
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Animals, Newborn
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Cells, Cultured
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Dendritic Spines / physiology*
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Dendritic Spines / ultrastructure
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Disks Large Homolog 4 Protein
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Excitatory Postsynaptic Potentials / genetics
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GABA Plasma Membrane Transport Proteins / metabolism
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Green Fluorescent Proteins / genetics
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Guanylate Kinases
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Hippocampus / cytology*
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Hippocampus / growth & development*
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Intracellular Signaling Peptides and Proteins / genetics
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Intracellular Signaling Peptides and Proteins / metabolism
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Intracellular Signaling Peptides and Proteins / physiology*
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Membrane Proteins / metabolism
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Mice
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Mice, Knockout
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Neurons / cytology*
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RNA-Binding Proteins
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Silver Staining / methods
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Subcellular Fractions / metabolism
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Synapses / physiology*
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Vesicular Glutamate Transport Protein 1 / metabolism
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rac GTP-Binding Proteins / metabolism
Substances
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Disks Large Homolog 4 Protein
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Dlg4 protein, mouse
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GABA Plasma Membrane Transport Proteins
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Intracellular Signaling Peptides and Proteins
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Membrane Proteins
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RNA-Binding Proteins
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Slc17a7 protein, mouse
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Vesicular Glutamate Transport Protein 1
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enhanced green fluorescent protein
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frodo protein, mouse
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Green Fluorescent Proteins
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Guanylate Kinases
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rac GTP-Binding Proteins